Principally your formula is right, except that you can get that simpler, as sqrt2^2 = 2, you can use (70*70/2) / 8.
But, an amp can never put out the full voltage, and the psu drops voltage when driven hard. So it's more likely that you have max 60v, giving 60*60/16 = 225w.
But, you will not notice the difference, as to perceive double the loudness you need 10 times the power. Damn logarithmic perception of human sensors... A 500watt amplifier plays only double as loud as a 50watt amp...
Mike
But, an amp can never put out the full voltage, and the psu drops voltage when driven hard. So it's more likely that you have max 60v, giving 60*60/16 = 225w.
But, you will not notice the difference, as to perceive double the loudness you need 10 times the power. Damn logarithmic perception of human sensors... A 500watt amplifier plays only double as loud as a 50watt amp...
Mike
Hi Med,
you must take account of losses from the power supply (PSU) and through the amplifier.
I have an amplifier that runs on +-72Volts but peak voltage into an 8r load is just 55Volts.
This is just 190W into 8r.
It is much worse trying to drive a 4r load.
You should also consider the current capability of the PSU and ouput stage when trying to assess the maximum power that an amplifier can deliver.
you must take account of losses from the power supply (PSU) and through the amplifier.
I have an amplifier that runs on +-72Volts but peak voltage into an 8r load is just 55Volts.
This is just 190W into 8r.
It is much worse trying to drive a 4r load.
You should also consider the current capability of the PSU and ouput stage when trying to assess the maximum power that an amplifier can deliver.
So can you answer this:
http://www.diyaudio.com/forums/attachment.php?s=&postid=500215&stamp=1098885375
This amplifier needs 65 and 70 V
Why?
What would happend if I wolud connect it to +/- 70 V only?
And what is the maximum theoretical power with 8 ohm speaker?
http://www.diyaudio.com/forums/attachment.php?s=&postid=500215&stamp=1098885375
This amplifier needs 65 and 70 V
Why?
What would happend if I wolud connect it to +/- 70 V only?
And what is the maximum theoretical power with 8 ohm speaker?
Do not use that circuit.
Do not use that circuit, it won't work properly. This is the circuit that I came up with during the development of the amp and it did not perform well on the bench. You will find it and the final schematic in the thread "Power Amp Under Develoment".
Cheers
Q
medogrizli said:
Do not use that circuit, it won't work properly. This is the circuit that I came up with during the development of the amp and it did not perform well on the bench. You will find it and the final schematic in the thread "Power Amp Under Develoment".
Cheers
Q
The correct transformer selection;
This amplifier "Brother of Quasi" must not be connected to rails over +/- 70v DC at idle. This means that the transformer selected must not be more than 50v 0 50v with no load connected.
I.e; 50v - 0.6v (rectifier) * 1.414 = 69.9 volts.
Under full power this will drop by about 10% to 63 volts and the amp will drop a further 5 volts or so leaving about 58 volts.
58 volts * 0.707 = 41v RMS = 210 watts @ 8 ohms.
If the transformer selected is 50v 0 50v at its rated output then the idle DC rail voltage (77v) will exceed the capability of the amp and may cause you some grief.
I guess the 200 watt @ 8 ohms is now well and truly proven by enough of us.
Cheers
Q
This amplifier "Brother of Quasi" must not be connected to rails over +/- 70v DC at idle. This means that the transformer selected must not be more than 50v 0 50v with no load connected.
I.e; 50v - 0.6v (rectifier) * 1.414 = 69.9 volts.
Under full power this will drop by about 10% to 63 volts and the amp will drop a further 5 volts or so leaving about 58 volts.
58 volts * 0.707 = 41v RMS = 210 watts @ 8 ohms.
If the transformer selected is 50v 0 50v at its rated output then the idle DC rail voltage (77v) will exceed the capability of the amp and may cause you some grief.
I guess the 200 watt @ 8 ohms is now well and truly proven by enough of us.
Cheers
Q
Re: Re: Do not use that circuit.
If you send me an email, I'll send you all the info you need.
The amp works very well and has been auditioned and approved by some very fussy audiophiles. Remember though that the amps performance has a lot to do with the physical PCB layout.
If you want to discuss that amp further you should do so in the other thread. I want this one to revolve around "Brother of Quasi".
Cheers
Q
medogrizli said:
If you send me an email, I'll send you all the info you need.
The amp works very well and has been auditioned and approved by some very fussy audiophiles. Remember though that the amps performance has a lot to do with the physical PCB layout.
If you want to discuss that amp further you should do so in the other thread. I want this one to revolve around "Brother of Quasi".
Cheers
Q
Re: The correct transformer selection;
Sorry but I am interested in the amplifier not in power supply : ILL BUILD SMPS !! that ALVAYS DELIVER exactly +/- 70 V NO MATTER LOAD or current!!!
thats my projest forst to deelop or buld SMPA : there is thread "offline SMPS" on the power supply forum
SO there in the schematics there are two volatae needed +/-70V for first and second stage and +/- 60 V for OUTPUT mosfets :
Can I use +/- 70 V only !?
How can ou use only irfp450 : Only N -type : without usnig complemetary P-type mosfet?
Usually mosfet amplifiers has less power compared to biplar amplifiers in the output stage ?!
mail: velikigrizli@gmail.com
thanks
quasi said:
Sorry but I am interested in the amplifier not in power supply : ILL BUILD SMPS !! that ALVAYS DELIVER exactly +/- 70 V NO MATTER LOAD or current!!!
thats my projest forst to deelop or buld SMPA : there is thread "offline SMPS" on the power supply forum
SO there in the schematics there are two volatae needed +/-70V for first and second stage and +/- 60 V for OUTPUT mosfets :
Can I use +/- 70 V only !?
How can ou use only irfp450 : Only N -type : without usnig complemetary P-type mosfet?
Usually mosfet amplifiers has less power compared to biplar amplifiers in the output stage ?!
mail: velikigrizli@gmail.com
thanks
quasi said:
So if it exceeds +/- 70 V what will burn : first differential stage or ?
So mosfe version is not "concerned" if wxceeding +/-70V
Do bipolar version give more power than mosfet version
You build all the versions I presume: so what do you think what sounds better : mosfer or bipolar version?
medogrizli said:
If the output stage is used into 4 ohms then the output stage could be in danger. The other stages will be fine, but may be destroyed if the output stage goes short cct.
The bipolar will give slightly more power for the same rails, but the mosfet design can be pushed harder.
I have not yet built the bi-polar design. The mosfet design is a proven performer and will be hard to beat in terms of sonics and robustness.
Cheers
quasi said:
So whats is ABSOLUTE maximum rating for mosfet version concerned to power supply ?
you say output stage can be in danger : Conerned to head disipated (max current) or maximum voltage that Uds mosfets can handle?
Can this design be changed to even higher voltages like Holton AV800 type? or can it be bridged work in bridge version?
concrned the difference in power between mosfet and bipolar:
I read somwhere that +/70 V mosfet can have maximum of 200-250W at 8 ohm and Bipolar can have 350W with +/70V cause mosfet design needs aditional 6V for "biasing" (dont know how to say that in english)
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