Wednesday, October 14, 2020
Sunday, October 11, 2020
My 5E3 Deluxe "UN"-clone, simple mod for tight bass, more clarity. (As featured on 'The Truth about Vintage Amps with Skip Simmons"
So, obviously that's not true. But there isn't much to it. First, a bit of background. I have no qualms with the stock 5E3. I'm a big fan of Neil Young and his sound and I've always liked the 5E3. I just wanted to build something a tad bit more modern for my own use. I prefer a tighter sound, something that is more clear. Most of my gigs I'm not using a mic. I've had little tube amps literally get swallowed up into the mix. I can't actually use that. I need to hear myself to have a good time.
The first thing I did was what I usually do: 47uf capacitor on the first stage, followed by a 22uf then an 8uf. That 47uf makes a difference in sag and compression. The original is 16uf. I also like that first stage to clean up any unwanted 60 cycle hum right off the bat.
The second thing I did was use a larger cathode bypass capacitor across the 250 ohm 10 watt resistor. You can experiment with values there, I used 100uf @100V. The Vox AC30 uses a 250uf cap there. Deep bass.
Photos of power supply and cathode bias arrangement.
Wednesday, September 16, 2020
Curious little bargain tube amp that I got to bring back from the dead..... a 1940's Kalamazoo KEA.
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.
I thought I'd share about this one.... very rare bird indeed. A Fender Model 26 "Woody" circa 1947.
This came through Southside Guitars with the matching lapsteel. Unfortunately both transformers were destroyed. The good thing is I managed to buy some period correct NOS iron that worked perfectly. I don't think one needs to be too precious in what iron one uses as I believe Fender used what was available in these early days. I could be wrong about that but either way the amp turned out to be fantastic sounding.
I needed to replace every capacitor in the house and some resistors. Curiously rather than using a 250 ohm 5 or 10 watt resistor for the cathode bias circuit, Leo used 2 500 2 watt ohm resistors going from pin 8 to ground with a wire connecting the two with a single 25@25 volt cap on the board. I replaced those with some pretty NOS 500 ohm 5 watt wire wound resistors.
The speaker was shot but original so I had it re-coned. Always the best choice I feel, especially with these. There is no place to mount the output transformer except on the speaker. Worked out nicely!
One peculiarity with this amp is the tone control. It's the worst I've ever seen. It's a 2 meg pot and a .05 capacitor going across the anodes of the 6V6 tubes. Oh, it worked, very dark, turn the pot then like a switch it's full on. That goofy taper doesn't actually bug me but what does is when you blast the amp you can see sparks inside the pot! I asked the owner if I can wire it somewhere else in the circuit, like a normal tone control. Better to not have an amp flame up. It's fine at moderate volume but who wants that with a little scream box like this????
I can say this amp sounds incredible. Very colorful, very rich and quite loud. More "primitive" than a later Deluxe and has a focused sound with that 10" Jensen speaker.
One that is worth building if you are into that sort of thing. Experiment with that tone control I say!
Wednesday, April 3, 2019
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.
I had the honor to work on this old Vibroverb last month. At first glance I thought is was a reissue model cause it's so clean. I looked at it again and said "No way!" thinking it must be a kit. Then I realized I know the owner and he has pretty fine stuff.
I've never seen one in person. This goes on my bucket list of rare Fender amps like the 3x10" tweed Bandmaster here.
Amp was blowing fuses. The filter caps were bubbling so I replaced them but unfortunately the problem was the reverb driver transformer was shorted. BUMMER! Nobody makes quite the same part so I just used a new Heyboer with a large washer to hold one end on. No holes needed to be drilled this way and no one is ever going to see it anyway. Easy fix.
The original part goes into a plastic sandwich bag so the owner can decide what to do with it. Paperweight or get it re-wound? He doesn't care since he doesn't use reverb anyway.
Amp sounds amazing. First model to sport those 'brick drop' caps like you see in late 60's models.
Did I mention this amp sounds amazing? I'd go so far as to say aggressive. If cost were no object....
Original speakers. At some point they were wired backwards! I've seen this many times....
Original milk chocolate footswitch. Mmmmmmm.....