Access-312 Build Thread

[sr1200]

are all your jumpers in the right place?

 

[tskguy]

I soldered a bridge between pin 2 and 3. That should work right?

 

[3nity]

yes it will work but have you tried 1-2 and 3-4 ??
it would sound slightly different...
Thansk

 

[tskguy]

Hi all,

I figured it.... they all work great now!!  I was just being very stupid! Simple XLR wire issue.  This was after a good hour of trouble shooting. geesh.

Anyway thanks for the help!

Eric

 

[tfletchii]

hey guys I'm not getting audio and at the moment I only have new OP amps. If you could take a look and see if any thing looks off I'd appreciated it. I checked the power supply and it is running the 48v, 16+, 16- so it doesn't seem to be the issue. I'm only running two of the four preamps at the moment. I'm going to finish the other two when time & money allow.  Thanks again for every ones help. I know it is a big variable to have a new preamp build with a new OP amp as well but I guess you have to start somewhere...

I was thinking i could get whistle rocks ic to doa as a way to check the build since it is such a simple design. Has anyone done that?

 

[sr1200]

is your input tx oriented properly?  (is it grounding out on the board? did you leave a little gap between it and the board?)

if you have other DOA's try subbing them out.  For whatever reason, when i build the DOA's i always get 1 that doesnt work, even if its put together perfectly.

 

[tfletchii]

i don't believe I left a gap. If I did it was unintentional. I'll look into it. thanks

 

[sr1200]

Also, i hope thats just dust and not metal shavings all over the place on the board and in the case...

 

[tfletchii]

thanks again, its dust though. mixed with a little sunshine and it can be rather deceiving.

 

[3nity]

Tfletchii....
On your potentiometer, the green wire solder it to where the orange is and try it...you dont need to ground it..
Thannk you.

 

[tfletchii]

3nity, if you don't mind me asking, why is that? that is the ground slug of the pot. I guess I'm causing a ground loop then because the pot is grounded to the case.

also, I saw on page 5 where frazzman had the same issue with the pot. I'm sorry I didn't see it earlier. I've read through this build thread a few times and i made a mistake in not remembering.

 

[3nity]

Dont forget this is not a normal pot its a Rev log...
do it like told you and tell me.

 

[jsteiger]

Looks to me like the jumper for the 2622's primaries is wrong. It should be 1-->2 and 3-->4.

 

[sr1200]

For that tranny... yeah, that makes sense... Good spot.

 

[3nity]

However i tried it on 2-3 and it works on mines..

 

[tfletchii]

thanks jsteiger, I'll try it that way.

3nity, I did what you said (ran the green wire over to the orange) and it is passing audio but very little. Sounds like it is a ground problem to me but I think I bought the wrong pots so maybe that is whats going on. Here is the mouser link to the pots I bought.

http://www.mouser.com/Search/ProductDetail.aspx?R=RV16AF-10-15R1-B10K-0Cvirtualkey14860000virtualkey313-2000F-10K

thanks everyone for your help. yall are great

 

[3nity]

That is not a reverse pot.
Thanks

 

[jsteiger]

However i tried it on 2-3 and it works on mines..

It will work but should be primaries in parallel for a typical 312 style pre. 2-->3 is primaries in series which has about 6dB less gain from the transformer and higher Z.

The 10k pot will not keep the pre from working. It will work backwards, fully CW will be lowest gain, fully CCW will be max gain. Definitely will want to change this.

 

[buildafriend]

Okay.. So they worked great in my bed room.. but now im in the studio and they are giving me oscillations when they are cranked.. any thoughts on what it could be?

thanks in advance

 

[3nity]

Do you have internal psu?
well try moving the toroidal around.
thanks