Bryston Cubed amp owners please check in ...
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Mr Peabody
Well-known member
I noticed the Cubed amps recently and wondered how they sound. Prices seem pretty good for a name brand muscle amp. Also, they have two models within $200 of each other I was wondering what the difference was. The sight I was looking at was giving me issues, I need to try again.
Jack
Well-known member
They carry them at AA so you can try them for the cost of return shipping if you have to give up on the ML. Do the JBL's need that much juice? Another amp you might want to try out is the BHK 250.
Mr Peabody
Well-known member
I wouldn't need 300x2 necessarily but I like to have reserve. The 4367's are 94dB but do seem to like current.
The Cubed amps don't double down, the design with the convection cooling etc. sounds a bit similar to my 532h or Crown. Cubed are dual mono though with separate power supplies. Bottomline is how the ears like it when it's playing though.
The Cubed amps don't double down, the design with the convection cooling etc. sounds a bit similar to my 532h or Crown. Cubed are dual mono though with separate power supplies. Bottomline is how the ears like it when it's playing though.
Jack
Well-known member
I haven't heard one in years so don't really know how they sound. Joe liked the last version and now they have the new 2.5 which might be enough power if those are your endgame speakers. The BHK does double down and mine is staying put for a while. You can fine tune it a bit with the input tubes so might be worth a listen.
- Thread Author
- #6
Yes, I absolutely loved the 28BSST2 amps and only sold them to get the 28 Cubed. Shipping dates were unknown at the time and I kinda got sidetracked. I still think about them but am curious what others think about them after living with them for a while. Having a little extra headroom is always welcome. My 28 squared were smooth and slightly sweet with no grain. I expect no less and actually more of the good stuff from the new Cubed amps. IMO, a great SS pre or a nice tube preamp could be a killer combo. Certainly not your typical solid state amps.
Joe - I had the little 3BSST3 in the store on the Magico M3's last month. WOW!! I honestly wasn't expecting what I heard. Tight bass. Sweet top end. I kept standing over it saying "where the hell is all that power coming from?"
Not the new SST3, but I've owned the 9BSST2 FOREVER. No wonder there is a 20 year warranty. It's built like a tank.
Sent from my iPhone using Tapatalk
Not the new SST3, but I've owned the 9BSST2 FOREVER. No wonder there is a 20 year warranty. It's built like a tank.
Sent from my iPhone using Tapatalk
James Tanner - Bryston
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Thanks Mike - coming from you this is high praise indeed - will pass it along - thanks.
james
james
James - does Bryston have a new SSP coming out?
James Tanner - Bryston
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Hi Mike
No plans on that front currently - the SP3 is still selling well.
james
No plans on that front currently - the SP3 is still selling well.
james
Mr Peabody
Well-known member
The Bryston website has some basic info on the Cubed amps, some design features but really don't tell much about them. Anyone know if a white paper or more indepth description is available? Example, are they differentially balanced or XLR inputs just that, type of output devices and amount, etc.
James Tanner - Bryston
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Hi Mr Peabody
Will post some for you.
BRYSTON
Bryston has used Class AB output stage architecture for many years because it provides an excellent platform for one of the things we find most important in music reproduction: Linearity. There are numerous ways to implement a high-current output stage for an amplifier meant to drive speakers. There is Class A where all output devices carry signal current at all times; Class B where the individual output devices carry signal current 50% of the time, each on one polarity of the signal; class AB where each polarity of output device carries signal current more than 50%, but less than 100% of the waveform cycle.
There is also Class D, where the signal is converted to a varying pulse-width square-wave on a supersonic carrier, but that is beyond the scope of these comments. Suffice it to say that this can be a good, accurate way to amplify a signal, but the overall linearity is dependent on the accuracy of the conversion to an HF carrier, modulated square-wave. It also presents challenges with excluding the carrier itself from the final, delivered signal to the speakers. It can represent many hundreds of watts of RF energy, and the necessary filtering has a tendency to affect audio frequencies to some extent.
Once we have chosen maximum linearity as one of the most important parameters of an output stage, we can look at the characteristics of the power devices to see where they perform best, and where they may have problems. Power transistors have a rather broad linear region in their transfer function, from just above their 'on' threshold, up to the higher current region closer to saturation, or fully 'on'. At very low current near threshold, and at very high current near saturation, the transfer function bends toward an overall 'S' shape. Thus, it becomes obvious that for the best linearity we want to keep the output devices operating within the optimal linear region of their transfer function. We can do that by operating the output transistors as opposite polarity pairs, switching from one polarity to the other at the zero-crossing region. Class B will inevitably show a discontinuity in the zero-crossing region, since as we saw above, the transistors are not linear at those low-Voltage, low current parts of the signal. Placing a known continuous biasing current on the transistors prevents them from entering that nonlinear part of their curve, and smoothes the zero-crossing region. There may still be a small discontinuity in the zero-crossing region if the upper and lower output devices do not have exactly equal and opposite characteristics at the crossover point. Unfortunately, opposite polarity devices have similar, but not exactly equal, characteristics.
Attempting to overcome the small remaining zero-crossing discontinuity by increasing the bias current to a level that it keeps the output devices 'on' for 100% of the waveform cycle does nothing but push the devices into the nonlinear region at the high-current end of their transfer function. Distortion actually goes up, not down, all else being equivalent.
Thus, Bryston began exploring the possibility of giving the two polarities of output transistor exactly 'equal and opposite' characteristics. In that way the zero-crossing region can remain linear. The way we found was to incorporate our 'Quad Complementary' output section, discussed in the white paper sent to you by James Tanner earlier. That output configuration goes a long way toward virtually eliminating zero-crossing artifacts from the signal, and sound quality is very improved.
In the future, it remains to be seen whether Class D can achieve the overall musicality that a correctly designed Class AB amplifier can achieve. It is not there yet, but we feel it holds promise.
In today's noisy world, there are challenges remaining in terms of an amplifier's immunity to RF and other noise signals coming in on the power-supplies and input cables. Our latest 'Cubed' models have demonstrated that it is quite important to take that into account as well as overall linearity of a test signal. That's also outside of this discussion, of course, but it matters.
I hope this above is helpful, but please let me know if you have questions or comments.
Best regards,
Chris Russell
Bryston Ltd.
Will post some for you.
BRYSTON
Bryston has used Class AB output stage architecture for many years because it provides an excellent platform for one of the things we find most important in music reproduction: Linearity. There are numerous ways to implement a high-current output stage for an amplifier meant to drive speakers. There is Class A where all output devices carry signal current at all times; Class B where the individual output devices carry signal current 50% of the time, each on one polarity of the signal; class AB where each polarity of output device carries signal current more than 50%, but less than 100% of the waveform cycle.
There is also Class D, where the signal is converted to a varying pulse-width square-wave on a supersonic carrier, but that is beyond the scope of these comments. Suffice it to say that this can be a good, accurate way to amplify a signal, but the overall linearity is dependent on the accuracy of the conversion to an HF carrier, modulated square-wave. It also presents challenges with excluding the carrier itself from the final, delivered signal to the speakers. It can represent many hundreds of watts of RF energy, and the necessary filtering has a tendency to affect audio frequencies to some extent.
Once we have chosen maximum linearity as one of the most important parameters of an output stage, we can look at the characteristics of the power devices to see where they perform best, and where they may have problems. Power transistors have a rather broad linear region in their transfer function, from just above their 'on' threshold, up to the higher current region closer to saturation, or fully 'on'. At very low current near threshold, and at very high current near saturation, the transfer function bends toward an overall 'S' shape. Thus, it becomes obvious that for the best linearity we want to keep the output devices operating within the optimal linear region of their transfer function. We can do that by operating the output transistors as opposite polarity pairs, switching from one polarity to the other at the zero-crossing region. Class B will inevitably show a discontinuity in the zero-crossing region, since as we saw above, the transistors are not linear at those low-Voltage, low current parts of the signal. Placing a known continuous biasing current on the transistors prevents them from entering that nonlinear part of their curve, and smoothes the zero-crossing region. There may still be a small discontinuity in the zero-crossing region if the upper and lower output devices do not have exactly equal and opposite characteristics at the crossover point. Unfortunately, opposite polarity devices have similar, but not exactly equal, characteristics.
Attempting to overcome the small remaining zero-crossing discontinuity by increasing the bias current to a level that it keeps the output devices 'on' for 100% of the waveform cycle does nothing but push the devices into the nonlinear region at the high-current end of their transfer function. Distortion actually goes up, not down, all else being equivalent.
Thus, Bryston began exploring the possibility of giving the two polarities of output transistor exactly 'equal and opposite' characteristics. In that way the zero-crossing region can remain linear. The way we found was to incorporate our 'Quad Complementary' output section, discussed in the white paper sent to you by James Tanner earlier. That output configuration goes a long way toward virtually eliminating zero-crossing artifacts from the signal, and sound quality is very improved.
In the future, it remains to be seen whether Class D can achieve the overall musicality that a correctly designed Class AB amplifier can achieve. It is not there yet, but we feel it holds promise.
In today's noisy world, there are challenges remaining in terms of an amplifier's immunity to RF and other noise signals coming in on the power-supplies and input cables. Our latest 'Cubed' models have demonstrated that it is quite important to take that into account as well as overall linearity of a test signal. That's also outside of this discussion, of course, but it matters.
I hope this above is helpful, but please let me know if you have questions or comments.
Best regards,
Chris Russell
Bryston Ltd.
James Tanner - Bryston
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Cubed Amps Advantages
The improvements in each 'Cubed' amplifier model starts at the input buffers. That stage now consists of a new patented super-linear, low noise circuit developed by a partnership between Bryston and Ph.D. engineer Dr. Alexandru Salomie. It reduces noise and distortion in the overall amplifier by a substantial margin. Audible improvements consist of expanded spaciousness and depth of focus, better 3-dimensional presentation, improved midbass clarity, and more top-end 'air'.
In addition, the Cubed Series has much-improved RF and audio-frequency noise filtering before the power supplies to prevent 'hash' on the power line from interfering even minutely with the power supplies or the signal. The audible effect is immunity from power-line spikes and fluctuations, quieter silent passages in the music, 'blacker blacks'.
The improvements in each 'Cubed' amplifier model starts at the input buffers. That stage now consists of a new patented super-linear, low noise circuit developed by a partnership between Bryston and Ph.D. engineer Dr. Alexandru Salomie. It reduces noise and distortion in the overall amplifier by a substantial margin. Audible improvements consist of expanded spaciousness and depth of focus, better 3-dimensional presentation, improved midbass clarity, and more top-end 'air'.
In addition, the Cubed Series has much-improved RF and audio-frequency noise filtering before the power supplies to prevent 'hash' on the power line from interfering even minutely with the power supplies or the signal. The audible effect is immunity from power-line spikes and fluctuations, quieter silent passages in the music, 'blacker blacks'.
James Tanner - Bryston
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28B Cubed Amplifier Philosophy
FIRST TO LAST WATT PHILOSOPHY:
A significant part of the design criteria for the new Cubed amplifiers 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 Cubed 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.
Achieving this 'First-to-last-Watt' fidelity and clarity has to do with a number of design approaches:
• First is complete freedom from low-level crossover, or zero-crossing, artifacts. This is not as easy as it sounds. Most class-AB amplifiers have sufficient bias to prevent primary crossover distortion, but there is another type of crossover artifact called 'secondary crossover distortion', caused by insufficient speed in the driver transistors. We use very fast drivers to prevent this, but more important is Bryston's proprietary Quad Complementary Output design vastly reduces the capacitance 'seen' by the driver transistors, virtually eliminating storage delay in the output stage that could contribute to nonlinearities in the zero-crossing region.
• Second is Bryston's continuing efforts to reduce low-level noise. The clarity of Bryston's designs is enhanced at low listening levels by pushing the noise floor far below the signal level, improving the 'silence between the notes' and enhancing the clarity of the music at low power levels.
• Third is Bryston's concentration on reducing distortion at all levels, and most especially at high frequencies. Bryston amplifiers are perhaps the only designs to concentrate as much effort at reducing HF distortion artifacts as we do, and the results are remarkably 'flat' THD-with-frequency curves, showing almost no tendency to increase distortion as frequency rises. This has the effect of reducing overall 'haze', helping to pull the quietest passages out of the background.
There are other small contributors to this low-level clarity, some having to do with power-supply design for extreme stability, (and in Stereo or multi-channel amps, separated for each channel), which very notably improves the placement-in-space and focus of the sonic 'image'. We think the overall result is an unprecedented degree of clarity and freedom from artificiality, especially noticeable at lower levels in comparison with other designs, but continuing to even the highest outputs.
FIRST TO LAST WATT PHILOSOPHY:
A significant part of the design criteria for the new Cubed amplifiers 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 Cubed 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.
Achieving this 'First-to-last-Watt' fidelity and clarity has to do with a number of design approaches:
• First is complete freedom from low-level crossover, or zero-crossing, artifacts. This is not as easy as it sounds. Most class-AB amplifiers have sufficient bias to prevent primary crossover distortion, but there is another type of crossover artifact called 'secondary crossover distortion', caused by insufficient speed in the driver transistors. We use very fast drivers to prevent this, but more important is Bryston's proprietary Quad Complementary Output design vastly reduces the capacitance 'seen' by the driver transistors, virtually eliminating storage delay in the output stage that could contribute to nonlinearities in the zero-crossing region.
• Second is Bryston's continuing efforts to reduce low-level noise. The clarity of Bryston's designs is enhanced at low listening levels by pushing the noise floor far below the signal level, improving the 'silence between the notes' and enhancing the clarity of the music at low power levels.
• Third is Bryston's concentration on reducing distortion at all levels, and most especially at high frequencies. Bryston amplifiers are perhaps the only designs to concentrate as much effort at reducing HF distortion artifacts as we do, and the results are remarkably 'flat' THD-with-frequency curves, showing almost no tendency to increase distortion as frequency rises. This has the effect of reducing overall 'haze', helping to pull the quietest passages out of the background.
There are other small contributors to this low-level clarity, some having to do with power-supply design for extreme stability, (and in Stereo or multi-channel amps, separated for each channel), which very notably improves the placement-in-space and focus of the sonic 'image'. We think the overall result is an unprecedented degree of clarity and freedom from artificiality, especially noticeable at lower levels in comparison with other designs, but continuing to even the highest outputs.
Mr Peabody
Well-known member
James appreciate the additional information. One other thing, maybe I should have deduced from what you gave, are the Cubed amps differentially balanced?
James Tanner - Bryston
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Paul
Senior Member
Hi James. I'm doing some home audition with your 4B3 amp for last couple of days. Let me tell you I never been a fan of Solid State at all. I owned/tried so many SS amp and gave up few years ago and been only own the tube amplification since. However this 4B3 amp just open up the whole new world to me. I just can't believe the depth , 3D presentation and how smooth it is without losing any details and high without being harsh. I'm so impressed with it and wondering about the 28B3 amps. Now quick question for you I understand you have a gain control on this 4B3 amp and early production of 28B3 with choice of 23 db and 29 db. I just checked the 28B3 you deleted the gain control option. Is there any reason for it ? Also , if I order one is it possible to you can make one with it ?
Thanks in advance.
Sent from my iPhone using Tapatalk
Thanks in advance.
Sent from my iPhone using Tapatalk
James Tanner - Bryston
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Hi Paul
Well thank you for your kind comments and of course I agree that the new Cubed amplifiers really do bridge the gap between the best of solid state and tubes.
The switch is not there on the 28B's as we found with that much power we got better measured performance with the switch out of the circuit. I believe it has to do with the amount of current the 28B can deliver.
I could ask engineering if we could do a special version at 23 if it was needed.
james
Well thank you for your kind comments and of course I agree that the new Cubed amplifiers really do bridge the gap between the best of solid state and tubes.
The switch is not there on the 28B's as we found with that much power we got better measured performance with the switch out of the circuit. I believe it has to do with the amount of current the 28B can deliver.
I could ask engineering if we could do a special version at 23 if it was needed.
james
Paul
Senior Member
Joe . Here you go 
