The Marshall 3315 used a mj11015/mj11016.
Your mj11032/mj11033 are a little better in power and current
but likly a dropin based on the schematic.
http://www.drtube.com/schematics/marshall/3315-5150-pa.gif
Your mj11032/mj11033 are a little better in power and current
but likly a dropin based on the schematic.
http://www.drtube.com/schematics/marshall/3315-5150-pa.gif
djk said:
Now I have also got some MJ21193/94. You mentioned them to be very good for amp purposes in an other thread.
Do you have a schematic for an amp with them either using +/-45V or +/-90V?
I know you described such a circuit to me, but I´d like a circuit which already has been built and works safely...or did you built the described circuit?
I have couples of MJ11015/16 power darlington and I will be using it for my next project - the superleach amp. Do I need to change any values or just plug and play?
I'm currently building (60%done) my Rod's P3A with MJ15024/25 as OPT. Once done and working, I will change the OPTs to darlingtons - just for experiment.... bad idea???
I'm currently building (60%done) my Rod's P3A with MJ15024/25 as OPT. Once done and working, I will change the OPTs to darlingtons - just for experiment.... bad idea???
"Now I have also got some MJ21193/94. You mentioned them to be very good for amp purposes in an other thread.
Do you have a schematic for an amp with them either using +/-45V or +/-90V?
I know you described such a circuit to me, but I´d like a circuit which already has been built and works safely...or did you built the described circuit?"
The basic Leach design has been around for more than 25 years. You can run it as is from about ±40V~±70V.
The Super Leach has been around for more than 20 years. You can run it as is from about ±70V~±100V.
It is one of the best amplifiers I have ever heard. You do need to pay some attention to the quality of the parts, Leach discusses this in the construction notes.
The Crest 8000 is one of the most respected pro-sound amps made. If you look at the schematic it looks the same as the Super Leach, just more outputs and higher voltage.
Do you have a schematic for an amp with them either using +/-45V or +/-90V?
I know you described such a circuit to me, but I´d like a circuit which already has been built and works safely...or did you built the described circuit?"
The basic Leach design has been around for more than 25 years. You can run it as is from about ±40V~±70V.
The Super Leach has been around for more than 20 years. You can run it as is from about ±70V~±100V.
It is one of the best amplifiers I have ever heard. You do need to pay some attention to the quality of the parts, Leach discusses this in the construction notes.
The Crest 8000 is one of the most respected pro-sound amps made. If you look at the schematic it looks the same as the Super Leach, just more outputs and higher voltage.
djk said:
Thanks for these circuits.
I probably will give it a try.
But output power doesn´t seem very high - for the basic Leach design a power rating of 120W/8Ohm by using +/-56V...You should get approx. 180W/8Ohm from such a power supply.
I couldn´t find any hints on using lower power supplies, e.g. with +/-45V which mine is - hopefully this isn´t too low for this design
naldy,
if you want to use power darlingtons for the leach superamps, just omit the drivers for the output transistors and you should be fine...can you give me an idea of how much these power darlingtons cost? i can give minor modifications on the circuit if you want them.....in my case, i used the tip41c/tip42c transistors as replacement for the 2n34449/2n5412 transistors.....
if you want to use power darlingtons for the leach superamps, just omit the drivers for the output transistors and you should be fine...can you give me an idea of how much these power darlingtons cost? i can give minor modifications on the circuit if you want them.....in my case, i used the tip41c/tip42c transistors as replacement for the 2n34449/2n5412 transistors.....
"But output power doesn´t seem very high - for the basic Leach design a power rating of 120W/8Ohm by using +/-56V...You should get approx. 180W/8Ohm from such a power supply."
What makes you think that?
Real power supplies sag under load.
Real power lines sag under load.
Real amplifiers drop voltage across the outputs and the emitter resistors.
I see all these huge power output claims on the internet and it makes me ask: do these guys even own any test equipment?.
Get real.
"I couldn´t find any hints on using lower power supplies, e.g. with +/-45V which mine is - hopefully this isn´t too low for this design "
The original Leach ran on this voltage, download the article from the Leach web-site. Hint: the only thing that needs to be changed is the bias resistor for the zener diodes.
".....in my case, i used the tip41c/tip42c transistors as replacement for the 2n34449/2n5412 transistors....."
You used a 6A 100V transistor to sub for a part running at 200V at 50mA?
"I've checked the diagram of leach superamp and the output stage is a bit complicated. "
They are just series connected.
The original parts, MJ15003/04 had poor safe area above 50V so Leach put the outputs in series to share the voltage.
The MJ21193/94 have good safe area at 100V, no need to use the series connection.
Just use the regular Leach design and parallel more outputs, go to the higher voltage driver transistors, MJE15032/33, above ±75V.
While you could kludge the design to use the darlingtons, it is a total waste of time and money, they are expensive and have poor safe area.
What makes you think that?
Real power supplies sag under load.
Real power lines sag under load.
Real amplifiers drop voltage across the outputs and the emitter resistors.
I see all these huge power output claims on the internet and it makes me ask: do these guys even own any test equipment?.
Get real.
"I couldn´t find any hints on using lower power supplies, e.g. with +/-45V which mine is - hopefully this isn´t too low for this design "
The original Leach ran on this voltage, download the article from the Leach web-site. Hint: the only thing that needs to be changed is the bias resistor for the zener diodes.
".....in my case, i used the tip41c/tip42c transistors as replacement for the 2n34449/2n5412 transistors....."
You used a 6A 100V transistor to sub for a part running at 200V at 50mA?
"I've checked the diagram of leach superamp and the output stage is a bit complicated. "
They are just series connected.
The original parts, MJ15003/04 had poor safe area above 50V so Leach put the outputs in series to share the voltage.
The MJ21193/94 have good safe area at 100V, no need to use the series connection.
Just use the regular Leach design and parallel more outputs, go to the higher voltage driver transistors, MJE15032/33, above ±75V.
While you could kludge the design to use the darlingtons, it is a total waste of time and money, they are expensive and have poor safe area.
djk,
fyi i tested my leach super amp with mj11032/mj11033 at full load, ie 45 volts ac @1khz using my heatkit signal generator and 8 ohm dummy load, both channels driven for 5 minutes, i did not do the 1/3 power preconditioning....with my supply rails at +/-76 volts sagging at around 69 volts at full load...the amp survived the test with no parts over heating...i used a 4in fan blowing into the heatsinks....
fyi i tested my leach super amp with mj11032/mj11033 at full load, ie 45 volts ac @1khz using my heatkit signal generator and 8 ohm dummy load, both channels driven for 5 minutes, i did not do the 1/3 power preconditioning....with my supply rails at +/-76 volts sagging at around 69 volts at full load...the amp survived the test with no parts over heating...i used a 4in fan blowing into the heatsinks....
djk,
you may find our ways odd at times, if you can come to the philiipines and have a look at the amps that were built, i assure you you are going to have a coronary....but that's the way we are, we can not be stopped from building amps just because we don't have the correct parts, but i assure you the amps we build works, maybe not as relialble as it should be. you will be amazed at what we have done with the 2n3055's, it is the power transistor for poor peaple like us.....
you may find our ways odd at times, if you can come to the philiipines and have a look at the amps that were built, i assure you you are going to have a coronary....but that's the way we are, we can not be stopped from building amps just because we don't have the correct parts, but i assure you the amps we build works, maybe not as relialble as it should be. you will be amazed at what we have done with the 2n3055's, it is the power transistor for poor peaple like us.....
While you can make the darlingtons work, I just wouldn't use them.
http://users.ece.gatech.edu/~mleach/lowtim/fdbk.html
You cannot run the driver stage in class A like Leach does.
Plus, they are simply too much money for what you get.
My cost for two pair of MJE15030/31 drivers and four pair of MJ15015/16 outputs (enough for the full output stage for the Super Leach) is $12.92, four pair of MJ11032/33 are $32.12
The four pair of MJ15015/16 outputs have 1440W SOA at 60V, the four pair of MJ11032/33 have 960W of SOA at 60V.
Why spend more to get less?
I do understand your need to use what you have available to you, and it sounds like you have done a good job of that.
I have a J-FET front end running a Leach output stage with ten pairs of MJ15024/25 running on ±80V that drives 1.2KW at 1 ohm, I used another pair of MJ15024/25 as drivers and 2N3584/6421 as pre-drivers. It is a brute, and can run at full output without a fan.
http://users.ece.gatech.edu/~mleach/lowtim/fdbk.html
You cannot run the driver stage in class A like Leach does.
Plus, they are simply too much money for what you get.
My cost for two pair of MJE15030/31 drivers and four pair of MJ15015/16 outputs (enough for the full output stage for the Super Leach) is $12.92, four pair of MJ11032/33 are $32.12
The four pair of MJ15015/16 outputs have 1440W SOA at 60V, the four pair of MJ11032/33 have 960W of SOA at 60V.
Why spend more to get less?
I do understand your need to use what you have available to you, and it sounds like you have done a good job of that.
I have a J-FET front end running a Leach output stage with ten pairs of MJ15024/25 running on ±80V that drives 1.2KW at 1 ohm, I used another pair of MJ15024/25 as drivers and 2N3584/6421 as pre-drivers. It is a brute, and can run at full output without a fan.
djk said:
Well, you can easily compute this power rating...I also computed this power rating with assuming only 54V instead of 56V (for voltage drops). With 56V it would be nearly 200W/8Ohm.
To get 120W/8 Ohm "real" 44V on output line are enough - but Leach claims this power rating at running on 56V. 12V can´t be dropped...
So, from a mathematical way I got real!
dkj,
your point is well taken, i agree with you...if only we can get our hands on those transistors here in the philippines.....we have many japanese transistors available here....
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? thanks a lot.
your point is well taken, i agree with you...if only we can get our hands on those transistors here in the philippines.....we have many japanese transistors available here....
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? thanks a lot.
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