Build This MoFo!

[marconi118]

I use the BUZ900P as a SF output stage , this is similar to the 2SK1058 . Both devices have around the same transconductance which is a lot lower than IRF250 . You will get much better performance with a choke load of at least 100mH . Display Electronics used to have 280mH 3A chokes a few years ago with nice thin laminations . A bit lossy with 4 ohm DCR but nonetheless worth try if you need something off the shelf

cheers

316a

Any link to this choke?

 

[316a]

Any link to this choke?

Looks like Display Electronics have been bought out . electroprops.co.uk is the website but I can't locate any chokes on there

If there is sufficient interest , I'll cheerfully arrange a UK group buy of >100mH chokes from my winder if there is an agreed spec . Will probably work out cheaper than the Hammonds suggested

cheers

316a

 

[meanman1964]

I'm planning to test my MoFo with this PSU
It has after the retifier bridge 2x 22000µF caps
PSU is already tested and adjust with an output of 24 Vdc under load

 

[vitalstates]

Looks like Display Electronics have been bought out . electroprops.co.uk is the website but I can't locate any chokes on there

If there is sufficient interest , I'll cheerfully arrange a UK group buy of >100mH chokes from my winder if there is an agreed spec . Will probably work out cheaper than the Hammonds suggested

cheers

316a

All I could find about display electronics was the info from companies house about the company being dissolved. The company that took their stock seem to be a hire company for film props, not a manufacturer by the looks of it.

I'd be interested if you're going to wind some though. I sold my winding engine a couple of years ago and this is the second or third time I've regretted it.

 

[xrk971]

So Vunce has this new Preamp that’s driving his MoFo.

 

[Michael Rothacher]

Very spiffy!

 

[Michael Rothacher]

Or maybe in the style of SIT-3

I think the circuit from Post #637 is going to be noisy if you try to use that with a laptop switcher. It'll be fine with a nice quiet supply of the linear variety though.

I have a few thoughts. But I need to meditate on it...and I see The Blade Runner 2049 4K has just arrived in the mail.

 

[flocchini]

Oh Blade Runner - original was one of the best - hopefully this is the same ballpark

 

[xrk971]

I think the circuit from Post #637 is going to be noisy if you try to use that with a laptop switcher. It'll be fine with a nice quiet supply of the linear variety though.

I have a few thoughts. But I need to meditate on it...and I see The Blade Runner 2049 4K has just arrived in the mail.

Isn’t this like an M2Fo? Although I feel an extra 3x gain on low noise low distortion preamp is preferable to a signal trafo that pickups hum and generates its own 3rd order distortion. I have used M2 with dual 24v smps and it was quieter than linear trafo.

Strange Forest of Noise with Linear PSU

 

[Michael Rothacher]

Using the circuit I posted, inject 100mV of laptop switcher ripple at V+, about half of it will show up at the junction of the two JFET sources, that gets multiplied by three in the autoformer, which goes to the gate of M1.

No?

 

[Zen Mod]

use Papa's tricks from DEFiSIT

 

[vdi_nenna]

Hey quick question. Looking at the F4 manual, I see the F4 can be driven with a flea-watt power amp. Is there a power limit to the amp in front of a follower such as the F4 or MoFo? I don't have a high gain preamp yet, but do have a class-D amp with volume control. It's a Dayton Audio 40w amp. If it's not safe, then I'll skip it and wait.

thanks,

Vince

 

[Zen Mod]

skip and wait

first and most important , that thingie certainly isn't worth to be connected to F4

if nothing else , build OP based headphone (pre)amp and connect to F4

 

[vdi_nenna]

that thingie certainly isn't worth to be connected to F4

You're right.

 

[Zen Mod]

take FE of M2

'nuff gain ..... and - what's better than one Iron ........ only two of them

 

[indra1]

Especially with more nickel in them.

 

[Zen Mod]

which is more important ?

more nickel ........... or less dime ?

 

[BeardyWan]

The SIT-3 circuit as originally posted has the positive rail nailed to ground. Nelson notes that the noise rejection of the Vfets is not great and this is one way of ensuring that the supply on the drain is quiet. Or at least I think that's the deal.

 

[flocchini]

take FE of M2

'nuff gain ..... and - what's better than one Iron ........ only two of them

great idea - buffer with gain

 

[Zen Mod]

The SIT-3 circuit as originally posted has the positive rail nailed to ground. Nelson notes that the noise rejection of the Vfets is not great and this is one way of ensuring that the supply on the drain is quiet. Or at least I think that's the deal.

Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans

point is having clean rail (GND ) at VFet drain , and wiggly rail at VFets's source

everything else referenced and de-coupled to clean rail