Geoff's JLH PCBs
I've just finished a prototype of a JLH using Geoff's PCB layouts (thanks, Geoff!). This is a temporary setup while I decide on final packaging.
Here's a populated board. Notice it's single-sided, and only one wire link is needed. This is an easy board to stuff, I'd recommend this project to beginners except for the heatsinking and power supply requirements make it a fairly involved project.
I've just finished a prototype of a JLH using Geoff's PCB layouts (thanks, Geoff!). This is a temporary setup while I decide on final packaging.
Here's a populated board. Notice it's single-sided, and only one wire link is needed. This is an easy board to stuff, I'd recommend this project to beginners except for the heatsinking and power supply requirements make it a fairly involved project.
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Re: Re: Geoff's JLH PCBs
The power supply is almost 100% recycled parts. The transformers came from a pair of Advent Powered Loudspeakers (that are currently UnPowered); To get the proper voltage, I wired their primaries in series and their secondaries in parallel via the 10W current sharing resistors. I was originally going to add a capacitance multiplier but with the big capacitors I have Geoff suggested it was good enough without. Also, I didn't want to suffer the voltage drop and lower the rail voltages any further.
If I use this for the final arrangement, and it goes somewhere other than my lab, I'll have to hide it away (I've been told).
I think I might just keep it in the lab, though...
The power supply is almost 100% recycled parts. The transformers came from a pair of Advent Powered Loudspeakers (that are currently UnPowered); To get the proper voltage, I wired their primaries in series and their secondaries in parallel via the 10W current sharing resistors. I was originally going to add a capacitance multiplier but with the big capacitors I have Geoff suggested it was good enough without. Also, I didn't want to suffer the voltage drop and lower the rail voltages any further.
If I use this for the final arrangement, and it goes somewhere other than my lab, I'll have to hide it away (I've been told).
I think I might just keep it in the lab, though...
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J-amp 2003..
My 2 J-amp-2003's are still in use on a daily basis.
I've not even measured the actual DC-offset for the last year.
Probably a check might be nice.
They still have an audible ''thumb'' at power on. but i don't care.
Soundwise I'm still impressed with the fine combination of the J-amp 2003 and my JMLab Symbol II's.
My 2 J-amp-2003's are still in use on a daily basis.
I've not even measured the actual DC-offset for the last year.
Probably a check might be nice.
They still have an audible ''thumb'' at power on. but i don't care.
Soundwise I'm still impressed with the fine combination of the J-amp 2003 and my JMLab Symbol II's.
> Have you build this amplifier since?
Yes, using 8x MJ21194 per channel. +/- 15V, Total bias 5.6A. Gives you roughly 40W at 4 Ohm & 8 Ohm. Peaks at 6 Ohm.
Photo too large to post here. No housing yet. Just on heatsinks.
Try it for yourself. It won't take too much effort. Use a lab supply to see if you like it first before the big investment.
Thank you for your interest,
Patrick
Yes, using 8x MJ21194 per channel. +/- 15V, Total bias 5.6A. Gives you roughly 40W at 4 Ohm & 8 Ohm. Peaks at 6 Ohm.
Photo too large to post here. No housing yet. Just on heatsinks.
Try it for yourself. It won't take too much effort. Use a lab supply to see if you like it first before the big investment.
Thank you for your interest,
Patrick
Just managed to get it down to below 100kB.
Picture quality is horrible, but not much I can do.
This is one channel which is bolted onto a heatsink of 0.2K/W.
Circuit as posted except for the output transistors, as already mentioned.
Everything matched.
Patrick
Picture quality is horrible, but not much I can do.
This is one channel which is bolted onto a heatsink of 0.2K/W.
Circuit as posted except for the output transistors, as already mentioned.
Everything matched.
Patrick
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> it is possible to use BC560, MJL driver and MJL 3281 ?
Have not tried, so better not comment. But please have a look through Geoff's JLH website for alternative transistors.
You can get the Toshiba transistors at Fibra Brandt (near the French border), and MJ15003 from Reichelt.de (On Semi, 2.35 Euros each). Alternatively, order samples from the On Semi website. Don't order Japanese transistors from Reichelt. They are anything but original Toshiba / Hitachi, except for some Power FETs.
Patrick
Have not tried, so better not comment. But please have a look through Geoff's JLH website for alternative transistors.
You can get the Toshiba transistors at Fibra Brandt (near the French border), and MJ15003 from Reichelt.de (On Semi, 2.35 Euros each). Alternatively, order samples from the On Semi website. Don't order Japanese transistors from Reichelt. They are anything but original Toshiba / Hitachi, except for some Power FETs.
Patrick
