I'm not a big fan of HT (home theatre) bypass in a stereo preamp, and I'm also not a great fan of balanced operation (see previous post for reasons) but I realize that for many people these options are a necessity, and I've offered both HT bypasses and balanced outputs in my preamps for many years.
As I've explained, true balanced operation via a centre tapped transformer is the purest and most transparent form of balanced , and is the only method I use.
Suhendran needed to integrate his HT system with a Supratek preamp, but he also recognised the advantages of using a Dual Cabernet preamp to bi-amp his speakers.
Any speaker with seperate connectors for bass and mid/treble can be bi-amped , which provides a good performance boost, but with the Dual Cabernet, and its two seperate line-stage circuits, with level controls for each, its possible to adjust the levels so as to adjust the bass and treble to get a perfect setting for achieving the ideal tone for room and personal taste.
No passive crossover in any speaker is perfect for all conditions- they are all compromises, but the Dual Cabernet lets you dial in exactly what is best for your room and taste.
Suhendran's design request was a little different as both of his power amplifiers were XLR input connections . The Dual only has one set of XLR output , so we decided to sacrifice the preamps input XLR and use that as the extra output XLR.
Both of these output XLR's had to be switched into the HT bypass circuit, which is easy enough to do on a printed circuit board, but quite a job with hard wiring , nevertheless it worked out well.
Suhendran also wanted to use a DSP (digital sound processor) on the bass amplifier , in order to do some bass EQ for room correction, so I put a loop into the linestage circuit which will be used for bass.
The advantage of this is that you get the benefits of DSP in the bass spectrum, but it doesn't affect the mid/treble region, no opportunity for digititus in the ear!
Here's a diagram of the preamp integration.
And here's a pix of completed preamp. Its finished with ebonised black wood cabinet and satin black chassis, to blend in with all black component system.
Worked out well, but a lot of work!
