DSP Active Crossover

@simonmoon wrote:

I’ve heard several systems with the mini DSP, and have been unimpressed.

I’ve also heard several very high end DSP systems, including the Kyron. And that system kills! Even Mr. analog, Michael Fremer loves it.

But my overall evaluation is, that it takes a very special DSP speaker system to best the best passive system.

It’s not as much the DSP unit as it is the implementation. My IIR-based DSP unit cost me just over just $1,000, and it’s an excellent piece of equipment for what it’s supposed to (make me) do, and one that also holds up perfectly well to Lake units (costing much more). That’s for nothing however if you don’t know how to turn those settings into proper, audible effect, of which there are different routes for that to be accomplished. I still prefer setting DSP-values manually by ear with the aid of measurements (and input from friends), and while a painstaking and lengthy process the results can be, and actually are extremely good.

Of a range of passively configured speaker setups I’ve heard that were converted to outboard active configuration - that is, bypassing their build-in passive crossover completely and replacing them with line-level DSP’s/electronic XO’s and more amps - each and every one of them eventually saw a substantial upgrade in sound quality over their passive iteration (and that was obvious fairly early on), to everyone listener involved. That’s all I need to know and a testament to the potential of active configuration, not least from the important basis of comparing the same speakers with different filter configurations.

Many are, on principle, against DSP due to speculated, negative effects of A/D-D/A conversion steps with analogue inputs only, but with no experience to really speak of that would actually single out this particular aspect as the detrimental factor. Why even make any assumptions as to what may or may not, technically, be the reasons for a speculated deficit?

One of the best setups I’ve heard, an outboard active one at, comprises the exact same DSP unit I’m using. For anybody wanting to tell me it’s an IIR-based filter and not a FIR ditto, while implying perhaps it’s the lesser solution, I can only stress the importance of seeing the forest for the trees in actually listening to a properly implemented active setup and let your ears decide. Should the FIR-filter hold the upper hand sonically, which theoretically it does not least in being able to generate linear phase response, that’s only an added bonus that will potentially distance active from passive even further.

The minidsp SHD (2 way digital xover) uses an ESS 9028 DAC chip......pretty good. The Audiophile Junkie (see his Youtube channel) uses this Minidsp SHD in his super system. I posted this on a couple of other threads.....but I cannot stop talking about this....so here goes again.

I have been quietly following this thread. have a feeling that the OP will be thoroughly disappointed with the minidsp SHD since he appears to be used to a Denafrips dac and whatever preamp he’s got.

For my attempted application, i tried to replace the Denafrips Hermes+Venus and a Yamaha C5000 with the minidsp SHD in pursuit of an active crossover. The SHD is awful in comparison and i just got rid of it.

To each his own....(with the theory crafting n all).

I would be willing to bet that most active speakers with DSP still have some degree of passive crossover networks prior to the electrical connections on the speaker.  many drivers require a simple impedance flattening or notch netwok to rid the driver of response peaks. 

if your your active drivers need impedance flattening, notch filters or if the speaker has baffle step compensation you are fighting an uphill battle trying to use only DSP to address those issues. 

if your your active drivers need impedance flattening, notch filters or if the speaker has baffle step compensation you are fighting an uphill battle trying to use only DSP to address those issues.

@Avanti1960, having built both, I can say this is not at all the case. In all cases, impedance flattening circuits such as a Zobel, increase power required for the sake of making the crossover work closer to an ideal state, like it would with a resistive load. I can categorically state this is completely unnecessary with a DSP based amplifier and crossover. It’s one of the major benefits of designing active speakers that you can ignore the impedance of the drivers.

Another way to say this is that in a passive speaker I only care about impedance flattening because of the effect rises and peaks can have on the frequency response. With DSP, any such issues I can deal with directly in the EQ.  THe point is moot though because with an excellent plate amp the impedance curve of the drivers just doesn't matter (so long as it's high enough).

There are hybrid speakers, which use both active and passive crossovers but I think these are becoming rarer with the common availability of 3-way plate amplifiers. IMHO, and not all speaker designers will feel this way, there’s no upside to a hybrid system if I can go fully active.

The baffle step compensation you reference is a frequency domain issue as well which is quite easily dealt with by a DSP EQ instead of with additional passive components.

Another great advantage for the designer of a fully active instead of a hybrid system is the ability to digitally delay each driver independently and achieve a quasi point source output with high order filters giving you most excellent on and off axis response which you’d have trouble with a hybrid.

The flexibility of a DSP based crossover sometimes causes bad choices though, such as picking bad sounding or poorly matching drivers and then hammering them into shape with EQ, as well as using global EQ to fix bad crossover choices.

You sound ready to take the next step in building speakers, so I really hope you get excited and build some for yoruself soon, either passive or active.