hi kwikas,
That looks suitable, using the two isolated secondaries.
I guess you appreciate that as the smoothed DC output from a bridge rectifier into say a 10,000uF will give approx 45Vdc, rather than the required 55V.
This will reduce the maximum power output from the amps.

Lets know how it goes.
BTW: did you read the terminal block coding on the cap/rectifier PCBs.???

E

EDIT:
OK, will look out for your PCB post.

 

Hi Eric,

I still need to get the PCB out from storage but will get to in a day or so and let you know how the blocks are marked. Tks

Andrew

 

The DC plus and minus 47V will reduce to audio peaks of about plus and minus 45V. Then the 90V p-p produces 31.8V RMS which is 126W into an 8 ohms load. The amplifiers look to be class-AB so they produce heating of 100W each.
Then the total from the transformer is (126W + 100W) x 6= 1356VA.

You never play a continuous tone on all 6 channels at the same time so I would use a 1000VA transformer.
How will you prevent damage to your speakers, windows and your hearing??

 

The DC plus and minus 47V will reduce to audio peaks of about plus and minus 45V. Then the 90V p-p produces 31.8V RMS which is 126W into an 8 ohms load. The amplifiers look to be class-AB so they produce heating of 100W each.
Then the total from the transformer is (126W + 100W) x 6= 1356VA.

You never play a continuous tone on all 6 channels at the same time so I would use a 1000VA transformer.
How will you prevent damage to your speakers, windows and your hearing??

Thanks for the info. I was considering to use both of my 625VA toroids to drive 3 amplifier boards off each. I will have to buy another power board to do this but that's no problem.

You raise valid concerns though...

 

How will you cool the amplifier boards? The angle aluminum is much too small to be a 100W heatsink so it must have a real finned heatsink connected to it for each amp board.

What is the "power board" that you must buy? With a heatsinked bridge rectifier and two huge filter capacitors on it?

 

hi Ag,
Its this one.
I have asked the TS for the coding on the terminal blocks, he is going to post.
E
https://www.ebay.com.au/itm/Assembl...590425?hash=item1c490bbd59:g:INUAAOSw~1FUUyVf

 

That power supply board is a cheap Chinese joke. 68 little capacitors? But the total capacitance is barely enough for an audio amplifier to produce powerful low frequency bass sounds.
Are you guessing and hoping that it has plus and minus inputs and outputs?

 

The DC plus and minus 47V will reduce to audio peaks of about plus and minus 45V. Then the 90V p-p produces 31.8V RMS which is 126W into an 8 ohms load. The amplifiers look to be class-AB so they produce heating of 100W each.
Then the total from the transformer is (126W + 100W) x 6= 1356VA.

You never play a continuous tone on all 6 channels at the same time so I would use a 1000VA transformer.
How will you prevent damage to your speakers, windows and your hearing??

Yes, I have the finned heatsinks but I am going to fan cool these because everything will be in an enclosed case...

 

Yes, I have the finned heatsinks but I am going to fan cool these because everything will be in an enclosed case...

Have the fan mounted on the case, drawing air into the box, with the air then blowing directly on the heatsink(s) and , of course, you will need a way for the air to get out of the box again. That way of directing the air will get you the most cooling effect.

Many years ago, I was repairing a large power supply. It was new and being repaired under warranty. The heatsink was getting too hot and so it would only run for a while before the thermal protection shut it down. After lots of measuring I couldn't see any fault then I realised that the fan was blowing outwards from the case. They had fitted it the wrong way round in the factory.

 

Have the fan mounted on the case, drawing air into the box, with the air then blowing directly on the heatsink(s) and , of course, you will need a way for the air to get out of the box again. That way of directing the air will get you the most cooling effect.

Many years ago, I was repairing a large power supply. It was new and being repaired under warranty. The heatsink was getting too hot and so it would only run for a while before the thermal protection shut it down. After lots of measuring I couldn't see any fault then I realised that the fan was blowing outwards from the case. They had fitted it the wrong way round in the factory.

Hi Albert. I used pro amps (EV Q66's) for quite a while in my my previous home theatre room. They were kept in a rack outside the room because of the fan noise (as this amp will be) and they performed flawlessly. My current sub amps are all pro amps (Ecler DPA 2000's - bridged mono) with fan air flow that draws from the back to the front. My idea with this 6 channel amp is to air flow it the same way and then I can vent the hot air from all amps out of the top front of the cabinet.

I have a Silverstone LC17 home theatre case that I can repurpose for this build. It has a large air intake vent at the front and the fans are mounted on the back. I'm going to completely rebuild the back of the chassis though....it doesn't really work for me in this project.

 

Ok, so AG has advised that the PSB is sub standard for this build. I'll look to getting something better/beefier to handle 3 amplifiers.

In the meantime, I need to do some 'remodelling' of the LC17 case because it wont fit 6 amp boards longitudinally. It will currently only fit 4 of them (2 on each side) so I need to lengthen it.....not a small job :-(

Eric, I am quite settled on using the 2 x 625VA toroids I currently have for this build but a 1500VA with dual secondaries has just come onto the market down here. The secondaries are 53 0 53 @ 230V and 55 0 55 @ 240V. That's a better match to the amps and I could run all 6 boards off of it...???

 

The amplifiers are powered with plus and minus 55VDC, not 55VAC from a transformer. 53VAC has a peak of 75V and the rectifiers and large filter capacitors drop it to 73V which is way too high. 55VAC produces an even higher DC voltage (almost 76VDC).

If you cram 4 or 6 amplifiers into a case then how will you cool them? The angled metal is too small and needs to be bolted to a real heatsink with many large fins (each amplifier heats with about 105W) and the heatsinks must not be enclosed unless the enclosure has open ends and a fan.

 

Tks AG and noted re VAC to VDC (x 1.414).....

With regard to heatsinks, I am going to use aluminium heat sinks that have a fan at the end of them. The fan screws into the end of the extrusion to draw air along it.

In order to fit in all 6 amplifier boards, the case will have to be lengthened. The case I am using has vents at the front and the back of it....