I just finished my J clone. Sounds so good, after 50h burning even better then Firstwatt F7 :O
Specification
Power Supply:
True Dual Mono Design
Furutech Gold Plated IEC Inlet
Relay softstart with 4s delay
2 x 250 VA for audio purpose (22-0-22 V) from Toroidy.pl
Two 35 A bridges
4 x CRCC: 82000 uF - 1 ohm 50 W - 82000 uF - Wima MKP 1 uF
All PS connections via 1,5 mm2 solid copper wire
Audio board:
PCB's from Diyaudio
R16-R19 Panasonic ERX
R20-R23 First was ERX but replaced with one 0,11 Ohm 15W DIY made in Poland graphite resistor (like Pathaudio or Duelund but 4 times cheaper).
Other resistors are PRP PR9372
C1,C6,C7 Mundorf MCap Supreme
C2,C3,C4 Elna Silmic II
JFET's IDSS 7.75 quad matched
Q2-Q4 Matched between channels
Q5-Q8 Matched IRFP240 between pairs and channels with thin kapton pads
Chassis & grounds:
The worst decision in my life
Chinese golden Dun Mei Audio s.h.i.t.
Need some more radiator mass, so I decided to add two PA38 (alu 6063) 30x10x2 cm blocks.
CMC copper RCA & speaker binding posts
Switchcraft XLR sockets
Input connected via DIY cable based on Cardas 23.5 and tinned copper shielding
Output connected via Oyaide Explorer
Speakers are protected by relay with 8s delay after turn on
Two 80x80 low noise fans
Grounds from each channel PSU are connected via cl-60 to chassis. Signal input grounds directly to chassis. Dead silence on my 99dB speakers.
Conditions after 1 hour:
PS Voltage on boards: +/- 27 V
Bias: 450 mV
Temperature: ambient 22*C, directly on transistors 60*C
Sound:
Tubelike sound with full of audiophile air, details, big soundstage - sound comes from everywhere, sweet midrange and smooth highs. Well controled bass.
Sound could be a little bit faster with drive, but this is not a AB class amp After switch to Firstwatt F7, something get weird, soundstage was gone, I only hear that sound "was glued to the speakers". Next I switched to big polish 80 W class A Abyssound ASX-2000 amp. Results was similar but with better and tougher bass.
Tested with:
GPA Altec 604-8H-III (250 liters enclosure)
Dynaudio Contour S 5.4
Krell KRC-3
Audio Research CD7 (upgraded PS from CD8)
Firstwatt F7
Abyssound ASX-2000
Audiomatus AM400
Soul Note SD300
Denon DNP-730 streamer (only for files transport)
Oyaide Pa-02 XLR cables
Fadel Art Coherence RCA cables
Purist Audio Poseidon speaker cables
Oyaide Explorer 2.0 speaker cables
Plans:
So, I am impressed with this amp and I think I will go soon with "guts" to new chassis, probably monoblocks to reduce some heat, and go higher with bias to about 500 mV. After good results with graphite resistors, I want to go this way also with R16-R19. Also wanna try some teflon caps like SCR FEP-SN or V-Cap's on C1,C6,C7. I think that could be a good choice
Pictures:
Not the newest configuration, without XLR's graphite resistors etc. but generally looks similar now
Specification
Power Supply:
True Dual Mono Design
Furutech Gold Plated IEC Inlet
Relay softstart with 4s delay
2 x 250 VA for audio purpose (22-0-22 V) from Toroidy.pl
Two 35 A bridges
4 x CRCC: 82000 uF - 1 ohm 50 W - 82000 uF - Wima MKP 1 uF
All PS connections via 1,5 mm2 solid copper wire
Audio board:
PCB's from Diyaudio
R16-R19 Panasonic ERX
R20-R23 First was ERX but replaced with one 0,11 Ohm 15W DIY made in Poland graphite resistor (like Pathaudio or Duelund but 4 times cheaper).
Other resistors are PRP PR9372
C1,C6,C7 Mundorf MCap Supreme
C2,C3,C4 Elna Silmic II
JFET's IDSS 7.75 quad matched
Q2-Q4 Matched between channels
Q5-Q8 Matched IRFP240 between pairs and channels with thin kapton pads
Chassis & grounds:
The worst decision in my life
Chinese golden Dun Mei Audio s.h.i.t.Need some more radiator mass, so I decided to add two PA38 (alu 6063) 30x10x2 cm blocks.
CMC copper RCA & speaker binding posts
Switchcraft XLR sockets
Input connected via DIY cable based on Cardas 23.5 and tinned copper shielding
Output connected via Oyaide Explorer
Speakers are protected by relay with 8s delay after turn on
Two 80x80 low noise fans
Grounds from each channel PSU are connected via cl-60 to chassis. Signal input grounds directly to chassis. Dead silence on my 99dB speakers.
Conditions after 1 hour:
PS Voltage on boards: +/- 27 V
Bias: 450 mV
Temperature: ambient 22*C, directly on transistors 60*C
Sound:
Tubelike sound with full of audiophile air, details, big soundstage - sound comes from everywhere, sweet midrange and smooth highs. Well controled bass.
Sound could be a little bit faster with drive, but this is not a AB class amp
After switch to Firstwatt F7, something get weird, soundstage was gone, I only hear that sound "was glued to the speakers". Next I switched to big polish 80 W class A Abyssound ASX-2000 amp. Results was similar but with better and tougher bass.Tested with:
GPA Altec 604-8H-III (250 liters enclosure)
Dynaudio Contour S 5.4
Krell KRC-3
Audio Research CD7 (upgraded PS from CD8)
Firstwatt F7
Abyssound ASX-2000
Audiomatus AM400
Soul Note SD300
Denon DNP-730 streamer (only for files transport)
Oyaide Pa-02 XLR cables
Fadel Art Coherence RCA cables
Purist Audio Poseidon speaker cables
Oyaide Explorer 2.0 speaker cables
Plans:
So, I am impressed with this amp and I think I will go soon with "guts" to new chassis, probably monoblocks to reduce some heat, and go higher with bias to about 500 mV. After good results with graphite resistors, I want to go this way also with R16-R19. Also wanna try some teflon caps like SCR FEP-SN or V-Cap's on C1,C6,C7. I think that could be a good choice
Pictures:
Not the newest configuration, without XLR's graphite resistors etc. but generally looks similar now
Yeah, the fitting was quite poor. I had so much trouble getting the lit
with the slight misalignment of holes. Fortunately I didn't cut myself but
mine definitely had a lot of sharp edges...
Dennis
Thanks Dennis, I was wondering how to safely get the lettering off the 2U chassis I got from them that I used for a preamp.
Couguarek: Very nice build. So you have 27 V rails. Did you change any other values from the standard Aleph J schematic?
Thanks
No. Only PS have some different, bigger values.
C6 & C7 are 0.33 uF
R20-R23 four resistors 0R47 was replaced by one 0R11 but this is overall the same value.
J1-J2 are 100R
R6 are 560R
R30 are jumper or smthg like 47R, I forgot
Take care to the (closest as possible) all component matching, also between channels, even if it's unnecessary. I belive this is the key to perfect sounding J
Also good quality components are necessary.P.S. If it's possible connect it via XLR to good, true symetrical preamp & source. Difference is realy huge