Ground Sound- Interesting active filters?

[weedogt]

I found this interesting site:
Ground Sound

Especially the digital filter (DCN23) seems very interesting. Have anybody tried it?

[Irwin AR]

The owner himself had previously introduced his product here

Introducing Ground Sound

interesting.

[Duck-Twacy]

I wonder if that new DCN26DAV Xover is still under construction....

[Robert GS]

Hello all.

We are still developing a new crossover, but things have changed a bit/byte. The working title of the crossover is DCN28DAV, which indicates 2 input channels, 8 output channels, digital in and analogue in and volume control. I think we are nearly there, but we still have some issues.

In the meantime you can read a review of our Chassis 1500 in the next issue of Hobby HiFi from Germany and a review of our power amplifier module PA3CC in Elektuur/Elektor September issue.

[Duck-Twacy]

Sounds already great

[FullThrottleRic]

Originally posted by Robert GS
The working title of the crossover is DCN28DAV, which indicates 2 input channels, 8 output channels, digital in and analogue in and volume control.

That sounds perfect for my next project

Will it have single ended analogue inputs?

[Robert GS]

Will it have single ended analogue inputs?

The analogue inputs will be balanced. If you want to connect a single ended signal you just short the inverting input to ground or you can make a balanced cable with a small 100R resistor in the RCA connector at the pre/processor end. The 100R resistor emulates the output impedance of the pre/processor and has to be connected between inverted wire and ground. I call it “pseudo” balancing and this way the differential input will balance out the noise from the cable just as an active version would.

The digital inputs options will be 2 S/PDIF and 1 balanced AES. We might make a possibility of optional optical TOS link.

The outputs (only analogue) will be "pseudo” balanced.

[Javachip]

What type of crossover does this product use? Is it a digital implementation of a Linkwitz-Riley crossover, like the Behringer or the dbx, or is it a FIR design, like the DEQX or Juice HiFi?

If my question contains any errors, please correct them.

[phase_accurate]

It is almost freely configurable with a GUI running on your PC.

One of the great advantages of digital x-overs is the possibility to achieve transient-perfect crossovers. A nice topology to achieve that would be the subtractive-delay type (After Lipshitz & Vanderkooy, nice spreadsheet by John K available).

Robert: When are you going to implement this topology ?

Regards

Charles

[Robert GS]

The processor will be capable of doing both IIR and FIR. I’m not sure how the configuration will be as FIR filters calculations demands roughly 20 times more that IIR does of processing power. If FIR is used one will have to settle for less eq points etc. I would say that one has to focus on the weakest point in the system and I hope everyone can agree that it’s the drivers/loudspeakers. Focusing at the speakers will dictate measurements of the system and not to forget the room too. The software we provide for the DCN23 and the new crossover is supporting measurements import, which we find crucial for the system performance. We don’t consider using only FIR filter as the best solution. A blend of IIR and FIR will give some advantages.

The subtractive delay type filter presented in an AES paper from 1981 is a bit obsolete theory from my point of view. It focuses on the filter response and function, which doesn’t make much sense when considering that ex. tweeter and bass doesn’t have the same impulse response and also mounting will influence on the result. It is beautiful is theory, but lack performance in the real world. In the 1980ies I actually implemented a system with the subtractive delay type filter design, but it did not outperform a “normal” filter design at all – of course it was analogue.
I will still claim that the key to a good system performance will be to focus on optimization of the speakers from good measurements.



Sorry - I just had to ad some smilies