Monday, April 25, 2011

Further Tales From the Tonal Fringe: The Sherwood 84-22

I acquired a Sherwood 84-22 a few years ago in a state of disrepair-deshabille might be more like it-and some stinkiness about which more anon, mostly because I liked its looks.

The Sherwood dates from the late forties and was probably sold by Montgomery Wards. It was clear from the beginning that it had been made by Danelectro back when they were in Red Bank and before they'd discovered the uses of Homasote as cabinet material.

The circuit is interesting, as it uses the filament of the first preamp tube as a cathode resistor, in conjunction with a resistance on the ground side-which keeps the filament above ground and dumps the detritus into the center tap of the filament winding. It also runs the 12SJ7 pentode pretty hot which makes for some crunchy sounds-not the typical late forties thing.

Along with the Rola field coil speaker, with modest voltages provided by the iron from the House of Freed, it's got its own groove that owes little to anything else of the era.

The overhaul resulted in some head scratching because the stinkiness got worse and finished up with a cloud of evil smelling smoke and lots of distortion. After puzzling over it I realized I had a similar amp in the collection and on opening it up, it was easy to see where the last owner had bodged the circuit which accounted for the stinkiness and lousy vibrato.

Of course, experimenting with odd circuit ideas was something that happened a lot in the House of Nat Daniel. I've seen several variations on this theme, including one which uses a power tube to modulate the field coil current for a Leslie type vibrato effect, and one that uses a potentiometer to adjust the preamp tube filament voltage for yet more cool Danelectro edginess.

The circuit is the same as the Silvertone 1303, and I've seen it in amps from Wabash, Noble, and Danelectro. As part of a cooperative project I dug up an original copy of the schematic and it was redrawn by Sean Weatherford of Bean Amplifiers, so that was probably the last one the seller got five bucks for.

It is now the world's property, and it would make a great home brew project. Why make yet another tweed Deluxe? This'll get you there in style, plus vibrato to boot.

I've got an 84-23 which is the same amp with an extra 8 inch PM speaker, and it's undergoing a refit as we speak.

How's it sound? Sharp, edgy, and full of fight. It's not smooth at all like a Deluxe but edgy and in your face like you'd expect a guy from Jersey to be.

Monday, April 18, 2011


As described in the New York Times At War blog, Clay Hunt, a marine who had served in Iraq and Afghanistan, took his life March 31 of this year in Sugarland, Texas.

I'm inclined to think Clay Hunt was killed overseas even though he died by his own hand.

My son's a soldier and a healer and has served in the hot zone, and I am often reminded when chatting with him that all we see of most people is what's on the surface, seldom what's stirring in the depths.

Father Martin, having been a chaplain and a world war 2 veteran may have known a lot about this story, even though he's been gone thirty years and more.

Rest eternal grant unto them, O Lord; and let Light Perpetual shine upon them.

Image courtesy of CNN.

Friday, April 08, 2011

Judybox Revival amp

I finished up the Judybox Revival amp and powered it up today. It got topped off with a nice set of vintage Dakaware chicken head knobs I'd been saving for a special occasion.

Here's what I did to it.

Replaced all the ceramic dropping resistors with a 3w metal film, a 2w metal film, and a 2w carbon comp.
Replaced the ceramic 5w screen and grid resistors with 2w Dale metal film and the grid resistors with 1/2 w carbon film from Rat Shack.
Replaced the pilot lamp assembly with a Fender item. This was broken
Replaced the power receptacle. This was broken as well.
Replaced the 40-22-10 e'lytics with 47-22-22 450v items
Replaced the three ceramic octal sockets with bakelite.
Installed 5 standoffs of the proper length to support the board level and not preloaded.
Revised the ground scheme to a star ground setup
Replaced the chassis screws with new stuff from the hardware store.
Installed a smooth plate Tele in the first position.

How's it sound? About the same-bright and sparkly with a lot of depth on the bottom end. Sounds a lot like an AB165 with the bass and treble dimed and the switch on bright.

The builder used Tocos (Tokyo Cosmos) pots-very good stuff-but they're all linear. I may change them out for audio taper, at least the volume controls. All the connects from the pots to the board are shielded wire. I didn't see a nfb resistor but maybe it's there somewhere. I'm thinking that the first two preamp tubes share a common filter capacitor, because if they did not there would be four and there are only three e-lytics. Both preamp tubes have small electrolytics on both cathodes.

I don't know whether I'm qualified as an expert-I'm in the middle of doing a schematic layout and a bill of materials and when I'm done I may be an expert in which case if you find this drop me a line.

I am in a position to make some recommendations in order of importance.
Ditch the power receptacle and pilot light for something good.
Install proper standoffs to support the board and level it out.
Dump all the ceramic resistors except the power tube cathode resistor. They look stupid.
Revise the grounding to a star grounding common-it was strictly from hunger.
Replace the octal sockets with bakelite, Beltons, or military Amphenols

If you've got any questions about this amp, drop me a line.

Friday, April 01, 2011

Tales From the Tonal Fringe, Continued: The Judybox Revival

Sometimes you stumble over something, and as you follow the trail, an entire new world is revealed. People who dig quirky guitar amps are no different, and that led me to the Judybox-partially because it's named after my wife. I decided I had to have one.

The story's quirky. The amps were developed by Al Nelson down in Austin, Texas about six years ago or so, and that's where you'll find most of them. A pretty big splash was made at the 2006 NAMM show which was held in Austin that year, and from what I read on TGP and other forums, the wheels started to come off the project soon after. Deposits were taken and whether they were returned or anyone got amps is anyone's guess.

Suffice it to say there were and are a lot of unhappy people in the Austin area who'd ordered amps and didn't get them.

There are stories of illness and mismanagement, a transfer to shadowy investors, some or all of the assembly being done in China, and that's pretty much where the story ends, in 2007.

The registered address of the business, 8804 Chisholm Lane, looks a lot like a residence with a stable out back. It's owned by a gentleman named Stanley Phillips and has been in his hands since 1972 according to the Travis County Assessor.

Entity Information: JUDYBOX, INC.
AUSTIN, TX 78748-6378
Registered Agent: AL NELSON
AUSTIN, TX 78748
Registered Agent Resignation Date:
State of Formation: TX
File Number: 0800639464
SOS Registration Date: April 10, 2006
Taxpayer Number: 32019547028

Well. What's the story on this orphan?

It's cathode biased, two channels each with its own volume, bass and treble, and reasonably well equipped although looking like it was done in a bit of a hurry. There are no identifying marks on the transformers which look a bit Asian. There are extra taps on the power transformer that could prove interesting.

The tube layout is conventional: 5AR4, 6L6GC, 6L6GC, 12AX7, 12AX7, 12AX7. The voltages are relatively low, with a B+ of only 369v and 309vAC on the legs of the power transformer. Some of the fitments are a little cheesy-the pilot light and power inlet socket are pretty much low grade schmutz plastic, and shot, but overall it looks pretty decent.

Sound wise, this amp does clean in a big way, and it's got a nice deep bass tone that's right for single coil pickups, particularly P90s. The original speaker's been replaced with a Celestion Super 65 that gets the job done well.

Where the story ends, I don't know. If you've got some information feel free to post a comment.

UPDATE 4-7-11
Since I wrote this piece I've been doing the work required to get this amp in serviceable condition and here's what's been done so far..

I replaced the pilot lamp assembly with a military surplus item that the original looked like it had been copied from, got rid of all the ceramic resistors except the cathode resistor, replaced the electrolytics with suitable replacement values, and went up to the hardware store for enough hardware to cook up proper standoffs. This required modifying a few holes and drilling others, but now the board is level, well supported and not preloaded at all.

When you think about it, the screen resistors and grid stoppers do not need to be 5w ceramics, and the dropping resistors do not need to be 10w. 7w and 5w ceramics. Fender did just fine for the last sixty years without that stuff. Plus, smaller resistors make for a cleaner installation and that's the look I'm going for.

Even as we speak the UPS man is supposed to be bringing me a new power socket to complete the job. Then, I can reassemble it and survey the grounding.

One interesting thing I found was the control pots-they're all linear, made by Cosmos Tokyo and very nice looking stuff. I shall try and find a source.