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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

#40
November 15, 2012, 08:44:01 AM
OK...

As I am really frustrated that this is on the shelf, I decided to look at it one more time.  :icon_rolleyes:

Something that I did notice in my design is that the V- rail appears to form a big loop around the outer egde of the PCB. In other words, it looks like a big complete ring around the outer edge of the board with the needed V- points tapping off at certain spots of the "ring."

Could this cause possible noise issues? Does this ground "ring" need to be broken at some point?

The best example I could give is that it looks like the following Tonepad layout except that MY outer V- rail is not broken like it is on the right side of this Tonepad layout

http://www.tonepad.com/getFile.asp?id=122

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.'

Fender3D

#41
November 15, 2012, 10:50:40 AM
You'd always better avoid rings...
Either on PCB or when "requested" by women...  :icon_mrgreen:
"NOT FLAMMABLE" is not a challenge

Govmnt_Lacky

#42
November 15, 2012, 11:14:39 AM
Quote from: Fender3D on November 15, 2012, 10:50:40 AM
You'd always better avoid rings...
Either on PCB or when "requested" by women...  :icon_mrgreen:

Got it!  ;)

After posting this... I went back and looked at pics of a factory DEM V4 (earlier in this thread) and it looks like EHX ran their ground in a big loop around the PCB 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

#43
November 15, 2012, 03:03:22 PM
Did you try the capacitor thing?

Haven't gotten to look at the PCB, I reckon the schematic may have issues - what I heard in that YT video still sounds like Aliasing to me.
Expressway To Yr Null

Govmnt_Lacky

#44
November 15, 2012, 03:12:19 PM
Quote from: Jazznoise on November 15, 2012, 03:03:22 PM
Did you try the capacitor thing?

Haven't gotten to look at the PCB, I reckon the schematic may have issues - what I heard in that YT video still sounds like Aliasing to me.

Havent gotten to try the cap. Probably wont get time to until the weekend or maybe even next week  :icon_redface:

Ill post what I find with it though  ;)
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

#45
November 15, 2012, 08:51:19 PM
Quote from: Jazznoise on November 15, 2012, 03:03:22 PM... what I heard in that YT video still sounds like Aliasing to me.

I tend to agree.  Going to try to get my flanger back soon and record some clear examples of aliasing noise.
It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring. - Carl Sagan

12Bass

#46
November 18, 2012, 11:41:55 AM
Here's a sample of deliberately produced aliasing noise from my A/DA flanger clone.  It is the result of the BBD clock of the flanger aliasing with a 20 kHz square wave sent from a frequency generator.  For this sample, I set the flanger at the very bottom of its range, which should have a BBD clock of around 34 kHz.  If what you're hearing sounds like this, then the BBD clock is aliasing with another signal.

http://members.shaw.ca/kevinmacza/20_kHz_aliasing_sample.wav
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

#47
November 18, 2012, 07:47:23 PM
@12Bass

That is "some" of the noise that I am hearing. Just not that pronounced. It has been a while since I have ran up the circuit. I need to get a sound sample recorded and uploaded/linked here.

Any recommendations for services?  ;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.'

12Bass

#48
November 19, 2012, 02:51:10 PM
YouTube is an option, or SoundCloud.  My ISP offers free webspace, which is what I use.

BTW, I think the frequencies in my aliasing sample are incorrect due to a mix up when recording.  The frequency generator was set to output at a 96 kHz sampling rate, but the recorder was set to record at 44.1 kHz; so I think the square wave sent to the flanger may have been around 8.4 kHz, not 20 kHz.  Also, the noise is really loud because it was deliberately produced and normalized to maximize the volume.  In practice, with normal music signals, the aliasing noise is not audible.  I just wanted to provide a clear example of what aliasing sounds like for reference.

My guess is that the BBD clock signal may be leaking into your audio path, or perhaps there is a problem with the LPF in the audio path, or both.
It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring. - Carl Sagan

Jazznoise

#49
November 19, 2012, 03:31:44 PM
Good god that aliasing is horrible, well done!  :icon_lol:

I agree, 12 Bass, I think the input filter is wrong - my suggested mod to the cap on the input of the LPF before the bucket brigade might help. I think the value listed has a cutoff far too high for the BBD. 2n or even 4n of input capacitance should get you closer to a trouble free life (At least with flangers, anyway).

I haven't forgotten the layout you sent me, but I'm currently feeling like a bag of warm poo due to a cold so you'll have to be patient!
Expressway To Yr Null

Govmnt_Lacky

#50
November 19, 2012, 03:37:22 PM
Quote from: Jazznoise on November 19, 2012, 03:31:44 PM
Good god that aliasing is horrible, well done!  :icon_lol:

I agree, 12 Bass, I think the input filter is wrong - my suggested mod to the cap on the input of the LPF before the bucket brigade might help. I think the value listed has a cutoff far too high for the BBD. 2n or even 4n of input capacitance should get you closer to a trouble free life (At least with flangers, anyway).

I haven't forgotten the layout you sent me, but I'm currently feeling like a bag of warm poo due to a cold so you'll have to be patient!

What do you think the range could go UP to? I was looking over the pics of an EHX board and, I know this isn't an exact science but, it appears that the cap you are referring to is about the same look, shape, and size of some other 100nF caps on the board.

I am wondering if this is REALLY another screw up on the schematic and the actual units used a much bigger cap in that spot.  :-\
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

#51
November 19, 2012, 03:48:22 PM
I think anything 2n would cut anything above 20khz, 4n 10khz and 8 in 5khz. 8 would probably be the upper limit before your flanging began to lose it's sparkle.

Of course that's me looking at the filter in isolation, I'm not sure how the loading from the previous stage will effect it - that's more of a PRR thing!  :P
Expressway To Yr Null

Govmnt_Lacky

#52
November 19, 2012, 09:08:29 PM
OK...

Ran parallel caps with the 1nF in the filtering section. From 1nF to 100nF  :icon_eek:

Some of the noise dissipated however, other parts of the noise were CLEARLY unaffected  :'(

Cut the loop trace in the grounding AND verified ALL component values, placement, and orientation. All is correct. STILL GOT NOISE  :icon_evil:

I think I may need to get some cheezy audio sample posted so you can hear my pain.

Any recommendations for a good place to upload audio samples?
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

#53
November 19, 2012, 09:47:59 PM
Quote from: Jazznoise on November 19, 2012, 03:31:44 PM
Good god that aliasing is horrible, well done!  :icon_lol:

Perhaps this dates me... but I think that the aliasing noise sounds a lot like the sound effects in Galaxian.  Those who have ever played the game will understand.  :icon_wink:
It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring. - Carl Sagan

Jazznoise

#54
November 20, 2012, 06:02:31 AM
Dropbox is fine for hosting! Did you notice any treble loss on the "Wet" side as you went through those values? 100n should be muffled blanket!

This is perplexing. Honestly, I'm starting to think your BBD's delay times are just becoming too long to be useful in the audio range. That said, due to the pitch of the noise being around 2-3Khz I can't see the sampling frequency going below 5khz. The only other question is is there a large noise source onboard the pcb.

Those crazy inharmonic noises are always very sci-fi to me, 12bass!  :icon_lol: Ever listened to Melt Bannana?

http://www.youtube.com/watch?v=yOEILhkXv5c
Expressway To Yr Null

Govmnt_Lacky

#55
November 20, 2012, 07:21:51 AM Last Edit: November 20, 2012, 07:34:41 AM by Govmnt_Lacky
Quote from: Jazznoise on November 20, 2012, 06:02:31 AM
Did you notice any treble loss on the "Wet" side as you went through those values? 100n should be muffled blanket!

Absolutely! As I went up through the values, I noticed a treble cut with each increment. Like I mentioned above, SOME of the noise dissipated however, MOST of the noise remained.

Quote
This is perplexing. Honestly, I'm starting to think your BBD's delay times are just becoming too long to be useful in the audio range.

In this circuit, I am using an R5107 for the BBD instead of the R5106. I adjusted the clock trimmer to 25K in order to double the clock frequency as the 5107 is a 512 stage BBD and the required R5106 is only 256 stages. From the research I have done, this is what needs to be done in order to support the extra delay stages. (Double the delay = Double the clock frequency)

Am I wrong?

I will try to put something up from Dropbox as soon as possible. It may not be the best quality but, I will try to capture what I am hearing.

EDIT: @Jazznoise

Were you able to look at my PCB design? Did you see ANYTHING that looked wrong compared to the schematic?
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

#56
November 20, 2012, 09:24:44 AM
With a 512-sample device (RD5107A), the BBD clock should not drop below 34 kHz.  Even that would be really low for a flanger, producing a 15 ms delay.  1.024 MHz would provide a 0.5 ms delay, which would be reasonable for the maximum clock.  In short, the BBD clock should be high enough that aliasing with the frequencies normally generated by guitar signals should not be a major issue, unless there's a problem in the circuit.

Melt Banana sounds pretty crazy!    
It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring. - Carl Sagan

Jazznoise

#57
November 20, 2012, 09:39:53 AM
A highpass filter on the clock leg could help to keep it well outside of the audio band. I'm not sure how that would interfere, as its the rising edge that the clock input is really looking for, but if the -6dB point was 20Khz then problems should be minimised. I'm wondering is there crosstalk between the clock and input, but how can we reduce it?

Are you using the CD4013 to generate your word clock? I'm not au-fais with some of these things by any means but I've been told CMOS 555's generate less ticking than some other models. Is your D Type CMOS?

What program did you use to generate the .pcb? It's not opening in Ultiboard!
Expressway To Yr Null

oldschoolanalog

#58
November 20, 2012, 09:43:15 AM
Read this entire data sheet first. Do the math. The R5107 is the equivalent of a 1024 stage BBD. It has specific clocking requirements in regard to frequency and rise/fall times for the clock you are using. If these are out of spec maybe this is contributing to noise issues. Maybe.
Just an observation.
http://thmq.mysteria.cz/em1022/RD5107.pdf
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12Bass

#59
November 20, 2012, 09:46:04 AM
Note: the data sheet for the RD5107A states that it is a 512-sample device, not a 512-stage device.  The SAD1024A is a dual 512-stage device, which can use the two BBD sections in series to produce a combined 1024-stage device.  Perhaps the difference is due to the fact that the RD510x series only uses a single clock (tick, tick, tick, tick), while the SAD1024A employs a two-phase clock (tick, tock, tick, tock).  The result is that each 512-stage section of the SAD1024A produces 256 samples - or one sample for each pair of complementary clock signals. 

In summation, the 512-sample RD5107A can be viewed as equivalent to a 1024-stage device, with the BBD clock set accordingly.  If my math is correct, the above frequencies should be in the ballpark.   
It is far better to grasp the universe as it really is than to persist in delusion, however satisfying and reassuring. - Carl Sagan
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