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Old 31st July 2013, 02:53 AM   #421
6L6 is offline 6L6  United States
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Total.

Of course, a bigger transformer is better, but the Firstwatt amps are almost all 300VA.

If Nelson uses it, it's obviously enough.
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Old 31st July 2013, 03:46 AM   #422
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300 VA will be sufficient, but per channel. At least get 250 VA per channel or 500 VA stereo.
I went for 500 VA each.

Even more important: Get enough capacitance. Lots of it. This is class A and class A draws
lots of current and lots of current means high ripple. Even when you listen to 'silent' music.
So buy the biggest lytics you can afford and consider to build it CLC, CRCLC or at least CRC.
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Old 31st July 2013, 04:12 AM   #423
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Quote:
Originally Posted by ticktock View Post
300 VA will be sufficient, but per channel.
300VA is quite sufficient for a stereo amp.

The Aleph is single-ended. You can't have more output than your bias, but SE (in)efficiencies play into output power as well... Reducing it.

The big transistors are biased at approximately 20W each. There are (8) in an stereo amp. 8 x 20 = 160W

VA is roughly equal to Watts. So how can a 300W transformer be too small for a circuit that draws just a bit more than 160W?

That said, bigger transformers are nice. (Make them too big,however, and they start buzzing if you have traces of DC on your AC line...)

Your comments about PSU capacitance and filtering are right on.
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Old 31st July 2013, 08:35 AM   #424
biju55 is online now biju55  India
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Nelson uses Plitron High End transformers in his first watt products
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Old 31st July 2013, 11:20 AM   #425
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Quote:
Originally Posted by 6L6 View Post
300VA is quite sufficient for a stereo amp.
The Aleph is single-ended. You can't have more output than your bias, but SE (in)efficiencies play into output power as well... Reducing it.
The big transistors are biased at approximately 20W each. There are (8) in an stereo amp. 8 x 20 = 160W
VA is roughly equal to Watts. So how can a 300W transformer be too small for a circuit that draws just a bit more than 160W? ...
First, I should mention, the Aleph CCS design is capable of outputing more than the bias!
And, you can never read enough Pass I guess. From the BA1 article, which is not an Aleph CCS design but, is SE: "As the typical Burning Amp will dissipate more than 300 watts, the transformer wants to be rated at least twice that."
Having read that, I would say you would want at least 320VA, if not more?
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Old 31st July 2013, 01:20 PM   #426
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Quote:
Originally Posted by flg View Post
the Aleph CCS design is capable of outputting more than the bias!
More than the bias of the Output devices and the CCS devices? Think about that...

Quote:
And, you can never read enough Pass I guess.
I completely agree.

Quote:
From the BA1 article, which is not an Aleph CCS design but, is SE: "As the typical Burning Amp will dissipate more than 300 watts, the transformer wants to be rated at least twice that."
Having read that, I would say you would want at least 320VA, if not more?
You are completely correct. It's not that a bigger transformer is bad, not at all... as I personally am building mine with 400VA.
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Old 31st July 2013, 04:56 PM   #427
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Quote:
Originally Posted by 6L6 View Post
More than the bias of the Output devices and the CCS devices? Think about that...
The Aleph CCS has an "AC Gain" function, typically set to about 50%. Allowing for 50% more current than the Iq. The Aleph J however, I believe is set to a lower AC gain figure.
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Old 31st July 2013, 05:22 PM   #428
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Both you're right, mates.

It all depends on the money one is able to spend, but let us agree in that on an Aleph J,
PSU capacitance and filtering is much more important than the transformer's VA rating.
BTW, I'd rate two 200 VA transformers over one single 500 VA. It wil, measure better and
it will sound better.

Nevertheless I went for two 500 VA toroidals (as this will make the PSU more universal
for future projects). The only downside besides cost is the inrush current, which makes
the need for a soft start or at least for an NTC, of course the first one being better.

I'd greatly recommend to go for a set of four decent inductors and some, say 0.5 R resis-
tors and go the CRCLC route or similar. Some of you may find some old speaker crossover
inductors in your spare box. Of course you need 4 identicals ones for a stereo amp if you
want two seperate PSUs (which I would prefer).
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Old 31st July 2013, 09:02 PM   #429
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Talking Excellent News - Boards Arrived!

And boy are they pretty!

So now a few questions.

1. Are we going to use this thread for build discussion?
2. How's the build guide coming along? (hint, hint);-)
3. Would anyone like to discuss their preferred component choices as compared to the basic BOM? I would love to learn more and get some ideas.
4. I'm thinking about building mine BLAT style (liquid cooling). Are there others on that path, or am I the usual outlier?

Finally, I just ordered 2SJ74BL's from Spencer at FET Audio. He still has more available. With shipping for 4 to the US and Paypal fees, they cost $8.71 each. I'll let you make the cost/benefit decision.
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Old 31st July 2013, 09:43 PM   #430
henryve is offline henryve  South Africa
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Quote:
Originally Posted by lehmanhill View Post
And boy are they pretty!

So now a few questions.

1. Are we going to use this thread for build discussion?
2. How's the build guide coming along? (hint, hint);-)
3. Would anyone like to discuss their preferred component choices as compared to the basic BOM? I would love to learn more and get some ideas.
4. I'm thinking about building mine BLAT style (liquid cooling). Are there others on that path, or am I the usual outlier?

Finally, I just ordered 2SJ74BL's from Spencer at FET Audio. He still has more available. With shipping for 4 to the US and Paypal fees, they cost $8.71 each. I'll let you make the cost/benefit decision.
Hey, spare a thought for us living out here in the sticks! I might only get mine in another 3 weeks.
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