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howto: replacing the ALWSR pre-regulator by a VBE

Phew! I found a copy of the jpegs of the X12 Ultimate Gainstage that I forgot I had saved on my hard-drive.

I'm still on the hunt for 47uF Elna Silmics though, if anyone knows anywhere I can get them?
 
Thanks for you help chiily and RonR.

Here's a question. Has anyone tried using a 47uF tantalum in the feedback loop instead of a silmic? Is there a reason that tants aren't used here? I'm just wondering because tants are generally considered to sound so good...!

RonR - Glad you're a few steps ahead of me! Please be sure to let us know what they sound like, ok??
By the way, have you got any good sources for oscon SP's? and Evox-rifa mmk's?
 
Hello Si.

You might also send a PM to RichardH here on PFM.

AFAIK he bought a batch of 47uF 50v Silmic II for the SR projects and might have some left.
I purchased a few from him for 10 ALWSR's that I assembled last year - very good price as well.

Dave.
 
Si,

For the numbers you need you would be better going through Richard. I would be just re-selling mine on, whereas Richard I think still has quite a few left to move.
 
Hi, I thought I'd resurrect this thread rather than start a new one.

I want to try using PFM gyrators replacing the pre-regs on a pair of ALWSR's on my Buffalo DAC. I couldn't find any information relating specifically to the gyrators in this application.

So -

1) Whats the best way to connect the gyrators to the regs. I should omit the pre-reg but are there any other components on the ALWSR's I should leave out?

2) How should the gyrator and reg's 0V's be handled?

3) Are the following pin configurations still valid:

1. Link TRS2 to TRGND
2. Link TRIN to SRIN
3. Use TROUT as the Input (instead of TRIN)

Anything else I should consider?

Thanks in advance

Rich
 
A quick background
The ALWSR has a pre-regulator, which is based on a monolithic linear regulator. Through experiments, I discovered that the performance of the ALWSR can be significantly improved by providing it a smoother input containing less high frequency noise.
Just curious, how much lower noise?

As info, WITH the preregulator my pcb has 921 nV (best possible condition) noise which is done with measurements.
More info here
http://www.diyaudio.com/forums/powe...egulator-collecting-facts-14.html#post1986153
 
That's so funny, I saw your name in the DIY section as being the last person to comment on this thread, and I immediately thought "I bet peranders is pimping his boards again...." :D
No, actually. I'll think they will do for some time ahead.
 
Anybody have any ideas on using the PFM gyrators here?

Post #108 above in case you missed it!

Its the 0V returns that i'm most concerned about. The gyrators confuse me slightly here.
 
Yep, I've read the entire thread a few times as well as the original thread. There is no mention of using the PFM gyrator boards, only bug building the VBE onto the SR which I don't really want to do.

Perhaps no one has done this yet. I'll have to experiment later and see if I can figure it out.
 
I am sorry no one i springing to your help here Rich, unfortunatly your treading ground that I have not yet visited.
 
Could gyrators/Vbes be used in case it is needed to drop let’s say 10 or more Volts before the ALW Super Regulator?
 
Yes, and the greater the voltage you drop the better the job they can do. I do this a lot and retain the LM317 pre-regulator on the ALWSR.

If you have a steady current load you could also use choke regulation at the rectifier?

John
 
Oops I just realized I resurrected a 2010 thread..

Thank @john.luckins, this is promising!

I plan to improve the power to the analog outputs of my dddac chips using a bigger than necessary trafo so needing a way to cut down on voltage (I have possibilities to use roughly 14ac/20Vdc after rectification, 20ac/28Vdc or 40ac/56Vdc), and have been looking in the Vbe affair..

Basically needing steady less than 50mA per channel at 12V SR output for the 8V onboard tent shunts.

Yes, choke psu (LCLC) would be possible as I have some parts already, this is really what I was thinking of.
The debate here would be which would be best in my needed application between a single LCLC+2x(vbe+sr+shunt) or two separate windings for vbe+sr+shunt and of course Which Vbe to remain in topic. Any suggestion? Thanks a Lot.
 
I've sketched out a possible solution that I can scan and email to you if you are happy to PM me your email address?

It uses two 12 v ALWSR's with TPR's, 2 X zener based cap multipliers all fed from a single or dual LC/choke regulated supply. That level of filtering eats up the volts a bit and so the 40v AC winding is needed, which through choke regulation provides 38-40 volts on the first filter caps. I'm wondering what chokes you have (current rating, resistance and inductance) as this may change things a lot. I've chosen either a single Hammond 158Q of a two 156R's in series LCLC. I use these a lot.

Looking at the DDDAC site it looks as though there are 3 separate and pretty basic shunt regs on the DAC. I would expect an ALWSR to trounce these for load and line regulation and and maybe even noise but this may be a bit unwieldy!

John
 


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