Dumbloid  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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Leroy
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Post by Leroy »

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Leroy
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Post by Leroy »

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Looks Like a Zendrive to me, Jfets and Opamp....

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Post by IvIark »

Unless the power track is hidden under the IC, it's definitely a single channel IC. What are all those zero ohm resistors all about?
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Post by deltafred »

Leroy wrote:Looks Like a Zendrive to me, Jfets and Opamp....
I don't see enough (any) diodes unless they are on the track side of the board. Also I would have expected the jfets to be closer together.
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Post by IvIark »

Of course, I was thinking input/output buffers but it will just be the clipping mosfets won't it? Hmmm
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Post by deltafred »

IvIark wrote:Of course, I was thinking input/output buffers but it will just be the clipping mosfets won't it? Hmmm
I'm no expert, I just searched for Zendrive and came up with a Z-drive schematic https://www.freestompboxes.org/download/ ... &mode=view that has 3 diodes and 2 jfets and would expect them to be close together.

To me it looks like possibly discrete input and output buffers and some form of opamp hitting the rails for the clipping. What topology that is I have no idea.

Could always be wrong of course!
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Post by IvIark »

He could have always used a different clipping arrangement I suppose, but the positioning of the transistors makes me think the input and output buffers is more likely. If they were the clipping mosfets I'd expect them to be close together because their pins are interconnected.
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP

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Post by MoonWatcher »

deltafred wrote:I don't see enough (any) diodes unless they are on the track side of the board. Also I would have expected the jfets to be closer together.
I think they are under the main mass of wiring. The pot on the RH side is definitely wired to adjust gain in the negative feedback loop. If you look at the original, you can see the green wire connects to the lower RH side of the pcb. But there is no sight of the purple/magenta wire.

The clone is clearly labeled that the wire on the right most part of the board is the input. And the only other wire on the RH side terminates to ground.

One of the jazz/rock switch lugs seems to also be connected to ground. In the original, there are yellow wires from the tone pot and switch. It looks like the one for the switch is more on the LH side, and the one for the tone is down at the LH bottom, almost center. It also connects to the tone pot's wiper lug.

It looks like the volume pot's wires are all in the upper LH corner - red, blue, and orange in the original. So the other orange and other white will be for the tone pot.

The wires from the accent pot are all but totally obscured, so there's no way to determine if they are similar to the voice control on the Zendrive.

I think given the location of the pair of visible transistors that they are indeed input and output buffers. In the clone, the red output wire is right next to what I guess would be a 1uF or 10uF tantalum cap for the output. If they are both emitter or source followers, they should have a similar or same setup.

Hmm...I also notice that there's a small value ceramic cap at pins 1 & 2 of the op amp. So it's definitely a dual op amp given that pin configuration. And in the clone, I can barely see that a green wire connects to pin 1, so pin 2 must be connected in conjunction with the resistor above the wire on the RH side of the board. So pin 3 would be above that, and the input cap would then be to the right of it. Also in the clone, it looks like there is a trace running from that cap to the transistor in the upper RH corner.

A pair of transistors for buffers would explain the need for the extra caps beyond what a Zendrive would have. Things being obscured by the wiring make it impossible to tell if pins 6 and 7 are shorted like they would be in a Zendrive as well. But the transistor on the LH side makes sense in that orientation, too.

But the number and type of caps seems to correlate to a Zen-ish design. There are a pair of electro's for bias supply/filtering. There's another smaller electro near what would be the output buffer.

Also noticed - there seems to be a gray/white wire wrapping around the tone pot - where's that thing connect? :scratch:

It's going to take more photos to make an obvious determination. But I think we can safely say that this is a dual op amp with in and out buffers design based on what is seen. I have no doubt that any diodes for clipping would be buried under that pile of wires.

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Post by deltafred »

MoonWatcher wrote: I think they are under the main mass of wiring.
That would make sense.

I haven't studied the photos with the same level of attention that you have mainly because I have no intention of building one (I'm a bass player who doesn't use pedals any more), it is just interesting for me to see what it is based on.

It might be worth knocking it up on my prototype board just to see what all the fuss is about though once it is out in the open.
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Post by Nocentelli »

Can't see the pictures, or face going to TGP - How much are they asking for the "clones"? And since when has it become acceptable to openly trace and sell clones on TGP? I thought people had been banned from that place in the past for far less "unethical" behaviour.
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

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Post by crw414tele »

last time I looked it was about half the cost of the real one. Hate to think what it would cost to have it sent to Australia. I most likely wouldn't build one even if a circuit came out , I've too many overdrives now but am still curious what it is based on as I have plenty to learn about effects building/design
Can't see the pictures, or face going to TGP - How much are they asking for the "clones"? And since when has it become acceptable to openly trace and sell clones on TGP? I thought people had been banned from that place in the past for far less "unethical" behaviour.
I thought so too.

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Post by amplifiednation »

Don't miss the crystal lattice under the board, It wouldn't show up in my photos.

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Post by 1oldsidewinder »

MoonWatcher wrote:
Also noticed - there seems to be a gray/white wire wrapping around the tone pot - where's that thing connect? :scratch:
I'm guessing the grey wire leads to the accent control and that "accent" may be something other than a ZD style voice control. Maybe it affects the range of the tone control like the presence trim-pot on the KoT.

Also, doubt there will be any more pics coming. They were only intended to show the accuracy of the clone. AN has posted elsewhere regarding his admiration of Shin and that he will never, ever tell.

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Post by MoonWatcher »

Nocentelli wrote:Can't see the pictures, or face going to TGP...
Me either, but someone chimed in on another site who is a regular there, and it appears that the clipping diodes are LED's.

So we have what appear to be input and output buffers, and LED clipping. It seems that the template used was not a Zendrive but a CJOD.

I would have to guess that the bulk of the alterations away from YATS would probably be in the tone circuit. All 3 lugs on the tone pot are used, and only 2 would be necessary with a Zen tone circuit. The jazz/rock switch connects to ground, so it must be adding in another cap.

And I guess the accent thing is still up in the air if this isn't a Zendrive. But there are so many ways that the TS tone circuit can be modified that it's wide open. Something to give that "string squeak" or whatever those guys refer to it being (note definition? :hmmm: ) so maybe it's like a presence-type of tone circuit.

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Post by IvIark »

It won't come from AN but someone else is doing it anyway
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP

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Post by MoonWatcher »

1oldsidewinder wrote:Also, doubt there will be any more pics coming.
All we need for a good idea is what the tone and accent pot values are, most likely. Anyone who owns one can measure them as they don't lie under the goop. If the tone pot is 20k, that probably tells a lot. If the accent pot is a really low value like 1K or less, then it is probably some sort of presence-type thing, but not necessarily like for the KOT.

Tone/accent and jazz/rock could all be variations on the stock TS tone circuit, right? From what I see with the wires that are visible, it kind of makes sense. If pin 6 connects to the tone pot's 3rd lug, it lends clues to that as well. And if pins 6 and 7 are connected with 1k, well... :idea:

Under further inspection going by the pics, it looks like everything to do with tone/accent and jazz/rock all connect around pin 6. Going by both the original and the clone, it looks like the jazz/rock wire is on the LH side of the board. So the wiper from the tone pot is buried more near the LH side of the op amp, and I think a wire from the accent pot leads up there, too.

So it looks like all of the tone/eq adjustment happens at U1b.

This thing is really looking like YATS/cjod/Landgraff/Boiling Point. What the Dumble pedal guys like about it are all un-Zendrive types of things.

If my hunch is true, is this the first of these that isn't in a swirly paint box? :D

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Post by 1oldsidewinder »

MoonWatcher wrote:
1oldsidewinder wrote:Also, doubt there will be any more pics coming.
All we need for a good idea is what the tone and accent pot values are, most likely. Anyone who owns one can measure them as they don't lie under the goop. If the tone pot is 20k, that probably tells a lot. If the accent pot is a really low value like 1K or less, then it is probably some sort of presence-type thing, but not necessarily like for the KOT.

Tone/accent and jazz/rock could all be variations on the stock TS tone circuit, right? From what I see with the wires that are visible, it kind of makes sense. If pin 6 connects to the tone pot's 3rd lug, it lends clues to that as well. And if pins 6 and 7 are connected with 1k, well... :idea:

Under further inspection going by the pics, it looks like everything to do with tone/accent and jazz/rock all connect around pin 6. Going by both the original and the clone, it looks like the jazz/rock wire is on the LH side of the board. So the wiper from the tone pot is buried more near the LH side of the op amp, and I think a wire from the accent pot leads up there, too.

So it looks like all of the tone/eq adjustment happens at U1b.

This thing is really looking like YATS/cjod/Landgraff/Boiling Point. What the Dumble pedal guys like about it are all un-Zendrive types of things.

If my hunch is true, is this the first of these that isn't in a swirly paint box? :D

I just threw the KoT thing out as an example. Probably more likely accent alters the frequency of the TS's C6/R9 pair. It's kind of funny that the LED mode on these kind of boxes is usually referred to as "Marshall" or "Plexi". Interesting that so many users insist that they're hearing Dumble. Power of suggestion? Then again, there seem to be a lot of different sounds that can be had with a D style amp. I feel an epic SD-1 mod comin' on!

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Post by Nocentelli »

1oldsidewinder wrote:AN has posted elsewhere regarding his admiration of Shin and that he will never, ever tell.
!?

Seriously? He'll knock out a "limited number" of half-price clones to demonstrate his admiration?
modman wrote: Let's hope it's not a hit, because soldering up the same pedal everyday, is a sad life. It's that same ole devilish double bind again...

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Post by bloomz »

Pretty darned nice of him to post that gut shot.

Seems the consensus is - it's not a Zen like so many predicted (not necessarily here). It's nicer to hear from experts with more information and less conjecture and unqualified opinions.

I don't really care if it was, but it's interesting tho. I just am looking forward to getting mine

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Post by platinum321 »

Bloom he did not post them Lucket did. I don't think he had any intention of posting them. Wake up. After they were posted he made out like he was the one who posted and says Merry Christmas. Oy! Rediculous.

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