E.W.S Tri-Logic II Bass Preamp  [traced]

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uncleboko
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Post by uncleboko »

There seems to be so little circuitry to this, what are its advantages?

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Post by chicago_mike »

It sounds really good. Even through its simplicity. its very clean and has good output.

The circuit is also used inside active Xotic basses.
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Post by chicago_mike »

bluetube wrote:
chicago_mike wrote:signal hits the passive active switch before anything. Its a dpdt. top 2 lugs are one resisitor, bottom 2 are another and the middle lugs are the signal from the jack to the pcb. :D
That's one switching option similar to what I had in mind. :D The photos say otherwise though. :shock: Maybe they got it wrong in the factory or I need to get my eyes checked? :) :) :)

just checked a couple piccies.

Input Jack-Whitey wire-3PDT Switchey-Whitey wire-passive agressive Switchey-Whitey wire-PCB
:mrgreen:
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Post by bluetube »

chicago_mike wrote:
bluetube wrote:
chicago_mike wrote:signal hits the passive active switch before anything. Its a dpdt. top 2 lugs are one resisitor, bottom 2 are another and the middle lugs are the signal from the jack to the pcb. :D
That's one switching option similar to what I had in mind. :D The photos say otherwise though. :shock: Maybe they got it wrong in the factory or I need to get my eyes checked? :) :) :)

just checked a couple piccies.

Input Jack-Whitey wire-3PDT Switchey-Whitey wire-passive agressive Switchey-Whitey wire-PCB
:mrgreen:
Hey Mike did you notice anything odd about the P/A switch wiring based on the pix? :D

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Post by chicago_mike »

:D

I know, middle lugs are unused. :D

So...Actually its probaly putting a resistor either in parallel with the input to ground resisitor, or in series.?? Wait...NOt the to ground resisitor, but input resistor...had to look at some amps that have active / passive inputs. :slap:

I wonder if that DPDT is a criss-cross style switch.....you know...1 and 2 of one side and 2 and 3 of another.....I have a couple of those. I HATE'EM!!! :lol:
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Post by bluetube »

chicago_mike wrote::D

I know, middle lugs are unused. :D

So...Actually its probaly putting a resistor either in parallel with the input to ground resisitor, or in series.?? Wait...NOt the to ground resisitor, but input resistor...had to look at some amps that have active / passive inputs. :slap:

I wonder if that DPDT is a criss-cross style switch.....you know...1 and 2 of one side and 2 and 3 of another.....I have a couple of those. I HATE'EM!!! :lol:
Maybe it's a weird kind of DPDT, like the ones you have. If so, like you mentioned, it's switching the 100k resistor parallel to the 1M resistor (shunt to GND before the input cap). Some kind of impedance matching I guess. :mrgreen:

Mike do you have pot values? Maybe verify the resistors as well? Both existing and unknown? I'm color blind and the resistors are 1/8w. I probably got some values wrong. :D :D :D

Matt can you join the murder mystery? Help fill in the blanks? Pretty please? :hug: :lol:

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Post by chicago_mike »

50K pots :D
250K for master I think..I wish I still had mine.

I'll get to work on the resistors soon as I get back from my gig.out of state. :roll:
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Post by bluetube »

chicago_mike wrote:50K pots :D
250K for master I think..I wish I still had mine.

I'll get to work on the resistors soon as I get back from my gig.out of state. :roll:
No rush Mike. Gig on. :horsey:

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Post by pedalgrinder »

am i losing it or is there a schematic for this i can't see i wen't through the lists and looked at the pics and can't even get a parts list together. Are you guys doing or building something here i can't see????????
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Post by Bill_Mountain »

pedalgrinder wrote:am i losing it or is there a schematic for this i can't see i wen't through the lists and looked at the pics and can't even get a parts list together. Are you guys doing or building something here i can't see????????
There's a rough draft on page 5.

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Post by chicago_mike »

I'm gonna go thru the info tonight...finally!!!
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Post by bluetube »

chicago_mike wrote:I'm gonna go thru the info tonight...finally!!!
:horsey:

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Post by chicago_mike »

Uhh..what scale is the pcb at? I dont have mine anymore and want to print the one here. To test a physical proto..



EDIT: Nevermind! :D
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Post by bluetube »

chicago_mike wrote:Uhh..what scale is the pcb at? I dont have mine anymore and want to print the one here. To test a physical proto..



EDIT: Nevermind! :D
Mike are you going to build this? Ima send you a PDF version if you're up for it. :D

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Post by chicago_mike »

Yeah. I have time after my weekend gigs. :)
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Post by bluetube »

Allo allo! Attached are files for the gizmo in question. UNVERIFIED and INCOMPLETE. P/A switching not shown. I'll leave this part alone. There's a schematic floating around the net for your alternative P/A switching needs. Some part values unknown or unsure (represented with ??? on either the schematic or parts layout).

Suggestions and inputs are always welcome. Edit as necessary. Ready to transfer PCB pattern in PDF (1:1, A4 sized paper) and layout with schematic in JPG.
Attachments
ews trilogic2 PCB unverified incomplete.pdf
(20.79 KiB) Downloaded 288 times
ews trilogic2 parts sc unverified incomplete.jpg

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Post by chicago_mike »

TY!!

I'll check it out after the weekend. I'll be picking up some positive boards for my new uv etcher. :)
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Post by darmstat »

Thanks bluetube. This is a really good start. :lol:

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Post by Nikifena »

A month ago I get one xotic fretless bas for repair. This bass has the same PCB like this one. Just for fun I trace it.

The schematics is the same. Here is the missing parts based on the last schematics:
The feedback resistor between the gate and drain is 10Meg
The resistor in the opamps feedback wich limit the gain (24k???) is 24k (in series with the 200k trim)
There is no 2k4??? resistor near the middle freq switch. The capacitors for the middle are 100n and 47n


Niki

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Post by bluetube »

Nikifena wrote:A month ago I get one xotic fretless bas for repair. This bass has the same PCB like this one. Just for fun I trace it.

The schematics is the same. Here is the missing parts based on the last schematics:
The feedback resistor between the gate and drain is 10Meg
The resistor in the opamps feedback wich limit the gain (24k???) is 24k (in series with the 200k trim)
There is no 2k4??? resistor near the middle freq switch. The capacitors for the middle are 100n and 47n


Niki
Thanks Niki. OT, nice looper! :thumbsup

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