Ask Amp Tech Expert Skip Simmons

i just purchased a valco supro 1953 i actually stole it for 125 bucks the model number is x25308 from what i can tell it is all original and i bought it from the original owner i even have the supro guarantee bond that came with it "even though i believe it has expired haha" anyway somebody has replaced the power cord with a lamp chord which i know is to smal of a chord but the tubes seem to get quiet warm and even the box gets a little warm my first question is isthere a way to clean the tweed cover and my other is what would it cost for me to have you check it out and change the power chor continue reading...

OK, so you've been practicing a lot at home and getting a good tone from your amp. Now you go down to the afternoon jam at the club, set up your stuff just like you do at home, and what the heck! Your amp sounds completely different. continue reading...

Hi Skip,

I just got a used Fender '59 Bassman Reissue. My intentions are to play Punk, Rock, & some Blues with it and I am using a decent crystal element. I have a few questions if you don't mind.

1) First of all, what's the "Ground" switch for? And how do I know if it's on or off?

2) What's the advantage of the Standby switch? Why would you use that as opposed to just switching the amp off?

3) What's the Presence switch for? Where should it be? continue reading...

I often hear from players that say they can't hear themselves at jams and want to talk to me about about a bigger amp. Jams that are too loud are a problem, and bringing in a bigger amp just in case it gets loud is really a pain! However, this is a people/politics problem, not a gear problem. If it's blues, it's blues. If it's blues-rock (or just flat out rock), then you need either careful miking into the sound system or a BIG amp. The best solution is to find a groovier bunch of people who like to play at lower volume! continue reading...

Well, all you harp people out there know that I don't mess with newer amps too much, but I have always said that the Fender Blues Junior offers amazing sound for the money. Recently a customer brought a Blues Junior, along with a vintage amp, and asked me if I had any easy suggestions for Blues Junior harp mods. At first I said lower-gain preamp tubes would be the only thing I would suggest.....those printed circuitboard amps are no fun to modify! continue reading...

A recent question on the forum has inspired this tip. When substituting preamp tubes in an amp to help with volume, tone, and (especially) feedback, remember that it is the change in gain that really makes the difference. Sonic differences between say, various brands of new and vintage 12AU7s can be subtle, especially for beginning players, but subbing any 12AU7 in place of a 12AX7 will really make a big change. So don't worry about buying the "best" tube, just grab a handful and start experimenting!

Skip Simmons

I realise that this is probably a really common question but I'm looking for some advice on changing the tubes on my amp. I've recently bought a Peavey Delta Blues 210 and I'm finding I can't turn the volume up to more than about 2 or 3 without feeding back. The amp has 4 power tubes (EL84's) with a 12AX7 driver and two further 12AX7 pre-amp tubes. continue reading...

The standby switch was originally intended to be a way to silence the amp without actually turning it off. When it was time for your 15 minute break, using the standby switch would effectively turn the amp completely off, but still allow for instant sound without waiting for the amp to warm up. It works great for this purpose. continue reading...

I recently fielded a call from a harp player in Spain with a 4-10 Blues Deville, who was looking for mods that might tame feedback a little. First I said that a smaller amp would be a good idea, but then I suggested disconnecting two of the speakers. He called back a half-hour later and reported excellent results. The Deville's speakers are connected with push-on terminals which makes it easy to "re-wire." Sometimes a loud amp can be a little less prone to feedback with fewer speakers. Try it next time you play a small gig.

Skip Simmons

"If you got something good, put it in your pocket." Thanks to the great Paul Oscher for relaying this wisdom from Muddy.

Skip Simmons