Sorry Rcruz, just using this example, @salas this is what I was talking about in the gb thread re film bypass on output and you said not to do it due to oscillations, I'm confused as you don't mention anything here. So is good idea, bad idea or what?
I like reading your impressions salas, because you use more music I'm familiar with, rather than the usual audiophiles guff
That is V1.2R. If you bypass straight on V1.0 or V1.2 you will get it oscillating. The 1.2R has not the step feedback network of 1.2 and its not a V1.0. Note this is a complex termination network for R exclusively, with defined values. There is resistance added in the film to keep the total impedance where it works as a whole with the reg's open loop. Its not a typical bypass.
Ok got it, as with many wide bandwidth amps it needs to see some resistance so I gather padding the output wih a small resistor would do the trick, Oscons in place of the electrolytic are a nogo as well I imagine? One of those places that normal good quality caps are preferred to high quality low impedance caps whether they be film, electrolytic or ceramic
I will go have a read again now and compare the 2 circuits, I wonder how easy it would be to modify the reg for 1.2v functionality with a small piece of perf
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For vref I am using 10u Obbligato Gold (much better overall than small Audyn cap or even AmpHom). I do not recomend bypassing this cap as it can create phase distortions producing audible deffects (like loose focus and confused sound) So for Vref one should choose the best possible cap.
For output 47u, I used a 47u BG std 50v, very close to the mosfet. A good alternative would be a Nichicon for it´s very good bass response.
Bypassing this is a 4u7 Sonicap in series with 0.25r (4 x 1r metal film)
Tone was very good but it lacked some "snap" so I bypassed the 4u7 with a MKP 1837 0.1uF and now I have those startling transients again
Bypassing this film cap does not create any confused sounds.
If I used a 1u instead of the 4u7, I would recomend 0.022u for bypass instead of 0.1u.
Please note that I am using v12r on my phonos.... I do not know how it should perform powering a dac chip or other digital aparatus.
Maybe if I wanted to use the shunt to power the servo chips in my CDP I would not notice the vref cap effect.
For vref I am using 10u Obbligato Gold (much better overall than small Audyn cap or even AmpHom). I do not recomend bypassing this cap as it can create phase distortions producing audible deffects (like loose focus and confused sound) So for Vref one should choose the best possible cap.
For output 47u, I used a 47u BG std 50v, very close to the mosfet. A good alternative would be a Nichicon for it´s very good bass response.
Bypassing this is a 4u7 Sonicap in series with 0.25r (4 x 1r metal film)
Tone was very good but it lacked some "snap" so I bypassed the 4u7 with a MKP 1837 0.1uF and now I have those startling transients again
Bypassing this film cap does not create any confused sounds.
If I used a 1u instead of the 4u7, I would recomend 0.022u for bypass instead of 0.1u.
Please note that I am using v12r on my phonos.... I do not know how it should perform powering a dac chip or other digital aparatus.
Maybe if I wanted to use the shunt to power the servo chips in my CDP I would not notice the vref cap effect.
Thanks for sharing Ricardo
Salas,
I put the 10k in at Rd. It gives 71.3Vout with 71.8Vin. So I should start raising the value of Rd?
Ken
Salas,
Darn, you're good! Paralleled 20k with 10k to get measured 6.61k and got 57.4 vout. Rock solid after about a minute. Excellent.
Will this technique work with V1.2r? I will need to make new boards anyway.
Best regards,
Ken
You got to know the IDSS of the JFET used first of all Ken. It will be roughly 70% what it is for 9V test when in position for a K170BL. So you project a Vref resistor (Vout-0.6)/IK170. If you can use a bigger film cap across the resistor than before is better, due to its lower now. Its OK for all versions. 1W up resistor(s) for your Vo.
Quang Hao GB Salas Low shunt regulator
@Salas
You said in the Quang Hao GB Salas Low shunt regulator: "Has been modelled with Pana FC 0.3-0.35 Ohm 100Khz impedance for 130deg loop stability margin. For few questions (if not really covered before) loop in the original development thread."
These specs are needed for all lytics caps?
Pana FC 220uF 100khz only 350 mOhm 6.3 & 10V...I have on hand 63V 100khz 130 mOhm it's ok?
Pana FC 1000uF 100khz 36 mOhms it's ok? because I have on hand these.
For 47uF also be a good choice Pana FC 47uF/63V 342mOhms?
Digi-Key - P10340-ND (Manufacturer - EEU-FC1J470)
@Salas
You said in the Quang Hao GB Salas Low shunt regulator: "Has been modelled with Pana FC 0.3-0.35 Ohm 100Khz impedance for 130deg loop stability margin. For few questions (if not really covered before) loop in the original development thread."
These specs are needed for all lytics caps?
Pana FC 220uF 100khz only 350 mOhm 6.3 & 10V...I have on hand 63V 100khz 130 mOhm it's ok?
Pana FC 1000uF 100khz 36 mOhms it's ok? because I have on hand these.
For 47uF also be a good choice Pana FC 47uF/63V 342mOhms?
Digi-Key - P10340-ND (Manufacturer - EEU-FC1J470)
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