1965 Kay 720
"KayBreaker"
For the last few years I have been on a quest for nostalgia's sake to reacquire some of the gear I used when I first started playing all those years ago. I now have a Silvertone 1482 and a Lafayette fuzztone like I used when I was 15, and am searching for an Epiphone ET-270, which was my first electric guitar. Here is an amp I never owned, but played through, a Kay 720.

Around 1970 I was playing in a teenaged trio with my friends Tony and Bob, my first band actually, with me on guitar, Tony on drums and Bob on bass. I used the Silvertone and Bob had a Kay 720. I was about a 20 watt amp with a 15 inch speaker, originally designed as a bass amp. Eventually Bob got a bigger amp, I think it was a crappy Montgomery Wards, and he let me use the Kay because the Silvertone wouldn't cut it next to the bigger MW amp. I remember I loved it because it would distort like crazy, especially with the fuzz box.

I got this one off Ebay last year for around $200. When I fired it up it sounded pretty bad. I received two speakers with the amp: The original Oxford speaker which was blown, and an Eminence speaker mounted in it that didn't sound too good either. The power tubes didn't match and all the tubes were worn. I proceeded to restore it and lucky for me my friend Jeff Andrews had a similar one in for repair at his shop. He fixed it and did some mods to bring it into the new century, making it more guitar friendly. He shared the mods with me to use on my Kay, pretty simple ones really, but they helped bring the amp alive and make it very useable. Special thanks to Jeff Andrews for the help on this one!

I also did some things on my own. The amp design is of the kind that has a top panel with the inputs and switches and knobs that cable down to the amplifier itself. This can be prone to hum and so on if you're not careful and when I got the amp the cables were just hanging down, power cords mixing with signal cords. I rewired and rerouted all the cables, installed a grounded power cord, and installed new speaker wire.

Originally the amp had three inputs going through 100k resistors, I changed it to a single input with the traditional 68k/1 meg Fender style setup. I used one of the other input jack holes for a variable bright switch with 120pf and a 47pf caps hooked to a three way rotary switch: 120pf, 47pf, or off. I plugged the remaining hole with an automobile upholstery plug I painted gold.

The amp chassis is just a "U" shaped piece of metal mounted on to blocks of wood, so I put down strips of aluminum duct tape for extra shielding. The chassis makes contact with it when installed.

The original back had holes cut in it but they were covered with grill cloth. This amp runs pretty hot, so for ventilation I had Martin cut me a new back with a hole in it and I covered it with some grill cloth I had left over from another project. It's not identical to the original cloth but pretty close. I installed a jackplate and rewired the speaker outs to it so I can run the amp through an attenuator if need be. It's only a 20 watt amp but it gets pretty loud. An added advantage of the jackplate is that I can use the amp to drive another speaker, or use another amp to drive the speaker inside.

This amp uses a 5879 preamp tube, a 7199 driver tube, a 5U4 rectifier tube, and cathode biased 6L6's. The 5879's are only available as NOS or used, no one makes them brand new. Sovtek makes a 7199, but Jeff says they sound like crap. I bought via the Internet several of each: NOS RCA's, and out of five 5879's, three of them were prone to microphonics and one of the 7199's I bought fried the second week I installed it and took a pair of KT66's with it. I skeptically bought some of those "Tube Damper" rings off Ebay to alleviate the microphonics and dang if they didn't help. The amp has been working fine for several months now. Right now I am running a pair of Sylvania 6L6GC's I had in my tube collection and they sound quite good. I have also ran JJ 6L6's and 5881's that sound pretty good.

The final thing I did was purchase an Eminence Big Ben speaker from Jeff and install it, it sounds very good.

The cabinet is a little rough, after all the amp is 41 years old. The covering is little more than wallpaper!!

I love this amp!! The tone is just terrific! It's probably my favorite of all my collection right now. It has a very unique, warm smooth tone. You can get a spanky clean tone from 1 to around halfway on the volume control, and if you dime it you get awesome growly Bluesbreaker type of distortion, especially with humbuckers. It's a great blues amp, in fact I've taken it several times to a local blues jam and it sounded wonderful. Hence my nickname, Kaybreaker. It sounds great with my Strat or my Les Paul. If you dime it you don't need any pedals, trust me, but if you dial it down a little I've found a pedal like a Bad Monkey or Tube Screamer will push it into high gain. That makes it more versatile because you can get clean and distorted sounds by working the volume control on your guitar and using the pedal.

More pics below, check them out. 

Mods list:
  • NOS RCA 7199 and 5879
  • Sylvania 6L6GC's
  • Sovtek 5U4GB
  • Toothpick in the hole trick to fix loose screw holes.
  • Jeff Andrews mods
  • Disconnect two of the three input jacks
  • Change remaining input jack to shorting jack with 68k/1meg input resistors
  • New 16g power switch, AC, and heater wire
  • New 16g speaker wire
  • Repaired cab, new screws, speed nuts, etc
  • New 16g grounded AC cord
  • Remove .05 death cap
  • Metal duct tape shielding
  • 2 way bright switch: 120pf, 47pf
  • Jackplate for attenuator insert
  • Original speaker: Oxford 15L6N-6 465-552 from April 1965 replaced with new Eminence Big Ben

Here you can see the input panel with the variable bright switch. That was a good idea, it gives me choices when I switch from the Strat to the Les Paul.
That's a vintage knob I got off another old amp I had laying around.
Here is the amp itself. You can see the tube dampers around the 7199 and 5879. They actually work to prevent microphonics, which surprised me.
Here is the rear with the back removed. You can see how I routed the wires and attached them to the cabinet. Originally they were just hanging all over. If you look to the right you can see the schematic pasted in the wall of the cabinet. That's nice, but I'm glad I found one online!!
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