no prob with that , is one of the sweeter amp I had the pleasure to build .
BTW , very good also the Sony sit , maybe I would prefer a little more gain , but it's ok .
I will look forward to read from MR. Pass how to address the capacitive issue ( beside the wonderful B1 stage and the cascode operation) , if I am not wrong there will be some writing about
To be clear, I don't recommend anything other than KD-33 for Figure 11. KD-33 just happens to bias-up right where we we need it to with a small enough source resistor.
KE-33 and others will work just fine so long as you plan to use the separate bias supply (Figure 10, or see my first post in this thread for a compete schematic), which has the added benefit of no degeneration and more gain. Other grades will bias-up at different voltages than those listed in my tables. The operating point (Id and Vds) will be the same.
For example, the KE-33 I tried biased-up at around -8V.
KE-33 and others will work just fine so long as you plan to use the separate bias supply (Figure 10, or see my first post in this thread for a compete schematic), which has the added benefit of no degeneration and more gain. Other grades will bias-up at different voltages than those listed in my tables. The operating point (Id and Vds) will be the same.
For example, the KE-33 I tried biased-up at around -8V.
I can confirm 6db gain.....
So Nelsons SITs seem to have another curves with more gain...
If you mean the PASS-SIT-1, yes it has much higher transconductance.
Does this mean you have a working amp?
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Capacitance? The way to address that is to build or use a preamp with a 600 Ohm or lower output impedance.
BTW, the response numbers in the article are with a 600 Ohm source. With a 50 Ohm source, the SIT amp is flat beyond the 100kHz capability of my analyzer. And, I had no trouble using 47K input resistors with my samples.
BTW, the response numbers in the article are with a 600 Ohm source. With a 50 Ohm source, the SIT amp is flat beyond the 100kHz capability of my analyzer. And, I had no trouble using 47K input resistors with my samples.
If you mean the PASS-SIT-1, yes it has much higher transconductance.
Does this mean you have a working amp?
Yes but with an CCS similar to F2 and I operate only with +24V minus 4V I loose with a big 2 ohm resistor to get -4V for the biasing. So I have only about 10V source drain voltage and at the moment and 2A current.
And being only being a beginner I am still searching to get closer to your values.
I suppose I will take for the bias a separate PSU to get the 4V back and continue playing, it is great fun....
Tomorrow I will change the KE-33 against the KD-33....
Infact both IXYS and Sony versions works good with the B1 ( also modified ) .
I must say that the Sony SIT has a very good timbre balance overall the sounds and instruments , and the basses in particular are wonderfully articulated with a great sense of space !
I have built several CCS versions now. Dialing in the sweet-spot and gain proves to be a little tricky, like squeezing toothpaste back into the tube.
Oddly enough, I keep going back to the non-ccs versions, and I'm forming the opinion that these devices are at their best in minimalist circuits.
Oddly enough, I keep going back to the non-ccs versions, and I'm forming the opinion that these devices are at their best in minimalist circuits.
Thanks, Stefano
I knew I could count on you to be one of the first.
May I ask what speakers you use?
YesssThanks, Stefano
I knew I could count on you to be one of the first.
May I ask what speakers you use?
I still use the Fostex Fe 206 E equalized for current source amps ( then with a parallel network of C and R ) into the Quarter Wave MLTL Box .
Do I understand you right Mike, the dialing in of the the sweet spot is more tricky with the CCS and less tricky with the bulbs?
Or was your reason to return more the better sound with the bulbs.....?
SITs really are different, and don't necessarily plug right into our old MOSFET circuits. It's a slightly different paradigm.
For example, MOSFETs perform reasonably well at a variety of operating points, which is why we can often just plug them in and crank up the voltage and current until we're happy.
The SITs have a narrower, but clearly more effective sweet spot. When I first started experimenting with them, their workings were often counterintuitive based on my MOSFET upbringing.
For example, MOSFETs perform reasonably well at a variety of operating points, which is why we can often just plug them in and crank up the voltage and current until we're happy.
The SITs have a narrower, but clearly more effective sweet spot. When I first started experimenting with them, their workings were often counterintuitive based on my MOSFET upbringing.
Too Little...or maybe Not?
Hi Michael!
Mark(MarkAudio) did drive his Alpair 10.2 on a small 4 Watt Tube Amplifier - and on other relatively Flea-Powered Amplifiers - so i will take my chance! AND I think Mark is planning a more upgraded(past 90db) driver soon. Or else will there be other drivers available(some Creative SoundSolutions soon coming).
The fun is in the trying and building of good equipment - that gives a sense of satisfaction.
Thanks for your effort in a VERY interresting part of Audio.
Olav
Hi Michael!
Mark(MarkAudio) did drive his Alpair 10.2 on a small 4 Watt Tube Amplifier - and on other relatively Flea-Powered Amplifiers - so i will take my chance! AND I think Mark is planning a more upgraded(past 90db) driver soon. Or else will there be other drivers available(some Creative SoundSolutions soon coming).
The fun is in the trying and building of good equipment - that gives a sense of satisfaction.
Thanks for your effort in a VERY interresting part of Audio.
Olav