finished my amp, its a LJM L25 amplifier board with 300VA 50+50 transformer and 8 x 5600uF 100V capacitors.
there is a Rod Elliot soft start & speaker protector. 12VDC comes from a downlight PSU.
case is a mnix of 3mm aluminium (covered in 4D vinyl wrap that they use for cars) and "DVA One Way Vision Mesh" that is used on security doors (i had it laying around after suing it as leaf guard on gutters)
there is a vishay cermet pot for the volume, but it is a sub woofer amp, so leave it at full volume and control levels with receiver.
it's doing its sub woofer duties nicely. haven't tried it as a full-rage amplifier yet...
there is a Rod Elliot soft start & speaker protector. 12VDC comes from a downlight PSU.
case is a mnix of 3mm aluminium (covered in 4D vinyl wrap that they use for cars) and "DVA One Way Vision Mesh" that is used on security doors (i had it laying around after suing it as leaf guard on gutters)
there is a vishay cermet pot for the volume, but it is a sub woofer amp, so leave it at full volume and control levels with receiver.
it's doing its sub woofer duties nicely. haven't tried it as a full-rage amplifier yet...
Attachments
Sajti, Very nice and clean as always. will you attach heatsinks to the back panel or it's some kind of class B amp?
...7 year project
I'm enjoying it in combination with a bluesound streamer each day. Even my wife likes it (most scrarefull thing from the entire project)!!!
Some specs:
- PSU output stage: 1KVA 2X36V (2X52VDC), hexfred diodes and CLC (C=22000µF Vishay 106PED series)
- Driver section: has an extra 4R7 + 10000µF RC combination on top.
- PSU front end: 50VA + cap multiplier (2X61VDC)
- Front end:
- input jfet's 2SK389+2SJ109 cascoded with 2SK216 + 2SJ79, biased at 6mA
- VAS mosfets: IRF710 + IRF9610 biased at 25mA
- takman REX resisters and charcroft Z-foil feedback resistor
- Output stage:
- 7pair 2SA1386/2SC3519 matched Sanken bjt's, biased at 105mA with 0.5% 0R22 Dale emitter resistors
- 2SK1530 + 2SJ201 mosfet driver, biased at 110mA.
- 12Wrms class A into 8R
- 150Wrms into 8R. And capable of easily driving 2Ohm loads.
- Solid state speaker protection based on TA7317P IC
- controller board with soft start, power on push button over-temperature detection circuitry
- dimensions: W450mm x H220mmx D420mm
- Weight: around 20kg each
- both amps are connected with each other via a 3.5mm jack. With one push button I can switch on and off both amps. For switching on, one has to push the button for about 4seconds (child protection
to not burn the soft start resistors.)
More to find: 2nd amp from scratch: Low NFB- FET front end - BJT OPS
Thanks to all here!!
I'm enjoying it in combination with a bluesound streamer each day. Even my wife likes it (most scrarefull thing from the entire project)!!!
Some specs:
- PSU output stage: 1KVA 2X36V (2X52VDC), hexfred diodes and CLC (C=22000µF Vishay 106PED series)
- Driver section: has an extra 4R7 + 10000µF RC combination on top.
- PSU front end: 50VA + cap multiplier (2X61VDC)
- Front end:
- input jfet's 2SK389+2SJ109 cascoded with 2SK216 + 2SJ79, biased at 6mA
- VAS mosfets: IRF710 + IRF9610 biased at 25mA
- takman REX resisters and charcroft Z-foil feedback resistor
- Output stage:
- 7pair 2SA1386/2SC3519 matched Sanken bjt's, biased at 105mA with 0.5% 0R22 Dale emitter resistors
- 2SK1530 + 2SJ201 mosfet driver, biased at 110mA.
- 12Wrms class A into 8R
- 150Wrms into 8R. And capable of easily driving 2Ohm loads.
- Solid state speaker protection based on TA7317P IC
- controller board with soft start, power on push button over-temperature detection circuitry
- dimensions: W450mm x H220mmx D420mm
- Weight: around 20kg each
- both amps are connected with each other via a 3.5mm jack. With one push button I can switch on and off both amps. For switching on, one has to push the button for about 4seconds (child protection
to not burn the soft start resistors.)
More to find: 2nd amp from scratch: Low NFB- FET front end - BJT OPS
Thanks to all here!!
Attachments
Last edited:
The 3mm back panel has cutout, and the output devices mounted directly to the heatsink. Class AB with 70mA bias on each output devices.
Sajti
Very nice Ben,
Also you have your speakers , time for me to come over and listen
Just say when , I'm home the whole coming week (hint) .
Last edited:
thanks (i think), i certainly didn't 'copy' anyone else's project - that's for sure
but working fine and wife has accepted it's mantel atop the subwoofer now, so all's well!
My last super release (of the 7/8 released
in the last 15 years) of the NAIM H140 clone:- Power supply soft-start circuit,
- Power supply circuit with two-stage RF suppressor,
- Dual-mono stabilised power supply stage for "differential input stage" and "pilot stage",
- BJT linear power supply stage of low impedance dual-mono type with 4 fast double-diodes for each channel and total filtering capacity 84,000 uF,
- 600VA audio-grade toroidal transformer,
- NAIM 140 clone with circuit type in Class "AB" with "almost complementary" Darlington (Rail positive) + Sziklai (Rail negative) configuration,
- DC voltage protection on the output speaker terminals,
- Continuous power output x 2: 110 Watt on 8 Ohm - 190 Watt on 4 Ohm
- Maximum power output on 10 mS burst and loads up to a minimum of 2 Ohm: 320 Watt per channel
- Bandwidth: 120,000 Hertz / -3 dB
- Input impedance: 18K Ohm
(Detail of amplification PCBs mounted under the heatsink)
Last edited:
Thank you for your excellent advice.
Although I must admit that the fans of the thermostated forced ventilation system (activation threshold at 55 degrees Celsius detected on the heatsink) shown in the picture, even though they are of computer-derived derivation on a low noise fluid-dynamic support, are really very silent.
Although I must admit that the fans of the thermostated forced ventilation system (activation threshold at 55 degrees Celsius detected on the heatsink) shown in the picture, even though they are of computer-derived derivation on a low noise fluid-dynamic support, are really very silent.
Last edited:
Thank you.
And I would also like to take this opportunity to congratulate @Bensen on the excellent engineering that I personally appreciate so much.
When "cleanliness" and aesthetics of the realization, they stop being something ephemeral and become functional of the realization.
Hi Ultima, very good job indeed
BTW, where did you buy this kind of chassis?
Cheers,
Valery
Hi Ultima, very good job indeed
BTW, where did you buy this kind of chassis?
Cheers,
Valery
Hello Valery,
with a touch of Italian pride, the company is Italian and has been operating in the specific sector of cabinets for electronic use for more than 40 years: HIFI-2000.
Among other things, besides producing cabinets of different heights and depths and with "dissipating" sides, it also ships abroad without any particular problems.
Pino.
My implementation of Bonsai OVATION NX-AMPLIFIER: A high performance 100 W Class AB Current feedback amplifier
Attachments
