Do I need a new preamp valve in my Hartke HA3500?

[kryptonicwatermelon]

Hey all,

I have a secondhand Hartke HA3500 that I really like. I always use the tube preamp, and I usually play for 2 or 3 hours a day. I have it about half a year now, I don't know how long the previous owner had it. Usually it works normal, the tube preamp doesn't give any noise and is pretty loud. When playing in my room, I set the master around 10 o'clock and the preamp about 12 o'clock, with the volume on my Precision not higher than maybe 20 percent. This gives me enough volume. Today I switched it on, and with the same settings it was barely audible. When I turned the preamp up to about 3 o'clock, it was very noisy and the volume wasn't even at the normal level. Turning the volume on my bass up did make it more noisy, but barely louder. I tried switching cables, different basses etc without result. It's not a ground issue, I use the same power outlet as always etc. What I find weird is that when I turn the tube preamp all the way down and use the solidstate preamp, the sound doesn't get louder or less noisy.

When I plugged my bass directly in the effects return of my amp to bypass the preamp, I got a noiseless sound.(not as loud as normal, but I guess that's normal 'cause I'm bypassing the preamp. Correct me if I'm wrong.) So, I think the power stage of the amp works as usual etc.

A couple of minutes I tried it again with the tube preamp etc at normal settings, and surprisingly it was pretty darn loud and noiseless, just as usual. This is how I know my amp. But, after playing for a while, it went again to super low volume and super noisy. Since it's just 1 tube in the preamp, I don't think it's an issue with giving it enough time to warm up.

After what I've read the loss in volume and noisy sound are signs of a dying tube. Can you tell me if this is right? I guess I've eliminated all other factors like cables, bass, cab and powerstage, so only the tube in the preamp remains.
(fyi: here in the Netherlands it's about 30-35 degrees celsius now, could all the problems with my amp be because of the very high temperature?)

I'm glad I discovered this while in the holiday when I don't gig, and the amp didn't crap out during a gig, but I really want to fix this problem before I start gigging again.

I hope you can help me! Thanks in advance,

Reinier

Edited August 19, 2012 by kryptonicwatermelon

[Graham]

Yup, that sounds exactly like the pre-amp valve has gone, I used to have a Hartke model 1000 and found the exact same thing happen, swapped the tube for a new one and it was back to normal :-)

[kryptonicwatermelon]

Thanks mate! I guess replacing the tube will solve the problem then. I hope when I got a new tube I will remember to post if it solved the problem!

[brensabre79]

The solid state pre should still be working fine if its just the tube shouldn't it? unless it goes through the tube first and then through the SS.

Either way, might be worth replacing the tube anyway they don't cost much, unless you stick a NOS Mullard in there like i did

[Graham]

From what I remember, the SS pre-amp didn't work either when the tube went, which worried me until I swapped the valve out

[4 Strings]

New valves aren't expensive, just give it a try. Surprised though, they normally last the lifetime of the amp.

In the UK its a valve, a toob in the US. Had to release my irritating, apostrophe spotting there.