Build This MoFo!

[Michael Rothacher]

The right rug is key.

 

[BeardyWan]

I'm waiting for tweets of "Fake News!"

 

[drpro]

I am placing my order from Mouser for parts and I cannot find "the rug" in the parts list.
Help please

 

[vitalstates]

I found 2 of these smps on the shelf, unopened from an abandoned GM70 project from way back.

I thought I’d see what the circuit sounds like, powered by these power supplies. Circuit shows 2sk1058 but the ecx latfet is supposed to be a drop in replacement and I couldn’t find a spice model for the ecx. It sims at about 3.5 watts with a bias at 1.6 amps and it’s very slightly down at 30hz. It looks to dissipate about 36 watts. I’m keen to compare it with the ancient 3.5 watts of 2A3 in the project studio system.

I'm currently creeping up on decoupling the ac injected into the power line via both bias lines. Any comments would be gratefully received.

I had to put the VAS in as I only have 2 volt line level sources.

 

[indra1]

... I couldn’t find a spice model for the ecx. ...

Available in the Better power MOSFET models in LTSpice thread.

 

[vitalstates]

thanks Indra, will swap them over...

but I am a bit confused(not difficult to achieve). The models you linked to all show VDMOS which to me implies that they're all vertical fets. The ecx10n20 is a lateral beasty......Am I being particularly dense today?

 

[drpro]

CRC value suggestions for use with the SMPS supplies? New for me, have only been using linear supplies. Going with the 24v from All Electronics.
Thanks

 

[indra1]

... The models you linked to all show VDMOS which to me implies ...

It is just the terminology to differentiate with previous model card. The VDMOS takes into account cgd non linearity and ksubthres (subthreshold drain current). Don't worry, the model does work well.

 

[meanman1964]

Can I use a 22K trimmer instead of the 20K ?

 

[Dennis Hui]

I see no problem.

 

[Zen Mod]

yup

 

[316a]

I thought I’d see what the circuit sounds like, powered by these power supplies. Circuit shows 2sk1058 but the ecx latfet is supposed to be a drop in replacement and I couldn’t find a spice model for the ecx. It sims at about 3.5 watts with a bias at 1.6 amps and it’s very slightly down at 30hz. It looks to dissipate about 36 watts. I’m keen to compare it with the ancient 3.5 watts of 2A3 in the project studio system.

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

 

[vdi_nenna]

CRC value suggestions for use with the SMPS supplies? New for me, have only been using linear supplies. Going with the 24v from All Electronics.
Thanks

I don't think CRC are recommended with SMPS, but maybe someone else will chime in.

 

[flocchini]

The MoFo with Jensen autoformer

I need to get a bit more gain with my MoFo

I was wondering if I could replace the input cap with the autoformer pictured in the attachment. I've used it with the F4 - hence the designations shown

Thanks

Bob

 

[PSz.]

replace the input cap with the autoformer pictured

Nope. You still need the cap to block the bias dc.

 

[BeardyWan]

If you leave BRN and GRY disconnected then you can feed the bias voltage in on GRY:
Connect GRY to cap to signal reference /common and in parallel connect to voltage divider between rails to feed DC bias voltage in.

 

[Michael Rothacher]

MoGain MoFo

Or maybe in the style of SIT-3

 

[PSz.]

Or maybe in the style of SIT-3

I like this one. Might be time to go sit on the rug and think more about it.

 

[flocchini]

Thanks guys

 

[flocchini]

OK lets see if my brain is working -

Eliminate R5

In place of R2 place the autoformer with Brn/Grey to R3, Orange to FET and Red to a ground ( through a cap. Cap value = ???

Thanks

Bob