The Perfect Swell

By John LeVan

In the quest for the Holy Grail of tone, there are thousands of mods out there. But before you spend a fortune on the latest fad, consider a few easy changes that can bring you closer to the tone of your dreams.

MAINTENANCE

Before cashing in what’s left of your 401K on amp mods, invest a little time and money maintaining your amp. Recently, I spent some time with my friend Sarge at Creation Audio Labs® in Hermitage, TN outside of Nashville. Sarge had some great advice on keeping your amp in top condition.

1. Keep it dust free. Clean the pots and circuit boards with a non-residue contact cleaner. Always follow contact cleaner with compressed air.
2. Let your amp cool for at least 10 to 20 minutes before moving it.
3. Have your tubes tested/replaced every 4 to 6 years, & check the bias.
4. Replace your capacitors every 6 years.
5. If you have a vintage amp, make sure it’s properly grounded!

CLEARING THE DUST

The buildup of dust and dirt inside your amp can cause a host of problems. From noisy output signals to full blown circuit failure, dust can be a vicious enemy. I recommend cleaning out the dust twice a year. Always turn the amp off, unplug it and let it cool off before blowing it out. Use a non-residue electronics cleaner (Tefron Lube®, Contact II Tech Spray®), and follow that with a can of compressed air. This will prevent many of the most common issues with amp failure.

COOL IT, PAL!

One major reason why tubes fail is caused by jarring the amp when the tubes are still hot. Let it cool 10 to 20 minutes before you move it around. Your tubes, as well as the rest of the amp, get very hot. A sudden jar can and will cause failure!

TEST YOUR TUBES AND BIAS!

If your amp is sounding too thin, too muddy or just distorting more than normal, you may need to replace your tubes. Before replacing them, have them tested by an expert. Testing can determine whether they are blown, weak or just mismatched. A well-matched pair of tubes will make a dramatic difference in your tone.

Biasing is simply matching the voltage of the amp to the tubes to achieve the maximum clean output. I added a potentiometer to make it easier to adjust the bias on my amp to match my tubes. The bias can be tweaked to give your amp more distortion or a cleaner tone. The hotter the bias, the more distortion you get. Keep in mind, a hotter bias may sound better for distortion, but it will burn up the tubes faster. Of course, that’s never stopped me from running mine hotter! There are two ways adjust the bias; technically (using a scope) and sonically (by ear). Both are acceptable methods when done by a professional.

CAPACITORS AND OTHER DEADLY AGENTS!

The capacitors in your amp are like a battery that holds an enormous amount of voltage. When they leak, it causes the amp to sound weak, noisy or like a 747 is flying through it. Sarge recommends that you change them every six years. NEVER touch a capacitor! Even if your amp has been unplugged for days, discharging the caps improperly can KILL YOU! I’ve been bitten by these little monsters and it’s not fun! (another good reason why I don’t work on other people’s amps). Always have this done by a qualified amp tech.

ARE YOU PROPERLY GROUNDED?

If you have a vintage amp like I do, it probably isn’t grounded. I have an old Vox® out of a Thomas Organ® that I tricked out many years ago. The first thing I did (after getting shocked at rehearsal while grabbing a microphone) was install a new power cable with a ground (3-prong plug).  Grounding your amp is very important to staying healthy! Again, I encourage you to take your amp to a qualified amp tech if you have (or even if you don’t) any doubt about installing one yourself.

BEFORE YOU MODIFY ANYTHING, TRY THIS!

A common mistake players make is to try various mods to get the right tone without considering what they are working with. I have discovered 5 things that can radically change the tone of your amp.

1. Changing tubes, trying different types and brands.
2. Experiment with different speakers, ceramic, alnico, etc.
3. Try a different speaker transformer.
4. Different rectifiers produce different tones.
5. Heater mods for preamp tubes.

TUBE MANIA

Most amps come from the factory with cheap, unmatched tubes. There are several brands to choose from; GE®, JJ®, Sovtek®, Svetlana®, Sylvania®, Mullards®, RCA® etc. Each set of tubes must be matched to each other and be the right tubes for your amp. Finding the right tubes for your amp is like having your guitar setup to match your specific playing style. You may need to experiment with several brands before you find what sounds best with your amp. What sounds great in your friend’s amp may suck in yours. My little Vox® sounds great with Sovteks®, but yours may sound better with Mullards®. Make sure your amp tech tests the tubes to make sure they are properly matched.

SPEAKERS

Like tubes, finding the right speaker for your amp, and what you’re playing, will determine good or bad tone. For Metal, the Jensen® Tornado® may work great, but for country, not so well.  Maybe your amp works better with Alnicos®, Ceramic®, Celestions®, EV® or Bulldog® speakers? What’s your favorite flavor? What about cabinets? 1X12, 2X12, 4X12? Open, closed back or ported? I suggest trying out several different speakers and cabinets before modifying your amp.

TRANSFORMERS

The right transformer will give you plenty of headroom and great tone. The wrong one will make you amp sound like garbage. My little old Vox® had a tiny, wimpy speaker transformer that made it sound like a flatulent goat every time I played a chord! I replaced it with an old transformer from a Fender Deluxe® and it sounds great! Again, it’s all about using the right components that work for your amp, your tone and your style.

RECTIFIERS

To tube or not to tube?  There are tube rectifiers and transistor rectifiers. Both are great, depending on what kind of music you play. For classic rock, pop, blues and country, a tube rectifier sounds great. Tubes have more of a spongy, glassy tone. Transistor rectifiers give you a tighter, immediate attack (perfect for heavy metal and hard rock).

HEAT ‘ER UP!

A great way to reduce noise and improve tone is to install preamp heater circuit. This mod should be done by a professional amp tech. Installing it incorrectly can cause serious damage to the amp.

SUMMARY

To keep your amp in top condition, remember these 5 tips:

1. Keep it clean
2. Let it cool
3. Test them tubes
4. Change the caps
5. Stay grounded

If you have any questions about this, or any of my other articles, feel free to e-mail me at guitarservices@aol.com. Be sure to visit us on the web at www.guitarservices.com

copyright©2009 John M. LeVan all rights reserved

John LeVan

The Guitar Services Workshop

www.guitarservices.com