Hello everyone,
I own a few years an amplifier McIntosh MA 6500. It 'a class AB amplifier in which I love for its powerful sound that it produces no listening fatigue. For some time I own a Musical Fidelity X-A1 that I use in a second plant: I must say though that sounds better than the McIntosh class A produced by MF has a unique class.
Reading a bit I noticed the possibility of biasing the amp in class AB bias and move it closer to the class A. .. I noticed that in the two power amplifiers MA 6500 there are two trimmer (I think) move this polarization.
First of all try to put some pictures so you can confirm this hypothesis, but I wanted to know if you think this polarization by moving the sound of my McInsh if you can improve and how do I figure out what the maximum limit for this polarization.
Given that low volumes do not listen to, that my room is 6 x 4 and that my speakers are a pair of S10 Monito Audio (91dB sensitivity).
In practice, I ask you to be able to improve the sound of my McIntosh but can not be damaged.
Thank you.
I own a few years an amplifier McIntosh MA 6500. It 'a class AB amplifier in which I love for its powerful sound that it produces no listening fatigue. For some time I own a Musical Fidelity X-A1 that I use in a second plant: I must say though that sounds better than the McIntosh class A produced by MF has a unique class.
Reading a bit I noticed the possibility of biasing the amp in class AB bias and move it closer to the class A. .. I noticed that in the two power amplifiers MA 6500 there are two trimmer (I think) move this polarization.
First of all try to put some pictures so you can confirm this hypothesis, but I wanted to know if you think this polarization by moving the sound of my McInsh if you can improve and how do I figure out what the maximum limit for this polarization.
Given that low volumes do not listen to, that my room is 6 x 4 and that my speakers are a pair of S10 Monito Audio (91dB sensitivity).
In practice, I ask you to be able to improve the sound of my McIntosh but can not be damaged.
Thank you.
Hi advize you dont even begin to try it . Class A is very inefficient compared to AB .At least 50% of the power is taken in biasing the o/p devices and as a result the heat sinks are massively bigger .You could end up cooking the MA6500.
Thank you.
I understand that it can be dangerous if you overdo it. But do you think if there is even a chance for some kind of little change? 😕
When I use the amp for hours it is really very little heat...
I understand that it can be dangerous if you overdo it. But do you think if there is even a chance for some kind of little change? 😕
When I use the amp for hours it is really very little heat...
I've often wondered the same thing for my own other amps. I have 6 nearly-identical professional fan-cooled MOSFET amps (I hope soon to have 8 as soon as I can get the money together for 2 more). I have more power than I need, but I love the way they sound. I have often contemplated removing the individual fans and installing a commercial squirrel-cage air handler (meant for a furnace or air conditioner) to pressurize each entire rack case (4 amps in each) without making too much noise (amps in another room anyway). Then I could alter the bias for more class-A operation and still get rid of the heat. But I don't know whether it's worth it without doing it and having a listening comparison.
There is not only bias which is important. Whole topology of the amplifier is chosen such way that it works as it should. Everything is balanced. So only to crank up bias isn't enough. And it is risky. Power supply, o/p devices, heatsinks ...everything must be calculated and dimensioned properly...
Cheers
Cheers
Dado
provided the bias has been optimally adjusted and you would expect it had been at the factory then there is nothing to be gained and everything to be lost
provided the bias has been optimally adjusted and you would expect it had been at the factory then there is nothing to be gained and everything to be lost
Cyclecamper
i agree with Tajzmaj if you want class A operation you design for it, everything is put under so much more stress .
i agree with Tajzmaj if you want class A operation you design for it, everything is put under so much more stress .
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For each AB amp there is a point at which distortion will be minimized as it goes from underbiased with crossover distortion to overbiased with gm-doubling distortion (a little overbias usually is a lot less critical). It takes someone equipped to perform meaningful amplifier measurements (with a dummy load and all) to adjust bias accordingly.
It seems this model is about 10 years old at most. I would expect bias setting to be stable over such a relatively short timespan. If it was adjusted properly at the factory, this should still be the case now.
Class A operation is a lot more attractive in a headphone amplifier, where you can afford driving most anything to fairly high levels in A bias with just a handful of watts of power dissipation.
It seems this model is about 10 years old at most. I would expect bias setting to be stable over such a relatively short timespan. If it was adjusted properly at the factory, this should still be the case now.
Class A operation is a lot more attractive in a headphone amplifier, where you can afford driving most anything to fairly high levels in A bias with just a handful of watts of power dissipation.
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