Peavey tube compressor trafo upgrade help

[pucho812]

o.k. so I have a peavey amr vc/l-2 tube compressor. I like the sound but feel changing the input and output trafo's would make it sound much better.
Unfortunately the trafo's are not marked and on the schemo there are no values wrtten for the trafo's.

here is a link to the schemo
http://www.zmix.net/pub/VC-L2 Schematic.pdf

I would imagine it's a 1:1 input and 1:1 output trafo. I am looking for A nice replacement. so my question is
1. what would be the easiest way to get the trafo values?
once I get that I can swap it out pretty easily(SP) I think..

 

[ToobieSnack]

I'd like to hear one of these compressors.
How do you like it?
pros/cons
info much appreciated
thanks
TS

 

[pucho812]

much about that was discussed here. It's made by a peavey side company that was their attempt at pro studio gear.
Link of info
http://www.amptone.com/peaveyvcl2.htm

Groupdiy discussion about it
http://www.groupdiy.com/index.php?topic=4973&highlight=peavey

IMO it sounds good nice and old skool comp sounds and has a limiter switch plus it is duel mono. It was their attempt at a LA-2a style opto comp. It's said to be complete all tube with no solid state electronics I.E. a tube make up stage. real good for the money. usually you can find them pretty cheap because it still has peavy in big letters. But all in all great for the price and pretty good over all. I mainly want to replace the trafo to see if I can make it even better and since trafos add to the sound...
I got their tube mic pre that AMR did and first thing I did was remove the peavy logo... no one know and I have had guys prefer it over my GT vipre. IMO it's good but not that good of a mic pre. again good price used cause it says peavey...

 

[NewYorkDave]

Measure the turns ratio, primary inductance, etc. of the transformers and take it from there. Search this board and you'll find loads of discussions on transformer measurements. One measurement is worth a hundred guesses.

 

[pucho812]

I havn''t measured it yet but I got two leads in and two leads out so far all signs indicate 1:1 trafo.... there are markings on it ...

(Top)
70500348
EIA 682 0016

(One Side)
DB-348

(One side)
Insp 96

hmmmm EIA a company making trafo's that I havn't heard of?

 

[pucho812]

I have started to find some info on my trafo's

according to
http://www.triodeel.com/eiacode.htm#xfmr

the code 682 indicates a company called "electrical windings"

 

[pucho812]

here is a thought what would happen if I were to bypass the transformer?

 

[pucho812]

pumb?

 

[DrFrankencopter]

Is there no unbalanced output already? I have a Peavey VMP-2 (same series as the VCL) and there is an unbalanced output on that. Actually, the unbalanced out sounds much better than the transformer out. I think that peavey's output stage has a hard time driving the transformer output (plus whatever load you might attach....with low impedances being particularly bad).

For the input, I'm not sure what they would use, but knowing the way peavey works its probably the same as the output xfmr. Maybe best to replace it with a 10k:10k line input transformer (lundahl perhaps).

Or, try bypassing the transformer altogether....sometimes the best transformer is no transformer.

Cheers,

Kris

 

[pucho812]

Or, try bypassing the transformer altogether....sometimes the best transformer is no transformer.

Was my second choice....

First thought it is a 1:1 turns 10k:10K input transformer and a standard 4:1 output 10K:600 output.... hmmmmmm[/code]

 

[clintrubber]

FWIW, while looking for VMP-2 info i found some about the VC/L-2:

from http://forums.peavey.com:8080/~AMR/guests etc):

Topic: VC/L-2 comp information (1 of 2), Read 12 times
Conf: Signal Processors
From: pucho812 [email protected]
Date: Thursday, March 31, 2005 01:56 AM

Hi guys.I'm Looking for information on the input/output transformers. Make,model,windings,etc,etc,etc. I have a schematic of VC/L-2 but does show that information just a transformer. I am guessing the input is a standard turns ratio of 1:1 and the output a turns ratio of 4:1?
Plus I am in search of a manual of said compressor?









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Topic: VC/L-2 comp information (2 of 2), Read 11 times, 1 File Attachment
Conf: Signal Processors
From: Aubrey [email protected]
Date: Thursday, March 31, 2005 09:48 AM

Line input transformer (70511562)
DESCRIPTION: Line Input Transformer

IMPEDANCE RATIO: 10K ohms to 10K ohms
PRIMARY SOURCE INDEDANCE: 600 ohms or less
TURNS RATIO: 1:1
20Hz MAX INPUT LEVEL: +16 dBu
BANDWIDTH (-3db point): 85kHz
MAGNETIC SHIELD: 60db Case with Sperate Lead
FARADAY SHIELD: 1 with Sperate Lead
RECOMMENDED LOAD: 10K ohms
RECOMMENDED RC NETWORK: Use 30K+270pf
PRIMARY DCR: 2.1K ohms
SECONDARY DCR: 2.1K ohms
MAGNETIC SHIELD: 60db Case with Sperate Lead
FARADAY SHIELD: 1 with Sperate Lead
RECOMMENDED LOAD: 10K ohms
RECOMMENDED RC NETWORK: Use 30K+270pf
PRIMARY DCR: 2.1K ohms
SECONDARY DCR: 2.1K ohms



Out put transformer
BE-338-A-X VMP-2 OUTPUT TRANSFORMER

30K:600 ohms, 70.7VRMS:10VRMS, 3267T:463T


Power transformer
BE-28741 Domestic Power Transformer
Used one per, VMP-2 domestic unit
458VDC no load, 397VDC full load, 47 uf
35.8VDC no load, 24.5VDC full load, 4700 uf
Aubrey Fulton


VCL 2 MANUAL.PDF (818KB)

regards,

Peter

 

[clintrubber]

Oops, that was you asking around over there - well, looks like your question has been answered ! :wink:

 

[Christian]

The transformers in the VMP-2 Pre are Reichenbach's. Same era, could be the same.

 

[pstamler]

[quote author="DrFrankencopter"]Is there no unbalanced output already? I have a Peavey VMP-2 (same series as the VCL) and there is an unbalanced output on that. Actually, the unbalanced out sounds much better than the transformer out. I think that peavey's output stage has a hard time driving the transformer output (plus whatever load you might attach....with low impedances being particularly bad).[/quote]

That's what I found when I reviewed the VMP-2: excellent performance into unbalanced 10k load without using the transformer out, crummy performance into a 10k load using the balanced out (high distortion with an ugly spectrum) and awful performance into a 600-ohm load. If I had to guess, I'd say the compressor uses the same circuit or a similar one, and I'd bypass the xformer for best results.

Peace,
Paul

 

[pucho812]

NO fair I never got an e-mail saying there was a reply. I gave up. cool now though :twisted:

 

[clintrubber]

NO fair I never got an e-mail saying there was a reply. I gave up. cool now though

Cool, nice it's kind of solved.

Hope they can provide alike info for the VMP-2 at that peavey-forum - would like to have alook at the VMP-2 manual and schematic.
Let's see what they come up with... or if anyone here has this info already, please tell ... (I have already seen the TMP-1 schematic though).

regards,

Peter

 

[clintrubber]

It seems that both the VC/L-2 and VMP-2 are using an alike or even identical output-section:
strapped 12AT7-sections and the same output-TX.

The VMP-2 is reported to have problems there - one is advised to use
the unbalanced out (as already in the PStamler-review).

So one would expect the same thing for the VC/L-2 balanced-out, but is it
in practice a problem there ?


If so, how could it be tackled ? It feels funny to use a TX-coupled tube-pre
but having to skip the eventual color of the output-TX because of a 'design-imperfection'... :roll:


BTW, Peavey-support has just kindly added VMP-2 info now as well:
http://forums.peavey.com:8080/~AMR/guests (then sign.proc & vmp-2)

Regards,

Peter

 

[zmix]

I've done some extensive testing and subsequent modification to my newly acquired VC/L-2 and I will state that the transformers are NOT the problem. The output driver is a single ended, class A parallel design, and it simply lacks the power of a more conventional output design, especially in the low end.

 

[mutetourettes]

eleven year thread necro.. but Hey..

Zmix - can you shed any light on what you eventually did to beef up the output stage's power?

guitar-amp-based-hocus-pocus ahead:
would chucking in a 12BH7a or ecc99  work? - seems to be what guitar folk do..
or even:
http://www.diyaudio.com/forums/tubes-valves/211582-12ax7-12at7-recommendations-4.html#post3003424
a late production mullard cv4024 (military spec 12at7) which is may have better bass, not as 'thin sounding' as normal 12at7...

 

[JohnRoberts]

eleven year thread necro.. but Hey..

;D this thread was before my time here..

Zmix - can you shed any light on what you eventually did to beef up the output stage's power?

guitar-amp-based-hocus-pocus ahead:
would chucking in a 12BH7a or ecc99  work? - seems to be what guitar folk do..
or even:
http://www.diyaudio.com/forums/tubes-valves/211582-12ax7-12at7-recommendations-4.html#post3003424
a late production mullard cv4024 (military spec 12at7) which is may have better bass, not as 'thin sounding' as normal 12at7...

I am reluctant to expect some easy tube swap upgrade to improve anything. If the output stage is challenged by 600 ohm termination maybe don't run it into 600 Ohms.

There are other more recent threads around this forum discussing these products.

FWIW adding the high Z unbalanced output to the VMP was my idea, I am not a fan of distortion.

JR

PS:  I am still not a tube guy... but I influenced feature set and approach on these (I was the top AMR guy at Peavey while the tube design work was done by other Peavey engineers).