jmcnul

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #60 on: October 26, 2012, 03:12:16 AM »
Well, I tried a beta 52 on kick and got solid blocks in protools. I'm out of my lunchbox, line into my 002. It just seems like something's not right. I got my input and output as far down as they can go and am still clipping. This is with mic engaged though, when in line mode it seems alright. Thanks


jsteiger

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #61 on: October 27, 2012, 12:17:58 PM »
It is easier and more accurate to judge with test tones and something to measure the output level. The line is easy enough since we can test for unity gain. If the line setting is at unity, the mic setting should be right. The only difference is the pad for line input.
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jmcnul

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #62 on: October 30, 2012, 12:46:56 AM »
I am pretty sure something is not right though. What could potentially be the cause?

kante1603

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #63 on: October 30, 2012, 03:00:31 AM »
I am pretty sure something is not right though. What could potentially be the cause?
It is impossible to say when you write that "something is not right".
Let's start with the unity gain test as Jeff recommends.
Apply a sine wave,say with a 1 k frequency at  a known level,say 0dBu (=0,775 v or 775 mv) to the mic pre input.
Set the gain to "line".
Set output level to middle position ( to zero position so there is no boost or attenuation).
Filters to off for now.
The reading at the output should be the same as the input now,at least very very close to it.
You can measure with a level meter or a dmm set to ac.
If you measure with a daw be aware of the specs of your interface,you should know what level your dBfs refers to.
If you measure with a dmm then do it between pins 2 & 3 (hot and cold signal).
This is for checking the pre itself,so nothing else should be connected except of the signal generator on input and a meter of some kind on output.

Good luck,

Udo.

okgb

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #64 on: November 01, 2012, 04:56:07 PM »
Just built up a pair , just with a quick voice test [ my own  ] they seem to have a nice " size " & openess
the HPF  " feels smooth too , nice to have options with that , who needs ultra low end on vocals ?

One question , I'm assuming the opamps closer to their respective transformers are the in and output stages ?
built the units with Gar 2520 & 1731  so used the 1731 for input [ at the bottom of the card ? ] and the 2520
closer to the out xfmrs .

thanks & regards Greg
GKB Audio / Greg Boboski

jsteiger

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #65 on: November 01, 2012, 06:41:07 PM »
Awesome Greg 8)

A1 is the preamp opamp and A3 is the post fader booster amp. For the folks using the gar opamps, most seem to prefer the gar2520 in the preamp position and the gar1731 in the post fader booster position. To each, his own though. I often tell folks who ask me about what to use where, there really are no wrong choices. Experiment and see what works best for you.
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CAPI is not affiliated with, endorsed by, or sponsored by API.

okgb

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #66 on: November 01, 2012, 10:50:56 PM »
Quote
Well, I tried a beta 52 on kick and got solid blocks in protools. I'm out of my lunchbox, line into my 002. It just seems like something's not right. I got my input and output as far down as they can go and am still clipping. This is with mic engaged though, when in line mode it seems alright. Thanks

Don't want to avoid the obvious but you are going into a Line input on the 002 correct ?
channels 5-8 are line with no mic [ gain  ] input options
GKB Audio / Greg Boboski

kante1603

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #67 on: November 02, 2012, 02:42:51 AM »
Don't want to avoid the obvious but you are going into a Line input on the 002 correct ?
channels 5-8 are line with no mic [ gain  ] input options
Hello,

good point,one never knows......
Oh,I forgot to mention to look at the specs of the dmm if using this for measuring too because some of the cheaper ones won't "see" a 1khz sine wave.You must choose a lower frequency from your signal generator then!


..and @Greg:Congrats for your pres of course!Nice guys,no?I love mine,I have two gar2520 in them.
Cheers,

Udo.

jmcnul

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #68 on: November 12, 2012, 08:17:55 PM »
So, I switched inputs around and actually finished the pre (added green LED and IEC to power signal indicator) and that seemed to do the trick. Built another 28 and they both sound fantastic. Couldn't be happier except for the fact that I want more haha. I think the next purchase will be the 51x rack

kante1603

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #69 on: November 13, 2012, 01:35:04 AM »
So, I switched inputs around and actually finished the pre (added green LED and IEC to power signal indicator) and that seemed to do the trick.
:o
Sorry,but I don't get it.
What was the solution to your issue?
Udo.


jmcnul

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #70 on: November 13, 2012, 03:00:31 AM »
Haha, I'm not quite sure either. Could be a variety of things, but at this point I'm happy with a rocking pre

kante1603

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #71 on: November 13, 2012, 04:28:51 AM »
O.K.

tonycamp

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #72 on: November 14, 2012, 12:02:32 AM »
Momentary hijack questions, then i'm gone :) i've been thinking about selling my brand new seventh circle audio rig, i built 2 api style a-12s and 2 neve style n72's, with the new black chassis. I'm loving the a12's with the red dots, but i'm bummed i can't drive the input hard and attenuate the output , (pads are a drag) I found the capi stuff and I'm thinking i'm wanting the capi vp28's.
my questions are as follows;

1. Are they that much better sounding than the a12 with scott lieber red dots?
2. does the channel fader nob on the vp28 allow you to drive the input hard and cut the output enough to not overload your daw input?
3. would it be worth it to build a variable attenuator for the output of my a12 and forget the vp28 and 51x?
4. any other reasons i'm not aware of that make the 51x and vp28's a better option in the long run?

Thanx for your input fellas,
T

Dylan W

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #73 on: November 14, 2012, 01:34:28 AM »
Momentary hijack questions, then i'm gone :) i've been thinking about selling my brand new seventh circle audio rig, i built 2 api style a-12s and 2 neve style n72's, with the new black chassis. I'm loving the a12's with the red dots, but i'm bummed i can't drive the input hard and attenuate the output , (pads are a drag) I found the capi stuff and I'm thinking i'm wanting the capi vp28's.
my questions are as follows;

1. Are they that much better sounding than the a12 with scott lieber red dots?
2. does the channel fader nob on the vp28 allow you to drive the input hard and cut the output enough to not overload your daw input?
3. would it be worth it to build a variable attenuator for the output of my a12 and forget the vp28 and 51x?
4. any other reasons i'm not aware of that make the 51x and vp28's a better option in the long run?

Thanx for your input fellas,
T

I don't have the SCAs so I can only speak to #2. The channel fader on my VP28s is very useful for hitting the input hard and pulling back so you don't clip your interface. It's also got a pad (-20db, I think?) and a padded line input. They do sound noticeably thicker than API 512s I've used and are perhaps more useful on sources where the 512s would be often be too forward or "pokey," eg vocals. They don't seem to sit quite as far in front of the speakers as the 512--it's like they're pulled back a little bit in space, with a little more room around the sound. Not sure if that description makes sense. Mine have a gar2520 on the input and a gar1731 on the fader, btw.

They're also great for using on the 2 bus, either in line level mode or as makeup gain for passive summing. That versatility and the ability to throw them in line input on a kick or snare in the mix, for example, made them attractive and useful to me.

Dylan

kante1603

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #74 on: November 14, 2012, 02:11:46 AM »
Hello T.,

I love mine because they're really versatile.
You can get tons of different sounds pretty easy.
They have an isp led which is a good little helper in racks located a bit off your workspace.
One super feature is the excellent hpf with 3 corner frequencies and switchable slope at 6 or 12 dB.
This will help you on tracking without the use of an additional eq.
In line mode it is a perfect tool to bring back some life to those boring digital sounds.

Hope to have helped,

Udo.

P.S.:I have gar2520's in both postions.

okgb

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #75 on: November 14, 2012, 09:43:26 AM »
  Yeah , it's a good HPF  , Wish every pre had one

Don't overlook running multi stage pres with the outputs fully up or one notch away from top
and adjusting the in gain to where you like it , depending on where the control for the output stage is
you can get it working harder ,  keeping the output waay down can be like closing the door so you're not letting
much input gain through no matter where you have it set .  [ unless the attenuator is after the output transformer ,
then by all means run it low ]  ..............o.k. varied results on that depending on pre , so as always just listen !
« Last Edit: December 02, 2012, 10:45:24 AM by okgb »
GKB Audio / Greg Boboski

tonycamp

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #76 on: November 14, 2012, 03:37:50 PM »
Nice, the best info always comes from u guys at GDIY! thnx fellas, I'm now on the waiting list for 52x 500 and 4-vp28's ;D, now i have to figure out a worthy DIY 500 series replacement for my N72 neve style pre's :-\

okgb

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #77 on: November 14, 2012, 08:29:12 PM »
Soundskulpter has an everything included  mp573 , I've personally build a couple of those
they sound great , Onlyme had a minimal kit on the white market i believe , both d.i.y.
maybe more check the W.M.
Oops I should have just pm'd ya instead of clogging up the VP 28 thread
classic api also one stop shopping with great support [ clear instructions & details ]
« Last Edit: November 14, 2012, 09:35:17 PM by okgb »
GKB Audio / Greg Boboski

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #78 on: December 02, 2012, 12:42:19 AM »
This build was a lot of fun!

Chunger your guide was ridiculously amazing and helpful.

One question: one thing I really liked about the VP26 guide was the testing procedure at the end. Is there a similar voltage checklist for the VP28? I couldn't seem to find one anywhere.

jsteiger

Re: [BUILD] VP28~500 Series~2-Stage Preamp~Official Support Thread
« Reply #79 on: December 02, 2012, 09:55:52 AM »
I don't have any specific tests posted for this build but the main voltage measurements will be the same for any of the modules. Just make sure you have your +/-16V readings at the appropriate sockets.
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CAPI is not affiliated with, endorsed by, or sponsored by API.


 

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