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Old 25th March 2009, 11:54 PM   #1531
Tea-Bag is offline Tea-Bag  United States
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Default balanced setup.

Didn't someone earlier do a post about using the traditional B1 schematic in balanced operation by using the out's on these tied to a 1 and 2 of XLR? I can't seem to find such a post. Was I dreaming it?
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Old 26th March 2009, 01:06 AM   #1532
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Default Re: balanced setup.

Quote:
Originally posted by Tea-Bag
Didn't someone earlier do a post about using the traditional B1 schematic in balanced operation by using the out's on these tied to a 1 and 2 of XLR? I can't seem to find such a post. Was I dreaming it?

dunno .....

maybe I did ...... maybe not ;

use one stereo B1 per channel ....... one channel of B1 for pos. leg , other channel of B1 for neg. leg

look in PSM LS thread to see how 4 separated buffers are used for balanced operation .

peace of cake .
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Old 28th March 2009, 06:08 AM   #1533
dejanm is offline dejanm  Austria
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Some first reflections on B1 ... Remark: I am talking here about "original" Pass B1 design.

I had some thoughts on power supply. The question was how much to invest in it: whether to go with good shunt reg or to use something simpler or even to go with something very simple - that was the first question ..

So together with a friend of mine I put simple power supply of 18 V DC: transformer -> elco -> standard LM317 Reg -> B1. On the input of B1 I have Nichicon Elco of 15 mF, 25V. On the other side I put together simple battery supply made of lot of AA Alcaline 1,5V batteries. The voltage was the same: 18V DC. I installed a switch so that I can easily switch from one supply to another. And I couldn't really hear any difference in sound reproduction.

Then I increased the battery voltage to 23V. And again I couldn't really hear any difference. I know that THD is lower when the voltage is higher but in real life I cannot make difference ... at least not on the system where I was testing (solid middle of the class HiFi system).

These are some experiences that might help somebody. My personal conclusion is that B1 is made as a simple buffer and that it should be kept simple. Maybe some experiments with input and output caps would be interesting (for example with Auricaps) but power supply should be done correctly but there is no real need for some extravaganza ...

http://i277.photobucket.com/albums/k...604/PassB1.jpg
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Old 28th March 2009, 01:04 PM   #1534
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Default b1-redux

nice comparison-interesting conclusion
thank-you
my thoughts when looking at your pics -are now upgrade the vol pots with the same battery vs simple regulation power supply and see if you can hear a difference.
thanks for your shared experience
rob
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Old 28th March 2009, 01:13 PM   #1535
Face is offline Face  United States
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I've tried Jantzen, Dayton, Sonic Caps, and Claritycaps in my B1, IMO the type of capacitor used can make an substantial difference.
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Old 28th March 2009, 01:20 PM   #1536
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Default Re: b1-redux

Quote:
Originally posted by rob lenk

now upgrade the vol pots with the same battery vs simple regulation power supply and see if you can hear a difference.
I don't see a pot at all in that pic - is one being used?

-j
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Old 28th March 2009, 02:00 PM   #1537
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Quote:
Originally posted by Face
I've tried Jantzen, Dayton, Sonic Caps, and Claritycaps in my B1, IMO the type of capacitor used can make an substantial difference.
Sure, what's your ranking?
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Old 28th March 2009, 02:14 PM   #1538
Salas is offline Salas  Greece
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I am still wondering why paying for quality capacitors when B1 can safely be made without input and output coupling if using symmetric (+/-) supplies. I still use it like that for months now, and the offset is practically null. And no cap always sounds better than any cap.
If I was using B1 for main system, I would use +/- 10V Mosfet shunts, and minimal applicable Shinkoh input and output series resistors (after test in given system for square waves). That is how making it for top performance.
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Old 28th March 2009, 11:51 PM   #1539
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Hi Salas,

Quote:
I am still wondering why paying for quality capacitors when B1 can safely be made without input and output coupling if using symmetric (+/-) supplies.
Avoiding crossover distortion and "coloring" the sound at our liking?

I've been told that some Tube amps do have capacitors on the signal path...

Anyway, I'll soon make that capacitor-less buffer for my TVC
I hope it is not too neutral...

Cheers,
M
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Old 29th March 2009, 12:04 AM   #1540
Salas is offline Salas  Greece
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Hi,

Its not cold when capacitor-less, it sounds neutral but soft. Maybe a bit ''gray''. The input and output resistors values and quality as well as the pot seal the tone. +/- 10V is the sweet spot I found for most relaxed sonics.
In tubes the capacitors are more to see because of the vacuum device one way nature, economic and bulk cost of extra PSUs etc. Every time we use better capacitors, they show there too. So it would be better if they weren't needed.
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