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

[jeid]

Just wanted to thank Jeff for providing such a great product. Got my pair of VP26's yesterday and I put one together then and another one together today (with a hangover, so it shows how simple it is to do!)

I got the Gar2520 kits as well and they were a bit easier than I expected. A little fiddly but both great.

Chunger's guide was so helpful, the only thing missing from it was the LED install, but I managed to figure that out myself. I'll be looking to get a couple more in the next couple of months I suspect.

 

[epresalex]

Hey guys and Jeff,
Was all excited to get my vp26 built up and running the other day once I finally got the free time, made sure to read through the addendum as suggested and was following 'chungs  incredible documentation quite attentitively, when I got a little cocky (and perhaps overly buzzed) and made the wonderful mistake of soldering the t-pad pretty much flat to the board...

Can't say I know what I was thinkin, lined both pots up to the L bracket before hand and believed I knew what I was doing but for whatever reason didn't flatten the pcb front end with the side of the L bracket/ front end screws and nuts. So I've been trying to think of a clever way to inch the tpad from the board without ruining everything, but there are so many legs on the thing it seems pretty impossible. Just wondering if anyone might have any miraculous ideas before I just snip and desolder all the leads and order a new $30 attenuator.

Thanks guys,

-E

 

[jsteiger]

Desoldering the t-pad is the only choice you have. The cheapo desoldering pumps from Rat Shack are not great but should get this done and save you from buying a new t-pad. Otherwise invest in a Hakko desoldering tool and have some fun. They are awesome and if you do a lot of DIY it will be a great tool.

 

[epresalex]

Used a slightly better quality sucker from work with a little bit of added patience and was able to get it free enough from the pads to align pretty well. And according to my meter it still works!!! Doesn't look quite as nice as I'd like on the board (flux city) but after taking some alcohol to it it should be a bit more presentable. Thanks for the vote of confidence Jeff, I guess I just got a little over frustrated.

 

[Flukes]

Hi guys,

Just finished building a pair of VP26's and I'm having an issue with noise. Let me add that I am most certainly  new to DIY electronics (first build) and pro audio.

Is this normal? Could it be a grounding issue?

I've tried to attach an mp3 sample of the noise but the file format isn't accepted? Anyway around it? Clearly also new to forums!

Chung thanks for the guide and fun build Jeff!

 

[Flukes]

Hey fellas,

Giving this a cheeky bump.

Here is the noise sample. Dropbox Link [https://www.dropbox.com/s/v5zcgkd2p6r9x1p/VP26%20%281%29%20Noise.mp3?dl=0]

Any help tracking this bad boy down would be much appreciated.

Thanks!

 

[Flukes]

Some additional info.

a) I have made two of these pre's both of which are making the same noise.
b) Both are fitted with pre assembled GAR2520 DOA's bought from Jeff.
c) I have ruled out the following:
- Rack slot
- Cabling
- MR816X audio interface (noise still apparent when VP output goes direct to Monitor ins)
- Mic (noise still apparent with SM57 and Rode NT1A)

Notes:
- The MR816X pre's do not make the same noise
- I placed all transformers away from the mic cable and Lindell 10 cable but this does not diminish the noise
- During testing the amount of noise increases as the preamp gain and output attenuator increase
- The audio sample was achieved by Rode NT1 > VP26 > Interface. The phantom power was not engaged on the NT1A and both VP26 knobs were fully cranked.

Let me know if you have any ideas!

 

[jsteiger]

Well, seeing as how you have 2 pre's that are both behaving the same exact way, I would look at an outside cause. Under normal gain conditions, the pre's are very quiet. If you crank the input gain wide open, there will be some noise. Is there unacceptable noise at normal operating conditions?

I am not a DAW guy but have heard reports from a few customers with similar issues and then later report back that it was some setting on their convertor or something.

 

[burglar]

Hi Folks,

I built my VP26's about 2 months ago.  I only had a chance to test that they passed audio quickly and last night got my first opportunity to do some tracking.

On power up I noticed the attached noise.  This is high enough in the noise floor to be a problem.  It is present in both pre's though one a little brighter than the other.  It sounds like oscillating.

I'm using a Lindell 510, I don't have any other 500 series modules to test. however, when I heard the noise I pulled the leads and plugged them into two other pre's and the noise was gone so I have narrowed it down to the pre's or the lunchbox.

Have you guys any thoughts?

Channel 1 - https://soundcloud.com/sdosuk/noise-1

Channel 2 - https://soundcloud.com/sdosuk/noise-2
 

 

[Flukes]

Hi Burglar,

I'm having the exact same issue (see above). I'm using a Lindell 10 Slot for power and the noise I'm getting sounds very close to channel 1.

I'm going to try one of the VP26's today in a different power supply. I'll let you know how it goes!

 

[burglar]

Folker,

Very intrigued to hear your findings!

B

 

[Flukes]

Hey burgler, didn't end up happening today. When it does I'll let you know!

 

[burglar]

Flukes (sorry about previous typo)

Do you have any other 500 modules to test?  I wonder if it's a bad batch of 510's?

Anyone else have any thoughts on the noise?  Today I have tried one module @ a time, straight into a monitor speaker, both pre's exhibit exactly the same noise. 

 

[Flukes]

Not to worry mate.

No I don't have any other units to try it out with.

I have run the same test as you (VP's straight into monitors) with identical results, leading me to think that perhaps it's not the 510 anyway?

 

[burglar]

I live near Absulote music where I bought it,  I'm heading in on Saturday with said lunchbox & pre's.  I'm going to try some other modules in my lunchbox & also try my vp26's in some other lunch boxes, hopefully this will expose the root of the problem

 

[Flukes]

Let me know how you go burglar!

 

[chuckj]

I recently built a pair of VP26s with the SL2520 Red Dots and stepped gain. They seem to function fine and sound really good and they both pass clean sine waves until the gain is pushed, no level jump with the phase switches etc. However one is about 6-7 dB louder than the other at the same gain and attenuation setting. This discrepancy is fairly consistent with most any gain stage variation.

Any ideas? I can compensate by running test tones and checking meters in my DAW, but it would be nice to be able to use these quickly as a pair without the extra calibration step.
Thanks!
chuck

 

[burglar]

Let me know how you go burglar!

Unfortunately can't make it there this weekend, have you had any joy your end?

 

[Flukes]

Dang I might be able to try the VP's in a workhorse on Wednesday.

Will let you know. Did you get your LED's working?

 

[burglar]

Yeah, rookie move, wrong polarity, hasn't helped the noise any though