BritInVA Construction Thread - Page 40

If they were, everyone would be really paranoid.

I'll have time to post the parts list tomorrow. Sorry I didn't get to it today. I think I spent around $400 for all the parts including the BFD. In the grand sceme of things, I saw it as a necessity to get my space tuned up. BPape will need the data to design the treatments.

No worries. Thanks, Michael. No hurry. I just want to understand this stuff.

Got a pointer to some info on decyphering the curves and room tuning in general?

Thanks, again.

CJ

Mark,

Which model did you buy?

Bill

I picked mine up last spring from Guitar Center for a very good price. I was also able to get the patch cords that you will need for the connectors on the back (large phono plugs).

When you get your BFD and are running REW, make sure you measure in a couple different locations first to get a better idea of the room acoustics. That dip you see at 57 Hz may be related to an 11.8 ft dimension somewhere in your room and you really can't boost that much using the BFD. IMHO, you can only boost very small amounts to make up for a small deficiency in the sub, but I wouldn't try to boost out a null. You may be surprised how how moving 2 feet in some direction (up/down, left/right) changes the graph.

With REW you can average several close locations and set the filters from that. I think it will give you better results in terms of widening the sweet spot.

Good Point Greg!

Mark, Try running a continuous test tone through the sub and walk around the room. Chances are you'll hear a dip in the SPL in one or two locations.

The two things I suggest you read is the REW guide and the BFD Guide. Both can be found on the Home Theater Shack.

You may know this already, but the BFD stands for Behringer Feedback Destroyer. It's a bit of cheap (~$100) equipment that is designed to be used in concerts to find and eliminate feedback. Sub builders/tuners however use it as a cheap equalizer. The guide on the shack covers a lot of the basics and does the REW guide. Don't get stressed if you get lost while reading either guide. This stuff is a pain to figure out without actually at the same time physically taking the samples and playing with the equipment.

REW is designed to just test and equalize subs and your mains. If you wanted to equalize other channels, you would need to hook up that speaker as your main to do the testing and (I guess) get a separate BFD to equalize them. If you want to manually equalize your entire system, I would invest in a real equalizer.

Really, REW shines for fixing bass and main cross-over related issues.

Hello Mark,

I see you are using the M-Audio MobilePre for your REW setup. I also have the MobilePre and am having some issues getting REW to work. I stated using REW with a Vista laptop and have since switched to an XP machine just to eliminate any issues Vista may cause.

When you go into Settings in REW and select the MobilePre for Output Device, what did you select for the Ouput (the box directly below)? Also same question for the Input box directly below the Input Device box?

Finally, did you use 44.1 or 48 for the Sample rate?

Thanks,
Rich

I agree, and since you have the Denon 2807, I would use that for equalizing the mains and surrounds. The Audyssey routine should be decent for that, and much better than using a parametric equalizer like the BFD. I would recommend you use all 6 listening positions of the Audyssey setup, even if you measure the same 3 points twice (which is what I do). I do the main listening position, then slightly left and right and repeat until I have accumulated the maximum listening points allowed.

The BFD is only good for the sub range, where some versions of Audyssey are not so good.

Congrats on the new toy! As for Audyssey, I am not familiar with the Denon implementation, but I have been quite happy with it on the Onkyo 805. In fact, I will probably sell my 1124 and all the cables, soundblaster, midi adapter, etc. at some point in the very near future. You do have to be very quiet, use a tripod, stay away from all surfaces and walls, and it should do a very nice job. It has the advantage of being able to make adjustments based on an impulse response, for direct as well as reflected sound. You can also bump the trims if you don't like the results. Some like the subs a little hotter, or the center bumped to help with the dialog, etc.

Mark,
This white paper is what a lot of people use for subwoofer placement guidance:

http://www.harman.com/wp/pdf/multsubs.pdf

Scroll down to the Conclusions and try placing 1 sub in front center and 1 back center. Put the back one in front of your bar and try taking a sweep (measurements).

Mark,
I was thinking that once you found a spot where you got a good response you could then think about hiding the sub.

If it works best in the back center then one way to hide it would be in the bar. But, that would require a lot of rework and most likely a custom enclosure for the sub.

I guess it really depends on how important it is to you.

Thanks... hopefully i can get this thing to work right.

Mark:

Maybe I missed it, but could you describe what you are trying to work out? What do you think is lacking in your system and how did you come to figure out what it was? It may help others of us work out our own setups (or future setups) by learning from your experience.

CJ

AHA. When I last got together with some of my HT friends, I was telling them that each time I visit a theater, it gets a little more expensive.



CJ

- I didn't do it!!!


Ok - Mark, you have to stop using that Audyssey calibration.

All of your speakers should be SMALL...not LARGE as Audyssey likes to make them.

When they are large - they will try to have more bass and that adds distortion. Let that HSU monster tackle all the bass.

I recommend just using Avia and the rat shack SPL meter. I did that to program my Denon receiver and it sounded way better than the Denon Audyssey programming.

Mark - my sub is in the right corner if you are looking at the screen and the ports fire across the screen to the left corner. Have you tried this port position yet?