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B1 Buffer Preamp
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Old 13th November 2008, 12:59 PM   #911
jackinnj is online now jackinnj  United States
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B1 Buffer Preamp
Manhattan style B1:

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at Vcc's from 10 to 32V

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Old 13th November 2008, 01:51 PM   #912
maxlorenz is offline maxlorenz  Chile
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Hi Jackinnj,

Quote:
You really don't want to use a switcher -- note that 1/2 VCC is injected onto the gate and any noise on the VCC node will degrade performance.
I use a gyrator based regulator named Teddyreg on my two B1 units and in my next one I plan to use it after a SMPS that I got from a broken printer. Please look at this:

http://www.acoustica.org.uk/

Scroll down to "using 3-pin regulators, part 2"

Cheers,
M.

PS: do your FETs get hot at 32V?
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Old 13th November 2008, 03:03 PM   #913
troystg is offline troystg  United States
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Quote:
Originally posted by maxlorenz
Hi Jackinnj,



I use a gyrator based regulator named Teddyreg on my two B1 units and in my next one I plan to use it after a SMPS that I got from a broken printer. Please look at this:

http://www.acoustica.org.uk/

Scroll down to "using 3-pin regulators, part 2"

Cheers,
M.

PS: do your FETs get hot at 32V?

If the TeddyReg can handle 48VDC input I have a box full of switching PS sitting in storage looking for a home.
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Old 13th November 2008, 03:06 PM   #914
jackinnj is online now jackinnj  United States
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Quote:
Originally posted by maxlorenz

PS: do your FETs get hot at 32V?
I will put the temp probe on them this afternoon. at 32V it's drawing about 8.2mA = 250mW. For a single sk170 Max Pd is 400mW.
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Old 13th November 2008, 03:14 PM   #915
giantstairs is offline giantstairs  Spain
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Quote:
Originally posted by jackinnj
[B]Manhattan style B1:
and Manhattan budget!

where'd you get those Spragues? and more importantly, how does it sound?

i'm getting ready to build a b1 but haven't decided on the caps... any more budget minded suggestions? would the Obbligato caps from Diyhifisupply work well?
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Old 13th November 2008, 03:35 PM   #916
jackinnj is online now jackinnj  United States
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Quote:
Originally posted by giantstairs


and Manhattan budget!

where'd you get those Spragues? and more importantly, how does it sound?
The Spragues I purchased for a project which needed a high quality sample-hold -- they are polycarbonate. I didn't have a polystyrenic of such high value (10uF). I have also used them with true RMS converters. I bought them from a distributor who was flushing his inventory of bulky discretes a couple years back so have a box of them!

Polycarbonates -- the jury is all over the place on how they sound compared to polypropylene, PET, polystyrene etc. Some really like the sound of the Russian PS caps.

Mouser used to carry this value Spragues.

It isn't "sounding" anything at the moment. I am going to use it as a buffer in a JFET preamp. At the moment there are some unresolved issues, however...

One thing about filtering the output of the cap multiplier -- or 3 pin adjustable regulator -- bypassing the adjust pin knocks down noise, but it also worsens transient response.
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Old 13th November 2008, 03:48 PM   #917
juma is offline juma  Germany
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I can confirm that polycarbonate film capacitors (i've got a bag of them - Philips MKC) are very neutral sounding.
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Old 13th November 2008, 04:01 PM   #918
Gooch is offline Gooch  United States
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Quote:
Originally posted by steenoe


It can run on a voltage up to 24V.
What you really ought to want, is a shuntreg
Here and onwards

It simply sounds crisp, transparent and very enjoyable.

Thanks Steenoe for pointing me to that thread good stuff the reg looks very cool.
You wouldn't have one of those shunt reg PCB that you might want to part with?

Cheers
Dave
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Old 14th November 2008, 01:16 AM   #919
maxlorenz is offline maxlorenz  Chile
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Dear Jackinnj,

Thanks for the tip about Adj pin. I have also put a zener instead of L317 before the gyrator and it sounds good to me. I have not compared the two version face to face yet...

Dear Troystg,

Quote:
If the TeddyReg can handle 48VDC input I have a box full of switching PS sitting in storage looking for a home.
48V is too much for the LM317...see datasheet. But you can lower it a bit with high W resistor first, I guess...even lower ripple.
I have used it safely with 34Vin.

Cheers,
M
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Old 14th November 2008, 02:58 AM   #920
pinkfloyd4ever is offline pinkfloyd4ever  United States
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ahh the B1 can handle more than 24V? Cause I'm building a gainclone (i know wrong thread) which will have about a 30V supply...does it have to be regulated?
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