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DIY Stompboxes => Building your own stompbox => Topic started by: davph30 on September 15, 2006, 03:52:45 PM

Title: Keeley compressor clone
Post by: davph30 on September 15, 2006, 03:52:45 PM
I know that the keeley is based on the ross compressor, does anyone have a keeley schematic with values and semiconductor types ?

what is the differences between the ross and the keeley?

Thanks for reading
Title: Re: Keeley compressor clone
Post by: markm on September 15, 2006, 07:03:29 PM
All ya gotta do is build a stock DIY Ross comp build and you pretty much will have a Keeley.
I can't say the exact differences but, I think he uses different pot values/tapers and 1% metal film resistors,
"hi-fi" caps and supposedly OEM trannies.
I built the tonepad Ross clone and about a week after doing so I happily e-bayed my Keeley to buy more parts!
I haven't missed it one bit  ;D
Title: Re: Keeley compressor clone
Post by: Gus on September 16, 2006, 11:09:00 AM
I find this question kind of funny.
Title: Re: Keeley compressor clone
Post by: davph30 on September 16, 2006, 11:30:05 AM
why is it funny Gus? I'd just like to know the exact differences in values ect
Title: Re: Keeley compressor clone
Post by: Ed G. on September 16, 2006, 10:16:54 PM
Kind of an inside joke here.
Lots of people here figure Keeley got at least some of his ideas from this forum.
There are lots of mods for the Ross compressor here. Do a search.
Title: Re: Keeley compressor clone
Post by: markm on September 16, 2006, 10:25:52 PM
Kind of an inside joke here.
Lots of people here figure Keeley got at least some of his ideas from this forum.

That would not surprise me at all.
Title: Re: Keeley compressor clone
Post by: Dragonfly on September 17, 2006, 12:00:20 PM
Lots of people here figure Keeley got at least some of his ideas from this forum.

...kind of an understatement, don't you think ?  :D

seriously...to the original poster....build a ross, use MF resistors and either MF or PF caps, and you'll be 99% there...

AC
Title: Re: Keeley compressor clone
Post by: Ed G. on September 17, 2006, 01:49:30 PM
Just going from memory, Jay Doyle and Mark Hammer have some really good posts on the Ross chorus. With some of their suggested tweaks you can put together a comp that should surpass Keeley's.
Title: Re: Keeley compressor clone
Post by: bancika on September 17, 2006, 05:04:36 PM
yeah, there's vero layout aroun here with both RG's and Hammers mods included. I finshed one comp done according to it, so it's verified :)
Title: Re: Keeley compressor clone
Post by: Ed G. on September 17, 2006, 06:22:52 PM

...kind of an understatement, don't you think ?  :D


Yeah, I was just trying to be nice  ;)
Title: Re: Keeley compressor clone
Post by: markm on September 17, 2006, 09:33:19 PM
Just going from memory, Jay Doyle and Mark Hammer have some really good posts on the Ross chorus. With some of their suggested tweaks you can put together a comp that should surpass Keeley's.

Absolutely.
It's not really all that difficult to surpass Keeley's Comp.
Matter of fact, from what I have seen of the PCB, it is quite comparable ( :icon_biggrin:) to the TP layout.
Title: Re: Keeley compressor clone
Post by: analogmike on September 18, 2006, 10:28:02 AM

I can't say the exact differences but, I think he uses ... supposedly OEM trannies.

nope, he ran out of the 2SC1849R a year or more ago, he sells a lot more compressor pedals than we do (good marketing and builds them a lot faster) . We have some NOS trannies left but getting low....
Title: Re: Keeley compressor clone
Post by: davph30 on September 18, 2006, 06:45:51 PM
thanks for your help guys, i've ordered the parts and going to give it a try, will try it with 2n5088's first. If i get a pile how do i best match them?
Title: Re: Keeley compressor clone
Post by: markm on September 18, 2006, 07:17:25 PM

I can't say the exact differences but, I think he uses ... supposedly OEM trannies.

nope, he ran out of the 2SC1849R a year or more ago, he sells a lot more compressor pedals than we do (good marketing and builds them a lot faster) . We have some NOS trannies left but getting low....

Interesting.
I think his website still promotes this but, I could be wrong and really have no desire to look either!  :icon_lol:
Title: Re: Keeley compressor clone
Post by: Gilles C on September 18, 2006, 07:32:58 PM
Just in case you need more info, if you don't already have it.

http://fuzzcentral.tripod.com/compressor.html

Gilles
Title: Re: Keeley compressor clone
Post by: Fp-www.Tonepad.com on September 18, 2006, 09:40:10 PM
a clone of a clone can be the clone of the original  ::)

Seriously, if one wanted to clone a pedal that is itself a clone, a requirement would be to replicate the dedication in construction and part selection, since the circuit itself is not what's 'special' about a boutique pedal. There is a certain skill there, which makes the difference, IMO, not a small difference.

Fp
Title: Re: Keeley compressor clone
Post by: RobertKeeley on September 19, 2006, 05:26:04 AM
Howdy folks, or maybe Bullocks to some....
Anyway, listen all of you that continue to guess, surmise, accuse, etc....
I copied the a Ross schematic by RGKEEN in April or so of 2001.
Since then, at least a 100 design changes have been made....to say that is probably a huge understatement, things get improved here all of the time.
I have not changed my design by looking at or learing about TP, M. Hammer's, Analogman's, or ANYONE'S ideas except for four cases.
I've talked with Jack Orman about some mods and made changes, I pay him from time to time for the help.
I've changed things based on the techs opinions here at the shop.
I've talked with my dad (also an EE) about the pedal.
Things I do on my own.
I've gotten mods from Jeorge Tripps and his ideas on the pedal and a whole slew of stuff thrown at me over time...but have used NONE of it.
Nothing, ABSOLUTELY NOTHING I've seen on this forum has EVER been used.  I'll let you know when I do learn from this place and decide to utilize the information.

Analogman.  Dude, you need to stop your guessing and crying about everything related to my business.  Grow up man.
You have some silly comment if I run a full page ad, sell on ebay, if I talk about things that matter like customer service, you think you know when I run out of a part, etc, etc, etc...
Since I blew past you years ago, I've forgotten about you.  Forget about me!  THANKS!  ;D
hmmm...the last time I REALLY thought about you was when I paid well over $60,000 in federal income taxes a couple years ago.  The roads and schools and police needed the help, I was glad to give.   ;)


Just about anyone can build a compressor.  Millions can build a compressor better than the product we offer.  That is not the point.  We make something that sounds good and we support it in terms of sales, service, and supply.

You know what I do?!?!?!?  I laugh at you guys that think you know how and what and why I do things!!!  ;D
What I DO is try to grow a business and a family.  For the 27 or so people I employ, we give full medical and dental insurance coverage for a tiny cost, large vacation times, paid education Regardless of Degree Type, IRA Investing with matching, schedules to fit families and education, birthday parties, company events, a chance for people to grow and create their own future here and outside the company.

WHAT DOES THAT MEAN?  That means that I'm not going to let my customers down.  I've got things under control enough to offer that by making people happy and helping them with their tone (even if it's not our mods, or even our pedals, etc...).  I don't have to worry about looking around this place but once every couple years and wonder how over 1/2 of you are so negative and wrong about what you surmise as my history and business.

SO think what you want about something that started in early 2001 and you guys can still be jealous and pontificate about it all you want.  I do need to get back to family, friends and our killer customers!!!

Robert
Title: Re: Keeley compressor clone
Post by: Ken on September 19, 2006, 07:20:11 AM
Robert,

Mate have a stiff drink.....................

I really don't think anyone here has problems with you.

I think it's great that you can make a living for yourself and others out

of something most of us treat as a hobby...well maybe more than a hobby.

I don't see how you feel threatened ?

If I'm missing something please say so .

Cheers Ken.  :icon_biggrin:
Title: Re: Keeley compressor clone
Post by: amz-fx on September 19, 2006, 07:51:18 AM
I'll confirm much of what Robert says...   I talk with him every month on the phone and we discuss many ideas about circuit design, the NAMM show, how to run a business, the weather, or why our wives are on our butts :icon_mrgreen:

Robert has a business to run and it takes much more time to manage employees and products than some people understand, which leaves little time for visiting forums. Also, I know he intentionally does not read this forum because he does not want to be suspected of borrowing ideas...  that might be a bad idea because I've found that if you are present on a forum then the people tend to be more considerate. If you are absent, then you lose that personal touch, and some folks start to become loose with their consideration/respect for you, or your business. 

re: the Attack mod.  It wasn't invented on this forum....  maybe it was independently derived by someone here, which is certainly possible, but I have seen the exact same type of design on a commercial pedal that long predates any discussion here.  It's just a logical mod that a competent designer can arrive at by looking at the circuit.  It is easy for it to have been developed independently by Keeley, AnalogMike or this forum without input from each other.

re: the Keeley compressor. It started life as a Ross/MXR clone, and he has always been upfront about acknowledging that. There are lots of mods to the circuit that improve upon the basic design and as Robert stated, I contributed some of them. We talked about a new mod to it just recently, which I don't know if he has implemented yet, but that particular mod hasn't been seen on any forum... however, it is logical and it would not surprise me if it did appear one day.

Quote
What I DO is try to grow a business and a family.  For the 27 or so people I employ, we give full medical and dental insurance coverage for a tiny cost, large vacation times, paid education Regardless of Degree Type, IRA Investing with matching, schedules to fit families and education, birthday parties, company events, a chance for people to grow and create their own future here and outside the company.

This speaks for itself.    I'll only confirm that we discuss some of these items on the phone from time to time.

I know Robert has a good feeling about DiY hobbyists - he started as one - and believes as I do that 99.5% of them are great people who are considerate and honest.  Please return the sentiment.   :icon_cool:

Best regards, Jack
Title: Re: Keeley compressor clone
Post by: StephenGiles on September 19, 2006, 08:05:14 AM
I for one have no reason to think other than Robert is a good egg. (quaint English expression). He obviously looks after his staff.
Title: Re: Keeley compressor clone
Post by: Ken on September 19, 2006, 08:07:22 AM
Jack,

I have alot of time for people like Robert who post some of their mods on his own WWW.

and obviously looks after his staff.

I just think he needs to be careful not to alienate himself from the DIY community.

Cheers Ken.
Title: Re: Keeley compressor clone
Post by: RobertKeeley on September 19, 2006, 09:55:18 AM
Thanks for the kind words fellas...
It's just that every once in a while the Vultures get to me.  Heck, the whole point of this place is to help people, to share schematics and ideas, and to build pedals.  It's not DIYANDDON'TSELL.  There has been a lot of things stated in the past about how I started that are so wrong and I wish people would get it clear and straight.  I see the same hate thread from 5 years ago pop up everytime someone talks about a TS9 mod of mine on this place. Or, three page posts on how a certain pedal or mod to a design of mine should work, can't work and is wrong, etc...
I did give out mods and will continue to over time.  The only problem with giving out mods now is that I can't support all the questions about DIY so it becomes something that subtracts from my service to others.
My original post stands as stated, some folks just need to find some one else to complain about.  I know where I got the source and insipration for this business (not my first choice by the way, my wife talked me into it, amplifiers were the object of desire then!) and it's not from the sources or methods some folks always spout.

Thanks for listening and keep on strummin'!!!
RK

Title: Re: Keeley compressor clone
Post by: Ken on September 19, 2006, 10:01:40 AM
Robert,

It pays to vent occasionally...

keep up the good work......don't forget us little builders.

Cheers Ken.   ;)
Title: Re: Keeley compressor clone
Post by: analogmike on September 19, 2006, 12:47:14 PM

I just think he needs to be careful not to alienate himself from the DIY community.


I think some people should switch to decaf!  ;D

Alienation appears too late. Scolding people, bragging to everyone how rich he is, how jealous everyone else is, how he blew by competitors, and how he came up with everything himself does not seem to be very endearing to me.

He needs to chill out instead of getting all defensive.  And needs to check his dealers' websites which list the 2SC1849R transistors, he is an honest man and must have forgotten to inform them.

Have fun!
Title: Re: Keeley compressor clone
Post by: Jay Doyle on September 19, 2006, 01:38:47 PM
I copied the a Ross schematic by RGKEEN in April or so of 2001...
...
Since then, at least a 100 design changes have been made....to say that is probably a huge understatement, things get improved here all of the time.
...
SO think what you want about something that started in early 2001 and you guys can still be jealous and pontificate about it all you want. 

I think that the rub comes when one hears that you got the schematic from R.G. in 2001 but mean to have us believe that the schematic was ALL that you got in 2001 or before. Like 'geofex.com' was a typo and you ended up there only to find to your delight: Look! The Ross compressor schematic! AND, 2001 may sound like a long time ago, but it certainly wasn't before this forum.

I know that I was tracing mine in 1999, that I received a factory schematic from a wonderfully generous member here shortly after to confirm, that I had built my own and was touring with it by mid-2000, and that I in no way had the skill or ability back then to figure out the circuit and the tweaks I did all on my own. I had learned them here and through a lot of my own research, but mostly here. Point being, not only was the schematic up in 2001, but by then so was a lot of good info on the Ross/DynaComp circuit. To think that you just found the schematic and then shut the door behind you to figure the rest out on your own is a bit hard to fathom. All we have is your word that you didn't. Plus, your peers haven't left us with the sweetest taste in our mouth around here when it comes to lifting their R&D from the info freely presented. And because of that, it has soured a lot of folks on posting new ideas, which has been a severe detriment to this community. So if there is hostility toward you, you should understand where it originates as well as how you may have contributed to it.

Also, showing up to take a swipe at another builder and a lot of us around here, bloviating about your worth, while also talking about all of these great things you have done to the circuit, without mentioning or explaining a single one of them in the process, is bad form. If you want to get into a pissing match with another builder, fine, but if you are going to do it here, please ADD something to our knowledge base, otherwise, please do it on HC or one of the other forums that type of discussion is made for and you are also a member of.

And to me personally, as I was very interested in the Ross, was a Phish fan, and followed your pedal quite closely, a lot of the 'improvements' that made it into the marketing copy on your site seemed coincidentally to be along the lines of stuff talked about here. But in the end, only you know where they came from, and how/when/if you attribute anything is up to you.

Thing is, you run a great business, some of us here may feel that the mods you sell are a waste of money, or your pedals may be overhyped clones, but they aren't for the guy who doesn't want to bother with picking up a soldering iron. You fill a need. 

Plus, you employ 27 people in what sounds like a very open, rewarding and warm working environment. And that, in the end, is far more important than the circuits you sell, no matter where they come from.

But it wouldn't have taken much to be well thought of around here, most of us know the work of a boutique builder is in the business not the circuits. Most likely, all it would have taken would have been a link on your page saying "I would like to thank all of the folks at diystompboxes.com and the DIYFX community as a whole for their insight, inspiration and understanding." with possibly a link or two to some of the more prominent DIY sites.

And while I'm sure you did come up with a lot of the stuff you do on your own, you DID NOT get it all by yourself: at the very least you got a Ross Compressor schematic.

Regards,

Jay Doyle
Title: Re: Keeley compressor clone
Post by: davph30 on September 19, 2006, 01:56:51 PM
Thanks for your replies, I dont want to start any arguements between anyone I'm only a DIY builder who wants to have the best tone from the designs of the best pedels from the last 50 years and have the satisfaction of building them myself. Which im sure all of u understand. If any of u would like to help that would be great and apreciated. Any mod and build tips will only help me. Its hard enough getting all the parts here in scotland.
I dont own a business and dont intend to, its all for fun and the pleasure.

Thank you all again

Dave Phillips
Title: Re: Keeley compressor clone
Post by: modsquad on September 19, 2006, 02:09:25 PM
Just an outside observation from someone who has been on this forum a short time.   Anyone with with EE knowledge could build or mod anything found on this forum.  I have learned that most effects circuits have basic audio and EE engineering principles built in.   It just takes someone with an idea to tweek it or put the pieces together.   It seems that with an original schematic even I could plug and play some of the sections, tweek it etc. and come up with something that someone else is capable of.

I have made some of Keely's mods to my commercial pedals and gone..."Is that all there is to it?".    So I realize this stuff isn't rocket science, its more about understanding the science and being able to solder.  I am not defending Keely, only that there appears to be an attitude of "Hey I thought of that first" mentality.   I don't care either way I have learned to read schems, burn my fingers, and EE principles of opamps, etc. on hear.   

I would love to be in the position that RK is in.   I love building these things and watching people play them and go "WoW, thats awesome".   But it takes a tremendous amount of investment, manpower, and MARKETING.  What RK has done is a good job of marketing his stuff.  Yes most of us could do the mods for pennies on the dollar, but guess what capitalism is alive and well.

And no I am not endorsing Keely, or defending his post.  This was just my two cents worth.   Now back to learning how to use this damn breadboard.

Stan

 
Title: Re: Keeley compressor clone
Post by: Mark Hammer on September 19, 2006, 02:52:53 PM
I guess I have to chime in here, don't I?

The after-market mods game is a funny one.  On the one hand, you're taking a product that is presumably good enough that a lot of people felt justified in buying it in the first place.  So, not your own IP, and it's not exactly as if you're recycling phone books or plastic milk jugs that people have tossed away to make completely different things.  At the same time, you couldn't stay in business if you couldn't persuade people that paying almost as much as the original product cost for a few small improvements to the product was a good thing.  I'm not accusing anyone of hucksterism.  Rather, if very few people believed that it was worth spending money for a few changes to an existing decent commercial product....well, you'd have an interesting hobby but you'd be in another line of work as far as paying the mortgage and health insurance went.

Now, how do you go about persuading them?  Well, snake oil claims will take you a little ways, but to deliver enough business that you can pay salaries and generous benefits for 27 people, and do so for 5 years, it takes something a little more substantive than mere snake oil claims.  You have to, have to, um, how you say?....deliver the goods.  Now, it's not as if Boss develops pedals that are half-assed.  They certainly don't work on them for a couple of months and go "I'm bored.  Let's just wrap this up and work on something different."  They make a point of trying to produce pedals that will have the greatest possible broad appeal.  They have to sell millions of 'em because that's what pays for the glossy catalogs you get for free from the store and trade shows.  That,s what pays for web-site development.  That's what pays for the big booths at trade shows.  That's what pays for the custom chassis and custom components.  That's what pays for the R & D.  So Bob and his staff are not busy modding sheer crap, and they're not hoodwinking people into thinking that it's crap because those people have already bought something they thought was good and are hoping it will be just a bit better because they are planning on depending on it.

That's why the after-market mod biz is so weird.  You're depending on clients who think something is good enough...just not quite good enough.  Fortunately, spending $50 or whatever more on your $40 DS-1 is far more affordable than spending $25k on "ricing up" your Honda Civic or Toyota Echo, so it is a whole lot easier to get customers under those circumstances.

Can you sustain that sort of business by being innovative in the traditional sense of offering wholly new ideas?  Not really, because you're confined to what is possible within the limits set by the very commercial products you mod.  So the mods will almost, of necessity, be modest.  That doesn't mean moot, just modest in the sense that they can't stray too far from the original intent and design of the product.  People will buy mods for their compressor to make it a better compressor, but not likely to turn it into a fuzz.  If they wanted a fuzz they would have bought one.

These days, after-market mods is only a portion of what Bob Keeley does.  And wisely so.  There is ony so far you can take that, particularly if you are willing to share the knowledge with others.  Hell, even if you aren't willing to share knowledge, how long would it take to comprehend that silicon diodes had been changed for LEDs?  We are constantly swamped by postings here about this Keeley mod and that one.  Bob gets revenue from doing them, but he certainly doesn't collect magic money each time he is mentioned here.  So there are limits to how much business you can do in the after-market mod business.

About the compressor mods....

There are some mods that get attributed to me.  I might be the guy who ends up explaining them to others more often than anyone, but *I* got them after looking at the schematics for a bunch of other compressors that existed long before I understood them.  The variable recovery mod goes backto the good folks at Boss and probably several other companies who were using the identical full-wave rectifier circuit as found in the Dynacomp.  It wasn't until I understood enough to see the circuit fragments in the schematics for what they were that I realized how much commonality there was between them, and that what I saw in the Boss schematic could easily be imported into the Dynacomp and any other 2-knob OTA-based compressor.  If you know how old the CS-2 is, then add a few years and that is at least how old the variable recovery thing is.

Of course, it is one thing to know that recovery CAN be made variable, and another to do the trial and error work to identify what sorts of recovery-time differences are meaningful to the human ear and musician's ear.  I'm assuming Bob has done that work and for that he deserves credit even if the variable recovery idea was not his or mine or Jack's in the first place.

Actually, what I find funny in all this who-got-what-from-who discourse is that Ross stuff was largely an almost exact copy of MXR stuff (with a mod here and there) yet was marketed as if it were a wholly different product.  At no time was it ever presented as being just MXR stuff with some mods.  In that respect, what folks like Bob do is far more intellectually honest than the very products they mod!  :icon_rolleyes:
Title: Re: Keeley compressor clone
Post by: modsquad on September 19, 2006, 03:05:40 PM
Well said.  I think we're just jealous that Bob makes a good living at it.  :icon_mrgreen:
Title: Re: Keeley compressor clone
Post by: Jay Doyle on September 19, 2006, 03:39:27 PM
Thanks for your replies, I dont want to start any arguements between anyone I'm only a DIY builder who wants to have the best tone from the designs of the best pedels from the last 50 years and have the satisfaction of building them myself. Which im sure all of u understand. If any of u would like to help that would be great and apreciated. Any mod and build tips will only help me. Its hard enough getting all the parts here in scotland.
I dont own a business and dont intend to, its all for fun and the pleasure.

Thank you all again

Dave Phillips

Dave,

Sorry for posting without answering the original question, but a search for 'Ross Compressor' should yield a lot of information for you. Sometimes posts unknowingly open cans of worms and you don't get your answer.

But in brief, here is what I have found:

- The first cap to ground the signal sees is NOT .0022uF as on R.G.'s schem http://www.geofex.com/FX_images/rosscomp.gif (http://www.geofex.com/FX_images/rosscomp.gif), but 220pf. It makes a big difference.

- Metal film resistors don't need to be everywhere, but sometimes when ordering parts it is easier to just get them all metal films. The most important ones, in order, are: the 150k directly after the CA3080 (the 3080 outputs a current so the noise dropped across the resistor here is significant), the 10k in series with Q1's base, the 10ks on the emitters and collectors of Q1 and Q2, the two 1Ms and the 15k on the inputs of the 3080, the 470k/470k and 220k/220k bias strings feeding the base of Q1 and the 2k trim respectively (with the resistor AFTER the cap being more important in the pair) and the 10k in series with the Output pot (which I normally just leave out as it only serves to limit the output available.)

- I've always used 1uF tantalum caps because the tone difference was not so sufficient (and except for the 1uF after Q1, hardly/not at all) as to cough up the extra dough and board space for 1 uf films.

- The two most important caps in the board IMO are the 220pF cap on the input and the .001uF on the output of the 3080. The .001uF cap serves to keep the 3080 from oscillating in the MHz, frequencies which the 3080 can hit with ease. Make sure this is a high quality film cap with low leakage and ESR. There are only three other caps in the signal path, the .01uF on the input, the 1uF after Q1 and the .05uF preceding the Output pot. These, along with the .01uF/15k/1uF and the 220pF input cap are the best place to try out different types of caps and values for tonal changes.

- You will most definitely want to audition different 3080 chips, the noise level does vary between them.

- The transistors. This is most often the source of the 'mojo' claims and, as with most mojo, isn't really that big of a deal. Only Q1 and Q2 are in the signal path, and even then only as followers, so they would be the best ones to select for noise/tone. Q3 and Q4 are set up in a way that it would seem to make sense to match them. BUT, their gain is kicked up so high, without an emitter resistor and so any signal over .6V will turn them on and HARD, that small differences in Qs will not matter here. Sure, you would like both halves of the signal to be rectified the same, but the FWR signal is integrated in the 10uF cap and that evens out a lot of the difference between the two. Also, this isn't a studio quality compressor, this is a nuts and bolts guitar comp that pretty much just sustains the signal. Normally, I just use high gain/low noise transistors and audition a couple for Q1 and Q1. Q5 is used to drive the Iabc port on the 3080 and completely out of the signal path so another low noise/high gain, is fine here as well.

- The base of Q5 is the point for insertion for any attack and decay network you want to use.

- There is one last thing that makes a difference and was on the original factory schematic that I haven't seen posted anywhere else. PM me.

Not so short, but I hope that this helps.

Regards,

Jay Doyle
Title: Re: Keeley compressor clone
Post by: davph30 on September 19, 2006, 03:56:01 PM
Thanks for the reply Jay i'm sure it will help


Dave
Title: Re: Keeley compressor clone
Post by: Gilles C on September 19, 2006, 04:04:28 PM
Thanks for the info Jay. I have the Ross Compressor in mind for later, and I would like to make sure I use the correct parts.

I began collecting infos, but as you said, things are not always what we are looking for.

Gilles
Title: Re: Keeley compressor clone
Post by: Mark Hammer on September 19, 2006, 04:21:43 PM
Thanks Jay.  I owe you one.
Title: Re: Keeley compressor clone
Post by: puretube on September 19, 2006, 04:51:19 PM
Quote
Have fun!

I do!!
 :icon_biggrin:
Title: Re: Keeley compressor clone
Post by: RobertKeeley on September 19, 2006, 05:27:30 PM
Thanks and sorry at the same time for letting me vent a bit, since it was a rude morning thing to wake to.  Still mean things I said.
Okay, mistake on my part.  over 100 design changes....over 100 PRODUCTION CHANGES...I mean by that, I ain't the best EE in the world, nor builder, nor anything else.  I had the second part of the statement more correct, we are always making improvements.
To those that wonder what we change.... Things so small as to not even be worth counting.  In effect, I've made may half a dozen or dozen electrical changes of an significance...more of very, very small detail like part quality.

THANKS SO MUCH MARK HAMMER....I wondered for years why no one cussed the ROSS DUDES?!?!??!?!  What did DIY people wright letters back and forth back then and slam that poor guy all the time!?!?!?!

Yeah, it doesn't take much to look at several 2 knob comps and find out there are a bunch of things you can borrow from and make 'yours' better.

Why do I talk about money...well...I hope some of you DIY guys go out and become builders and business owners.  Growing a family like this is so rewarding, so difficult, so painful...I wish it on all of you!   ;D

Robert

Title: Re: Keeley compressor clone
Post by: davph30 on September 19, 2006, 06:01:56 PM
Robert thank you very much for your PM and help.

 I'm glad I have the best person to anwer my questions

I'm glad I started this post now, u should see the smile on my face!!

Dave
Title: Re: Keeley compressor clone
Post by: markm on September 19, 2006, 06:05:12 PM
Ya know,
Today's DIY guy is tomorrow's Boutique builder!
That's my bit of philosophy for today   :icon_razz:
Anyway, I suppose I myself owe much to Robert Keeley (even though he didn't return my e-mails and phone calls  :icon_confused:)
It's because of him that I got into DIY. I was an owner of a Keeley Comp and after looking at it inside and out I couldn't see any reason what-so-ever why I couldn't build one just like it......so, I did!
And that was my introduction to doing DIY and I have been rolling with it ever since.
So guys, RK is the reason y'all are stuck with ME!  :icon_lol:
Of course, RK could always PM me if he wanted to....... ;D
Title: Re: Keeley compressor clone
Post by: RobertKeeley on September 20, 2006, 05:56:10 AM
Howdy!
Sent you a PM (after I figured out how to do one  ???  ;D  )
The variable recovery or attack control, etc.  Those are things I got from the CP9 by Ibanez I had from living in West Germany, along with my Aria Pro ;-) .  Slightly interesting story, several years ago, really wish I knew when, I started doing them when a humbucker customer was going to return a pedal.  I wanted to figure out why they were having poor tone/performance, distortions, etc.  So I would do some 'back them',  again don't remember how many years ago.  I did experiment with different versions and found out that I didn't like the exact copy of the Ibanez one and that on some of the keeley comps it just plain didn't work because of significant distortion. So, I ended up finding out that the transistors I was using were different (duh!) and that I had to simply crack out the books and find out 'where they wanted to be' without distortion.
Sure, there was that cap mistake on the schematic and things to make sure were matched, that was the best part of the beginning of the ROSS CLONE ERA, people would send me their compressors that they bought from somebody and I would find just a simple copy of the schematic built, easy fix.
I also did tweak/diddle-stick/calculate/alter just about every part in the unit....just so that I had a decent understanding of it.
I have built them with different IC's, different rectifier circuits, build different input and output buffers for a variety of uses and to match other signals equipment (including one for a TV audio circuit/speaker....don't you just hate LOUD commercials, etc...
In this Late 2006 time frame, RoHS compliant matters force a change.  We are nearly complaint to the letter of the law on about 85% of our product line, so to be analyzed more strictly and technically.  So a true clone to Europe is not legal at all anymore.  At least that is my best understanding.
Take care folks,
Yes, decaf ain't to bad an idea....  :-[

Robert
Title: Re: Keeley compressor clone
Post by: BD13UK on September 20, 2006, 11:42:53 AM
For the most part a person who gains info and ain't too wise re; pedal building it was nice to see someone like Robert Keeley come on the forum. I've built a few pedals mostly Fuzz and overdrive stuff thanks to people like RG Aron Torchy Mark Hammer Dragonfly Jack Orman etc etc. These aforementioned contributers are worth their weight in gold when it comes to this stuff, so I for one am most grateful. I appreciate that Robert Keeley like Mike Fuller etc etc are running a business and can understand that they have their own ways/methods of dealing with things and can therefore appreciate their situation with regard to their own circumstances. It would be so nice if people and for the most part on this forum this is the case, We could all get on well and usually that is the situation except for the odd occassion  when there's a kick off over very litte usually. I wish Robert Keeley good luck in His endeavours to make and sell gear exactly the same as Ibanez Boss and many other companies do so lets all just be grateful for the info that We have via this wonderful site and it's contributers
Title: Re: Keeley compressor clone
Post by: davph30 on September 20, 2006, 01:46:34 PM
Hi guys, how r u all today?

Thanks for all the pm's asking me what Mr Keeley said to me, I would gladly share any info I have but as he Pm'd me I feel I shouldt give out any private info given by him unless he agrees. I am honoured he even spent the time to reply to the post.

sorry again I dont want to offend anyone and am very greatfull for any help, hope u all understand my position

thanks

Dave
Title: Re: Keeley compressor clone
Post by: Jay Doyle on September 20, 2006, 03:13:42 PM
Thanks Jay.  I owe you one.

Mark,

Not a problem, glad to get it in the 'Search' function, at least the stuff I know. But after all the times you've posted the same stuff, I think I'm still well in your debt.

Jay
Title: Re: Keeley compressor clone
Post by: davph30 on September 21, 2006, 10:53:43 AM
I've still not decided on any mods or changes yet, any more suggestions would be great

thanks

Dave
Title: Re: Keeley compressor clone
Post by: RobertKeeley on September 23, 2006, 08:19:09 AM
You can post any of my PM's about this subject.
No problem.
Robert
Title: Re: Keeley compressor clone
Post by: davph30 on September 24, 2006, 10:18:03 AM
Hi Guys, just to let u know Robert told me he now uses MPSA18 transistors in his compressor.

Anyone got any other usable mods or ideas?

Cheers

Dave
Title: Re: Keeley compressor clone
Post by: markm on September 24, 2006, 10:53:34 AM
Hi Guys, just to let u know Robert told me he now uses MPSA18 transistors in his compressor.


 ???
Interesting........
Title: Re: Keeley compressor clone
Post by: davph30 on September 24, 2006, 11:20:10 AM
I really don't have any magic or other things I think make the compressor sound good or otherwise.  I can tell you that tonepad (think that is it?) has boards for the pedal.
I use MPSA18s for the transistors now.  I used to do half and half for about the last year or so...using the 2sc1849 units in two positions.  I've had people that have owned different compressors over the years say this latest version is the best.  SO the 2sc trannies might be vintage correct, the mpsa seems to make people happy.
The rest of the parts are metal film resistor, metal film caps by panasonic.

As said by Mr Keeley

Dave
Title: Re: Keeley compressor clone
Post by: Gilles C on September 24, 2006, 01:02:16 PM
THey say about the MPSA18 in the Fairchild specs... (The Motorola is the original).

NPN General Purpose Amplifier

This device is designed for low noise, high gain, applications at collector currents from 1m A to 50 mA. Sourced from Process 07. See 2N5088 for characteristics.
 ???

Is there a difference in sound when a 2N5088 is used? If so, maybe I would use a Motorola MPSA18 to make sure it is not a 2N5088 labeled MPSA18 by Fairchild or another company...

Gilles
Title: Re: Keeley compressor clone
Post by: markm on September 24, 2006, 01:26:54 PM
hmmm...Even more interesting.....
I used 2N3904 for my Dynacomp build from the USTOMP layout, (very nice layout BTW!) and I used 2N5088 for my
RossClone built using the TP layout (which is also a very nice layout!).
Check out FuzzCentral as Phillip used 5088's for his build of the Ross too.
He states in his notes that the 5088's are higher gain (we do know that) but that they would sound "cleaner" in that circuit.
Aren't the MPSA18 usually used in Hi-Gain overdrive/distortion circuits?
Title: Re: Keeley compressor clone
Post by: Mark Hammer on September 25, 2006, 10:43:39 AM
hmmm...Even more interesting.....
I used 2N3904 for my Dynacomp build from the USTOMP layout, (very nice layout BTW!) and I used 2N5088 for my
RossClone built using the TP layout (which is also a very nice layout!).
Check out FuzzCentral as Phillip used 5088's for his build of the Ross too.
He states in his notes that the 5088's are higher gain (we do know that) but that they would sound "cleaner" in that circuit.
Aren't the MPSA18 usually used in Hi-Gain overdrive/distortion circuits?
See my earlier posting. I used MPSA18 for the input and phase-splitter/driver transistors (before and just after 3080), 2N3904 for rectifier, and 2N5089 for output transistor.  Sounds nice and is pleasingly quiet.  I did this just based on the naive assumption that the input and output stages ought to be higher-gain low-noise devices, and happily this hunch was right.  Not sure if RK's decision to use the same device was an instance of great minds thinking alike or fools seldom differing! :icon_lol:

(The switch to 2N5089 for output was because I ran out of MPSA18's)
Title: Re: Keeley compressor clone
Post by: markm on September 25, 2006, 12:05:44 PM
Mark,
an chance that you could label which tranny does what on the tonepad layout?
For educational purposes   :icon_wink:
Title: Re: Keeley compressor clone
Post by: Mark Hammer on September 25, 2006, 12:14:21 PM
Q1 is the input transistor.  Q2 is the phase-splitter/output transistor.  Using a high-gain/low-noise for these two devices is helpful.

Q3 and Q4 can be cheap "garden variety" 2N3904 types that don't have to be anything other than within spitting distance of each other since they only carry control signal, not audio signal.  Matching them is not counterproductive, per se, but as some have wisely pointed out potentially a waste of effort given tolerances in other components.  So at least make sure you don't have one with hfe=124 and the other with hfe=840.  Q5 sums them and feeds the current-control line on the 3080.  Again, not an audio signal carrier, so hiss potential not that big an issue as near as I can tell.  However, it does supply the current that controls the gain of the 3080, so I gather higher-gain units are preferable here.

I will happily defer to others with more knowledge of transistors (which is a VERY large group of people).  I'm just telling yu what I used and what the different devices do.
Title: Re: Keeley compressor clone
Post by: beatstrat on September 25, 2006, 12:30:01 PM
Good thread for me.

I used 5088s for all 5 positions (out of ignorance, I guess).  I used metal film caps for all values 1 uf and smaller and tantalum caps for the 10 ufs.  (I would like for someone to point me to a source for high qual/low noise electrolytic caps).  I don't seem to have a noise issue - using this pedal with my live rig, it works fine and doesn't (seem to) accentuate/exacerbate any noise issues already present (Stratocaster!).

I would like for someone to comment on the overall intrinsic tone of this comp.  I've used a Boss CS-3 (tweaked) for many yrs and just recently built the Ross clone mostly to see if I could not hate it as much as I've disliked various Dyna Squash comps that I've played thru (incidentally) over the yrs.  With the various Attack/Release tweaks, I've not got a squash circuit, but it seems to impart a plastic quality to the gtr tone.  I suppose it's the nature of the beast (3080E?), but if there's one thing I'd really like to tweak/change about this circuit, it's this 'plastic'/whatever tone.  In thinking about it, it seems that this coloration is mainly present (audible, noticable?) in the upper mid and high frequencies.  Part of it is the squashing nature, I'd guess.  Is there anything that you collectively know to be able to change this?  The CS-3 doesn't give me this same type of tone issue.  (Obviously, I'm aware that if I don't dig the tone of the Ross, just use the one that I like - that's not really what I'm after here).

Any help/ideas/thoughts would be greatly appreciated.  Thanks.


Edit - I couldn't get rid of the itallics.. ?
Title: Re: Keeley compressor clone
Post by: Mark Hammer on September 25, 2006, 01:06:38 PM
Unless they deliberately include some circuit changes to compensate for it, just about EVERY compressor I've ever tried introduces some illusion of high-end loss as a result of the compression process.  I've never really understood it before, although now that I think about it, perhaps that's because the most treble occurs at the onset of the note, which is coincidentally where the most gain reduction takes place.

Note as well that the CA3080/LM3080 is not well known for its ability to handle hot input signals, compared to some other chips.  Here is Jim Patchell's comparison of the CA3280 and 3080: http://www.oldcrows.net/~patchell/archives/ca3280_2.html  If you look at the article on page 6 here - http://hammer.ampage.org/files/Device1-8.PDF - you'll see that the 3080 is being used for a voltage-controlled distortion unit.  This is NOT a "clean" chip except for some highly restrictive circumstances.

So, the readiness with which the CA3080 can inject harmonic content NOT found in the original, when pushed hard, plus the tendency of the compression process itself to subtract harmonic content found in the original, can result in a sound that some find a little artificial.  These are both reasons why some folks feel that optical compressors (LDRs will introduce no distortion), or compressors with much higher quality OTAs/VCAs (such as the THAT module found in the CS-3) are preferable, and why some folks like to have just a little clean signal (at least the high end) mixed in with compressed signal.  These two differences ahouls keep the "bite" in, and keep the harshness out.
Title: Re: Keeley compressor clone
Post by: markm on September 25, 2006, 01:31:18 PM
Q1 is the input transistor.  Q2 is the phase-splitter/output transistor.  Using a high-gain/low-noise for these two devices is helpful.

Q3 and Q4 can be cheap "garden variety" 2N3904 types that don't have to be anything other than within spitting distance of each other since they only carry control signal, not audio signal.  Matching them is not counterproductive, per se, but as some have wisely pointed out potentially a waste of effort given tolerances in other components.  So at least make sure you don't have one with hfe=124 and the other with hfe=840.  Q5 sums them and feeds the current-control line on the 3080.  Again, not an audio signal carrier, so hiss potential not that big an issue as near as I can tell.  However, it does supply the current that controls the gain of the 3080, so I gather higher-gain units are preferable here.

I will happily defer to others with more knowledge of transistors (which is a VERY large group of people).  I'm just telling yu what I used and what the different devices do.

Many thanks Mark a dozen times over!
Appreciate the help you always offer  :)
Title: Re: Keeley compressor clone
Post by: Gilles C on September 25, 2006, 03:55:45 PM

Edit - I couldn't get rid of the itallics.. ?

CTRL-I controls it.

I had the same problem when I was hitting "CTRL-I" instead of "Shift-I" until I realised what I was doing...

Gilles
Title: Re: Keeley compressor clone
Post by: davph30 on October 01, 2006, 12:34:37 PM
Still waiting on some parts arriving hope to have the basics together by the end of the week and will let u all know how i get on.

Anyone got any other mods or ideas. A keeley schematic would be great

anyone got a keeley compressor and would like to mail me the layout?

Thanks again

Dave
Title: Re: Keeley compressor clone
Post by: markm on October 01, 2006, 12:36:08 PM
I think we'd all love to get a look at that.  :D
Title: Re: Keeley compressor clone
Post by: davph30 on October 01, 2006, 12:40:43 PM
I know Mark someone must have one they can pull apart, my pedals usually get taken apart the first week
Title: Re: Keeley compressor clone
Post by: nag hammadi on October 01, 2006, 01:40:11 PM
Howdy!
Sent you a PM (after I figured out how to do one  ???  ;D  )
The variable recovery or attack control, etc.  Those are things I got from the CP9 by Ibanez I had from living in West Germany, along with my Aria Pro ;-) .  Slightly interesting story, several years ago, really wish I knew when, I started doing them when a humbucker customer was going to return a pedal.  I wanted to figure out why they were having poor tone/performance, distortions, etc.  So I would do some 'back them',  again don't remember how many years ago.  I did experiment with different versions and found out that I didn't like the exact copy of the Ibanez one and that on some of the keeley comps it just plain didn't work because of significant distortion. So, I ended up finding out that the transistors I was using were different (duh!) and that I had to simply crack out the books and find out 'where they wanted to be' without distortion.
Sure, there was that cap mistake on the schematic and things to make sure were matched, that was the best part of the beginning of the ROSS CLONE ERA, people would send me their compressors that they bought from somebody and I would find just a simple copy of the schematic built, easy fix.
I also did tweak/diddle-stick/calculate/alter just about every part in the unit....just so that I had a decent understanding of it.
I have built them with different IC's, different rectifier circuits, build different input and output buffers for a variety of uses and to match other signals equipment (including one for a TV audio circuit/speaker....don't you just hate LOUD commercials, etc...
In this Late 2006 time frame, RoHS compliant matters force a change.  We are nearly complaint to the letter of the law on about 85% of our product line, so to be analyzed more strictly and technically.  So a true clone to Europe is not legal at all anymore.  At least that is my best understanding.
Take care folks,
Yes, decaf ain't to bad an idea....  :-[

Robert

that's funny - my wife and i have been talking about a compressor to get rid of the stoooopidly loud commercial thing.  MAN that bugs me.

also - let's here it for the aria pro II phase shifter!  the first pedal i got (in 8th grade - what, 20 years ago???), and i used it on every gig up until i built mine.

and just as a side note...

i build pedals for the customers in the shop in which i work.  they ask me if i "invented" any of the stuff.  the best way i have found to describe the majority of the DIY for $ scene is "i am not re-inventing the wheel, i am just making a REALLY good one".

good luck to everyone.  let's face it - the market is WAY large enough to support any of us who are willing to make a living from it.  the mustang belongs to ford, but there are MILLIONS of guys who know it inside and out enough to fix, modify, or reproduce it.  and they make a living from it.

good luck everyone. 
Title: Re: Keeley compressor clone
Post by: davph30 on October 08, 2006, 05:43:39 PM
Got the pedal built today using the tonepad schematic but am not pleased with the sound. When the pedel is on the output level is much lower than my bypassed signal until the level pot is at about 3 oclock and lacking treble.

The only differences to the values are

the output cap is 0.047 instead of 0.05

MPSA18's instead of 5088's

and i didnt have a 50k pot so i put a resistor across a 100K whick gave me a 51.2K

any ideas guys??

Thank you

Dave
Title: Re: Keeley compressor clone
Post by: davph30 on October 09, 2006, 05:44:09 PM
I have increased the volume by removing the resistor across the level pot 100k pot sounds better, but am still getting quite a lot of tone sucking and am having no luck getting more treble
Title: Re: Keeley compressor clone
Post by: Jay Doyle on October 09, 2006, 06:03:58 PM
All compressors tend to suck treble. Nature of the beast unfortunately.

A couple of things you might try though: be sure that the first cap the signal sees, the cap to ground is 220 pF, if it is .0022uF like in R.G.'s schem it will suck treble. If it is already 220 pF try removing it and see if you like it that way. Otherwise you can try lowering the value of the cap right after the 3080, the one parallel to the 150k resistor.

Remove the 10k in series with the output pot for a little more output.

Is the 100k you are using log or linear taper?
Title: Re: Keeley compressor clone
Post by: Jay Doyle on October 09, 2006, 06:05:20 PM
I forgot to add, be sure to keep SOME type of cap in parallel with the 150k resistor after the 3080, it helps to stabilize the 3080.
Title: Re: Keeley compressor clone
Post by: davph30 on October 09, 2006, 06:24:41 PM
Thanks Jay, I have already removed the 220pf. the The 100k is log

with thanks Dave
Title: Re: Keeley compressor clone
Post by: davebungo on October 09, 2006, 07:02:28 PM
ways to achieve less high frequency loss:

a) slow down the attack time of the compressor - transients will not be so harshly treated,
b) decrease the compression ratio,
c) increase the threshold (or gain/sensitivity as on my MXR limiter),
d) put some low pass filtering on the input to the sidechain - as a result, the sidechain will respond less to high frequency content and/or
e) put a little high frequency EQ on the output (although not too much as this may increase noise levels).

remember also that what you may be interpreting as tone sucking is probably/actually a loss of dynamics range which is the function of a compressor in the first place (so ask yourself if that is what you really want).

The best studio compressors are quite often referred to as "transparent", which is just another way of saying that they don't do an awful lot to the signal, or if they do, it is achieved in a more gradual way.
Title: Re: Keeley compressor clone
Post by: markm on October 09, 2006, 08:08:05 PM
In my experiences with compressors, if a guitar player is the type that dimes the controls on the guitar and doesn't use them for the tools that they truly are, more often then not, they will not be happy with a compressor. If on the other hand, one backs off the volume a tad and changes the signal level going into the comp, the two (guitar and comp) can work quite well together.
Usually the "tone-suck" complaints are by people who don't use the guitar's controls at all.
Beleive me, back off the volume a bit and use the two together as one instrument. Makes a difference to me anyway.
This is just my opinion however.  :icon_neutral:
Title: Re: Keeley compressor clone
Post by: davph30 on October 10, 2006, 05:52:28 PM
I've tried everything I can think or and u have suggested , still no luck :icon_redface:

i am getting a muddier sound than i expected no distortion or noise even when both controls are maxed.sustain and volume still has to be at about 3 o clock before its louder than the bypassed signal.

Im lost I have swapped all transistors and the 3080.

Any ideas?
Title: Re: Keeley compressor clone
Post by: Jay Doyle on October 10, 2006, 06:04:41 PM
Have you ever tried an actual Keeley or Ross? I ask only because you just simply may not like the sound of it. Maybe someone else can check the level at which the output exceeds the bypass but this comp isn't really meant to be a booster.

You just may not like the effect itself, unfortunately. It sounds like you have done everything possible. I don't remember the beginning of this thread. You checked to make sure the trim was set properly? You get a change in the sound when you rotate it?
Title: Re: Keeley compressor clone
Post by: davph30 on October 10, 2006, 06:42:32 PM
I have checked the sound against the samples here http://www.steelbender.com/spotlightkeeleycomp.html and my pedal is much muddier against the setting used
Title: Re: Keeley compressor clone
Post by: davph30 on October 10, 2006, 06:45:48 PM
Hi Jay

when i adjust the 2k trim i adjusted it to the centre it gets gated either side of this between about 11 o clock and 2 oclock
Title: Re: Keeley compressor clone
Post by: petemoore on October 10, 2006, 06:55:54 PM
  To let the volume control be set at a lower level and have the same or more highs, a small cap across it's input/wiper lets highs through...
  When the volume is decreased, resistance across the two lugs mentioned increases, this probably doesn't muddy it up much [?], but it's an opportune place to use a small cap to get a treble enhancement.
  A fixed R/C parallel affair, in the signal path just before the volume pot could be used, however this would also attenuate some signal
Title: Re: Keeley compressor clone
Post by: markm on October 10, 2006, 08:51:07 PM
The volume issue seems strange 'cause my Dynaclone and Ross comp can get quite loud on their own with no problem.
This circuit also is more single-coil friendly in my opinion as 'buckers seem a bit too dark for it sometimes.
Title: Re: Keeley compressor clone
Post by: RobertKeeley on October 11, 2006, 12:42:44 AM
Hi Jay

when i adjust the 2k trim i adjusted it to the centre it gets gated either side of this between about 11 o clock and 2 oclock

This MAY be a clue as to what is wrong.  I've found in MANY (all even?!?!) cases that you can hardly notice a difference to the sound even when adjusting that trim pot quite a bit from one extreme to the other...sure at the very ends, there will be a problem... but in general I think I've noticed much more play "allowed" before 11 oclock and 2 oclock.  So if it only works at the noon position but no where else, this is an indication that something may be wrong.  I've seen it before a bunch as we've built them...but I honestly can't remember what now...except that it was a part (resistor or cap) that is wrong.  For example a 15K where a 150K should be, etc, etc... IF you built the board, check that of course again.
Funny that you mention changing the transistors and chip... I have to beat my techs up on that subject... YOU DON'T ALWAYS START BY CHANGING THE THING WITH THE MOST LEGS ON IT!!!!  ;D ;D ;D
LOL
I undertand, trust me, that is how I started many, many a broken device! ;)
Robert

ps, I'll check a comp tomorrow and see what the play is in the 2k trimmer.  I bet it is pretty large if memory serves.
ps again...yes, the MPSA18 were chosen because of high gain.   ;)  I still think I could do better on the 'ultimate' transistor selection, just haven't gotten back to that idea yet!

rk
Title: Re: Keeley compressor clone
Post by: R.G. on October 11, 2006, 09:06:21 AM
The 2K trimmer is substantially useless. It can be effectively replaced by two 1K resistors.

The 2K trimmer was put in there to balance the two inputs to the 3080. This was back when all semiconductors, the 3080 included, were worse than they are today. It's only purpose is to keep the gain signal on pin 5 from feeding through to the output by nulling it out in the first diffamp pair inside the 3080. Modern 3080's don't usually need it.

Having a trimmer there for an uninformed DIY effects maker is an unendurable temptation to tweak it and then to worry when it's right. Set it to the middle and ignore it, or replace it by two 1K's - or tweak it infinitely until it's somehow more perfect to your ears.

The 3080 has a flat response well up into the MHz region. Treble loss is not coming from the 3080. The treble is deliberately rolled off at a couple of places in the circuit. Go there.

One of the worst problems with the Dynacomp and the Ross copy of it is that the same emitter follower which runs the gain feedback loop also runs the audio output. This was done to keep the thing simple, but it represents a conflict of interest for that transistor. It can't really do a good job of both at the same time - it's a compromise. The higher the current gain of that transistor, the better it does, which is why the 5088/5089/A18 series with their very high current gains produce better results. They isolate the high impedance 3080 output from the losses on the envelope detection side better. But using a separate audio output and envelope driver would work better yet.

In the end, it's not the semiconductors or the passives that are the problem, it's the design compromises that limit you.
Title: Re: Keeley compressor clone
Post by: puretube on October 11, 2006, 01:06:30 PM
been biting my tongue on that one...  :icon_redface: - tnx for explaining that, R.G.  :icon_smile:
Title: Re: Keeley compressor clone
Post by: vanhansen on October 11, 2006, 01:28:27 PM
Great thread here.  I've been wanting to build a compressor for a while, or purchase one, and just couldn't see myself doing so because every compressor I ever tried out I couldn't make work for me.  That changed last year at the Arlington Guitar Show.  I tried out Keeley's Compressor and was floored.  It's the only compressor that I actually liked out of all the ones I've tried.  I'd love to snag one this year.  Who knows, maybe there will be some show specials.  ;)  And Robert is a really nice guy.  He took time out of the craziness at the booth (and it was crazy) to say hi and talk for a little bit.  I'll be visiting the booth this year if he's there.

Right now, the idea of building one is a little intimidating.  My DIY hobby has been on the backburner so I'm still working with overdrives and distortions.  :'(  Hopefully I can dedicate more time to it soon but in the meantime, it's changing up what I have done and buying what I'd like to have.
Title: Re: Keeley compressor clone
Post by: davph30 on October 11, 2006, 06:21:07 PM
Good news!!!
I've found the problem, the 100k pot was faulty if i pressed on the connection with a screw driver the sound brightened up and gave me much more play on the 2k pot, can now adjustit between 9 and 3 o'clock without the sound gating.
Title: Re: Keeley compressor clone
Post by: RobertKeeley on October 12, 2006, 04:28:06 AM
We stopped using the 2k trimmer a long time ago.  There was no need for it.  Look at our pedals that were produced late 2005 I think.
The gain of the transistors solved many problems, so that was an easy transistion.  I still think I might be able to find a better selection of transistors.  I think working on the input buffer and other parts of that stage would be a productive thing.
Yes, there are many things you can do to that circuit to make it better... the first thing is anything better than the 3080.
Thanks
Robert
Title: Re: Keeley compressor clone
Post by: Dirk_Hendrik on October 12, 2006, 05:03:04 AM
Modern 3080's don't usually need it.

Hmm RG, You might want to reconsider this:
http://www.till.com/blog/archives/2005/06/last_of_the_ota.html (http://www.till.com/blog/archives/2005/06/last_of_the_ota.html)
Title: Re: Keeley compressor clone
Post by: R.G. on October 12, 2006, 09:41:21 AM
I'm aware of that.

In this case "modern" means "the ones still not used in something and available for builds".

The Dynacomp was designed when the 3080 was still new and when the fabs could just barely build them. There is a continuous tweaking process at every fab to make them run better. The last-produced 3080's - and every chip, for that matter - are or can be better, faster, lower noise, higher performance etc.

I have real world experience with my statement. The trimmer is unnecessary for the Dynacomp circuit.

Don's comments about making a discrete OTA are well founded. I posted about this some ways back. You can make up an OK-ish OTA if you can just get monolithic dual transistors. You need a well matched pair for the input diffamp, and then modestly matched ones for the current mirrors.
Title: Re: Keeley compressor clone
Post by: puretube on October 12, 2006, 10:01:17 AM
http://www.nxp.com/acrobat_download/datasheets/BCV61_3.pdf
Title: Re: Keeley compressor clone
Post by: R.G. on October 12, 2006, 10:56:31 AM
Yep, those and the complements will do nicely for the current mirrors. Do they make a monolithic matched diffamp?
Title: Re: Keeley compressor clone
Post by: Jay Doyle on October 12, 2006, 11:16:06 AM
Yep, those and the complements will do nicely for the current mirrors. Do they make a monolithic matched diffamp?
I actually was able to design a pretty good replica of the3080 using a CA3086 chip which has a diffamp and four other matched transistors on the chip.

Unfortunately, it was discontinued along with the rest of the CAxxxx line...  :icon_mad:
Title: Re: Keeley compressor clone
Post by: analogmike on October 12, 2006, 11:40:40 AM
>> The 2K trimmer is substantially useless. It can be effectively replaced by two 1K resistors.

Functionally correct, this will always work with any of the CA3080E chips we have used, we have resistor areas on our boards for doing so.

>> This MAY be a clue as to what is wrong.  I've found in MANY (all even?!?!) cases that you can hardly notice a difference to the sound even when adjusting that trim pot quite a bit from one extreme to the other...sure at the very ends, there will be a problem... but in general I think I've noticed much more play "allowed" before 11 oclock and 2 oclock.  So if it only works at the noon position but no where else, this is an indication that something may be wrong. <<

No, this is why we keep the 2K BIAS trim pot in our pedals. Turn up the sustain and the ambient sound will die out at about 1/8 turn of the trimpot either direction away from 12:00. That is how we calibrate them, and this feature is usefulfor debugging sick pedals.

have fun!
Title: Re: Keeley compressor clone
Post by: puretube on October 12, 2006, 01:12:56 PM
Yep, those and the complements will do nicely for the current mirrors. Do they make a monolithic matched diffamp?

dunno `bout "matched",
but various companies make duals (2xNPN; 2xPNP; 1xP/1xN) on a die
in SOT-cases...
 :icon_wink:
Title: Re: Keeley compressor clone
Post by: Jay Doyle on October 12, 2006, 01:37:54 PM
dunno `bout "matched",
I always thought, perhaps incorrectly, that when the transistors were grown on the same die that they were matched by default. I thought this was the purpose of putting them in the same die/package.
Title: Re: Keeley compressor clone
Post by: puretube on October 12, 2006, 01:57:39 PM
they`ll be close - closer than 2 individuals - also: thermally identical -
but: not "trimmed to match" by purpose.

(= close, but no cigar...  :icon_smile: )
Title: Re: Keeley compressor clone
Post by: StephenGiles on October 12, 2006, 02:00:06 PM
Oh that life was so simple!
Title: Re: Keeley compressor clone
Post by: Jay Doyle on October 12, 2006, 02:06:21 PM
they`ll be close - closer than 2 individuals - also: thermally identical -
but: not "trimmed to match" by purpose.

(= close, but no cigar...  :icon_smile: )
That's it, I was thinking thermally matched. I guess they would be close enough though...
Title: Re: Keeley compressor clone
Post by: davph30 on October 12, 2006, 02:26:56 PM
Panasonic list the 2sc3311A as an alternative to 2sc1849 has anyone tried or lookied into it?
Title: Re: Keeley compressor clone
Post by: RobertKeeley on October 13, 2006, 05:42:55 AM
Turn up the sustain and the ambient sound will die out at about 1/8 turn of the trimpot either direction away from 12:00. That is how we calibrate them, and this feature is useful for debugging sick pedals.

have fun!

mmmkay....
Title: Re: Keeley compressor clone
Post by: Hiwatt25 on October 13, 2006, 08:21:37 PM
What's that meant to mean Bob?
Title: Re: Keeley compressor clone
Post by: Jay Doyle on October 14, 2006, 06:17:13 PM
What's that meant to mean Bob?
I think it means that he doesn't understand what analogman is saying, or questioning that AM's procedure may not be the best. To me this sounds like a continuation of the bloviating of above.

BUT, AM's procedure makes complete sense to me and follows the same procedure I always recommed for setting the trim: Turn the trim until you hear the MOST noise. At about 1/8th of a turn away from the 'MOST noise' portion of the trim, the + and - inputs become unbalanced and the sound cuts out completely; until you hit it with a signal that brings it back through the balanced portion. And this is why it sounds gated when the trim is not set correctly.

Jay Doyle
Title: Re: Keeley compressor clone
Post by: markm on October 14, 2006, 08:08:37 PM
What's that meant to mean Bob?
I think it means that he doesn't understand what analogman is saying, or questioning that AM's procedure may not be the best. To me this sounds like a continuation of the bloviating of above.

*sigh*
The saga continues.....I'm awaiting for the ring of the bell on monday morning and round 3 to begin....or would that be four?  :icon_confused:
Title: Re: Keeley compressor clone
Post by: RobertKeeley on October 15, 2006, 04:00:12 PM
What's that meant to mean Bob?
I think it means that he doesn't understand what analogman is saying, or questioning that AM's procedure may not be the best. To me this sounds like a continuation of the bloviating of above.

BUT, AM's procedure makes complete sense to me and follows the same procedure I always recommed for setting the trim: Turn the trim until you hear the MOST noise. At about 1/8th of a turn away from the 'MOST noise' portion of the trim, the + and - inputs become unbalanced and the sound cuts out completely; until you hit it with a signal that brings it back through the balanced portion. And this is why it sounds gated when the trim is not set correctly.

Jay Doyle


That is a valid method for doing it by ear for sure.  We did something very close to that for years.
Using modern CA3080E devices by Harris and 1% tolerance resistors has made it a worthwhile change to our version of the circuit (leaving out the 2K trimmer).
Now people don't adjust it thinking that it is an attack control!!!  SO, it is a much better feature to NOT have it in terms of customer service and mistakes that people may make by trying to adjust it.  You want to leave out as many trimmers as possible in designs right?!?!?!?  The Bean Counter gets mad when he/she looks at the bottom line (parts and labor to have a trimmer).
 ;D
Take care folks and have a great weekend,
Robert
Title: Re: Keeley compressor clone
Post by: davph30 on October 15, 2006, 04:36:06 PM
Hi guys just to let u know everything is working great now.

I used the tonepad schematic and only changed the transistors to MPSA18's which produced less noise but not that noticabe.

Thanks for all your help

Dave
Title: Re: Keeley compressor clone
Post by: Jay Doyle on October 15, 2006, 06:00:47 PM
That is a valid method for doing it by ear for sure.  We did something very close to that for years.
Using modern CA3080E devices by Harris and 1% tolerance resistors has made it a worthwhile change to our version of the circuit (leaving out the 2K trimmer).
Now people don't adjust it thinking that it is an attack control!!!  SO, it is a much better feature to NOT have it in terms of customer service and mistakes that people may make by trying to adjust it.  You want to leave out as many trimmers as possible in designs right?!?!?!?  The Bean Counter gets mad when he/she looks at the bottom line (parts and labor to have a trimmer).
 ;D
Take care folks and have a great weekend,
Robert
Great point, I wouldn't have ever thought of it like that, having to design for people who may mess with the trimmers thinking they are something that they are not! Guess that is the difference between building for yourself and building for the masses.

I don't think of it in the commercial/"have to sell it sense"

Jay Doyle
Title: Re: Keeley compressor clone
Post by: markm on October 15, 2006, 06:09:21 PM
I have some of the Harris 3080's and find them all consistant.