Marbles -
So how is the testing going? Was Dennis able to better his passive XO with "The Future"?
Thanks for your thoughts on the DEQX and HT3a's.
It was an interesting day yesterday. Dennis and I spent the day measuring, calibrating and setting up crossovers and in-room EQ.
What follows is my impression of where we ended up. While I can't speak for Dennis, I think we were in basic agreement. But you may want to ask him to see if his impressions mirrored mine.
From the midrange on up, there was little or no discernable difference between his passive crossover and the DEQX corrected (active) set-up. Since you have his passive crossovers in your HT3's, you pretty much know how this end of the active set-up sounds.
We did use steeper slopes on the DEQX version and, thus, were able to cross slightly lower. This should have improved imaging and sound stage slightly. And it may well have, but the differences were so minimal as to not be readily discernable.
The mid-bass on the DEQX set-up was slightly more full sounding than the passive crossover version. Here is what I think may account for the difference:
Many subwoofer drivers have a slightly rising response below 100Hz (at around 70Hz for example). If you are crossing at, say, 250Hz and you set that level at that point equal to the midrange, there will be an excess of energy in the area around 70Hz (in this example). So you set the relative level of the woofer so that the 70Hz rise (in this case) is in proportion.
What you end up with is a slightly depressed area in the 100Hz - 200Hz range. We are talking about a small difference here, but one that is audible.
With DEQX, since it can and does adjust the response up or down as needed, it can compensate for these variations in response. So in the DEQX version, the 100 - 200 Hz area is not slightly depressed as with the passive crossovers. Thus, the mid-bass region will sound slightly more full. DEQX may also be compensating, somewhat, for some floor bounce cancelations in this frequency range.
At any rate, that is my current theory supported only by listening tests.
The other major difference is in the area around 40Hz where room modes come into play in my room. With DEQX, you are able to cancel these out by applying EQ. So the low frequencies are slightly better controlled.
Relating to an earlier question, can the same results be achieved with a TacT unit using a 2-channel amp and the passive crossovers? The answer is yes for the low bass anomolies caused by room modes. But I am not sure about the slight mid-bass depression (although it is certainly possible).
While it was not quite ideal, the HT3's I was using did allow us to do some A/B listening tests (although the change-over times were not as fast as we would have liked). Both the active and passive versions sounded very, very good. And I came away with a renewed appreciation for just how good a job Dennis did on the passive crossovers.
As I said before, Dennis may have a slightly different interpretation of the results. But one thing is certain, we have a DEQX set-up that is very good indeed and I will have it available to demo at both the Rocky Mountain Audiofest and the Chicago Audiofest.
I would also like to publicly thank Dennis for his contributions to both projects. He is a true artist in every respect and anyone who has heard the HT3's can attest to that.
Marbles, I hope this answers your question.
- Jim
