DIYstompboxes.com

DIY Stompboxes => Building your own stompbox => Topic started by: Fp-www.Tonepad.com on June 14, 2005, 02:42:34 PM

Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 14, 2005, 02:42:34 PM
New project:

http://www.tonepad.com/project.asp?id=50

I will need some of the experienced builders (Mark comes to mind) to check this adaptation of the Maestro FS1 using LM13600 otas and including Tonda's mods.

Fp
Title: Maestro Filter Sample and Hold
Post by: Bill Bergman on June 14, 2005, 02:58:19 PM
Cool!! Wish I didn't already have one...... although it only the 2 knob model.
Title: Maestro Filter Sample and Hold
Post by: Ry on June 14, 2005, 03:38:11 PM
Dang, I built one from the GGG site too.  I may have to build this one just to see if it sounds any different.  I really love this pedal.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 14, 2005, 03:40:56 PM
Please DO :)

And report back. As I said, not only is the layout not verified, but the circuit uses different chips and adds a bunch of mods.

I've checked it out many times and haven't found errors... but then again... who knows.

Fp
Title: Maestro Filter Sample and Hold
Post by: StephenGiles on June 14, 2005, 04:53:58 PM
Hi Francisco - buenos tardes, correct me if I'm wrong but the filter section is a normal triggered filter? If so what is the ripple like in the control voltage?
Stephen
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 14, 2005, 05:09:33 PM
Stephen,

Look at the DPDT switch that selects between filter and s/h modes:

the "A" spdt biases the pnp transistor. (when in s/h mod you set it with the trimpot)

the "B" spdt selects the source for the CV from the envelope detector (highly modified by Tonda to include direction, attack and decay) and the sample and hold which is the noise and LFO.

So, to my understanding, the filter section (made with the two otas and surrounding parts) is a band pass filter, controlled by the CV. So yeah, I would say it's a normal triggered filter.

This brings us to the next experimentation: since the circuit blocks are so well defined, one could use other CV filters (or anything CV controlled), or use other CV sources to control the filter. (manual control for example)
 
Fp
Title: Maestro Filter Sample and Hold
Post by: moosapotamus on June 14, 2005, 07:05:06 PM
Wow, that looks great, Fp! Beautiful work, as always.
I just might have to build myself another, too. 8)

~ Charlie
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 14, 2005, 07:26:40 PM
HEY CHARLIE!

Remember how long it was when we started working on this!!?

What? two years??

Fp
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 14, 2005, 07:52:44 PM
why there are two transistor join together after the input stage?
why is Q4 missing ?
the mark '9' '10' at the transistors near the input stage meaning what?
Title: Maestro Filter Sample and Hold
Post by: moosapotamus on June 15, 2005, 12:29:20 AM
Quote from: Fp-www.Tonepad.com
What? two years??

What? ohmygod. That long, really? :shock:
Wow, I'm almost as fast as you at finishing up projects. :lol:

Thanks 8)
~ Charlie
Title: Maestro Filter Sample and Hold
Post by: Ry on June 15, 2005, 12:47:18 AM
I might have to give it a go.  I have yet to etch a board, though...this may not be my best bet as a first try!  I will report back if I get up the courage to try it out.

Ry
Title: Maestro Filter Sample and Hold
Post by: Transmogrifox on June 15, 2005, 02:56:32 AM
Quote from: wui223
why there are two transistor join together after the input stage?
why is Q4 missing ?
the mark '9' '10' at the transistors near the input stage meaning what?


a)  This is called a darlington connection.  Using transistors like this significantly increases the input impedance.  The late Crybabies use the darlington input transistor.

b) I don't know why Q4 got skipped, but it may have been something present early in the design that had been determined to be unecessary and was removed, and it was easier not to rename everything else after the layout had been finished.

c) The LM13600 IC chip includes a darlington transistor built-in which is used as a buffer for OTA's, in fact, it is designed to be used how those JFETs are used.  It must have been determined by the designer that the filter had a warmer tone using FETs instead of the built in darlingtons.

Since the darlington pins would otherwise be useless, why add another seperate transistor to the design?  Simply use the extra unused transistor for an input buffer.

The short answer is this:  Pins 9 and 10 refer to the base and emitter of the darlington built in to the OTA chip.
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 15, 2005, 03:21:22 AM
thanks i check out the datasheet and give me the same explanation. but can i ask why the MAX1044 usage in Geofx differ from tonepad's schematic? the Geofx use two caps and tonepad use one only.
geofx connect pin2 to 4 by a 10uF cap but tonepad ground the cap and ground the pin 4 as well.
Can someone explain this, which one is right?
In fact i built this effect before but i didnt works, i wonder why
Title: Maestro Filter Sample and Hold
Post by: Joe Viau on June 15, 2005, 09:29:45 AM
Also, R. G. had a schematic for a CMOS pseudo-random generator on his site:

http://www.geofex.com/FX_images/pseudorandom2.pdf

Has anyone tried this with the old S/H and is anyone planning on trying it with the new revision? I've read threads about how persnickety the noise transistor is.  I have schematics for an ARP 2600, and I may look to see how that synth did its noise source.  It had pretty good S/H, too.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 15, 2005, 10:26:55 AM
Transmogrifox got it right.

I'll re-check the max1044 part of the ckt.

Fp
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 15, 2005, 05:51:10 PM
i think the one in tonepad is right coz i try the connection shown in schematic, and i get -9V from pin5. But i use a 7660 instead of MAX1044
How to choose for the noisy transistor? i couldnt get one that is working right. For the FET can i simlpy use any FET like 2N5458?
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 15, 2005, 05:54:43 PM
Wui,

I just checked and it does match the schem at geofex. It's correct.

You can use the 2N5458, just make sure the pinout matches the pads of the layout.

About the noisy transistor, get a few 2n2222 or nte123ap and use a socket to try different ones.

Fp
Title: Noise transistor
Post by: soggybag on June 15, 2005, 06:16:11 PM
I made the FSH from the layout at uStomp. I used 2N3904 for the noise transistor. I hooked my scope to the noise opamp that amplfies the noise and tested a handfull of transistors until I found one that worked well.

I remember reading a few posts, as I was building mine, where people had tried several different varieties of transistor.

I'm a total novice, but if I understand what's going on the only two leads of the transistor are used and it is acting like a revese biased diode. So I would guess that you might even be able to use a diode here.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 15, 2005, 06:49:28 PM
I remember RG once said something about transistors becoming more noisy after being biased in a certain way... maybe it's time to search the archives. Perhaps we can make a noisy transistor noisier.

Fp
Title: Maestro Filter Sample and Hold
Post by: LP Hovercraft on June 15, 2005, 10:58:09 PM
Good work FP!  On a previous thread I saw somebody mention that a leaky NPN germanium like a not-so-to-spec NTE101 might do the trick.  I'd be curious to see if anybody has tried it.  As for this layout, this makes a lot more sense to me than a bunch of icky 741's and the now "obsolete" CA3080.  Though I'm in the middle of perfboarding the GGG version,  I'm sure I'll make another using this version eventually. :)
Title: Maestro Filter Sample and Hold
Post by: Ry on June 15, 2005, 11:39:46 PM
I have tried a boatload of different transistors for the noise source (including a couple bad ge's) and have always come back to a dirt cheap surplus 2N2222, with a 2n3904 being a close second.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 16, 2005, 02:06:56 AM
LP, thanks!

Ry, I think the 2n2222 is quite noisy, I wonder if it can be made noisier by biasing it wrong for a while (in another circuit designed for that purpose) and then put it in the FSH1

Fp
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 16, 2005, 03:20:40 AM
I check out the store at my place and couldnt find a single piece of LM13600.
I think the circuit will work right. Coz the CA3080 which is single OTA is replace by a Dual OTA as suggested by Tonepad's designer.
And the single op-amps are replace by a dual op-amp. Others remain the same so there is no way it couldnt work unless soldering error or part failures.
Anyway mine still dont work and i wonder why
Title: Maestro Filter Sample and Hold
Post by: Zero the hero on June 16, 2005, 07:41:42 AM
Good job FP!
I always have to learn from you!

There was a post and we discussed about the differences between LM13600 and LM13700. Does it work with lm13700 too? Any difference in the sound?
Actually I have no time to build it and test by myself...
Title: Maestro Filter Sample and Hold
Post by: Paul Perry (Frostwave) on June 16, 2005, 10:24:21 AM
Quote from: Zero the hero
There was a post and we discussed about the differences between LM13600 and LM13700. Does it work with lm13700 too? Any difference in the sound?...


I havn't tried, but I'm sure a LM13700 or NE5517 would be fine. Or the Japanese 13600 or 13700 for that matter.

As for the person who asked about using a 'normal' diode, that won't work, you are relying on the diode sructure to undergo zener breakdown I think. Which a transistor might, but not a 1N4148 for example.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 16, 2005, 11:50:44 AM
I didn't see that thread. But looking at the data sheet I don't see why not use either LM13600 or LM13700.

Fp
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 17, 2005, 10:20:28 AM
can someone help me coz i spend endless hours on this project but still fail
The filter is not working same as sample/hold.
I just can hear noise and constant "du du" sound. Why?
How to fix it? I use 2N5458 for FETS and a BC184 for the first FET ar input stage. Else is CA3080 and LM741. I really need help
Title: Maestro Filter Sample and Hold
Post by: Ry on June 17, 2005, 11:27:39 AM
Wui,

Just to clarify, does the filter setting work, but not the sample/hold?

Have you tried slowly adjusting the trimmer while listening to something constantly playing through the pedal (could be a cd player or anything, really) to see if you need to tune the noise in?

What are you using for a noise source and have you tried other transistors?

Ry
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 17, 2005, 04:35:33 PM
i try both 2N3094 and 2N2222A, how is the sound of working filter? i really cant hear an effect only noise
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 17, 2005, 05:08:26 PM
It's worth to mention that Mr. Wui is NOT building from the schematic I posted but from JD Sleep's schematic. He is also using perfboard.

Good luck with your project mr wui.

Fp
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 17, 2005, 06:50:12 PM
yes u are right. But what is the point the schematic is not much different only some part change so the concept still apply. And i am pretty sure my connection is done properly coz i redo the whole thing on a new board.
Title: Tonepad FSH 1
Post by: soggybag on June 18, 2005, 12:34:13 PM
I couldn't resist making another one. I think I had most if not all of the parts. I made the PCB yesterday and solder a majority of the parts.

(http://webdevils.com/stompbox/IMG_3087.JPG)
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 18, 2005, 12:54:31 PM
Great!

NOW we're talking!

I hope it works  :!:
Title: Maestro Filter Sample and Hold
Post by: Ry on June 18, 2005, 06:53:54 PM
I etched a board yesterday, and it worked like a charm (my first etch)!  Thanks for the photo essays about creating a board using PNP, FP.  Now I just need to drill it and populate it.  I will post back when I get it done and compare it to the old version.
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 18, 2005, 07:19:31 PM
So Ry u have done a working version right? then what is the problem why i cant get it sound right i am really desperately need it
Title: Maestro Filter Sample and Hold
Post by: moosapotamus on June 18, 2005, 08:07:52 PM
wui -

perfboard = 1,000,000 opportunities to make a simple mistake that could take a long,long,long time to discover... especially when dealing with this level of complexity.

We have all been there, myself included... some blindingly simple wiring or connection error that you could kick yourself for once you discover it. The difficulty is discovering it.

You obviously have all the parts. If you can't run down the mistake(s) that are keeping your circuit from working, the only suggestion left is to try a verified PCB layout that follows the same schematic that many others here have had success with.

~ Charlie
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 18, 2005, 11:42:32 PM
Thanks for all of ur suggestions just that i cant make the PCB in an easy way, i dont haev access to press'n peel blues. Anyway the FET is choose shouldnt be problem right? Just the noise transistor, anyone got way to choose it to work?
Title: FSH 1 problems
Post by: soggybag on June 18, 2005, 11:53:06 PM
You should use the search above to search the forum for this effect. There has been plenty of talk about the FSH-1. I built one myself and it didn't work at first. The filter sweep mode still doesn't work correctly, though the Sample and hold mode is working.

I would not build a new one yet I think I would keep trying to get the first to work. Try tracing your circuit with an audio probe. If you figure out where the audio stops it might point to a problem.

If the sample and hold is not working. Try tracing the LFO. If you hear a ticking turn the speed knob to see if changes speed. Use your audio probe to check the noise. The noise should come out at one of the legs of the FET in the Sample and hold. Another leg of this FET should also be getting the LFO signal. If you have a scope you should scope all of these places. If not probe with the audio probe.
Title: Maestro Filter Sample and Hold
Post by: markr04 on June 19, 2005, 01:02:35 AM
Quote from: wui223
Thanks for all of ur suggestions just that i cant make the PCB in an easy way, i dont haev access to press'n peel blues. Anyway the FET is choose shouldnt be problem right? Just the noise transistor, anyone got way to choose it to work?


A laser printer and inkjet photo paper works quite well. I've done 20+ PCBs this way. PM me if you want more info.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 19, 2005, 11:28:26 AM
... and that's what "hijacking a thread" is all about... I hope the guys that are building from my layout come back with a report.

Fp
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 19, 2005, 12:10:54 PM
I want to try ur layout also but i just cant get the Dual OTA chip
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 19, 2005, 12:13:17 PM
wui, No offense, but I don't think you're qualified for this level of project. If you were building on a pcb I would think you'd have a chance, on perfboard, I just think you have too little chance of success.

Why don't you start another thread for troubleshooting your build and leave this one for those who are building the new circuit.

Fp
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 20, 2005, 12:59:09 PM
Soggy, Ry, Updates?

Fp
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 20, 2005, 01:00:53 PM
Duplicate post.
Title: FSH 1 progress
Post by: soggybag on June 20, 2005, 01:21:04 PM
Still working Fathers day and work have taken some time away from work in the "lab". Maybe I'll have a chance to finish up up later this week...
Title: Maestro Filter Sample and Hold
Post by: Ry on June 20, 2005, 03:19:29 PM
I haven't gotten the board drilled or populated yet.  I had a busy weekend and only got the board done on Friday because I had the day off and there was no one around to distract me.  I have a very active outdoor life and my wife and I have about two months to safely do canyoneering trips here in Arizona before the summer rains start, and believe me, you don't want to be in a technical (involving climbing, swimming and rappeling) canyon when it starts raining!

I will hopefully get the board drilled tonight and start populating it.

Ry
Title: FSH 1 tonepad
Post by: soggybag on June 23, 2005, 01:54:15 PM
I have my board populated and all of the jacks and pots wired up. I tried to fire it up this morning. I only put in the MAX 1044 to test the voltages. But ran into a problem when the MAX 1044 started to get really hot.

I will have to find some time after work to take a closer look...
Title: Maestro Filter Sample and Hold
Post by: Ry on June 23, 2005, 02:37:28 PM
I've got my board populated except for the pots, jacks and switches.  I will hopefully get the rest of it wired up tonight and see what happens when I apply power.

I did notice that there appears to be a connection missing on the Range pot lug 3.  It should be connected to the junction of the 100k and .15uf cap, but there are two pads interrupting the trace...I think.

I will make sure to check over the 1044 section prior to powering it on, though.  I used my last 1044 on this project.

Ry
Title: FSH 1
Post by: soggybag on June 23, 2005, 03:02:32 PM
I noticed there were two pads in themiddle on the left side of the board that seemed to need a jumper, why I'm not sure, but it looked they should be connect according to the schematic.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 23, 2005, 05:23:51 PM
Soggy,

You're right. I left those there for experimentation.

Fp
Title: Maestro Filter Sample and Hold
Post by: Ry on June 24, 2005, 03:33:34 PM
FP,

I think that the 1044 layout/schematic is incorrect.  Wui made the point that the 10uf cap is going between pin 2 and ground on your layout/schematic might be incorrect, and I think he's right.  It looks like the cap should be going between pins 2 and 4 (thus creating the charge pump action) and not to ground.

The diagram on GEO can be easily interpreted how you did, but check out the data sheet: http://pdfserv.maxim-ic.com/en/ds/ICL7660-MAX1044.pdf

I think that the negative side of the 10uf cap should not be grounded, but rather just connected to pin 4 of the 1044.  This would account for soggy's warm chip.

Ry
Title: Maestro Filter Sample and Hold
Post by: wui223 on June 24, 2005, 05:06:01 PM
Anyway i made the PCB for FSH and decide to substitue the dual OTA with two single OTA, coz i cant get the dual version. In fact everything is just the same. so i will this weekend hopefully overhead Ry and be the first to success in Tonepad layout.  :D
Title: Tonepad FSH-1 fix
Post by: soggybag on June 24, 2005, 11:04:11 PM
You're all right, the negative lead of10u cap needs to connect to pin 4 on the Max1044. I did this and everything seemed power up correctly.

After I tested the voltage coming out to the charge pump I put the rest of the chips and transistors in. I used some BF2457 (I think thats the number) for FETs. I didn't check the pinouts, I just followed the layout (always a recipe for disaster).

I didn't hear anything, so I plugged the guitar into the input and the amp into the output...

But I still didn't hear anything. Then I got hungry, and the the saga will have to wait to be continued...
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 24, 2005, 11:39:46 PM
I have corrected the pdf.

For those who made the pcb, the correction is easy. Just cut the trace from pin4 to ground and the trace from the negative lead of the capacitor to ground. Then connect the cap's negative lead to pin4.

I hope this error didn't fry any MAX1044s.

Fp
Title: Tone pad FSH 1 debug
Post by: soggybag on June 27, 2005, 01:17:41 PM
I didn't have much time this weekend to work. But I applied the audio probe and I seem to be getting the signal through pin 9 of IC1 but the signal diappears after the 22K resister between pin 9 and pin 6 of IC1.

It seems the audio signal gets sucked off into the envelope generator and is gone.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 27, 2005, 01:56:37 PM
Soggy,

pin6 of IC1 is -8vDC there shouldn't be any audio in pin6.

Did you add the jumper between the two orange square pads on the left of the pcb? it was missing from the first revision of the pdf I posted. The envelope generator converts the signal to a control voltage, so the guitar signal is also lost there, the audio probe won't be of help here, an analog DMM is a better tool to see if the envelope generator is working.

Fp
Title: FSH 1 tonepad
Post by: soggybag on June 27, 2005, 02:44:36 PM
My mistake I meant pin 4. I didn't have much time this morning I will have to spend more time testing later this week.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 27, 2005, 08:43:38 PM
Soggy,

From pin9 follow the 0.15uF capacitor, then there's the 100k/3.3k voltage divider going to pin4, that voltage divider lowers the amplitude of the signal a lot.

If you have all the parts in, you should be getting some audio at the output regardless of the control settings, check that you have the FET pinout correct.

Fp
Title: Maestro Filter Sample and Hold
Post by: Ry on June 28, 2005, 10:52:36 PM
We have liftoff!  I got my board all populated and fixed the 1044 traces and it worked immediately.

That said, there is a tremendous high pitch bleed through in both the filter and sample/hold settings that I cannot get rid of.  I played with the trimmers for about an hour with no luck.  If I trim out the noise, I also trim out the filtering.

It's very hard to compare it to the GGG old-style version with this issue, but I noticed that this circuit has a much slower highest setting for the sample/hold.  It's also much, much brighter than the older version.  Any other comparisons are not fair at this point.

Ry
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 29, 2005, 01:18:46 AM
Great!

At least we have something going on, I fear that including all the mods in such small board can have that result (noise), please keep debugging it. I don't know how much is the circuit affected by changing the OTAs...

Let's wait for soggy's results.

:)

Fp
Title: Maestro Filter Sample and Hold
Post by: Ry on June 29, 2005, 09:31:59 AM
I agree that the board size is somewhat to blame.  The GGG layout has a very minor amount of the same bleed through signal, but it isn't too distracting.

I will continue to play around with it.

Thanks for the work that went into this, we'll get the bugs worked out!

Ry
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 29, 2005, 11:05:40 AM
can you make a sound clip and email it to me?

fp AT tonepad (dot you know what).

Fp

ps: SPAM has gone insane in the last few weeks!
Title: Maestro Filter Sample and Hold
Post by: Ry on June 29, 2005, 11:49:35 PM
I will do my best to get a sample to you on Friday.
Title: FSH-1
Post by: soggybag on June 30, 2005, 11:11:04 AM
After flipping the FETs around. The sample and hold effect seems to be working well. The filter sweep mode does not work.

When not playing I hear the sample and hold quietly in the background.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on June 30, 2005, 12:39:42 PM
Cool. Did you wire the sweep direction DPDT switch?

Fp
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 01, 2005, 01:18:31 PM
I have decided to build this one, the pcb is etching right now.

I will build it by blocks, in order to try and find the possible problems/errors.

Fp
Title: FSH-1
Post by: soggybag on July 05, 2005, 01:08:13 AM
After further testing I find

The sample and hold mode is working. But you can here the sample and hold effect in the background when not playing.

The filter mode is working but there is a background hum. I used a 10K pot for attack, didn't have a 5Kon hand, at some settings there is no effect.

What type is the decay pot? There is not much useable range.

The sweep switch seems to only be sweeping down. The up sweep doesn't seem to be working. Could be a problem with the wiring. The wiring on the layout was a little confusing. I will have to check it against the schematic I might have made a mistake here.

Playing on the high strings doesn't seem to generate enough signal to trigger the filter envelope.

I used some a pair of 1458 opamps I had sitting around for a first test. I think I will replace these with some TL072s and test again.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 05, 2005, 11:57:14 AM
I have uploaded the mp3 Ry sent me. Here's the link:

www.tonepad.com/fpstuff/ry-fsh.mp3

The whining is terrible, and very much in audio frequency. Does it change with the speed of the LFO?

Soggy, do you have that same issue?

I believe it could be offboard wiring related too. Does moving the wires going to the s+h/filter change the noise?

Soggy, the envelope detector controls are mods by Tonda, maybe somebody who built using those mods can help with pot taper/etc.

I haven't had a chance to build my own, and it seems like it will be a while until I have the time, still, I am very interested in troubleshooting this one.

Fp
Title: Maestro Filter Sample and Hold
Post by: Ry on July 05, 2005, 12:44:19 PM
Oh, now that's embarassing!  I never thought that my crummy 30 second demo would be online.  Don't get me wrong, I'm not upset, but I would have made it more interesting...

The whine does not change with the lfo speed.  It is very faintly present in my GGG build as well, but only if I listen very, very closely to the S/H setting (it's not at all present in the filter mode).

The whine gets maybe 5% better when I move the in/out wires farther from the board (they tend to run over the entire board right now).  There is no difference in the sound if I move any of the other wires.  

I am planning on wiring up a different filter/s&h switch to see if maybe it is somewhat faulty.

My envelope control mods work.  They are very touchy, especially the decay one as Soggy mentioned.

Soggy, I used TL072's for my op amps and it filters pretty well.  I find that it's just a matter of getting the filter mod pots in the right spot to respond to my playing/pickup selection.
Title: Maestro Filter Sample and Hold
Post by: niftydog on July 05, 2005, 10:31:08 PM
Quote
I have uploaded the mp3 Ry sent me. Here's the link:


Wow, cool! I wish MY alarm clock sounded that funky!  :P
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 08, 2005, 02:42:59 PM
Ry,

Did you use the MAX1044 with the GGG build too?

I am trying to find the source for the whining.

Since it doesn't change with the LFO speed it may be the MAX1044, maybe worth it to try it without it and power it with a bipolar supply, just to discard that possibility.

Fp
Title: Tonepad FSH-1
Post by: soggybag on July 08, 2005, 02:55:18 PM
I used a MAX1044 in my build. I did the first test with a 7660 then switched over to the 1044 after the first round.

Yes I notice that the whine does not appear to be effected by the speed of the LFO. I thought the 1044 was supposed to be above audio. There's something on the datasheet about connecting two pins to (or maybe it's put a cap across two pins) to make the charge pump work at the higher speed.
Title: Maestro Filter Sample and Hold
Post by: Bill Bergman on July 08, 2005, 02:58:34 PM
I have several pedals with 1044 power circuits in them using the extra cap. They didn't seem to whine.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 08, 2005, 03:07:59 PM
Bill,

I haven't had a chance to check the file you sent me, I will later today, and post the mods to the existing board. If that's the source of the whining the circuit would be verified, as that seems to be the only problem with it.

Thanks for the file!

Fp
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 08, 2005, 03:09:47 PM
Soggy,

Does your build sound the same as Ry's? Could you send me a sound sample?

Fp

(sorry for the two posts!)
Title: Maestro Filter Sample and Hold
Post by: Ry on July 08, 2005, 03:35:02 PM
Sorry FP, I missed the last question to me.  Yes, I built the GGG version with a 1044 as well.  I'm dubious that it is the problem.  I've built other pedals with it that didn't whine at all.

Here's what I'll do for you, though.  I will pull my 1044 from the circuit and wire up another 9v battery so that I can get -9v without using the charge pump.

Expect a report back.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 08, 2005, 03:37:03 PM
Ry,

That'll be of great help.

Fp
Title: Maestro Filter Sample and Hold
Post by: Ry on July 08, 2005, 04:03:43 PM
That was quick and easy, just pulled the chip and plugged the battery snap into the correct socket locations.  It didn't help any of the bleed-through, sorry to say.

What else can I try?
Title: Maestro Filter Sample and Hold
Post by: leonhendrix on July 08, 2005, 08:41:16 PM
Im about to start the nuetron filter from geofex and he says the layout is designed to prevent whine but if you are still getting whining you can insert two chokes instead of two jumpers (you'll have to look at the layout to see which ones he means). The parts list has the choke values at 680uH.

leon
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 08, 2005, 09:26:57 PM
Ry,

Thanks for trying that. I have compared Bill Bergman's file for the MAX1044 and it's the same (without the transistor to switch the circuit off when there's no jack plugged in... which I will add to the next revision of the layout BTW).

What I find odd is that the whining's speed is not affected by the LFO's speed...

I'll study it a little more, in the meantime, any help from others is greatly appreciated.

Leon, I don't know about the neutron filter, I'll read about it as well.

Fp
Title: Maestro Filter Sample and Hold
Post by: leonhendrix on July 08, 2005, 09:57:18 PM
I thought id mention it cos RG modded the neutron to use a charge pump as you have done with the FSH

leon
Title: FSH-1
Post by: soggybag on July 17, 2005, 07:24:07 PM
I tried hooking two 9V batteries to the DC jack as the power supply and recorded a could of samples. This seemed get rid of most of the noise I was experiencing.

These samples are a little quiet.
sample and hold mode
http://webdevils.com/stompbox/audio/FSH-1_01.mp3
Filter mode
http://webdevils.com/stompbox/audio/FSH-1_02.mp3

There is some bleed thorugh of the LFO on the sample. it's hard to hear in this sample.

I am still having trouble getting the Up/Down sweep switch working. It works in one direction but I get no audio in the other setting.
Title: FSH-1 Audio Samples
Post by: soggybag on July 18, 2005, 12:11:45 PM
I updated the sample and hold track to better hear the background noise. You definitely here the LFO back there. It's not too bad. On some setting it is not as noticable.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 18, 2005, 12:26:10 PM
Soggy,

That sounds pretty good. I can hear the click on the new updated sample. It is possible that a 0.1 or so capacitor added right on the ic's pins 8 and 4 and replacing the jumper to the left of IC3 with a 10 ohm resistor could decouple the power supply if that's the source of the click.

The other place that could be source of problem is the traces to the resonance pot, I wanted to have the pot on the edge of the board and that's why those long traces are there but they could be picking up the lfo click. That's a bit harder to fix, you'd have to cut the traces and drill new pads.

I haven't had a chance to build my own. I wonder why the 1044 is giving so much problems, could it be the current draw surge that LFOs seem to have?

Fp
Title: Maestro Filter Sample and Hold
Post by: Ry on July 18, 2005, 09:09:23 PM
Soggy,

Does your circuit sound different with the 1044?  It didn't make a difference when I used two batteries.

Yours sounds so much better than mine.  I need to try to reduce the bleedthrough somehow.
Title: FSH-1 Audio Samples
Post by: soggybag on July 18, 2005, 09:39:31 PM
I used two batteries but attached them with aligator clips. I attached them at the DC jack and everything seemed to work. I also tried attaching them to one of the big caps at the PS. It seemed to work there also. Though it did drain the batteries very quickly.



I have been testing with the wallwart, but I did the recording with the batteries.

I'm having problems with the up/down switch.

Right after I tested this morning it stopped working again!

I swear, I moved one wire on the up down switch, only one single wire, and I don't know what happened now when I plug in the wallwart the 1044 gets really hot? This had me so infuriated this morning!

I even put the wire back and it still didn't work again? I think I will have to do some trouble shooting...
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 19, 2005, 12:12:30 AM
Ry, Soggy,

I have updated the pdf to show the two DPDT switches. Check it out.

Fp
Title: FSH-1 Audio Samples
Post by: soggybag on July 19, 2005, 11:31:51 AM
Thanks for posting the updated diagram. It looks like Ihave everything wired exactly the same. It seems the down sweep is not working and the up sweep is working. I'm checking all of the component values in the imediate area...
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on July 19, 2005, 12:08:24 PM
I wish Tonda could post some info on his mods (that I have included in the pdf). I believe he compensates the circuit changes with all those resistors in order to just flick the switch and change the sweep direction, rather than also have to adjust the sensitivity (as it is with the MXR Envelope Filter). Which makes the switching a bit more complex.

Still, I think the mp3s sound very promising, I have to find the time to build this one!

And sort out the MAX1044 issues....

Fp
Title: Maestro Filter Sample and Hold
Post by: Ry on July 19, 2005, 09:23:27 PM
My direction switch seems to work fine, but I haven't played with it too much.  The filter on this is really kind of a bonus feature, I'm most interested in the sample and hold.

I'm about to start the process of replacing my wire leads to the switches/pots with coax to see if that helps the bleedthrough issues I'm having.

I had to put this thing down for a couple weeks because it gave me a headache to think about, but I'm back at it.

Ry
Title: Maestro Filter Sample and Hold
Post by: soggybag on August 26, 2005, 11:37:11 PM
I made the LFO and sample and hold sections on a breadboard and have been getting a lot of bleed through of the LFO into the noise signal. I think the LFO and might need to be on a singal opamp to isolate it.

II used a 1458 as the opamp. With the audio probe I can hear the LFO on the out of the noise amplifier. I should only be gettting noise.

The original might have used singal op amps for that reason.
Title: Maestro Filter Sample and Hold
Post by: Fp-www.Tonepad.com on August 27, 2005, 11:46:44 AM
Interesting. I'll think of a way to try using a single opamp.

Since you breadboarded it and it sounds the same, it's not likely to be a layout issue, but a circuit issue.

More later.

Fp
Title: Maestro Filter Sample and Hold
Post by: soggybag on August 27, 2005, 03:30:54 PM
I just breadboarded the LFO, noise and the sample and hold sections. I used a single +9v supply and made Vref with two 100k resisters and a 47u cap. Everything worked. I got good white noise. The LFO cycles.

But the sample and hold section didn't seem to be working correctly. I tested the noise at the op-amp output and there I see big spike with each cycle of the LFO.

I'm guessing that the LFO draws a large amount of current when it swings from one rail to the other.

I was able to smooth things out a little by adding some big filter caps. I think I change the 47u to 100u and added 1000u across the power supply.

Here's a drawing of what I built.

(http://www.webdevils.com/stompbox/images/SandH_01.jpg)