I only have my earloafs to measureI will try another line input, the one i use now is video, maybe its different?
Get your pc to output 1kHz sinewave with some free software generator, make the divider that hessener advised and measure both 1V RMS to the divider and the stage's output itself. No gen and scope needed and reliable enough to check ballpark levels.
I quickly measured 62.1dB in the rough when I checked the first channel I made with circa 420 HFe input BJTs, so its repeatable. I hope the other channel will balance near enough though. I gathered the small lytics in 25V 105C for the PSU sections but where the heck is my 2nd OPA134 now? The rascal was there in its tube and now its gone! Anyway a local store will stock up rather soon. All my FET input op amps are doubles and I can only swap the one 134 but not listen in stereo even if everything gets ready. BUMMER!
Joachim, a question: Are there shortcomings if increasing the servo's "authority" with lower value injecting resistors?
And one for FDW: I have some 2SA1930/2SC5171 Toshiba. Those are much faster than DH or MJE. Can they be a good bet for avoiding the possible oscillations issue around the regs CCS?
The idea is probably good, but my puter is in one end of the livingroom, and the hifi in the other (separated like poh and food) and i am shure my wife wont like me moving everything around, so i will just live with it, and the sound is fantastic.
Alternatively
D) there are test CDs with tones or you can burn one with a tone and use your CDP as a source.
To be honest, I do not know, I'm not sure if the Ft of 200Mhz (in contrast with the MJE15030/MJE15031's 30 Mhz) is help full. My estimate is, yes it may help, but I have no other reports on this. My opinion is that it is safe to use the 2SA1930/2SC5171 pair, and if it fails/oscillate you can always add the compensation capacitors. My question is, if you have the means to measure oscillation up to 200Mhz, please use them, do not add the compensation, and let me know what happened. O.k. with that, or would you like me to do some simulations? (I'm sure your experience with shunts is, even, larger than mine
).P.s. Their gain of 40 at 100mA is what I would like, as mentioned before, I do think that the very high gain in the Sziklai's pair is a concern.
Last edited:
Their datasheet 200MHz Ft was difficult to verify by simpler means than Agilent specialized lab array of instruments but they should be at least 2 times faster than the MJEs. I am familiar with the core topology also and I will give them a try. I will check oscillation chance easily too, no worries.
They are all compatible (in this application). With no change, the D44H11/D45H11 pair is still my favorite.
The MJE's I have seen oscillate, even though the lower Hfe (you need to know that the mentioned Hfe's and Ft's are a kind of 'ballpark' figure at the 150 mA application). The TIP's I do not know, but there Ft of 3Mhz is below the 5Mhz design goal for the PSU.
And now we have the 2SA/SC's, if high Ft helps, to prevent oscillations, then they may change my mind (and I may make them my favorite). The main difference will (I do think) (in relation to oscillating) be Cob (not Ft), for the D44/D45 this figure is 90/160 pF and for the 2SA/SC it is 26/16 pF (but it may be that the lower Cob enables the device to oscillate at even higher frequencies).
D44H11/D45H11
, , Ft 40Mhz Hfe 100
, , http://www.mouser.com/ds/2/308/D44H-D-111810.pdf
TIP31/32
, , Ft 3Mhz Hfe 20
, , http://www.mouser.com/ds/2/308/TIP31A-D-116282.pdf
MJE15030/MJE15031
, , Ft 30Mhz Hfe 40
, , http://www.mouser.com/ds/2/308/MJE15028-D-110804.pdf
2SA1930/2SC5171
, , Ft 200Mhz Hfe 100
, , http://www.mouser.com/ds/2/408/7654-58852.pdf
, , http://www.mouser.com/ds/2/408/7870-24209.pdf
P.s. In an earlier comment I said that I thought that the 2SA/SC has a low 100 mA Hfe of 40, I have to take that back (wrong information source at that time) the 'official' Toshiba datasheet gives a figure of 100.
Last edited:
Thank you
So are you inclined to believe higher Cob might be better ?
No, I do not
but in this (and exactly this) situations, it may be that a higher Cob is more preventative towards oscillation, and then again, it may be the other way around. That is why I am happy to someone using high Ft low Cob transistors in the PSU (as I told Salas (at the least tried to tell (o.k. now I am over-explaining things (I got to stop (now ))))). My initial guestimate was, use medium Ft medium Cob transistors, given the fact that this would not lead (ever) to oscillation into the 100's of MHz's, that would be bad, most people would not be able to spot those. As you can see (I hope) a lot of thought goes into these things, and still one is not able to mate the 'perfect' choice P.s. Please make next a long question, for a short and easy answer
Sorry what is Cob? you lost me....
I don't know if I have any of those 100 Megamagic things in my R2
It sound pretty good to me still. ? would Wirevound 120Homs resistor make it? worst better no change (please tic as applicable)
Another thing I have slowly been getting same Diotec BCXXX40 so far those have much tighter Hfe match than any maybe be worth ordering those for next GB
I don't know if I have any of those 100 Megamagic things in my R2
It sound pretty good to me still. ? would Wirevound 120Homs resistor make it? worst better no change (please tic as applicable)
Another thing I have slowly been getting same Diotec BCXXX40 so far those have much tighter Hfe match than any maybe be worth ordering those for next GB
It was defined as a 'High ESR' or otherwise 'Low cost' capacitor. This was a mistake, next time I would specify a (greater than) 500mOhm ESR or series resistance (this is more specific
). See also PradiseBuilders #1403 Capacitors bad vs good.These are the most important/relevant messages regarding PSU and Pre-Reg.
- Mpp #4375 PSU-pre-regulator.
- Mpp #4610 V2 Schemas UPS and Amp.
- Mpp #6506 CCS fine-tuning.
- Mpp #6462 PSU with my notes.
- Mpp #6809 Do not try to feed the CVS of the CCS of the shunt with a regulated power supply.
- Mpp #7127 More about transformer selection.
- Mpp #7635 Single and dual transformer wiring (also corrected drawing) (See also #7733).
- Mpp #7733 Grounding (PSU, RIAA and Player).
- Mpp #7810 35V PSU for the CroMagnon.
- Mpp #7830 The PSU explained.
- Mpp #8386 My resistor recommendation’s.
- PradiseBuilders #13 Schema's and assembly guide.
- PradiseBuilders #155 Vdc input voltage minimum simulated.
- PradiseBuilders #970 PSU oscillates; posible solutions?
- PradiseBuilders #983 Compensating the PSU for oscillations.
- PradiseBuilders #1173 Fixing oscillations (up to #1182).
- PradiseBuilders #1322 Fuse .
- PradiseBuilders #1387 Updated Paradise R3 assembly guide (Also German).
- PradiseBuilders #1403 Capacitors bad vs good.