Hi smokingmachine,
Normally, one would use standard audio outputs like the MJ21195 and MJ21196. The collector current rating is lower. You would also use audio driver transistors, like another one of these. Note that you should be using 4 to 6 of these outputs per type for this output power. A large heatsink will be required.
Can you post the schematic you intend to use? There may be other issues at these high supply voltages.
-Chris
Normally, one would use standard audio outputs like the MJ21195 and MJ21196. The collector current rating is lower. You would also use audio driver transistors, like another one of these. Note that you should be using 4 to 6 of these outputs per type for this output power. A large heatsink will be required.
Can you post the schematic you intend to use? There may be other issues at these high supply voltages.
-Chris
Hi Smoking,
there are hundreds of BJTs suitable for +-90V.
Look for Vce0>180V.
However, if you choose some close to this limit you will often find that the SOAR at 90V is not as good as one rated at 230Vce0.
Download the datasheets for a few and start extracting the permitted current at your chosen rail voltage to make comparisons.
MJE 21193/4 as well as the 21195/6 mentioned earlier are possible candidates.
there are hundreds of BJTs suitable for +-90V.
Look for Vce0>180V.
However, if you choose some close to this limit you will often find that the SOAR at 90V is not as good as one rated at 230Vce0.
Download the datasheets for a few and start extracting the permitted current at your chosen rail voltage to make comparisons.
MJE 21193/4 as well as the 21195/6 mentioned earlier are possible candidates.
Hi smokingmachine,
I don't know of any darlingtons suitable for audio use with those ratings. They would be slow.
Use the normal BJT's and use a driver transistor. You are making your own, much improved darlington. Look at the SOA ratings to determine how many outputs you need. I'll bet more than you're thinking right now. Include extra for non-resistive loads.
-Chris
I don't know of any darlingtons suitable for audio use with those ratings. They would be slow.
Use the normal BJT's and use a driver transistor. You are making your own, much improved darlington. Look at the SOA ratings to determine how many outputs you need. I'll bet more than you're thinking right now. Include extra for non-resistive loads.
-Chris
Hi,
someone posted the opinion that to produce an effective output stage that can deliver adequate current into a reactive load at a phase angle upto 45degrees you need the power rating of the devices per rail to equal 3 times the output power of the amplifier.
As an example 100W into 8z at 45degrees phase angle needs two 150W devices per rail.
On that basis, 800W @45degrees would need ten 250W devices per rail. i.e. 40 devices for a stereo amp.
With careful design you may manage with slightly fewer devices, but I would counter that by suggesting the design should safely deliver into a 60 degree phase angle reactive load and as a result would need even more device pairs.
someone posted the opinion that to produce an effective output stage that can deliver adequate current into a reactive load at a phase angle upto 45degrees you need the power rating of the devices per rail to equal 3 times the output power of the amplifier.
As an example 100W into 8z at 45degrees phase angle needs two 150W devices per rail.
On that basis, 800W @45degrees would need ten 250W devices per rail. i.e. 40 devices for a stereo amp.
With careful design you may manage with slightly fewer devices, but I would counter that by suggesting the design should safely deliver into a 60 degree phase angle reactive load and as a result would need even more device pairs.
Hi Andrew,
With current limiting you can squeek away with fewer parts too. There is the heat issue to deal with.
Ah, young men with dreams of high power amplifers.
As the voltage goes up, and the energy goes up the reality becomes far more complicated. That's why you can't take a low power design and scale it up.
-Chris
With current limiting you can squeek away with fewer parts too. There is the heat issue to deal with.
Ah, young men with dreams of high power amplifers.
As the voltage goes up, and the energy goes up the reality becomes far more complicated. That's why you can't take a low power design and scale it up.-Chris
Hi Andrew,
At 800 watts it's music??
Amazingly, when this level of real power is delivered, speakers tend to smoke. If it's not that, the user(s) will attempt to deliver this power through a 1/4" phone plug.
Look where this design started. MJ11015 and MJ11016. I have concerns about the Vas and other circuitry on top of these outputs. This project is probably a no-flyer from the start without a redesign.
-Chris
At 800 watts it's music??
Amazingly, when this level of real power is delivered, speakers tend to smoke. If it's not that, the user(s) will attempt to deliver this power through a 1/4" phone plug.
Look where this design started. MJ11015 and MJ11016. I have concerns about the Vas and other circuitry on top of these outputs. This project is probably a no-flyer from the start without a redesign.
-Chris
I have a question that fits into this thread somewhat. I have a choice in transformer size as I have not bought them yet. It's for a class AB amp. The choice here is between a 670VA toroid or a 820VA one. The difference is about $15. Also the outer dimentions are both 6.3", and the hight of the 670VA is 2.3", and 2.7" for the 820VA. 0.4" on hight and $15 does not seem that much difference to me. Oh yeh, and about 3 lbs weight. The goal of the circuit is to output 400Wrms. The smaller one should work but with slightly more voltage drop on the rails. Should I just go ahead and buy the 820VA instead of the 670? Or are these sizes completely wrong?
Thanx
Thanx
Actually I was thinking of 400W into 2 Ohms. More specifically I was thinking of this transformer. http://www.toroid.com/standard_transformers/rectifier_transformers/solid_state_amplifiers.htm
transformer # 767.382
This company also has kits that are cheaper where you can wind your own, I just wonder if it is worth the time and effort.
I don't even have a circuit yet, so it isn't too specific. It all starts with the PS though.
transformer # 767.382
This company also has kits that are cheaper where you can wind your own, I just wonder if it is worth the time and effort.
I don't even have a circuit yet, so it isn't too specific. It all starts with the PS though.- Status
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