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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

August 29, 2012, 08:11:19 PM
Looking for information about this pedal. I have the schematic. I have a layout. I have even built a working pedal. So.... To my question.

The BBD called for in the schematic is a Reticon RD5106A. I have some R5106 (notice the subtle difference) that I used in the build but there is one big problem.

THEY ARE TERRIBLY NOISY!!  :o

So my question is....

Does anyone have this pedal or pics of this pedal that can tell me the EXACT part number that was used for the BBD?

I am rationalizing that the small difference in part numbers makes all the difference in the audio quality.

Any help would be appreciated  ;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.'

Govmnt_Lacky

#1
August 30, 2012, 02:57:01 PM
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.'

oldschoolanalog

#2
August 30, 2012, 03:18:44 PM
In my personal experiences all the R510X BBD's are notoriously noisy/hissy. This is a chip that begs for companding or some form of noise reduction in it's chosen circuit.
Just my 2 tin cents...
Mystery lounge. No tables, chairs or waiters here. In fact, we're all quite alone.

Govmnt_Lacky

#3
August 30, 2012, 03:23:52 PM
Quote from: oldschoolanalog on August 30, 2012, 03:18:44 PM
In my personal experiences all the R510X BBD's are notoriously noisy/hissy. This is a chip that begs for companding or some form of noise reduction in it's chosen circuit.
Just my 2 tin cents...


Thanks Dave...

In my research, I have found the same thing. I just cant see how EHX would have used it in this circuit for so long with the noise issues though. There is no companding in the DEM V4 which is what leads me to believe that the RD5106A is a better chip for audio quality. I would just like to get some reassurance on that idea.
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.'

oldschoolanalog

#4
August 30, 2012, 03:34:58 PM
I'm not really sure if the "A" suffix really has much to do with fidelity. Compare SAD1024 to SAD1024A. I have found them to both sound the same. Maybe it's in the layout and use of ground planes in the EM design? I am just throwing some thoughts out there as I really can't say for sure. Maybe Puretube or Theehman can shed some light on this as they both have a vast knowledge of EH products.
Ton? Ron?
Mystery lounge. No tables, chairs or waiters here. In fact, we're all quite alone.

Jazznoise

#5
August 31, 2012, 06:23:57 AM
A few thoughts:

You could parallel a pair of BBD's, this will decorelate the noise for a theoretical impovement of 6dB.

Filter the DC input for the BBD further to prevent power supply ripple generating noise (if you've been using a battery and found the noise unchanged, ignore it).

Make the signal much hotter on input to keep above the noise floor. This may require larger power rails!

Decrease the circuit impedance to reduce johnson noise (again, at input this would be a far bigger factor). TL074's can drive a 2K load, not sure if you'd want to go lower.

Filter above 10Khz on the wet signal(bit of a bodge, but it'll help!)

Use a less noisey BBD! The MN series are supposed to be the cat's pyjamas!
Expressway To Yr Null

Govmnt_Lacky

#6
August 31, 2012, 07:38:49 AM
Quote from: Jazznoise on August 31, 2012, 06:23:57 AM
A few thoughts:

You could parallel a pair of BBD's, this will decorelate the noise for a theoretical impovement of 6dB.

Filter the DC input for the BBD further to prevent power supply ripple generating noise (if you've been using a battery and found the noise unchanged, ignore it).

Make the signal much hotter on input to keep above the noise floor. This may require larger power rails!

Decrease the circuit impedance to reduce johnson noise (again, at input this would be a far bigger factor). TL074's can drive a 2K load, not sure if you'd want to go lower.

Filter above 10Khz on the wet signal(bit of a bodge, but it'll help!)

Use a less noisey BBD! The MN series are supposed to be the cat's pyjamas!

I have tried filtering the DC input AND I have tried powering it from a steady source (the circuit I built runs on a charge pump but I also tested with a regulated PS) and nothing gets rid of the noise. The layout I did is basically the same configuration as the original unit except that I minimized the unused open space, added an on-board charge pump circuit, and shrunk it good enough to fit into a BB size enclosure.

I still believe it has something to do with the BBD part numbering. I highly doubt that EHX would have put out a pedal with THIS MUCH noise  :icon_eek: It flanges fine and the controls respond great. It simply is unusable because of the noise.

Still hoping that someone with a working pedal will see this and be able to tell me the exact part number from their BBD.  :-\
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

#7
August 31, 2012, 09:17:47 AM
Hmm, is the charge pump close to the BBD? I'm wondering your noise is just switching noise now...but the PS idea contradicts that! Can you or have you tried to bypass the charge-pump with a power supply and test the results?

Is the noise spectral or is it "white"? A clip or even an FFT shot would greatly help me understand what kind of noise you are experiencing!
Expressway To Yr Null

Govmnt_Lacky

#8
August 31, 2012, 09:25:01 AM
Quote from: Jazznoise on August 31, 2012, 09:17:47 AM
Hmm, is the charge pump close to the BBD? I'm wondering your noise is just switching noise now...but the PS idea contradicts that! Can you or have you tried to bypass the charge-pump with a power supply and test the results?

Is the noise spectral or is it "white"? A clip or even an FFT shot would greatly help me understand what kind of noise you are experiencing!

I am using an LT1054 chip in the charge pump so it can handle the higher mA draw of the circuit. The only down side of that is that it DOES NOT have the same frequency doubling/boost capability of the MAX1044 and other chips  :-\

I am going to try to remove the 12V regulator from the circuit and just directly inject the 12VDC from my regulated PS into the circuit and see what happens again. I am 90% sure I already did this and it was still noisy but I will try again.

I cannot do any video/audio clips as I do not have the tools to do so however, if I could explain the noise it is much on par with AM radio/Tune in Tokyo type noise. Almost like you are rolling the dial on a manual tune radio back and forth. This changes with the Rate knob as well.
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

#9
August 31, 2012, 10:38:01 AM
Poop, that tells me nothing other than the noise undergoes comb filtering/gets flanged. My bad! Set it to filter matrix and take a tap from the output of the BBD and turn the color knob to 0. White noise? Ticking?

I'm hoping this is PSU noise or a ground issue  :icon_confused:
Expressway To Yr Null

Govmnt_Lacky

#10
August 31, 2012, 10:51:27 AM
Quote from: Jazznoise on August 31, 2012, 10:38:01 AM
Poop, that tells me nothing other than the noise undergoes comb filtering/gets flanged. My bad! Set it to filter matrix and take a tap from the output of the BBD and turn the color knob to 0. White noise? Ticking?

I'm hoping this is PSU noise or a ground issue  :icon_confused:

Thanks. Will try that later this evening 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.'

blueduck577

#11
August 31, 2012, 02:02:29 PM
Quote from: Govmnt_Lacky on August 31, 2012, 09:25:01 AM
I cannot do any video/audio clips as I do not have the tools to do so however, if I could explain the noise it is much on par with AM radio/Tune in Tokyo type noise. Almost like you are rolling the dial on a manual tune radio back and forth. This changes with the Rate knob as well.

I had a similar problem with my DEM from EHX with the RD5106A chip and made a video.  Is your problem anything like this:


I made a thread here a while ago about it: http://www.diystompboxes.com/smfforum/index.php?topic=87204.msg732560#msg732560. I haven't figured out what the problem was, it seems to have gone away by itself.  It only would happen with my telecaster that had active pickups and not with my strat with passives.  No charge pump in this circuit, it's being powered by the provided EHX wall wart.

Govmnt_Lacky

#12
August 31, 2012, 02:14:45 PM Last Edit: August 31, 2012, 02:20:17 PM by Govmnt_Lacky
@blueduck

THAT'S IT!!!

From about the 12 second mark of the video is exactly how my pedal sounds. It still flanges but it has that constant AM radio noise.

I also run active pickups (18V  :icon_twisted:) but sadly I do not have a passive guitar.

For those interested... The video is exactly what I am hearing. Any advice to get rid of the noise with active pickups?

EDIT: actually if I remember correctly, it makes the noise without my guitar plugged in. More to follow after work!
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

#13
August 31, 2012, 03:43:56 PM
Try with a capacitor, 10nF or more, from BBD pin 6 to GND.
If it's a clock-reaching-input issue, then it might be dimmed or better...
If noise comes from BBD's guts, you now know what's the purpose of double outputs in other BBDs...  :icon_cry:
"NOT FLAMMABLE" is not a challenge

Govmnt_Lacky

#14
August 31, 2012, 04:14:11 PM
Quote from: Fender3D on August 31, 2012, 03:43:56 PM
Try with a capacitor, 10nF or more, from BBD pin 6 to GND.
If it's a clock-reaching-input issue, then it might be dimmed or better...
If noise comes from BBD's guts, you now know what's the purpose of double outputs in other BBDs...  :icon_cry:

Thanks for the tips Fender.

I don't have any caps with me to try tonight but I can give it a go tomorrow.

Tonight I am going to try bypassing the charge pump with a regulated 12V supply and also try to audio probe the BBD output like instructed above.

More to follow later  :icon_wink:
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

#15
August 31, 2012, 04:21:17 PM
It sounds like it's oscillating. Blueduck I beleive 12bass in the previous thread got it right and it's due to some very high frequencies in the feedback loop! Try increasing the 47nF (C13 in the other thread) capacitor in parallel with the colour knob to 100nF and see what happens.
Expressway To Yr Null

12Bass

#16
August 31, 2012, 05:29:17 PM
Quote from: Jazznoise on August 31, 2012, 04:21:17 PM
It sounds like it's oscillating. Blueduck I beleive 12bass in the previous thread got it right and it's due to some very high frequencies in the feedback loop! Try increasing the 47nF (C13 in the other thread) capacitor in parallel with the colour knob to 100nF and see what happens.

The ring-modulator-esque sound in the video sounds like aliasing noise.  It is caused when frequencies which are greater than 1/2 the sampling rate get into the BBD path.  What is produced is a bunch of sum and difference frequencies.  If the charge pump runs at anything close to the clock frequency, it may be injecting high frequency noise into the delay path, causing the aliasing noise.  Moving the charge pump farther away may help.  As suggested above, a steeper low pass filter may also help.  I've experienced the same thing with my SAD1024A A/DA clone, but with much less severity.  Basically, I can only hear aliasing with test tones, not with recorded music or an instrument.  BTW, if it is aliasing, the noise should go away with very short delay times (high in the sweep), because the BBD sampling rate will be too high for 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

#17
August 31, 2012, 05:36:19 PM
Quote from: 12Bass on August 31, 2012, 05:29:17 PM

The ring-modulator-esque sound in the video sounds like aliasing noise.  It is caused when frequencies which are greater than 1/2 the sampling rate get into the BBD path.  What is produced is a bunch of sum and difference frequencies.  If the charge pump runs at anything close to the clock frequency, it may be injecting high frequency noise into the delay path, causing the aliasing noise.  Moving the charge pump farther away may help.  As suggested above, a steeper low pass filter may also help.  I've experienced the same thing with my SAD1024A A/DA clone, but with much less severity.  Basically, I can only hear aliasing with test tones, not with recorded music or an instrument.  BTW, if it is aliasing, the noise should go away with very short delay times (high in the sweep), because the BBD sampling rate will be too high for aliasing to occur.


It's actually a mirror frequency, but yes! (Going 100hz over SR/2 produes a tone of SR/2-100). Going VERY far over the nyquist produces very low frequencies until you hit the lower nyquist and they begin to reflect back upwards. Interesting and fun stuff, but obviously nobodies goal here!

From the video the more I listen the more I think it's aliasing. Hearthe way at the start it's at the end of the LFO cycle at, presumably, the longest delay time on that setting? Resetting the input capacitor might help, but I'vea feeling it's when he messes with the colour knob that the intensitie varies the most so my moneys there...until it doesn't work, of course!  :icon_twisted:
Expressway To Yr Null

Mark Hammer

#18
August 31, 2012, 05:40:04 PM
Two clocks in the same box is a recipe for trouble, especially if they are not that far apart in frequency.

This is why many digital pedals can sound dead quiet when powered by their own unique power supply, and noisy as hell when two or more are sharing the same wall-wart without any power filtering between the two pedals.

Skip the charge pump and just power the thing with an appropriate supply.

ORK

#19
September 01, 2012, 02:20:50 AM
And when powering with a regular PS, be sure to UNpower the chargepump IC. It makes me wonder btw, that there is not a single small cap (100nF) to be seen anywhere across the power rails in any of those mistress schematics. Did EHX use those IC-sockets with built-in ceramics by chance, which might got lost in the tracing process?
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