Live Lab Hangout #1.1 Posted

[generg]

The distortion values look very much like the values Nelson shows in the SIT-1 user manual.
Only difference his current is around 1.5A.

 

[jama]

Ah, sorry, I have not look this manual. I will do it. Well, with this tool (it is old but this equipment works very well) I can try a lot of things measuring what happen. The first, as Michael said me, is try with more PS voltage, around 84V and other quiescent point, around 2A (I have get two 400VA 60V trafos and 8 22000uF/100V). Second, use 2SK180 instead THF51. But always comparing with a good system. Fun has just started...

 

[generg]

Nelson told me in a mail that he uses around 40- 45Ohm as drain resistor iin order to get a higher gain......
Yes and with 84V and 2A you will get for sure very good results.

 

[jama]

With 10Ohm I have gain of 5 (14dB). I will try soon. Sure. And I will write here my findings. Thank you for sharing. Regards all

 

[generg]

Thank you for going a way I want to go in late summer now!



So I will have less problems.

 

[jama]

Another way will be evolve circuit...

 

[generg]

very nice….!

IRFs for voltage stabilization and a buffer with J-Fets?

 

[jama]

No. It is experimental. Two ccs and driver for gate of k180. Remix of evolve amps. Sure that two ccs in paralel is wrong, but i have get 5w rms with good result. Ah, they are not jfet, are bipolar. The same evolve used.

 

[dady]

This is my Spaniard friend. Man of facts.

 

[dady]

 

[jama]

The second channel is better than first one. And with this channel i have reach 14W rms with 7% of thd

 

[jama]

Before doing evolve circuit, I simulated it with Pspice. I could not use 2sk180 model (I tried it but I could not did it without errors). Then I used 2sk82 model from Michael, just to see if works. The first with schematic and input and output signals.

 

[jama]

Now voltage, current and power screens

 

[cwtim01]

Now voltage, current and power screens

How does the SIT sound in this more conventional circuit with GNFB ?

 

[cwtim01]

... 2SK180 is approaching unobtainium even in China ...

It seems situation has changed lately. Out of nowhere, someone setup a brand new TB Store (sort of e-Bay shop but in China), and has hundreds of NOS 2SK180 from Japan available, as well as NOS 2SK182ES and THS-51.

I'm hesitant to order anything from him though, it's always a risk to buy things from a new online shop. Also, the serial number (1Y....) of the 2SK180s are remarkably close to those from eyelabo (1Z....) before and they might be from the same source.

 

[Soundhappy]

@ Cwtim01

Seller from Tokyo don't have THS-51 in his store in the past.
If money back possible why not few sample ?
But yes is " Y grade " the same i have
Btw 40 V smps psu for Locky_Z curve tracer what link to buy good one ?
Tests of all my Tokins are urgency now
Little set 2A3 triode 3 watt's amp run last days for better know how different
music emotions feel if compare to future sit's amp.
Work in progress

@ Jama
AMAZING WORK BRAVO
Best regards

 

[bravi]

Update on SIT sourcing

Purchased a box of new 2SK180 from online site in Japan- not from Eyelabo who had also listed at the same time.

Will get them in a few weeks time. Hoping that they will be good( most of them at least)- a big punt on my side.

 

[generg]

@jama:
the 2SK180 model might be arranged for LTSpice and the change for the PSpice is a bit complicated.

The circuit you show has some similarity with the First Watt J2 and this amp sounds great!

 

[cwtim01]

...Btw 40 V smps psu for Locky_Z curve tracer what link to buy good one ?...

I use something like the attached one, when I examined it with a scope, it has some tens of mV of typical switching noise, but it's good enough for the locky tracer.

If you can't find one in your local electronic store or e-Bay, I have a spare one where I can sell you at EUR10 (plus shipping). Issue is that shipping cost to Europe is probably 3 times the cost of the power supply. PM me if you're interested.

 

[cwtim01]

... If money back possible why not few sample ? ...

Can't resist the temptation so ordered a pair