I didn't recommend separately regulating the front end VAS and output. I simply reported that some found that it offered sonic benefits. 😉 I think that is probably way overkill. There is a thread here somewhere about regulating everything.
Thanks for the GB Tad.
Thanks for the GB Tad.
Andrew,
Since I already have 4,700uf snap-ins for the PCB's, do you think I might be able to use a choke or a resistor in series between the main bank and the PCB-mounted caps to advantage here(my 75v rails are more than enough if there's a small voltage drop)?
Or should I place the 4,700's with the main bank, and use something smaller on-board (say, 2,200uf)? 😕
I don't want to be blowing fuses(I can do that with the stock 200C)...
TIA
OH, and thanks again Tad, for the G.B.(& all your hard work).
-Chas
searching components for best quality/price rate
While I waited for the arrival of the pcbs, I am searching the components, so I have prepared a datasheet that could be useful to others.
Ciao, Giuseppe.
While I waited for the arrival of the pcbs, I am searching the components, so I have prepared a datasheet that could be useful to others.
Ciao, Giuseppe.
tryonziess said:
2x 1kva? I can see why there would be little drop. Are you using Leach for MIG welding or audio applications? 😉
Agreed. I will pop the extra $$ and add inrush limiting...
Excellent! Thanks Tad
Doesn't Nelson use some 4kva tannies in some of his 200 watt amps. He is always saying that 5 times the output is a good figure -- of course that is class A -- and this is DIY Audio for fanatics. I was going to use 2 1.5kva but they are too big. Only a couple more dollars.
And I just happen to have an old 3 phase welder made in Italy I got out of the trash at work about 450 pounds. Now what can I do with that. I wonder maybe an X amp or something. I still have about 350 mosfets leftover from the A-75 project. I am firing it up Saturday. FINALLY. What a monster.
Jacco, I can not see the reference. Missing something? Little help.
When you turn off the amp power it still plays for about 2 minutes with the charge in the caps. Would that be free power. Just kidding.
It seems like a few of us including me chose to stretch Leach's design a bit with our increased rail voltages. He did design the
Super Leach for that did he not.
Tad
And I just happen to have an old 3 phase welder made in Italy I got out of the trash at work about 450 pounds. Now what can I do with that. I wonder maybe an X amp or something. I still have about 350 mosfets leftover from the A-75 project. I am firing it up Saturday. FINALLY. What a monster.
Jacco, I can not see the reference. Missing something? Little help.
When you turn off the amp power it still plays for about 2 minutes with the charge in the caps. Would that be free power. Just kidding.
It seems like a few of us including me chose to stretch Leach's design a bit with our increased rail voltages. He did design the
Super Leach for that did he not.
Tad
Jacco, I found it thanks.
One quote -- good sounding amplifiers do not use consistent power supply design. Quite interesting. Thanks Tad
One quote -- good sounding amplifiers do not use consistent power supply design. Quite interesting. Thanks Tad
Hi Clm,
+-58V supply through F4A fuses into +-10mF blew on every start up.
I changed to +-4700uF and they occasionally blew.
Reduced to +-4mF (4 off 1mF //) and the F4A survive.
Trial and error?
F4A fuses survived long term sinewave testing to 171W into 8r0 and survived short term sinewave testing to 312W into 4r0.
+-58V supply through F4A fuses into +-10mF blew on every start up.
I changed to +-4700uF and they occasionally blew.
Reduced to +-4mF (4 off 1mF //) and the F4A survive.
Trial and error?
F4A fuses survived long term sinewave testing to 171W into 8r0 and survived short term sinewave testing to 312W into 4r0.
Chas
Try CL30 for current limiting. It's 2R5 cold and 0R34 at 2 amps. One per rail - driving both channels should work well.
They can also be used on the mains line for global inrush protection.
You may still need a fairy hefty rail fuse - 6 A or so. That should still provide some protection against catastrophic failures. There is an old truism that output devices blow quickly to save the fuses. 🙄
TAD -
Class AB hardly stresses a transformer in home use. Class A is a different situation. The total current that a transformer delivers is roughly twice the output current. The "extra" is the capacitor charging current. So if your transformer is only rated at 3x the power consumed in the amplifier, you are running it at 67% of its rating steady state.
When the original Leach was designed, the MJ15002/3 were the highest voltage biggest SOA devices around. Even so, they weren't suitable for 80V rails of the super. The Low-TIM topology is sound and with enough properly rated output devices it is fine for higher rails.
Try CL30 for current limiting. It's 2R5 cold and 0R34 at 2 amps. One per rail - driving both channels should work well.
They can also be used on the mains line for global inrush protection.
You may still need a fairy hefty rail fuse - 6 A or so. That should still provide some protection against catastrophic failures. There is an old truism that output devices blow quickly to save the fuses. 🙄
TAD -
Class AB hardly stresses a transformer in home use. Class A is a different situation. The total current that a transformer delivers is roughly twice the output current. The "extra" is the capacitor charging current. So if your transformer is only rated at 3x the power consumed in the amplifier, you are running it at 67% of its rating steady state.
When the original Leach was designed, the MJ15002/3 were the highest voltage biggest SOA devices around. Even so, they weren't suitable for 80V rails of the super. The Low-TIM topology is sound and with enough properly rated output devices it is fine for higher rails.
I wonder why Dr. Leach has never visited any of the discussions on his protege.
And to think he did this design when he was very young. He might be able to offer up some good comments after 35 years of reading, studying and teaching the subject. I would welcome his input.
Nelson never seems to quit improving his toys. Of course he has to make a living at it.
Tad
And to think he did this design when he was very young. He might be able to offer up some good comments after 35 years of reading, studying and teaching the subject. I would welcome his input.
Nelson never seems to quit improving his toys. Of course he has to make a living at it.
Tad
It is kind of moot at this point. I will try and close the wiki group buy. All of the boards are spoken for until Friday. Then a few people have expressed prior interest in the no show boards.
Tad
Tad
Re: searching components for best quality/price rate
Distrelec Art. No. 821525 (6x13 mm LS 10 mm)
IMHO, bypass capacitors C22-C32 would be better polyproplylene, for example Evox Rifa PHE450AudioG said:
Distrelec Art. No. 821525 (6x13 mm LS 10 mm)
Where can you buy them at a reasonable price in the U.S. I had a hard time finding regular MKP Evox at the proper pcm.
There is not a real good source for Rifa and other high grade films in the States unless you pay audiophile rates at specialty outlets. When I ordered through RS components global the freight was murder. I tried to emulate Jens layout at Delta-Audio.
I agree with your choice I just could not find them. Someone want to run a group buy on film caps or Rifa electrolytics????
Come to a consensus on the parts and I could do this I suppose. Power supply electros in 100+ volts can get very expensive fast. I like the 47,000uf/100 volt Rifa caps as my first choice they retail at about 100.00 dollars EACH. It makes big trannies look cheap. Put 8 of those in your stereo Leach and your budget is -- what budget. We could save BIG here with a GB.
Be careful with the film caps watch the pcm closely. Speaking from past experience.
Tad
There is not a real good source for Rifa and other high grade films in the States unless you pay audiophile rates at specialty outlets. When I ordered through RS components global the freight was murder. I tried to emulate Jens layout at Delta-Audio.
I agree with your choice I just could not find them. Someone want to run a group buy on film caps or Rifa electrolytics????
Come to a consensus on the parts and I could do this I suppose. Power supply electros in 100+ volts can get very expensive fast. I like the 47,000uf/100 volt Rifa caps as my first choice they retail at about 100.00 dollars EACH. It makes big trannies look cheap. Put 8 of those in your stereo Leach and your budget is -- what budget. We could save BIG here with a GB.
Be careful with the film caps watch the pcm closely. Speaking from past experience.
Tad
PCM is the deminsion between the two legs of the film capacitor. On Jens BOM he tells you the width of the legs for each location usually 5mm, 10mm, etc.
Tad
Tad
Bob,
Is your website down? or no longer available? I'm trying to download the BOM of the 65V PSU for my Leach front end and as well as 15V.
Fred
Is your website down? or no longer available? I'm trying to download the BOM of the 65V PSU for my Leach front end and as well as 15V.
Fred
Case option
Hello,
first: Thank's to Tad for is application for we all,
I'm looking for a decent case with heatsink,
so I have discovered this: HiFi2000.it "pesante dissipante", height 4U, depth 300mm (12"), frontal panel 10mm and two heatshink as lateral panels, the depth 300mm has one continuos heatshink for side, while the deep of 400mm (16") has two 200mm heathsink for side.
It seems that the H=4U d=300mm is rated 0,35°C/W.
What do you think about?
Giuseppe
link to site hifi2000 pesante dissipante
Hello,
first: Thank's to Tad for is application for we all,
I'm looking for a decent case with heatsink,
so I have discovered this: HiFi2000.it "pesante dissipante", height 4U, depth 300mm (12"), frontal panel 10mm and two heatshink as lateral panels, the depth 300mm has one continuos heatshink for side, while the deep of 400mm (16") has two 200mm heathsink for side.
It seems that the H=4U d=300mm is rated 0,35°C/W.
What do you think about?
Giuseppe
link to site hifi2000 pesante dissipante