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Old 30th December 2008, 01:28 PM   #1031
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I was looking for DPDT switches. Some are On-Off-On and some are On-(On)-On. Which one with switch between two positions without being momentary or other.

Thanks,

Vince
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Old 30th December 2008, 01:35 PM   #1032
vonfilm is offline vonfilm  United States
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Thank you hayenc! Thank you Babowana! That makes it clear.

What do you think about my grounding the PCB to the two strips of copper tape in the bottom of the box below the PCB? I used bronze bolts through the corner holes with bronze washers and nuts to secure everything.

Could I use copper tape in the same manner to ground the rca jacks and dc jack? This would seem like Babowana did in his B1 with a metal plate to ground the rca jacks.
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Old 30th December 2008, 07:21 PM   #1033
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Has anyone experimented by placing a B1 before and after the volume pot?

There are many good reviews on the Burson Audio Buffer which is used by placing it between the source (eg CD player) and the preamp.
Apparrently this compensates for the ordinary opamp buffers found in most cd players.
The cheaper the cd player you have (assuming a direct relationship betwen price and quality of opamp buffer) the greater the potential benefit and audible difference you will experience.

"In conclusion, I would have to say that the Burson Audio Buffer reaps solid improvements in audio quality from mid-priced CD players, especially those with higher output impedance. Further up the price scale of CD playback where output stages may be of higher quality and impedances lower, the Burson influence becomes more subtle but still recognizable. Furthermore, potential improvements could be had from lowering the preamplifier's output impedance into the power amplifier by using the Burson as mediator between the two."
http://www.6moons.com/audioreviews/burson/buffer.html

There are heaps more positive reviews on this, just do a google on it.

So if anyone has already tried this (ie placing B1 before and after volume pot, or between their cd player and existing preamp), what were your listening impressions?

What would be the optimum input resistor in place of the pot?
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Old 31st December 2008, 08:01 AM   #1034
AndrewT is offline AndrewT  Scotland
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place the buffer in/at the output of any every source that you think may benefit.
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Old 2nd January 2009, 03:23 AM   #1035
rabbitz is offline rabbitz  Australia
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Quote:
Originally posted by thanh1973
Has anyone experimented by placing a B1 before and after the volume pot?

There are many good reviews on the Burson Audio Buffer which is used by placing it between the source (eg CD player) and the preamp.
Apparrently this compensates for the ordinary opamp buffers found in most cd players.
The cheaper the cd player you have (assuming a direct relationship betwen price and quality of opamp buffer) the greater the potential benefit and audible difference you will experience.

"In conclusion, I would have to say that the Burson Audio Buffer reaps solid improvements in audio quality from mid-priced CD players, especially those with higher output impedance. Further up the price scale of CD playback where output stages may be of higher quality and impedances lower, the Burson influence becomes more subtle but still recognizable. Furthermore, potential improvements could be had from lowering the preamplifier's output impedance into the power amplifier by using the Burson as mediator between the two."
http://www.6moons.com/audioreviews/burson/buffer.html

There are heaps more positive reviews on this, just do a google on it.

So if anyone has already tried this (ie placing B1 before and after volume pot, or between their cd player and existing preamp), what were your listening impressions?

What would be the optimum input resistor in place of the pot?
I've used both the B1 and the Burson Buffer which is a different beast. The B1 does not have the same effect as the Burson as the B1 output impedance is very high in comparison. I've also used the Burson modules after the pot for the basis of an active pre.

I think, but I don't know for sure, the B1 is only meant to help a passive pre by providing some buffering with a constant output impedance for the next stage. I think most sources would have a lower output impedance and would not benefit from a B1 on their output but I'm sure someone will correct me if I'm wrong.

I have to shutup and disappear now.
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Old 2nd January 2009, 09:00 PM   #1036
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This Burson buffer may be ok but it's specs are very obscure, as on the website he rightly goes on about careful matching between stages, yet the specs on the buffer are very sketchy.
No where does it say in his specs section it's
Input impedance
Output impedance
DC offset drift +-
(these could be all over the place)
Stick with the B1 you know what's going on with it. (safer for your poweramp)
These are some of the most important parameters when wanting to introduce a buffer into a system beside the sound.

Cheers George
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Old 2nd January 2009, 10:20 PM   #1037
Telstar is offline Telstar  Italy
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How easy would be to build the B1 within the power amp case, such as my F3? I'm going to put out the psu, so i'll have space. But I'm thinking about power and connections...

I dont like to have many boxes and cables around
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Old 2nd January 2009, 10:51 PM   #1038
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If you are concerned about the output impedance of the B1,
I suggest you try an output resistor value of your choice. The
intrinsic output impedance of that buffer is about 30 ohms, but
there would be some potential stability concerns using it
without some value of resistance, as it might oscillate into
capacitance.

If you have an oscilloscope, you can find out pretty easily.

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Old 2nd January 2009, 11:58 PM   #1039
Mihan is offline Mihan  New Zealand
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Default B1 Buffer vs Burson "Buffer"

As I understand it the main purpose of the unity (no) gain B1 Buffer is to take the place of the preamp in systems that don't need any extra gain to drive the power amp and to provide the correct impedance matching.

Too much gain can be a big problem in some systems and most CD players provide enough gain to drive most power amps.

Nelson Pass describes in his article on the B1, "A buffer is an active circuit using tubes or transistors, but has no voltage gain - it only interposes itself to make a low inpedance into a high impedance or vice versa."
The Burson "Buffer" I note has 6db of gain and is designed to be placed between source and preamp. This gain combined with the gain of the preamp would be too much for some systems.

My current pre amp has about 20db gain and I usually listen to the music at quite loud levels with the volume at 8 or 9 o'clock only 3 steps up from zero! One step can be too loud and the next lower step too soft. That is why I'm building a B1.
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Old 3rd January 2009, 02:39 AM   #1040
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Quote:
Originally posted by Mihan

My current pre amp has about 20db gain and I usually listen to the music at quite loud levels with the volume at 8 or 9 o'clock only 3 steps up from zero! One step can be too loud and the next lower step too soft. That is why I'm building a B1.

My speakers have low SPL of 84dB. So, I need a good power amp like F5. And, I find that B1 (0dB voltage gain) is good enough to replace my tube pre (headphone amp having high voltage gain). With B1 as an active pre, my home music sound level is loud enough and beautiful. In front of B1, I have a 6-source selector and two mono ladder type 47K attenuators for the left and right channels.

Using this system, I'm not listening to the music only, but also I'm listening to DVD movie sounds. When I watch DVD movies, however, I feel the sound level is somewhat low with B1 as a pre due to low output voltage from my DVD player, no, actually from my DAC. You know? For action movies, I love the wide sound of dynamics. For this reason, I insert my tube pre between B1 and F5. The tube pre has no source selector but has a 100K stereo volume pot.

Now, my current music system has the following chain:

CD/DVD players --> DAC --> two mono 47K ladder type pre volume attenuators(= L/R balancer) --> B1 --> 100K main volume pot --> active tube pre --> F5 --> 84dB speakers -->

I think this chain provides good and easy impedance matching at each stage. I adjust the pre volume and fix it for different music sources and turn the main volume knob up-and-down fully inbetween 6 to 6 o'clock.

Sound? Simply wonderful . . .

Happy New Year!!!

>><<


PS
I'm looking for B3 to replace the tube pre . . . Simple B3 . . .
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