Φοβοῦ τοὺς Δαναοὺς καὶ δῶρα φέροντας
Well, Serbs in this case though usually friends of the Greeks. I'll let you know what the guy says about his parts.....
I have another question as I contemplate a build. I already have a pair of heatsinks 300x150x40mm, C/W 0.36. If I use these do I decrease the DC voltage from the PSU? And if so by how much?
Thanks for help here.
Thanks for help here.
If your heatsink doesn't quite have enough capacity, decrease the current rather than the voltage.
When you bias the amplifier, monitor the heat sink temperature and set the bias current for 55 degrees C maximum at the heat sink.
When you bias the amplifier, monitor the heat sink temperature and set the bias current for 55 degrees C maximum at the heat sink.
You should be fine.
I have a 300-150-40 0.31C/W heatsink and it’s just fine at 250mV bias (and +-24V of course)
Edit: although It don’t remember the exact temperature, I remember I could’ve run mine even with 275mV but as I am a fearful builder went down that bit…
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I think the 300-150-40 is 0.36 and the 300-165-40 is 0.31, but pretty close.
I just had a thought about the width of the PCB in the DIY Audio store - fortunately it says it's 250 x 50mm. It would have to fit the 300mm heatsink, but that looks OK.
https://diyaudiostore.com/products/f-4
Just thinking...... I leave my system on 24/7 because I play music at night to send me off to sleep. So would 300/150/40mm be OK at a lower bias? Like shoot for 200mV and measure the temperature? I'm even wondering about a 15+15V transformer for 24/7......
Well, my 2a3 amp is on 24/7. No problems there. I've never owned a Class D amp.
But it is what it is, system stays on 24.7. I need to be able to get back to sleep in the night and lying there in silence thinking about stuff for hours doesn't work. Music stops stray thoughts and works quite quickly.
If it is ok running several hours, then it doesn't mind 24/7. I'd try it for sure.
It will just age a little faster.
I don't know whether it actually can run at a lower voltage. Lower bias is no problem, except that distortion get a little higher.
And I think Adason's right BTW. Maybe a signal sensor (sending the amp to standby when no signal's going through for some time... ?
It will just age a little faster.
I don't know whether it actually can run at a lower voltage. Lower bias is no problem, except that distortion get a little higher.
And I think Adason's right BTW. Maybe a signal sensor (sending the amp to standby when no signal's going through for some time... ?
"Age" in what way typically? Which parts especially?
I have no idea how a signal sensor works but sounds interesting.
Every plate amp i have is equipped with auto on/off function. Even AudioSource amp i once had, has it.
Or use timer...
Or use timer...
If you can get by with less power than that offered by the F4, you should consider the Mofo:
Mofo Amplifier
The low power version is 1.7A at 19V, good for about 10W.
Or if you some VFETs, do a single ended choke loaded VFET follower. The dissipation would be roughly the same.
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The MoFo is a really good idea, and I have some chokes 280mH and 2.7A which should be perfect for it. I'd prefer a transformer output to a capacitor - any suitable production ones?
Anyone built the F4 and the MoFo and can describe the differences sound-wise?
Anyone built the F4 and the MoFo and can describe the differences sound-wise?
Transformer output from a mosfet follower ? There are no suitable ones made, because it’s not really possible…
As for mofo vs F4, yes, I’ve built both. The F4 has no sonic signature if its own, it always sounds like the upstream preamp. MoFo is also neutral ish but has a very pleasant sound.
As for mofo vs F4, yes, I’ve built both. The F4 has no sonic signature if its own, it always sounds like the upstream preamp. MoFo is also neutral ish but has a very pleasant sound.
In his Mofo article, Michael Rothacher said that you could substitute other Mosfets such as the IRFP240, but that "the IRFP250 is just about optimal, and they're dirt cheap".
Since you enjoy single ended triodes, you may prefer the triode character of the Mofo over the F4.
The Mofo does not have many parts so it is easy to build with point to point wiring, especially if you have a spare 19V computer power supply handy.
Since you enjoy single ended triodes, you may prefer the triode character of the Mofo over the F4.
The Mofo does not have many parts so it is easy to build with point to point wiring, especially if you have a spare 19V computer power supply handy.
Is this an accurate plan of the dimensions of the PCB? I'm planning the heatsinks. The plan indicates 40mm between the centres of the Mosfets - is that accurate?
