[guest1121]

I purchased a 4BSST and 9BSST in about 2002, and even though my pre/pro has balanced outputs, I've never used them in conjunction with my Bryston amps.

Can someone tell me if my amps are fully balanced internally?  I've heard that recent Bryston amps are, but I'm not sure how I go about determining if mine are.  What advantage would a fully balanced unit provide?

Maybe James or someone else can help?

TIA,

Scott

[Bob Reynolds]

I believe that Bryston's amps are not "fully balanced". You can find an article about this in one of their past newsletters on their web site. The term seems to be somewhat misleading and misunderstood.

The major advantage of having proper balanced connections is that the differential input will cancel (by subtraction) common mode noise (i.e., noise that is common to both the + (pos) and - (neg) signal conductors) that has been picked up by the interconnect cable. You can look at the schematic for your amp (on the Bryston web site) and see that it has a proper differential input.

My limited understanding is that it is possible to configure a differential input that maintains a balanced signal on its output. I believe each such subsequent gain stage will also cancel common mode noise that has been picked up since the previous gain stage. To maintain a balanced signal throughout the circuit requires at least twice the parts count. Also, the parts have to match to very close tolerances or the CMRR will not be very good.
For those more technical, please correct me where ever I have misspoke.

[James Tanner]

I purchased a 4BSST and 9BSST in about 2002, and even though my pre/pro has balanced outputs, I've never used them in conjunction with my Bryston amps.

Can someone tell me if my amps are fully balanced internally?  I've heard that recent Bryston amps are, but I'm not sure how I go about determining if mine are.  What advantage would a fully balanced unit provide?

Maybe James or someone else can help?

TIA,

Scott

HI Scott,


The 7B SST, 14B SST and 28B SST are 'fully balanced' throughout as each channel is a series designed amplifier. All Bryston amplifiers have fully balanced differential inputs.

james

[Bob Reynolds]

I purchased a 4BSST and 9BSST in about 2002, and even though my pre/pro has balanced outputs, I've never used them in conjunction with my Bryston amps.

Can someone tell me if my amps are fully balanced internally?  I've heard that recent Bryston amps are, but I'm not sure how I go about determining if mine are.  What advantage would a fully balanced unit provide?

Maybe James or someone else can help?

TIA,

Scott

HI Scott,


The 7B SST, 14B SST and 28B SST are 'fully balanced' throughout as each channel is a series designed amplifier. All Bryston amplifiers have fully balanced differential inputs.

james

From the schematic of the 28B, it does look like it is fully balanced.

From the schematic of the 14B, the output of the differential input looks to be single ended. It looks like that SE signal is run through an inverter which later becomes the - (neg) part of a balanced output.

The schematic for the 7B & 4B are combined so it's confusing, but the output of the differential input appears to be single ended. I'm not sure what happens after that.

So I stand corrected on my previous statement that Bryston's amps are not fully balanced. As James stated, some are. I would like to see a separate schematic for the 7B SST, since that's what I own.

James, thank you for clearing that up for me and I hope I haven't stepped on any toes. Please let me know when I'm out of line. I really appreciate that Bryston publishes the schematics so that anyone can check things out for themselves.

All the best,
Bob

[guest1121]

Thanks for the responses, Bob & James.  So, if I understand your responses correctly, the following statements are true:

1. My 4B SST and 9B SST are not fully internally balanced
2. The 4B SST and 9B SST (along with all Bryston amps) have fully balanced differential inputs.

If both of these statements are true, is it fair for me to assume that by using balanced cables as opposed to RCA composite interconnects, I will achieve less noise?  Will this be noticeable?  Does it equate to a higher signal-to-noise ratio?

I'm trying to decide if it's worth using balanced cables in my setup...hence, all of these questions.  If the difference is inaudible, I won't bother, but if there's a chance at a performnance improvement, I'm all over it.  If it matters, my pre/pro right now is a Lexicon MC-12B.

Thanks,

Scott

[James Tanner]

Thanks for the responses, Bob & James.  So, if I understand your responses correctly, the following statements are true:

1. My 4B SST and 9B SST are not fully internally balanced
2. The 4B SST and 9B SST (along with all Bryston amps) have fully balanced differential inputs.

If both of these statements are true, is it fair for me to assume that by using balanced cables as opposed to RCA composite interconnects, I will achieve less noise?  Will this be noticeable?  Does it equate to a higher signal-to-noise ratio?

I'm trying to decide if it's worth using balanced cables in my setup...hence, all of these questions.  If the difference is inaudible, I won't bother, but if there's a chance at a performnance improvement, I'm all over it.  If it matters, my pre/pro right now is a Lexicon MC-12B.

Thanks,

Scott

Hi Scott,

Like most things in life there is a plus/minus to using Balanced circuits.

Using a Balanced line will not lower the 'inherent' noise floor of your system - it will just reduce or eliminate any outside added noise from affecting your system. Balanced circuits reject outside noise and interference through a method called 'common mode rejection'.

There are different types of Balanced circuits - Transformers, IC's and Discrete. We use Discrete Class A circuits for all our differential balanced systems. 

With a Balanced circuit you have to have a 'sending' and a 'receiving' circuit so you are adding two more amplification circuits to your system using Balanced XLR's as opposed to the single ended RCA. So from a purist point of view you could argue that Balanced circuits are adding circuitry and therefor compromising the purity of the signal path. You have to be careful though when comparing Balanced Lines to RCA single ended lines because Balanced circuits usually add 6dB of gain so the louder sound always sounds better.

Anyway, I have found that given the amount of RF and other electronic interference that permeates our lives this days running properly designed differential balanced lines does more good than harm.

james

[Bob Reynolds]

I'm a big fan of balanced lines, but whether you'll notice an audible improvement I think will be determined by how noisy an environment your system is in. When I switched to balanced lines I think I noticed an increase in "air" around instruments. But, at that time I was not aware of the importance of matching levels to make valid comparisons, so as James stated it may have been a level difference that I was hearing. Regardless, I much perfer the XLR connector over RCA and I'm convinced of the theoretical benefits of balanced lines.

[rob80b]

Hi Scott,

Like most things in life there is a plus/minus to using Balanced circuits.

Using a Balanced line will not lower the 'inherent' noise floor of your system - it will just reduce or eliminate any outside added noise from affecting your system. Balanced circuits reject outside noise and interference through a method called 'common mode rejection'.


james

For what it’s worth, I started using a balanced interconnect a few months ago between the BP25 and the 3BST. I did not notice any obvious improvements sound wise.
What did come to my attention though was the elimination of any noise coming through the ac lines, one example was a ceiling fan in another room that always produced an unnerving pop though the speakers when ever it was turned on and off, using balanced interconnects that has been totally eliminated, a definite plus.

Robert

[guest1121]

Guys,

Thanks so much for the replies; I now feel as though I understand this issue much better.  What I might do is borrow a set of balanced cables, re-balance the channels, and see if I like the way it sounds.  If not, I can always go back to RCA interconnects.

Thanks for helping me along!

Scott

[Daniel Datchev]

Hi James,
recently I come across article about Yamaha A-S2000 integrated Amplifier
where it was described as the first full balanced amplifier, not mentioning other
manufacturers like Bryston who implement already these type of approach.
Do have a chance to hear them?
As similar approach you have in 7B,14B and 28B I again will ask you a question
you `ve been already asked. Do you think or have the company intention to
implement such a topology  in lower order products?
Daniel

[James Tanner]

Hi James,
recently I come across article about Yamaha A-S2000 integrated Amplifier
where it was described as the first full balanced amplifier, not mentioning other
manufacturers like Bryston who implement already these type of approach.
Do have a chance to hear them?
As similar approach you have in 7B,14B and 28B I again will ask you a question
you `ve been already asked. Do you think or have the company intention to
implement such a topology  in lower order products?
Daniel

Hi Daniel,

Fully Balanced as used by some refers to the fact that the plus side of the waveform and the negative side of the waveform have independent circuit paths throughout the component. We do this on the 28B's the 7B's and the 14B's because they are 'series' designed amplfiers.  The 9B,6B,4B 3B and 2B are not series designs so we do not use independent circuit paths for them.  We use fully differential balanced inputs on all our amplifiers to reduce noise at the input if using a balanced system.

The so called fully balanced topology in the larger amps has much more to do with the 'series' design philosophy rather than any particular performance advantage.

james