comparing analogman clone chorus to tonepad..

[dubs]

Had a look inside  a analogman clone chorus. One of the nicest quality pedals I've ever seen. He uses a ground plane on his circuit boards to minimise noise/ interference. I've NEVER seen this on a effects pedal before. I suppose most people can't be bothered.
All carbon comp resistors.

Anyway, he uses 1 M reverse log pot for speed  and 10k linear pot for depth. The center lug of the depth pot goes to a 39K resistor then 1n4148 diode which goes to pin2 of cd4047. Left lug to ground. Right lug to pin 1 of lm358N.
O.k So it looks the same as the tonepad schematic apart from the pot value (tonepad quotes 100k).

Maybe this is why some people say the depth on the tonepad layout is not as deep? I dunno..

[dubs]

Here are pics of analogman's work (ver3.0)- beuutiful work! This is one of the best built pedals I've seen. I guess he built his name making quality stuff:





If this is bad  i'll take it down.
Some things I noticed (from what I could see) compared to tonepad schem:
-No 47 ohm resisitor from +9v  but  1n4148 diode instead (reverse polarity protection for transistor?)
- 100 ohm electro (on right next to Lm358) & no 220 ohm electro in circuit
- use 100pf to pin1 of CD4047 as opposed to 150pf on tonepad

I'm curious to note what mods is done to remove volume drop and increase the depth of effect..
Thoughts anyone?

[bobbletrox]

All carbon comp resistors.

You don't mean carbon film, do you?

[Ed G.]

Analog Mike's site mentions a 'secret' component value that was found in the old pedals, but not in the schematics.
I believe the original cap in the schematic was .0027 but the 'magic cap' was .0039. I can't remember where the part was, it's the only components with those values in the whole circuit.
I built a small clone and used the .0039 and did not notice any volume drop whatever. I used a good polystyrene cap here. Sounds great!

[jimbob]

thanks for the pics! i always wondered what analog mikes effects looked like on the inside--very quality-i can see the reason for the pricing now.

[dubs]

I've look at the parts inside the pedal and he uses the 0.0027 cap not a 0.0039. Seems like he's tweaked a few other things in the circuit. Damn it's the nicest fattest chorus I heard and does an  awesome leslie thing!  I'll have to built one and muck around with the circuit myself.

[Ed G.]

Well, that answers that question...
I wholeheartedly endorse building the tonepad project. It sounds great, I'd like to compare it to analog mike's one.
Check out moosapotamus.com for the 'wavy gravy' it's a bunch of mods to the small clone. Only one I did was to make the status LED 'blink' with the speed of the chorus. Neat-o.
Seriously, Mike's got a great-looking pedal and I know there's been some debate about the prices of boo-teek pedals, but if I couldn't build my own, I'd definitely buy one of his.

[modmod]

Some things I noticed (from what I could see) compared to tonepad schem:
-No 47 ohm resisitor from +9v  but  1n4148 diode instead (reverse polarity protection for transistor?)
- 100 ohm electro (on right next to Lm358) & no 220 ohm electro in circuit
- use 100pf to pin1 of CD4047 as opposed to 150pf on tonepad

I'm curious to note what mods is done to remove volume drop and increase the depth of effect..
Thoughts anyone?

where was the original 220ohm ? can't find it in the schematic  :?

[mikeb]

thanks for the pics! i always wondered what analog mikes effects looked like on the inside--very quality-i can see the reason for the pricing now.

I had a discussion with Mike P when we were talking about him distributing the infinitphase - without giving away the pricing details he definitely *isn't* getting rich of dealing / selling pedals.

Mike

[puretube]

dunno the circuit (link?),
but maybe these:

100 ohm electro (on right next to Lm358) & no 220 ohm electro in circuit

are 100 / 220 microfarad (aka 100 / 220uF) electrolytic capacitors?

[george]

I'm curious to note what mods is done to remove volume drop and increase the depth of effect..
Thoughts anyone?

what volume drop??? I don't notice any on mine.

What do you mean increase the depth of the effect? Increase the sweep of the LFO or the intensity?

Oh yeah and the resistors just look like your regular 5% tolerance carbon film resistors that you can get from Jaycar or wherever ...

[dubs]

here's tonepads circuit:
http://www.tonepad.com/getFile.asp?id=8

I realised the 220uF electro cap in tonepads layout (but not  in the schematic) is a hum filter for the power supply. Yes AM 100Uf is electro cap.

As to  depth analogman claims to increase it by 25%. It sounds like to me he's increased the intensity. I think he's used 1uF  than 2.2uf going to lm358 as there's no 2.2uf in his board. also there's a couple less electrolytic caps in his circuit.

yes his resistors may look fairly "standard" but his circuitboards are groundplaned with rivets and those wouldn't be cheap to manufacture. Also he got custom made steel enclosures which look awesome and built tougher than most other pedals I've seen.

[Mark Hammer]

On effect "depth".  With both phasers and flangers, and to a lesser extent, chorusses, the "depth" of the effect - that is, how thick and obvious the effect seems to be at any speed - is partly a product of path-to-path matching of dry and wet signals.  If the overall amplitudes of the dry and wet signal are not well matched, the degree of cancellation is reduced.

Some manufacturers will include some sort of mix/blend control to allow the user to zero in on a signal combination that produces maximum cancellation, where others will leave things in the hands of two 5% resistors of selected nominal value, that ought to, in principle, produce a perfect 50/50 blend.  Of course, having a 5% tolerance does not necessarily mean that all parts of that value are always more than 4% away from their nominal value, but the possibility does arise that the dry and wet signals are not as well-matched as they might be.  

I see from the pictures that there is a trimpot near the 4558 that forms the input and output stages.  I'm guessing here, but I wonder if the greater perceived effect depth is a function of better dry/wet balance via the trimpot.  Alternatively, is the trimpot part of setting the gain of the mixing/output stage?  If so, perhaps that may have something to do with the reported absence of volume drop.

Just as an aside, those who have built a Heladito may want to consider swapping the 22k fixed resistor linking the output of the first op-amp to the second, for an 18k resistor and 10k trimpot, so that a perfect 50/50 balance can be obtained.  Alternatively, consider replacing the 20k mixing resistor from the delay section with a 15k fixed resistor and a 100k pot.  This will allow you to inject just a bit more wet than dry (and presumably nudging the pot back just a bit will nail a perfect 50/50 blend), but also allow you to roll back the wet side for subtler chorus effects.

What I'm wondering about is the additional unused traces on the board around the MN3007.  My first reaction is that the board was designed around using either an SAD-1024 OR an MN3007, whichever could be bought in cheap and large enough quantities.

[dubs]

I see from the pictures that there is a trimpot near the 4558 that forms the input and output stages.  I'm guessing here, but I wonder if the greater perceived effect depth is a function of better dry/wet balance via the trimpot.  Alternatively, is the trimpot part of setting the gain of the mixing/output stage?  If so, perhaps that may have something to do with the reported absence of volume drop.


What I'm wondering about is the additional unused traces on the board around the MN3007.  My first reaction is that the board was designed around using either an SAD-1024 OR an MN3007, whichever could be bought in cheap and large enough quantities.

Thanks mark for your comments. I think AM has really got the 50/50 wet dry blend happening as the effect is really thick and full.

The trimpot you mentioned is to adjust the bias voltage.

As for the unused traces yes you're probably correct, perhaps also to allow room for additional mods he does like a stereo jack and a "deep" mod??

[puretube]

dunno for sure bout the 3007, but the MN3207 is available in 2 different packages:
version "A" in 8-pin DIP,
and "B" in 14-pin DIP, where only the outer 2 pins on each side are used,
so you have the 3 inner pin-spots on the PCB  available for routing traces.

[Mark Hammer]

Ton,

Don't think it's for any alternate package of the MN3207, since: a) there are more pins (16) involved than any normal 14-pin Matsushita package, and b) more of the pins are connected to traces than what you describe.

Dubs,

I was guessing about that blue trimpot, on the basis of its distance from the BBD itself, but also because I thought that grey thing just to the right of the 4047 was a vertical mount trimpot.  Of course, had I looked at both pictures, I would have realized that the grey thing was not an electrical component at all but simply the standoff for supporting the board (note the holes where the "grey things" used to be when the board is flipped over).  As the only trimpot, obviously it has to be a bias trimpot.  There don't seem to be any 1% resistors on the board so conceivably, if there actually IS better wet/dry balance, it may stem from picking 5% components out of a bin and matching them according to some criteria.  In some instances, the higher quality sound that people hear from such pedals can come from selecting not only better quality parts,but from selecting parts that actually HAVE a given value rather than just those which INDICATE that value.

[puretube]

not so sure, Mark: lets call the pin 1&16 : they`re obviously grounded;
the other holes (where no actual pin of a "B" version would be soldered),
maybe just there for "vias".
Before I got my BBDs from Belling, I didn`t know what they were gonna send me, so I made a delay PCB layout for both versions, and it frighteningly looked similar (the 8-pin socket set-off 1 pin aside the 14 pin; mine was a single-sided, though).

But I`m not gonna argue with you  

[Mark Hammer]

I suppose it is a possibility that although the pads look like they ought to be for a 16-pin DIP, they may be for a 14-pin with two of the pads simply being for connecting board-top to board-bottom.  Hard to know from the picture.  At least part of my suggestion stemmed from the knowledge that E-H did produce a SAD1024-based Small Clone for a short while before turning to the 3007.

In any event, not that critical to me what thoe pads are for.  I just thought it was interesting that the board obviously could accommodate two versions of the same circuit.

The more important news is that my wife got a digital camera this week so I can finally get around to taking and posting lots of close-ups of the Guild Tri-Oct I am about to sell to someone I promised it to far too long ago.  The Tri-Oct is a hex octave divider/fuzz that uses a proprietary hex pickup.  The kicker is that the six individual octave circuits (mixed down to one for a mono output) are mostly 2N388's (Ge) and 2N5133's (an early E-H favourite, found in LPB'sand Muff Fuzz units).  I'm curious about how it works, but also curious about its lineage.  As you know, the relationship between Guild and E-H was an interesting one, with the Guild Foxey Lady eventually turning into the Big Muff.  Guild was also located nearby, from what I understand, so this may be one of those products that was Guild in name and E-H in spirit.  It's the only one I've ever seen.  Do a Google search for and the only thing you'll find about it is a review I submitted to H-C 3 years ago.

[puretube]

a digi-cam is such a fine thing! didn`t have one until a couple of weeks ago...

In the "Elektor"-magazine years ago, there was a nice article about a Hex-doubler,
which should yield a very clean "up", since the audioband was divided in six frequencybands, each individually fullwaverectified, then summed.

I know, that`s something completely different from a Hex-Pickup thing,
but maybe a nice idea for the modders....

b.t.w.: there`s still an old guitar in my garage or basement  somewhere, with a built-in self-wound hex-PU from 25 years ago...

[Mike Nichting]

Hell, I never could get mine to work~!! Dont have a clue why it wouldn't.
I used an NTE IC in place of the 3007 or ?? it is so that could be it but I thought the pinouts were the same??!!
If anyone is up for debugging it let me know. I've lost interest in it but I love the tone of theses choruses. Right now it is gathering dust waiting to be brought to life. I just can't do it.

Peace,
Mike