The simplistic Salas low voltage shunt regulator

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Salas

Salas

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RCruz said:
Hi Salas

I am afraid to be overdoing it but I could not resist... After 24h burning, the V12R are now really showing it´s claws.... very good detail without any sign of agressiveness but retaining lower mid and bass presence.

Sweet
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Nice. Had same description feedback from a friend on a double mono too. Looks like V1.2R will graduate official recommendation. Anybody else tweaking to R?
 
RCruz

RCruz

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Good

IMO vref cap has much influence in Tone.

Output cap influences definition.

I am using 33u // 1u film + 0.25r in this case

I will try other values (47u // 4u7 + 0.25r) and report the differences.

I believe it would be good to try 22u also but I am not sure it will be stable.

Hi Mikvous.... Do you have everything inside the same case ?

What are the brand of the caps you are using for vref and the output ?
 
Salas

Salas

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Now, you are charged to find the best subjective combination of Vref film cap quality type, and output system caps quality types as a coherent whole, not changing from safe recommended values +/- 15% for the members to know in the long run. I believe this is your forte. What about that?

P.S. ESR no less than 0.35 @ 100kHz.
 
merlin el mago

merlin el mago

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Salas said:
I evaluated some easy changes on V1.2 and I think they come across subjectively in a positive manner. At least on my 61dB Low MC phono. Pretty stable on the scope also. So I am calling the usual suspects with builds in hand to evaluate and confirm or not on their client applications. Lets call this the V1.2R(revisited) beta test. The changes are two. First the 33p-1k step circuit is deleted and the BJT error amp's base resistor is made to 1k. Second, the output network across the force lines becomes a combination of one electrolytic, a resistor and a film capacitor. Its not crucial to change the value of the Vref film capacitor or the value of the output film capacitor in existing builds for testing. Only to add the 47uF and change the Zobel's resistor to 0.22R. I attach an example. If you fancy beta testing, let me know your feedback.
Click to expand...

RCruz said:
Hi Salas

I am afraid to be overdoing it but I could not resist... After 24h burning, the V12R are now really showing it´s claws.... very good detail without any sign of agressiveness but retaining lower mid and bass presence.

Sweet
Click to expand...


Hey guys,

Congrats:)

Cheers

Felipe
 
RCruz

RCruz

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Salas said:
Now, you are charged to find the best subjective combination of Vref film cap quality type, and output system caps quality types as a coherent whole, not changing from safe recommended values +/- 15% for the members to know in the long run. I believe this is your forte. What about that?
Click to expand...

I am already working on that.

i am actually using BG for the 47u but I will also experiement with Silmic II and Cerafines.

For the film I will try Mundorf MKP, Sonicap and Audyn cap.

With these I will be able to determine subjective individual effects so everyone can "cook" the pretended result.

Hi Felipe..... I had some difficulties implementing V12 because the distance between Film output cap and the Mosfet is critical but This one is as stable as V1 and perfectly noiseless... And the gains in detail relative to V1 are substantial.
 
Salas

Salas

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I have used the Panasonic FC 63V 47uF 0.342 @ 100kHz ESR standard in combination with the Zobel resistor. Keep in mind not to venture far.
 

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RCruz

RCruz

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Yes... I understand that we must not use Rubycon ZA/L there but Silmics and cerafines might do good.

Silmic has that wonderfull bass / upper bass but adds some grit to the sound.... Cerafines might be very good.

As for the BG.... it is still burning and getting better over time so I will wait.... nevertheless BG are almost unobtainium so we must search elsewhere.
 
klewis

klewis

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Joined 2007
Hi Salas,

I have the V1.2 reg up and running again with 70 volts in and a few modifications for the higher Vin - 6.8k R14 and R4, changed Q9 and Q2 to BC546C from BC550C, but it still seems seems to be making too much current.

I've attached my voltage readings. Your thoughts please.

Thanks,

Ken
 

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Salas

Salas

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Making 70.6-70.1=0.5V over R1, smells oscillation to me. Should be about 0.61V for a BC560 there. Does the LED glow normally bright or rather dimly? That is tell tale for problem very high in frequency. Q3 it will be better off with a mini sink. Could be at 180mW with your Vo if your 5457 is 4mA for instance. That would make it drift Vbe a lot (also has a toll on Vref drift) and be unreliable in the long run. You can test delete C1, R8 (lifting one leg will do it) and put a 47uF across force output without removing the output Zobel, that will make it V1.2R that is behaving differently and see if its steadier in your layout with those FQP Mosfet types.
 
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