• These commercial threads are for private transactions. diyAudio.com provides these forums for the convenience of our members, but makes no warranty nor assumes any responsibility. We do not vet any members, use of this facility is at your own risk. Customers can post any issues in those threads as long as it is done in a civil manner. All diyAudio rules about conduct apply and will be enforced.

Jens Rasmussen Leach clone group buy

Jump to Latest
#261
Tad,
Which flavor of Leach Amp would you like to have boards for? Jens has made the Low TIM design boards with 6 and 10 output transistors. There is a schematic for the Double Barreled Leach Amp (schematic V2.7) posted by Jens) which has 16 outputs. The 6 transistor amplifier would be ideal for home theater and other general hi-fi use. The 10 transistor amp would handle low impedance loudspeakers and those requiring high voltage and high current.
The double barreled amplifier would provide very high power to high impedance speakers and probably be suitable for those who want very, very high power for subwoofer amplifiers. This amplifier would be warranted where very high output voltages have to be delivered to the load. It looks as though there are three distinct categories of application, which may be answered by the two Leach designs.
Regards, Harold
 
#262
I personnally like the 10 transistor version. You do not have to use 10 output transistors if you do not want to which gives some flexability in design.
I would very much like to build the super leach Jens version if and when a final board layout has been transferred to gerber file AND with permission from the designer of the board.
I have 4 boards assembled and ready to power up during the holidays. I hope all works out as planned.

The last group buy worked out without too much headache. I learned quite alot from that experience. I will post information about the GB in January after getting board quotes from Advanced Circuits. I do not believe I qualify for another 500.00 first time buyer discount. So the boards will probably be a few dollars more. Tad
 
#264
I haven't built a super Leach, but the cascodes throughout should change the high frequency open loop bandwidth for the better. Somebody along the way suggested that the super Leach sounds better than the low TIM version.

Rough costs should be $20 for a 10 output low TIM and $25 for double barrel due to the increased board size.
 
#265
i have built several of the double barreled amps, my first one in 1984, scaled down a bit using 63volt rails and japanese output trannies, and the last one in 2004 using original ON-semi parts for output.

those who heard my amps had simmilar comments, that is, the amp seems to deliver effortlessly, not tiring to listen to, even at high volume levels...😀

btw, i used a 4way speaker system with 15 in woofer, 12 in low mid, a dome for high mid, and series paralleled domes for highs on a 9cu feet baffles....
 
#266
BobEllis said:
I haven't built a super Leach, but the cascodes throughout should change the high frequency open loop bandwidth for the better. Somebody along the way suggested that the super Leach sounds better than the low TIM version.

Rough costs should be $20 for a 10 output low TIM and $25 for double barrel due to the increased board size.
Click to expand...


Ok, In that case I'll take two 10 transistor boards and two super leach boards.
I live in Croatia, do you know something about delivery cost?

And please, be so kind to give me link to super leach pcb.
Thanks
 
#267
Hi All,

Merry Christmas everyone.

I had some spare time during the last days, so I updated the 10 transistor board with some minor changes.

Changes are:
1) Better symmetry in layout.
2) Bigger rails (Now done with planes rather than tracks)
3) Feedback point moved (don’t know if this is needed but now Andrew will be happy)
4) Made better room for heat sinks on driver transistors
5) Changed small signal transistors to BC546/556

Let me know if you want PDFs and Gerbers of this.

\\\Jens
 
#270
Merry Christmas Jens

I would be very happy to run a GB for your new board design when you make the gerber files available.

Could you post a picture of the new layout.
There is also a few posts or threads related to Dr. Leach's choice of 4 bias diodes instead of using 3. I have very little knowledge in this area, however i would like to know if 3 diodes would provide better control. Some people think Dr. Leach used the forth diode to bring the units back for easier wiring. Tad

P.S. I hope Janni is doing well.
 
#277
Hi Jens,
yes, move the output to near the power inputs and the big smoothing/decoupling caps.

The long return route (ground) in the older PCBs leaves a big loop area that could usefully be very much smaller.
I think the two power feeds and the ground feed should be close coupled, the speaker out should be near those.
 
#279
tryonziess said:
It looks like we are on the road again for this GB. The thing I would like to know is if we can find a good deal on 100v power supply caps like Rifa or Sikorel. High capacitance electrolytics can kill a good budget. Anyone have a source for these. Tad
Click to expand...


Well, I am planning to power up my amp with SMPS. It should be easy.. For me, smaler capacitors would be good to!
 
#280
Jens, While you are asking for suggestions I was thinking that the resistor solder holes could be just a little bit larger. Some of the Vishay/Dale resistors have quite large leads and are TIGHT. This is probably too much trouble, but a suggestion.
When you had your original boards made which company did you choose to produce the boards? Tad
 
You must log in or register to reply here.
Top Bottom