[BUILD] GIX-51X tube preamp

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mhuss

Active member
Joined
Nov 21, 2011
Messages
44
Location
PA/USA
Thanks again, Rodney.  This would be a lot easier to troubleshoot  if I had my 51x rack & PS in the same room as my workbench.  :-\
 

mhuss

Active member
Joined
Nov 21, 2011
Messages
44
Location
PA/USA
I got a 7-pin XLR for my test jig from JS so I could bring my 51x PS down to the workbench and plug it in.  :)

On both units, in MIC mode with both gains maxed, I'm getting about 43 dBv gain (~48mv in / ~6v out) from the first grid of V1 (IN-SEC+) to the plate of V2 (OUT-PRI+) . Is this low or in the ballpark?

Thanks...
 

maq3396

Well-known member
Joined
Mar 20, 2013
Messages
158
Having been working on this for some time now but am having issues with it.

When powered on it is initially quiet but over 10 seconds or so this buzz begins.

Buzz tends to oscillate a bit....sounds like it is changing gears!

Volume of the buzz does not change with the position of any of the front panel controls.

It passes audio very well

Redone all solder joints and isopropyl ' ed everything.

Any help would be appreciated as I love the sound of this!

https://soundcloud.com/mac-quantz/voice-170217-1mp3

Thanks
Mac
 

maq3396

Well-known member
Joined
Mar 20, 2013
Messages
158
ok....seems to have resolved by itself!

Left it on overnight and the buzz has completely dissipated

Not the tubes as I tried a different set and they were very quiet as well.

Interesting as it has spent many hours on before!

At any rate I am a happy boy today!

 

delaystomper

Member
Joined
Jan 10, 2015
Messages
5
Hi greetings to everyone ! I know i know im so behind on this project but i just recently joined the 500 series group  just got my rack a few days ago and im looking to build some modules . Im very interested on this gix-51x project , is there any one here that can tell me where to find the pcb's for this unit. I checked the schematic and layout but there is no pcb transfer on it . I know its been here for a while but not all of us were able to jump aboard on it earlier i will  appreciate any help
Thanks
 

mtw

Well-known member
Joined
May 26, 2008
Messages
64
Location
Bay Area - CA - USA
I just bought a pair of half finished kits from another DIYer.

The additional bypass cap (the one on the underside of the board) that the seller sent me are too fat to fit between the PCB and the bracket. No problem, I bought some new ones.

I went to Mouser and got 10 of these: Multilayer Ceramic Capacitors MLCC - Leaded RAD 250V 0.1uF X7T 10% LS:5mm

However, they look nothing like the round caps I've seen in others' builds. The specs are same (0.1ufF/ 100nF and 250V rated) but they look more like little bypass caps than the larger "disc" type.

Will these caps I bought work for this build?
 

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