[BUILD] CAPI VP2X~500 Series~Preamp Kit~Official Support Thread

shaun_curran · Feb 17, 2016

I just recently built 4 vp26 pre amps. One of them the output attenuater isn't doing anything. It passes signal fine and the stepped gain input knob works fine. Any Thoughts. I switched out the DOA with one of the pres that worked perfect and it still doesn't work. Where should I start my search for the problem?

Also, I have an issue with all 4 pres that sounded common to other people in this forum but I haven't seen any solution. The phase switch seems to cut all the low end and does something with the mid range. It's very obvious and I would never track anything with the phase button flipped with it the way it is. Not a huge deal but kind of a bummer.

These things sound so great though.

jsteiger · Feb 18, 2016

I would guess a bad solder joint on the t-pad or output transformer? The polarity switch will not change the frequency response at all if everything is built correctly.

shaun_curran · Feb 26, 2016

T pad?

jsteiger · Feb 26, 2016

t-pad = output attenuator

shaun_curran · Mar 1, 2016

Clearly I'm a newby. I figured that out. I resoldered everything on the board paying close attention especially to the output transformer and the t-pad everything looks good. I'm gonna order another couple of kits. So maybe I'll try to replace the t-pad with a new one. Maybe I have a bad one.

jsteiger · Mar 1, 2016

shaun_curran said:
So maybe I'll try to replace the t-pad with a new one. Maybe I have a bad one.

Very highly unlikely its the t-pad.

shaun_curran · Mar 1, 2016

Maybe I have c10 backwards. It doesn't have the bar indicating the negative side but I have it so the two ridges are one the bitten towards the ea2622. This is how It was in all of the pictures I saw.

jsteiger · Mar 1, 2016

shaun_curran said:
Maybe I have c10 backwards. It doesn't have the bar indicating the negative side but I have it so the two ridges are one the bitten towards the ea2622. This is how It was in all of the pictures I saw.

That will not make a difference either but, they are marked. If you look closely, there are some "-" going down the body inside of a larger arrow(s) that point to the negative end. Also the groove is nearest the positive end.

Sinkia · Apr 8, 2016

Hi there !

We have ordered 3 Capi VP26, done the build, and had our first session today !

Upright piano -> schoeps (AB mode) & U87 below the keys -> CAPI VP26..

The sound of those units are really great !!!

Thank for it !
Cheers up to you !

Spino · Apr 18, 2016

Finally had the time to build the VP26 and the GAR2520. It was great fun. Obviously enough (any tip here suggest not to go with both things built from scratch), the preamp would not work correctly. The closest 2520 that I could borrow is many kms away, so I thought I could try temporarly with a 2132 I had around. And it works! As suspected, the 2520 build got my eyes crossed

. But at least now I know where to look for.

Once again: great fun building it, great forum to read through.

Potato Cakes · Apr 20, 2016

Spino said:
Finally had the time to build the VP26 and the GAR2520. It was great fun. Obviously enough (any tip here suggest not to go with both things built from scratch), the preamp would not work correctly. The closest 2520 that I could borrow is many kms away, so I thought I could try temporarly with a 2132 I had around. And it works! As suspected, the 2520 build got my eyes crossed . But at least now I know where to look for.

Once again: great fun building it, great forum to read through.

It's really just practicing building the opamps. My first 3 or 4 attempts where failures because I went faster than I should have and didn't pay close enough attention to component placement, orientation, and had some solder bridges, which as you know is easy to do since you're cramming a bunch of stuff in a tiny space. My suggestion if you aren't already, is to use a fine solder tip and the thinnest solder possible. Give it a couple more tries and I'm sure you'll nail it.

No, Jeff does not pay me to tell other people to buy more stuff from his store.

Thanks,

Paul

jaminem · Apr 22, 2016

Cleaning:

I have 2 x VP28,26 & 312 and they all are suffering from a sort of reddish tarnish on the front panels, making them look dull. Any idea how I can clean them safely to bring them back to their black/white/blue former glory?

Was thinking about lighter fuel but I don't want to burn the silk screening off....

Thanks

slangrj · May 8, 2016

Newbie question:
I just got my VP26 kit and I've got the REV B.1 - is it the same as REV B?

59flame · May 28, 2016

have a vp28 that the green signal light stays on constantly. Unit works fine other then that. signal Light did not light constantly when first built but has started recently. Again all else works fine.

savingpandas · Jul 16, 2016

Alright gents hopefully someone can help me out. I just built the VP26 Rev B.1 variable gain with litz transformer and the red dot DOA and during the 12.1 Tests from the general assembly guide I got these readings on the respective sockets for the DOA (which should have been over 200 kOhm)
- and O 20 kOhms
+ and C 150 kOhms
all the others are over 200 kOhms though. I debugged every component to make sure they were in the right slot or orientated correctly, made sure there were no bridges and no cold solders, and made sure the switches were done as described in the trouble shooting tips along with the rest of the suggestions and am still at a loss. Anyone think they can point me in the right direction or share their unforseen errors? Thanks!

jsteiger · Jul 17, 2016

savingpandas said:
Alright gents hopefully someone can help me out. I just built the VP26 Rev B.1 variable gain with litz transformer and the red dot DOA and during the 12.1 Tests from the general assembly guide I got these readings on the respective sockets for the DOA (which should have been over 200 kOhm)
- and O 20 kOhms
+ and C 150 kOhms
all the others are over 200 kOhms though. I debugged every component to make sure they were in the right slot or orientated correctly, made sure there were no bridges and no cold solders, and made sure the switches were done as described in the trouble shooting tips along with the rest of the suggestions and am still at a loss. Anyone think they can point me in the right direction or share their unforseen errors? Thanks!

I think you are checking between opamp input - and O. That will be 20k since there is a 20k feedback R between those pins. The tests were described as +V and -V. Those are the voltage supply pins NOT the audio input pins.

Potato Cakes · Aug 1, 2016

59flame said:
have a vp28 that the green signal light stays on constantly. Unit works fine other then that. signal Light did not light constantly when first built but has started recently. Again all else works fine.

Do you have another IC to use for the LED control? Is it oriented correctly? Does it go away if you pull the IC? If everything is working correctly then I would see if the chip has not somehow gone bad. I had something like this when I first built one, but it was a faulty DOA I believe.

Thanks!

Paul

rshake87 · Aug 18, 2016

Hi guys! I too have the green light problem happening. When I power up the unit, it passes signal perfectly with good tone, however the green light stays lit until the gain knob is turned to the center position. It then turns off and functions normally. Is there any way to remedy this? Thank you.

blackartmixing · Aug 20, 2016

can someone help me with the transformer wiring for a Rev C VP26 please? the wires don't match up with the PCB or the support documents. i have, from left to right, black, red, grey, pink, purple, orange. photo attached

Potato Cakes · Aug 20, 2016

Those markings are for the Ed Anderson transformer. You have to go to Jeff's site and look at the table on Litz product page that shows which color lead of the transformer you have matches the label on your PCB.

Thanks!

Paul

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