Monster amp
Decided some time ago to build "the ultimate" Single Ended class A power amp and really liked all I read about BBA-3 and BA-1 (and I already liked the sound of my Pass Labs Aleph 3)
Also wanted decent current capacity (running electrostatic speakers) and more than 25W of output power, so I ended up with a Monster Amp. See enclosed pics of one channel. Total weight around 40 kg (1 channel)
6 deep IRFP240, fully balanced config, totalling 24 output MOSfets.
Bias 750 mA/FET, all together 9 Amps.
20x2 V; 1200 VA toroid from toroidy.pl, 2 CL-60 in series (230 V input).
CRC-filter with 6x47 mF and 2 Dale 0,47 ohm in parallel.
Dual Schottky diode bridges with snubbers.
Final DC 2x22.4 V.
The monster gets hot (57 deg. C on top of external sinks, 63 deg. C on diode heat sinks at ambient 20 deg. C). Plan to build a 'fan box' sitting under each box to get the inside temp down a bit and improve convection for external heat sinks. Produces almost 500 W of heat.....
Phew!! Took more effort than expected, but the sound quality (!!!!) makes it
very worthwhile to start on the second channel. IMHO and subjectively it surpasses all A, B and K-amps I heard.
Mats
Decided some time ago to build "the ultimate" Single Ended class A power amp and really liked all I read about BBA-3 and BA-1 (and I already liked the sound of my Pass Labs Aleph 3)
Also wanted decent current capacity (running electrostatic speakers) and more than 25W of output power, so I ended up with a Monster Amp. See enclosed pics of one channel. Total weight around 40 kg (1 channel)
6 deep IRFP240, fully balanced config, totalling 24 output MOSfets.
Bias 750 mA/FET, all together 9 Amps.
20x2 V; 1200 VA toroid from toroidy.pl, 2 CL-60 in series (230 V input).
CRC-filter with 6x47 mF and 2 Dale 0,47 ohm in parallel.
Dual Schottky diode bridges with snubbers.
Final DC 2x22.4 V.
The monster gets hot (57 deg. C on top of external sinks, 63 deg. C on diode heat sinks at ambient 20 deg. C). Plan to build a 'fan box' sitting under each box to get the inside temp down a bit and improve convection for external heat sinks. Produces almost 500 W of heat.....
Phew!! Took more effort than expected, but the sound quality (!!!!) makes it
very worthwhile to start on the second channel. IMHO and subjectively it surpasses all A, B and K-amps I heard.
Mats
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finally gave my ACA a slightly better home. I got the correct heatsinks from the store and drilled and tapped them then just needed a place to mount them.
Cleaning out the garage I found a chunk of oak and then added thinner panels to the front and back.
It still needs some filling and sanding though.
Cleaning out the garage I found a chunk of oak and then added thinner panels to the front and back.
It still needs some filling and sanding though.
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Thanks for the nice words.
6L6 - you are absolutely right, it is BA3 (balanced i.e BBA3) running 2 'bridged' BA-1's (driving Quad 2912s)
Used point-to-point wiring to distribute heat better along the full length of the heat sink (works really well). Also the (DIY-style and a bit over-engineered
)copper star ground seems to be doing its job -- no hum at all.
My choice of diodes (ON Semi MBR40250G) was probably not the best --- losing 2,5 V over bridges per rail so lots of heat from the diode heat sinks inside the box. (Measured 70 deg C on the diode heat sinks today after 2 hrs of listening)
Like to try to replace it with STMicroelectronics STPS30M60ST (data sheet claims VF=0,38 V at 15 A forward current) ...but really happy for advice and experience from you hot amp builders here...cool (cooler) running discrete diodes in TO220 or TO247 packaging would be nice.
Will start building 2nd channel very soon now.
6L6 - you are absolutely right, it is BA3 (balanced i.e BBA3) running 2 'bridged' BA-1's (driving Quad 2912s)
Used point-to-point wiring to distribute heat better along the full length of the heat sink (works really well). Also the (DIY-style and a bit over-engineered
)copper star ground seems to be doing its job -- no hum at all.My choice of diodes (ON Semi MBR40250G) was probably not the best --- losing 2,5 V over bridges per rail so lots of heat from the diode heat sinks inside the box. (Measured 70 deg C on the diode heat sinks today after 2 hrs of listening)
Like to try to replace it with STMicroelectronics STPS30M60ST (data sheet claims VF=0,38 V at 15 A forward current) ...but really happy for advice and experience from you hot amp builders here...cool (cooler) running discrete diodes in TO220 or TO247 packaging would be nice.
Will start building 2nd channel very soon now.
Yes I have got the same error message. Solution-just press upload after adding each pic.
nash
My Pearl Two / B1 combo with PGA 2310 volume control. Control of 2310 is Ardiuno based. Remote control from Apple remote. Transformers for analog and digital part outside main enclosure in their own case mounted on the back panel.
Power supply B1 (line) part based on schematics by ZenMod parallel regulator posted somwhere here (thanks ZenMod!)
And, this is my ACA:
Power supply B1 (line) part based on schematics by ZenMod parallel regulator posted somwhere here (thanks ZenMod!)
And, this is my ACA: