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Topic: effective communication with an amp tech... Ken, Brad, Jim? |
Joe Shelby
From:
Walnut Creek, California, USA
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Posted 10 Sep 2007 11:36 pm |
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I have a 135W twin reverb (installed in a head cab)
that the reverb is buzzing in (buzz increases as you
turn the reverb knob up). My electronic abilites only
extend as far as switching out speakers, replacing tubes, pilot lamps, etc.
The reverb repair would be a straightforward situation for most amp techs (I've replaced the tank,
leads and tube).
But, as long as I'm going to take it to the guy (probably Uncle Spot, in Modesto), I'll probably get
the tubes-all-replaced, and maybe (here's where I'm looking for input) ask him to make component upgrades
that would enhance the amp as it is.
I know that it's important to tell him that I use it for 'clean psg tone,' and that I'm not looking for mods (except maybe inverting phase on the 1st channel, reverb on both, indv. bias for each power tube), but just wanting some possible changes in component values that will make it 'moreso' than it is now.
Joe. |
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Ken Fox
From:
Nashville GA USA
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Posted 11 Sep 2007 5:02 am
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Joe, sounds like you are on the right track. I personally would add a bias adjust, but not for each tube. Just the usual bias adjust for all 4 tubes should be sufficient. That is OK to do, but I am not sure the expense would be worth the results.
The tone stack on channel one can be enhanced by swapping the 100K slope resistor out to a 56 K. It is a nice mod on channel one along with the reverb mod you are planning. |
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Brad Sarno
From:
St. Louis, MO USA
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Posted 11 Sep 2007 5:15 am
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Joe,
To make that amp a good clean steel amp, I don't think you'll need to alter any original values. What you do want is good capacitors and a couple of upgraded resistors.
The tonestack cap's should be upgraded. 250pf should be upgraded to silver/mica types. .047uF and .1uF should be upgraded to 716p series Orange Drops. Also there are a couple of caps in the direct signal path that should be upgraded to the same series of Orange Drops. The cathode bypass caps everywhere should be refreshed (22uF/25V) with Sprague Atom electrolytics. The resistors at the phase splitter could be upgraded with Vishay metal film types. And the power resistors on the power tubes should be upgraded to precision metal oxide, flameproof types, and they should be mounted on the tube socket so that they are just a bit off the socket to be away from the heat. You may also want to upgrade the caps that are around the reverb driver and recovery stages with orange drops. That will help add some warmth and dimension to the reverb sound. You may also want to snip the wire to the tremolo circuit, unless you need the tremolo.
Then good tubes will seal the deal. NOS Jan/Phillips 6L6 power tubes are hard to beat. The new JJ's are also good I hear. Check out the JJ ECC803 tubes for your 12AX7's and 7025 positions. That is JJ's newer tube that's sort of a clone of the old Telefunken long plate 12AX7. Nice tube. The newer Tung-Sol 12AX7's sound good too.
Off hand, that's what I can think of.
Brad |
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Ron Whitworth
From:
Yuma,Ariz.USA Yeah they say it's a DRY heat !!
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Posted 11 Sep 2007 7:29 am
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Hello Joe;
I more thing i would add & the 2 guys above know this because they do it but the average guy does not.
Tell your amp tech after he installs new power tubes that you want the bias adjusted for
" clean all the way to 10 on the volume control "...
He will probably give you a funny look as that is probably not what he normally does for his other customers but this is what you want done for steel.
_________________
"Tone is in the hands. Unless your wife will let you buy a new amp. Then it's definitely in that amp."
We need to turn the TWANG up a little
It's not what you play through, it's what you play through it.
They say that tone is all in the fingers...I say it is all in your head 
Some of the best pieces of life are the little pieces all added up..Ron
the value of friendship. Old friends shine like diamonds, you can always call them and - most important - you can't buy them. |
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Joe Shelby
From:
Walnut Creek, California, USA
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Posted 13 Sep 2007 11:30 pm
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Thank you Ken, Brad and Ron.
I know I'll be able to be reasonably coherent when it
comes time to 'splain m'self.
Ron Veil (Uncle Spot) has probably seen and heard everything when it comes to Fender tube amps, but it's good to know what to ask for, as opposed to "gimme some killer steel tone"...
Joe. |
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