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Re: EH - Bass Micro Synth
Posted: 03 Nov 2010, 18:29
by S. Thompson
tuemmueh wrote:There seems to be some incorrect information around ...
According to the factory schematic, the following parts need to be changed for the bass-version:
C6=2u2 (1u)
C7=1u (0.47u)
C8=0.1u (0.056u)
R62=12k (2k2)
Thank you so much for this information. Everywhere else I've been reading the wrong information.
By the by, would you happen to know what handles the maximum output of the voices on the pedal? The original signal voice and square wave can match or exceed the volume of the input signal. The sub-octave and octave voices come no where close to being as loud though. There has to be a simple way to make the volume of the voices more uniform... I'm just not sure how.
- Steve
Re: EH - Bass Micro Synth
Posted: 05 Nov 2010, 14:57
by the_ungod
Hi,
Does anyone has a layout for the new version?! Just one pcb?!
^Thanks
Re: EH - Bass Micro Synth
Posted: 08 Nov 2010, 14:57
by S. Thompson
the_ungod wrote:Hi,
Does anyone has a layout for the new version?! Just one pcb?!
^Thanks
I believe all the components on the XO version are surface mount, but I'm not sure how much the actual circuit has changed.
Has anyone messed with the diodes for the octave section? I know
Shotgunn mentioned swapping the octave diodes out for 1N34A germaniums and getting a sort of octavia sound.
I'd love to do this, but which diodes should be switched? I'm trying to trace through the schematic to determine, but if anyone knows off-hand, let me know.
Once I get done with all of these modifications, I'll probably post something up on my site detailing each. So far, the most functional has been replacing the stock LED with a bi-color one that changes between red and green based on if the effect is in bypass or not.
- Steve
Re: EH - Bass Micro Synth
Posted: 09 Nov 2010, 15:08
by borislavgajic
S. Thompson wrote:the_ungod wrote:Hi,
Does anyone has a layout for the new version?! Just one pcb?!
^Thanks
I believe all the components on the XO version are surface mount, but I'm not sure how much the actual circuit has changed.
Has anyone messed with the diodes for the octave section? I know
Shotgunn mentioned swapping the octave diodes out for 1N34A germaniums and getting a sort of octavia sound.
I'd love to do this, but which diodes should be switched? I'm trying to trace through the schematic to determine, but if anyone knows off-hand, let me know.
Once I get done with all of these modifications, I'll probably post something up on my site detailing each. So far, the most functional has been replacing the stock LED with a bi-color one that changes between red and green based on if the effect is in bypass or not.
- Steve
......I have do that with diodes....2 diodes ,and made them switchable.......not drastic changes for my taste.......but you can try that out and see.......
much better is foot pedal modification......hmmmm ...I have foot sw for switching trigger on and off.......
Boris
Re: EH - Bass Micro Synth
Posted: 10 Nov 2010, 03:58
by f-banks88
Hi I'm new here. I tried building two of this version, one for me and one for my friend. The reason I chose this version of the PCB was because it was only one board and It gave me some flexibilty on choosing which kind of power supply to use. I also decided it was more economical to use the NJM13700 instead of the CA3094, Mainly because from small bear the CA3094 costs $6.75, and the NJM13700 costs only $1.02 and does what two 3094's can do so it was only $8.16 worth of chips compared to $94.50. My problem I think I've got the pin outs converted correctly But I was wondering if any of you guys had tried this with any success. Also when I have it plugged in for testing I have to amplify the effected signal alot more compared to the bypassed signal. The sound I'm getting sounds like all of the voices are going at the same time. Like the sub octave, octave, guitar, and Square wave are all sounding but none of the faders do anything to affect the sound. also the trigger makes a high pitched squeal when pulled all the way down, and none of the frequency controls do anything. So if you guys have any trouble shooting ideas they would much appreciated.
Thanks! Alex
Re: EH - Bass Micro Synth
Posted: 22 Nov 2010, 16:11
by borislavgajic
check your build against schematic........and let us know......or post some photos of your build here

Re: EH - Bass Micro Synth
Posted: 27 Nov 2010, 12:59
by lufox15
f-banks88 wrote:My problem I think I've got the pin outs converted correctly But I was wondering if any of you guys had tried this with any success. Also when I have it plugged in for testing I have to amplify the effected signal alot more compared to the bypassed signal.
How you replace the CA3094? post a schematic please, i have tried that, viewing the new XO schematic version that i made, but i dont have any signal on the output, using transistors and the LM13700.
Sorry about my english.
Re: EH - Bass Micro Synth
Posted: 18 Dec 2010, 10:17
by fakcior
Hello!
I've found CA3094A. Can I replace CA3094 with it? It has got higher max voltage (24->36v). Will it be good?
Re: EH - Bass Micro Synth
Posted: 23 Dec 2010, 15:08
by borislavgajic
fakcior wrote:Hello!
I've found CA3094A. Can I replace CA3094 with it? It has got higher max voltage (24->36v). Will it be good?
I think that you can......

Re: EH - Bass Micro Synth
Posted: 21 Jan 2011, 22:54
by lufox15
Someone have new pictures of the XO version?
Re: EH - Bass Micro Synth
Posted: 26 Jan 2011, 19:05
by S. Thompson
So a couple of months ago (November, I think), I tried to swap out some resistor values to alter the maximum volume of each voice.
Well, something blew out because now the pedal sounds like it's gassy anytime I play anything. It just now occurred to me to come back and post here...
Here are the components I changed... the old and new values as well:
R23 8.2k->6.8k
R89 10k->8.2k
R42 13k->15k
The socketed OPAmps have been tested and they still seem to be functioning. The problem is that I really have no clue what could've blown from this change. Any help is appreciated!
- Steve
Re: EH - Bass Micro Synth
Posted: 28 Jan 2011, 06:42
by bls31401
Does anybody have a parts-list for this layout(or is it the same as the parts list already given for the boris layout)?
And what type of slider pots should be used for either of these micro synth clones?
Re: EH - Bass Micro Synth
Posted: 29 Jan 2011, 19:40
by O.B.Y
greaaatt..
i'll try to build this..
does anyone have problems with tis project?
Re: EH - Bass Micro Synth
Posted: 04 Feb 2011, 05:00
by lufox15
O.B.Y wrote:greaaatt..
i'll try to build this..
does anyone have problems with tis project?
if you're using the little pcb on the output part need to be ground a trace, cuz on the schematics the output a trace isn't grounded and the designer of the pcb have don't see the mistake.
Re: EH - Bass Micro Synth
Posted: 04 Feb 2011, 23:53
by borislavgajic
It seems like nobody manage to post some build results here...........
does that meen noone made working clone yet?

....except me?
my ca3094 layout works nice....best wishes, and hope to see somebody post finished one here
Boris
Re: EH - Bass Micro Synth
Posted: 06 Feb 2011, 02:00
by O.B.Y
lufox15 wrote:O.B.Y wrote:greaaatt..
i'll try to build this..
does anyone have problems with tis project?
if you're using the little pcb on the output part need to be ground a trace, cuz on the schematics the output a trace isn't grounded and the designer of the pcb have don't see the mistake.
oowwww...
i see.. so have you built this??
Re: EH - Bass Micro Synth
Posted: 10 Feb 2011, 18:54
by lufox15
O.B.Y wrote:lufox15 wrote:O.B.Y wrote:greaaatt..
i'll try to build this..
does anyone have problems with tis project?
if you're using the little pcb on the output part need to be ground a trace, cuz on the schematics the output a trace isn't grounded and the designer of the pcb have don't see the mistake.
oowwww...
i see.. so have you built this??
yep, works perfectly! but i haven't upload some photos. maybe later..., i'm searching for someone who can take more photos of the XO version cuz i think, that can be a better version and more cheap cuz use just 3 or 4 LM13700, that cost the half of a CA3094. i have drawn parts of the schematic.
Somebody help with photos!!!
Re: EH - Bass Micro Synth
Posted: 10 Feb 2011, 20:08
by borislavgajic
Re: EH - Bass Micro Synth
Posted: 11 Feb 2011, 03:09
by lufox15
well, thanks for the link borislavgajic, but i had seen that picture already, i wish more close pictures for confirm the schematics and complete the missing traces.
Re: EH - Bass Micro Synth
Posted: 13 Feb 2011, 09:28
by borislavgajic
lufox15 wrote:well, thanks for the link borislavgajic, but i had seen that picture already, i wish more close pictures for confirm the schematics and complete the missing traces.
there is one big enough!!!........you can see all values written on board
can someone post pictures of finished builds here?
cheers
Boris