Wednesday, January 27, 2010

Vintage vs. Vintage

I was over at Bruce Collins’ Mission Amps shop getting some demon tweaks done to my Masco amp when I noticed he had two very interesting vintage tube amps sitting side-by-side on the floor: A tweed Fender 5E3 Deluxe and a Gibson GA-6 Lancer. Both date from 1958. Both are in perfect original sonic condition. Both have two 6V6 power tubes, 5Y3 rectifiers, and original (or period correct) Jensen P12Q speakers. I was prepared to beg Bruce to let me plug in and play both amps, but no need. He immediately suggested I do a comparison test.

The Fender Deluxe was without it’s tweed covering but was otherwise intact. The Gibson GA-6 was in near mint condition. They were both in the shop for minor age-related repairs: faulty switches or plugs that cause noise.

While the circuits of the two amps are very similar, there are some differences.

The preamp in the GA-6 is a 12AX7 wired as a grounded cathode, using a 5 megaohm grid leak bias set up, it is not cathode biased... very old school, same as the 5A3, 5B3 and 5C3 tweed Deluxe but the Deluxe used octal, 6SC7 preamp tubes.

The two volume pots and the tone pot are less than 500k, unlike a tweed Deluxe that uses 1M pots for volume and tone controls. Tone control caps in the GA-6 are the same values as the Deluxe.
The phase inverter in the GA-6 is a 12AX7 wired as a paraphase driver, same as the octal preamp tubed 5A3, 5B3 and 5C3 Deluxes.

In the Gibson the plate voltage to the power tubes is a bit hotter then a tweed Deluxe and the power tubes are idling painfully hot at about 14 watts each. Screen voltage to plate voltage ratio is lower then the Deluxe and the 5 watt power resistor used for biasing the 6V6s is 200 ohms vs 250 ohms for a Deluxe and there is no cathode bypass cap on the resistor while a tweed Deluxe uses a 25uF bypass cap.

Power supply filter caps are all 20uF vs 16uf on a tweed Deluxe.

A good running tweed 5A3, 5B3 and 5C3 Deluxe will make about 10-12 watts clean and this particular GA 6 made about 12-13 watts clean with the same size output transformer as the Deluxe.

So… How does this all translate to tonal differences? There were dramatic contrasts in the sound of the two amps. I used my big red bullet mic – which is extraordinarily hot, putting out 1 volt of current when I hit a loud passage.

Both amps sounded good right out of the gate, but the Gibson was clearly superior. The tone is bigger and warmer, with a much more natural sounding tearing on the notes. The breakup was organic and closely coupled to the pressure I put on the mic. To be honest, it sounded beautiful. I would gig that Gibson amp right now.

The Fender Deluxe had a nice vintage tone, but it just could not measure up to the Gibson. Its tone was thinner and less “connected” to what I was doing with the mic and harp. It sounded slightly boxy. At one point a ghost note popped up –the dreaded boogieman of all harp amps – while I was playing the 2-draw on an A harp. The 5E3 Deluxe amp is legendary among guitar players, and I offer no argument there. This is just about how it reacts when faced with a hot bullet mic and a harp played in second position.

The Gibson had absolutely no issues. No ghost notes or cone cry or nasal tone or noise or anything. You would have to do nothing to this amp to make it a killer harp amp: It is already there.

Small amps with two 6V6 power tubes are among the nicest sounding harp amps. They are too underpowered to carry through a loud blues band, but mic’ed or lined out they are wonderful. I sold a 1947 Gibson BR-6 amp last year and I still painfully regret doing so, especially after playing the GA-6 which sounds remarkably similar.

Many thanks to Bruce Collins at Mission Amps for graciously allowing me to thrash two very valuable vintage amplifiers. Bruce is also the drummer in my blues band, Roadhouse Joe.

Tuesday, January 26, 2010

Hohner's New Retail Strategy

$27.99 at Guitar Center. Hohner will institute a 10% price hike in February, presumably to pay for all this packaging.

Looks Good; Sounds Good

1953 Masco ME-18 tube amp and Epiphone cab

Thursday, January 21, 2010

Random Notes

-Last night I had the chance to play through a Peavey Delta Blues amp that belongs to harp player Elwood Barrett. It was the 2x10 model, an amp I’ve tried and liked before. I didn’t have a lot of time to dial it in, but I was able to get a nice tone from the amp, even though it was completely stock. It seemed I had to dig in pretty hard to get it to crunch. Feedback was a bit of an issue. But it was fun. I played two sets with the amp at a jam at Q’s BBQ in the Cherry Creek area of Denver.

-I ordered a harp mic from
Front and Center Microphones. Ronnie Shellist raved about these mics, and I had the opportunity to review them myself. Very impressive. Wonderful tone, full and warm, and good feedback resistance. Each mic is hand carved, and Scott at F&C sent a couple of pics of my mic being built.

My mic shell will emerge from this block of Cocobolo wood.

In progress.

I ordered a mic with no volume control, but an on/off button embedded in the shell where I won’t be likely to hit it inadvertently. We discussed which (if any) capacitor to install across the NOS crystal element, and I think we made the right decision. I can’t wait to get the mic and start gigging with it.

UPDATE: Here is a shot of the shell, with the wood for the grill next to it.

Tuesday, January 19, 2010

Doin' my thang

Jan 17, 2010. Ziggies Saloon in Denver.

"Your amp sounds like it's pissed off."

I’ve played out with the little Fender Champ 3 times now at blues jams, one of which my band hosted. At two of the jams I ran a line out from the amp to the PA. At one jam in a smaller club the amp was more than adequate with no PA support. I plan to use it this Friday at a bar gig.

Several people I’ve talked to thought the Champ was now my gig rig, but that is not so. It is just sounding so damn good, and it is the perfect jam amp: It weighs only 21 pounds, sounds best without any effects, and has a great line out. I carry the amp in one hand and my harp case in the other (including and extra 20-foot instrument cable for the line out).

The Champ sounds spectacular with its new NOS paper in oil caps and custom harp voicing by Bruce Collins of Mission Amps. It still has a bit of the Champ-ish rasp, but with a much bigger, more musically complex tone. It has lost all the boxiness and nasal honk. It seems less compressed and more dynamic. The main beauty of the tone is that it just rips. The tearing along the front edge of the notes is gorgeous.

Yeah, you could get carried away with the crunch and overdo it with this amp, and I may be guilty of that sometimes. A guy who knows tone very well said to me it sounded like my amp was pissed off. Perfect!

So many harp players do everything they can to kill the highs in their amps. They lug big expensive 4x10 amps around, cut the highs off, crank it up to 4, and sound like a blanket is thrown over the amp. They are missing the best part of the harp tone.

Having raved about this amp, I gotta say it still does not sound as good as my regular gig rig, the snakeskin 5F2H custom amp. It just can’t. But the Champ is a snarling little bastard that turns a lot of heads. I’m diggin’ it right now.

Friday, January 8, 2010

Upgrading the Fender Silver Face Champ

I decided my Fender silver face Champ needed a line out, so I took it to Bruce Collins at Mission Amps. Well… one thing led to another and the Champ is no longer Champ-like at all. It roars and growls and moans and grunts. This ain’t yer daddy’s Champ.

Bruce had a few ideas to improve the tone, so we kept trying this - then playing the amp - then trying that, and playing the amp again. We ended up replacing all the caps and other components as well. The Champ now has NOS Paper in Oil tone caps!

The little amp already sounded good. Regular readers will know it has a 10-inch Weber 10A125-O alnco speaker and a NOS 5V4 rectifier tube. The preamp tube is an NOS 5751. The power tube is an NOS RCA blackplate 6V6. It was the best-sounding Champ I’d ever heard, but now it doesn’t sound like a Champ. It sounds like a beast.

Here are the changes Bruce made to the circuit of the amp:

2 .068uF/400v Paper in Oil K40y caps
1 .047uF/40ov Paper in Oil K40y cap
2 22uF-50v Electrolytic cathode bypass caps
1 100uF-50v Electrolytic cathode bypass cap
1 .001uF-500v CM Ceramic cap
1 .001uF-630v Mallory 150 cap
1 .0015uF-630v Mallory 150 cap
1 250pF-300v Silver Mica cap
1 150pF-300v Silver Mica cap
1 470 Ohm 5 Watt 6V6GT tube cathode bias resistor
1 47K 1w carbon comp B+ power supply resistor
1 56K 1/2w carbon comp NFB reduction mod resistor
1 220K1/2w CF Line Out mod resistor
1 47K 1/2w CF Line Out mod resistor
1 Mono Jack non-switching Line Out Jack

Now we are looking for a 10-watt transformer with a 4-ohm tap…

The amp sounds incredible. I plan to gig it this weekend and next. Check this out: It weighs in at only 21 pounds! I just need a coiled up cable in my harp kit to line it out to the PA, and Look Out Mama.

Email bruce at missionamps dot com

UPDATE: Here's a link to a sound clip. I'm using a bullet mic with Shure CM element. No effects or editing at all. This was recorded using a Zoom H4 digital recorder about 4 feet from the amp.