50w Single-Ended BAF2015 Schade Enabled

[Soundhappy]

Any issue with installing the 4N37 from the underside of the PCB in a point to point setup?
When upside-down, the 4N37 pins match the schematic perfectly. I don't think it would cause a dissipation issue, but thought I'd ask.

thanks,

Vince

Me too I think installing the 4N37 in underside position is not an issue

 

[vdi_nenna]

Thank you!

 

[Soundhappy]

Great Vince Enjoy this build!
What Your transformer choice model at the audio input ?

 

[vdi_nenna]

The Jensen, because I've had a pair for a long time.

 

[Soundhappy]

Big YES for the Jensen's quality
My as well is point to point soldering made amp.
Next step is to try all technology
: carbon, mox, metal film, wire wound, bulk foil, etc.
rolling of 220R 3 Watt's feedback resistors, 22R at the drain and
if I get another input transformer just for the pleasure to hear the difference in acoustic instruments tone fidelity.
BTW IXYS price go up

 

[vdi_nenna]

Must be worth the effort.

 

[Soundhappy]

I agree and it's easy amp " sound tuning " for the particular speakers pair.
Please Vince post us Your Schade amp construction report Have fun

 

[vdi_nenna]

If I were to lower the voltage of the circuit from 60v to 40v, would the drain of the mosfet be at half the circuit voltage, e.i., 18v-20v?
Is this similar to the ACA bias adjustment? Would I then monitor the drain voltage while adjusting the bias at the gate, arriving at around ~20v?

Thanks,

Vince

 

[Zen Mod]

yup

goal is to have symmetrical behavior of amp's output , in voltage domain .... thus resulting in highest possible power (from voltage window) ..... finally resulting in so-so symmetrical clipping

 

[vdi_nenna]

Great! Now I feel better about starting the project.

 

[vdi_nenna]

220R 3 Watt's feedback resistors, 22R at the drain

Happy, is the 22R, near the 220 3W, a 1/4w resistor?

I'm starting to piece parts together tonight. Finding I'm missing a few parts.
More orders.

thanks,

Vince

 

[Soundhappy]

Hi Vdi_nenna

22R is 1/4 watt 220R / 3 watt's minimum little bigger is always ok

 

[vdi_nenna]

As always, Thank you very much!

 

[Soundhappy]

Missing parts is for Papa TL431 bias curcuit ?
Work like a charm

 

[vdi_nenna]

Are you using this circuit for the bias section?

 

[Soundhappy]

Big YES is perfect for the IXYS bias inside the Schade 50W
Multiturns trimmer for voltage precision.
Zen Mod version if made with other resistors values.
Schematic courtesy of Mighty Pumpkin

 

[Soundhappy]

Are you using this circuit for the bias section?

How much of the bias for Your mosfet ?

 

[vdi_nenna]

Good question. Will be using a IRFP250. I believe it's based on how much voltage will appear at mosfet drain, which is around 18-20v, depending on symmetrical clipping. Not sure what the figure will be. Will have to monitor it while adjusting.

I have a prebuilt LM317 circuit to speed up the build process. The transformer has extra 12v and 18v secondaries, so voltage is not a problem.

 

[Soundhappy]

Cool Vdi_nenna build with H2 , H3 switch on the CCS ?
Between D and C 0.1R resistors connection points.

Me ask swap IXYS to SIT: 2SK180, THF-51 or 2SK182ES.
Mr Pass use 2SK77B any datasheet available to compare with similar Tokin's ?
FAB like experiments but not rare triode sand smoke

 

[vdi_nenna]

Cool Vdi_nenna build with H2 , H3 switch on the CCS ?
Between D and C 0.1R resistors connection points.

I'm not that adventurous. I'm going to keep it simple, keep it as-is.