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#1 innovine

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Posted 25 November 2013 - 07:52 AM

I noticed that there is a good amount off hiss coming from my dt25 with the master volume turned fully down. This seems constant as I raise the master (other hiss from the guitar comes in). This also seems related to the topology, with the treadplate being the worst. Any idea what is going on? I thought the master being down would turn the sound OFF, but all it seems to do is cut the guitar off, leaving this hiss. Anyone else get the same behaviour?
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#2 phil_m

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Posted 25 November 2013 - 08:00 AM

Hmm... My DT-25 is pretty much dead quiet - much quieter than any of my other tube amps, I believe. I imagine that hiss could be a sign of tube going bad. Has this just developed recently, or has it always been this way?


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#3 innovine

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Posted 25 November 2013 - 08:30 AM

I dunno. Possibly a while. I moved my gear around and I'm sitting closer now and notice it more. Plus using the treadplate is new for me too. I think I've always noticed some mild noise floor tho even with the master fully down
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#4 moogary

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Posted 25 November 2013 - 09:36 AM

I have the same hiss from the day that I bought it (about 8 months ago).  I plugged it into different outlets, to no avail.  I really only hear it when I'm by myself.  With the band, there is usually so much other noise.

 

I've learned to live with it, but it is definitely much louder that a Twin Reverb.


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#5 kinghomer999

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Posted 06 December 2013 - 04:03 PM

I have a similar issue with my DT50, a fairly noticeable hum/hiss with master volume turned all the way down. It's not a performance issue as live things are loud enough to mask it, though low volume practice and studio use is a little rough with it. Will get it looked at sometime soon by a tech I trust and let you know what we find!


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#6 innovine

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Posted 19 December 2013 - 07:57 AM

Yes, the same here. I play at a minimal volume late at night and its annoying. I've taken to switching to Triode and that clears it up a good bit.
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#7 geppert

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Posted 19 December 2013 - 03:38 PM

I had similar problems when I first got the DT25 … changed power tubes, re-biased, 80+% better for sure.


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#8 Brazzy

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Posted 19 December 2013 - 06:33 PM

I have this hiss (white noise?) the OP has but in a DT50 and am prepared to replace the tubes, but I've been using it and it sounds ok. This has been there since it arrived by UPS about 1 month ago. At first I thought it was normal and it might be to a certain extent (tube amps nature etc., lol).) Also when I first fired it up and first turn the standby on within a few minutes I heard a fizzy noise that lasted a few seconds and slowly fizzed out and said to myself "WTF was that, lol". Had a few more fizzes since but just kept playing since that's what I have it for.

 

Which tubes did you use geppert?

 

I had similar problems when I first got the DT25 … changed power tubes, re-biased, 80+% better for sure.


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#9 geppert

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Posted 19 December 2013 - 11:03 PM

Brazzy ….I used matched Mesa EL84's in the DT25. There is lot's of tube choices out there. A "matched set" is the key.


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#10 Brazzy

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Posted 20 December 2013 - 08:03 AM

Brazzy ….I used matched Mesa EL84's in the DT25. There is lot's of tube choices out there. A "matched set" is the key.

 

Hey thanks for the tip.


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#11 innovine

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Posted 21 December 2013 - 12:58 AM

Is there any other differences when replacing the tubes?
Is replacing and rebiasing a simple task, or will I be fiddling around in very cramped and uncomfortable places?
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#12 Brazzy

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Posted 21 December 2013 - 07:55 AM

Is there any other differences when replacing the tubes?
Is replacing and rebiasing a simple task, or will I be fiddling around in very cramped and uncomfortable places?

 

I don't think it's too hard but I do have experience building, repairing, fabricateing, and manufacturing many types of products. I think anyone who has the determination to learn can get the right tools and do it with confidence. Take your time and read alot, ask questions and learn as much as you can so you can be confident in yourself.

There are other threads and this might be one of the first. >>> Biasing Thread by whiteop


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#13 stumblinman

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Posted 23 December 2013 - 11:12 AM

Is there any other differences when replacing the tubes?
Is replacing and rebiasing a simple task, or will I be fiddling around in very cramped and uncomfortable places?


Like the back of a Volkswagen?
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