Knight KM-15 amplifier

[electra225]

I have had this little mono amp forever. It was my stepdad's and I got it when he passed in 1987. He used it as a bench amp. There is nothing special about it, outside of the fact that it is populated with high-end tubes that are worth far more than it is. It has a PACO-branded Mullard sourced 6CA4 rectifier, one Mullard 12AX7 and one Magnavox-branded, RCA-sourced 12AX7, then a push-pull pair of Mullard EL84, 6BQ5 audio output tubes. It pulls 38 watts in full flight, has a factory fuse in the primary circuit of the power transformer. I recapped the chassis with the exception of the filter caps. I'll leave them like they are for the time being. I'll get some pictures and get them posted.

[TC Chris]

I've got one of those. Pretty sure I built it from a kit. I built a Heathkit mono AM-FM tuner to go with it, both of them in service at my Dad's office for background music. It was replace eventually by a Technics low-end solid-state receiver after staff reported a burning smell. Likely the filter caps shorted. I figured that the power xfrmr was dead so it was relegated to the someday shelf. Since then I've wondered if maybe they got it turned off n time and the iron is still OK.

Chris Campbell

[William]

There is only one way to find out, Chris.

Bill

[electra225]

I have no idea where Sam got this amp. He may have kit-built it. The iron on it is miniscule in comparison to bigger amps. I don't know if the fuse is in all of them or if Sam put the fuse in later. I doubt it, though. That would have cost money. Sam was the second tightest person I ever knew. I can see where it wouldn't take much to take out a PT without some protection. Somebody before me scratched the tube types with an awl and put a 6X4 for the rectifier. The socket is nine-pin, a 6X4 is seven pin.

[electra225]

I dug this little amp out this afternoon and used it to play 45's. The speaker I used was an 8" parts speaker, just connected with test leads, laying on the bench. I need to rig up a good mono speaker setup. I fed my little RCA 45 player into the phono input. It sounded horrible, tinny, distorted. I connected the changer to the tape input. There it sounded great. The phono input must be for a low-level magnetic mono cartridge, such as the GE VR series. The ceramic cartridge in the RCA player overloaded the amp. I played 45's for a couple of hours. The little amp pulls 38 watts. I believe it would sound really nice with a good speaker. I took pictures that I will get loaded and on here for you guys.

[TC Chris]

My best memory of good mono sound was from Lucky's Record Shop when I was a kid, a place where they would give you a listen to records. At the counter they had a manual turntable with a long arm behind Plexiglas to keep customer fingers away, and a big speaker of some sort facing out under the counter. I have no idea what the amp was. But when they cued up the record, there was a satisfying thump when the stylus caught the lead-in groove, and what I recall as uncolored, accurate sound in the very large room.

Try a nice coaxial speaker in as big an 'infinite baffle" (not sealed up) box as your shop allows.

Chris Campbell