L'Amp: A simple SIT Amp

[gadut]

I find that acronman only has 1pcs of KD-33, is it still good to use KE-33 that are available? I'm planning to use it on SIT CCS version that seems to give a flat response http://www.audiohobby.com/pdf/lamp ccs.pdf

 

[DIYspaceW]

I find that acronman only has 1pcs of KD-33, is it still good to use KE-33 that are available? I'm planning to use it on SIT CCS version that seems to give a flat response http://www.audiohobby.com/pdf/lamp ccs.pdf

I think yes. KE-33 and KD-33 should be very similar. Whats important is the
number...I would bother much and buy the KE..

 

[Nelson Bass]

I find that acronman only has 1pcs of KD-33, is it still good to use KE-33 that are available? I'm planning to use it on SIT CCS version that seems to give a flat response http://www.audiohobby.com/pdf/lamp ccs.pdf

Look again, I see 4 available for sale.

 

[DIYspaceW]

Interisting observation, I bought four 2SK82 KD-33 and I measured the Drain to Source resistance on each. Two had around 1 ohm and 2 less, around 0.80 ohm. In the datasheets of Sony V-fet amplifier states a good transistor should have 1-2ohms.
More, when I first powerd up my high voltage amp, I expected to have some bias differences because the SITs have very broad specs, but the opposite is the keys.

 

[gadut]

I just order 2pcs KD-33 from acronman, he just did not update his stock on ebay.

With CCS version which require 35V for +V, i'm planning to use my existing 2x25Vac @300VA that is powering my_reff. when I measure on my_reff, I get 34Vdc. Does 1V difference will impact on overall performance?

What is the minimum watt rating for 1ohm resistor before SK82?

 

[DIYspaceW]

I just order 2pcs KD-33 from acronman, he just did not update his stock on ebay.

With CCS version which require 35V for +V, i'm planning to use my existing 2x25Vac @300VA that is powering my_reff. when I measure on my_reff, I get 34Vdc. Does 1V difference will impact on overall performance?

What is the minimum watt rating for 1ohm resistor before SK82?

I assume 10W would be suffcient...

 

[Nelson Pass]

I bought four 2SK82 KD-33 and I measured the Drain to Source resistance on each. Two had around 1 ohm and 2 less, around 0.80 ohm. In the datasheets of Sony V-fet amplifier states a good transistor should have 1-2ohms.

A lot depends on how you measure the resistance.

My experience with quantities of Acronman's Sony SITs is that they
are all good, but as usual you have to match Vgs, as they are ranked by
ranges, not exact values.

 

[OllBoll]

Got the 193V inductors today and while they are smaller than I feared they are still quite big...

And I started to think about the layout with all the caps: the first plan was CRCRCL -> amp, but when simulating in PSUD2 I get better performance if I do a CRCLC -> amp instead. If I'm not mistaken there isn't any issues with doing this but since I haven't seen anyone do it I might as well check with you =)

 

[gadut]

What is actually the function of 2 bulbs on the circuit? Only to reduce voltage? I'm thinking of using lower voltage from transformer output and play with several resistors to get desired voltage as 2 bulbs version

 

[juanitox]

Got the 193V inductors today and while they are smaller than I feared they are still quite big...

And I started to think about the layout with all the caps: the first plan was CRCRCL -> amp, but when simulating in PSUD2 I get better performance if I do a CRCLC -> amp instead. If I'm not mistaken there isn't any issues with doing this but since I haven't seen anyone do it I might as well check with you =)

Why just do it simple with a CLC or CRC as original ? The 193V act as a filter too'...

 

[OllBoll]

Why just do it simple with a CLC or CRC as original ? The 193V act as a filter too'...

I already have the caps and mounted in the box so I might as well use them =)

 

[DIYspaceW]

Has someone tried to bias the SIT whit lifepo4 batteries or also 9V rechargeable??
I was experimenting whit source degeneration and must say that it sounds
a little strange to me, not much of life...)
So I have only two choices to bypass whit cap or to go for a fixed bias...

 

[Michael Rothacher]

Battery bias worked fine. Of course, the operating point changes as the battery drains and if you let it drain too much your SIT goes poof, so you have to be mindful of that.

 

[DIYspaceW]

It depends how you set the voltage divider for the battery. I will give it a try
whit two 9V alcaline as I have -12V bias point.

 

[Michael Rothacher]

What depends on "how you set the voltage divider for the battery"?

 

[DIYspaceW]

drain current of the battery will be different if you put higer resistance to voltage diveder, thats why I mean,
of course in limits, so I can extend the battery life a little in case of SIT.

 

[Michael Rothacher]

Battery bias worked fine. Of course, the operating point changes as the battery drains and if you let it drain too much your SIT goes poof, so you have to be mindful of that.

Perhaps I point out the obvious too often, but it saves me from nasty emails

 

[vdi_nenna]

Mike,

What happened to the SIT preamp?

Thanks,

Vince

 

[Michael Rothacher]

Good question. The "LuminAria" article has been finished for some time. I sent it to a popular print publisher and I haven't heard anything yet. I'll let you know when I hear something.

I also have an article in the upcoming volume of Linear Audio. It's more of a technical piece.

 

[vdi_nenna]

Can I send you $10 via paypal so I don't have to wait?
Seriously.