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Ampeg V4 Club

#961
Just noticed a new development with my V4B! Vintage 70s with a recent trip to the doctor for some power supply repairs.

During the fretted/open D, and sometimes the C# the amp will produce an unpleasant crackling harmonic. This noise does not interrupt any fundamental of the notes, its just a nasty extra. With a little research, the corresponding frequency for the notes in question are 69.3hz (C#) and 73.2hz (D). Something around this 70hz frequency is perhaps the culprit, but the noise in question sounds like a high-pitched fuzzy crackle. The issue is not apparent at any other octave of these notes.

In attempts to isolate the issue I tried the following:
switching speaker cables,
guitar cables,
bypassing the pedals,

I have also used a backup amplifier to test the speaker cabinet being used with the V4B. No issues with the cabinet.

Its going to see the doctor again, but if anyone has any thoughts or perhaps a similar issue in the past, i'd love to give the tech a heading to find the issue!

Cheers!
 
#962
jbd5015 said:
During the fretted/open D, and sometimes the C# the amp will produce an unpleasant crackling harmonic. This noise does not interrupt any fundamental of the notes, its just a nasty extra. With a little research, the corresponding frequency for the notes in question are 69.3hz (C#) and 73.2hz (D). Something around this 70hz frequency is perhaps the culprit, but the noise in question sounds like a high-pitched fuzzy crackle. The issue is not apparent at any other octave of these notes.

Cheers!
Click to expand...

Wiggle the output tubes in their sockets.
 
#964
jbd5015 said:
Just noticed a new development with my V4B! Vintage 70s with a recent trip to the doctor for some power supply repairs.

During the fretted/open D, and sometimes the C# the amp will produce an unpleasant crackling harmonic. This noise does not interrupt any fundamental of the notes, its just a nasty extra. With a little research, the corresponding frequency for the notes in question are 69.3hz (C#) and 73.2hz (D). Something around this 70hz frequency is perhaps the culprit, but the noise in question sounds like a high-pitched fuzzy crackle. The issue is not apparent at any other octave of these notes.

In attempts to isolate the issue I tried the following:
switching speaker cables,
guitar cables,
bypassing the pedals,

I have also used a backup amplifier to test the speaker cabinet being used with the V4B. No issues with the cabinet.

Its going to see the doctor again, but if anyone has any thoughts or perhaps a similar issue in the past, i'd love to give the tech a heading to find the issue!

Cheers!
Click to expand...

The source of the problem could be electronic or mechanical.

When it just occurs at one frequency, the first thing that I think of is that it is a resonance. Try damping the tubes by pressing on one at a time with an oven mitt. Also try applying pressure to other places on the chassis and on the cabinet (front and back panels, strap, etc.) to help you to determine if it is a vibration. Something could be loose and mechanical vibrations can be converted to electronic. Or the noise could be just electronic. A bad component or even a solder joint can do this.

A good possibility is a microphonic tube. Make sure that all the tubes are seated properly in their sockets. If they wiggle in and out of the socket too easily, the socket contacts may need re-tensioning.
 
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#965
I have ordered all of the supplies required to refurbish my VT-22, build a head box for it, and to build a matching speaker cabinet (going with a 2x15 with Faital 15PR400's).

All of the little things really add up fast... NOS tubes aren't cheap either (got NOS for all of the preamp tubes except the 12AX7's).

I'm getting pretty eager to get this thing built!
 
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#967
beans-on-toast said:
Oh man, you can say that again. Sometimes I put so much into an amp that I could never get back what I put into it. Good reason for never selling it.
Click to expand...
I restored a 1969 Fender Twin Reverb last year. I did a complete electronic and cosmetic overhaul. By the time I was done, it was in better shape than when it left the factory.
I eventually decided to sell it and when I did, I tallied up everything I put into it... As it turns out, what I thought was a pretty decent profit worked out to paying myself about $1.50 an hour for the restoration...
 
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#971
If I show a picture of my V4b in my studio being used and enjoyed by the likes of this lot do I get a number.
image.jpeg

image.jpeg

Anybody want to have a guess at who the guitarist is sitting on the left and what's the name of the band he is in here.:-)
 
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#973
LOL, last time i start 'wiggling' tubes.

I wiggled all the tubes, amp off. No change to the sound.

I had the amp running, and gave each tube a little nudge. The 6K11 tube is definitely an issue. I got some crazy crack noise, then the amp went quiet.

It has VERY limited output now. I suppose it'll make the hunt a little easier for the tech when I drop it off tomorrow!
 
#974
vmabus said:
The deadly V-2/V-4 combination:
View attachment 731125 View attachment 731126
This was my brother's guitar rig for 30-some years, after he bought it from a bass player in a former band. He mostly used it with the V-2 cabinet. He had a tech add the master volume, and did no other service to it.
The fundamental sound is pretty good, but there seems to be a lot of distortion, and the speakers fart out pretty easily. Tolex is rough on one side, showing evidence of dragging (over concrete?).
I need to clean the pots and dust everything; any suggestions for anything else I can do while it's apart?
Click to expand...
The tubeset from Fliptops came today; I dusted the inside, cleaned the controls, inspected.
The old tubes all say Magnavox, so I guess they're 43-years-old...
There was no evidence of leaking caps, no cold or broken connections, so I hope for happy outcomes :hyper:
I'll let it sit over night to make sure all the De-Oxit has evaporated; more news tomorrow!
 
#975
vmabus said:
The tubeset from Fliptops came today; I dusted the inside, cleaned the controls, inspected.
The old tubes all say Magnavox, so I guess they're 43-years-old...
There was no evidence of leaking caps, no cold or broken connections, so I hope for happy outcomes :hyper:
I'll let it sit over night to make sure all the De-Oxit has evaporated; more news tomorrow!
Click to expand...
In a word: Glorious!
Full and rich for guitar; deep and biting at the same time for bass! And, tremendously loud for 60 watts!
And quiet!
 
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#976
This thread is killing me. I want an old 70s V4B so bad yet I have absolutely no need for one. I have never heard an amp I liked the tone of more. I had 2 in the past and the second one still had original Magnaxov tubes in it and was in excellent condition. Sold it like a fool. It's one of the only things I regret selling of all the bass gear I have gone though. :crying:

Nice amps everyone!!
 
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#978
metron said:
This thread is killing me. I want an old 70s V4B so bad yet I have absolutely no need for one. I have never heard an amp I liked the tone of more. I had 2 in the past and the second one still had original Magnaxov tubes in it and was in excellent condition. Sold it like a fool. It's one of the only things I regret selling of all the bass gear I have gone though. :crying:

Nice amps everyone!!
Click to expand...
Just get a new one. It's 20 lbs lighter and sounds the same :D
 
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#979
JimmyM said:
Just get a new one. It's 20 lbs lighter and sounds the same :D
Click to expand...

You'll have to pardon my ignorance as I haven't kept up with the conversation on the new one and I'm sure it's been discussed at length but... does it really sound the same? That gooey syrupy 3D bass tone, the edgy fur as breakup starts, and the rip-your-face-off full on grind at higher volumes? :D
 
#980
metron said:
You'll have to pardon my ignorance as I haven't kept up with the conversation on the new one and I'm sure it's been discussed at length but... does it really sound the same? That gooey syrupy 3D bass tone, the edgy fur as breakup starts, and the rip-your-face-off full on grind at higher volumes? :D
Click to expand...

They are different amps, the circuits are not the same. BUT, the reissue is designed to sound like the vintage V4B. They based it on a choice 1974 model.

If you like the SVT CL preamp, that's more or less what you get with the V4BR. The reissue's transformers are not as heavy duty. Different tubes are used.

The advantage of the reissue is that it doesn't have the issues that come with a vintage amp. Some vintage amps need a lot of work to bring them up to spec.

People love the reissue.
 
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