"So, from a mathematical way I got real!"
Sorry, you flunked math class!
CE drops are close to 2V in a linear mode, the Leach has tripple output stage so 2 + 2 + 2 = 6V not to mention 7A peak current through two 0.33 ohm emitter resistors is another 1V and we still haven't figured out the power supply droop. Or how close the front end can get to the rail.
In reality the Leach can get within about 8V of the rail running with a real load with a real audio signal.
Hafler
DH120 ±52V 60W/8R (31V-P) 21V 'missing'
DH200 ±63V 100W/8R (40V-P) 23V 'missing'
DH500 ±93V 250W/8R (63V-P) 30V 'missing'
Adcom
GFA535 ±52V 60W/8R (31V-P) 21V 'missing'
GFA555 ±77V 200W/8R (56V-P) 21V 'missing'
My Leach with two 20,000µF and a 1KVA transformer
LSR&D101 ±63V 160W/8R (50V-P) 13V 'missing'
Sorry, you flunked math class!
CE drops are close to 2V in a linear mode, the Leach has tripple output stage so 2 + 2 + 2 = 6V not to mention 7A peak current through two 0.33 ohm emitter resistors is another 1V and we still haven't figured out the power supply droop. Or how close the front end can get to the rail.
In reality the Leach can get within about 8V of the rail running with a real load with a real audio signal.
Hafler
DH120 ±52V 60W/8R (31V-P) 21V 'missing'
DH200 ±63V 100W/8R (40V-P) 23V 'missing'
DH500 ±93V 250W/8R (63V-P) 30V 'missing'
Adcom
GFA535 ±52V 60W/8R (31V-P) 21V 'missing'
GFA555 ±77V 200W/8R (56V-P) 21V 'missing'
My Leach with two 20,000µF and a 1KVA transformer
LSR&D101 ±63V 160W/8R (50V-P) 13V 'missing'
"i have a question for you, i have this big transformer weighing in at about 30kg, uses a gauge 14 primary winding at 220 volts and a secondary winding of gauge 10 bifilliar wound at 120 volts center tapped, my intention is to build a leach superamp that can output 250watts at 8 ohms, 500watts at 4 ohms, and 1000watts at 2 ohms. also i have provided another winding to supply +/-80 volts to the first and second stages thru voltage regulators...what is you impression of this plan, how many pairs of output transistors do you think i will need, or is this plan feasible in the first place? "
That transformer looks like it would be good for 3KVA~4KVA, should be fine for audio at 1KW/2R in stereo.
Since the MJ11032/33 would be in series we could use the 40V SOA curves at your supply voltage. De-rating for say 55*C ambient temperature, good mounting (.3*C), good heatsinking(1.5*C), you could run about 40W per device and with the Rjc at 0.584*C the junction would be about 150*C, an OK value.
A 1KW amplifier will have about 400W of heat to get rid of so 400W/40W=10 devices, or 12 outputs per channel, 6 NPN and 6 PNP.
A high voltage tier for the front end and pre-driver stages would be nice, this would maximize power out and lower the dissipation in the output stage. You must use a Baker clamp to prevent the output stages from being driven into saturation. This is just a few diodes at the pre-driver stage.
That transformer looks like it would be good for 3KVA~4KVA, should be fine for audio at 1KW/2R in stereo.
Since the MJ11032/33 would be in series we could use the 40V SOA curves at your supply voltage. De-rating for say 55*C ambient temperature, good mounting (.3*C), good heatsinking(1.5*C), you could run about 40W per device and with the Rjc at 0.584*C the junction would be about 150*C, an OK value.
A 1KW amplifier will have about 400W of heat to get rid of so 400W/40W=10 devices, or 12 outputs per channel, 6 NPN and 6 PNP.
A high voltage tier for the front end and pre-driver stages would be nice, this would maximize power out and lower the dissipation in the output stage. You must use a Baker clamp to prevent the output stages from being driven into saturation. This is just a few diodes at the pre-driver stage.
Forget about the high voltage tier for the Super Leach, it would require too much modification.
On the regular Leach it is easy to do.
Unless you are using ±V of over 100V, or trying to use low voltage parts due to availability issues as these guys are having to do, skip the series connected outputs and just use the normal Leach with MJ21193/94 outputs and MJE15032/33 drivers.
On the regular Leach it is easy to do.
Unless you are using ±V of over 100V, or trying to use low voltage parts due to availability issues as these guys are having to do, skip the series connected outputs and just use the normal Leach with MJ21193/94 outputs and MJE15032/33 drivers.
That transformer looks like it would be good for 3KVA~4KVA, should be fine for audio at 1KW/2R in stereo.
Since the MJ11032/33 would be in series we could use the 40V SOA curves at your supply voltage. De-rating for say 55*C ambient temperature, good mounting (.3*C), good heatsinking(1.5*C), you could run about 40W per device and with the Rjc at 0.584*C the junction would be about 150*C, an OK value.
A 1KW amplifier will have about 400W of heat to get rid of so 400W/40W=10 devices, or 12 outputs per channel, 6 NPN and 6 PNP.
A high voltage tier for the front end and pre-driver stages would be nice, this would maximize power out and lower the dissipation in the output stage. You must use a Baker clamp to prevent the output stages from being driven into saturation. This is just a few diodes at the pre-driver stage.
djk,
i do not plan to use mj11032/33 power darlingtons, i want to use the mj15003/15004 outputs as they are available here...
as for the regulated front end, i plan to use a lower voltage say +/- 75 than the main rectified voltage of +/- 85, reason being the output rail voltages will sag under load and hopefully prevent output transistor saturation...so far i haven't come accross a design using this method...what do you think? btw using mj11032/33 output pairs what is your recommended number of pairs for the leach super amps out put stage? thanks for your patience, i appreciate it.....
Since the MJ11032/33 would be in series we could use the 40V SOA curves at your supply voltage. De-rating for say 55*C ambient temperature, good mounting (.3*C), good heatsinking(1.5*C), you could run about 40W per device and with the Rjc at 0.584*C the junction would be about 150*C, an OK value.
A 1KW amplifier will have about 400W of heat to get rid of so 400W/40W=10 devices, or 12 outputs per channel, 6 NPN and 6 PNP.
A high voltage tier for the front end and pre-driver stages would be nice, this would maximize power out and lower the dissipation in the output stage. You must use a Baker clamp to prevent the output stages from being driven into saturation. This is just a few diodes at the pre-driver stage.
djk,
i do not plan to use mj11032/33 power darlingtons, i want to use the mj15003/15004 outputs as they are available here...
as for the regulated front end, i plan to use a lower voltage say +/- 75 than the main rectified voltage of +/- 85, reason being the output rail voltages will sag under load and hopefully prevent output transistor saturation...so far i haven't come accross a design using this method...what do you think? btw using mj11032/33 output pairs what is your recommended number of pairs for the leach super amps out put stage? thanks for your patience, i appreciate it.....
If you're going to use MJ15003/04 for outputs and drive 2R you will still need 12 outputs per channel. If you are not sure how good your heatsink is you may want to go to 16 outputs per channel. The 1.5*C per device is only 0.125*C for one channel, or two 0.25*C sinks per channel.
The drive current required for these would make me move up to a pair of TO3P devices from the TO220 ones. Leach originally used the TO3 MJ15001/02 as drivers. I would choose something like the 2SA1302/2SC3281 pair.
If you are not going to run the front end off the same supply as the outputs you will need to re-do a bunch of stuff. I wouldn't do it. You would want to remove Q22, Q23, which would double power in Q12, Q13, and add a Baker clamp.
https://www.onsemi.com/pub/Collateral/AN1308-D.PDF
Something to study.
The drive current required for these would make me move up to a pair of TO3P devices from the TO220 ones. Leach originally used the TO3 MJ15001/02 as drivers. I would choose something like the 2SA1302/2SC3281 pair.
If you are not going to run the front end off the same supply as the outputs you will need to re-do a bunch of stuff. I wouldn't do it. You would want to remove Q22, Q23, which would double power in Q12, Q13, and add a Baker clamp.
https://www.onsemi.com/pub/Collateral/AN1308-D.PDF
Something to study.
djk,
i figured 16 transistors per output, just a hunch....fyi i will be using a filter bank consisting of 6 x 22k ufd/100 volts 'elna' electrolytic caps, one set for each channel, and an mda3506 also one for each channel, i figured since the supply will be putting out 1.4kw per channel at 2R and with the rails sagging at around 140 volts total, then we have an average of 10 amps per channel, so the rectifiers should be more than enough, what do you say?
anyways, i have those parts on hand already, what i need are the power transistors mj15003/04, i intend to use the same as drivers since i already fabbed 2 sets of boards with the heatsinks for to-3 type drivers incorporated with the boards the way leach originally arranged in his article.....
i still have my eyes on the front-end voltage regulators, i have incorporated a separate winding for it in that power transformer and i have already made the circuit board for it...the way i understand it,Q22, Q23,operate as cascode with Q12, Q13 and i believe i can still bias the bases of Q22, Q23 from the output stage, i just want to isolate the front-end from the output rails as much as possible...
thanks for the article, nice reading...i like to look at amp designs and maybe figure out what the designer intended to do, i studied electrical engineering and had been hooked at audio system since high school, a good 30 years ago....cheers!!!
i figured 16 transistors per output, just a hunch....fyi i will be using a filter bank consisting of 6 x 22k ufd/100 volts 'elna' electrolytic caps, one set for each channel, and an mda3506 also one for each channel, i figured since the supply will be putting out 1.4kw per channel at 2R and with the rails sagging at around 140 volts total, then we have an average of 10 amps per channel, so the rectifiers should be more than enough, what do you say?
anyways, i have those parts on hand already, what i need are the power transistors mj15003/04, i intend to use the same as drivers since i already fabbed 2 sets of boards with the heatsinks for to-3 type drivers incorporated with the boards the way leach originally arranged in his article.....
i still have my eyes on the front-end voltage regulators, i have incorporated a separate winding for it in that power transformer and i have already made the circuit board for it...the way i understand it,Q22, Q23,operate as cascode with Q12, Q13 and i believe i can still bias the bases of Q22, Q23 from the output stage, i just want to isolate the front-end from the output rails as much as possible...
thanks for the article, nice reading...i like to look at amp designs and maybe figure out what the designer intended to do, i studied electrical engineering and had been hooked at audio system since high school, a good 30 years ago....cheers!!!
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