1940's Kalamazoo KEA

 Curious little bargain tube amp that I got to bring back from the dead..... a 1940's Kalamazoo KEA.

This is one circuit that I'll admit I have little idea of how it works. It has a single 6SJ7 driving a pair of 6V6 tubes. How this is achieved I do not know. It's not parallel single ended. Look at the schematic!

The other challenge was finding a 10" speaker that is shallow enough to fit in such a tight space. This project sat around and almost made the 'sold for parts as-is' pile. Nothing fit! But fortunately I was able to find an old CTS speaker in the bowels of Southside Guitars deep in the basement under discarded case parts...... It was dead so we had it re-coned. Speaker had the perfect holes to mount the output trasformer.

In the end it's a fantastic little amp. Not a fuzz box, very clear and defined. These are financially not worth the effort, you'll likely lose money doing what I did. But we were all so blown away by it's charming tone that an employee bought it and will be tracking with it! I have an affinity for the 6SJ7 tube. My favorite preamp of all time so it's not surprising how much I like this amp. 

Did the usual, changed the caps etc. Fortunately both transformers were good. I do not think this amp would work well without that odd asymmetrical output transformer. So make sure that part is happy before you commit to one of these. 

J

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

Little Silvertone 1471. 5 watt killer!

Another gem from Indigo Ranch that's been sitting on a shelf since the 90's! This belongs to Sonic Circus as well.




It was totally dead, ripped mouse eaten speaker and all. Found a cool Utah to throw in, re-capped it and it's making music again.

Circuit is similar to your classic tweed Princeton (Champ with a tone control) and it's got a great early Eric Clapton type of sound. Smooth breakup, warm but good bite.. I particularly liked the low end. Smooth and creamy not unlike Billy Gibbons. I just want to play some ZZ Top on this amp.

Simple 6V6 driven by a 12AX7 with a compact 6X4 rectifier.

Here's a funny video of it's first few notes after 30 years of being mothballed.

https://www.youtube.com/watch?v=sumDxmeaeP0



And some photos!











Planet Capacitor, guaranteed for 1 year!!!





So there you have it. These are cheap as chips. Yes, built rather crappy but who cares. Just don't let it get wet as they are made of pressed paper! Fantastic tone. Who says you need a pine box to cut great tracks anyway?

j

1939 Kalamazoo KEH amplifier built by Gibson

Such a cool amp. This came from a good friend of mine. He bought it at a local shop as-is and it was dead.

I love them when they are dead. It's easier to fix a dead amp than one that sort of works. Example is the Oahu amp I bought in Dallas last year at the guitar show for $100. The power switch was dis-connected. Simple fix. The rest is just change caps and resistors as needed.

This was no exception. Dis-connected wire got it going. I had to re-cap it, ground it and change a couple super microphonic 6C5 tubes but that's it.

These early Gibson amps are exceptionally well made. Easier to work on than what they produced from the 1940s on forward. Odd, cause the early ones are service friendly like a Fender. They got worse over time where Fender just kept getting better. I like how you can simply unplug the field coil speaker in these. You just pull the chassis after that and do your thing.

Plus the looks:









This is one beautiful piece of equipment!

Tubes are 3 6C5 preamp tubes, a single 6L6 and an 80 rectifier tube. They do run rather hot. This one showed evidence of the transformers getting hot. I replaced the cathode bias resistor with a bit higher value. Makes things sound a little 'looser' but you know, I'd hate to see the output transformer die in this 80 year old amp.









Tube sockets were labeled right on the socket itself. Classy!


Yup. From the glory days of American manufacturing. These were factory built. Not cheap! You need to pay a builder to get this kind of quality today. Not cheap but come on, you're worth it!

-J

DaVinci 2x12 "High Fidelity" amp built by Magnatone (model 260)

Here's one that was intimidating. A true barn find full of dead bugs and mouse faeces.... effing gross!

It was sold to my friend Dave at Sonic Circus for $50 a few years back. We weren't expecting much since it had spent so much time growing uglier due to neglect.

But once I cleaned it up, re-capped it, fixed the tears in the speakers it came back to life. And it has of course a gorgeous voice! I'm not a fan of the stereo Magnatone amps, too complicated, oddball expensive tubes, but these simpler ones are the bomb. It's about 25 watts with 2 6L6 tubes. Nothing expensive or difficult to find tube wise either. Just a 5u4 rectifier, some 12AX7 tubes and a 12AU7.

These 'stencil' amps built by Magnatone for other companies are a real bargain. Not exactly cheap but not what you pay for one labeled Magnatone. See my other post for the Panoramic amp I still have.

This amp is basically a Magnatone 260. It's now making music again at Sonic Circus. Dave has a beautiful Vox AC-30 with the copper panel. With the pitch shifting vibrato in the amp the 2 seem spiritually connected. Though, I prefer the Magnatone amps myself. Straight up Bo Diddley tone! Less noisy than the AC30 too, though, no diss on Vox. Those are amazing too.









Do notice the Celestion 'Guitar Center' model speaker I threw in. Not a bad choice but fortunately I was able to get the original speaker going again!



Bowl o' spaghetti construction:





And there you go! Get out there and try one of these. They have quite a sound! J

70's Traynor Bass Master. Prog rock EVIL!!!!

This was a fun one. At Sonic Circus they have 3 amazing Ampeg B-15 amps of varying vintage. They have an early cathode bias model, which is out favorite, a later fixed bias from around 1966 and a more powerful 70's one. They all record so nicely.

We were cutting tracks and believe it or not I was getting a bit bored of the B15 Fender Precision bass combo. Some of Dave's material is venturing into Prog territory. He's a great guitar player, his son is a great everything player, so I felt like just kicking back and playing bass, acoustic guitar and some saxophone.

So anyway, I pulled this neglected old Traynor off the shelf. Another fine amp from Indigo Ranch Studios...



It's no B15, that's certain. It's aggressive, nasty, impolite.... sounds like Geddy Lee or John Wetton rather than James Jamerson! All are outstanding bassist. Both inspire me!

Amp is about 50 watts with 2x EL34 tubes and 3 12AX7 tubes. Single 15" speaker. EVIL SOUND!



















Another simple Re-cap, changed the output tubes. Sadly the Mullard RCA stamped tubes were shot.

These are a bargain. Great for guitar as well. Hand wired, Hammond transformers, Mullard Mustard caps in the signal path, and built like a tank. Go get it! You won't regret it!

1978 Traynor YGM3 Guitar Mate from our northern neighbors

Here's a bargain amp. A late 70's Traynor YGM-3 Guitar Mate!

These were built in Canada. I've worked on plenty of Traynor amps before and am quite fond of them. They are built to last and can be had for a cheapish price. Much like Jim Marshall who was motivated by building a cheaper amp than the Fender amps around London, Traynor did the same thing in 1963: let's build local, high quality affordable amps for the new music being made. All in the name of problem solving. All in the name of service. The best stuff is motivated by those 2 very important human things.

This amp is all hand wired just like a boutique amp. My client bought this on Craigslist for $400....

I believe this to be the Canadian response to the Fender Deluxe Reverb. It has a single 12" speaker, tremolo and reverb with a bright switch. The biggest differences are the lack of a power choke, no reverb driver transformer (cheaper to use a capacitor!) and a pair of 6BQ5/EL84 power tubes rather than the American 6V6. The result is it sounds like an English Deluxe Reverb, more chime and accented mids like a Vox.

Hand wired guts:

One of the nice things about working on these old Traynor amps is you don't even need to pull the chassis. You can remove the 4 bolts holding the top on and simply pull the hood off. Then you're ready to get to work! Though I can't help but think of brain surgery....

These amps boast the famous Mullard "Mustard" capacitors. Those are almost always still good so I'm leaving them alone. The amp hummed badly and sounded harsh. I knew right away what was up: bad filter caps and one dead power tube. Turns out one tube was completely dead, the other was very weak.

So a word about the tubes in these. They tend to get eaten alive. The new JJ or Sovtek / Electro Harmonix glass? You may experience shortened tube life. Those tubes are rated for around 300 volts. This amp boast around 420 volts! Luckily my client wanted more headroom so I just ordered some EL84M tubes from Sovtek. They are rated for 500v. They are the modern version of the 7189 tube. More for hi-fi like my old Fisher SA-100. Linear and clean. I find them to be very punchy, strong sounding tubes. They are a bit maligned by the guitar crowd, people prefer the sweeter tone of an EL84 but just keep in mind these are an option.

Cool Russian boxes!

 I re-capped it and added a bias pot. Due to the layout Traynor made the job so easy.... I used a 20K trim pot and changed the 22k bias resistor to a 15K cause the EL84M / 7189 biases a bit differently than a JJ EL84.

I also added a couple 1 ohm resistors from the cathodes (pin 3) of the EL84 tubes to ground. You'll read millivolts there which correspond to milliamps. 25mv=25ma. Easy and convenient:

I hate the bright switch in these. They use a .001 cap. It's like shaking a can of nails by your ear! I replaced that cap with a 100pf NOS silver mica cap. Now it adds a bit of smooth bite:

I ran it tonight with a set of JJ tubes running at 25ma each. I didn't get any red plate stuff but don't really trust them to last. The amp sounds great now. No hum at all unless you add that beautifully lush but humtastic reverb.

So if you want boutique quality at a crappy new amp price, don't turn your nose up to one of these. They can truly hold their own with the best of them. I actually like the rather mod styling too. Fender, Marshall and Ampeg went full industrial unattractive by this era. But these Traynor amps still have a touch of class. They look nice, and looks matter to me. If you buy one do keep in mind you'll want to get it checked out and possibly set it up with the beefier tubes. Unless you don't mind burning them up that is.

JB

Silvertone 1434 2x12" combo. Tedious to work on but well worth the effort!

Don't have any proper photos of this one as I only have the chassis to work on. Decided to leave the cabinet elsewhere. It's a big amp and I have little room!

I've worked on many of these. I quite like the sound of them. Big and trashy!

They are a bit tedious to work on. One needs the proper approach to get them right. In this case the amp didn't work at all. That part was easy (6EU7 tube in place of what should be a 12AX7!). The rest isn't difficult at all, you just need to be patient and re-cap the thing.

When I say re-cap I usually mean change those dried up electrolytic capacitors. That part is obvious and on one of these amps quite easy. But for these amps you'll need to change EVERY CAPACITOR along with every load resistor. They are noisy. Every Sanagamo cap was leaking or dead. The tremolo was completely dead. That entailed replacing an open 330k resistor along with all the tremolo circuit caps. Also need to replace the load resistors. The 6AU6 tube was good, they usually are.

Tremolo circuit:

The 330k 'feed' resistor I'll be replacing with a 25k trim pot. Once I got the tremolo to work it was simply weak. I reduced that resistor to 50k and it's way better, but it can be great so let's go for that.

More shots inside the chassis:

Phase inverter/driver circuit:

One of the peculiarities of these amps is the filament arrangement for the 12AX7 tubes. Those are D.C. and powered from the cathode resistor on the 6L6 power tubes. They are wired in series with about 28 volts going across both tubes. The nice part about this was I have 2 modern Tung Sol 12AX7 tubes that hummed under any normal arrangement. I couldn't sell them. But in this amp with the DC filaments they run nice and quiet.

Bloody modern tubes! Got a set of modern Tung Sol 5881 tubes I dropped in this amp. One is bad....

I couldn't find a schematic so here is one that has some similarities:

Tremolo circuit is 90% identical along with the preamp....

Amp runs pretty quiet now. These will never be as quiet as a good Fender but don't let that stop you from considering one. If you get one don't bother trying to trouble shoot the issues, just bank on spending a few hours replacing every cap and every load resistor in the house. No sense in playing whack a mole with your valuable time! And please don't buy into that "but the original sound" bullshit! You can buy carbon composition resistors all over the place now thankfully, and I like those Mojo Dijon capacitors for my signal path. Get in there, get your hands dirty and get it right! Worth the effort!

I can say the same with every other Silvertone amp I've worked on. They were pretty crappy amps to begin with but that is their charm. They used the cheapest parts available so 55 years later......

JB

Oliver B120

Ok. I stole this photo. It's not mine. I neglected to shoot this amp when I had the chance.

These are uncommon. Very good studio bass amp. About 50 watts with 2 6EU7 tubes and a pair of 6L6 tubes. It was noisy and weak. Solution was change the power tubes which were shot, re-bias it and replace the main filter can which had burst. I replaced it with 2x 220@350V caps in series for a total of 110uf @ 700v. Added bleeder resistors across them as well.

Also grounded it and removed the 'death cap'. My customer doesn't enjoy getting shocked and nor should she!!!

This one belongs to 75 dollar bill as well! Do check them out! One of my favorite bands in Brooklyn, or this world for that matter! I love me a band that can get a big sound with little tube amps. They are that band. Hypnotic, dreamy, driving, wild and never too freaking loud that you can't sail with them!

https://75dollarbill.bandcamp.com/
Click here^^^^^^^^
Thank you! JB