Sound Garage Tales

Jason Spencer demonstrates the Fender Hot Rod Deluxe electric guitar amplifier. Sweet one!

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I started using this clever 3 Way Input for all my 2 x 12″ Speaker Cabinets last year, found in Dave Hunter’s The Guitar Amp Handbook, a fabulous book that every serious guitar player should read it. Dave writes with a clear, accessible lingo, and the the book gives instant access to some of the most important aspects and facts of the guitar amplifier, revealing the myths and hypes of the cork-sniffers that are floating out there.

I can’t tell how much flexibility it adds to the way you can use a regular 2 x 12″ (or 2 x 10″ for that matter) speaker cabinet! In a nutshell Dave writes:

“Here’s a cool little mod that I’ve put onto a number of my own speaker cabs, especially those with mix-and-match speakers of different characteristics that I tend to use a lot for recording in addition to gigging”

I am using a blank cabinet dish drilled for three input jacks (preferably UK made switchable Cliff), and wire it up as in the diagram below. Make sure you respect the speaker polarity connections on it, otherwise you might end up wiring them out of phase, and your speaker cabinet will sound weak and boxy due to the two speakers canceling each other.

This way, your regular 2 x 12″ speaker cabinet becomes super-flexible to be used in multiple settings such as:

• a “virtual” 1 x 12″ speaker cabinet by tapping into one of the speakers individually (8 ohms/each), capturing each of its own particular flavor in a recording session.
• a regular 2 x 12″ with both speakers connected in series at double their impedance (16 ohms)
• stereo configuration speaker cabinet, running two guitar amp heads into each individual speaker input (8 ohms/each)
• a 4 ohms total impedance speaker cabinet for amps that have multiple outputs of a single impedance (Fender, etc.), using two speaker cables for each jack in a parallel connection.

Here is the wiring diagram I am using for my Gabriel 2 x 12″ Slant Speaker Cabinet with convertible back, but the mod can be used on any 2 x 12″ or 2 x 10″ speaker cabinet configuration.

Pop in a combination of Celestion speakers of your choice, (I prefer pairing the 8 ohm AlNiCo Blue Celestion Speaker with a 8 ohm G12M Greenback Celestion Speaker speaker) and you will have an outstanding sounding and very flexible speaker cabinet!

UPDATE (Dec 20, 2011): On of my blog readers, Lee Campen sent a parallel wiring version diagram that will actually let you use two 16 ohms speakers. This way you can tap both of them at 8 ohms or each one separately at 16 ohms each! Thanks Lee!!!

So, I guess this is my first “official” demo of the Gabrièl V18 guitar tube amp. I just can’t believe after all these years I didn’t do any!
I had a couple attempts, but I tossed them because I thought they were “un-professional” or ugly, or I do to many “uhms”, etc. Slowly I am realizing that I will never get a perfect video, with a perfect script (Dang! I even tried to memorize a script – so LAME!), and all that!

I decided that in the end I’ll post an un-edited video just the way it is. This way hoping that the listeners will connect with the human, prone-to-failure part of me in some mysterious way, and hopefully get something educational out of it too! Heck if Julia Child did it… 🙂

I will have to say that Ed Dale’s videos of The 30 Day Challenge were of IMMENSE inspiration for me, right at the moment when I wanted to throw in the towel!

So, ladies and gentleman here is the unedited, uncut, first video of the Gabrièl V18 guitar tube amplifier:

Wiring a tube guitar amplifier heater can be a pain in the rear. From twisting the leads to cancel out hum, to routing the 18 AWG wire the whole operation can be a hard animal to tame.
I’ll show you a couple tricks in this video on how you can do it. Enjoy this tutorial in 3 parts!

And once you’re done please give it some social love from the bookmark link below. Thank you!

As Bon Scott of AC/DC said “High voltage rock ‘n’ roll”, these two items go together had in hand in guitar amplifier building.
But really, the Low Voltage can be extremely dangerous because in the end it is the current that is the one that kills.
We are getting shocked daily with 27-30,000 Volts, sometimes not even noticing – for example when we pull off or on our synthetic sweaters or getting out of the car and touch the door handle on a very dry day.There is a Golden Rule on safety when it comes to guitar tube amplifier building:

Always have one hand in your pocket when poking inside and amp chassis!

The reason is that you can still have one hand available to pull the power cord out of the outlet. Another important advice:

USE YOUR COMMON SENSE! (don’t be dumb! 🙂

Don’t touch things you suspect having live lethal potential. You wouldn’t touch a hot pot sitting on the stove if someone mentioned that to you, right? Well, I AM MENTIONING that:

THERE ARE LETHAL ELECTRICAL POTENTIAL IN THE GUITAR AMPS AND YOU SHOULD SIMPLY NOT BUILD OR SERVICE THEM IF YOU DON’T KNOW WHAT YOUR’RE DOING!

(you can use that as a disclaimer)

Here is a list that you should go through to learn about electrical safety:
1. Use a good quality power cord and don’t mess with the plug’s connections.
2. Stay away from 3-to-2 prong adapters.
3. Make sure your house has grounded outlets. Use an outlet tester.
4. Don’t improvise. We do that in jazz or cooking.
5. Make sure your work area is dry and preferably carpeted. It is wise to wear snickers with a thick rubber sole.
6. Install a ground fault circuit interrupter (GFCI) and use that as the outlet for testing amps.
7. For the life of me – have your area well lighten. Many faults can be overlooked in shadowy areas.
8. Use a chop-stick to poke around your components. NOT YOUR FINGER!
9. Electricity still lingers around for many days even after you unplugged the amp. The filter electrolytic can keep a good dosage of lethal voltage. Use the “Filter Capacitor Bleeding Trick“ to uncharged the capacitor explained later.
10. Use a Voltage Test Screwdriver w/ Neon Lamp to test for any suspecting parts that might have live voltage potential. I use this tester ALWAYS when I power an amp up by first touching the chassis with it to see if somehow has live voltage. That should be your preliminary test.

Grounded AC Plug Color Code (USA)
The common color code code to recognize each wire’s role in a grounded AC plug (USA) is:

BLACK: Hot
WHITE: Neutral
GREEN: Ground

Filter Capacitor Bleeding Trick
I use this cheap trick to make sure I squeeze out every possible leftover potential from the filter capacitor:

Considering that the amp-to-be-serviced is working, strike a power chord on your guitar at a pretty loud volume, preferably a A minor 🙂 then immediately hit the ON/OFF switch to off. You will hear your sound trailing away to nothing as a result of the charge being bled out of the filter capacitor to a voltage that’s safe to handle.

To be sure, you can also check the leftover voltage in the filter cap with aVoltage Meter set to the (at least) 500V range.

Having these rules in mind together with a healthy respect for electricity, will give you a surprise free guitar amplifier building.

Even now as a grown up man I sense some of my childhood excitement when I open a kit box of some kind. So much more boxes containing different types of guitar amp kits, that I can actually put them together and (with some mild luck) have them working!!

But some of that excitement is blown away when I discover that certain guitar amp kit wont fit certain cabinets or that the instructions are written in high-language that only Electrical Engineers understand.

There are certain advantages in purchasing guitar amp kits as opposed to scoring the parts and trying to match them together. One of them is that the kits manufacturer (hopefully) already included everything you need to build it, saving you the pain of ordering the parts from several different parts, paying shipping, re-searching parts numbers, etc., only to discover that you ordered the wrong items, or some of them do not match etc.

The disadvantage is that you are locked to the kit’s seller choice of components. But even here you can take some cautious liberty in using for example a higher quality tube or capacitor, etc. Just make sure you replace the component with a similar voltage or wattage, rating, etc.

There are several different guitar amp kits manufacturers out there with great sounding amp packages, like Gabkits (for cabinets) and Ceriatone (for compatible kits, etc.).

These offer the first time builder an excellent choice for an exciting and successful build.

I will be sharing more tips, resources in the following days about the fascinating subject of guitar amp kits.

Fellow Chicagoans,

Check out tomorrow’s (Feb 19, 2008) Chicago’s WGN (Channel 9) Morning Show, where the Gabriel Voxer 18w will appear manned by the outstanding guitar player STIK and his band 1969 in a very cool live performance. It will appear on and off so stay tuned.

I will also record the whole show and post it later on.

I’ve being distributing these newer style FootSwitch boxes but I thought they would first be announced in my blog. Check the engraved “Gabriel” logo. I should probably place a blue LED inside so that you’ll have this eerie light emanating through it. Kinda cool huh??

I know it is a late notice, but here they are:

The Voxer 18 LowCarb will make a cameo appereance on ABC’s Good Morning America with Billboard’s Top New Country Artist of 2007, Jason Michael Carroll, this Thursday, January 17, for a live performance that will include his second smash single, “Livin’ Our Love Song”.

Also around the same date (TBA), the Voxer 18 will also be seen on Chicago’s WGN (Channel 9) Morning Show, manned by the outstanding guitar player STIK and his band 1969 in a very cool live performance.

Earlier last summer I got a customer (thanks Taylor!) asking if there is anything ELSE that can be done in terms of Gabrièl amp skin color schemes – other than the given one, specially now that the Bumblebee is temporarily in his bee hive, hibernating (for a while that is).
I wondered how come it didn’t hit me between the eyes the fact that I can “invert” a color scheme (in this case the Cappuccino) giving a whole new design, with its own personality but retaining the same identity to my amps.
That’s how the “inverted” Cappuccino came into the world. A couple pics here.

So what do you think of it???