i am searching plans to build a power amplifier. so far, i think the best suited for me is the leach amp. but i found this schematics on On Semiconductor website. they are a 100W and a 200W amplifiers. they are very similar to the leach amp. i wonder if anyone built it, and how would it work at full power. do you guys think its a good design?
thank you very much,
On Semi site
Pilkar
😎
thank you very much,
On Semi site
Pilkar
😎
These amps are old classics from a design standpoint.
I wouldn't recommend the 200 watt unit for a beginner.
Another alternative is to scale up the A75 and run in AB,
also not for beginners.
I seem to recall that the Leach is simpler.
I wouldn't recommend the 200 watt unit for a beginner.
Another alternative is to scale up the A75 and run in AB,
also not for beginners.
I seem to recall that the Leach is simpler.
Pilkar,
I might be biased (no pun intended) but I would highly recommend the A75 as the best of the three amplifiers mentioned.
Now if only Mr.Pass would work his magic and produce a class AB Aleph-X. But then again he might already have the design hidden away........................ 😉
Jam
I might be biased (no pun intended) but I would highly recommend the A75 as the best of the three amplifiers mentioned.
Now if only Mr.Pass would work his magic and produce a class AB Aleph-X. But then again he might already have the design hidden away........................ 😉
Jam
I 2nd jam's recommendation.
A75 is a really good amp, if not a bit too complicated comparing to Alephs.😉
A75 is a really good amp, if not a bit too complicated comparing to Alephs.😉
Pilkar,
On Semi 100 and 200 W amplifiers are not a good choice if you want the best audio quality. Probably because their needless complexity.
Regards, Pierre Lacombe.
On Semi 100 and 200 W amplifiers are not a good choice if you want the best audio quality. Probably because their needless complexity.
Regards, Pierre Lacombe.
Pilkar,
I have just gone through this myself. There are lots of good sites out there to help you decide what to do.
Here is a listing of the sites I found most useful.
AKSA - www.aksaonline.com
Borbely Audio - www.borbelyaudio.com
Bottlehead - www.bottlehead.com
Elliott Sound Products - sound.westhost.com
Leach Amp - users.ece.gatech.edu/~mleach/lowtim/
Pass Labs - www.passdiy.com
Seal Electronics - www.sealelectronics.com/kits/index.htm
The Amplifier Institute - www.dself.demon.co.uk/ampins.htm
The Class-A Amplifier Site - www.gmweb.btinternet.co.uk/index.htm
Cut and paste the URLs that didn't automatically convert.
Also, I found the books by Randy Slone and Douglas Self to be good reads.
I decided on the AKSA, 😀 but its very much a personal preference on which one is right for you.
I have just gone through this myself. There are lots of good sites out there to help you decide what to do.
Here is a listing of the sites I found most useful.
AKSA - www.aksaonline.com
Borbely Audio - www.borbelyaudio.com
Bottlehead - www.bottlehead.com
Elliott Sound Products - sound.westhost.com
Leach Amp - users.ece.gatech.edu/~mleach/lowtim/
Pass Labs - www.passdiy.com
Seal Electronics - www.sealelectronics.com/kits/index.htm
The Amplifier Institute - www.dself.demon.co.uk/ampins.htm
The Class-A Amplifier Site - www.gmweb.btinternet.co.uk/index.htm
Cut and paste the URLs that didn't automatically convert.
Also, I found the books by Randy Slone and Douglas Self to be good reads.
I decided on the AKSA, 😀 but its very much a personal preference on which one is right for you.
The Leach amp is a much better choice, very good in fact. Or you could make an ESP project 3A amp though. It's a very simple, yet good design. 😀 Not the greatest bandwidth though.
My recommendation.
I have had a listen to a AKSA - www.aksaonline.com amplifier. The fifty-something watt one. It was just soooo easy to listen to. Relatively simple to construct too. I would get one myself if I wasn't cooking up something of my own.
GP.
I have had a listen to a AKSA - www.aksaonline.com amplifier. The fifty-something watt one. It was just soooo easy to listen to. Relatively simple to construct too. I would get one myself if I wasn't cooking up something of my own.
GP.
thanks!
well, thank you very much!! by the way, this is not my first proyect at all, so i do not rate myself as a beginner, but thank you very much for your replies. i am building a pair of PA speakers designed by myself (someday, when they are finished i will post pictures) rated at 450W RMS, and i am looking at the possibility to run a bi amped system. so, this amp would go for the top end of the spectrum (1K6 - 20K). i am aware of the fame of all of Nelson's Pass designs, so i`m interested in the "upgraded to AB" A75 amplifier. i will dig on the subject a bit more, but if anyone has already done it, help is welcome! i am considering the Leach amp too, since it has the PCB and all online, but here is when i really need the help of the experts. "AB" A75 or Leach? i need somewere near 150W RMS at 8 ohm. the Leach marginally reachs this, will the A75 deliver?
sorry for the long post, and thank you very much again!
Pilkar
😎
well, thank you very much!! by the way, this is not my first proyect at all, so i do not rate myself as a beginner, but thank you very much for your replies. i am building a pair of PA speakers designed by myself (someday, when they are finished i will post pictures) rated at 450W RMS, and i am looking at the possibility to run a bi amped system. so, this amp would go for the top end of the spectrum (1K6 - 20K). i am aware of the fame of all of Nelson's Pass designs, so i`m interested in the "upgraded to AB" A75 amplifier. i will dig on the subject a bit more, but if anyone has already done it, help is welcome! i am considering the Leach amp too, since it has the PCB and all online, but here is when i really need the help of the experts. "AB" A75 or Leach? i need somewere near 150W RMS at 8 ohm. the Leach marginally reachs this, will the A75 deliver?
sorry for the long post, and thank you very much again!
Pilkar
😎
For PA I would encourage you to build the Leach. You need the RFI flitering and the short circuit protection.
The small Leach with a 45-0-45 1KVA transformer and three pair of outputs does 160W/8R, 300W/4R with both channels driven 20hz~20Khz. I have been driving one into 2R since 1988.
Compared head -to-head with the QSC MX2000, a 1KW per channel rated PA amplifier, the QSC played only slightly louder in the midrange. The Leach sounded much cleaner in both the midrange and the highs. What surprised everybody was the Leach not only played louder in the bass, but it also sounded much tighter with more punch and seemed to go an octave deeper. The speakers were 2R with dual 4R 15" woofers (Klipsch K43) and a 2" HF driver (JBL2445+2380).
The big Leach with its series connected outputs will do 400W/8R, 600W/4R from a 65-0-65 1.8KVA transformer. If you want to drive 2R you will need to add another set of outputs. I built some with six pair of outputs per channel with a 24dB/oct crossover and 6th order EQ for the woofer plus a speaker relay. The boards were 4.5" X 14" with the heatsinks on the board. A pair of the boards formed a tunnel with the fan on the side (crossflow). I'm thinking of re-doing the board for back-to-front airflow using Hafler DH500 heatsinks, of which I have 50+ pcs.
The small Leach with a 45-0-45 1KVA transformer and three pair of outputs does 160W/8R, 300W/4R with both channels driven 20hz~20Khz. I have been driving one into 2R since 1988.
Compared head -to-head with the QSC MX2000, a 1KW per channel rated PA amplifier, the QSC played only slightly louder in the midrange. The Leach sounded much cleaner in both the midrange and the highs. What surprised everybody was the Leach not only played louder in the bass, but it also sounded much tighter with more punch and seemed to go an octave deeper. The speakers were 2R with dual 4R 15" woofers (Klipsch K43) and a 2" HF driver (JBL2445+2380).
The big Leach with its series connected outputs will do 400W/8R, 600W/4R from a 65-0-65 1.8KVA transformer. If you want to drive 2R you will need to add another set of outputs. I built some with six pair of outputs per channel with a 24dB/oct crossover and 6th order EQ for the woofer plus a speaker relay. The boards were 4.5" X 14" with the heatsinks on the board. A pair of the boards formed a tunnel with the fan on the side (crossflow). I'm thinking of re-doing the board for back-to-front airflow using Hafler DH500 heatsinks, of which I have 50+ pcs.
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