Preparing for REW+BFD

**Trekari** · **02-02-08, 02:13 PM**

WHile I wait for the postman to deliver the remaining cables I need...

Right Main+ Right Sub, Phase 0, Xover on Subwoofer maxed, using LFE input of Sub (so xover is bypassed on it anyway), LFE Xover in receiver is set to 120, Xover of MAINS are set to 120.

**brucek** · **02-02-08, 02:27 PM**

Post graphs with a vertical scale of 45dB-105dB.

Why are you using a crossover of 120Hz instead of 80Hz?

brucek

**Trekari** · **02-02-08, 02:29 PM**

Because 80 didn't look too great.. I'll post that too (blame REW for changing my scale on me all the time, my apologies).

**HClarkx** · **02-02-08, 02:34 PM**

I agree, I'd stick with an 80 Hz crossover. But, are you sure the main amp is turned on?

Or is the sub gain pushed up too high?

Something is awry. Maybe crank down the sub gain until you are fairly flat from zero to 200 with the crossover set at 80 Hz. Push the receiver gain up to compensate for turning the sub gain down.

Harrison

**Trekari** · **02-02-08, 02:50 PM**

Using the Aux input, my max speaker volume is about 72dB. I did in fact have the sub "pink noise" calibrated to about 73-74. However this needs clarification:

I calibrate my speaker volume using the internal Onkyo test tone inside it's "Speaker Level" settings page. Every satellite speaker is set to 75dB via that page. The sub was adjusted within that page as well to 73-74dB.

Using the AUX input, I am only able to produce (at max volume) 72dB using REWs speaker pink noise with the satellite speakers. The sub may have been a little hot, but not more than 1-2dB IMO.

Perhaps one of you can explain why you want me to use 80Hz? Here are my reasons for 120Hz at the moment.

1) I have two subwoofers, which means I can get a more flat response from those frequencies produced by the subs, than I can any other individual speaker.

2) I have a Behringer ready and waiting to use with the sub channel, whereas I cannot do any post-Audyssey EQ on any other channel.

3) The subs are right at the feet of the main speakers, so localization is not a big deal IMO?

It would seem wiser to me (I'm no expert) to use the subs to produce as much of the frequency response as they are capable of since I have the ability to correct the subs.

*EDIT*

Ok, I could see where localization could be an issue if only the Right main is supposed to have a 100Hz tone, whereas sending it to the subs would produce it on both sides of the TV.

**HClarkx** · **02-02-08, 03:11 PM**

Jason, you make very good arguments for a 120 Hz crossover. Another is that the more load you can take off the mains, the better.

Your mains do have some ups and downs above 100 Hz that might be too much for Audyssey and I agree that if the BFD can handle them, that would be fine. In fact, that argues for an even higher crossover. I wouldn't question 180 Hz if it works.

You do have a nasty 130 Hz dip in one of the subs that I'd be inclined to avoid. But, if that doesn't show up as much of a problem once you have combined the mains and subs, or the BFD can handle it, I'm with you.

I'd still be inclined to start with 80, see what you have to deal with there, look at 120 and see how that compares (you say it's better but I'd like to see it) and maybe try 160 or 180 to see if it gets even better.

It all depends on what Audyssey can clean up. Audyssey does have limits on what it can do, but within it's limits, it's very accurate (frequency and time domains especially). It's biggest advantage over the BFD is probably it's 10 ms time alignment capability. That can do wonders for blending a sub and main.

So, I guess if you really want to optimize the crossover choice, you would try 80, 120, 160 each with Audyssey run with all 8 measurements. That's a lot of work though.

A sequence of 80, 120, 160 with Audyssey off would be very interesting to see.

But, it needs to be with that massive upper-end roll-off fixed. I'm still not clear on what's going on there. Until you see fairly flat from 10 to 200 (and preferrably to 300), I wouldn't worry about optimizing the crossover.

Harrison

**brucek** · **02-02-08, 03:16 PM**

Quote:

explain why you want me to use 80Hz? Here are my reasons for 120Hz

Anything over 80Hz results in localization of the sub. You really don't want that. The only reason to use a cross greater than 80 is when you have little satellites that can't handle low frequencies - not your case... use 80 or below.

brucek

**Trekari** · **02-02-08, 10:06 PM**

Sorry, spent the day with friends. I'll get some graphs going again in the near future post-Super Bowl.

(I also kind of just want to enjoy what I have for a few days in between graphing sessions

)

**HClarkx** · **02-03-08, 02:09 AM**

Bruce makes a good point, but you will know if localization is a problem and can backtrack if that happens. But, since your subs are within a couple feet of your mains and inside of your mains, localization shouldn't be any worse than it would be with a large full range speaker with its big woofer on the bottom. I.e., any localization is unlikely.

Enjoy the Suberbowl.

Yes, do enjoy what you've got, it probably sounds a lot better than the plots would seem to indicate.

Incidentally, since your right sub performs a lot better than your left, and in fact better than both together (it's within +/- 4 db up to 100 Hz with one small exception), you could return the left sub and be quite happy. The second sub does add 6 db to your low end capability, but I'd guess just one sub could easily get you kicked out of the building if you really exercised it. But, I'm not suggesting you return one, just tossing out the possibility. Sharing the load on the two subs reduces risk of getting into any nonlinearity the subs may present as they are driven harder. And someday you might want that extra 6db. And two of them reduces the likelihood of localization (you might want to stick with 80 Hz crossover if you had just one).

Another thought. Some people argue for putting the second sub behind you or something close to that. I tried it and didn't like it (and it didn't equalize as flat). But, that's what they say. My son had an extra sub and put it next to his sofa pointing into his sofa. The sofa really shook on the lows. Kinda like those shaker things they make for sofas.

Harrison

**brucek** · **02-03-08, 10:15 AM**

Quote:

localization shouldn't be any worse than it would be with a large full range speaker with its big woofer on the bottom. I.e., any localization is unlikely.

Full range speakers are in stereo, and create a soundfield. That's a big difference from a mono sub signal that is easily localized to a point source....

Quote:

you could return the left sub and be quite happy

Or simply co-locate them, which is one of the better methods of running two subs. Find the best spot for one sub and co-locate the second to increase the headroom.

brucek

**Trekari** · **02-04-08, 05:16 PM**

Here is what I am working with for my listening area and possible reflection points:

Would either of these products be useful in correcting some of the problems REW has pointed out? Note that I cannot place something of these sizes below the shelf but above the couch, they'd have to go ABOVE the shelf with the photos on it.

http://www.gikacoustics.com/gik_244.html

http://www.gikacoustics.com/gik_242.html

Or in order to be useful, would these products need to be placed on the ceiling?

**HClarkx** · **02-05-08, 07:25 PM**

Quote:

brucek wrote:

Full range speakers are in stereo, and create a soundfield. That's a big difference from a mono sub signal that is easily localized to a point source....

Good point.

Quote:

brucek wrote:

Or simply co-locate them, which is one of the better methods of running two subs. Find the best spot for one sub and co-locate the second to increase the headroom.

Also a good suggestion. THX reference is 105 db peak. Not many subs can do that in a room as large as Jason has (including kitchen and hallways). Also, you don't want to push the limits of a sub if you can avoid doing so. I have a 13,000+ cubic foot great room not including openings to kitchens and hallways and a large SPL-eating fireplace. My subs can each can do a theoretical 107 db at Xmax but I'm sure can't come close to 105 in that space. Hence I have four of them giving me theoretically another 12 db. That probably gets me close to 105 at the listening positions at Xmax. Because I found two good locations, I have two subs at each.

I'm sure Jason's neighbors would raise an eyebrow at this thread. I'm lucky, no neighbors.

Harrison

**HClarkx** · **02-05-08, 08:23 PM**

Quote:

Trekari wrote:

Would either of these products be useful in correcting some of the problems REW has pointed out? Note that I cannot place something of these sizes below the shelf but above the couch, they'd have to go ABOVE the shelf with the photos on it. Or in order to be useful, would these products need to be placed on the ceiling?

I'm not an expert at room treatment, but from what I've read, a pair of 2x4 panels might be a drop-in-the bucket for a room as large as yours. If you think about sound (below about 200 Hz) spilling out into the room and going in all directions, you realize that you have hundreds of square feet of reflective surface sharing that SPL. Hence a considerable number of such panels might be needed and would have to be optimally located. A good room treatment solution can require a lot of panels and a lot of work finding the right placement. Understanding reflections gives one a head start, but there's still a lot of trial and error to identify the right locations and the surface area required and the frequency response characteristics of the panels. The professionals use software to get a starting point, but still have some trial and error work to do. I can see it now ... Jason to wife .... "hold it a foot more to the left and hold another one alongside it and let me run another frequency scan...".

That said, a panel to quell the reflection off the back wall would definitely have to be centered right behind your head to be very effective.

Some of these panels on the ceiling strategically placed would also help. That placement could be estimated with the trigonometry you mentioned last week. A wild guess would be two panels on either side of the ridge.

I wouldn't give up on Audyssey and the BFD yet. They are a much more flexible and cost-effective solution. If they leave a significant problem or two that can be tied to a particular wall surface, then consider resorting to room treatment.

The price seems very good on these panels. Some are much more costly. I don't see any specs on them though I'm not sure there are standards by which to judge them in that industry.

Another thought occurs to me. One of Audyssey's strong points is that, while it can't fully smooth out huge peaks and dips, it can share what it can't smooth out fairly equally across the three seats. Tests at just one seat will tell you how well Audyssey can bring up a notch or shave a peak, but you really want to balance the notches and peaks (what's left of them) across the three seats. So, only a test with a full set of measurements will tell you the whole story.

Likewise, you don't want to be looking at just one seat when you work with room treatment. You want to consider all three and share the benefit.

The BFD as well needs to be set with all three seats in mind. If all three seats share the same notches and peaks, then you can improve all three quite well, but more likely there will be differences and you again will want to share the wealth. In a really bad stroke of luck, you will have a peak at one seat and a notch at another, both at the same frequency. All you can do with Audyssey or the BFD is balance them (10 db and 10 db rather than 15 db and 5 db). Room treatment probably has a better chance of addressing both, but only with a huge amount of work.

Harrison

**Trekari** · **02-05-08, 10:39 PM**

If I had a wife, I wouldn't have the money to blow on my sound system

Really though, I think I've reached a point where I'm going to break in a few new speakers (pics coming by Friday I'm thinking), run Audyssey with 8 measurements, set the BFD to create a house curve and call it good.

If room treatment was easier, or if my room would respond better to select treatments that don't include coating every possible reflection point, then I'd go that route.

But hey, at some point you have to just call it good and save the really expensive and time-consuming projects for a dedicated room.

**HClarkx** · **02-05-08, 11:56 PM**

Quote:

Trekari wrote:

But hey, at some point you have to just call it good and save the really expensive and time-consuming projects for a dedicated room.

Yes, one can go nuts/overboard to little avail.

If you use REW again after you are all tuned up, don't sweat the narrow peaks and notches (mostly notches) .... unless they are horrendous (wide and deep), it's unlikely fixing them will improve the sound much. Better to spend the time listening than trying to fix a minor issue.

Please do try your tone control. Even with a 50 Hz center, it may have a low enough Q to provide a nice adjustable, remote-controlled loudness control. A base line and +6db bass boost REW recording will tell you what your bass tone control does for you (though your ears will tell you more ... whether you like it). It's an underutilized feature these days, especially for movies.

A second use of the BFD could be for loudness. If you watch movies at typical home listening levels (about 85 db peak) you want an "equal loudness" boost to make a movie sound, at 85 db, like it does at 105 db reference level. I.e., to compensate for your ear/brain's loss of sensitivity as volume is reduced. There are adjustments for mid and high frequencies, but the low end is what most people notice.

frequency/db
20/6
30/5
40/4.5
50/3
60/2
70/2
80/2
90/1
100/0

This will make movies at home sound like they do in the theater without irritating the neighbors by playing at 105db.

Enjoy.

Harrison

**Trekari** · **02-08-08, 09:25 PM**

New look

**HClarkx** · **02-08-08, 10:45 PM**

Really really nice. In my wife's dreams mine would look so good. My subs (home made) have black grille cloth draped over the unfinished wood boxes.

Your center is very close to your mains in capability. That's rare and very good.

My center sits on a table as well. Though that's not necessarily problematic, I hope to move my components off to the side and put my center on a shelf under the TV so it has free air around it like the mains.

Your center and mains look to have enough woofer capacity to support an 80 Hz crossover (and that was confirmed by your REW tests). Or 120 if your prefer.

Enjoy.

Harrison

**Trekari** · **02-27-08, 12:24 AM**

Sorry for the long absence - been doing some remodeling of the home.

The Center channel (and indeed all of the surround speakers you see) are completely sealed around the back.

Coming up soon, I happen to finally have enough of an RCA cable I believe to do testing without moving my PC to the living room. I was hoping to wait until the next version of REW came out, but that seems to be a bit stalled.

As for my FEQ2496, I plan on using that to calibrate a flat response from the subwoofers, and THEN running Audyssey. The reason for that is when using my analog multichannel inputs, the Onkyo 705 doesn't do any processing of that audio. (No Audyssey, no crossovers, nothing) My recent adventure into surround sound music means that if I do the 2496 *first*, and then run Audyssey...whenever Audyssey is not able to be used (SACD playback, DVD-A, etc through the analog inputs), then I still have flat bass response.

Does anyone have suggestions on a house curve for multichannel music?

**HClarkx** · **02-27-08, 01:07 AM**

Quote:

Trekari wrote:

Does anyone have suggestions on a house curve for multichannel music?

I can't help you with the house curve other than to suggest starting with flat and use your tone control to deviate from that and then pick a curve that kind of matches what you found desirable with the tone control. Or just try each one. Does the Onkyo let you try the different curves without completing the setup as the Sound EQ Pro does?

I suspect that your speakers, your room acoustics, the music you listen to, and your hearing might all influence the house curve you choose. I include speakers and room acoustics in the list because Audyssey doesn't 100% eliminate them from the equation.

Harrison

**Trekari** · **02-27-08, 01:22 AM**

No, the Onkyo doesn't allow you to give trial listens to the curve. And in the EQ section, your only options are "Off, Manual 7-Band, or Audyssey."

On another note, I'm quite happy with how my room turned out. I think moving the couch forward gave enough room for the Surround Back speakers to work well.

**HClarkx** · **02-27-08, 01:33 AM**

Quote:

Trekari wrote:

On another note, I'm quite happy with how my room turned out. I think moving the couch forward gave enough room for the Surround Back speakers to work well.

The room is very nice. I like it. I'd stuff a couple of throw pillows into the new bookshelf behind the sofa (right behind your head) when I'm doing serious listening. But then the question is whether to have them there or not when doing the BFD and/or Audyssey setup?

Harrison

**Wayne A. Pflughaupt** · **02-27-08, 09:20 PM**

Nice looking room, Trekari!

Re the house curve, never really thought about what it would take to do it with multi-channel. I’d say determine your needed slope with the usual method, but the tricky part might be blending with the mains. Offhand I’d say you might need to run the sub (EQ’d for a house curve, natch) a bit hotter than you would normally, since extra speakers are operating. On the other hand, it could be that the extra speakers running might make you inclined to run your overall volume levels a bit lower than usual, which would put you back where you started. Probably Harrison’s advice is best: Listen and let your ears decide.

Regards,
Wayne

**Trekari** · **02-27-08, 11:55 PM**

Well, the BFD/Audyssey interaction came to a head last night while I listened to a SACD through my analog multichannel inputs on my Onkyo 705. Those inputs get no processing whatsoever and the high frequencies nearly drove me insane.

So

rather than use the Burr-Brown DACs in the upcoming Oppo 983 I wish to purchase, I will relagate myself to using HDMI PCM so that Audyssey can be applied and those ear-piercing high frequencies can be quelled.

I mean seriously, it was downright painful to try and listen to. I suppose room treatment would fix that problem, but for now I've got many long months of plasma donating to pay off what I've done thus far

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