Knight mono tube amplifier mystery

A

Aage

Super Member
Hello, all. I have finally started cleaning up and selling a lot of the old stuff I have dragged around for something like the last 30 years, and I came across a perhaps silly question, since I have a feeling that the answer is going to be very simple.

On this amplifier, can anyone tell me how the top cage comes off? I don't want to get too rough with it, but for the life of me, I don't see where it separates from the chassis!

Here are a couple of pictures of it. It's quite a cute little amp, only a little bit taller than a can of Coke.

I think it was a kit. I took the bottom plate off to see if that would give me a hint on cage removal (which it didn't) and the wiring looks hand-done to me. Well-done, but certainly not on an assembly line...

ps: does anyone have an idea of the model number? I'm guessing that it's under the cage, along with the serial number.

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Can you split the chrome band where the seam is? Try using a plastic tool of some sort to keep from scratching anything.
 
Some amp makers had the top attached with "friction" or "ball and socket" catches, meaning that a good sturdy tug on the cage would have it come free to reveal the goodies underneath. The caveat is if the amp has been around since Christ was a cowboy this exercise might actually prove to be challenging, as corrosion can make an indeed convincing bond of metal-to-metal. AMHIK.

Other makers were more rectumnal, and one might have to drop the bottom to access screws inside that hold the cage from underneath.

Look and proceed carefully; some manufacturers could be very "cute" indeed in their practices....
 
Take off the bottom plate. Check for screw between the volume and base control for one side; the other side near the input of the power cord.
 
reggaenaut said:
Take off the bottom plate. Check for screw between the volume and base control for one side; the other side near the input of the power cord.
Click to expand...

That amp is a Allied Radio Knight-Kit KM-15 and older versions went by the stock number in the Allied catalog. It is about 12 watts. I have had about 6 of them. The plate resistors, I think 220K ohms are often open or have gone way up in value. Also, the filter capacitor is often very leaky and should be replaced. I did have on of these that smoked the power transformer.

The top is held on by two small screws as noted above. Take the bottom off first...
 
BTW, those two controls on the side near the inputs are not part of the original kit. They were added by someone. You may want to take a picture of the underside. I have the assembly manual and schematic of this amp.
 
kvflyer said:
BTW, those two controls on the side near the inputs are not part of the original kit.
Click to expand...

I was wondering about those controls since they are not on mine.

I had forgotten that I had this amp until I saw this thread. After a quick search I found not only it but also a Dyna tube tuner and a 6L6 tube mono power amp.
 
reggaenaut said:
I was wondering about those controls since they are not on mine.

I had forgotten that I had this amp until I saw this thread. After a quick search I found not only it but also a Dyna tube tuner and a 6L6 tube mono power amp.
Click to expand...

See there, that's why we never get rid of stuff. It's fun as hell to find it every few years.:thmbsp:
 
Thanks very much to all of you, the screws were indeed under the bottom plate, and they did allow the cover to come off. More pics "under the hood" for your pleasure.

In two of the pics, I try to show the add-on pots. Perhaps bias pots for the outputs?

Didn't really have time to look hard at it, off to celebrate xmas with our Snowbird relations who leave for FLA soon. I will follow up later.

Tom, thanks for the link you posted, it had it in there, a 12W (EL84 outputs).

IMG_0671.jpg

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I love it! I've been toying with the idea of building a pair of EL84 monoblocks to use an extra set of output transformers I have laying about.

It's a shame yours has such low quality stock output tubes in it. Mail them to me immediately for proper disposal, if you don't mind. I'll even reimburse you the shipping cost. :yes:
 
Yes, they are nice amplifiers. As I said, I have had about 6 of them over the years. Very easy to get going. Depending on the manufacturer, those plate resistors on the 12AX7 tubes are often open or way high in value. Not only with this amp but the little 20-watt amp that uses four triode/pentode tubes in a row along the back. Those buggers have a huge filter that is mostly bad.
 
kvflyer said:
BTW, those two controls on the side near the inputs are not part of the original kit. They were added by someone. You may want to take a picture of the underside. I have the assembly manual and schematic of this amp.
Click to expand...

Any chance I could get a copy of the schematic?
 
Hey! I have one of those! Mine was crammed with Mullard tubes too!

The earlier poster who said to take the bottom plate off, and unscrew the cage from there was correct.

Before I can play with mine much more, it's going to need a new set of power supply caps.
 
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