At first I thought it must be a typo (15 MHz should have been 1.5 MHz like the 30SS spec), but then I noticed that the DC to 2.5 MHz spec is -.10 dB (down only 1/10th dB instead of 10 dB). So the numbers as shown might be correct, and if so show a much more extended bandwidth, being down 3 dB at 15 MHz instead of at 1.5 MHz.
Utilizing recent breakthrough understanding in high-speed transistor behavior, new semiconductor designs exclusive to Spectral address historic limitations in amplifier linearity and banish low-level distortion products to previously unattainable levels. These devices and a new family of exotic custom made passive components are utilized in a new generation of high-speed, wide-band input stage and high-level line sections with unprecedented results.
The "thermal tails" stuff is old news. It used to be new when the world switched from hollow state to solid state and wide band, open loop, amplifier were the last frontier. Probably a long forgotten issue for engineers using ICs almost exclusively nowadays. Not sure how applicable to modern topologies could be...
Bandwidth alone, whether 1.5Mhz or 15MHz, doesn't tell the whole truth. A settling time specs has never been published AFAIK.
The SHHA module had a facelift with the introduction of the metal can dual J-Fet. I'm quite sure this is a re-badged LSK389C from Linear Integrated System. All the previous iteration of the SHHA module used the unobtanium National NPD5566.
"Developed exclusively for us": no way. Repackaged? Maybe.
Cannot comment on the teflon trimmers and polystyrene SMT caps. Too small to see, all the SMD caps looks the same but quality can differ by orders of magnitude.
The new balanced input board is the real news here. It would be interesting to see a close up picture.
Complimenting the high performance SHHA driver in the DMA-300 is a new and advanced gain stage which features custom semiconductor technology developed for high-resolution display applications.
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In this configuration, the custom gain devices deliver nearly twice the speed of previous Spectral gain sections
Nelson Pass has a new SiC (silicon carbide) based VFET device and new amp designs based on it. Pass calls the new VFET device a Static Induction Transistor and his First Watt company will be releasing both a monobloc and a stereo amp based on the SIT. Will be interesting to see if it is a device that can back-designed as replacements into the many dead Yamaha and Sony VFET amps out there. He does credit Yamaha and Sony for the initial work. Stay tuned.
Somewhat old news (http://www.semiconductor-today.com/news_items/2011/JULY/SEMISOUTH_300711.html) but yes it's great to see these wonderful devices being rediscovered. Whether or not SemiSouth will make a selection of them available for audio use remains to be seen I guess ... but I kinda doubt it given the limited market and the high production costs.
I believe Nelson had his custom made for a small fortune and at the moment there's no compliment for it.
As always, I'm more than happy to be proven wrong. :thmbsp:
May 19, 2010: "I'm in the process of spending six digits on a small run of special Jfet power amplifiers, my own version of the 'SI' Vfets you may recall from the Yamaha and Sony efforts of the 70s and related to the Digital Do Main product showcased recently on your site. Remarkable parts. Their curves look like triodes, with an output conductance on the order of 4 to 8?.
"You may recall my mentioning that last year I negotiated with SemiSouth for a custom lot of Silicon Carbide (SiC) power Jfets known as Static Induction Transistors (SIT).
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