B1 Buffer Preamp

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#901
Re: Re: Re: B1 born in the land of Oz

rabbitz said:


I meant "did". You had me going there as I'm partially disabled and tend to hit the wrong keys or type slower than the brain so I miss out on key words.

When I adjusted the offsets to about the same numerically (1.4mV), even though one was +ve and the other -ve, the rails were quite different. I'm trying to remember but it was something like +10.1V and -9.4V so I decided to keep the rail voltages the same and have and extra 1.3mV offset which is no problem.

Salas

The next one I build I'll try and get them closer, but hey, a few mV here or there is not going to upset me.
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Hi
I have the Anthony Holton NXV200 amp and would like to build B1,where do you get the parts in oz?
 
#903
Gooch said:
...I have another question I have an old Dell laptop power supply output is 20v DC that should work? Or should I get something at 18v DC?...
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Your Dell charger is likely a fairly well regulated 19.5-20V or so. There will be almost no loading on it as it is likely 3A-6A rated. I would position it a good fisical distance away from the B1 as it will emit switching noise your systen will pick up. Also filter it better with some film caps. 😉
 
#904
Try explaining it to the new bald headed boss
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udailey, how did you know?!?! We just walked through a discussion of our December scheduling, which will be hectic. I asked him where my time off comes into the schedule because he has me involved in just about every hot project. :hot:

Everyone: I'll have some photos up soon of my B1 build as it progresses. I've already got the main board populated with caps, resistors, relays, etc.

I spent last night on getting my bridge rectifiers and caps populated...coming together nicely. This weekend will probably be spent in the garage drilling holes in the chassis on my drill press.
 
#905
flg said:


Your Dell charger is likely a fairly well regulated 19.5-20V or so. There will be almost no loading on it as it is likely 3A-6A rated. I would position it a good fisical distance away from the B1 as it will emit switching noise your systen will pick up. Also filter it better with some film caps. 😉
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You most have one of those power supplies you pretty much nailed it. I order the parts I didn't have on hand now I have to come up with some type of chassis for it.

Thanks again for all the help 🙂
 
#907
Gooch said:
You most have one of those power supplies you pretty much nailed it...
Thanks again for all the help 🙂
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I might have a few around here... I used to work in the off Line switcher bis. Used to build protos and demos. You can find some that are 8-10A. Save those for a power amp 😉
Now I play with DC-DC stuff. 12V to 1.2V :xeye: Not much use except for putor stuff :whazzat:
 
#912
Hi Jackinnj,

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.
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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?
 
#913
maxlorenz said:
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?
Click to expand...


If the TeddyReg can handle 48VDC input I have a box full of switching PS sitting in storage looking for a home. 😀
 
#916
giantstairs said:


and Manhattan budget! 🙂

where'd you get those Spragues? and more importantly, how does it sound?
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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.
 
#919
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,

If the TeddyReg can handle 48VDC input I have a box full of switching PS sitting in storage looking for a home.
Click to expand...

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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