New Download! Cap codes revealed!

Okay, here's another builder's quick reference for your shop, this time all about capacitor codes. I think that whomever invented capacitors used an Enigma machine to label them.

Screwing up the value of a cap can wreck a tonestack or completely alter the sound of your interstage signal. I can never remember how to go from pF to nF to uF to wtfF without looking, so here's a cheat sheet to help us keep it straight if you're the same way. Enjoy!

DIY Electronics Swap Meet August 19th

Man, I wish I were still in Northern California so I could attend this!

According to the annoucement of the meet, "Suggested items to bring for sell or trade include musical instruments, amplifiers, electronic parts and supplies, electronic assembly tools, technical books, electronic test gear, electronic kits, etc." Might be a place to find some good projects or parts.

The swap meet will be at the seminal punk club 924 Gilman St. in Berkeley, CA on August 19th. Hours are from 11am-3pm. Get the full scoop on the DIY Electronics and Musicians swap here.

NOStalgia - the fragrance for tube geeks

Speaking of downloads

In my post yesterday, I linked to a ton o' vintage electronic texts. But if you're only going to download one reference manual for tubes, you need to get the mother lode—the Radiotron Designer's Handbook, Vol. 4. This is the book for anyone serious about learning tube technology.

Be forewarned: at north of 1,400 pages, it's frickin' huge. Don't even bother trying to print the whole thing unless you have a ream of paper handy. Still, worth every second of download time.

For an math-challenged person like me, the chapter on mathematics was worth the whole download.

Incredible digital library of out-of-print tech books

I grokked this amazing site chock full of out-of-print tube tech books over at 18watt.com this weekend (good find, Bentaro!).

I downloaded about 100 million hours' worth of reading material in my quest to understand what the hell the Miller effect has to do with anything. This morning on the Metro I was in full Millertime mode.

Downloadable tube pinout guide

I don't know about you, but I'm constantly having to look up the pinouts of tubes during my builds. Even when wiring common tubes that I have memorized by now, such as the 12ax7, I invariably have one last look at the data sheet just to make sure before the power up. After all, nobody likes 300 volts on their grids.

But here's the problem: In the middle of a build cycle, my shop tends to get a little messy, so data sheets get buried, laptops are upstairs...you know the drill. So I decided to make up a printable, standard-letter sized sheet with all the pinouts for the most-used tubes in amp building. Now I can just tack one sheet to my shop wall for those last-minute sanity checks.

Feel free to click here to download the tube printout guide for use in your shop. You'll need Adobe Reader to open and print it, but I think almost everyone has that these days. I hope it makes your builds go a little bit faster and easier.

Keeping your plates original

I often get emails from customers with semi-designed faceplates or instructions for font choices that they find appealing. This is great! It's always cool when customers know what they want.

But at times, what someone wants is what everyone wants. Take the top two fonts for Amplates.com design in the last two years: Magneto and Deftone Stylus. These are two very cool, retro fonts, but they are becoming victims to their own popularity. If a customer really wants to go with one of those, then hey, by all means, we'll do it. But I try to steer customers to other, also cool script fonts if possible. A lot of my customers aren't aware of the wealth of font choices at their disposal. That's where my experience comes in:

Why not try some new-school retro fonts like Nougat or Hamburger Heaven? You too, can be a "Saucy Millionaire"! In fact, there are literally thousands of fonts to choose from, and I can recommend something that will look cool, be very readable, and will stand out from the crowd.

What's more, we can use those fonts as a starting point to design a completely original logo to truly brand your amps. I'm a big believer that whether you make 1 amp or 10,000, quality and originality count.

17 Things I Wish I Knew Before My First Guitar Amp Build

DISCLAIMER: USE AT YOUR OWN RISK. THERE ARE DEADLY VOLTAGES AND CURRENTS IN ANY TUBE AMPLIFIER AND YOU CAN KILL YOURSELF IF YOU DO NOT KNOW WHAT YOU ARE DOING. THE BELOW TIPS ARE FOR GENERAL REFERENCE ONLY.

1. SAFETY FIRST! Go read and study up on electronics safety. The GeoFX blurb on safety is a good start.You can kill yourself by doing amp work improperly!

2. Never put two hands inside an engergized circuit, EVER. One hand in the back pocket when taking voltage readings or chopsticking components.

3. Chopstick with a wooden chopstick, not a pencil. Graphite conducts!

4. Discharge the filter caps before working inside an amp. To do this, wire a 100K/1W resistor with insulated alligator clips on both ends (use some wire on one end of the resistor to give yourself some slack to work with). Be sure to shrink wrap any exposed resistor leads. Clip one end of the tool to the chassis, and then clip the other to the + side of the first filter cap. Use your meter to verify that no voltage remains on the cap before working on the amp. Make sure you remember to remove the discharge tool before powering the amp back up!

5. Learn to solder a proper joint BEFORE starting the amp wiring. Heat the turret and component (with a heat sink for capacitors and diodes) and flow the solder onto it. Don't "blob" it on.

6. Learn to read a schematic before starting your project. It's not hard, and if you start on an old Champ schematic, you'll learn all the basics right away.

7. Read the P1 Theory Document, even if you're not planning on building a P1. You won't understand everything, but it's a GREAT way to learn how amps work.

8. After you've wired your amp, go through a copy of the schematic connection by connection with a highlighter, making sure everything is there and properly connected. You will find at least one error, guaranteed!

9. Don't just turn the finished amp on. Get Paul Ruby's start-up guide and use it! Transformers are very easy to kill, and very expensive to replace. Be extremely careful on your first power-up. If you use Ruby's guide, 99% of the time, you will be golden.

10. To reduce filament hum, the center tap on the 6.3V secondary windings should be connected to the cathode of the power tube, not ground (this applies to cathode-biased power amps only). If your transformer doesn't have a center tap (if it only has two green wires, with no green/yellow striped wire), wire up two 100 ohm resistors to make a "poor man's center tap". Solder one end of each resistor to either green secondary lead, and solder the other sides of the resistors together. Then run a wire from where the resistors meet to the cathode pin of the power tube.

11. Plan your amp carefully, and use a paper template to mark your chassis for drilling. Use a center punch on all holes, and remember, you can always make a hole bigger, but never smaller...take your time.

12. This photo shows the proper way to wire an input jack. (Photo is from the fabulous Ampmaker.com kit build guide.)

13. When choosing a power transformer or output transformer. Pay close attention to the current handling capabilities, not just the voltages.

14. Use 600V teflon wire!

15. Never use 1/4 watt resistors in a guitar amp. 1/2 watt should be used in most signal paths, and 1 watt most everywhere else, unless the schematic specifically says otherwise.

16. When using shielded wire for signal leads, only ground one end of the shield, and shrink wrap the other end to make sure the metal braid doesn't short anything out.

17. Leave the "power" switch in the "on" position while working on an amp, and turn it off by unplugging it from the wall. This will keep you from accidentally forgetting that even with the switch in the "off" position, you have 115VAC on the terminals of the switch and, in some cases, fuse housing.

To parallel or not to parallel, that is the question

There is an interesting discussion going on over at AX84.com right now about the benefits and drawbacks of using paralleled preamp tubes.

I've used paralleled 12ax7s and 12au7s in clean amps with success, but found them to be a bit mushy in higher gain situations. Turns out I may not have been using them correctly for the higher gain settings. To check out what the gurus have to say, hit the link to the discussion on AX84.com.