Madbean Total Recall 2024 - Can't calibrate

[Lorok]

Hey there

The problem​

Having been thoroughly enjoying Dan's DM-3 project, I've decided to try to tackle the legendary DMM in the form of MadBean's Total Recall. But even though I can get all the knobs to work as intended (there is delay with a mix from none to full wet, the repeats go from 1 to oscillation, the modulation warbles along), it just so noisy after hours of trying to calibrate.

I have tried both the scope (I have a cheap mini from Aliexpress) and audio probe methods to no avail: there is always noise along the signal path that I can't trim out.

Schematic​

Page 18 of @bean's pdf.

Voltages​

Here are the voltages with reference values from Madbean's build doc linked above in brackets. I notice that starting from the V571D, I have some oscillation that is being picked up by my multimeter in the VDC setting (I note it like "min ... max"), which the reference doc doesn't show:

Knobs @ 0

IC1 TL072CP
1 -7.58 (-7.66)
2 -7.58 (-7.66)
3 -7.55 (-7.62)
4 -15.02 (-15.12)
5 -7.5 (-7.57)
6 -7.57 (-7.61)
7 -7.57 (-7.66)
8 0 (0)

IC2 V571D
1 -13.83 (-13.88)
2 -13.10 … -13.21 (-13.27)
3 -13.10 … -13.21 (-13.27)
4 -15.02 (-15.12)
5 -13.18 (-13.28)
6 -13.15 (-13.26)
7 -5.77 .. -6.02 (-4.87)
8 -13.18 (-13.28)
9 -13.18 (-13.28)
10 -6.58 (-7)
11 -8.22 (-8.72)
12 -13.18 (-13.28)
13 0 (0)
14 -13.17 (-13.27)
15 -13.16 (-13.27)
16 -13.96 (-14.18)

IC3 JRC4558D
1 -7.86 .. -8.21 (-6.65)
2 -3.93 .. -4.11 (-3.32)
3 -3.93 .. -4.11 (-3.31)
4 -15.02 (-15.12)
5 -7.54 .. -7.59 (-7.65)
6 -7.56 .. -7.62 (-7.68)
7 -7.54 .. -7.65 (-7.68)
8 0 (0)

IC4 JRC4558D
1 -7.56 .. -7.62 (-7.68)
2 -7.59 (-7.6)
3 -7.55 (-7.62)
4 -15.02 (-15.12)
5 -7.72 (-7.68)
6 -7.8 (-7.74)
7 -7.71 .. -7.98 (-7.74)
8 0 (0)

IC5 JRC4558D
1 -7.52 .. -7.67 (-7.68)
2 -7.54 .. -7.65 (-7.67)
3 -7.51 .. 7.63 (-7.65)
4 -15.02 (-15.12)
5 -6.49 (-6.91)
6 -6.55 (-6.99)
7 -6.56 (-6.98)
8 0 (0)

IC6 JRC4558D
1 varies (varies)
2 -7.14 .. -7.23 (-7.23)
3 approx -6 .. -8 (-7.3)
4 -15.21 (-15.28)
5 -7.14 .. -7.23 (-7.23)
6 -7.15 .. -7.25 (-7.25)
7 varies (varies)
8 0 (0)

IC7 CD4047BE
1 -6.98 (-7.17)
2 -8.31 (-8.14)
3 -8.25 (-8)
4 0 (0)
5 0 (0)
6 0 (0)
7 0 (0)
8 -15.21 (-15.28)
9 -15.21 (-15.28)
10 -7.84 (-7.51)
11 -7.84 (-7.5)
12 -15.21 (-15.28)
13 -6.95 (-7.11)
14 0 (0)

IC8 MN3005
1 0 (0)
2 -7.84 (-7.5)
3 -10.15 .. -10.46 (-11.56)
4 -10.15 .. -10.46 (-11.56)
5 -15.21 (-15.28)
6 -7.84 (-7.5)
7 -6.81 .. -7.12 (-8.55)
8 -14.28 (-14.31)

IC9 MN3005
1 0 (0)
2 -7.83 (-7.5)
3 -11.83 .. -12.09 (-10.9)
4 -11.81 .. -12.05 (-10.89)
5 -15.21 (-15.28)
6 -7.84 (-7.51)
7 -7.71 .. -7.98 (-7.74)
8 -14.24 (-14.29)

REG L7915CV
I -15.2 (-15.28)
O -17.77 (-17.93)
G 0 (0)

Q1 2N5087
C -13.42 (-13.67)
B 0 (0)
E 0 (0)

18.05vDC isolated supply (18.24vDC isolated supply)
Clock Frequency Range: 75.76kHz to 8.94kHz (76.97kHz to 8.35kHz)

Audio samples​

I have recorded the following:

• input 250Hz sine wave
• Test Point 1 (sounds good)
• Test Point 2 (with high-pitched noise)
• Test Point 3 (with more high-pitched noise)
• example output (with shhh-shhh noise)
• adjusting BIAS 1 while monitoring TP2 (high-pitched noise does not go away).

https://soundcloud.com/vurguuz%2Ftotal-recall-2024-troubleshooting

Frequency analysis​

The high-pitched noise in the Test Points is in line with the 8.94 kHz clock frequency:

Modifications​

• Thinking that my 240pF cap is off by too much, I removed it, added socket terminals and auditioned other 240pF caps. The square wave period at pins 10 and 11 of the 4047 was always in the 110us .. 112us range. This is lower than referenced on David Morrin's calibration page, but I guess this is because my Delay pot is a bit shy of 100k.
• The closest 100KB pot I had was 94k, which is what I used for the Delay pot.
• In some places I used physically bigger caps than what was called for, opting to spend my existing parts inventory instead of spending money on smaller parts
• The relay bypass switching is completely based on pedalpcb's project, but with a smaller relay that was available to me
• Lead dress is not my strong suit, but the wires to and from the in/out jacks are screened with a ground connection at one side

Photos​

In conclusion​

Please let me know if you have any ideas on what I can check and try to get this thing running cleanly, it really would mean so much to me.

Thanks!

 

[jwin615]

Do you have another 3005 to try? TP1 and TP2 are on either side of that 3005 so....
Also double check for solder bridges on it and related nearby components.
Be sure to use ESD precautions with BBDs.

 

[tcpoint]

I'm wondering if you could be getting some resonant frequency from your 555 timer from your relay bypass. Do you get the high pitched whine at all delay settings?

 

[vires]

I just finished building one of these and have the exact same issues you present here. Did you manage to make any progress? I noticed that turning the delay time down the noise goes away (I think because it goes up into inaudible frequency range). But I'm still scratching my head on whether it's expected to have this noise at the test points. I don't have it at the output of the pedal.

More importantly I have a swishy white noise on the output of the pedal that follows the curve of any modulation present. Wondering if you also experienced this and if you've had any ideas/success troubleshooting. Thanks for your post here and any updates going forward

 

[Lorok]

Unfortunately, haven't had a chance to touch it yet. But some thoughts:

Do you have another 3005 to try? TP1 and TP2 are on either side of that 3005 so....

I have the second MN3005 from this build that I'm planning to try and swap it in. It is of course from the same supplier (StompBoxParts).

Also double check for solder bridges on it and related nearby components.

Will do, but the IC voltages don't show any unwanted bridges, I don't think.

I'm wondering if you could be getting some resonant frequency from your 555 timer from your relay bypass. Do you get the high pitched whine at all delay settings?

The 555 in the bypass is not actually oscillating here, right? It is for debouncing the trigger signal. The high pitched whine goes away at lower Delay knob settings (= higher delay frequencies).

But I'm still scratching my head on whether it's expected to have this noise at the test points. I don't have it at the output of the pedal.

Right, that's the same question I have. During calibration of the DM-3 there was no such whine. I tried ignoring the whine and just focusing on getting the clearest signal, but there was still too much woosh noise at the output in many knob positions.

More importantly I have a swishy white noise on the output of the pedal that follows the curve of any modulation present. Wondering if you also experienced this

Oh sure, definitely.

Having a look at the schematic, I'm wondering if it makes sense to replace R20 and R21 with a 5k trimmer as per the other MN3005 in this build and also the datasheet.

 

[vires]

Interesting about the 5k resistor. I'm not sure if that would affect the issue - there's also no 5k resistor in the older Total Recall build and every demo of it I see on youtube there is no white noise wooshing.

I may have made some progress though - I realized the noise on mine gets worse/better at various positions on the delay knob, at first I thought I have a noisy pot that probably just needs some de-oxit, but then realized that the modulation is essentially doing the same thing as turning the delay knob, and is bringing in and out noise at the same values that I see when I manually turn the delay knob. Is your noise issue consistent with this, and if so, any ideas to further troubleshoot/solve?

 

[Caedarn]

I've got this board in my queue so am eagerly following this thread. Just wondering - have you posted on the Madbean forums? I think Brian would weigh in if he saw the post?

 

[vires]

I actually managed to isolate the problem to a certain area of the board between test points 2 and 4, and there turned out to be a bad resistor at R26 (measured 12k when it's supposed to be 100k). I'll report back if my noise issue is solved upon replacing it.

It's a fun build! Make sure you have the correct regulator (it's listed wrong on the BOM but recently a note was added to the documentation regarding this). And also, there are some caps the 1uf Capacitors listed as 10 film, but there are some electrolytic some film needed (I figured this out looking at the photo).

I tried to register for the madbeans forum but didn't receive the activation email - tried with two different accounts. Would love to be a member there - I should ask Brian about it but I worry he's busy making cool stuff and don't want to bug him lol.

 

[Caedarn]

….

I tried to register for the madbeans forum but didn't receive the activation email - tried with two different accounts. Would love to be a member there - I should ask Brian about it but I worry he's busy making cool stuff and don't want to bug him lol.

Thanks for the tips. I’ve had trouble with the Madbean forum using the Safari browser. This may be completely unrelated to your issue but figured I’d mention it.

 

[bean]

I actually managed to isolate the problem to a certain area of the board between test points 2 and 4, and there turned out to be a bad resistor at R26 (measured 12k when it's supposed to be 100k). I'll report back if my noise issue is solved upon replacing it.

It's a fun build! Make sure you have the correct regulator (it's listed wrong on the BOM but recently a note was added to the documentation regarding this). And also, there are some caps the 1uf Capacitors listed as 10 film, but there are some electrolytic some film needed (I figured this out looking at the photo).

I tried to register for the madbeans forum but didn't receive the activation email - tried with two different accounts. Would love to be a member there - I should ask Brian about it but I worry he's busy making cool stuff and don't want to bug him lol.

I just changed the registration process to immediate activation rather than requiring and email and approved all outstanding registrations. This is a problem with either the forum software or the host: it simply refuses to email members now and then.

Anyway, as to @Lorok I too am suspicious of the relay bypass as a potential culprit. The high pitch noise and white noise are separate issues, I believe. Overall your voltages look good and it appears you are passing delay so that's all good.

If I were debugging this the first thing I would do is temporarily remove the relay bypass and check TP2 & TP3 again. I say this b/c I have never even tried this circuit with anything other than true bypass or the stock bypass. And, while it's certainly possible to have some white noise at the outputs of the BBDs they get reduced greatly at the expander portion of the circuit. If I'm reading this right, your high pitch noise is at the longest delay setting, correct? Or was it at any delay setting?

 

[jwin615]

I just changed the registration process to immediate activation rather than requiring and email and approved all outstanding registrations. This is a problem with either the forum software or the host: it simply refuses to email members now and then.

Anyway, as to @Lorok I too am suspicious of the relay bypass as a potential culprit. The high pitch noise and white noise are separate issues, I believe. Overall your voltages look good and it appears you are passing delay so that's all good.

If I were debugging this the first thing I would do is temporarily remove the relay bypass and check TP2 & TP3 again. I say this b/c I have never even tried this circuit with anything other than true bypass or the stock bypass. And, while it's certainly possible to have some white noise at the outputs of the BBDs they get reduced greatly at the expander portion of the circuit. If I'm reading this right, your high pitch noise is at the longest delay setting, correct? Or was it at any delay setting?

The Russian spam bots are coming for all the threads now...

 

[vires]

Turns out that resistor was fine - I learned resistors don't always measure their inherent value when in a circuit.

So I tried reflowing the solder and then just replaced the parts between test points 2 and 4. I also tried swapping out the MN3005 in IC9. All to no avail. Still open to suggestions. @Lorok I will stay tuned here in case your troubleshooting sheds any light.

@bean any suggestions for me to solve the white noise issue? Noise not present at TP2 but present at TP4. Link of resulting noise issue on pedal output in case it's helpful (sorry for the weird artwork - using an old band's soundcloud account) :

https://soundcloud.com/friendsandfarmers%2Ftotal-recall-test2

I also have the same high pitched noise at the test points as in Lorok's recordings for me it's present at the higher delay time settings and as you turn the delay time down the frequency disappears as it shifts up above 20khz. Not sure if the high pitch noise is related to the white noise. Would be good to know if the high pitch noise at the test points is supposed to be expected - if not, is it possible it could be related to the white noise issue?

 

[bean]

The Russian spam bots are coming for all the threads now...

Yeah, that's not gonna work. I cleaned it up. I'll just have to check more regularly to see if there any registration approvals needed.

 

[Lorok]

If I were debugging this the first thing I would do is temporarily remove the relay bypass and check TP2 & TP3 again. I say this b/c I have never even tried this circuit with anything other than true bypass or the stock bypass. And, while it's certainly possible to have some white noise at the outputs of the BBDs they get reduced greatly at the expander portion of the circuit. If I'm reading this right, your high pitch noise is at the longest delay setting, correct? Or was it at any delay setting?

Hey everyone, I am glad this thread is gaining traction.

I have removed the 555 bypass:



Here is a video of TP2 with no input as I adjust the Delay knob. You might have to turn it up a bit:

At a loss of where to go from here

 

[bean]

Hey everyone, I am glad this thread is gaining traction.

I have removed the 555 bypass:
View attachment 92766


Here is a video of TP2 with no input as I adjust the Delay knob. You might have to turn it up a bit:

At a loss of where to go from here

Well, that's not so good. Hearing some clock noise at the longest delay times AT THE OUTPUT of the BBDs is not abnormal because that's when they go into the audible range. But, the whole purpose of the de-emphasis filter and expander section after the BBDs is to push all noise down out of the audbile range as possible. What's happening here in the video is definitely abnormal. But, I'm not sure yet why it's happening.

I pulled my build out today to investigate further, but give me a day or so to report back. ATM, I don't think this is a design problem but I won't rule it out until I can confirm it.

 

[Lorok]

Just to make sure we’re on the same page: I’ll reiterate that the video is a recording of TP2 sound, and not the output of the pedal. The pedal’s output doesn’t have this noise, but I can’t calibrate it: there are very audible artifacts most of the time. I can record the whole calibration procedure and the result, if that will help.

 

[MichaelW]

Whoa, I didn't notice the new Total Recall was re-designed to look like the old school big box DMM. How cool is that? This post won't help but I love your enclosure

 

[vires]

@Lorok yea dig that enclosure. @MichaelW I agree - love that it’s just like the old big box.
Excited to hear any updates on a path forward!

 

[Lorok]

I had a chat with @vires, and it seems like we have different MN3005 chips: mine are Xvive from stompboxparts and vires' are supposedly original from an ebay seller. I think we can rule out:

• faulty MN3005s (since ours are different manufacturers with the exact same problem)
• my relay bypass (completely removed now)
• solder bridges on the ICs (the voltages seem to be in line with the build docs)