Ultrasimple SIT PP amp from BAF , or SIT Beast with a Thousand PSUs

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#222
Antoinel said:
generg. Is your output test circuit wired exactly as shown in post #4? The AC impedance of the bias batteries shown in the schematic is practically zero Ohms. Thus, ripple e.g. at the +23 V rail appears almost intact in amplitude and phase at the gate of the SIT. The ripple signal between gate and source is equal to zero V and so the SIT will not pass ripple to show at the output; to be heard.
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yes Antoinel, it is the circuit of post #4.

when it is not the main power supply it must be the bad location of my Edcor,

at the moment I am too lazy to change this….. especially when Nelsons solution and thoughts are coming soon I prefer to take a rest in the sun (or is it darkness)
of my incomplete solution…..🙂

:cheers:
 
#223
generg said:
…...after having some days ago big differences between the gate voltages for the SJ and SK (1.3A and zero offset), 11.9V and 8.3V means 3.6V difference,

http://www.diyaudio.com/forums/pass...f-sit-beast-thousand-psus-19.html#post3680875

I looked for a better pair and I have now 8.3V and 9.2V at the gates.

So difference is only 0.9V, of course worse than Nelsons 0.6V value. He is the Matching King! 😀

But maybe this is not important for the sound, only for measuring freaks, who knows at the moment…….

🙂
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I replaced the 9 V batteries on the home smoke alarms, and measured the open circuit voltage of the fresh and used ones;
  • Two new alkalines at 9.22V
  • Three new alkalines at 9.44 V
  • Used at 9.08 V[Li], and alkalines at 8.8V ,8.8 V, 8.7V, and 8.7 V.
  • I also have two rechargeable NiMH 9 V batteries [170 mA-Hr]. They measured at 8.95V, and 9.01 V.
It so happens that the specific bias to your circuit maybe as simple as two 9 V batteries, new and custom discharged to suit; with additional electrolytic caps across them to lower their internal resistance. What will the current draw be for the reverse-biased gate-source junctions of the SITS; microamps? There will be a slow drift of output DC offset;which maybe acceptable.
 
#231
I got patient…. so many nice amps here to hear and to change every week…😀

F3, F4, F6 with k3 dominance and with k2 neg Phase versus k2 pos Phase, F4 with auto former or BA-3 frontend, Babelfisch J2 and ……and….

no dullness….

Pres are also circulating… B1 with caps (the ones recommend by Nelson, wonderful!) and TKD Pot alone, and UGS3 and two DS1822 or classic quadro pot and….and looking for a Muse solution…

‚l‚t‚r‚d‚r‚V‚Q‚R‚Q‚O�@“dŽqƒ{ƒŠƒ…�[ƒ€ƒLƒbƒg: ‘g‚Ý—§‚ăLƒbƒg �HŒŽ“dŽq’Ê�¤ “dŽq•”•i ƒlƒbƒg’Ê”Ì

(thanks dsdjoy for the link 🙂 )
so no hurry…….there are enough sharks in the water! 😀😀
 
#234
Yeah makes more sense 🙂

Have you tried those?
I have a bunch of them from when I wanted to make my lightspeed arduino controlled, but I gave it up when I got my DCB1... Never thought to try them as plain pots... It should be interesting if they sound nice 🙂 I m in the middle of planning a stepped attenuator, and I would very much like to abandon it 😀 Ordering some linear precision wirewound to test too for that matter...
 
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#238
dimkasta said:
Yeah makes more sense 🙂

Have you tried those?
I have a bunch of them from when I wanted to make my lightspeed arduino controlled, but I gave it up when I got my DCB1... Never thought to try them as plain pots... It should be interesting if they sound nice 🙂 I m in the middle of planning a stepped attenuator, and I would very much like to abandon it 😀 Ordering some linear precision wirewound to test too for that matter...
Click to expand...

Results for the DS1882 are a bit confusing.....

They seem to soften the sound, suck a bit of life out, the quad pot is much better....

But maybe the surrounding delivering the 5V digital and -6.8V and +6.8V for the analog part is of more importance than I thought.....

I hope Muse behaves better....

Sorry for OFT, it is only filling waiting time....😀
 
#239
dimkasta said:
Doesn t that affect output impedance? Newb greedy boy alert 🙂 any reading you might suggest?
Click to expand...

voltage to current to voltage conversion

sometimes you don't need to care about output impedance ....... or just put any convenient buffer

:clown:


dunno yet , regarding buffer - ear will decide , not measuring

edit : G, fill that waiting time with some red , sharing that way what's most important ..... easiness ...... 😉
 
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