L'Amp: A simple SIT Amp

Hi Telstar

I missed this... you mean that you will be using a couple of K82 for the I/V stage of your DAC?
If i misunderstood, apologies.


Yes - some misunderstandig - or I made a wrong pronounsement! :usd:

The spare SK82 is meant for the preAmp LuminAria that Michael is preparing with a SIT-part. I don`t know if it is the Sony that is the chosen SIT for that project. I had 2 pcs SK82 if my 1.st pair went up in smoke - and maybe they can be used in a pre-amp later(if I ever get tired of my beautiful PassiveB1).
And my DirectDac(HifiMediy) has 2 Sowtech on the output - so fairly full-bodied sound!:)

Best

Olav
 
Yes - some misunderstandig - or I made a wrong pronounsement! :usd:

The spare SK82 is meant for the preAmp LuminAria that Michael is preparing with a SIT-part. I don`t know if it is the Sony that is the chosen SIT for that project. I had 2 pcs SK82 if my 1.st pair went up in smoke - and maybe they can be used in a pre-amp later(if I ever get tired of my beautiful PassiveB1).
And my DirectDac(HifiMediy) has 2 Sowtech on the output - so fairly full-bodied sound!:)

Best

Olav
OlavHaal: According to Zen Mod, it is quite possible to keep the bias on these V-Fets all the time; from the time the amp is plugged in the power outlet. This will prevent inadvertent burnout.

Best regards
 
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Joined 2002
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used two 300 Watt light bulbs whose parallel resistance is in the 11-13 Ohm range. Make sure the bulbs you buy are 300W @120V. The first bulbs I tried were marked 300W@130V, so they’re really 266W bulbs. You’re looking for 11-13 Ohms, so if you have a cache of the 130v bulbs, which are about 39 ohms each, you should be able to use three of them in parallel. Of course a big power resistor works fine too.

The above quote from Michael's first SIT article got me thinking and I took my bulb's out for a measurement. My bulbs are 300 WATT Philips PS25's Philips | 300W PS25 Clear | Home Depot Canadaand with a meter they all measured 4 ohms. With two in parallel for each channel that makes 2 ohms and my amp seems to be running fine. Very puzzled. :eek:

As a comparison I took some 60W incandescents out of the cupboard and they all measured 17 ohms. Hmmmmmmmmm.......

Regards,
Dan
 
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The above quote from Michael's first SIT article got me thinking and I took my bulb's out for a measurement. My bulbs are 300 WATT Philips PS25's Philips | 300W PS25 Clear | Home Depot Canadaand with a meter they all measured 4 ohms. With two in parallel for each channel that makes 2 ohms and my amp seems to be running fine. Very puzzled. :eek:

As a comparison I took some 60W incandescents out of the cupboard and they all measured 17 ohms. Hmmmmmmmmm.......

Regards,
Dan

When the filament heats up the resistance goes up. Check the voltage drop and current and do the math.

Rush
 
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Joined 2002
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The above quote from Michael's first SIT article got me thinking and I took my bulb's out for a measurement. My bulbs are 300 WATT Philips PS25's Philips | 300W PS25 Clear | Home Depot Canadaand with a meter they all measured 4 ohms. With two in parallel for each channel that makes 2 ohms and my amp seems to be running fine. Very puzzled. :eek:

As a comparison I took some 60W incandescents out of the cupboard and they all measured 17 ohms. Hmmmmmmmmm.......

Regards,
Dan

My SIT is up and running quite well but I've been checking various things in search of an answer to one issue I have. On one channel the Id had a range of almost zero up to 2.4 amps. On the second channel the Id would go down to a minimum of .6 amps up to a maximum of 2.6 amps. I solved the problem today by replacing the transistor on channel 2. Now both channels have the same range of Id.

Regards,
Dan :)
 
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Joined 2001
Paid Member
MR , do you have (by any chance ) LTSpice model for 2SK82 ?

where you been lately , cookin' something ?

Hi, ZM. If ballpark is okay, I have approximated SITs with Koren Triodes.

Attention all eggheads: I wouldn't land a probe on Mars with these or get too excited about distortion figures and such. Stay mellow and have fun.
 

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Member
Joined 2002
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Since Antek is temporarily out of business because of a fire I've looked elsewhere for a toroid for the 193V SIT and this is what I've found. SumR - Richard Sumner Technology has quoted me the following.

Single Primary 117V 60Hz
Four Secondaries
Two @ 15VAC 2A
Two @ 18VAC 8A
Total: 350VA.

With core band and mounting hardware:
Price Cdn $ 105/e.

Double what some Anteks cost but exactly you need for Micheal's circuit.

Regards,
Dan
 
Official Court Jester
Joined 2003
Paid Member
Hi, ZM. If ballpark is okay, I have approximated SITs with Koren Triodes.

Attention all eggheads: I wouldn't land a probe on Mars with these or get too excited about distortion figures and such. Stay mellow and have fun.

much obliged Mr. MR ;)

I'm primary interested in that because I want to alter some values in one sch, for Generg's 2SK iteration

:cheers: