Dumble problem

tubey · Post by **tubey** » Mon Apr 14, 2014 4:26 pm

Hi,

I have made a #183 clone, But now I have a problem and need some advice. Someone used an effects pedal with a to large output and now the fine detailled sound of my amp is almost gone. Is this just the preamp tubes, or do I have a bigger problem?
It's all fuzzy and raspy now. terrible.
Thanks !

groovtubin · Post by **groovtubin** » Mon Apr 14, 2014 5:30 pm

tubey wrote:Hi,

I have made a #183 clone, But now I have a problem and need some advice. Someone used an effects pedal with a to large output and now the fine detailled sound of my amp is almost gone. Is this just the preamp tubes, or do I have a bigger problem?
It's all fuzzy and raspy now. terrible.
Thanks !

does guitar plugged into the FX RETURN on back of amp play ok?

jim@Omegaamps

amplifiednation · Post by **amplifiednation** » Tue Apr 15, 2014 1:50 am

When did you build the amp? How long did it work well?

jcsifu · Post by **jcsifu** » Tue Apr 15, 2014 5:09 am

tubey wrote:Hi,

I have made a #183 clone, But now I have a problem and need some advice. Someone used an effects pedal with a to large output and now the fine detailled sound of my amp is almost gone. Is this just the preamp tubes, or do I have a bigger problem?
It's all fuzzy and raspy now. terrible.
Thanks !

Just a stab in the dark but are you plugged into the FET input with high output pickups on your guitar? I plugged my paul into my FET input once by accident and thought something was wrong with the amp, which sounded hash and raspy. After I plugged back into normal input it was as usual.

Just a quick guess.

tubey · Post by **tubey** » Tue Apr 15, 2014 1:45 pm

Thanks guys for your comments.
I build the amp about six months ago. It worked perfect until someone used a ZVEX super hardon with max volume.
It's the regular input. Thanks for suggesting the FET, it could have easily been that. But I used the normal input.
I'm going to try that effects return ( thanks Jim ) then I could isolate the problem in the pre or power amp. I was bright enough to built the amp, but not very bright in fixing these problems.
I hope its just the output tubes or some small component I can exchange.

amplifiednation · Post by **amplifiednation** » Tue Apr 15, 2014 1:59 pm

I was thinking it might be a bad solder joint that might have been exposed by the high level into the amp. Stranger things have happened. Try isolating the problem, it's probably going to be in the preamp...also i would swap some tubes

ic-racer · Post by **ic-racer** » Tue Apr 15, 2014 6:36 pm

There shouldn't be anything to go bad between the input jack and the first grid except the 22k resistor. I have read of grids melting but have never experienced it. Try replacing the first preamp tube.

bcook · Post by **bcook** » Tue Apr 15, 2014 11:19 pm

A quick check of the tube voltages will tell you if a resistor/capacitor/tube has gone whacky. While you're in there, use your probe to wiggle the wires and whack the relays. Another possibility is a blown speaker...

tubey · Post by **tubey** » Thu Apr 17, 2014 1:58 pm

Thanks for the advice. I'm going to try these things. I have a lot of measuring to do. I hope I will find the problem quickly, because the amp sounded like a million dollars.

The only way I could have ever build the amp was with all the great info on this site and all the contributions of you guys.

tubey · Post by **tubey** » Fri Apr 25, 2014 1:39 pm

So. I've checked everything. All the voltages are OK. The bias is exact how I adjusted weeks ago. Is it possible the NFB resistor is blown?
Is there a way to measure if the OT is damaged?
I feel I miss a great deal in bandwith, with a bit of a fuzzy sound. Swapped the preamp tubes, no difference.
Should I desolder the NFB resistor and check?
I still have to try to plug in the power amp and hear what happens.
Thanks for the advice !

rob@tele · Post by **rob@tele** » Fri Apr 25, 2014 2:02 pm

DId you try with a different speaker? Perhaps the speaker is blown....

tubey · Post by **tubey** » Sat Apr 26, 2014 3:02 pm

It does sound better with my own 4 x 12 at home. Still I feel a loss of bandwith. I'm wondering if it's possible that the NFB resistor is blown. All the voltages are OK. Maybe I got the EL34's worn out, or did I wreck my OT and is there a way of checking this?
It's great to have made this amp, but I have no experience in tube amp problem solving. I have solved some small things in the amp, like switching the primary wires of the OT.... squeel.

groovtubin · Post by **groovtubin** » Sat Apr 26, 2014 11:35 pm

tubey wrote:It does sound better with my own 4 x 12 at home. Still I feel a loss of bandwith. I'm wondering if it's possible that the NFB resistor is blown. All the voltages are OK. Maybe I got the EL34's worn out, or did I wreck my OT and is there a way of checking this?
It's great to have made this amp, but I have no experience in tube amp problem solving. I have solved some small things in the amp, like switching the primary wires of the OT.... squeel.

Find some old capitol radio engineering books from the 50`s n start learnin!

jim@Omegaamps

erwin_ve · Post by **erwin_ve** » Sun Apr 27, 2014 3:42 pm

Tubey, where are you in the Netherlands?

tubey · Post by **tubey** » Mon Apr 28, 2014 10:11 am

I'm located in Hengelo......

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