Tube Amp Only "Works" When Standby Is On..

BassSurfer · #1 01-11-2013, 07:50 AM

Hey guys,

New tube amp owner here after many years and I just have a quick, rather odd, question to ask the experts and amp gurus alike on here. The amp is an Ampeg V4 by the way.

For some weird reason, I am not getting any sound at all when the standby switch is turned off. In other words, when the power switch is activated, there is no sound, but WITH BOTH switches activated, I am getting a sound.

Does anyone have ANY idea why this would be happening? If someone could let me know that would be great and as always, all comments are welcome! If anyone needs me to restructure my question or make it clearer, I would be happy to oblige!

UPDATE: 1/13/2012: The problem has been found. Whoever last serviced it, for some weird reason, "wired it up" and made it function in a way that the Power switch was actually the STANDBY switch and vice versa... who would of known... =/

Handyman · #2 01-11-2013, 07:57 AM

Quote:

Originally Posted by BassSurfer

For some weird reason, I am not getting any sound at all when the standby switch is turned off. In other words, when the power switch is activated, there is no sound, but WITH BOTH switches activated, I am getting a sound.

This is exactly how a standby switch is supposed to work. There is nothing wrong with your amp.

The standby switch keeps the tubes heated, but the actual amplifier is disabled.

hdracer · #3 01-11-2013, 07:58 AM

You are in standby

Febs · #4 01-11-2013, 08:00 AM

If I am reading your post correctly, the standby switch is doing exactly what it is designed to do. This is from the V4BH manual:

Quote:

12. STANDBY: The Standby mode allows the tubes to warm up or remain warm without high voltage being applied to them. This extends tube life. This switch should be OFF when first turning the amplifier on. Allow the unit to warm up for 20 seconds before switching to the ON position. During short periods of non-use, the amp should be put into Standby mode.

vgbob · #5 01-11-2013, 08:19 AM

You will get differing opinions, but if you wish you can just
leave the standby in the 'on' position, and not even bother
with turning it on and off. Just use the power switch.

Bassmec · #6 01-11-2013, 09:12 AM

Quote:

Originally Posted by vgbob

You will get differing opinions, but if you wish you can just
leave the standby in the 'on' position, and not even bother
with turning it on and off. Just use the power switch.

Do you by any chance work for one of the new production tube manufacturers? because if you did that to one my silicon rectifier equipped amps loaded with genalex KT88's you would be wearing your bass as a necklace.

Cold tubes are not best subjected to any form of electromechanical shock especially banging circa 700volts DC straight on a cold tube let alone the dangers of cold surfaces attracting moisture and improving the chances of taking the HT fuse out in an arching tube socket.

Of course if you find you have glass rectifier tubes you don't need the
Standby switch to protect from the shock of instant HT.
Now I am just beginning to understand why kids think tubes amps are less reliable than transistor ones.

RickenBoogie · #7 01-11-2013, 11:10 AM

+1 the reason tube amps have a stand by switch is to extend the life of the all important tubes. Failing to use stand by when powering up will result in premature damage to the amp, which would be a stupid thing to do on purpose.

nysbob · #8 01-11-2013, 11:13 AM

That's the fact!

The standby switch is there for a reason, said the guy who's been playing tube amps for decades without any major issues...that would be me.

On the old V4, when the standby switch is down and lamp's not lit, it's in standby. Flip it up (after you've had on the main power on for a minute) the lamp lights and you're ready to rock.

B-string · #9 01-11-2013, 11:17 AM

Off on a standby switch means High Voltage is off (standby mode). On means HV is on (no longer in standby) the amp is fully on in operate mode.

Mr. Foxen · #10 01-11-2013, 11:41 AM

Anyone who understands care to explain why the standby is necessary for protecting valves? All the serious electrical sorts I've spoken to don't think its for valve protection, its a convenient thing to have for when you are working on an amp, and a mute function. Most of the nicer amps I use don't have a standby, the Matamps have a mute button labelled as such, but it doesn't shut off the HT (might not apply to all Matamps, but its good to be aware the HT is still on if you are poking about in there.).

two fingers · #11 01-11-2013, 11:42 AM

Sounds like your works exactly like mine. That's what it's supposed to do. Both switches up and the V4 will take your head off (in a good way).

B-string · #12 01-11-2013, 11:49 AM

Quote:

Originally Posted by Mr. Foxen

Anyone who understands care to explain why the standby is necessary for protecting valves? All the serious electrical sorts I've spoken to don't think its for valve protection, its a convenient thing to have for when you are working on an amp, and a mute function. Most of the nicer amps I use don't have a standby, the Matamps have a mute button labelled as such, but it doesn't shut off the HT (might not apply to all Matamps, but its good to be aware the HT is still on if you are poking about in there.).

Applying HV to the anode of a cold tube strips electrons from the cathode coating before it is heated. This is only true for SS rectification. Tube rectifiers will not supply HV DC until they themselves also warm up.

Mr. Foxen · #13 01-11-2013, 11:56 AM

Ah, that will be why then, no amps I have operate in the kilovolts range necessary for cathode stripping to be a concern. The Ampeg doesn't, nor do any instrument amps I know of, except maybe the PJB thing that uses a transmitter valve.

B-string · #14 01-11-2013, 12:08 PM

Actually Motorolla proved it to be a concern when exploring SS rectification on TVs. They were going to replace the HV tube with a HV SS rectifier (a expensive move in those days). Drop in emission was found in all tubes after many, many repeated cycles. Their solution for warm-up time was just to keep the heaters on. Cathode poisoning was found to be much less a concern than stripping.

Mr. Foxen · #15 01-11-2013, 12:22 PM

It tube terms, guitar amps don't run on high voltage, they are pretty low in the scheme of things, few hundred, rather than kilovolts, or tens of kilovolts for high voltage. CRT TVs work in this range, unlike guitar amps:

Quote:

As a crude rule of thumb, you can assume that a typical CRT high voltage supply will provide roughly 1kV (kilovolt) per inch of diagonal measure.

http://lowendmac.com/tech/crt_danger.html

B-string · #16 01-11-2013, 12:25 PM

I did not state they were evaluating the CRT only. They evaluated all tubes from oscillators to mixers to gain stages and output stages (AF,Horiz and Vert).

TV's of the time were ALL tube before a SS device was ever used.

Mr. Foxen · #17 01-11-2013, 12:27 PM

Give a citation, or there is no useful info. Nothing here has given me any more knowledge that what I already know to be oft repeated but not correct.

1958Bassman · #18 01-11-2013, 12:32 PM

Quote:

Originally Posted by B-string

Off on a standby switch means High Voltage is off (standby mode). On means HV is on (no longer in standby) the amp is fully on in operate mode.

Sometimes, On means Standby is On and Off means the opposite, like the old Fenders.

johnk_10 · #19 01-11-2013, 12:44 PM

your V4's standby switch is working properly.

B-string · #20 01-11-2013, 12:50 PM

Quote:

Originally Posted by Mr. Foxen

Give a citation, or there is no useful info. Nothing here has given me any more knowledge that what I already know to be oft repeated but not correct.

Would love to if I still had access. I worked part time (while in school) for an authorized Motorolla and Zenith dealer and reapir shop. I don't know if Motorolla archives exist from that era?
I only offer as personal experience. If you require proof the search is yours to do as you asked for information.

Only offered what I know, to be readily discounted if anyone wishes with no offense taken.