djk
Further to this protracted question on PS electrolytic replacements...I did determine that you were correct on the diameter of the originals. 2.5" (63mm) x 4.125 (105mm) long. They are rated at 18000mfd at 75vdc.
I had the amp recapped, except for these, as I can't find a close match to fit the space. I am considering making a psb that I can mount an array of smaller value caps and connect into the psu. I would like to replace these as they are probably 20 years old.
Any suggestions would be great.
thanks,
Paul
Further to this protracted question on PS electrolytic replacements...I did determine that you were correct on the diameter of the originals. 2.5" (63mm) x 4.125 (105mm) long. They are rated at 18000mfd at 75vdc.
I had the amp recapped, except for these, as I can't find a close match to fit the space. I am considering making a psb that I can mount an array of smaller value caps and connect into the psu. I would like to replace these as they are probably 20 years old.
Any suggestions would be great.
thanks,
Paul
When you build it "faster" dear Jacco, sometimes the hell thing starts to oscilate
Because of triple darlington...and them you will have to block that bringing it back to be slow once again.
Here in Brazil, almost all professional amplifiers, made now a days, are Leach amplifier clone...people love them.
I do not like them.
regards,
Carlos
.............................................................................................
I have made that with a Volkswagen.... i have made it faster installing a 2 Litters kit, special camshaft, external oil radiators, special ignition system, 4 carburetors, special manifold and special exaust pipes.
The car was less tall and the front was lower than the rear..to allow some down pressure... tubes travelled over the roof to the front to capture air under pressure.
I have made it faster...but the hell thing was near to "take off" alike an airplane when reached 220 km per hour... i had to bring it back to a lower power... almost the same hell thing.
Carlos
Because of triple darlington...and them you will have to block that bringing it back to be slow once again.
Here in Brazil, almost all professional amplifiers, made now a days, are Leach amplifier clone...people love them.
I do not like them.
regards,
Carlos
.............................................................................................
I have made that with a Volkswagen.... i have made it faster installing a 2 Litters kit, special camshaft, external oil radiators, special ignition system, 4 carburetors, special manifold and special exaust pipes.
The car was less tall and the front was lower than the rear..to allow some down pressure... tubes travelled over the roof to the front to capture air under pressure.
I have made it faster...but the hell thing was near to "take off" alike an airplane when reached 220 km per hour... i had to bring it back to a lower power... almost the same hell thing.
Carlos
"do you need 75V?"
The LSR&D 101 runs at ±63V with nominal line voltage. He could probably use 80V snap-on caps. Apexjr has some 6800µF/80V for $4.50 each, three or four per rail would probably work. You could also build a board with dual fast rectifiers and use a total of eight caps to go quasi dual-mono.
http://www.apexjr.com/capacitorsR.html
"Because of triple darlington...and them you will have to block that bringing it back to be slow once again."
So just use a dual. Easy to do with the new higher Beta devices.
"I do not like them."
Just like the AKSA, the devil is in the details. Try building a stripped down version of the original Leach with the same output stage as the AKSA, with the same attention to detail as you would use on an AKSA.
The LSR&D 101 runs at ±63V with nominal line voltage. He could probably use 80V snap-on caps. Apexjr has some 6800µF/80V for $4.50 each, three or four per rail would probably work. You could also build a board with dual fast rectifiers and use a total of eight caps to go quasi dual-mono.
http://www.apexjr.com/capacitorsR.html
"Because of triple darlington...and them you will have to block that bringing it back to be slow once again."
So just use a dual. Easy to do with the new higher Beta devices.
"I do not like them."
Just like the AKSA, the devil is in the details. Try building a stripped down version of the original Leach with the same output stage as the AKSA, with the same attention to detail as you would use on an AKSA.
Hi djk,
Am I missing something here, what is wrong with triple darlington output, I think they are good. Why would one want to replace a well executed triple with a EF output stage. Both have their advantages and disadvantages.
I think what Carlos doesnt like here is the complementary inputs. I find the single input ltp amps have a more forward presentation specially in the midrange, some prefer this. Some of the most well regarded ss amps in the world are complementary though, matter of taste and preference, like food. Ive listened to both (complementary and non) and both can sound great depending on execution, that goes for the output stage too.
We should catch Carlos out, send him a good complementary design where he cannot distinguise the topology and get a review from him. We should include a no feedback and a current feedback type too.
Am I missing something here, what is wrong with triple darlington output, I think they are good. Why would one want to replace a well executed triple with a EF output stage. Both have their advantages and disadvantages.
I think what Carlos doesnt like here is the complementary inputs. I find the single input ltp amps have a more forward presentation specially in the midrange, some prefer this. Some of the most well regarded ss amps in the world are complementary though, matter of taste and preference, like food. Ive listened to both (complementary and non) and both can sound great depending on execution, that goes for the output stage too.
We should catch Carlos out, send him a good complementary design where he cannot distinguise the topology and get a review from him. We should include a no feedback and a current feedback type too.
"Am I missing something here, what is wrong with triple darlington output"
Nothing, as far as I am concerned. It just seemed he was complaining to complain, so I suggested he could simplify it if he wanted.
"I think what Carlos doesnt like here is the complementary inputs"
Could be.
For the longest time I thought an amplifier had to have the complementary input stage to sound good, all the amplifiers I liked were of that design.
Many years down the road I modded a simple diff pair with Vas amplifier (McIntosh), just added a bunch of cheap bypass caps in the right spot.
It sounded better than most complementary input stage amplifiers (that didn't have bypass caps in the right spot), sounding more like a Leach than a McIntosh.
At that time it became obvious that 'the devil is in the details'.
Unfortunately I don't have enough time to try every idea I can come up with, so sometimes I just stick with recommending what I know works (the basic Leach topology).
Nothing, as far as I am concerned. It just seemed he was complaining to complain, so I suggested he could simplify it if he wanted.
"I think what Carlos doesnt like here is the complementary inputs"
Could be.
For the longest time I thought an amplifier had to have the complementary input stage to sound good, all the amplifiers I liked were of that design.
Many years down the road I modded a simple diff pair with Vas amplifier (McIntosh), just added a bunch of cheap bypass caps in the right spot.
It sounded better than most complementary input stage amplifiers (that didn't have bypass caps in the right spot), sounding more like a Leach than a McIntosh.
At that time it became obvious that 'the devil is in the details'.
Unfortunately I don't have enough time to try every idea I can come up with, so sometimes I just stick with recommending what I know works (the basic Leach topology).
IMHO, the Leach super amp is one topology that lends itself to a myriad of posible transitors used, especially at the output....i have built one such unit using 2N3055/MJ2955 with rails lowered to around +/-55volts....
the resulting sound was liked by those who heard the sound of the amp...
Happy New year too Senor Carlos......
gless said:
you won't find any anywhere....
the thing to do is scale down some componenets like the input ltp resistors and zener diodes at the bases of the input cascode transistors, in the original leach, two 20volt zeners were used, for a +/-55volt rails, that goes down ot just one zener rated 27volts, 1 watt.
other components ramain as is....
Leach amp capacitors
I'm re-building an old non-working Leach amplifier and was wondering about acceptable capacitor voltage ratings.
The original reservoir caps(10,000uf/75v) are leaky . I measure about 62Vdc(no load) at their output. I will replace them with 80v ones, since this is a commonly available rating.
I've got a bunch of 50V caps; would these be useable at the input stage since the Zeners supposedly clamp the voltage at 40Vdc?
In the second stage, for the second stage the original 75v caps need replacing. What is the minimum voltage rating usable here(I imagine 50v caps are too low for this)?
I'm re-building an old non-working Leach amplifier and was wondering about acceptable capacitor voltage ratings.
The original reservoir caps(10,000uf/75v) are leaky . I measure about 62Vdc(no load) at their output. I will replace them with 80v ones, since this is a commonly available rating.
I've got a bunch of 50V caps; would these be useable at the input stage since the Zeners supposedly clamp the voltage at 40Vdc?
In the second stage, for the second stage the original 75v caps need replacing. What is the minimum voltage rating usable here(I imagine 50v caps are too low for this)?
you are of course correct, that is why with +/-55 rails, there is no more than 27 volts accross each CE of the 2n3055/Mj2955, got it?
this is becuase they are stacked in series, are you familiar with the super leach amp? do you understand?
i built it in 1990, and still alive today acoording to the owner....have you ever built a super leach amp?
this is becuase they are stacked in series, are you familiar with the super leach amp? do you understand?
i built it in 1990, and still alive today acoording to the owner....have you ever built a super leach amp?
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