Earthquaker Devices - Palisades  [traced]

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Manfred
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Post by Manfred »

I have another question: does the signal-phase stay the same when the mpsa18 is used inversely?
If so, then this could be the answer.
The signal-phase stay the same.

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modman
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Post by modman »

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Earthquaker Devices Palisades guts
Earthquaker Devices Palisades guts
Earthquaker Devices Palisades
Earthquaker Devices Palisades
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kmmoe
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Post by kmmoe »

Albru80's layout have now been confirmed over at tagboardeffects. There is still the mystery diode, but as both the pictures shown in this post by modman, and the comments over at tagboardeffects show, diffused red 3mm have been used by EQD, and sounds good.

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storyboardist
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Post by storyboardist »

Here's a perf/pcb layout for this. Pots are board mounted, switches are off board. Best fit is going to be in a 1790NS like the original.

Image

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POTL
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Post by POTL »

There are a couple of ideas for improving the scheme
1) The output buffer and booster must be interchanged, then in boost mode the output impedance will not change - so it is more logical
2) The input buffer is not to be disabled, but in the 3pdt button there are 2 pins connected between the sobo (bottom row, right and bottom pins, connect to the buffer, using the DPDT toggle switch)
This will enable the selection of a bypass, and in the operation mode of the overdrive we will always have a buffer at the input.
3) Volume potentiometer should be changed to A10K
4) Boost potentiometer should be replaced by A100K
this will give smoother adjustments

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storyboardist
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Post by storyboardist »

Got a comment on my Instagram from a guy who works for EQD who said "You have some discrete misses." So unless he's trolling (which I kinda doubt), we're close but not quiet there yet.


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kmmoe
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Post by kmmoe »

@ Storyboardist. It is an MPSA13 in the booster, not an MPSA18.

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Post by storyboardist »

kmmoe wrote:@ Storyboardist. It is an MPSA13 in the booster, not an MPSA18.
Fixed

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jalmonsalmon
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Post by jalmonsalmon »

storyboardist wrote:Got a comment on my Instagram from a guy who works for EQD who said "You have some discrete misses." So unless he's trolling (which I kinda doubt), we're close but not quiet there yet.

I think the schematic posted is more or less in the right ball park so maybe it has something to do with the boost :scratch:

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kmmoe
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Post by kmmoe »

I have gone through the whole schematic one more time, and I really can't find anything that does not add up. I have measured all the connections I can't see clearly, measured all the caps and resistors in the original pedal, and it all checks out. Just beware that the original pedal uses a B100K volume pot, not a A100K, if you want it correct.

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Manfred
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Post by Manfred »

What makes to me, nevertheless, taken aback the fact that the input buffer headroom is noticeably reduced when the transistor works in the inverse operation mode, the buffer output signal starts clipping at a input voltage of 250 Millivolts.
In the normal operation mode the output signal starts clipping at a input voltage of 2.6 Volts.
:scratch:

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Nick123
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Post by Nick123 »

So it could be the twisted designers logic - without buffer is actually the "buffered" sound ? :scratch:

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Visualdistortion
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Post by Visualdistortion »

Some people reported issues with Tagboard build, any news on a "more" verified schematic?
I wanna make it
I wanna make it wit chu
(again and again and again)

French... sorry ;)

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dahliacorpse1
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Post by dahliacorpse1 »

I built this from tagboard. Everything works but the boost. The boost volume goes to just under unity gain. Everything else seems to work well though

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Post by Visualdistortion »

Nobody solved the booster issues of the Tagboard vero?
I will love to add it to my rig
I wanna make it
I wanna make it wit chu
(again and again and again)

French... sorry ;)

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Post by slackshampoo »

V2
:beatdeadhorse:
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D3CEC56E-87BC-4BA3-8F5C-711AE384BDDC.jpeg

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slackshampoo
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Post by slackshampoo »

A couple changes in V2. Buffer Q C & E are reversed compared to the schematic floating around. The 1k R and .1 uF C order are reversed and the switch terminal (bypass path) is between them. Boost has a filter cap at the input. Everything else seems to match up at first glance so that's all for now, gotta watch fight night at MSG.
Buffer section
Buffer section
Boost
Boost
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filtering cap on boost input
filtering cap on boost input
buffer changes
buffer changes

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Manfred
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Post by Manfred »

Thanks for tracing der Version 2.
Buffer Q C & E are reversed compared to the schematic floating around.
Maybe the reverse mode of Q in version 1 was indeed an error in board design.

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Post by slackshampoo »

Yeah could be, pretty odd. Seems like a pretty large mistake to make all the way to production. If it was a printing error it could easily be fixed by populating Q1 backwards.

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jalmonsalmon
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Post by jalmonsalmon »

Does Buggs PCB need to have that fix?

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