Pulling Pre-Amp Tubes

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Pulling Pre-Amp Tubes

Postby BigNath on Thu May 18, 2017 1:01 am

Hi all,

new to the forum, and I posted a new topic the other day and it hasn't shown up yet...not sure if it needs to be approved by admin, or if I did something wrong with submitting it...not sure...

Anyways, I have acquired a Silver Face Vibrosonic Reverb (basically a Twin Reverb with a 15" instead of 2 x 12's)...
And with all of the pre amp tubes, it's a bit noisier than I would like. I THINK I have it narrowed down to the reverb circuit, as pulling V2-5 and leaving V1 and V6 results in a much more useable noise floor.
Leaving them all in apart from V3 and 4 (reverb driver and recovery) seems to keep it nice and quiet and gives me both channels just without reverb. I have a reverb pedal that I prefer so sonically this is fine with me.

My question is: in the meantime until I can get it properly gone over again by my local tech, can I safely run this amp with all tubes installed except V3 and 4?
If this was safe, i'd happily use the amp like this long term, although I would eventually like to get to the bottom of it...

The amp has had a recent service/restoration which included:
All new tubes - all of them. and biased.
the caps replaced
pots cleaned and checked
grounds checked
new Celestion Fullback speaker fitted.

Any thoughts on what the issue could be would be great. Any opinions on how safe it would be to run the amp with V3 and 4 pulled would be also appreciated.
Cheers,
BN
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Re: Pulling Pre-Amp Tubes

Postby Factory Guy on Tue May 23, 2017 8:33 pm

The reverb driver & return tubes can be pulled and free up current to the other tubes. The amp should "sound" better. You can leave out the preamp tube on the channel you aren't using also to fee up more current as well.

If the amp has had a recent service and restoration by a tech I would not take the amp back to that guy if the reverb is not lush and usable. That should have been corrected the 1st time if he LISTENED to the amp when he did his final test... Just sayin'.
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Re: Pulling Pre-Amp Tubes

Postby stratele52 on Tue May 23, 2017 8:48 pm

Factory Guy wrote:
If the amp has had a recent service and restoration by a tech I would not take the amp back to that guy if the reverb is not lush and usable. That should have been corrected the 1st time if he LISTENED to the amp when he did his final test... Just sayin'.



+1000

What this guy do, any electronic beginner can, but to fix a amp, make it play nice you need a qualified tech.
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Re: Pulling Pre-Amp Tubes

Postby JJman on Tue May 23, 2017 11:43 pm

Pulling V1 or V2 will increase the idle current of the 2nd stage of the functioning channel. This is because those cathodes are sharing a resistor/cap. This is a "mod" that some say sounds good but I didn't notice a difference when I tried it a few times in my DR.
-If it says "Vintage" on it, it isn't.
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Re: Pulling Pre-Amp Tubes

Postby BigNath on Wed May 24, 2017 12:34 am

Awesome, thanks all for the replies! Just as long as i'm not going to damage my amp by playing with those pre-amp valves pulled, AT THE MOMENT that's all I really care about.

In the past few days the noise floor has diminished considerably. Makes me wonder if there was a small issue with some dirty valve sockets or something...We also have had a lot of works in our area with nbn rollout occurring in our block/street...Wondering if this has been also affecting the noise floor.

The noise certainly isn't loud enough to stop me from using it (once the master is above 2-3, and the preamp vol above 3-4 it's not noticeable).
The issue with the reverb is that i'm sure that's making what background noise is there, louder. The reverb actually sounds beautiful, and appears to work as it should....i'm just not typically a fan of spring reverb. Blasphemy I know..

Overall the issue with the backround noise seems to have corrected itself, whether that's by my constant pulling and re-installation of preamp valves or not I don't know, so i'll keep an eye on it for know and pull them out if the noise returns, or continues to be a problem. Then i'll get it gone over know that I think I have the area targeted...

My biggest drama at the moment is finding a nice 'rock' overdrive for it... It responds differently to my other amps (212 Hot Rod Deville, Silverface Bassman 10). getting nice results from either a tubescreamer or my MIJ OD1. My go to dirt box (typically a TC Electronics NovaDrive) doesn't sound as good in the Vibrosonic as it does in my Deville... The search continues :D

Cheers for everybody's help!

EDIT:
The tech I use is certified repair business for many music companies, and I have used him before to do work on my amps (my bassman for example) and have been very pleased with his work.
I'm wondering...I guess it's possible for the power throughout a house to be dirtier/cleaner than another building. Maybe I've just got dirty power coming through my house contributing (not necessarily causing) to the probem. Maybe that could explain why it left his bench with an apparent clean bill of health?
I have band rehearsal tonight so will take it for it's first run out of my house, and see how it goes...
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Re: Pulling Pre-Amp Tubes

Postby stratele52 on Wed May 24, 2017 10:26 am

The best is to ask to this guy what he is thinking about your reverb.
And yourself do more test
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Re: Pulling Pre-Amp Tubes

Postby JeffH on Wed May 24, 2017 10:47 am

Maybe try some electronics cleaner in the tube sockets.

Also, the reverb output and input jacks could be corroded - try some cleaner in there and on the RCA plugs on the cables. They can have some oxidation present. Even if you don't have cleaner, just try plugging/unplugging or rotating the plugs to break up a corroded connection.
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Re: Pulling Pre-Amp Tubes

Postby stratele52 on Wed May 24, 2017 11:27 am

JeffH wrote:Maybe try some electronics cleaner in the tube sockets.

Also, the reverb output and input jacks could be corroded - try some cleaner in there and on the RCA plugs on the cables. They can have some oxidation present. Even if you don't have cleaner, just try plugging/unplugging or rotating the plugs to break up a corroded connection.



+1

This was a basic clean up with a amp service
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Re: Pulling Pre-Amp Tubes

Postby pdf64 on Wed May 24, 2017 1:59 pm

Factory Guy wrote:The reverb driver & return tubes can be pulled and free up current to the other tubes. The amp should "sound" better. You can leave out the preamp tube on the channel you aren't using also to fee up more current as well...

I can't see how the vibrato channel could work following removal of the tube in V4 :think_1:
V4b being the last stage of that channel http://www.thevintagesound.com/ffg/vibr ... rb_sf.html
Tricky to pull V4a (reverb recovery) without V4b (mixer recovery) going too!
I think it must have been V3 (reverb driver) and V5 (trem oscillator/buffer) that were removed.

I don't think it's good practice to use lubricating cleaner spray in high voltage areas, eg tube pins / sockets; as the deposited grease may promote dust, solder splatter etc adhering to the area, potentially leading to arcing.
I've done it in the past (when they're de-energised!) and it's not caused a problem that I know of, but don't anymore.
So I suggest to use a deposit free spray cleaner, and if necessary, apply lube cleaner to a cloth and carefully wipe the pins afterwards, avoiding the tube / socket base.
My band:-http://www.youtube.com/user/RedwingBand
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Re: Pulling Pre-Amp Tubes

Postby Factory Guy on Wed May 24, 2017 8:31 pm

The poster noted he was using the NORMAL channel V1 so the removal of the tubes for the vibrato/reverb wouldn't be an issue in this case.

pdf64 wrote:
Factory Guy wrote:The reverb driver & return tubes can be pulled and free up current to the other tubes. The amp should "sound" better. You can leave out the preamp tube on the channel you aren't using also to fee up more current as well...

I can't see how the vibrato channel could work following removal of the tube in V4 :think_1:
V4b being the last stage of that channel http://www.thevintagesound.com/ffg/vibr ... rb_sf.html
Tricky to pull V4a (reverb recovery) without V4b (mixer recovery) going too!
I think it must have been V3 (reverb driver) and V5 (trem oscillator/buffer) that were removed.

I don't think it's good practice to use lubricating cleaner spray in high voltage areas, eg tube pins / sockets; as the deposited grease may promote dust, solder splatter etc adhering to the area, potentially leading to arcing.
I've done it in the past (when they're de-energised!) and it's not caused a problem that I know of, but don't anymore.
So I suggest to use a deposit free spray cleaner, and if necessary, apply lube cleaner to a cloth and carefully wipe the pins afterwards, avoiding the tube / socket base.
Sound Engineer/Guitar Strangler/Motorcyclist. Not neccessarily in that order... Depends on what day it is :)
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Re: Pulling Pre-Amp Tubes

Postby pdf64 on Thu May 25, 2017 7:21 am

BigNath wrote:...Leaving them all in apart from V3 and 4 (reverb driver and recovery) seems to keep it nice and quiet and gives me both channels just without reverb..

Factory Guy wrote:The poster noted he was using the NORMAL channel V1 so the removal of the tubes for the vibrato/reverb wouldn't be an issue in this case.

Hmm, to my reading, BigNath seems to say that both channels are operating?
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Re: Pulling Pre-Amp Tubes

Postby stratele52 on Thu May 25, 2017 8:49 am

pdf64 wrote:
Factory Guy wrote:
I don't think it's good practice to use lubricating cleaner spray in high voltage areas, eg tube pins / sockets; as the deposited grease may promote dust, solder splatter etc adhering to the area, potentially leading to arcing.
I've done it in the past (when they're de-energised!) and it's not caused a problem that I know of, but don't anymore.
So I suggest to use a deposit free spray cleaner, and if necessary, apply lube cleaner to a cloth and carefully wipe the pins afterwards, avoiding the tube / socket base.



Good quality contact cleaner ( not the one sell at radio Shack ) do a good job. I use it since many years ant it is recommended by Gerald Weber.

Like many tools you use, it is not only what you use, you must know how you use it
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Re: Pulling Pre-Amp Tubes

Postby Factory Guy on Thu May 25, 2017 10:31 pm

You might want to re-read the 1st post, he is USING channel 1 only as he says it sounds better, V1 + V6 with, V2-V5 PULLED. He said both channels worked but he was not happy with the reverb channel and only using the normal channel.

pdf64 wrote:
BigNath wrote:...Leaving them all in apart from V3 and 4 (reverb driver and recovery) seems to keep it nice and quiet and gives me both channels just without reverb..

Factory Guy wrote:The poster noted he was using the NORMAL channel V1 so the removal of the tubes for the vibrato/reverb wouldn't be an issue in this case.

Hmm, to my reading, BigNath seems to say that both channels are operating?
Sound Engineer/Guitar Strangler/Motorcyclist. Not neccessarily in that order... Depends on what day it is :)
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Re: Pulling Pre-Amp Tubes

Postby Factory Guy on Thu May 25, 2017 10:33 pm

Don't know how my name got on this one about the contact cleaner as I never commented on this.

stratele52 wrote:
pdf64 wrote:
Factory Guy wrote:
I don't think it's good practice to use lubricating cleaner spray in high voltage areas, eg tube pins / sockets; as the deposited grease may promote dust, solder splatter etc adhering to the area, potentially leading to arcing.
I've done it in the past (when they're de-energised!) and it's not caused a problem that I know of, but don't anymore.
So I suggest to use a deposit free spray cleaner, and if necessary, apply lube cleaner to a cloth and carefully wipe the pins afterwards, avoiding the tube / socket base.



Good quality contact cleaner ( not the one sell at radio Shack ) do a good job. I use it since many years ant it is recommended by Gerald Weber.

Like many tools you use, it is not only what you use, you must know how you use it
Sound Engineer/Guitar Strangler/Motorcyclist. Not neccessarily in that order... Depends on what day it is :)
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Re: Pulling Pre-Amp Tubes

Postby Vortexion on Fri May 26, 2017 10:40 am

Factory Guy wrote:Don't know how my name got on this one about the contact cleaner as I never commented on this.

One of the pitfalls of using nested quote tags: all too easy to miss out a closing tag somewhere. Good coding practice is always "count them all on the way in and count them all on the way back". :lol:
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