Hello all,
Today is a glorious day! The paintwork for my amplifier is done, and I am finally ready to assemble my Aleph 2 monoblocks. All pre-assembly and component gathering was done in the past 4 years, so in this weekend I expect to have two huge amplifiers rising....
For bringing up the appetite, below is the first picture of the platework just brought in... It is painted in a BMW metallic paint
Some specs:
- 1 kVA toroid transformer, 2x 42V / 11,9A secondaries.
- More than 198.000 uF capacitance on each rail
- Nominal rail voltage +/- 55V, 10mV ripple under 500W load.
- Bias current 0,5A on each fet pair, times 6 = 3A bias
- 330W dissipation per channel.
Apart from exaggerating on the power supply, the amplifier design is practically unaltered from the original Pass design.
First, I'm off to a cigar & whiskey tasting event... Tomorrow the big build will start....
Cheers!
Bakmeel
Today is a glorious day! The paintwork for my amplifier is done, and I am finally ready to assemble my Aleph 2 monoblocks. All pre-assembly and component gathering was done in the past 4 years, so in this weekend I expect to have two huge amplifiers rising....
For bringing up the appetite, below is the first picture of the platework just brought in... It is painted in a BMW metallic paint
Some specs:
- 1 kVA toroid transformer, 2x 42V / 11,9A secondaries.
- More than 198.000 uF capacitance on each rail
- Nominal rail voltage +/- 55V, 10mV ripple under 500W load.
- Bias current 0,5A on each fet pair, times 6 = 3A bias
- 330W dissipation per channel.
Apart from exaggerating on the power supply, the amplifier design is practically unaltered from the original Pass design.
First, I'm off to a cigar & whiskey tasting event... Tomorrow the big build will start....
Cheers!
Bakmeel
Attachments
Goodafternoon y'all!
So here we go... All housekeeping tasks (groceries, laundry, etc) are now done, we can start...
First step is to mount the mainsboard on the baseplate. The baseplate is 10mm thick hardened aluminium.
The mainsboard contains a small auxiliary power supply and two large relais for the soft-start circuit I've alredy posted on this forum here
So here we go... All housekeeping tasks (groceries, laundry, etc) are now done, we can start...
First step is to mount the mainsboard on the baseplate. The baseplate is 10mm thick hardened aluminium.
The mainsboard contains a small auxiliary power supply and two large relais for the soft-start circuit I've alredy posted on this forum here
Attachments
Adding weight
Next part is the transformer and rectifier assembly.
The transformer is an Amplimo type Z8022 toroid. Amplimo also sells transformer pots, but they are normally used for tube amplifier transformers. A friend of mine potted it using a kind of soft potting material, also used for potting in-road LED lighting.
The two rectifiers are made with International Rectifer 63CPQ100 schottky diodes. They are mounted on 4mm thick ceramic plates for thermal coupling.
Next part is the transformer and rectifier assembly.
The transformer is an Amplimo type Z8022 toroid. Amplimo also sells transformer pots, but they are normally used for tube amplifier transformers. A friend of mine potted it using a kind of soft potting material, also used for potting in-road LED lighting.
The two rectifiers are made with International Rectifer 63CPQ100 schottky diodes. They are mounted on 4mm thick ceramic plates for thermal coupling.
Attachments
Bijna klaar Bouke?
Ziet er mooi uit allemaal.
Looks great spacy.
Heb je mijn nieuwe boxes al gezien?nieuwe boxjes
Ziet er mooi uit allemaal.
Looks great spacy. Heb je mijn nieuwe boxes al gezien?nieuwe boxjes
Heej Helmuth,
Speakertjes zien er puik uit! Mooi afgewerkt!
Next mount is the primary capacitor bank. 2 x 4 x 33.000uF / 63V Vishay BC Components. Copper strips to connect the lot together.
The primary capacitor bank is part of a CLC filter combination. More on the filter next post.
I've wired the capacitors in a kind of X- wiring. The current paths through the copper strips cross one another such that the impedance seen on each capacitor is identical, and they all filter an equal share of the ripple current.
Speakertjes zien er puik uit! Mooi afgewerkt!
Next mount is the primary capacitor bank. 2 x 4 x 33.000uF / 63V Vishay BC Components. Copper strips to connect the lot together.
The primary capacitor bank is part of a CLC filter combination. More on the filter next post.
I've wired the capacitors in a kind of X- wiring. The current paths through the copper strips cross one another such that the impedance seen on each capacitor is identical, and they all filter an equal share of the ripple current.
Attachments
This is me wiring up the second stage of the CLC filter.
Since the A2 draws - like all other Alephs - a constant current under most conditions (neglecting the low-frequency modulation in the current source) I thought I could best use a CLC combination and put the filter frequency as low as possibl , the filter sizes: 132mF - 3mH - 66mF. Actually I've never calculated the filter frequencies, but
Duncan's Amp PSU Designer tool was all to handy, and I trust that it is accurate enough.
Behind the large inductor - there is another large inductor! The two air-core inductors are placed back-to-back, putting them in a sort of magnetic coupling through air (and plastic). In essence, this makes them a weakly coupled DC common mode filter. I've never tested its benefit, but if the physics still work, there should be some good in it, shouldn't there? 
Since the A2 draws - like all other Alephs - a constant current under most conditions (neglecting the low-frequency modulation in the current source) I thought I could best use a CLC combination and put the filter frequency as low as possibl , the filter sizes: 132mF - 3mH - 66mF. Actually I've never calculated the filter frequencies, but
Duncan's Amp PSU Designer tool was all to handy, and I trust that it is accurate enough.
Behind the large inductor - there is another large inductor!
The two air-core inductors are placed back-to-back, putting them in a sort of magnetic coupling through air (and plastic). In essence, this makes them a weakly coupled DC common mode filter. I've never tested its benefit, but if the physics still work, there should be some good in it, shouldn't there? Attachments
steenoe said:
Holy Canoly. Heavy metal
BTW
Didn't I mention in the beginning I exaggerated a bit on the power supply?
Maybe I went a bit over the top, but I remember one of our fellow Pass Forumers to say "If more is better, than too much is just enough"...
Indeed, I've taken a lot precautions not to make any shorts... The equivalent energy stored in these caps when operation (55V) is enough to make a shot of water (about 3 cl) boil instantly....
This is part of that precaution: The soft-start control circuit (see third post)
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I have treated the copper sides of all PCB's with Conformal Coating to protect them against corrosion and dust.
A small exception is made where I've planned an electrical contact with crimp lugs, such as the power supply connections on the Front End PCB (the rightmost part is not coated)
A small exception is made where I've planned an electrical contact with crimp lugs, such as the power supply connections on the Front End PCB (the rightmost part is not coated)
Attachments
And so, the Front End PCB is married with the structure and the power supply.
The big power supply cables are bolted to the copper traces with lugs. The two small white wires are the connection to mains ground. There is a small relay on the mains PCB where the ground can be lifted if one would need to eliminate a ground loop.
With this approach, the all so important star ground pount is exactly at the speaker return point.
The big power supply cables are bolted to the copper traces with lugs. The two small white wires are the connection to mains ground. There is a small relay on the mains PCB where the ground can be lifted if one would need to eliminate a ground loop.
With this approach, the all so important star ground pount is exactly at the speaker return point.
Attachments
- Status
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