Sonic Impact - best biamp circuit

[spadulata]

Hi folks,

I've rehoused a Sonic Impact and applied the 'Stealth' mod. Now an excellent amp with input selector etc.

Got the DIY bug and wondered about bi-amping. I don't need more power - just hooked on the sound.

I've read that its better to fit a line-level crossover before the amps and then remove the crossover from the speakers.

I don't know the crossover frequency yet (Tannoy Revolution R1) but it will be fairly standard (1" soft dome tweeter).

I'm looking for the best tweak for the input circuit so that one pot can drive two SI boards (or 41hz). 2 chans hi-pass, 2 chans lo-pass.

Has anyone done anything like this?

Many thanks in advance!

[Pano]

If you choose to use an active filter, the volume control is normaly placed before the filter, so a standard stereo pot is used.

You could place the volume control post filter, but then you get into multigang pots, or VCAs, or digital controls and such. You should be able to get that information on some of the other forums or on the web in general.

[sreten]

Hi,

One particular tweak (which Tannoy goes to some lengths to explain) is the use of an auto-transformer in place of a resistor in order to match the tweeter sensitivity to the main driver. There isn't the space to go into such subtleties here, but an auto-choke is unquestionably the superior solution, and one that's widely used in professional monitoring loudspeakers. Its appearance on a budget 'mini monitor' then is much to Tannoy's credit.

From hi-fi-choice.

Biamping a 3-way with a passive mid/treble c/o makes good
use of the power budget of two identical power amplifiers.

For a 2-way is not so effective, as the tweeter uses little power.
As you would also lose the auto transformer you might need even
less power for the tweeter.

You would need to measure the voltage responses of the
stock crossover at the drivers terminals and replicate them.

/sreten.

[spadulata]

OK, perhaps not such a good idea - I'll get some new inductors to keep me busy instead!

I've also started the tweaks on my CD63KI - It helps knowing whats in your amp when you remove the cd players output capacitors!