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Deluxe Electric Mistress V4 or V5

Started by Govmnt_Lacky, August 29, 2012, 08:11:19 PM

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Govmnt_Lacky

#20
September 01, 2012, 09:41:54 AM
Sorry guys. Didn't get a chance to try and debug last night. Will be able to try out everyone's suggestions either later tonight or tomorrow morning. More to come.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#21
September 01, 2012, 02:16:14 PM
OK fellas... here is the report and it is not good so far  :'(

Setup: Color at minimum. Range set variable during testing. Speed set to minimum. Mode set to Matrix. NO guitar/signal input. Input left open and output connected to amp.

- Bypassed the charge pump circuit and directly input 12V regulated to circuit. Still have noise. The noise changes with the Range and Speed pots. Still like the video.

- Inserted 100nF cap from V+ input to ground. No change!

- Inserted 10nF cap between BBD pins 6 and 2. No change!

If someone has the time and Express PCB, I would be willing to send them my layout to examine for possible problems. Otherwise, I am at a dead end.

Ideas?

Thanks  ;)

A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

12Bass

#22
September 02, 2012, 08:55:58 AM
Did you remove power to the charge pump, to ensure that it is not still generating noise?
It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring. - Carl Sagan

Govmnt_Lacky

#23
September 02, 2012, 11:07:04 AM
Quote from: 12Bass on September 02, 2012, 08:55:58 AM
Did you remove power to the charge pump, to ensure that it is not still generating noise?

Basically, I removed the 12V regulator from the circuit (socketed) and injected the 12V from the PS at the regulator output. So yes, I did not even have power on the charge pump circuit as the charge pump circuit was removed from the equation when I removed the regulator.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

12Bass

#24
September 02, 2012, 11:24:49 AM
OK, the charge pump IC has been removed, so it cannot be the source of the noise that is still present.  I'm going to see if I can make some recordings of aliasing with my A/DA clone for comparison.  From what I recall, the DEM design has fairly minimal low pass filtering on the delay path, so that might be contributing.  Still, I've minimized the filtering on my A/DA and it is not particularly noisy, nor does it produce much audible aliasing (unless it is deliberately fed a high frequency signal which produces aliasing).  Are you using any other pedals before the flanger?  I'm wondering if there might be some high frequencies (>10 kHz) being produced by something upstream which are causing the aliasing to occur?
It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring. - Carl Sagan

Jazznoise

#25
September 02, 2012, 11:47:49 AM
Did you try swapping the 47nf feedback cap for a 100nf?

I think, with the idea in mind that the noise is aliasing, that that's probably the money shot!
Expressway To Yr Null

Govmnt_Lacky

#26
September 02, 2012, 12:15:56 PM
@12Bass

I will be anxiously awaiting your findings.

@Jazz

I will try swapping the cap this afternoon. I see that cap is in parallel with the Color pot. The color pot does not seem to effect the circuit negatively. The problems seemed amplified more with the Range pot. When I turned the color pot I only noticed the flange effect and the overall noise floor was amplified.

Could this perhaps be a problem with running the LFO through a quad op amp? I seem to remember talks about circuit issues with this configuration. Possible solutions were to separate the LFO to its own dual op amp.

Will report on the cap swap later this afternoon.

Thanks to all who Have helped thus far  ;)
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Fender3D

#27
September 02, 2012, 01:26:31 PM
Greg,

if you have it on breadboard yet, you may try with different power supply for each circuit block (at least for clock section and BBD).
If the noise occurs with color CCW, I wouldn't mess with that block...
Although, to my ears, it seems being generating inside the chip...
"NOT FLAMMABLE" is not a challenge

Govmnt_Lacky

#28
September 02, 2012, 02:10:14 PM
Quote from: Fender3D on September 02, 2012, 01:26:31 PM
Although, to my ears, it seems being generating inside the chip...

This is what I fear as well. The only thing that makes me think otherwise is the fact that ALL of the chips sound identically noisy. That includes (2) 5106 chips with the clock set to 25uS and (12) R5107 chips with the clock set to 50uS.

I just dont want to face the fact that I might have 14 bad chips  :'(

Will try the 47nF cap swap in a bit and post results.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#29
September 02, 2012, 04:21:25 PM
Swapped the cap in parallel with the Color pot from 47nF to 100nF and to 220nF : Still noisy  :'(

This may be the first shelved project I have had in a LONG time!!  :icon_eek:

Only other options I can think of is either a whole lot of bad BBDs -OR- problems with the LM324 running the LFO instead of 2 dual op amps.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Fender3D

#30
September 02, 2012, 04:43:18 PM
Can you picture the clock waveform when the noise occurs?
Since you get it for a small delay frame, it may be BBD loading clock generator strangely...
"NOT FLAMMABLE" is not a challenge

Govmnt_Lacky

#31
September 02, 2012, 05:01:21 PM
Quote from: Fender3D on September 02, 2012, 04:43:18 PM
Can you picture the clock waveform when the noise occurs?
Since you get it for a small delay frame, it may be BBD loading clock generator strangely...

I cant do that at the moment as my oscope is currently at the office  :'(

I will try to do it sometime next week.

I am really confused about this as EHX put this circuit out as is. My layout is almost an exact replica of theirs except for eliminating the vast unused space and the inclusion of the charge pump circuit (which was already bypassed)
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

12Bass

#32
September 02, 2012, 10:06:16 PM
Before I can record clips, I'll have to retrieve my flanger from a friend.  Also, it uses the SAD1024A in a different circuit, so I'm not sure if the comparison will be that useful.  But it may help to illustrate what aliasing noise sounds like.
It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring. - Carl Sagan

Govmnt_Lacky

#33
September 24, 2012, 01:49:05 PM
OK folks... back to this again AND I think I found something promising in the quest to keep this OFF of the shelved list!  ::)

Take a look at this link. Particularly the schematic at the bottom AND the component-side board pics:

http://www.metzgerralf.de/elekt/stomp/mistress/deluxe-electric-mistress-v4.shtml

Pay close attention to C11 (220uF electro). If you notice, on the schematic it shows the + side of the electro at the junction of C9 and the 100K trimmer. On the actual board itself, it shows the + side of C11 at the junction of the 680R resistor and the 5K trimmer  ???

Could this be another FUBAR on the part of EHX?

Could this be what is causing all of the "Tune in Tokyo" noise that I am getting?

Thoughts??
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#34
September 24, 2012, 09:23:44 PM
In case anyone is interested...

Swapped around the 220uF cap and VIOLA!!!!

NO CHANGE!!!!  :icon_evil:  :icon_evil:  :icon_evil:

Still noisy as HELL!!!

Back to the shelf I guess  :'(
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Govmnt_Lacky

#35
November 13, 2012, 09:34:49 AM
I'm still willing to email the Express PCB layout to ANYONE who can look it over and see if I am missing anything  :'(

As this is my ONLY shelved project, I would love to get this up and running... or at least find out if my R5106 chip is indded the culprit.
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Jazznoise

#36
November 13, 2012, 12:15:16 PM
Hmm, my only final suggestion would be lowpassing the input. Try changing the 1n cap between pins 6 and 7 of IC1b for a 2nF should still keep you above the 20Khz mark. If it improves but is still a problem, bring it up to 4nF. After that you're really gonna start ruining your bandwidth (If we consider losing some of the top octave not ruination).
Expressway To Yr Null

Govmnt_Lacky

#37
November 13, 2012, 12:28:39 PM
Quote from: Jazznoise on November 13, 2012, 12:15:16 PM
Hmm, my only final suggestion would be lowpassing the input. Try changing the 1n cap between pins 6 and 7 of IC1b for a 2nF should still keep you above the 20Khz mark. If it improves but is still a problem, bring it up to 4nF. After that you're really gonna start ruining your bandwidth (If we consider losing some of the top octave not ruination).

Thanks Chris.

I have already found 1 error on the EHX factory schematic (the 220uF electro cap between the Bias and Mix trimmers is backwards compared to pics of an actual unit)... who is to say they didn't goof up a cap value?

Would you be willing to look at my Express PCB layout to verify?

Cheers  ;D
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'

Jazznoise

#38
November 13, 2012, 02:04:53 PM
I haven't built it, so I can't verify if the Schematic is correct. If you're unsure as to wether it correlates to the schematic, send it on and I'll look. If you are sure, I won't be of much help. Email it on and if I get a chance this week I'll check for errors, for now leisurely brainstorming will have to do you.

Unless I'm crazier than I thought, from reading the Datasheet I see the Max bandwidth for a 30mS delay is 8.6Khz. I just simulated the input circuit and my results are odd - nowhere near unity gain. Using a TL074 for now. Changing the cap to 2n does make a difference, however, and brings 20khz down about -3dB. Can't hurt. Get another 1n cap, touch its legs off the other 1n cap and see if the noise goes down, I say!

Expressway To Yr Null

Govmnt_Lacky

#39
November 14, 2012, 11:31:56 AM
@Jazz

I will send the Express PCB layout to you as soon as possbile. Thanks for the help offer  ;D

Anyone else want to step up and give this layout a look over? Don't be affraid... it wont bite!  :icon_mrgreen:
A Veteran is someone who, at one point in his or her life, wrote a blank check made payable to The United States of America
for an amount of 'up to and including my life.'
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