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#1 2008-12-05 05:37:48

drzontar
Member
From: Rochester, NY
Registered: 2008-11-11
Posts: 33
Website

V4 Repair in Upstate NY

I found out that the V4 I bought recently was serviced a couple of years ago by:

Sound Source
161 Norris Dr.
Rochester, NY 14610-2422
(585) 271-5370

I deal with these guys on a regular basis. All the staff are great. And Rob (the repair guy) is very knowledgeable.

I'd also like to mention John Nau:

Nau Engineering
7 Mapleton Dr.
N. Chili, NY 14514
naueng@frontiernet.net
585-594-8129

John builds custom tube amps, and can fix or modify just about anything.


"Trust no one, least of all yourself." - Michael O'Donoghue

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#2 2008-12-09 12:03:25

rob
Member
Registered: 2008-10-28
Posts: 171

Re: V4 Repair in Upstate NY

Hi, I am on Long Island. I do repairs, build amps and cabinets also.

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#3 2014-02-14 15:41:21

doug_olitsky
Member
From: Gold Coast, Long Island, NY
Registered: 2009-02-19
Posts: 45
Website

Re: V4 Repair in Upstate NY

Rob

Where on LI are you.

I'm Sea Cliff, near Glen Cove

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#4 2016-02-25 08:34:46

Ampig
Member
Registered: 2009-04-03
Posts: 12

Re: V4 Repair in Upstate NY

I have a small repair business here in my home in the Finger Lakes region outside of Ithaca, Ny.  I have several V4's and work on them as an act of passion.  I play through a master volume model and can't get enough of it. I love these old Ampegs and I want to keep them going.  If it's broken, I can fix it.
You can reach me at sseidts at yahoo dot com.

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#5 2018-02-28 10:21:10

Tony
New member
Registered: 2018-02-27
Posts: 8

Re: V4 Repair in Upstate NY

Hope someone can help me. I live in northern BC and there are no Ampeg repair shops anywhere near my city. I have converted the VT-22 V4 to EL34's on two circuits. I am using only two EL34's now (one on each transformer side. I have added the 1k ohm 10 watt grid screen resistors. (I will change them to 5 watt resistors when they arrive), set bias at 29ma each tube.

My question is... when I watch the bias current meters, (a seperate meter monitoring plate current on each of the two tubes) both on idle at 29ma each (545vdc), when playing at low to medium volume, bias seems fine (current fluctuates properly). But when I play loud, (more volume) the bias currents become unbalanced.

Watching both meters, one will fluctuate between 29 to about 95ma while the other fluctuates from 29 past 200ma. I have swapped and changed tubes of different manufacturers and it is definitely the same side of the transformer and not the tubes themselves. I had verified the meters also. I have checked the component values and all are fine, within <5% values.

Then, when I convert back to the 7027A's, re-adjusting the bias (using the other un-modded two tube circuits)the grid currents on both tubes are equal, both reaching together from 29ma to 95ma.

It does not matter which "balanced" EL34's I use, the same side of the transformer current value always excede the other by at least double.

I am using the appropriate speaker output impedance. Two tubes, 4 ohm switch setting for 8 ohm speaker load.

Anyone know what is going on?

Best regards,
Tony

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