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Old 13th February 2013, 10:35 AM   #1101
Zen Mod is offline Zen Mod  Serbia
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yeah

and you would hear that difference ?
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Old 13th February 2013, 10:55 AM   #1102
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Zen Mod

would you please correct me If I am wrong
Is Z in of UGS V3 about R In when used with unbalanced Input and about 2 x R In when used with balanced Input
can I Increase R In If I need more UGS Z In because I like to lower output value coupling cap at source
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Old 13th February 2013, 11:01 AM   #1103
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yes , you can , but only up to some value

I would not go much above 47K

even if cascoded Jfets are in case , they don't like too much of impedance in feeding (feedback or not ) paths
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Old 13th February 2013, 12:04 PM   #1104
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thank you

would you please check out Z In values - are they correct
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Old 13th February 2013, 02:13 PM   #1105
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roughly - what's the value of series resistor , that's input impedance per leg ; that's precise enough for most purposes

inputs are inverting , ref to correspondent outputs ; so they're acting as virtual gnd (looking from preceding stage) and there lies the reason for that simplicity

you meant on that ?
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Old 13th February 2013, 02:23 PM   #1106
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thank you Zen Mod
so when used Pot before UGS the load for my source Is R POT parallel to R IN UGS
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Old 13th February 2013, 02:47 PM   #1107
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sort of

whatever - going much above 10K for pot is way to introduce cable irregularities in game

almost any decent source nowadays is having max output impedance in range of max 600R , so capable to drive 10K pot

if not , then quality of source in question isn't on par with UGS
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Old 13th February 2013, 09:01 PM   #1108
rade95 is offline rade95  United States
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Quote:
Originally Posted by samoloko View Post
when using unbalanced mode UGS v3 with unbalanced In+ to unbalanced Out+ Is It correct to ground In- and Out-
at first I was using UGS v3 with not grounded In- and Out- then I grounded In- and Out- and got more gain but for me the sound become somehow unplesant
are R In and R FB and R G the most critical resistors which got to be of highest quality

UGS adventures
thanks samoloko, I know I saw that long post of Cheffs somewhere. It explains, well, almost everything. :-)
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Old 13th February 2013, 09:09 PM   #1109
rade95 is offline rade95  United States
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Quote:
Originally Posted by Maousse View Post
I use my Cheff's UGS All Inclusive in unbal/unbal config for now.
My amp has 29dB gain, that makes 1.2V sensibility.

Cheff's UGS gain is enough for my configuration, I guess it could be OK for you too.

About PCB's, the Gerber Files are on the site liked on my previous post. But cost can be high for just one set. I have a spare full set if you need (I keep it for my old days ^^)
Maousse, I would like to buy that spare set of PCBs. Please let me know and PM me. Looked at the gerbers, still cannot find UGS module and the UGS PS (+-24V dual) gerbers. What file names I should be looking for? The thing is I would like to re-design the PS PCB so that it can fit a non-EU transformer like the one you see in my PS picture. Also it would be nice to re-design the pin layout of the UGS module so that we could fit single JFETs instead of those hard to find duals. What do you think?
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Old 14th February 2013, 12:41 PM   #1110
Maousse is offline Maousse  France
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rade95, you've got PM

Gerbers for Cheff's All Inclusive version is at http://psykok.dyndns.org/diy/preamp_.../GerbersCG.zip

Simple version (the PCB you actually have) are at http://psykok.dyndns.org/diy/preamp_.../UGSGerber.zip

Last edited by Maousse; 14th February 2013 at 12:44 PM.
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