• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Tube Amp Common Mistakes

M

mydog213

Jul 15, 2012
17
0
#1
Hello there, I just bought a tube amp(Ampeg SVT CL) my first tube amp. I noticed one of the tubes looks slightly crooked from the others. Should I be worried?
But the main point of this Thread is to share what you guys think of what are common mistakes you guys have experienced with your tube amps/ mistakes people do/ internal set ups that could possibly lead to malfunction.

Your knowledge can potentially prevent others from screwing their amps up.

THANK YOU
 
#2
First off. Be sure you always have a cabinet plugged in. Almost all tube amps require a speaker load when powered on or else the output transformer will fail. Which is an expensive repair. Also, familiarize yourself with the types of cabs your amps can drive.
I believe Ampeg SVTs are good with 4 or 2 ohm loads. Not sure about 8 ohms.

I take my tube amps to a local amp tech about once a year.
Tube circuits will drift over time and what often is described as "old tubes" is really just a need for re-biasing. Also most tube amps that I own are over 20 years old. So I have capacitors and other junk that needs replacing almost every time I take mine in.

Get to know the eq. Tub amp eq works much differently than solidstate EQ. What may have worked on your previous amp might be too noisy or muddy on a tube head.

Oh yeah, you probably should have posted this under amps.
 
#6
Don't EVER let a drink or any open liquids be on top or even near your head! This is sound advice for any amp but esp. an SVT. Wouldn't want to see that go sizzle-pop-frizzlefry while on the working end of it!

You've come to the right place. I found this site a few months ago while surfing for recommendations on replacement power tubes for my CL and have found a ton of great advice on here about all aspects of SVT's. Learn to use the bias adjustment on the back. There are threads on here somewhere to walk you through it. If you can't get it to correct bias by that take it to a tech.
 
#7
When I was talking about not pulling by the glass, I wasn't really talking about fingerprints, but just yanking the glass off the tube and losing the vacuum. Did that to my favorite set of NOS power tubes about a month ago.
 
#11
I'm sure one major mistake that is made is moving the amp around while the tubes are hot. Once the tubes heat up, the parts inside become quite delicate and can be damaged if they are shaken.

I try to let the amp cool down for a good 10 minutes after a long jam to ensure the tubes are cool enough to transport the amp. Ideally I'd leave it 15-20 minutes before moving it.
 
#13
I know this has been beaten to death, but...
Something that a lot of folks fail to realise that gives a lot of fuel to the "tube amps are unreliable" wive's tale, is that ALL amps (including solid state) need to be serviced from time to time. When You hear about someone having some trouble with a 20+ year old (closet classic) amp that they scored, the likelyhood that it is because of it being "unreliable" is very slim. Simple fact of the matter is, kept properly maintaned they are just as or more reliable than anything else. One of My amps is almost 40 years old and keeps on rock'n, without fail. Yes, it does get a trip to the doctor every so often, but that is part of the game with anything.
I think of it this way... Kind of like the guy that buys a new car and never changes the oil or has it serviced, then calls it "a piece of crap" when the engine locks up.
 
#16
Muckaluck said:
I'm sure one major mistake that is made is moving the amp around while the tubes are hot. Once the tubes heat up, the parts inside become quite delicate and can be damaged if they are shaken.
Click to expand...

Not a bad idea, but not entirely true, either. Tubes and tube amps are actually a lot more robust than people think they are. Car radios used tubes and got bounced around like crazy. A lot of these circuits were originally designed for radio equipment - the very same radios and transmitters that were used regularly by the military. An SVT would probably be perfectly happy to bounce around in the back of a tank. Why not? It's built like one! :D

Where your idea does hold water, though, is when it involves sudden temperature changes. So, while you're probably fine moving your tube amp right after you finish playing, you might not want to take it right out to your car in January. Likewise, if you bring it inside from the cold, it's a good idea to wait a while for it to warm up to room temperature or close to it before you fire it up.
 
#17
grinx said:
old wives tale?

wipe fingerprints/grease/oil off of the tubes before you turn them on otherwise heat buildup on those areas could weaken/break the glass?
Click to expand...

True of quartz lamps and some high-pressure gas discharge lamps, but I don't believe tubes get hot enough for that to be an issue.

JimmyM's mention of pulling tubes by their bases rather than the glass may be a reference to that or, more likely, to the fact that if a tube gets yanked on hard enough it can break at the base, and there's no fun quite like a hand full of broken glass - except maybe hot, broken glass!
 
#20
Use common sense and treat the amp with respect.

It depends on where you live but thermal shock is not good any amp. If the amp is cold, let it warm up to room temperature before turning it on. Also let the amp cool down before taking it out into the cold. This also helps prevent condensation inside the amp.

When transporting the amp, take care to not let it bounce around too much.

If a tube is not straight, it might be slightly out of the tube socket. Gently rock it back into place. It needs to be properly seated in the socket. If it is a small 9-pin tube in your CL, it could also be that the pins are bent. If this is the case, remove the tube and carefully straighten the pins with a pair of needle nose pliers. Pin straighteners are nice to have.

When removing a tube, gently rock it back and forth while applying pressure away from the tube socket. Tubes can only fit into a socket one way. When inserting a tube, be very careful to align it with the socket first. Let it rest on the socket and rotate it until you feel it slide into the socket by a small amount. Then gently rock it into place until it is fully seated. Failure to properly align the pins with the socket is the best way to bend the small signal (9-pin) tube pins.
 

Latest posts

Top Bottom
Back