I'm good with the input stage load/gain - output stage bias thing but, if I stick with a stock Aleph style CCS, what would you say the difference would be? Would it be worth the effort to try to develope a good SRPP like you have or is the aleph circuit up to the task in classic Pass style?
I'm good with the input stage load/gain - output stage bias thing but, if I stick with a stock Aleph style CCS, what would you say the difference would be? Would it be worth the effort to try to develope a good SRPP like you have or is the aleph circuit up to the task in classic Pass style?
Papa wrote in post #120 - plain mosfets , used in previous Aleph series , have Vgs window of ~4V , where you can easily squeeze in small governor bjt .
these new jfets , even if biasing scheme is same as for mosfets , have Ugs window of just ~1V25 . if you try to squeeze small governor bjt there , it will starve ........ if it's starving - it isn't functional ..... at least not good enough .
so - some other biasing scheme is desirable .
ZM,
Are you talking about the ZTX550 for instances in Aleph J CCS, or ZTX 450's closer to output? Or BC556, 546 in Babelfish J.
The BA-1 uses 2SK170 in front end CCS. I figure 2 here will get more current to 2SJ's possibly lowering drain resistor. Not sure about the ZTX on the back end however. Had not considered that.
The ZTX450's in the Mini-A did not seem to complain with R100's.
Are you talking about the ZTX550 for instances in Aleph J CCS, or ZTX 450's closer to output? Or BC556, 546 in Babelfish J.
The BA-1 uses 2SK170 in front end CCS. I figure 2 here will get more current to 2SJ's possibly lowering drain resistor. Not sure about the ZTX on the back end however. Had not considered that.
The ZTX450's in the Mini-A did not seem to complain with R100's.
well - I'm talkin strictly about little bjt governing Aleph CCS ( which is output CCS , what else ) ; sorry - I wasn't clear enough .
anyway - besides that I'm babelfishing Papa's words , I also said , as my personal opinion : "at least not good enough"
it'll work in 1V25 window , but not good enough ; say that little critter is riding on pretty big seesaw , hanging on tight rope
1V25 isn't comfortable C-E voltage for proper function
anyway - besides that I'm babelfishing Papa's words , I also said , as my personal opinion : "at least not good enough"
it'll work in 1V25 window , but not good enough ; say that little critter is riding on pretty big seesaw , hanging on tight rope
1V25 isn't comfortable C-E voltage for proper function
Well, as I said, I was interested in using the IRF240 or similar part in a stock style Aleph CCS with the Semisouth JFET only on the bottom. Both to avoid this low C-E voltage problem but also to crerate an improved Aleph style amp. It's easier and more orignal Pass this way!
I'm also willing to work out a method of making the SRPP J2 style amp??? And/or the Aleph CCS mod'ed with for the JFET might also be only a small addition to the parts count??? Maybe a buffer transistor with the drain of the "govonor" feeding the Base and the Emitter driving the Gate of the CCS JFET? The govonor Collector would then be a Vbe higher. That would probably do it???
I'm also willing to work out a method of making the SRPP J2 style amp??? And/or the Aleph CCS mod'ed with for the JFET might also be only a small addition to the parts count??? Maybe a buffer transistor with the drain of the "govonor" feeding the Base and the Emitter driving the Gate of the CCS JFET? The govonor Collector would then be a Vbe higher. That would probably do it???
it'll work in 1V25 window , but not good enough ; say that little critter is riding on pretty big seesaw , hanging on tight rope
1V25 isn't comfortable C-E voltage for proper function
What about 2V for 2SK1530-Y, is it comfortable enough?
Do you think there is any benefit of using 2SK1530 vs the default 240?
One I can think of is that the lower Vgs of 2SK1530 allows the output to go closer to rail voltage, so either higher output power or lower dissipation with less transformer and less of everything.
say that 2V is lower margin we can use as "safe"
my ( as always - humble 😉 ) opinion is that rail-to-rail thing is/was never issue with this type of amps ; wasting so much energy , then thinking about some 5-10% of it is ..... just boresome ;
then - there is xconductance issue ; there was always need to substitute one pair of laterals with at least two pairs of verticals ;
even if 1530 certainly isn't lateral , so that part of comparison isn't valid - I can't see any benefit in using them instead of IRFP , at least in this area of Iq ; I can assure you - IRFP150N , honking at 40-50W of dissipation sounds pretty good
just another humble Q. for Papa
Papa - have you recorded curves for R100 and R550 - in area interesting to us ?
Papa - have you recorded curves for R100 and R550 - in area interesting to us ?
yup ;
but you remember that little critter , first responsible for that AC gain - will work with halved voltage
but you remember that little critter , first responsible for that AC gain - will work with halved voltage
ZM dumpsterdiving ...... again
bump
Papa - have you recorded curves for R100 and R550 - in area interesting to us ?
bump
Papa - do you have recorded curves for R100 and R550 - in area interesting to us ?
deja vu ..... Mighty ZM ..... again in Papa's disgrace
With 1.2kV or 1.7kV spec, am I the only one that's thinking of building a amp for Stax ESL headphone?
reading the KGSS DIY amp, it uses direct coupling output without transformer, and getting BJTs that can take high voltage and low capacitance was the most important criteria for part selection, which the SiC parts seems to fit.
reading the KGSS DIY amp, it uses direct coupling output without transformer, and getting BJTs that can take high voltage and low capacitance was the most important criteria for part selection, which the SiC parts seems to fit.
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