[PavelL]

Having read this http://www.bryston.ca/28bsst_m.html
leaves me wondering as to what 4b SSt thd+noise is at 1Wt, 10Wt, or 1/3 of rated power  All the readings in the checkout sheet are at maximum rated output...

[James Tanner]

Hi Paveli

The THD will increase slightly, though at lower power levels the tiny bit of THD disappears into the noise.

Chris

[Burke]

...the tiny bit of THD disappears into the noise.

So how much (measured) noise is there at 1 watt, 10 watts, or 1/3 of rated power for the 4B SST? It would be interesting to know the same for the 7B SST as well.

Thanks,
Burke

[James Tanner]

...the tiny bit of THD disappears into the noise.

So how much (measured) noise is there at 1 watt, 10 watts, or 1/3 of rated power for the 4B SST? It would be interesting to know the same for the 7B SST as well.

Thanks,
Burke

HI Burke,

All Bryston amplifiers show extremely low THD across their complete power band range.  That is why they sound excellent at low power as well as full power.

As the power is reduced the noise floor becomes a greater ratio of the THD measurement and even falls into the noise floor of the test gear. It is really difficult to get big power amplifiers to sound fast and open at low power settings - in fact Bryston amplifiers have a power band spectrum that looks more like a preamplifier than a typical power amplifier. I also think this issue is why some people generally feel lower powered amplifiers sound better than big powerful amplifiers.


I will ask one on the techs to give me exact numbers for you.

james

[john1970]

...the tiny bit of THD disappears into the noise.

So how much (measured) noise is there at 1 watt, 10 watts, or 1/3 of rated power for the 4B SST? It would be interesting to know the same for the 7B SST as well.

Thanks,
Burke

HI Burke,

All Bryston amplifiers show extremely low THD across their complete power band range.  That is why they sound excellent at low power as well as full power.

As the power is reduced the noise floor becomes a greater ratio of the THD measurement and even falls into the noise floor of the test gear. It is really difficult to get big power amplifiers to sound fast and open at low power settings - in fact Bryston amplifiers have a power band spectrum that looks more like a preamplifier than a typical power amplifier. I also think this issue is why some people generally feel lower powered amplifiers sound better than big powerful amplifiers.


I will ask one on the techs to give me exact numbers for you.

james

James,

As a fellow 4B SST owner I would also in interested in the specs of the 4B SST at lower output.  Thank you for making an excellent product.

Best,

John

[James Tanner]

OK here are the results from a typical 4B SST and 7B SST.

4B SST
Frequency     1W     10W   100 W   300W
20Khz           .01     .008   .003     .004
2KHz            .01      .008   .002     .002
200Hz           .01     .008   .002     .001
20Hz            .01      .008   .002     .002

7B SST
Frequency     1W     10W   200 W   600W
20Khz           .01     .006   .003     .004
2KHz            .01      .006   .002     .002
200Hz           .01     .005   .002     .001
20Hz            .01      .006   .002     .001


As you can see the THD at the 1W reading is the same at all frequencies which indicates that the noise floor of the amplifier and test gear is dominating the reading.

james

[Burke]

James,

Interesting figures. Thanks for sharing that information. Basically confirms what I've heard (or HAVEN'T heard) :>) listening to the 4B SST and 7B SST power amps. They are nuanced performers, with no discernible noise, at low volumes where their prodigious power output capabilities aren't really being touched.

Burke

[Hififreak]

Hi James,

Can you also show me the results of the 14B SST?

The set

[James Tanner]

Hi All,

Thought you might be interested in this.  These are measurements taken from a recent April 2007 review in a very prestigious German magazine called STEREO.

Bryston 14B SST Power Amplifier
Once more an overview of the power output:
613 watt sinusoidal per channel into eight ohms, 2 x 1437 watt momentary into four ohms at an output impedance of only 14 milliohm.  With this the amp can accommodate any loudspeaker.  On top of this Bryston succeeded in pairing high output with minimum distortion: .0017 to .0006 percent distortion between 50 milliwatt and 1 decibel under full output.  Intermodulation distortion is barely higher: .003 to .0043 percent. 

Very high signal-to-noise ratios from 99 and 79 dB. (5W/50mW) complement the positive impression.  The channel separation is an exorbitant 90 dB. at ten kilohertz, and that with both powerhouses in one cabinet. How do the Canadians accomplish this?  

Bryston BP26MC Preamplifier
With the distortion measurements our analyzer primarily spit out zeros.  Hence  with .03, .3, and 1 volt output distortion amounted to .0027, .0003, and .0002 percent. 

Even with intermodulation distortion under the same conditions hardly more could be obtained, i.e. .0065, .0012, and .0011 percent.  Superb! 

The unweighted signal-to-noise ratios of 95 and 74 dB with .3 and .03 volt are impeccable.  For the phono stage with .3 volt it was still 81 (MM), and 58 dB (MC).  All input values are appropriate for their use.

High channel separation of 70 dB, very minute tracking differences of the volume control potentiometer from .3 dB down to -60 dB.  We measured damping between input and output signals at 81 dB.  The idle power consumption is about 15 watts, and the output impedance 72 ohms.
Impressive


james