Mystery Amp: The Epiphone Kent-or Maybe Asta.

Here's an interesting small amp I acquired recently and it was no stranger to me. I'd been at an auction a number of years ago and bid on it but failed to score it. So I consoled myself with a dolphin head Danelectro guitar. The amp itself showed up on craigslist on Saturday and I made my deal over the phone and picked it up yesterday. It was considerably less than it sold for at auction, plus it had been updated with a grounded power cord.

So then, the question was, what is it?

The unofficial New York Epiphone Registry thinks it is an Epiphone Asta, of which no catalog pictures exist. The amp they show on their site has four tubes-two 6V6s in series no doubt, a 6SL7 preamp, and a 5Y3 handling the rectifier chores.

I have my doubts. It looks awfully similar to the Epiphone Kent shown above from the 1950 Electar catalog, pictured in Epiphone: The House of Stathopoulo  by Fisch and Fred from 1996. This is described as a three tube amp developing 6-1/2 w and a single volume control.

The serial number on this amp is 2136. It's covered in tweed and has a 10 inch Rola PM speaker with a production date of 1949. It also carries a Freed power transformer which suggests that it was made in the New York area.

The extra large sized mud dauber nest is an extra cost option.

Nat Daniel made amps post war for Epiphone but according to him he and Epiphone had parted ways by 1946.

I would respectfully suggest that that is inaccurate, because the redesigned Epiphone amps in the 1955 catalog are quite similar in the panel control placement  and graphics to contemporary Danelectro amps including the placement of the pilot light . Nat Daniel was also known for using Freed transformers.

There is a legend on the later amps that says "distributed by Continental Music Champaign, IL-San Francisco CA-Atlanta GA". In further research, Billboard's list of exhibitors at the NAMM convention for 1951 in Chicago shows Continental Music, a division of C.G. Conn four doors down from Danelectro.

Fisch and Fred go into some detail concerning the relationship between Continental Music and Epiphone. which began in 1952 and continued to the end of the line.

I've yet to examine one of the middle fifties Epiphone amps closely, but I suspect not too many were sold because The House of Stathopoulo indicates that by 1957 Epiphone had become moribund and was acquired by Gibson.

If you have a schematic for an Epiphone Kent you can send it right along.

Debugging The Channel Switching On A Hot Rod Deville

(Note: This probably applies to any other amp in this series that uses a similar switching arrangement-Ed.)
(Note: The numbers refer to the Hot Rod Deville schematic, Fender dwg no. 050384 rev, B)

I've had a Hot Rod Deville here for a while as I was trying to sort out a number of problems. The customer complaint was that it had a sort of a crackle as certain notes trailed away. I concluded that it was one of the usual problems that these amps are prone to-bad solder joints on the tube board where the phase inverter resistors are located, a bad R97 resistor (these get hot), or a problem in the +/-16v supply for the solid state devices  that this amp has some of. Also on the list of possibilities were the usual bad solder joints, dodgy filter capacitors and so on.

After some initial testing I discovered that although the bias supply was appropriate for the pair of power tubes this amp had on board, the bias voltage could not be adjusted. That led to  having to remove the main board again, installing a new 25k bias potentiometer (R82) and ultimately replacing the tube board with another.

Great. That problem was cured and it was only then that I found that the channel switching had  disappeared down a rat hole. Since the owner does not use the dirty channel he'd probably never noticed it, all of which led to me dreaming up an amp checkin and evaluation form  so as to evaluate any and all systems on board before disassembly.

The problem manifested itself as the relays started chattering and a lot of noise was being injected into the signal. The system was unusable. Also the dual LED would not light red as it's supposed to when "more drive" is engaged.

After I'd replaced a bunch of small zeners and diodes with no luck I got suspicious of U3, which is a BA4560 dual op amp.  I installed a socket (good thing when removing ICs) and plugged in a 4558 op amp which is said to be equivalent. It quieted the relays but I still did not have the 'more drive' function (which is a couple of FETs).

So back to the drawing board and I ordered all the small parts I didn't have including some real BA4560s. They arrived today and plugging in a genuine BA4560 cured the problem. I think I'm home free on this one.

Points of information. I'd been informed by someone else that had this same problem that installing  a pair of new diodes D26 and D28 cured the problem for him, but the entire episode leads me to believe that if any of the small solid state components in the switching system fails you're likely to run into the same problem.

Best guess? They're cheap, so take the schematic and buy a few of everything you will need to 'cut and paste' your way through this problem.

And beware of "equivalent part numbers."

In the schematic I've marked out the different areas of the switching circuit. 1 is the +16/-16v power supply, 2 is the the switching circuitry including U3, 3 is the 820 ohm 2w resistor R97 and 4 is the more drive FETs.

Uncomplicating a jack swap on a Blues Junior

Every time someone asks me to get rid of one of those cheesy plastic input jacks on a Fender Blues Junior-or for that matter a Blues Deluxe, Hot Rod Deluxe, Devilles, Pro Juniors or any number of miscellaneous amps I always forget how it's done and have to go looking it up and wade through the dumpster that is the internet for that ".........OK. I remember now" moment.

The reason Fender uses them is simple-machine stuffing of circuit boards.

So here's a simplified drawing that will take you through it and remind me next time when I change the jack on my Pro Junior-which is a fun smallish amp.

We're looking at a 12A Switchcraft grounding jack, and two insulating washers from Mouser Electronics, a flat one and a stepped one. They insulate the jack from the chassis that way there aren't going to be any ground loops.

As always, check yourself and also me, make sure your amp is unplugged and the filter capacitors properly discharged. A test lead with an inline 100 ohm resistor will do fine for this chore. If you think it is beyond your range of normal competence, for crying out loud take it to a professional. There are three of us in the Des Moines area and all of us will serve you well.

For all that, 2016 was not a bad year overall, of course not mentioning politics. I dunno, the combination of social media, mass idiocy, and aggro rhetoric produced a perfect storm of sewage delivered right into my home that has left me cold. Some of the things I've seen people who claim to be adults give voice to were just that-liquid excrement. I've no interest in repeating the experience and I have terminated my association with them.

Racism and hatred has no place with me. Aside from being generally wrong, it takes up too much time that could be spent making music or helping others to make music.

I'm going to see what I can do to make my party more relevant, but in the meantime I shall stay close to the things I like to do and see and think about and let the other shit slide, along with the people who bought into it.

I think in 2017 a lot of people are going to find out they've been bamboozled and hornswoggled. Just my opinion, your mileage may vary.