Dumbloid  [traced]

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Re: Dumbloid

Postby 1oldsidewinder » 15 Jun 2014, 17:17

Correct me if I'm wrong but wouldn't lowering the value of those resistors give Q1 and Q2 a much hotter bias? Do you suppose the designer is using them as boosts or to contribute to the distortion in some way? I've read in a couple of earlier posts that these changes seemed "arbitrary" but what if they're intentional?

My pedals are both modded SD-1's. One is the easy low-parts-count mod I shared in "Pimp My Cheap Pedal"; the other is much more complete but one thing I have not messed with is the buffers. Neither of them fizz or crackle although I do hear a transition as the LED seems to decay faster than opamp. YMMV
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Re: Dumbloid

Postby mmolteratx » 15 Jun 2014, 19:18

1oldsidewinder wrote:Correct me if I'm wrong but wouldn't lowering the value of those resistors give Q1 and Q2 a much hotter bias? Do you suppose the designer is using them as boosts or to contribute to the distortion in some way? I've read in a couple of earlier posts that these changes seemed "arbitrary" but what if they're intentional?

My pedals are both modded SD-1's. One is the easy low-parts-count mod I shared in "Pimp My Cheap Pedal"; the other is much more complete but one thing I have not messed with is the buffers. Neither of them fizz or crackle although I do hear a transition as the LED seems to decay faster than opamp. YMMV


The bias voltage is set by the 10k/10k voltage divider. The effect of the value of the base resistors on the bias is minimal. The "designer" just randomly swapped parts in and out.

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Re: Dumbloid

Postby Cannibal » 15 Jun 2014, 19:51

mmolteratx wrote:
1oldsidewinder wrote:Correct me if I'm wrong but wouldn't lowering the value of those resistors give Q1 and Q2 a much hotter bias? Do you suppose the designer is using them as boosts or to contribute to the distortion in some way? I've read in a couple of earlier posts that these changes seemed "arbitrary" but what if they're intentional?

My pedals are both modded SD-1's. One is the easy low-parts-count mod I shared in "Pimp My Cheap Pedal"; the other is much more complete but one thing I have not messed with is the buffers. Neither of them fizz or crackle although I do hear a transition as the LED seems to decay faster than opamp. YMMV


The bias voltage is set by the 10k/10k voltage divider. The effect of the value of the base resistors on the bias is minimal. The "designer" just randomly swapped parts in and out.


Rememer that lowering the 510k resistor on Q1 lowers the input Z, reducing the amount of treble going into the pedal and making the pedal respond better to guitar volume changes.
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Re: Dumbloid

Postby mmolteratx » 15 Jun 2014, 22:52

Cannibal wrote:
mmolteratx wrote:
1oldsidewinder wrote:Correct me if I'm wrong but wouldn't lowering the value of those resistors give Q1 and Q2 a much hotter bias? Do you suppose the designer is using them as boosts or to contribute to the distortion in some way? I've read in a couple of earlier posts that these changes seemed "arbitrary" but what if they're intentional?

My pedals are both modded SD-1's. One is the easy low-parts-count mod I shared in "Pimp My Cheap Pedal"; the other is much more complete but one thing I have not messed with is the buffers. Neither of them fizz or crackle although I do hear a transition as the LED seems to decay faster than opamp. YMMV


The bias voltage is set by the 10k/10k voltage divider. The effect of the value of the base resistors on the bias is minimal. The "designer" just randomly swapped parts in and out.


Rememer that lowering the 510k resistor on Q1 lowers the input Z, reducing the amount of treble going into the pedal and making the pedal respond better to guitar volume changes.


Yes, but not significantly enough with 150k at the input. That 100p cap to ground will have considerably more effect on the high end.

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Re: Dumbloid

Postby Ripdivot » 16 Jun 2014, 05:34

Enough talking about the farty decay, I thought it was time to record it. The following clip consists of 3 parts. The first section is played through my dumbloid clone on the breadboard with a strat through a deluxe reverb reissue dry with no effects or processing. The second part is played through the AN Big Bloom (borrowed from a friend) with a strat through a deluxe reverb reissue dry with no effects. The third part of the clip is played through the ANBB again but this time with some chorus, delay and reverb added post recording. In the first 2 parts you can hear how dynamic the pedals are. The effects were added to the third part to try and mask the farty decay of the ANBB. The first 2 sections of the clip clearly show the farty decay and it can be heard at the end of the third part as well. I like the sound but not the decay. I have found if you feed the pedal into a slightly dirty amp it masks the decay pretty well. I tried setting the pedals to sound as close as possible and I got pretty close but the ANBB is slightly brighter and has slightly more gain but you get the idea.

https://soundcloud.com/ripdivot/dumbloid-farty-decay
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Re: Dumbloid

Postby mmolteratx » 16 Jun 2014, 06:01

Ripdivot wrote:Enough talking about the farty decay, I thought it was time to record it. The following clip consists of 3 parts. The first section is played through my dumbloid clone on the breadboard with a strat through a deluxe reverb reissue dry with no effects or processing. The second part is played through the AN Big Bloom (borrowed from a friend) with a strat through a deluxe reverb reissue dry with no effects. The third part of the clip is played through the ANBB again but this time with some chorus, delay and reverb added post recording. In the first 2 parts you can hear how dynamic the pedals are. The effects were added to the third part to try and mask the farty decay of the ANBB. The first 2 sections of the clip clearly show the farty decay and it can be heard at the end of the third part as well. I like the sound but not the decay. I have found if you feed the pedal into a slightly dirty amp it masks the decay pretty well. I tried setting the pedals to sound as close as possible and I got pretty close but the ANBB is slightly brighter and has slightly more gain but you get the idea.

https://soundcloud.com/ripdivot/dumbloid-farty-decay


Yep. That's that op amp distortion we all know and (love or) hate.
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Re: Dumbloid

Postby Manfred » 16 Jun 2014, 07:00

Manfred wrote:Is the single clipping LED of the Dumbloid a common red LED.
I wonder because there are special 5V red LEDs availabel which conducting already at lower voltages.
The latch-up happens at first at the negative voltage output swing, so a 5V LED could make sense to avoid the latch-up.
Who knows about the applied LED-Type at the Dumbloid?


Nobody gave me any answer.
I wonder if the applied LED type is identified.
I would appreciate very much if anybody could answer my question.
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Re: Dumbloid

Postby Ripdivot » 16 Jun 2014, 15:20

Manfred wrote:
Manfred wrote:Is the single clipping LED of the Dumbloid a common red LED.
I wonder because there are special 5V red LEDs availabel which conducting already at lower voltages.
The latch-up happens at first at the negative voltage output swing, so a 5V LED could make sense to avoid the latch-up.
Who knows about the applied LED-Type at the Dumbloid?


Nobody gave me any answer.
I wonder if the applied LED type is identified.
I would appreciate very much if anybody could answer my question.


I can't answer your question but I can tell you this: I have tried every led and diode type I have as well as putting in multiple LEDs back to back to raise the break over point and none of it has helped. Yesterday I tried back to back LEDs and diodes (like in a tube screamer) in both stages and I was surprised it didn't help either. I thought for sure if there was clipping diodes in both stages it would solve the problem but it didn't. I am moving on to something else.

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Re: Dumbloid

Postby Manfred » 17 Jun 2014, 07:47

Ripdivot wrote:
Manfred wrote:
Manfred wrote:Is the single clipping LED of the Dumbloid a common red LED.
I wonder because there are special 5V red LEDs availabel which conducting already at lower voltages.
The latch-up happens at first at the negative voltage output swing, so a 5V LED could make sense to avoid the latch-up.
Who knows about the applied LED-Type at the Dumbloid?


Nobody gave me any answer.
I wonder if the applied LED type is identified.
I would appreciate very much if anybody could answer my question.


I can't answer your question but I can tell you this: I have tried every led and diode type I have as well as putting in multiple LEDs back to back to raise the break over point and none of it has helped. Yesterday I tried back to back LEDs and diodes (like in a tube screamer) in both stages and I was surprised it didn't help either. I thought for sure if there was clipping diodes in both stages it would solve the problem but it didn't. I am moving on to something else.


Thank you very much indeed.
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Re: Dumbloid

Postby 1oldsidewinder » 17 Jun 2014, 15:13

Ripdivot wrote:Enough talking about the farty decay, I thought it was time to record it. The following clip consists of 3 parts. The first section is played through my dumbloid clone on the breadboard with a strat through a deluxe reverb reissue dry with no effects or processing. The second part is played through the AN Big Bloom (borrowed from a friend) with a strat through a deluxe reverb reissue dry with no effects. The third part of the clip is played through the ANBB again but this time with some chorus, delay and reverb added post recording. In the first 2 parts you can hear how dynamic the pedals are. The effects were added to the third part to try and mask the farty decay of the ANBB. The first 2 sections of the clip clearly show the farty decay and it can be heard at the end of the third part as well. I like the sound but not the decay. I have found if you feed the pedal into a slightly dirty amp it masks the decay pretty well. I tried setting the pedals to sound as close as possible and I got pretty close but the ANBB is slightly brighter and has slightly more gain but you get the idea.

https://soundcloud.com/ripdivot/dumbloid-farty-decay


Nice playing. If you could post a clip with the LED lifted, we could eliminate it as a source of the nasty decay assuming the rattle is still there.

Also, AN has posted elsewhere that the Big Bloom uses a 1k5 resistor in place of the 1k8 for the HP filter which would raise the raise the cutoff from ~400 to ~500hz and account for the difference in tone.
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Re: Dumbloid

Postby Ripdivot » 17 Jun 2014, 16:34

1oldsidewinder wrote:
Ripdivot wrote:Enough talking about the farty decay, I thought it was time to record it. The following clip consists of 3 parts. The first section is played through my dumbloid clone on the breadboard with a strat through a deluxe reverb reissue dry with no effects or processing. The second part is played through the AN Big Bloom (borrowed from a friend) with a strat through a deluxe reverb reissue dry with no effects. The third part of the clip is played through the ANBB again but this time with some chorus, delay and reverb added post recording. In the first 2 parts you can hear how dynamic the pedals are. The effects were added to the third part to try and mask the farty decay of the ANBB. The first 2 sections of the clip clearly show the farty decay and it can be heard at the end of the third part as well. I like the sound but not the decay. I have found if you feed the pedal into a slightly dirty amp it masks the decay pretty well. I tried setting the pedals to sound as close as possible and I got pretty close but the ANBB is slightly brighter and has slightly more gain but you get the idea.

https://soundcloud.com/ripdivot/dumbloid-farty-decay


Nice playing. If you could post a clip with the LED lifted, we could eliminate it as a source of the nasty decay assuming the rattle is still there.

Also, AN has posted elsewhere that the Big Bloom uses a 1k5 resistor in place of the 1k8 for the HP filter which would raise the raise the cutoff from ~400 to ~500hz and account for the difference in tone.


Thanks! I am at work so can't post another clip. I won't waist your time because way back when I first bread boarded this circuit the first thing I tried was lifting the LED and it didn't help the farty decay. My circuit has the 1k5 resistor. The slight differences in tone just come down to component tolerances and control settings I think.
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Re: Dumbloid

Postby bloomz » 21 Jun 2014, 00:32

I guess I haven't sniffed enough corks..... :mrgreen:
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Re: Dumbloid

Postby Ripdivot » 21 Jun 2014, 03:21

bloomz wrote:I guess I haven't sniffed enough corks..... :mrgreen:


Are you saying you can't hear the farty decay in my clip? Seems very obvious to me.
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Re: Dumbloid

Postby IvIark » 21 Jun 2014, 04:03

Come on be fair, I bet if you'd handed over $900 in total buying the same $10 worth of components twice, psychoacoustics would make it sonic nirvana to you too!

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Re: Dumbloid

Postby mirosol » 21 Jun 2014, 08:21

Yup. The crappy decay is a feature. Which rather funnily makes not only a slight TS derivative, but a bad TS derivative.
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Re: Dumbloid

Postby Nocentelli » 21 Jun 2014, 11:50

I was curious about the decay, and watched the pete thorn demo carefully a couple of times to see if i could hear any fizz, and he doesn't allow a chord or single note to fade out even once.
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Re: Dumbloid

Postby 1oldsidewinder » 21 Jun 2014, 16:27

What I really find curious are the posts where guys have tried every possible combination of clipping diodes and it apparently hasn't helped. It seems like converting the pedal to diode clipping would solve the problem if the rattle was indeed a product of op-amp distortion. If someone was to replace the accent control network with a 1k resistor and add a pair of LEDs to the first stage, it would be a CJOD with a slightly different voicing; a pedal not known for *farty* decay. If I were to pursue this, I'd continue to look at the many other changes the designer made. Either that, or build a CJOD and voice it like the Dumbloid.
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Re: Dumbloid

Postby Ripdivot » 22 Jun 2014, 03:33

Nocentelli wrote:I was curious about the decay, and watched the pete thorn demo carefully a couple of times to see if i could hear any fizz, and he doesn't allow a chord or single note to fade out even once.


I noticed the same thing, He is being paid to demo the pedal though.
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Re: Dumbloid

Postby juansolo » 22 Jun 2014, 09:30

Ripdivot wrote:Enough talking about the farty decay, I thought it was time to record it. The following clip consists of 3 parts. The first section is played through my dumbloid clone on the breadboard with a strat through a deluxe reverb reissue dry with no effects or processing. The second part is played through the AN Big Bloom (borrowed from a friend) with a strat through a deluxe reverb reissue dry with no effects. The third part of the clip is played through the ANBB again but this time with some chorus, delay and reverb added post recording. In the first 2 parts you can hear how dynamic the pedals are. The effects were added to the third part to try and mask the farty decay of the ANBB. The first 2 sections of the clip clearly show the farty decay and it can be heard at the end of the third part as well. I like the sound but not the decay. I have found if you feed the pedal into a slightly dirty amp it masks the decay pretty well. I tried setting the pedals to sound as close as possible and I got pretty close but the ANBB is slightly brighter and has slightly more gain but you get the idea.

https://soundcloud.com/ripdivot/dumbloid-farty-decay


Yep that's the one. Nailed on. Glad I'm not going insane.
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Re: Dumbloid

Postby ggedamed » 22 Jun 2014, 17:34

1oldsidewinder wrote:What I really find curious are the posts where guys have tried every possible combination of clipping diodes and it apparently hasn't helped. It seems like converting the pedal to diode clipping would solve the problem if the rattle was indeed a product of op-amp distortion.
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