L'Amp: A simple SIT Amp

[DIYspaceW]

No, but I had also autoformers in mind...
This is a good solution for higher voltage curves of 2sk82 but
you wont get rid of the big elec. cap.

Originally Posted by flg

Have you talked with these guy's???
Autoformers offered by ZeroImpedance- Improve your speaker sound quality with the use of an autoformer.

[generg]

I played again with the SK82 and a CCS version with a R100. The rival was a R085 instead of the SIT.

The gain with the R085 was ugly high, about 25-30x and you could already hear the hiss from the semi with my 86db Lowther.
Sound was heavy and good, but not spectacular.

The sound with SIT was much more detailed, but very thin.

ZM advised me to seek for the reason not in the CCS, but in the lower part.

First I thought that the different transconductance makes the difference.

Around 5-6 Siemens against 0.5 Siemens. Or was it the big amplification difference hat fooled me....
Later I read Mikes article again, and stopped at the 'load line' term.
Indeed I had a combination of voltage and current for the Sit that was not on the loaddline Mike showed.

I chosed the 19V/1.6A point and I have the strong impression that the sound now lost the overly bright character.

Am I fooled by my exspectations? Does anybody have similar experiences?

Or is it simply the different combination of K2 and k3 that pleases me.
What is the advantage or disadvantage to be on the loadline with the SIT?

Is it possible that the importance of loadline is less important with the R085?

Any answers welcome!

[Telstar]

I believe that the K82s need to be matched a bit, following the loadline in Mike's article.
I dont have a tracer for high voltage/current, but I can tell for sure that there is a lot of variance among the sony SITs. I have 4 units, two are decently close, but the other two are way off (at the extremes).

[Zen Mod]

as i said - and 'twas not invented by mighty moi - THD spectra is explanation for everything

The Class-A Amplifier Site - Jean Hiraga Index , just few general remarks , but these will maybe lead you further

there are more papers on French , but I will must wait to meet my fave Froggy Yoda for clarification ....

[Michael Rothacher]

The R085 is more pentodey than a 2SK82 so there's less opportunity for working the loadline in OTL territory. Interestingly, the R085 (I posted some curves somewhere recently) is probably more well suited to an SET coupled design as it's more triodey at low-current high voltage. You probably couldn't go real high on the primary impedance, but a 64-150 Ohm transformer is probably workable, e.g. NP's Arch Nemesis.

You might also want to try a bit of degeneration with the R085, if the f-word doesn't bother you.

For the second part of your question: with a SIT, working the loadline to get the harmonic flavor you like best is where all the fun is. In my experience when the second and third harmonics are about the same magnitude things start to sound more threadbare.

[Salas]

Originally Posted by Michael Rothacher

The R085 is more pentodey than a 2SK82 so there's less opportunity for working the loadline in OTL territory. Interestingly, the R085 (I posted some curves somewhere recently)

Here your traces again, annotated.

[Zen Mod]

ACA upper part is interesting , as load

ya didn't hear that from moi


btw. Mr. MR ....... where are you lately ....... Buzz iz having all the buzz for himself , without us

[Telstar]

Originally Posted by Michael Rothacher

In my experience when the second and third harmonics are about the same magnitude things start to sound more threadbare.

threadbare - what does this word mean?
I tend to prefer the 2nd bout 33% higher but you surely got more experience than I.

[buzzforb]

Originally Posted by Zen Mod

ACA upper part is interesting , as load

ya didn't hear that from moi


btw. Mr. MR ....... where are you lately ....... Buzz iz having all the buzz for himself , without us

ACA is perfect, in fact. No degeneration, more for feedback if you want it. Its in my R085 thread ramblings. Nelson answered in fairly direct way, as matter of fact.

[Zen Mod]

you're like squirrel , jumping all the time

I can't follow ya ....... so - from now - you must put a link to everything you mention

wakoosquirrelyank