Hi,
what exactly happens, if the idle current is reduced to 1/10th of normal ?
My idea is to couple the volume pot with another one, that regulates the idle current.
Low volume - low current, high volume - full current.
Does the sound quality suffer, or is it possible to do that ?
Bernhard
what exactly happens, if the idle current is reduced to 1/10th of normal ?
My idea is to couple the volume pot with another one, that regulates the idle current.
Low volume - low current, high volume - full current.
Does the sound quality suffer, or is it possible to do that ?
Bernhard
It can be done, but the sound quality will change as the bias goes up and down. Depending on the design of the circuit, the amp may become unstable as the operating points change with the change in bias.
Grey
Grey
I think it's a good idea. I've seen some project in the gallery that had the adjustable bias option. And of course, you can always adjust bias to your taste.
I also think it is a nice idea. Sometimes the simples ideas are the nicest. I know that one of Andera Cioffulie's (?) amp has a Iq setting switch and my own amp has a Iq pot for adjustment .. why not couple such a pot or switch to your volume pot ..
I might bne that High Iq serve high linearity of the output stage but you could verify your self ..
It might very well be that the absence of cross-over distortion is far mopre important than large signal super linearity. .. I actually think that is the case... so we should design a variable Iq class A amp this weekend!
greetings,
thijs
I might bne that High Iq serve high linearity of the output stage but you could verify your self ..
It might very well be that the absence of cross-over distortion is far mopre important than large signal super linearity. .. I actually think that is the case... so we should design a variable Iq class A amp this weekend!
greetings,
thijs
😀
I was afraid, that I have to downgrade the A5, because power consumption would be too high for 4-way active speakers.
4 times the consumption of a normal stereo setup...
1200VA all the time...
But now...
If that works, maybe it is possible to do that with relais, as I use them for my volume control.
Maybe 1/8, 1/4, 1/2 and full is ok.
Is it true that the Aleph, because of its circuitry will always run classA even on smallest idle current ?
Two resistors will set the current per channel ?
Can I use the IRFP450 or 460 also ?
They are very easy to get for me.
My heatsinks, they have space for 64 TO3 mosfets...
That is 8 mosfets per channel.
I was afraid, that I have to downgrade the A5, because power consumption would be too high for 4-way active speakers.
4 times the consumption of a normal stereo setup...
1200VA all the time...
But now...
If that works, maybe it is possible to do that with relais, as I use them for my volume control.
Maybe 1/8, 1/4, 1/2 and full is ok.
Is it true that the Aleph, because of its circuitry will always run classA even on smallest idle current ?
Two resistors will set the current per channel ?
Can I use the IRFP450 or 460 also ?
They are very easy to get for me.
My heatsinks, they have space for 64 TO3 mosfets...
That is 8 mosfets per channel.
An externally hosted image should be here but it was not working when we last tested it.
Musical Central Heating ?
Bernard,
With volume control variable bias, you could have volume controlled central heating - best sound during cold winter ?. 😀
Regards, Eric.
Bernard,
With volume control variable bias, you could have volume controlled central heating - best sound during cold winter ?. 😀
Regards, Eric.
So, they pretty hungry on power, aren't they? At least you gonna keep them warm in winter.😉
Are they also impressive?
Are they also impressive?
The bass, which is not shown on the photos is very hungry. 🙁
Are my speakers impressive ? Everything still under construction. 🙄
On top is my plasma. 😛
The thing in the middle is a modified Infinity EMIM. 😎
On the bottom is a very usual 6" speaker. 🙂
Are my speakers impressive ? Everything still under construction. 🙄
On top is my plasma. 😛
The thing in the middle is a modified Infinity EMIM. 😎
On the bottom is a very usual 6" speaker. 🙂
In case that you reduce iddle current that much, you will obtain an increase of distortion. High iddle current reduces distortion for the class A amplifier.
Regarding speakers, I'd say they mach amplifier.
However, with quad-amped system I'd rather go for monoblocks to avoid long cables to the speakers. But of course it all depends what you have available. Check that link: http://passdiy.com/gallery/aleph5-p1.htm
It's Aleph 5 with adjustable bias. You can also e-mail owner and ask about differences with the different settings.
However, with quad-amped system I'd rather go for monoblocks to avoid long cables to the speakers. But of course it all depends what you have available. Check that link: http://passdiy.com/gallery/aleph5-p1.htm
It's Aleph 5 with adjustable bias. You can also e-mail owner and ask about differences with the different settings.
Nice pictures, now those 450/60 transistors
Here is the specifications for the 450 http://ec.irf.com/ec/adirect/ir?query=IRFP450&useWildCard=false&cmd=search
The minimum on-resistance is quite high. This in itself is not a big problem if you are using lots of them. However, this is a high voltage unit. To get desired switching characteristics, input capacitance suffers -- exacerbated by using many.
I would advise against using this unit, and I would expect the 460 to be a complete non-starter (second number usually indicates "generation" where newer is usually worse for audio). Besides, the cost of devices is low compared with total package (heatsinks, power, cabinet, connectors).
Petter
Here is the specifications for the 450 http://ec.irf.com/ec/adirect/ir?query=IRFP450&useWildCard=false&cmd=search
The minimum on-resistance is quite high. This in itself is not a big problem if you are using lots of them. However, this is a high voltage unit. To get desired switching characteristics, input capacitance suffers -- exacerbated by using many.
I would advise against using this unit, and I would expect the 460 to be a complete non-starter (second number usually indicates "generation" where newer is usually worse for audio). Besides, the cost of devices is low compared with total package (heatsinks, power, cabinet, connectors).
Petter
I think that I am over-heatsinking my aleph2. Would increasing the bias current make it sound better? How much higher can I increase it on the Aleph 2?
--
Brian
gte619j@prism.gatech.edu
--
Brian
gte619j@prism.gatech.edu
If you search the Forums, you should find a post that I did explaining the relationship between Aleph power and speaker impedance. This results in minimum required quiescent current and PSU voltage for a given power level at a certain impedance.
It is all pretty basic.
Petter
It is all pretty basic.
Petter
ok, so no 450/460.
Also my heatsinks are for TO3.
Any advice where to get suitable TO3 mosfets in Germany/Europe ?
If there is more distortion on low bias, no problem, as long as it is not getting too bad.
As background music it will be ok, and for seriously listening, I can pump up the idle ...
The Aleph5 with 6 different bias levels from the link ( isnt it a A3 ? ) is interesting...
This results in minimum required quiescent current and PSU voltage for a given power level at a certain impedance.
Yes, and so, for room level, I like to reduce the idle current.
Bernhard
Also my heatsinks are for TO3.
Any advice where to get suitable TO3 mosfets in Germany/Europe ?
If there is more distortion on low bias, no problem, as long as it is not getting too bad.
As background music it will be ok, and for seriously listening, I can pump up the idle ...
The Aleph5 with 6 different bias levels from the link ( isnt it a A3 ? ) is interesting...
This results in minimum required quiescent current and PSU voltage for a given power level at a certain impedance.
Yes, and so, for room level, I like to reduce the idle current.
Bernhard
Brian,
Nothing wrong with running your amp little cooler. When you'll build your amp you can play with different bias values and see how it affects sonics.
Nothing wrong with running your amp little cooler. When you'll build your amp you can play with different bias values and see how it affects sonics.
HPotter,
Thanks for your response. I was just worried that it would not run hot enough to sound good. I will play with it once I get it finished. I have my cases almost done for both channels.
--
Brian
gte619j@prism.gatech.edu
Thanks for your response. I was just worried that it would not run hot enough to sound good. I will play with it once I get it finished. I have my cases almost done for both channels.
--
Brian
gte619j@prism.gatech.edu
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