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how to tell when your amp needs a tech

1330 Views 4 Replies 4 Participants Last post by  red5
i bought a fender hot rod deville 410 about 18 months ago. nice enough amp. in the last week or so i think i'm noticing a decrease in it's treble response. to the point where playing bridge evo in my jem straight into amp just doesn't have that hard bite.

this is my first tube amp so i'm willing to accept that maybe i haven't followed tube amp ownership procedures to the letter. things like waiting for 10 minutes to warm up <- ain't for me. from what i've read tubes can need replacing yearly... or never.

i gave it a small hiding today and checked to see that all the tubes were getting a nice glow. they were. admittedly, i don't have the greatest ear in the world, but this is bugging me a little. is it a common symptom of an amp in need of a visit to the doctor? new tubes?

i guess i'm hoping for a little tube amp ownership 101 here!
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As far as tubes, it all depends on how much the amp is used. If you play it a lot, it may well be due for power tubes.

If you bought it used, you probably don't know how old the tubes are. It couldn't hurt to replace them and see if that doesn't solve the problem.
i play about an hour or so most days. bought it new. but like i said, i don't necessarily let it warm up for very long.

1. so it'd be power tubes that would most likely need replacing?
2. is it just a matter if plugging in a new matched set? or does it need to be biased, etc. by a trained tech?
3. is there an appreciable difference in different makes of power tubes?
If it has the original "Groove Tubes" 6L6 power tubes, the least expensive way to go would be to order a new pair of matched Groove Tubes with the same "power rating" as the ones in there now. The power rating is a number that Groove Tubes assigns, based on the distortion ratio of the tube. The higher the number, the hotter the distortion. A tube rated at 7 will break up sooner than one rated at 3.

For a nice upgrade over the GTs, order a set of JJ/ Tesla 6L6GC tubes. Take them and your amp to a qualified tech for a re-tube, bias adjustment and an overall checkup.
New tube time...

Preamp tubes tend to be good until they die or start making funny noises. They are also plug and play.

Power amp tubes die but still work but just don't sound good. I would recommend getting some SED "Winged C" 6L6's (NOT SVETLANAs!) from www.thetubestore.com or www.tubedepot.com and getting the amp biased to them. They test the tubes at how hot they run and match them and are a bit cheaper than Groove Tubes. Additionally, Groove Tubes rebrands tubes and usually do not rebrand SEDs which happen to be by a longshot the best power tubes made today in terms of all around quality and sound.
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