[chrono]

Hi guys,
 
I have this KT-88 Tube amp which I purchased off of eBay about 4 or 5 years ago. It's a hi-fi system amp, no headphone jack. I got it from the manufacturer in China, and it has no branding on it. The only markings say "TM300" and "Hi-Fi Valve Amplifier". It does sound quite good.
 
I lost the specs from the eBay auction, and the seller is now gone. I am having a very difficult time finding any information for this amp.. anywhere. I know you guys are probably the most knowledgeable when it comes to audio gear, so just thought I'd ask and see if anyone knows anything about it.
 
Thanks, I do appreciate it. 

 

 

 

[fengz]

I think it's a Mitsutsune tube amplifier.

 

[Sasahara]

That is absolutely gorgeous! How does it sound?

 

[chrono]

Quote:

That is absolutely gorgeous! How does it sound?

Thanks Sasahara. It sounds great, though it is my only tube experience so I don't have a whole lot to compare it to. It really brings music to life, the best way to describe it is that it adds more depth and texture to music which I have not heard in solid state amps. And I have to agree it does look good 

 

 

[chrono]

Quote:

I think it's a Mitsutsune tube amplifier.

I can't find any information on Mitsutsune either unfortunately 

 

[Joeinmtcl]

Hello Chrono,
 
For several months now I have been searching the internet to get info on a tube amp I too purchased in 2007 on ebay from China but with no success until I came across your post and picture. Your amp is EXACATLY the same as mine. When I first came across the ad for this amp on ebay is was being sold by someone called “hotproductstore(354)” and the amp was called a “Richton Audio Tube Amplifier” and the tube compliment was given as (4) - KT88; (2) – 6N7P; (2) – 6J8P; (3) 5Z4P; and (1) – 6E2. The picture in that ad showed the amp with only one display tube in the location of V9. Shortly thereafter the amp was being advertised as a “smart modified version = much better than unmodified version”. The Richton name no longer appeared and no tube compliment was stated. The picture however showed two display tube in positions V5/V6 and that picture is exactly the same as yours. I purchased the amp but ,unfortunately for me, when it arrived it had been badly packaged and several tubes were broken, and there was no documentation supplied. I attempted to work things out with the supplier but to no avail and had to give him a scathing negative review on ebay. To compound my problems the tubes supplied in positions V7, 8, and 9 cannot be identified. I wish I could help you more with your questions but I am afraid I cannot. I hope you can help me with mine: (1) do you know the type of tubes supplied with your amp, especially at positions V7, 8, and 9, (2) do you have any documentation for the amp, and (3) are you interested in selling yours.

 

[rnolan96]

Hey Joeinmtcl
I was given one of these amps today and tripped over this thread looking for some info on it. I worked a few things out just by looking.  I'll crack it open later and check out the circuit to find out a bit more.
 
Inputs: All 3 inputs are line level (CD, Tuner, AUX1),
Outputs: the output posts are for either a 4 ohm speaker load or 8 ohm (the output transformer taps are fed direct to the posts (generally there is a selector switch for this, arguably it's better not to have a switch)
 
The tube compliment in this one is slightly different to what you posted, but I can help you with what goes where and why.
So Tubes:
4P: 3 x 5Z4P - these are the 3 tubes between the transformers, they are rectifier tubes (turn AC into DC), normally there would only be 2 (one per power supply/transformer), why 3 ? smoother power is my guess but how (I need to sus this further).  These days it makes some sense to change to a SS rectifier circuit...
V5 & V6: 2 x 6E2 - these are the "magic eye" thingys, all they do is glow and act as an inaccurate VU meter, but they look cool ? you can probably take them out and have no affect except use less power.
V7 & V8: 2 x 6CG7 - these are twin triode mid/low gain preamp tubes, (so 2 gain stages (triodes) in each tube), one tube per channel. (These (I suspect) do the same job as the 6N7Ps in your post).
V9: 1 x 12AT7 - this is a mid/low gain high current twin triode, they generally make great phase splitters (as high current) in guitar amps. Normally there would be one per channel to split the signal into +ve and -ve for the output tubes in a push pull circuit. So need to sus this out, why only 1 tube ? 12AT7s are also sometimes used as mid/low gain input tubes so it "might" be for the AUX1 input (or all the inputs).
V1 & V3 (L); V2 & V4 (R): 4 x KT88 - these are the output tubes, 2 per channel, so at this point I'm assuming a class B push pull (one tube for +ve, one for -ve), but where's the phase splitters to feed the output tubes ?? Maybe the 2 6CG7s are being used as phase splitters and the 12AT7 is the only input tube (one triode for L, one for R)??
 
I think the 6J8P listed in your post is a furphy ?  it a pentode output tube, fast Piezo amplifier.
 
So hope that helps