Hi All,
After many years away from hobby electronics I've decided to get my hands dirty again and build the Leach 4.5. My plan is to build it precisely as per Prof Leach's plans. Besides the enjoyment of doing this, I'd like to know that the end result will be better than my current setup, which is:
CD Player: Marantz CD7300
Amp: Marantz PM7200
Speakers: Bowers and Wilkins DM603 S3
I intend to reuse the CD player and speakers, possibly upgrading in the future sometime. In the opinion of the forum, can I expect as good or better performance with the Leach? Any opinions will be appreciated.
Toltec
After many years away from hobby electronics I've decided to get my hands dirty again and build the Leach 4.5. My plan is to build it precisely as per Prof Leach's plans. Besides the enjoyment of doing this, I'd like to know that the end result will be better than my current setup, which is:
CD Player: Marantz CD7300
Amp: Marantz PM7200
Speakers: Bowers and Wilkins DM603 S3
I intend to reuse the CD player and speakers, possibly upgrading in the future sometime. In the opinion of the forum, can I expect as good or better performance with the Leach? Any opinions will be appreciated.
Toltec
I don't know your amp nor your speakers.
Are the speakers 4ohm or 8ohm or some other impedance?
I would expect the Leach Lo Tim 4.5 to drive 8ohms very well, but with a two pair output stage and low efficiency, 4ohms speaker, it may not be at it's best. A big PSU will help.
The Leach is pretty good, I think you will be pleased.
Are the speakers 4ohm or 8ohm or some other impedance?
I would expect the Leach Lo Tim 4.5 to drive 8ohms very well, but with a two pair output stage and low efficiency, 4ohms speaker, it may not be at it's best. A big PSU will help.
The Leach is pretty good, I think you will be pleased.
Hi,
Leach amp is a very good choice. Why ? Because you will find all documentation on Leach's site, see FAQS for more details.
Regarding speaker impedance : No probleme for 4 ohms. This amp use two pairs of Bipolar (140 V 20 A 250 W !!) But it could be necessary to adjust current limiter. But is it realy necessary ? For normal use, i am not sure.
Please see those links :
Leach Amp Protection Circuit
The Leach Amp - Part 2
Regards,
Frédéric
Leach amp is a very good choice. Why ? Because you will find all documentation on Leach's site, see FAQS for more details.
Regarding speaker impedance : No probleme for 4 ohms. This amp use two pairs of Bipolar (140 V 20 A 250 W !!) But it could be necessary to adjust current limiter. But is it realy necessary ? For normal use, i am not sure.
Please see those links :
Leach Amp Protection Circuit
The Leach Amp - Part 2
Regards,
Frédéric
expect a lot more than 95W into 8r0 from the Leach.
I don't know where that figure came from.
I built the Leach clone with the 3pair output stage.
From 230:40+40Vac transformer I got 170W into 8r0, one channel driven. My 3pair of 230W plastic (MJL) devices has similar SOA to a 2pair To3 using 250W devices.
I got over 300W into 4r0, one channel driven, but that does not prove it is 4ohms capable.
Look at using the NJL devices with the integrated diodes. These 4 diodes would fit exactly into the Lo Tim 4.5
I don't know where that figure came from.
I built the Leach clone with the 3pair output stage.
From 230:40+40Vac transformer I got 170W into 8r0, one channel driven. My 3pair of 230W plastic (MJL) devices has similar SOA to a 2pair To3 using 250W devices.
I got over 300W into 4r0, one channel driven, but that does not prove it is 4ohms capable.
Look at using the NJL devices with the integrated diodes. These 4 diodes would fit exactly into the Lo Tim 4.5
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Thanks all for your input.
I'm in the process of buying components. I intend making the pcb myself. I'd prefer to use 2 oz copper but it seems that getting it in the UK is all but impossible unless you're willing to pay mad shipment prices from the US or the East. Is 1 oz ok?... perhaps doing as someone else suggested elsewhere and soldering copper wire along the high current traces. Any input would be appreciated!
Gary
I'm in the process of buying components. I intend making the pcb myself. I'd prefer to use 2 oz copper but it seems that getting it in the UK is all but impossible unless you're willing to pay mad shipment prices from the US or the East. Is 1 oz ok?... perhaps doing as someone else suggested elsewhere and soldering copper wire along the high current traces. Any input would be appreciated!
Gary
I would recommend 2oz copper and laminate thicker than 1.6mm (0.062") for power amps. A PCB house starts with 1oz and electroplates to 2oz, for typical double-sided boards. Solder has almost 10X resistance of copper, so adding solder to PCB traces does not help as much as we think.
diy member Jens Rasmussen did some nice Leach amp clone PCB's that you should checkout:
DELTA AUDIO - Leach Amp Clone
diy member Jens Rasmussen did some nice Leach amp clone PCB's that you should checkout:
DELTA AUDIO - Leach Amp Clone
Do not be afraid of building the Leach Amp, the build is easy if you take your time and do it right. For you intended purpose I think a 500VA transformer and 15000uf per channel will do just fine. I am a newbie like you and did something more ambitious, I build not two, but 6-channel all original board and components Leach Amp 4.5v and if I did it, I am very sure you could also do. As others already stated, there is plenty of information in this forum and others in case you run into problems. Since you plan to do your own boards, I recommend you modify the connectors to the power transistors, that is, plan for some quick connectors or something like that so that it will be easy to unplug everything if needed. I managed to incorporate quick connectors to mine and it made it very easy to unplug everything when I needed to do repairs due to a mistake I did.
Good luck with your build and just enjoy doing it and you will be happy with the results.
Good luck with your build and just enjoy doing it and you will be happy with the results.
The protection circuit in the Leach best be removed if u want still better sound. But then u have to use external speaker protection circuit if u wish to protect your (if) costly speakers. However on removing the internal protection, more semis will be blown. But then they r cheap and will happen over years of use.
If u use the external speaker protection, then u can increase the on-board filter electrolytics to a higher value like 1000µF instead of the 100µF.
Gajanan Phadte
If u use the external speaker protection, then u can increase the on-board filter electrolytics to a higher value like 1000µF instead of the 100µF.
Gajanan Phadte
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