Hello
As you can see, this Luxman amp do not use a preamp, the power amp do have a high gain and the tone control are in the feedback with a switch to bypass that tone control
Do adding a buffer circuit at the input would be a good idea and how about using the Pass B1 as a buffer for this amp ?
Is there any improvements that can be done in that amp circuit ?
Thank you
Bye
Gaetan
As you can see, this Luxman amp do not use a preamp, the power amp do have a high gain and the tone control are in the feedback with a switch to bypass that tone control
Do adding a buffer circuit at the input would be a good idea and how about using the Pass B1 as a buffer for this amp ?
Is there any improvements that can be done in that amp circuit ?
Thank you
Bye
Gaetan
Attachments
I would just replace the bias pot and electrolytics. Check the 0.22R emitter resistors,
and output 10R Zobel resistor also. Don't change C121.
If you don't want tone controls, those can be easily removed from the feedback loop.
The input impedance is 50k, so no real need for a buffer.
and output 10R Zobel resistor also. Don't change C121.
If you don't want tone controls, those can be easily removed from the feedback loop.
The input impedance is 50k, so no real need for a buffer.
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Luxman was not the only one to put tone control in feedback.
I had Nikko and Sanyo with the same arrangement. When i measured distortion with cone controls in the middle and bypassed, i got the same figure.
I had Nikko and Sanyo with the same arrangement. When i measured distortion with cone controls in the middle and bypassed, i got the same figure.
My two cents:
- Replace R 8.2K with CCS for LTP
- Add bypass caps (100-220UF) to each supply rails
- network feedback for tone control - replace with new higher quality caps.
- replace all aged electro caps. esp C input
Why change a classic amp from the early 1970’s - and especially something as iconic as a Luxman?
I’d simply recap the electrolytics, make sure as mentioned above that the Zobel etc are all of, but other than that, leave well alone.
There are hundreds of designs here in diyAudio that you could build if you wanted better performance. The value of your amp is that it’s a piece of Japanese hifi history.
🙂
I’d simply recap the electrolytics, make sure as mentioned above that the Zobel etc are all of, but other than that, leave well alone.
There are hundreds of designs here in diyAudio that you could build if you wanted better performance. The value of your amp is that it’s a piece of Japanese hifi history.
🙂