1956 Voice of Music8 watt amplifier

This was a fun one. 1956 (or so) Voice of Music 8 watt amplifier. I like that it's just called "8 Watt Amplifier". No fancy school names, nothing clever to shift more units of these babies!



Complaint was it's dead! Lights on but nobody home. That's a good thing. Always easier to fix a dead amp than one with annoying intermittent problems. In this case all those beautiful Mica Mold capacitors were just plain dead. I also replaced the filter caps and added a cap to the 300 ohm cathode resistor on the 6v6 output tubes. This helps low end response while also helping tame some hum away. So it ain't on the schematic. Who cares? Let's improve it!

Super cool slide out chassis:




10" Jensen Alnico 5 speaker! Worth the price of admission.




Some shots of the not 'mil spec' bowl o' spaghetti design:



Mica Mold Capacitors! I'd love to hear a fresh set, never have. They're almost always leaky. One read a whopping 114 vdc on the potentiometer side!



But either way, they sure are pretty. I replaced them with a set of Mojo Dijon for the preamp, and Sprague 225P polyester Orange Drop caps for the phase inverter. An amp like this can benefit from that setup, very clear and warm, but not mushy.



Shot of the filter cap. I upgraded the 470ohm 3 watt resistor with a 500 ohm 5 watt. Also used 2 watters for the 10k power resistors. I like to never see an amp again once it leaves so why not?



Cap dated 47th week of 1956!




Schematic included! I love that. No guesswork if something is burnt.





I love the speaker connectors.




How does it sound? Perfect for what I like. It's not your Neil Young rage box, it's subtle and sweet. Very open and clear sounding. This was never intended for guitar, it's a PA amp. It's the kind of thing I'd use in my living room while someone is playing a big Gibson J45 or  Martin D-18. It gets only slightly louder than one of those at full strum. Perfect accompaniment amp.

Single 5Y3, pair of 6V6 tubes driven by a 12AX7 and a 12AY7. Same tube compliment as a Tweed Deluxe but completely different sound due to a completely different circuit. So if you like something fresh and unusual, seek one out! This is a lovely amp to look at as well as play. And I like nice looking things in my living room. 

-J

1955 Fender 3x10" Bandmaster, 5E7. Yes, rare as can be.

This was a fun project. A 1955 Fender Bandmaster with 3 10" Jensen P10R speakers. This is the first original one I've had the pleasure of playing, I built one when I had my shop in Portland and sold it soon after. If I ever need to go 'big' again, I may build another one of these for myself, this may be the candidate for what I need.

What do I like about these? They are raw and primitive. They are part of the evolution to the more refined legendary Bassman amp. They don't work nearly as well in other words. The tone controls are a bit weird and the transformer to speakers is a good mismatch! (4 ohm transformer into a 2.6 ohm load!) That's a part of the sound for better or worse. Plus, I love the size. A Bassman is just a bit too big for any of my needs.

Speaking of that mismatch, you almost never find one with the original output transformer. They simply burned out. A friend had an even more rare Brown 3x10" from the early 60's and that had it's transformer replaced just like this one. I believe only Mercury Magnetics makes a proper 2.6 ohm transformer for these. When I built one that's what I used. Great part but I was a little let down. It was a lot more iron than I expected. I think they call it the "Fat Stack" or something like that. I prefer to have a smaller part, I don't need all that clear bass! So hopefully someone out there makes a trashier part now. A great sounding amp is a mixture of excellent quality parts and frankly, crap. Too much of either direction and you lose me.

This amp belonged at one point to a rhythm guitarist who played with Muddy Waters. When it came to me I saw pictures or the insides and outsides. I could see it had Orange Drop Sprague capacitors throughout, not my favorite, and the work looked a bit sloppy.

It also had a solid state rectifier and just okay modern tubes:

Once I played it other than a bad distortion (one of the speakers had a bad voice coil) I had to wonder what could I do to improve it besides the obvious: better tubes and a proper tube rectifier.

Once I opened it I could see the Orange Drop caps weren't the icky 715 type, but old polyester. I like those. They are nice and warm. You can identify them by the black stripe on the outside foil side:

Notice the blue resistors and the 2 "Chocolate Drop" capacitors in the preamp. Those do have to go. Not acceptable parts in a Cadillac!

Those blue metal film resistors are ok for load resistors, in fact they work better and are more stable. But stable isn't what were after here, we want that extra push over the cliff into special!

The only drag with modern Carbon Composition resistors is they seldom have long enough leads. So I had to extend the 2 watt cathode follower resistor:

Tone stack complete:

I use Mojo Dijon caps as these are my favorites. I also opted for a 250pf 500V silver mica cap for the treble cap. For the phase inverter I left the Orange Drop caps intact. I like them there. The Mojo caps are more like an old cap. Nice soft edges, warm. Mixed with the polyester Orange Drops I think it's a good balance.

Next was the tone caps on the pots themselves:

These were really poorly soldered. In fact the one on the treble pot simply came off then I touched it with a chop stick! You really need to have a high quality iron to get that joint right. Don't cheap out with your economy iron! Buy a Weller already!!! Also hit the back of the pot with sandpaper and use rosin. You'll have a much easier time of it and some pots you simply can't solder on to the back without sanding or using a scratch awl!

The caps themselves here don't matter as much, they are only bleeding some signal to ground, but I replaced them anyway cause, why not? The Mojos look more like the original Astron caps so....

Now the switches. They were fine, just not a classy part in my opinion. I can't stand seeing some big ass disco switches on one of these amps. It just looks stupid!

The one on the right is the replacement. I'll use the old ones for a Plexi, which likes the big bats!

Also on the standby switch I needed to add a .047@600V cap to ground. Not entirely necessary but it's in the schematic so:

And if you notice in the above photo the original wire had oxidized badly. I needed to replace that length with some nice cloth stuff as well. If I wanted to be all picky I'd age the wire with coffee, but who is going to see it???

Then the bias circuit and the grid stop resistors. I did add a trim pot to adjust bias:

Next the sexy part... The tubes. These amps sell for a lot of dough. Sovteks are nice, and I do like the Chinese 12AX7 tubes it was loaded with but, let's reach for the top shelf. Sovtek 5881 tubes replaced with Tung Sol made RCA!

Also that blasphemous solid state rectifier replaced with a NOS Sylvania 5U4 made the same year as me, 1968:

Those scuzzy preamp tubes are replaced with Mullard made "Phillips" branded tubes. And the first gain stage replaced with an RCA 5751. A bit less gain but that's what Fender wanted. Want faster breakup? Use a 12AX7, or....just turn the volume knob up!

Photos of the transformers:

The power transformer and choke are original. The output is from 1961. It's a proper Schumacher Bandmaster transformer.

And a nice chassis shot:

I did use a bigger (30uf @ 500V) cap in the first stage of the power supply. Personal preference. The rest are proper 16uf and an 8uf for the preamp.

So how did it turn out? Was all this work worth it? The amp did sound great but yes, it sounds better now. That extra color to the tone, and it's a more defined. Warmer. So I say yeah, it was worth it!

So if you own one of these, you know how lovely they are. One of the most unique American made amps that ever was produced. It's unusual cause Fender knew how to build an amp like no other, so why the mis match with the transformer. As the drive to produce cleaner tones and more powerful amps to achieve this ensued, I wonder what he was thinking with this one?

For those of you who don't have the dough for an original, I see Fender is making them again. They are pricey but not as pricey. My opinion? Pay someone else like myself or maybe Victoria to build you one. We'll do you better!

-JB

'59 Bassman Reissue

One of the most sought after amplifiers in the world is the Fender tweed Bassman produced from about 1958-1960. There is a good reason for that. It really is a Swiss Army Knife that can handle just about any gig with the exception of metal, but even Eddie Van Halen enjoyed one of these. Trouble is to find an original you need a bankroll like fast Eddie, they can command prices upwards of $10K in great condition. I remember the first one I ever tried, that was at Mr C's Music in Marlboro, Massachusetts. My dear friend Shawn Clement's pop owned it (remember mom and pop music stores?). It was an ugly example and this would be in 1986. The tweed was removed and the pine box had a walnut stain to it. This was the days before people started re-tweeding, relic weirdness etc. You simply played the things and made them better looking in your eyes. I thought is was really cool looking actually and when I played it, though it had no 'overdrive' channel or reverb, the sound I could produce with my 18 year old fingers got me curious about old amps. It was around the next year (1987) that I went to the NAMM show with the Clement family and Fender introduced the '59 Bassman Re-issue. I'm a lifelong Fender fanatic so this totally caught my eye.

Todays example is one from right around that era. It has the blue Eminence speakers rather than the trashy sounding Jensen Re-issues. True story, I had a totally stock Re-issue Bassman from this era and a Victoria version (all hand wired, very nice amp!) that had my least favorite caps and speakers, the Jensens and those 715P orange drops. I had a bunch of my customers play them and they all preferred the re-issue. When I told them it was just an $800 stock re-issue amp, none of my customers believed me. So yeah, these are really good amps.

This particular one was making no sound at all. Dead. That part of the problem was easy to solve: one of the speakers, which are wired in parallel had shorted out. Zero ohms. Unusual. In 25 years I have maybe seen this once, and that could be my memory inventing stories. So I replaced it with an Eminence alnico. Same great speaker as far as I can tell, and I'm a fan of Eminence speakers in general.

Control panel. Yes, those of you who know amps already know this. This is the amp Jim Marshall copied when he made the even prettier Marshall amplifier. Circuit is nearly identical, layout is nearly the same and they are both lovely amps. Those of you who may find that morally objectionable, nothing is original. Fender merely copied old Western Electric and RCA circuits and elaborated on them. That is the fun of tube amps. Copy then experiment!

This amp was also modded, or, hand-wired. Not the tidiest job but still well done:

I've done these before. I prefer to go the old fiberboard route. More room for cooler capacitors. Curiously these are the same caps that Fender uses in there modern amps. Why go to all the trouble if you're not going to do something different. Still, this is an improvement and the person who owns it is selling it. The next buyer is getting something that would sell for a lot more if it were 'boutique'.

This part I didn't like:

Very well done but no cover for the filter caps. Not that anyone will be reaching up there during a gig while it's on but, man, this is dangerous. Also the 2 main filters are 220@350v in series giving you 110uf. With a tube rectifier you really don't want to go above 50. It can cause a drain on that tube and on the 5V filament winding. Or at least this is what the old RCA manuals say and I trust them.

Using such a large filter in your first stage gives you the benefit of improved low end and overall more headroom, plus it's quiet. However, most folks like a little sag and compression. I changed them to 100uf each giving me 50 total. Hum? Nope. Very quiet.

Also had one noisy preamp tube and after a cleaning and tightening every bolt (many were really loose! Output transformer was barely hanging on!) then it was a wrap! Great sounding amp. If I ever decided to go big againit would either be one of these or a Vox AC30 or a Marshall Bluesbreaker. Either re-issue amps so I can actually play them live without worry or I'll build one myself. I had the honor of re-building Jimmy Vivino's Bassman Re-issue years ago and I heard it became a favorite of his. Allegedly Slash rocked it and fell in love too. That amp I simply took out some funky mods and re-tubed it. These are great amps. If you can find an early one like this even better. If you can pay me or someone else you trust to hand wire it then you have something that is really just as good as a $10,000 original! Why pay more?

J