One of my tweaks/mods of my AV Marantz SR4500 was to increase the bias -> better sound too. More bass and clean sound. Music with more energy. 3-D? I think the same... 2-D 🙁, but usually I listen to in near field, unless the music excites me, now more frequently than a week before!
Well, Hugh must to know something 😉
Well, Hugh must to know something 😉
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Higher bias: class AB amps work like class A few watts more, if I am not wrong. In my AV -> only more bass and cleanner sound. And more heat but until reasonable, even in the Mediterranean summer.
You are right, I should have asked better: how much the NAKSA 80 works as class A and how much with the new bias?
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Maty,
I have not experimented with the NAKSA, or the new SAKSA, under heavy bias. I have tried it at 150mA, and aside from producing quite a bit of heat, it does sound richer and more scale.
When you do this you increase the range of both outputs on. At 150mA quiescent, I make this range 6Vpp on LTSpice, which corresponds to 36/64=547mW, not a lot of power in Class A, but probably worthwhile for very quiet listening. Certainly the transitions are very smooth and well controlled.
Hugh
I have not experimented with the NAKSA, or the new SAKSA, under heavy bias. I have tried it at 150mA, and aside from producing quite a bit of heat, it does sound richer and more scale.
When you do this you increase the range of both outputs on. At 150mA quiescent, I make this range 6Vpp on LTSpice, which corresponds to 36/64=547mW, not a lot of power in Class A, but probably worthwhile for very quiet listening. Certainly the transitions are very smooth and well controlled.
Hugh
Only one more question.
From NAKSA 80, brochure: "300VA toroid with two 30 Vac secondary windings"
How much higher could the voltage be? With (or not) the N80 heatsinks.
From NAKSA 80, brochure: "300VA toroid with two 30 Vac secondary windings"
How much higher could the voltage be? With (or not) the N80 heatsinks.
Maty,
I don't like to go over 45V on these 280W mosfets. Reason: the heatsink needs more capacity at 50V, and I have some belief that stability and longevity is superior under 50V rails.
But they are very low Rdson, around 100 milliohms, so they really do drive rock and orchestral music very well.
Hugh
I don't like to go over 45V on these 280W mosfets. Reason: the heatsink needs more capacity at 50V, and I have some belief that stability and longevity is superior under 50V rails.
But they are very low Rdson, around 100 milliohms, so they really do drive rock and orchestral music very well.
Hugh
Just looked at this thread again as I just had the lids off my Soraya's to replace a fuse (it was only 3amp, must of run out of 7.5amp ones the last time I changed it), anyway, decided to check the bias which I originally set at 65mv, both channels were at 60mv, just wondering again what I should try as the heatsinks never even get warmish running Vaf I93's at high levels
Just checked - I use 7a fuses on my Soraya monoblocs. 🙂
Yes, as you increase bias current - the heatsinks get warmer.
But if yours "never even get warmish " ... I would thoroughly suggest increasing the bias reading to 120mV.
Andy
Yes, Dennis, Andy is correct, and his advice excellent. Increase the bias to increase the Class A output, up to 120mV.
You could increase the fuses to 10A each.
Cheers,
Hugh
You could increase the fuses to 10A each.
Cheers,
Hugh
Thanks for the advice Andy and Hugh, I will head to the Aztronics to get new fuses, so does the increase in bias also increase current through the fuses?
I was also using some Holton based monos for bass, but I decided to tidy up my system and reduced wiring/clutter and have happily settled on the Aksas for full duties, I am tempted to maybe update the Holtons, they both have 400VA 45v toroids(which I would like to recycle), Hugh what would you suggest I purchase Aksa based these days that would suite?
I was also using some Holton based monos for bass, but I decided to tidy up my system and reduced wiring/clutter and have happily settled on the Aksas for full duties, I am tempted to maybe update the Holtons, they both have 400VA 45v toroids(which I would like to recycle), Hugh what would you suggest I purchase Aksa based these days that would suite?
Hi Dennis,
I just put in a lovely post and the system swallowed it, drat..........
That voltage will give you around 200W from 65V rails. My only offering for that is the Maya, made for it, and five generations on from the original AKSA and better of everything; resolution, musicality, depth of image, natural presentation, silence, etc.
A pair of warrantied 2 year modules of the Maya would cost $2600 plus GST, but I doubt you'd ever need any more amps in your life after that!! In a proper enclose and fully plug 'n play, the cost is $5600, much more expensive, but I would assume you have a nice enclosure you are quids ahead...... expensive, but the best.
Ciao,
Hugh
I just put in a lovely post and the system swallowed it, drat..........
That voltage will give you around 200W from 65V rails. My only offering for that is the Maya, made for it, and five generations on from the original AKSA and better of everything; resolution, musicality, depth of image, natural presentation, silence, etc.
A pair of warrantied 2 year modules of the Maya would cost $2600 plus GST, but I doubt you'd ever need any more amps in your life after that!! In a proper enclose and fully plug 'n play, the cost is $5600, much more expensive, but I would assume you have a nice enclosure you are quids ahead...... expensive, but the best.
Ciao,
Hugh
Aah - so that doesn't just happen to me! 🙂
Are these monobloc modules, Hugh? (So each needs its own traffo ... as Dennis has 2 traffos.)
Andy
Thanks for the info yes I have 2 very good thick aluminium gold anodised
"mono" enclosures with inbuilt heatsinks, is it possible to mono the Maya boards/power supplies? I did this with the power supply on my original 100n's
"mono" enclosures with inbuilt heatsinks, is it possible to mono the Maya boards/power supplies? I did this with the power supply on my original 100n's
Just found a picture of the Maya, looks like to separate boards so easy to make monoblocks by the looks of it.
Yes, Dennis, it's set up identically with one 300VA for each channel, and separate heatsinks for each channel. You can build it very easily as a monobloc.
I can give your more information through aspen01@optusnet.com.au, easier to send graphics and photos.
Hugh
I can give your more information through aspen01@optusnet.com.au, easier to send graphics and photos.
Hugh
Been experimenting with bias, does'nt seem to make a lot of difference between 70 and 120mv with my speakers, lids back on sitting at 115mv, still little/no heat. Hugh will 400va transformers by ok with the Maya?
Absolutely, Dennis. Normally I use good quality 300VA, and never had any complaints! 400VA would give you more capacity with 4R loads.......
I think you have bipolar outputs, Dennis, and they need only about 60mA quiescent, and more is very little difference in sound. This is not true of mosfet outputs, however.
Cheers,
Hugh
I think you have bipolar outputs, Dennis, and they need only about 60mA quiescent, and more is very little difference in sound. This is not true of mosfet outputs, however.
Cheers,
Hugh
