MEMO: TO All Bryston Customers
SUBJECT: Upgrades for Bryston SST² Amplifiers
February 2010
Hi All,
We have recently made some improvements to our SST² amplifiers and we will be offering an upgrade package to all our customers.
NEW POWER SUPPLY TRANSFORMER:
In conjunction with Torus Power, we have developed new transformers which are designed specifically to have very high energy storage. This is a considerably more expensive way to design a transformer, but it has clear advantages.
A 'normal' linear amplifier power-supply is made up of a transformer, a bridge rectifier and a set of filter capacitors. The filter capacitors smooth the DC in the rectified waveform, and also store energy to supply large transient current demands from the speakers. The filter capacitors in turn are recharged by the transformer on each half-cycle. However, that recharging takes place on the very peaks of the 60Hz waveform, over only a few degrees of conduction. Thus, although the average current from the power cord is only a few Amperes, it is actually a series of very narrow, very high peaks of current, as much as 50 Amperes or more per half-cycle.
Those high, narrow peaks of current have a consequence. They equate to drops in Voltage from the power cord, from the wall socket, from the wiring in the house. A transformer designed for energy storage solves those issues. It recharges the filter capacitors directly from its own energy storage capacity, and then takes up the energy from the wall socket over the entire 60Hz waveform. Gone are the narrow peaks of 50+Amp current, gone are the Voltage drops, gone is the negative consequence of restricted instantaneous power delivery.
So all ‘NEW’ versions of the 14B SST², 7B SST² & 28B SST² incorporate these power supply changes. These transformer changes do not apply to the smaller versions of the amplifiers (2B 3B, 4B, 6B, 9B) because the advantages of this technology really only apply to very large power amplifiers with large power supplies.
2. INPUT CAPACITOR CHANGE and FEEDBACK CAPACITOR CHANGE:
We also implemented the use of some very specialized capacitors in a number of key areas in the circuitry. There is a consistent improvement at high frequencies near and above 20K, and up to over 60KHz. These specialized capacitors are installed at both the input stage and the feedback loop of the amplifier circuitry. These capacitor changes are included in all new SST² amplifiers.
The upgrade is only available for ‘SST²’ amplifiers ‘NOT SST’ or previous models.
At Bryston we are continually trying to improve the performance of our products. Please be aware that these changes are 'evolutionary' not 'revolutionary' in nature. They will provide subtle to noticeable improvements depending on your specific system and setup.
Upgrade Prices:
7B SST² upgrade includes new transformers and capacitors:
This only applies to 7B SST²’s below serial number 001826.
14B SST² upgrade includes new transformers and capacitors:
This only applies to 14B SST²’s below serial number 000677.
28B SST² upgrade includes new capacitors ONLY:
This only applies to 28B SST²’s below serial number 000180
Please contact Bryston at mpickett@bryston.com for any assistance.
