The simplistic Salas low voltage shunt regulator

[RCruz]

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We are not talking about cross-overs here, but about a power-supply...

I am not sure but I am experimenting.

In the V1, vref cap plays a determinant part in the tonal presentation (when feeding a high gain preamp).

I guess in V12 we can get similar results.

 

[merlin el mago]

I mind there is no discussion about caps, each one can try & select wich one cap is the best (money & subjetive sound) for him.

 

[RCruz]

Of course it all depends on personal taste and compatibility with the rest of the equipment.

I am going to use salvaged caps from a previous experiment.

 

[gjfim]

Hi THKL

Thanks for the great work on the PCBs. I will be happy to share the cost of manufacture of PCBs.

One question- If I am not mistaken, the pin-out of the 2N5457 that you use seems to have center pin drain. Fairchild and On Semi devices seem to have different pin-out, with center pin source. If I am not mistaken, then can you please tell me the manufacturer of the 2N5457 that you use?

Thanks
Gary

 

[RCruz]

yet more confirmation that an amp has just one job to do, to connect the PSU to the receiver.

The quality of signal arriving at the receiver is determined significantly by the effectiveness of the PSU.

This sumarizes my ideas about the psu "signature".

Caps are important even in PSU designs.

 

[tubo]

Is it the 3LED CCS? Shoot for Iset=2V/Rset roughly.

yes it is the 3led ccs. here is the attached scheme...will this reg work for my particular application which is 5v 3amp?thanks

 

[tubo]

pls recommend a 1.8v green led for my application..thanks

Digi-Key

 

[Salas]

You miscalculated. You meant 0.6R for 3A, not 6R. Must be a 15W resistor well ventilated. Use 2V LEDS since you got over 4V VGs, will come handy. Just any LED that has 2V Vf spec and can handle at least 10mA will do. That link is SMD capacitors by the way.

What is that thing drawing 3A at 5V? You must be very careful about dissipation, get a 0.56R, see the voltage drop across, the real current for your build will be exactly VR1/R1. You should need somewhat more left for the elements if you really will draw 3A constantly. Remember that your CCS Mosfet will need dissipate 21W no matter if the shunt Mosfet gives most of it to the load.

 

[tubo]

hi salas,

thanks for clarifying my mistake. the reg will be used for a squeezebox touch power supply. i will have it in a few days and thinking of upgrading it power supply. i think that it only draws 2 amp when the usb is not in use.


by the way the 6v6pre is sounding fantastic...do yo have a scheme for the high voltage reg for that pre?thanks

 

[Salas]

You got a picture of the preamp? Then I got a reg.

http://www.diyaudio.com/forums/power-supplies/134801-simplistic-mosfet-hv-shunt-regs.html
http://www.diyaudio.com/forums/grou...mpler-simplistic-design-salas-group-buys.html

 

[tubo]

yes i do ill post the pic as soon as i get home. it doesnt look nice but it sure does sound very nice...ive built a couple, one for my brother.my build looks crappy and the wiring is messy.ill make a nicer one as i ordered parts to accommodate the hi v reg.and do it justice.

im using mine with a lightspeed attenuator.(i also want to put ur regs on my dac, cdp, and the lightspeed)

thanks.

 

[Salas]

Is it the 6V6 in gain or buffer mode? Remember to show in its tube section original 6V6 pre amp thread too.

 

[tubo]

here's some pics,

its the 6v6 in gain stage mode.i haven't tried the buffer yet. the dac and the lightspeed is in one box.

 

[Salas]

Are they new Tungsol? Cant see well but they have the tell tale crooked bottles it seems. Hey, your wooden style isn't that bad, why you said they look bad.

 

[tubo]

the ones on the pp 6v6 amp are new production tungs but the ones on the 6v6 pre are GE's i had lying around. those GE"S outperformed the current production Eh 6v6 in my setup.

it doesn't look as good as others have built. and the wiring inside is messy. ill post more pics on the 6v6line pre thread....

 

[AndrewT]

Hi Salas,
for that high CCS current >2A would it be useful to go to 4LEDs (~7V to 8V) to drive the CCS FET?
I think you will find a more stable FET voltage which in turn will result in a more stable Vr1 voltage.

I would also recommend at least 2 power resistors for that current. Keeps the current density around the resistor pads lower and thus less of a parameter change in the copper traces as they heat up.

For the 3A supply, 4LEDs @ ~7.2V and Vfet=4.1V leaves 3.1V as Vr1.
Now a pair of 2r2 power resistors pass ~1.4A each (4.3W each requiring >=7W Pd). A third trimmer resistor (~15r) can be added to give the desired CCS current if it needs to be higher.

 

[Salas]

That's very good practical thinking, makes it more workable at such currents and I agree. Also 2V greens are easier to chance finding, and 2.7R//2.7R plus a trimming parallel. Vgs or LEDS or power resistors will never be exact in any build.

 

[RCruz]

I mind there is no discussion about caps, each one can try & select wich one cap is the best (money & subjetive sound) for him.

When I first swapped the v1 shunt by the v12 on my phonos, I imediately got a much more detailed and coherent picture but lost some of the previous size and inpact.

Based on my previous experiments with vref cap on v1.... (Type of cap and capacitance matter enourmously in this case).... I replaced the small size inexpensive Audyn-Cap MKP-QS 10u 400v by the also inexpensive and very ugly looking LCR FP-CA-AU 10u 630v with BIG black plastic case.

I was not prepared for this change.)... I believe these caps must burn for 100h before full acessment but right "out of the box" they produce a full bodied sound with impressive bass extension allied to good trebble detail.

After all caps matter in this case. (I am using this shunt in an analog amp.... when powering a digital circuit things might not work this way of course)

 

[pidesd]

i agree that the output zobel cap makes a HUGE difference. when i went from electrolytic alone to the zobel with a cheap 4.7uf cap but bypassed by a russian ft-3, i could believe the level of detail i was getting out of my cheap mp3 player, but it didnt sound right (probably due a bad reaction of the bypass). i finally settled for a single cheap cap in the zobel, which is ahead of the electrolytic alone. if only they made bigger size than .47uf ft-3...

so in my opinion i guess it s worth spending a bit for a good output cap.

rcruz, have you tried those obbligato you talked about earlier,IIRC?

i m interested in trying those

Obbligato Premium 10.0uF (250V) | Diy HiFi Supply

 

[Salas]

So you used 4u7 MKP (or MKT?) in seriers with 1R across output and you liked it better than the solo output lytic, if I understood correctly? Ricardo was talking about the voltage reference capacitor.