Originally Posted by craig john
Editorial comment: In the future, it would be best to start your own thread, with a title that explains your questions. That way you will get more and better responses. Also, others with similar questions to yours will be able to search and find your post.]/QUOTE]
B&W 802D right and left front
B&W HTM2D center
B&W 805S right and left surround
2-Paradigm Signature Sub 25's
Krell Evo 707 Processor
Krell Evo 600 mono block amps for right and left front speakers
Krell S275 bi-amped to center channel speaker
Krell S275 for riight and left surround speakers
The room is 12" X 18", cathedral ceilings 12" high. There is one over-sized door way (approx. 6' 9" tall X 3' 9" wide).
Well, do you now see why a separate thread is appropriate? We've gone from an Axiom bookshelf system to a full blown B&W tower system, and from a Marantz receiver to a Krell "separates" system. Your questions are very technical , but totally unrelated to the original topic of "To Much Sub?"
Anyway, let's take your questions one at a time:
1) Set all speakers to cut off all frequencies below 80Hz, and send all frequencies below 80Hz to the subs (despite the fact that my right and left front speakers are full range and my center channel speaker will go down to 40Hz +/- 3dB). I have done this and it has improved the sub performance.
There are several reasons to engage Bass Management, (which is what you are doing when you set crossovers on the speakers.) First, your speakers are not *quite* full range. They are -3 dB at 34 Hz and -6 dB at 27. While that's good for a speaker, it's definitely not subwoofer territory. A good subwoofer can get to 20 Hz and below. Also, your CC is -3 dB at 40 Hz. There is a whole octave of sound below that, and even more below 20 Hz. Certainly some program material has content in the CC that low. If you don't send it to the subwoofer, and the speaker(s) can't reproduce it, it's lost, never to be heard.
Second, the speakers *need* to be placed where they image the best. That placement is rarely the best placement for bass response. The subwoofer(s) can be placed where they best interact with the room for bass response. Re-direct the bass to an optimized subwoofer system and you'll have a much better chance of hearing and feeling all that good bass.
Third, if you relieve the speakers and amps of the burden of reproducing the deep bass, you free up amplifier headroom, and woofer excursion for the rest of the speakers' bandwidth. This may not be a big deal for you with those massive Krell amps, but more headroom is always better; lower distortion, more max output, etc. You may feel like you're "castrating" your speakers by taking away all that bass capability. Never fear... those is lots of bass in the output above 80 Hz. Your woofers are crossed at 350 Hz. There is over two octaves of bass in that range. Your woofers will play it more cleanly if they don't have to cover the next two octave below 80 Hz.
I agree with your "self proclaimed bass and HT expert" that it is worthwhile to use Bass Management, even with bass capable speakers.
Originally Posted by matjet
2) He advised me to set all speaker distances to 0 feet and set the sub distance to 9 feet even though the sub is located two feet behind the right and left front speakers. I tried this set up, and amazingly, it seems to work well despite the fact that this set up contradicts my processor instruction manual. The room seems much smaller with the standard distance set up (measuring each speaker distance to the prime listening seat). The room feels much larger (like the walls have been removed ie: expanded sound stage), and the system actually sounds a bit better with all speaker distances set to 0 and subs set to 9 ft.. This is puzzles me.
It's a little puzzling to me also. I understand what he's trying to do, but I'm not sure how he arrived at this recommendation. Setting distance is actually setting delays for all the speakers. If you set the subwoofer furthest away, it will fire "first". Then all the other speakers will be delayed an appropriate amount of time based on their distance settings to allow them to fire when the subwoofer's wave is exactly in-phase with them. Then all the sound waves from all the speakers will arrive at the listening position at the same time.
Setting the subwoofer furthest away is usually done when there is some latency in the subwoofer. If there is a low pass filter or an EQ, these will cause latency. Are you using the Low Pass Filter? It has a bypass mode. If you bypass it, I can't see anything else in *your* sub that would cause latency. (If you are using Bass Management, it has a LPF for the subwoofer built-in, so you don't want to, (actually *shouldn't*), be using the sub's LPF along with the receiver's. Bypass it.) Anyway, ask him why he suggested 9', and why he wouldn't want all the other speakers set to their physical distance.
Originally Posted by matjet
3) He told me to plug up the ports in my speakers (Paradigm Signature Sub 25 is a closed/non ported sub). I haven't tried this yet.
The ports in speakers are "tuned" to a frequency of resonance. That frequency is slightly above the -3 dB point of the speaker. The port itself has very little output above or below the tune frequency. However, the port output, by definition, is out-of phase with the drivers. This can cause some transient response anomolies. You can also get some port "noise" caused by the air rushing in and out of the port at high volumes. If you cross the speaker over to the sub well above the port's tune frequency, you don't use the ports anyway, so plugging them will make the speaker a "sealed" speaker. Some folks prefer the sound of a sealed speaker, but I can't say what your speakers will sound like with the ports plugged. It's worth a try.