[flom]

Hi everybody,
I followed the operating guide http://www.bryston.ca/BrystonSite05/pdfs/SSTAmplifiers/6...(RP8)PMC.pdf in order to bridge my 9BSST to better drive my 2 revel F30. The result is great !
Nevertheless, I am wondering if this configuration is compliant with bi-wiring ?
The guide indicates A ground wire (16g or heavier wire recommended) must be connected between the two BLACK output terminals on the 6B amplifier channels being bridged. DO NOT CONNECT ANYTHING ELSE TO EITHER OF THESE BLACK OUTPUT TERMINALS!

Can I connect my speakers using bi-wiring ? What about 16g please ?

Last question : Are the capacities added (from 150000 to 30000 now ?) and what about power at 4ohms (300w@8ohms specified)

Thanks for your help
With best regards
Fabien

[brucek]

Can I connect my speakers using bi-wiring ?

Yes, there is essentially no electrical difference between bi-wiring and regular wiring of a speaker (which is the reason for its dubious advantage).
You still use the same two positive red terminals on the rear of the 9BST for each speaker, but you will supply two pairs of speaker cable from each set of red terminals as opposed to a single pair. Remember that the positive red terminal on the 9B is the one with the phase switch set to zero and the negative is the one with the phase switch set to 180.

What about 16g please ?

This is simple the thickness of the wire used. It means 16 gauge. The higher the number, the thinner the wire. Best to use the same gauge as your speaker wire (i.e. 12 gauge).

brucek

[jethro]

Fabien:

If you can bi-wire your speakers then I think you would be better off
bi-amping rather than bridging or bi-wiring since you are already using
4 channels. If you haven't bi-amped before then be very careful
and ask for help. Make sure that you remove the speaker terminal
bridges if you try to bi-amp. I'm not sure of the exact terminology, but bridging
makes it more difficult for the amp to handle lower impedances which
may or may not be a problem with your speakers.

HTH, Steve

[brucek]

If you can bi-wire your speakers then I think you would be better off
bi-amping rather than bridging or bi-wiring since you are already using
4 channels.

Completely agree - much better solution..

[flom]

Brucek, Steve, thanks for your help and quick feedback.

I did all the tests this afternoon.
Previously I had the occasion to test biamp vs biwiring. Biamp was better but the impact is the usage of 2 channels. I had a discussion with Chris Russel some weeks before http://www.audiocircle.com/index.php?topic=32979.msg293062#msg293062

After that previous experience I decided to stay in a biwiring configuration until I saw the bridging option.
This week I tested it as recommended in the documentation. The sonic / audio difference was huge (largest bandwith / more respected tones / bass better mastered...). That 's why I wanted to add to bridging the possibility of biwiring.
Today, at the time Brucek pointed the way to do this, I understood that I just had not to use black connectors on the 9B 
I did it so and tested it. The biwiring on a bridged configuration was altering the resolution and a lot of bad effects were audible...
I tested again the normal biwring and the passive bi-amp again. Both of these customizing are not at the level of results I gain from the normal bridged config, as mentionned in the Bryston doco...
All my tests were done at low, then high volume (till 108 db) & even if it is theorically more difficult for the amp to handle lower impedances I perceived nothing w/ my F30. But it could be an other issue...

Thanks again to both of you. I will stay in this config this week & will give you a return with more feedback

Cheers

Fabien

[jethro]

Fabien:

I see where you are going with your setup now. Chris Russell's revelation that
passive bi-amping doesn't really provide more power to each driver was an
eye-opener. I'm not an electrical engineer so I have been going by what I have read
elsewhere. It's nice how Chris succinctly states his replies so the layman can understand.

I always thought that bridging an amplifier was harmful to the sound quality.
If Chris/James are listening - is this another false impression that I have ?

Thanks, Steve

[brucek]

Chris Russell's revelation that passive bi-amping doesn't really provide more power to each driver was an eye-opener.

I think you have to put into context what he was saying in that statement, which was,"a passive biamped setup actually provides almost the exact same power overall per driver, since both amps receive the full spectrum of music.". This only makes sense. The same frequency dependant signal is still across each driver in the speaker and so consumes the same power.
So, certainly you won't be able to play the system any louder, or avoid clipping any differently, but, the difference in a passive bi-amp situation is that the total current drawn from each individual amplifier will be less. The current drawn from each amp now becomes frequency dependant, and as such the power required from the power supply is reduced. In an amplifier that shares a common supply, this then is a zero sum game. But in an amplifier such as the 9BST which uses independant supplies in each module, I can see a bonus.

I always thought that bridging an amplifier was harmful to the sound quality.
If Chris/James are listening - is this another false impression that I have ?

Not if it's done well. Check the THD and intermod specs of any Bryston amp in bridge mode and you'll see about the same figures as non-bridge. It's a good idea to check that spec in an amp, because many amps are quite poor in bridge. The amp will run hotter though, since each output channel will see half the load impedance. So if you hook up an 8 ohm speaker to a bridged output, each channel will see 4 ohms. Hook up a 4 ohm speaker and it will see 2 ohms. That's a lot of extra current and the amp will run hotter.

brucek

[Joshua]

What is the power you get at 8 ohms from each channel after bridging the 9B SST (five channel version).

[flom]

What is the power you get at 8 ohms from each channel after bridging the 9B SST (five channel version).

The documentation specifies 300w for the 2 bridged channels. Therefore 2*300w + 1*140 (the 5th non bridged one)
Fabien

[BMU (Bryston Maggie User)]

Interesting discussion...

I have a Maggie 1.6 QR's passively bi-amped with 4/5 channels of my 9B-ST.

I've never tried just using a single 9B-ST channel - which I understand is essentially equivalent to a 3B-ST.

Reading this thread I'm curious about the potential benefits of using 4/5 channels in a bridged configuration.  More power the better for Maggies as they say...

Of course I would have to upgrade my 9BST to SST status.  But as I understand it the factory upgrade does NOT include a back panel change.

James, any possibility of offering an upgrade path with a back panel change to allow bridging of adjacent channels?


Thanks
Alex

[BMU (Bryston Maggie User)]

I should add my previous experience with older Paradigm Studio 60's...

Basically there was a very notable difference when I went from single amping with 1 9BST channel to passively biamping with 2 9BST channels per speaker.  Easily discernable improvements in clarity and better bass control.  As I've posted above I didn't even bother with single amping my Maggies when I got them.

Alex

[James Tanner]

Interesting discussion...

I have a Maggie 1.6 QR's passively bi-amped with 4/5 channels of my 9B-ST.

I've never tried just using a single 9B-ST channel - which I understand is essentially equivalent to a 3B-ST.

Reading this thread I'm curious about the potential benefits of using 4/5 channels in a bridged configuration.  More power the better for Maggies as they say...

Of course I would have to upgrade my 9BST to SST status.  But as I understand it the factory upgrade does NOT include a back panel change.

James, any possibility of offering an upgrade path with a back panel change to allow bridging of adjacent channels?


Thanks
Alex

Hi Alex,

There are no plans for a modified back panel on the 9B SST but there are special cables we build to allow you to bridge 2 of the 9B channels. We do not recommend the bridged mode into less than 8 ohms or a very easy 'duty cycle'.

james

[BMU (Bryston Maggie User)]

Hi Alex,

There are no plans for a modified back panel on the 9B SST but there are special cables we build to allow you to bridge 2 of the 9B channels. We do not recommend the bridged mode into less than 8 ohms or a very easy 'duty cycle'.

james


[/quote]

So James, you're not recommending the bridged mode operation of my 9BST for my 4 ohm Maggies?   


Maybe its my misconception but I thought bridging would provide more power to drive "difficult loads" at the expense of using 2 channels and possibly more distortion (depending on the design).   

Alex

[James Tanner]

Hi Alex,

When you use an amplifier in Bridged mode the impedance it "see's" is 1/2. So a 4 ohm load - like the Maggies - becomes 2 ohms. At 2 ohms the load is asking for double the current it needs at 4 ohms.

The concern is that the amplifier in trying to deliver that amount of current would overheat and the thermal protection would shut the amp down.

james