Anyone know of a simple enough circuit that acts as a power amp for a power amp? i.e. A load buffer (current dumper?)
i.e. What i want is a power amp that has 1x to 2x voltage gain that it accepts 10v to 80v inputs form other power amplifer and drives the load (basically acts as a load buffer for the signal amp).
In other words lets say I have an integrated amp which sounds awesome at 8 ohm loads but like crap on 4 or 2 ohm loads... that I connect it to this supposed buffer amp that drives the load using the integrated amp as it's pre-amp....
It will basically be an output stage with 1 or 2x voltage gain (no need for input diff/ VA stages hopefully)...
Any ideas?
i.e. What i want is a power amp that has 1x to 2x voltage gain that it accepts 10v to 80v inputs form other power amplifer and drives the load (basically acts as a load buffer for the signal amp).
In other words lets say I have an integrated amp which sounds awesome at 8 ohm loads but like crap on 4 or 2 ohm loads... that I connect it to this supposed buffer amp that drives the load using the integrated amp as it's pre-amp....
It will basically be an output stage with 1 or 2x voltage gain (no need for input diff/ VA stages hopefully)...
Any ideas?
It would be a power amp for low impedances with good stability at low amplification. The idea is not so good imho.
1) What about an approved "normal" power amp and dropping the old one?
2) Add to your integrated amp some power transistors. But you will lose output protection and the amp will presumably deterioate.
Regards
1) What about an approved "normal" power amp and dropping the old one?
2) Add to your integrated amp some power transistors. But you will lose output protection and the amp will presumably deterioate.
Regards
Yes.... but this is for an AV room that needs a high WAF among other considerations... The main AV processor will drive this behemoth (which will be behind a wall) plus I can try different amps and see which do I prefer the sonics of. This buffer amp will let me do all that... not to mention drive any speaker out there without re-doing the rest of my system....
I do believe it will afford me the kind of freedom, that folks who never saw a pre-power combo could never dream of... Isn't it taking it to the next level?
By the way I misspoke about 1x gain.... it needs to be 2x gain.
Now Gimmie some ideas / circuits
Here's what I might end up with. 24 TO-3P (NJW1302/3281) per channel. Powered by Dual 1kVA Toroids with 50kuF per rail per channel CLC. But I need the precursor cuircuit.... The driver will also be a NJW1302/3281 or maybe just switchers driven by the integrated power amp (but then I lose My 2x gain) rails about +/- 95 vdc or so...
I do believe it will afford me the kind of freedom, that folks who never saw a pre-power combo could never dream of... Isn't it taking it to the next level?
By the way I misspoke about 1x gain.... it needs to be 2x gain.
Now Gimmie some ideas / circuits
Here's what I might end up with. 24 TO-3P (NJW1302/3281) per channel. Powered by Dual 1kVA Toroids with 50kuF per rail per channel CLC. But I need the precursor cuircuit.... The driver will also be a NJW1302/3281 or maybe just switchers driven by the integrated power amp (but then I lose My 2x gain) rails about +/- 95 vdc or so...
Thanks Dennis: This is a start....
What do the 2 caps do? Isn't the 5v rating too low (I am sure I am missing something obvious).
What resistor values you recommend for +/-90v?
This would need a bias circuit of sorts because the pre-amp will not pass any DC... what do you recommend?
Lastly what kind of gain would this stage have?
What do the 2 caps do? Isn't the 5v rating too low (I am sure I am missing something obvious).
What resistor values you recommend for +/-90v?
This would need a bias circuit of sorts because the pre-amp will not pass any DC... what do you recommend?
Lastly what kind of gain would this stage have?
Hi,
to get the quiescent voltage to fall from +-94.3Vdc to +-80.7Vdc I had to adjust the model to 13% regulation while delivering over 2kW into 1r0. At 1kW that would be around 6% regulation which is a pretty poor 1kVA transformer.
For 4ohm power delivery the regulation has to be set to 18% to fall from 94.9Vdc to 80.1Vdc while delivering 680W. I would consider a PSU that did that to be a disaster.
to get the quiescent voltage to fall from +-94.3Vdc to +-80.7Vdc I had to adjust the model to 13% regulation while delivering over 2kW into 1r0. At 1kW that would be around 6% regulation which is a pretty poor 1kVA transformer.
For 4ohm power delivery the regulation has to be set to 18% to fall from 94.9Vdc to 80.1Vdc while delivering 680W. I would consider a PSU that did that to be a disaster.
K-amps said:
Hi
Opinions are like as$ holes, everybody has one, so as for my opinion, I think you should build a HEC follower circuit using cheap HEXFET's. You would not have any GNF or anything, and it would have a high input impedance with good damping. If you overbuild the gate driving stage, you can add more FETs till your heart contends.
Just check out Bob's EC Mosfet amp OPS. Bootstrap the driving stages from the output for the extra drive voltage required. 
"What do the 2 caps do? "
Alow the transition from class A to AB at hiher power.
"Isn't the 5v rating too low (I am sure I am missing something obvious)."
No, the difference between the bases of the two sets of outputs is below 5V.
"What resistor values you recommend for +/-90v? "
Adjust value for about 100mA through the drivers.
"This would need a bias circuit of sorts because the pre-amp will not pass any DC... what do you recommend?"
No bias circuit required.
"Lastly what kind of gain would this stage have?"
Unity, it's just a buffer/follower. It's called a cool follower because of the caps. There is a hot follower (class A version) that has active current sources instead of the 390R, and no caps.
For unity gain one could also build the Stasis output stage, using ThermalTrack drivers. The Threshold S150/S300/S500 had 3/6/9 pair of outputs.
The basic Stasis output circuit could be modified for a voltage gain of 2X.
Alow the transition from class A to AB at hiher power.
"Isn't the 5v rating too low (I am sure I am missing something obvious)."
No, the difference between the bases of the two sets of outputs is below 5V.
"What resistor values you recommend for +/-90v? "
Adjust value for about 100mA through the drivers.
"This would need a bias circuit of sorts because the pre-amp will not pass any DC... what do you recommend?"
No bias circuit required.
"Lastly what kind of gain would this stage have?"
Unity, it's just a buffer/follower. It's called a cool follower because of the caps. There is a hot follower (class A version) that has active current sources instead of the 390R, and no caps.
For unity gain one could also build the Stasis output stage, using ThermalTrack drivers. The Threshold S150/S300/S500 had 3/6/9 pair of outputs.
The basic Stasis output circuit could be modified for a voltage gain of 2X.
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