Article - Sony VFETs part 1

[george_ct]

I just finished reading the article. Very delightful.

 

[PKI]

I assume that 25V power transform can be used without any modification of regulators, right?

 

[Zen Mod]

yup

 

[PKI]

I am actually surprised with Nelson suggesting 300VA per channel. 1.5A per device are usual values for many FW amps, and Papa is using 300VA per amp in there 🙂

 

[Zen Mod]

there is slight difference between 2x18Vac/300VA and 2x24Vac/300VA ......... and also square law dynamic potential ........ making somewhat greater demands to eeeny weeeny PSU

 

[PKI]

Thanks, I see 🙂 another thing is: from BAF talk I remember the presenter 🙂 mention that due to SITs impedance you can't drive anything but 8ohm (maybe even in OB) with this amp, however in the article it doesn't spiny that bad. Can you use it for a speaker with a crossover? 🙂

 

[Zen Mod]

there are xovers ........ and there are xovers

for instance - on one of my spks , entire xover is just one cap

in other , there is mucho parts

try and hear 😉

 

[PKI]

I am trying to find out if there is any point of making amp or should I order Sonido drivers first 🙂 I have only speakers with mucho parts 🙂)

 

[Zen Mod]

friendly and highish impedance module is what you need , having amp with highish output impedance

as I recall , Papa covered some interesting extremes in article

 

[Nelson Pass]

Thanks, I see 🙂 another thing is: from BAF talk I remember the presenter 🙂 mention that due to SITs impedance you can't drive anything but 8ohm (maybe even in OB) with this amp, however in the article it doesn't spiny that bad. Can you use it for a speaker with a crossover? 🙂

I found them well behaved into 4 ohms. I took square law data into 4.

😎

 

[PKI]

Thank you ZM and Nelson, that's promising 🙂!

 

[Bones13]

Looking forward to this amp. I got VFETs and transformers early, shortly after BAF. I'm working on a DAC now, and watching this story unfold.

I am loving the Aleph J into my Zu Audio speakers (crossover is one cap, as mentioned by ZM)

Thank you some more Nelson Pass!

 

[Zen Mod]

cap and resistor

 

[Bones13]

Could be I guess. I did the recent upgrade to my Essence speakers, and only a capacitor, which replaced a small bundle of smaller caps was changed, along with unhooking one lead. Perhaps there was a resistor deeper in there on the tweeter itself.

 

[Nelson Pass]

There's resistance everywhere...

😎

 

[Gyuri]

Notre peuple vaincra (Les sous doués) - YouTube

 

[Tea-Bag]

Anyone know how much the Irf's would dissipate under 1.5a load?
Is mounting to the chassis floor seem sufficient? Or should it be placed on primary heatsink?

 

[R-K Rønningstad]

Depends on your unregulated voltage. It could easily become 20 W. P = (Vunreg - 24V)*Iload.

 

[R-K Rønningstad]

PS. Provided Iload = 1.5 A cont.

 

[Tea-Bag]

So guess about 12W assuming unreg or 32v. So 24W on the bottom of chassis is not trivial. Doing two supplies on chassis floor would be problematic!