I tried to connect Peerless 16688 (impedance ratio 150:4) in my Ironamp and the result is very good and very difficult to return to hear Edcor CXSE25-8-150
Now, I can built a Ironamp with all Peerless transformer
Magic Moment: Altec 9476A Monitor Amplifier
Now, I can built a Ironamp with all Peerless transformer
Magic Moment: Altec 9476A Monitor Amplifier
I will use Tango FG-50S for my SIT Nemesis, I just want to build Ironamp with all Peerless transformer because I very lucky to have IPT and OPT Peerless
About R core for this amp, I will see....
I built the second Ironamp with all Peerless transformer (IPT: 15280, OPT: 16688) so I called the name is... "PEERLESS"
Always pleasure to see your diy amplifiers Nagini & congratulations !
Do in/ out transformers change the final sound a lot and do you like it ?
Best regards
The sound is incredible but I don't have anything to compare it to. I'm hoping Father Pass remedies that in March!
Regards,
Dan
May I ask you guys some question on why you used the 2sk180 the way you used it ?
My target: See what I can get out of it with max. reusage of my existing setup, which is a fixed bias, 801A/300B amp, IT coupled with nice 1:1 nano IT. It would ne nice to maybe change the OPT, but besides this...a 2sk180 could do the job of a mighty 211 or even bigger triode...
Sooo, I had a look into the data sheet:
http://www.amplimos.it/images/2sk180 datasheet.pdf
What struck me are a couple of things:
- mu is dependant of Vds with approaching 300V and 100mA maxing out at a mu of approx. 18...above 300V/100mA its constant...which is desirable I guess to have a constant mu...think of distortion
- Input capacitance is falling quiet significantly when raising Vds: 1V: 3000pf, 100V: 2000pf, 400V ??? I would guestimate clearly below 1000pf, maybe 500 pf ?
- Maybe its just my old eyes, but the HV curves look pretty much more linear to me than the LV curves, no ? I still would say the usable area should be from -10V to -30V only with min. current set at 100mA for the loadline...so I took out my ruler and draw some loadlines....
Being a tube guy, I would shoot for a setting of:
- 420 B+/Vgs
- 350mA current initially, maybe 500mA later, so with 147W initially 50% safe below the 300W of the device (2sk180)
- Bias of around -20V I guess
- Load line at 1300ohm, giving us a nice flat line to minimize distortion and maximize damping factor.
- This gives into a a 6ohm speaker 21W...which is a lot, at the level of a 845 already
Alternative settings:
- Same as above, but 500mA bias at 420V, 630 ohm primary load: 43W
Or a bit lower HV (but this means the variable Mu below 280V will create even more distortion when the signal travels through the loadline/curves):
290V, 500mA, 290ohm primary, 20W power
Does this makes sense ?
I have no pratical experience with this device, so it is a bit unclear to me if the high current, low voltage /low load approach or the approach I just described makes more sense...or something in the middle...maybe someone has already looked into that before ?
What happens when the voltage swings (as the input signals swings) above 600V ? For a tube it does not matter as long as the bias is withing the specs, is this the same with a SIT or is it simply dead ?
My target: See what I can get out of it with max. reusage of my existing setup, which is a fixed bias, 801A/300B amp, IT coupled with nice 1:1 nano IT. It would ne nice to maybe change the OPT, but besides this...a 2sk180 could do the job of a mighty 211 or even bigger triode...
Sooo, I had a look into the data sheet:
http://www.amplimos.it/images/2sk180 datasheet.pdf
What struck me are a couple of things:
- mu is dependant of Vds with approaching 300V and 100mA maxing out at a mu of approx. 18...above 300V/100mA its constant...which is desirable I guess to have a constant mu...think of distortion
- Input capacitance is falling quiet significantly when raising Vds: 1V: 3000pf, 100V: 2000pf, 400V ??? I would guestimate clearly below 1000pf, maybe 500 pf ?
- Maybe its just my old eyes, but the HV curves look pretty much more linear to me than the LV curves, no ? I still would say the usable area should be from -10V to -30V only with min. current set at 100mA for the loadline...so I took out my ruler and draw some loadlines....
Being a tube guy, I would shoot for a setting of:
- 420 B+/Vgs
- 350mA current initially, maybe 500mA later, so with 147W initially 50% safe below the 300W of the device (2sk180)
- Bias of around -20V I guess
- Load line at 1300ohm, giving us a nice flat line to minimize distortion and maximize damping factor.
- This gives into a a 6ohm speaker 21W...which is a lot, at the level of a 845 already
Alternative settings:
- Same as above, but 500mA bias at 420V, 630 ohm primary load: 43W
Or a bit lower HV (but this means the variable Mu below 280V will create even more distortion when the signal travels through the loadline/curves):
290V, 500mA, 290ohm primary, 20W power
Does this makes sense ?
I have no pratical experience with this device, so it is a bit unclear to me if the high current, low voltage /low load approach or the approach I just described makes more sense...or something in the middle...maybe someone has already looked into that before ?
What happens when the voltage swings (as the input signals swings) above 600V ? For a tube it does not matter as long as the bias is withing the specs, is this the same with a SIT or is it simply dead ?
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Ok, i digged deeper and found this nice white paper from Helmut Weigl on SIT at HV...
http://www.roehrentest.de/SIT_EN.pdf
So, he reports of oscillations when going above 300V B+ and advises not to use a 600V device above a bias of 300V when using transformer loaded...he got as well some nice curves in there for the area of 0 to 340V up to 300mA which his tube tester could record....Ok this reminds me of the circuit in the data sheet where they used 275V ...with choke input...
http://www.roehrentest.de/SIT_EN.pdf
So, he reports of oscillations when going above 300V B+ and advises not to use a 600V device above a bias of 300V when using transformer loaded...he got as well some nice curves in there for the area of 0 to 340V up to 300mA which his tube tester could record....Ok this reminds me of the circuit in the data sheet where they used 275V ...with choke input...
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