L'Amp: A simple SIT Amp

[Telstar]

Originally Posted by OlavHaal

And I have moved to building Dac`s for a while(even if I have a couple spare 2SK82 waiting for LumiaAria - if that is the chosen part!!!)
The sound is so full-bodied and elegant - as is - with the Alp12P!!

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.

[OlavHaal]

Originally Posted by 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!

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

[protos]

I doubt 2sk82 is suitable for preamp duties. To start it's gain is not high enough not to mention the capacitance problem.

[Antoinel]

Originally Posted by OlavHaal

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

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

[Zen Mod]

MR , do you have (by any chance ) LTSpice model for 2SK82 ?

where you been lately , cookin' something ?

[dantwomey]

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.

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

Regards,
Dan

[Rush]

Originally Posted by dantwomey

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.

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

[dantwomey]

Originally Posted by Rush

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

Rush

MR would say Ohm's Law. R=E/I

[dantwomey]

Originally Posted by dantwomey

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.

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

[Michael Rothacher]

Originally Posted by Zen Mod

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.