[BUILD] CAPI VP28~500 Series~2-Stage Preamp~Official Support Thread

[jsteiger]

Question for the people who have these:

I'm thinking about getting a pair of these to use mostly in line mode, possibly as part of a mastering chain, and I'm curious if when you're in Line mode, does that defeat phantom if you accidentally turn phantom on?

The current Rev C boards have a 48V defeat for when you are in line mode. The previous Rev B.1 does not.

 

[Ricardus]

The current Rev C boards have a 48V defeat for when you are in line mode. The previous Rev B.1 does not.

Awesome. So is RevC a new thing that will be available when you have these in stock again or have you sold RevC previously?

 

[jsteiger]

Awesome. So is RevC a new thing that will be available when you have these in stock again or have you sold RevC previously?

These are currently in stock and we are currently shipping the Rev C boards.

 

[Ricardus]

Guys - quick question: I had to pull the brown transformer lead and unfortunately could not desolder the tiny hole so I soldered back to the top of the hole. Is this going to be a problem?

Do yourself a favor and get yourself some Solder Wick, and a solder sucker. Then watch a few videos on how to use them, and removing solder from that hole will be really easy.

 

[Bopshizzle]

Hello!

I just finished my first VP28 build, and it is working and sounding great despite very little past soldering experience. Thanks for the great kit and advice in this thread.

However I have two minor quirks I am wondering about:
1. The Front LEDs (not the green signal LED) only stay on for a few seconds before they flicker and turn off. Seems to last longer if I have more of them turned on. Is this bad soldering, or shorting to the ground plane or something else?

2. The octave toggle switch for the HPF makes a faint ground hum when I touch it. Not a huge problem, but is there anything I can do to remedy?

 

[jsteiger]

Hello!

I just finished my first VP28 build, and it is working and sounding great despite very little past soldering experience. Thanks for the great kit and advice in this thread.

However I have two minor quirks I am wondering about:
1. The Front LEDs (not the green signal LED) only stay on for a few seconds before they flicker and turn off. Seems to last longer if I have more of them turned on. Is this bad soldering, or shorting to the ground plane or something else?

2. The octave toggle switch for the HPF makes a faint ground hum when I touch it. Not a huge problem, but is there anything I can do to remedy?

Very odd behavior for both issues. I've never experienced either. Maybe its a rack thing? Maybe misplaced parts near Q1 and/or bad solder joints there or on the LEDs.

 

[leanlowkey]

i have a question about the vp28.

if im using a pair for my mix bus.. do i have to install the push switches since i dont need 48v or the pad or even the mic button. If their not installed does everything still work and would be act as if they were not "pushed" in

thanks

 

[jsteiger]

i have a question about the vp28.

if im using a pair for my mix bus.. do i have to install the push switches since i dont need 48v or the pad or even the mic button. If their not installed does everything still work and would be act as if they were not "pushed" in

thanks

All switches need to be installed.

 

[leanlowkey]

ok thank you! i figured but thought id ask

 

[oongbac]

My 3rd unit doesn’t work when phantom switch is ingaged

I should check it tomorrow. It’s quite late here in S.Korea. Have a good day diyers!

 

[oongbac]

Now it's a fully working unit. The usual suspect was mic/line switch. Maybe I soldered too short with that to avoid overheating.

Happy with the easy fix and sound as always!

 

[Oldmansantiago]

The kit I received has some caps values changed out. The two ceramic caps that should be 68 pF (C14 on the BOM) and 82 pF (C5 on the BOM). aren't in the kit, and instead I've got one 1.2 nF and one 410pF cap. These are wildly off from the spec'd values, has anyone else run into this? I've got some 68pF and 100pF caps lying around I could sub in, but I'm wondering if this was an error or a legitimate change.


edit: Magnifying glasses have proved me wrong, just some rough printing on the cap + bad lighting!

 

[leanlowkey]

anyone know where to get a new vp28 faceplate? purchased a couple off a friend that has the old faceplate and knobs.

 

[jsteiger]

anyone know where to get a new vp28 faceplate? purchased a couple off a friend that has the old faceplate and knobs.

Yeah, here. Classic Audio Products, Inc.

 

[Quantum J Audio]

anyone know where to get a new vp28 faceplate? purchased a couple off a friend that has the old faceplate and knobs.

If you purchase I’d be interested in buying your old knobs. I lost one.

 

[leanlowkey]

currious if I can swap out the transformers with some cinemag 3301. and if anyone knew the wiring diagram since the 3301 have 8 wires and not 6 like the transformer on the vp28. also if its possible to swap the input ca2622 with a re0887

thanks

 

[hasanova]

currious if I can swap out the transformers with some cinemag 3301. and if anyone knew the wiring diagram since the 3301 have 8 wires and not 6 like the transformer on the vp28. also if its possible to swap the input ca2622 with a re0887

thanks

You're basically re-creating a mod done by Frank DeMedio, just like the pre's for the custom console he built for Wally Heider Recording Studio 4. He replaced the (1:7) AP2622 for a (1:8) RE-0887.

The first version of the Heider pre's Jeff built, were modeled after these, but he used two CM-3301's on the output. Now he uses two platinum 2503-Litz. Frank left the stock 2503 on the card.

Wiring --> maybe ask CineMag for a datasheet?

 

[bsaurbs]

I just got my 2nd VP28 and got a 100uf electrolytic cap for C9, which is supposed to be 120uf in the BOM. Anyone have insights into this? My other VP28 (version B.1) has the correct value (120uf).

 

[Bopshizzle]

I just got my 2nd VP28 and got a 100uf electrolytic cap for C9, which is supposed to be 120uf in the BOM. Anyone have insights into this? My other VP28 (version B.1) has the correct value (120uf).

Same here! I think my last batch (Rev C) had the correct cap, but this one has the same cap as yours. Sent Jeff an email, but (understandably) no reply during the holidays.

I'm a bit of a newb, could anyone chime in to verify that this is safe to use despite the value differences?

 

[jsteiger]

I just got my 2nd VP28 and got a 100uf electrolytic cap for C9, which is supposed to be 120uf in the BOM. Anyone have insights into this? My other VP28 (version B.1) has the correct value (120uf).

Due to Nichicon discontinuing many caps the 120µF/50V has been changed to a 100µF/63V part. I need to update many BOM's to reflect this.