Balanced ZenV4 again

I read all the articles (several times), followed this forum for quite a while, but still could not find answers to some questions that I find interesting ( for a reason).

I have a pair of excellent 2-way 4 ohm speakers and i also want to build a pair of balance ZenV4 monoblocks, but still am not sure how good would they be with my speakers:
- will Zens be able to supply enough power, e.g. 70-80 watts
- will they provide good control over the speakers
- how about the dissipation power
- will the MOSFETs from the original design handle all this, or should I use something else, especially for the one in the regulated PSU.

Of course there are many more questions in regard to this issue, which I may eventually ask if this thread develops into something.

Thanks for your input.

Stan

[MikeW]

If you want 70-80 watts you need to build something else. An Aleph 5 running hot , a Aleph 2 or a Aleph X. The Zen as built is only good for about 30 watts. The IRFP are rated to 55 volts.

Well Mike,

Thanks for the reply, but I am talking about a balanced version of ZenV4, that means it looks more or less like a differential pair, and the speaker sits between the + and - outputs.
One would expect more current supplied to the load, therefore more power.

My questions were about the interaction between a 4 ohm speaker and a balanced ZenV4.

Regards

Stan

[MikeW]

Yes, I understand. The balanced version (2 boards) will put 60 watts into 8 ohms. It would be easier and you would have more flexibility if you use the other designs.

[Nelson Pass]

80 watts requires 160 watt peaks, so v^2=W*R
v^2 = 640 and v = 25.3. Each half of the balanced
amp needs to deliver 13 V peak, and so the regulated
supply should be about 30 volts.

160 peak into 4 ohms, I^2 = W/R = 40 so I = 6.3 amps.
This means that the bias on each of the 4 transistors is
3.15 amps and the dissipation on each device is
15 volts * 3.15 amps = 48 watts.

This is at the upper limit of what I would operate these
devices at, but with enough heat sinking, it is do-able.

Thank you all for the answers.

I would like to re-phrase the question a little bit - if I built a balanced version of ZenV4, using the Pass Labs boards and couple of Q-packs, what output power can I expect at 4 ohms, also if I increase the bias to 2.8 amps (per each half and keeping the supply voltage the same), would the FETs be sufficient for the job or shouldI go for somehing bigger.

Stan

[Nelson Pass]

It will clip at 60 watts, 120 peak, and the Mosfets will
take it if you give them adequate sinking.

Thank you for the kind reply, Mr.Pass.

Seems I'll have to build something different, maybe Aleph 2 or Volksamp 60 to achieve the desired output and control at 4 ohms.

Kind Regards

Stan

[Pukki]

I have now planned for some time building the Penultimate Zen amplifier. Not a long ago I got an idea two make two of those and use them as balanced monoblocks. After all I have enough heat sinks for a pair of them. And I also have two 800VA 2*36 transformers. I was planning to use one wingding per one board.

Would 400VA / channel be adequate rating in balanced setup? And what about capasitance. I was planning to use 22000 uF+10000 uF capasitors per channel. And how much bias can I give for the amps using these transformers? Or will I meet the limit of Q1 before the limit of the transformers? I know my heat sinks wont be the limit.

I'd also like to know that how can I build a balanced source. I would have to get balanced signal out of unbalanced. Would Bride of Son of Zen help me out with this?

[Super_BQ]

Pukki,

Balanced dual zen 4 monoblocs? Hrm... Sounds like a GOOD idea!

BQ