weiss

500 rack & op-amp problems!!
« on: February 22, 2015, 10:40:07 AM »
I am hopelessly trying to get everything working. I have issues with my 500 rack by michal and two vp26 modules but no clue on how to solve them :-\

- First: When i run a clean signal through one channel of my vp26 preamps on channel one of the rack then i get the same signal just hi-cut on the second preamp right next to it. Is this an issue of grounding? Currently all grounds are set to Input pin 1 of each rack connector.

- Second: When i run a signal through one preamp and change the controls of the preamp next to it, it affects the signal of the first one. Let me give you an example: I route a guitar through the preamp and have each of the controls set to 12 o clock (mid-position). Some color is given to the signal, but not much. Now when i turn turn up the input of the second preamp (slot on the right) which actually gets no signal, it is distorting the guitar sound of the first preamp very much. Again issue of grounding?

- Third: I have three RED-25 opamps and three gar2520 opamps, all of them seem to act a little weird (i don't know how they should sound though). On lower input levels (see my post here) the signal gets distorted, it sounds very grainy and stuttered like spikes. when input is increased to about mid position it goes away and "normal" coloration begins.. (samples below, rename to zip)
I doubt it is an issue of the opamps, although i had to assemble them myself. What could be the issue here??

I just hope there is someone who can teach me what to do and how to get things working again!

thanks
weiss
« Last Edit: February 22, 2015, 02:49:37 PM by weiss »


psych60s

Re: 500 rack & op-amp problems!!
« Reply #1 on: February 23, 2015, 06:22:45 AM »
Hello

Could well be a grounding issue, as ground is probably the only "link" between the two channels?

Otherwise I can't see how a signal could be present at both outputs if you route it to only one channel

pucho812

Re: 500 rack & op-amp problems!!
« Reply #2 on: February 23, 2015, 12:21:55 PM »
before we get into the modules, lets make sure your rack and the power supply for it is working properly.

You can test continuity between the pins and the in and out connectors to make sure they are all correct and that you don't have wires crossed or whatever.

Then check and make sure that under load your outputting the proper voltages needed

lastly focus on each preamp individually before them as a pair.   pick a known working slot and test one at a time. That will help trouble shoot.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.

psych60s

Re: 500 rack & op-amp problems!!
« Reply #3 on: February 23, 2015, 05:45:33 PM »
Pucho is right, I was assuming the rack was working good.

Could seem ignorant but does the VP26 have a standard 500 wiring?

pucho812

Re: 500 rack & op-amp problems!!
« Reply #4 on: February 23, 2015, 06:18:32 PM »
Yes it does.
You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is.