[James Tanner]

What please is the Soft-Start circuit ("Micro Soft Start")? 

Hi Newbuyer,

With large power amplifiers with large transformers the power-up can draw 2-3 times the current it needs once it powers up. So we use 'softstart' circuits on the 4B and up to prevent circuit breakers from tripping during turn-on.

james

[NewBuyer]

Hi Newbuyer,

With large power amplifiers with large transformers the power-up can draw 2-3 times the current it needs once it powers up. So we use 'softstart' circuits on the 4B and up to prevent circuit breakers from tripping during turn-on.

james

Sounds like a very useful feature - thanks for your reply and explanation. 

[vegasdave]

7B SST-2
NEW POWER SWITCH AND MICRO SOFT START
INPUT RF FILTER
HIGHER INPUT IMPEDANCE
FULLY BALANCED - IN TO OUT
NEW OUTPUT CHOKES
NEW TRANSFORMER DESIGN
LOWER THD AND NOISE

No wonder those sounded so good @ CES!

[vegasdave]

These are probably stupid questions, but I'll ask anyway...

All power amps are SST-2?  I haven't seen any discussion about the 2B nor multi channel amps.

Am I correct in assuming the 2B-LP won't be an SST-2 (It never became an SST, right?)?

I saw you post something about a new external MM phono stage.  Any more info you can share?  Mainly will it need the external power supply, or will it have an internal one?

Hi Stu,

There are changes occurring in all the amplifiers - including the 2B SST. Most of the changes are the fully balanced (series) designs like the 7B and 14B. As you move down the line through the 4B,6B's,9B's, 3B's and 2B's there are less changes. Maybe I should post a list of each model and the changes made?

Yes we have re-introduced a less expensive phono stage (BP1/MPS1) which uses the older power supply from the BP25 series amplifiers. Phono is starting to make a real comeback and we wanted to offer a less expensive version than the BP1.5/MPS-2 combination. So the BP1 is 'MM' only but 'does include' the 'external' MPS1 power supply for $1,495 list as opposed to the BP1.5 (MM and MC)/MPS-2 which is $3800 list.

james

Does the new phono stage feature adjustable capacitance?

[James Tanner]

These are probably stupid questions, but I'll ask anyway...

All power amps are SST-2?  I haven't seen any discussion about the 2B nor multi channel amps.

Am I correct in assuming the 2B-LP won't be an SST-2 (It never became an SST, right?)?

I saw you post something about a new external MM phono stage.  Any more info you can share?  Mainly will it need the external power supply, or will it have an internal one?

Hi Stu,

There are changes occurring in all the amplifiers - including the 2B SST. Most of the changes are the fully balanced (series) designs like the 7B and 14B. As you move down the line through the 4B,6B's,9B's, 3B's and 2B's there are less changes. Maybe I should post a list of each model and the changes made?

Yes we have re-introduced a less expensive phono stage (BP1/MPS1) which uses the older power supply from the BP25 series amplifiers. Phono is starting to make a real comeback and we wanted to offer a less expensive version than the BP1.5/MPS-2 combination. So the BP1 is 'MM' only but 'does include' the 'external' MPS1 power supply for $1,495 list as opposed to the BP1.5 (MM and MC)/MPS-2 which is $3800 list.

james

Does the new phono stage feature adjustable capacitance?

I will check on that Dave - I believe it does.

james

[95Dyna]

James,

I noticed three items new on the 14B that were not listed for the 7B: reduced wiring, new chassis design and new power supply PCB.  Is there any significance to these items in terms of performance that would favor the 14B over the 7B relative to the "ideal power curve" design objectives.

Thanks,

Bill

Hi Bill,

No -the 7B being a mono amp had less wiring and did not need the PCB change given that its a mono amp. The 7B has 2 advanatges over the 14B. 1. Mono --so you can place it close to the speaker and use very short speaker cables and 2. It has double the storage capacitance of the 14B.

james

Thanks James.  To your two 7B advantages I would add a third for us guys in our late 50's.  It's easier to pick up 50 lbs. twice than 85 lbs. once!   

[predrag]

@95dyna

Well, as a happy owner of a pair of 7B SST2 from the first hand I can tell you that even as mono´s they are no lightweights at all!
As you can see in my avatar to put them softly in bottom shelves of my rack it takes two pairs of hands anyway.
I was away on a business trip for a week and meanwhile borrowed them to my friend who has monoblocks from another manufacturer and he was blown away by 7B´s performance!  He tried them on PMC EB1 (like mines) and Audio Physic Virgo.
Next week he will borrow me his Quad´s 2905 speakers. They are collecting dust unboxed in his back room.
I am really curious about them!

[95Dyna]

Hi predrag,

Not to change the subject of the thread but I would love to know how your friend regards the Virgos vs the EB1's.  I've developed an interest in the Scorpio II, Virgo V and Avanti V.  Since it would be impossible for me to actually compare them to the EB1, PB1 or IB2 using the 7Bs, perhaps you could shed some light on the question regarding the general differences between the two product lines.

Thank you,

Bill

[95Dyna]

Hi James,

You mentioned the 7B has twice the storage (power supply?) capacitance as the 14B.  Can you tell us what the capacitance is of the 7B and and some detail on what advantage this provides the 7B over the 14B.  I don't see this spec listed in the technical section of the website.

Thanks,

Bill

[James Tanner]

Hi James,

You mentioned the 7B has twice the storage (power supply?) capacitance as the 14B.  Can you tell us what the capacitance is of the 7B and and some detail on what advantage this provides the 7B over the 14B.  I don't see this spec listed in the technical section of the website.

Thanks,

Bill

Hi Bill,

The 7B has 160,000 uf per channel (mono amp) and the 14B has 88,000 uf per channel (stereo amp).

The advantage of more storage is at very high power demand it can supply more current to the load.

james

[95Dyna]

Thanks James.  I know Bryston doesn't like to engage in marketing "gamesmanship" but that spec on the 7B is exceptional.  I was reading of another amp by a famous US manufacturer that highlighted their 300K uF total for both channels of the stereo amp as being one of its biggest selling points.  Don't be shy when you have an outstanding spec to publish!

Bill

[Sasha]

Hi predrag,

Not to change the subject of the thread but I would love to know how your friend regards the Virgos vs the EB1's.  I've developed an interest in the Scorpio II, Virgo V and Avanti V.  Since it would be impossible for me to actually compare them to the EB1, PB1 or IB2 using the 7Bs, perhaps you could shed some light on the question regarding the general differences between the two product lines.

Thank you,

Bill

Maybe I can jump in, I listened extensively to EB1i and latest Scorpio, to some lesser extent to Virgo.
It was not side by side comparison, but was long and frequent enough to allow me to draw reasonable conclusions.
Main points would be that Audio Physic speakers have very good midrange which I would dare to say matches or surpasses EB1i but not IB2 and higher models in PMC line-up, while the bass performance is disappointing in Audio Physic (not lack of bass, but lack of definition), especially when comparing to bass performance of EB1i which IMO surpasses that of IB2 and MB2.
It would seem that smaller Audio Physic speakers are less problematic in bass.
Note that I am talking in more or less absolute terms, for example it does not imply that Audio Physic bass is bad, just that it was not among the best, same as midrange on EB1i, not bad but not something to write home about either.

[95Dyna]

SST2 (SQUARED) MODEL CHANGES JAN 2009


The SST squared has a number of changes but most of the changes involve the 'Fully Balanced' amps like the 7B's and the 14B's. The 14B's and the 7B's are essentially new amplifiers!
 
The main design concept change in the Squared Series is:
A significant part of the design criteria for the SST2 was to develop amplifiers that would maintain an ideal power curve through the 'first and last watt'. Most amplifiers exhibit a power curve whereby the best noise floor, drive capability and distortion are maintained from about 1/3 power and up. The new Bryston SST2 (squared) series maintain their ideal power curve right from the first watt to the last watt.

Think of it like a torque curve in a car. The sweet spot or the torque curve has been expanded.


SST2 (SQUARED) MODEL CHANGES JAN 2009

2B SST-2
NEW POWER SWITCH
INPUT RF FILTER
HIGHER INPUT IMPEDANCE
FULLY BALANCED IN BRIDGED MODE
LOWER THD AND NOISE

3B SST-2
NEW POWER SWITCH AND MICRO SOFT START
INPUT RF FILTER
HIGHER INPUT IMPEDANCE
FULLY BALANCED IN BRIDGED MODE
LOWER THD AND NOISE

4B SST-2
NEW POWER SWITCH AND MICRO SOFT START
INPUT RF FILTER
HIGHER INPUT IMPEDANCE
FULLY BALANCED IN BRIDGED MODE
LOWER THD AND NOISE

6B SST-2
NEW POWER SWITCH AND MICRO SOFT START
INPUT RF FILTER
HIGHER INPUT IMPEDANCE
LOWER THD AND NOISE

7B SST-2
NEW POWER SWITCH AND MICRO SOFT START
INPUT RF FILTER
HIGHER INPUT IMPEDANCE
FULLY BALANCED - IN TO OUT
NEW OUTPUT CHOKES
NEW TRANSFORMER DESIGN
LOWER THD AND NOISE

9B SST-2
NEW POWER SWITCH AND MICRO SOFT START
INPUT RF FILTER
HIGHER INPUT IMPEDANCE
LOWER THD AND NOISE

14B SST-2
NEW POWER SWITCH AND MICRO SOFT START
INPUT RF FILTER
HIGHER INPUT IMPEDANCE
FULLY BALANCED - IN TO OUT
NEW POWER SUPPLY PCB
NEW CHASSIS
NEW TRANSFORMER DESIGN
REDUCED WIRING
NEW OUTPUT CHOKES
LOWER THD AND NOISE

James,

What's the new input impedence spec for balanced and single ended on the 7B?

Bill

[James Tanner]

Input Impedance:

2B, 3B, 4B, 6B, 9B - 50k Ohms single ended, 40k Ohms balanced

7B, 14B, 28B - 15k Ohms single ended, 20k Ohms balanced

james

[FM Acoustics]

James, as the 7B can be ordered wired in Series or Parallel (for driving loads under 4 Ohms), could you please share how the two versions compare to each other? Would like to see the W/V/Amperes specifications for each version....

Another thing I noticed is that while the 7B has double the storage capacitance of the 14B, I see that the 14B has double the slew rate of the 7B, 120V/µs vs 60V/µs. Do you see any benefit for the higher slew rate on the 14B?

Thanks

[James Tanner]

James, as the 7B can be ordered wired in Series or Parallel (for driving loads under 4 Ohms), could you please share how the two versions compare to each other? Would like to see the W/V/Amperes specifications for each version....

Another thing I noticed is that while the 7B has double the storage capacitance of the 14B, I see that the 14B has double the slew rate of the 7B, 120V/µs vs 60V/µs. Do you see any benefit for the higher slew rate on the 14B?

Thanks

Hi FM,

We rarely sell the 'parallel' version of the 7B any longer - in fact I can not remember the last time we did. The 7B parallel is really only required with speakers in the 1-2 ohm area and that is a rare occurrence.  The reason for the parallel vs series modes is that as the impedance of a speaker goes down it generally requires more current and less voltage. So it is a balancing act between voltage and current.  At 8 ohms for instance the 'series' 7B will give you about 600 watts while the 7B in 'parallel' would give you about 180 watts at 8 ohms.  At 2 ohms the reverse would happen. So you can see it is a balancing act as to which is the better option given a specific speaker load.

Loudspeakers are complex loads and at any given frequency they are asking for voltage or current depending on the frequency etc. In fact we have found that the ability of an amplifiers output stage to respond instantaneously to voltage or current requirements at any given frequency is much more important than whether it provides high current or high voltage at one extreme or the other.

I think the 60 volts on the 7B may be a miss quote - where did you see that and I will check. Slew rate is an indication of the speed a circuit is capable of but as you suggest it is one of many areas that have to be taken into account when designing a good amplifier.  The research I have seen indicates that anything over 25 volts per microsecond is a mute point.

james

[95Dyna]

James, as the 7B can be ordered wired in Series or Parallel (for driving loads under 4 Ohms), could you please share how the two versions compare to each other? Would like to see the W/V/Amperes specifications for each version....

Another thing I noticed is that while the 7B has double the storage capacitance of the 14B, I see that the 14B has double the slew rate of the 7B, 120V/µs vs 60V/µs. Do you see any benefit for the higher slew rate on the 14B?

Thanks

Hi FM,

I'm pretty certain the 14B slew rate spec is total for both channels of the amp.  Just multiply the 7B by 2 for apple to apples and the two are equal in a two channel operation.

Bill

[FM Acoustics]

Hi James,

Your explanation is exactly how I thought the things worked. Right now I don't have the possibility to order a pair of 7B SST2, but I plan to do it when funds will allow. The basic idea is that when ordering it you have to match it to the speakers. An efficient speaker with a low impedance load would be better served by the Parallel version; likewise, inefficient speakers with a load above 4 Ohms would be better served by an amplifier which is able to deliver higher voltage swings than current, so the Series model would be better suited.

I mainly asked because I was struck by the opposite design philosophy which Bryston and Accuphase seem to have. Bryston prefers the voltage camp, while Accuphase the current camp. For example, the Accuphase largest mono amp has a 3kVA transformer and it delivers only 250W into 8 Ohm, but this relative low power rating is compensated by the ability to deliver current and "double down" its power so that it's able to give 2000W at 1 Ohm.

Regarding the slew rate, I've read it on the specs link besides each SST model that opens in a small window with the specifications list. The 14BSST has listed 120V/µs and the 7BSST 60V/µs.

http://bryston.com/BrystonSite05/BrystonDocs.html

Bill, I don't know if this is so, because the other stereo models are also 60V/µs.

[vegasdave]

These are probably stupid questions, but I'll ask anyway...

All power amps are SST-2?  I haven't seen any discussion about the 2B nor multi channel amps.

Am I correct in assuming the 2B-LP won't be an SST-2 (It never became an SST, right?)?

I saw you post something about a new external MM phono stage.  Any more info you can share?  Mainly will it need the external power supply, or will it have an internal one?

Hi Stu,

There are changes occurring in all the amplifiers - including the 2B SST. Most of the changes are the fully balanced (series) designs like the 7B and 14B. As you move down the line through the 4B,6B's,9B's, 3B's and 2B's there are less changes. Maybe I should post a list of each model and the changes made?

Yes we have re-introduced a less expensive phono stage (BP1/MPS1) which uses the older power supply from the BP25 series amplifiers. Phono is starting to make a real comeback and we wanted to offer a less expensive version than the BP1.5/MPS-2 combination. So the BP1 is 'MM' only but 'does include' the 'external' MPS1 power supply for $1,495 list as opposed to the BP1.5 (MM and MC)/MPS-2 which is $3800 list.

james

Does the new phono stage feature adjustable capacitance?

I will check on that Dave - I believe it does.

james

So what did you find out, James...

[James Tanner]

HI Dave,

Yes it does.

james