@jazzzman - Personally, I'm not very afraid of nonlinear capacitance, would not fret most MOSFETs at 12V. For 4 Ohm load you want >3A. 36 Watts dissipation(!), 18W out on paper, over 10W out at low THD. And the 11V peak needed is just within range of op-amp type preamps on +/-15V supply.
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With good sinks, you can push the bias on a MoFo higher than you might think. I've been running one for over a year now with bias set above 50w dissipation per channel/device. I'm using individual sinks for each mosfet and the mosfet is mated directly to the sink using only grease - no silpad or anything else. This makes the sink live, so some care must be exercised with where you place it.
With ceramic spacers and thermal heatsink compound connecting a large 600W IXYS MOSFET to a CPU cooler with heat pipes, I have been able to push 150w and the MOSFET body temp is only 65C. The heatsink is isolated in this case and thus not live. I have found that it is useful to connect the heatsink to chassis GND to reduce noise pickup and sometimes it even prevents oscilations from the capacitance created between the MOSFET and the heatsink.
One more Mofo question!
I have got some big-amps battery chargers from old telecom whatnots. Transformer 27 V and 6 kilo. The added electronics make 28 V DC of this. Of course I could research the old-fashioned electronics and reduce the voltage. But what about using a higher voltage and reconfiguring the output choke as a step down transformer?
Of course the preamp would need more output.
I have got some big-amps battery chargers from old telecom whatnots. Transformer 27 V and 6 kilo. The added electronics make 28 V DC of this. Of course I could research the old-fashioned electronics and reduce the voltage. But what about using a higher voltage and reconfiguring the output choke as a step down transformer?
Of course the preamp would need more output.
few more volts is not a problem , if you have heatsinking ..... or you can shave few volts wherever you fancy - either in regs itself or with ripple eater (cap multi)
why step down choke/autoformer?
why step down choke/autoformer?
that is 27.5 vac peak around 20 vac rms...
i bet the OPA454 high voltage op amp can swing this....
I got dinged the last time I mentioned my open source preamp here. I happen to sell PCBs for it but not stopping anyone from making their own with P2P or home etch or layout with Gerbers.
sharing schematics and selling boards are two different things, you can not have them both in a single thread, each has its own place in our board...
as long as you follow this, there should not be a problem..
in fact if you share schematics and will not share details, then that gets moved over to the vendor's threads....it has always been like that....
see, I told ya about coffee and ...... there's how I got to recollect Zeus
making output traffos for the Zeus will even be easier as you do not have an air-gap to mind about...inductance is higher too...
Well there are two threads. The technical discussion one is here:
AKSA's Lender Preamp with 40Vpp Output
The other one is in the GB forum.
many members know about this, so that they report posts they see as not in keeping...
been looking at that amp and there is local interest...we may come up with our layouts using thru hole parts... and our own gerbers...
been looking at that amp and there is local interest...we may come up with our layouts using thru hole parts... and our own gerbers...
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The Aksa Lender is already through hole. There is option for SMT daughterboard core amp modules but that is not a popular choice.
There is even a through hole daughterboard that will fit directly on the bolts of the M2X input stage and provide gain as well as buffering to drive the 600ohm Edcor signal transformer.
There is even a through hole daughterboard that will fit directly on the bolts of the M2X input stage and provide gain as well as buffering to drive the 600ohm Edcor signal transformer.
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I've finally gathered all the parts - save for two, which I could use a bit of advice on.
I'm using a 20V supply. I'm going to drive it with a BoFo, followed by an Edcor XSM10k/150 (1:8.2 turns). I want a higher voltage gain than the PC600/15k offers. Using this as a transformer vs. autoformer, TBD.
I'm looking at the M2x schematic as a reference on the Edcor.
My question is regarding the series RC network following the Edcor.
The M2x thread suggests this is tuned to the particular transformer (I couldn't find any application notes from Edcor). The M25 thread says you can skip it if you're not using the PC600/15k. Susan Parker doesn't appear to use any compensation in her Zeus power amp.
I don't own a scope at the moment, so I can only test with a DMM and my ears. Any guidance will be appreciated.
I'm using a 20V supply. I'm going to drive it with a BoFo, followed by an Edcor XSM10k/150 (1:8.2 turns). I want a higher voltage gain than the PC600/15k offers. Using this as a transformer vs. autoformer, TBD.
I'm looking at the M2x schematic as a reference on the Edcor.
My question is regarding the series RC network following the Edcor.
The M2x thread suggests this is tuned to the particular transformer (I couldn't find any application notes from Edcor). The M25 thread says you can skip it if you're not using the PC600/15k. Susan Parker doesn't appear to use any compensation in her Zeus power amp.
I don't own a scope at the moment, so I can only test with a DMM and my ears. Any guidance will be appreciated.
go without compensation of you don't have proper equipment
or , to play safe - you can put (well , why not) same RC across secondary side
if you're lacking top end , double R
or , to play safe - you can put (well , why not) same RC across secondary side
if you're lacking top end , double R
Great, thanks.
So what's the network for, then? Is this to align voltage and current phase? A little reading says increasing R in a series RLC will increase bandwidth, which would fit with your comment about top end.
It's not a question of 'if' I'm going to buy a scope, but 'when' 🙂
So what's the network for, then? Is this to align voltage and current phase? A little reading says increasing R in a series RLC will increase bandwidth, which would fit with your comment about top end.
It's not a question of 'if' I'm going to buy a scope, but 'when' 🙂
xformers (all ) are having lesser or greater resonance , resulting in peak in signal transfer
that's the way to tame it
that's the way to tame it
Makes sense. So I could probably find usable results with a DMM and something like this: Online Tone Generator?
Measure across the RC network - from the Edcor output to ground?
Measure across the RC network - from the Edcor output to ground?
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