Jbl bassq

I just installed BassQ in my home theater last week. In short--it works. My room has 2 rows of 3 seats, and there was a large difference between the various seats, particularly between the rows. I have yet to install bass traps, and while I'm sure they will help (they are now on order), they would not solve the problem as well as BassQ + traps, I'm certain.

I did not want to buy several subs, so to test the BassQ theory, I first tried using the speakers I already have. The room modes are between 35 and 120 Hz in my room (11.5' x 17' x 8'), and the main L/R speakers and 4 surrounds each cover down to 30 Hz nicely. That's 6 mid-bass "subs" in effect, and then I also have a separate powered sub that goes <20Hz. Figured I had enough bass drive capability.

So I am crossing over all speakers at 100 Hz [update: 80 Hz] in the AV processor, and I tell it there's one Sub. Now I have one audio signal carrying all the bass. I feed it into the BassQ box. The 4 outputs are then distributed to the L/R and 4 surrounds (driving the Ls/Lb with one signal, and Rs/Rb with another, thus sharing the load). The front L/R are more capable speakers.

The diagram shows the signal path of the bass management system I'm using. It anticipates the use of an SSP-800 which has 2 sub outputs, but for now my processor has one sub out, so I use a Y splitter to drive the two paths. The resistor summers are in an aluminum box I made. Works great.

I also just received the XTZ Room Analyzer kit which helps see the before/after effect. The plots show blu and white curves. The blu are the measured results. The white show how it would look if the suggested PEQ filters were added.

Fig 1 shows the use of only the 4 "corner" speakers used as subs. The Ls/Rs are not running. The "front" graphs show the XTZ mic moved to 3 positions across the front row. The "rear" graphs show the same for the rear row of seats. You can see from Fig1 that BassQ helps make the two rows look more uniform.


I then added the Ls/Rs in parallel with the rears, and re-ran BassQ setup. The results are in Fig2.

These plots also show that the speakers all roll off below 25 Hz. So I added a bit of a high-pass filter from an analog Rane EQ to cut off below 30 Hz, and I added my main sub with a 30Hz LPF. I did not re-run BassQ, as the main sub is not in the BassQ signal path. Fig 3 shows the overall results.


Fig3 is what I'm listening to, and it sounds very good already. My room still has ringing at 80 Hz, causing a notch in the rear seats, so the bass traps ought to help knock that down. For ref, here's my room layout with the mic positions added:



I hope to hear from you or others who give BassQ a try.

Roger how much is retail on the BassQ and where do you get one?

Retail is $1200. Use the JBL dealer finder. Scroll down to "By Series" and select "Performance Series" as that's its family. Good luck!

If the link is broken, Google JBL Synthesis.

thx

So Roger, how are those additional faux "subwoofers" working out? Do you like the sound quality? How flat did you get the bass? Plus or minus how many dB?

I still have my single speaker overlap "MBM" running in my system, and my FR seems to measure reasonably flat considering no EQ being used.

I very much like the sound I'm getting in my room. However, I cannot play movies above -15 dB wrt ref, as strain sets in on the major bangs, and that's not a problem for me. I have not yet implemented a proper high-pass for the mains and a separate low-pass for the ULF path. I'm discussing that with the SSP maker. That may help the headroom a little, as the mains are being fed full range at the moment.

I suppose having 2/4 more real subs would rock the place, but I'm not motivated to do that.

Since my post about BassQ I have replaced the Tag McLaren AVP with an SSP-800, and that has had an unexpectedly beneficial effect on the clarity of the system. Didn't appear to change the bass, though. (I just wanted access to HDMI audio from BD.) Also added some bass traps. Can't say they made a huge difference, though. Between the BassQ and the SSP, the system was transformed from what it was when first fired up.

Flat? Nope, I don't tune for flat, as I listen to music/movies 15-20 dB below mix level, and I like hearing the bottom octave without bass bloat. I'm an Arnie Nudell/Cary Christie disciple, I guess.

I run my mains as large, but they are sealed. I use Dolby BM configuration 2, and my subwoofer just fills in as the mains roll off near 50 Hz. No problems playing WOTW DTS at -6 dB from reference level, but that is a bit too loud for my taste.

My overlap "MBM" runs a bit higher in frequency than your setup. I needed to cleanup dips in the mid and upper bass more than just the mid bass frequencies, so I am more in line with the Geddes objectives. I LP filter the MBM up near 160 Hz, and you are more in the 100 Hz area.

I suppose a picture is worth a thousand words, so here is a picture of the results of my JPC MBM addition. The upper FR waterfall show the FR with the overlap MBM activated, and the lower part of the waterfall shows the FR of only the L & R mains plus the subwoofer run as a set. The MBM clears up mid and upper bass quite a bit. Fairly flat FR, but I measured after I set the volume levels by SPL meter and by ear.

WTW!


At the moment I have the bass crossover set for 80 Hz. I have not yet checked to see what happens when shifting that to higher frequencies. In my case all the subs run pure mono, so I didn't want to narrow the spatial effect by going much higher. I believe you run yours in stereo groups, so can avoid that limitation. I'm also wondering about having mid-freq bass coming from the rear of the room, where rear-seated folks might pick up on it. Currently, it's easy to hear the midbass coming from the rear speakers when I walk right next to them, but in the seats it's not noticable. I'm not sure how much higher I could go with the crossover and not cause imaging/pulling problems. I guess I should try it!


Flat in deed. A thing of beauty. You may have said before--but how was thos plot made--single point, average of several, weighted to any one position, filter BW?

Some sample WOTW waterfall measurements were made a short while back. Playback levels are given with each waterfal, but -10 dB from reference level is not bad for WOTW DTS.

Comparison of simultaneous electrical signal and in room speaker waterfalls of various scenes of WOTW are shown in the following thread. Some Apollo-13, Transformers and Incredible Hulk scenes also. That comparison was kind of fun to do. Kind of interesting to see how close the electrical and acoustic responses are for various scenes.

Start at page 11 to get a feel for the discussion about Spectrum Lab waterfalls.


http://www.avsforum.com/avs-vb/showt...163329&page=11






We are working a different part of the modal area. You probably are familiar with all of this, but I was not familiar with the difference between modal acoustics and geometric acoustics before that Geddes thread. The Schroeder frequency divides the two areas. For small rooms this frequency is around the 150 Hz area depending of the room. Section 4.1.b for reference.


http://www.gedlee.com/downloads/Chapter%204.pdf


The major problem with room modes in my room is not in area that you are working with your setup (below 80 Hz). Geddes suggested that the modal area that needs work in all small rooms is between 50 Hz to about the 150 Hz or so area.

Geddes and HSU recommend a VLF subwoofer in a single location with a crossover around 50 Hz or so. That is the subwoofer crossover frequency area that I have settled on over the years, but HSU and Geddes put some detail in why that is a good subwoofer frequency.

HSU and Geddes try to work the 50 to 150 hz modal area by different means. That is the same frequency area that I am working on. I don't think the exact method of working this frequency area makes a huge difference, but I do think that you have to work up to the 150 Hz area (plus or minus).

I you get the basic concept, then you can try many different technical tricks to deal with the problem frequency area that applies to your own specific room.





Each color covers about a 6 dB signal level. My main seating area is better than I expected to see when I made that measurement. That Spectrum Lab program is way cool once you figure out how to work it.

The Spectrum Lab waterfall plot is very informative but the options are very restrictive. One or two locations at a time can be waterfalled, but no averages or smoothing. You can do a bit of smoothing between adjacent bins, but that is about it.

However, if you move the microphone around you can see changes in the waterfall. In the past I have made a seating area waterfall by moving the microphone in a football type of shape (up, down, forward, back). I then slowly shift the microphone left to right in the seating area. The waterfall then shows a spatial average over the area that you swept the microphone over. Kind of a cool measurement tool when you get right down to it.

Roger,

Thanks for taking the time for writing this review.
I am in a similar smallish room and am seriously considering the BassQ to spatially even out my response. My RT60 (200hz+) is already way too low and can't afford to add more broadband absorbers. Wood Bass panels are out of question as well(WAF...).

Any updates on your system?

No big news. It's all running well. I did add some ASC Tube Traps and did not notice any reduction in the 80 Hz room resonance tails where I sit--although muddiness near the speakers seems less (but I don't sit there). My PEQ will soon be fixed so I'll reinstate some notch filters that XTZ prescribed.

Just to make sure this will work for you, BassQ needs at least 2 subs (ok for a single seat or single row), but can cover more area with 3 or 4 subs. Will you have multiple subs?

There was a meet at the Harman facility recently, and the advice they gave was to start with 2 or 4 subs, and even without special electronics it will make a real improvement (assuming the room and positioning are all working cooperatively).

Hi Roger,

Thanks for the link in the R-972 thread to the fascinating chat with Floyd Toole http://twit.tv/htg14 .

I'm getting a bad feeling about the BassQ still being available to consumers, as most of the links from turned up by a search are dead ends.

May I ask where you got yours?

Thanks

Noah..
As I posted many months back for Harman/Kardon and JBL multiple subwoofers have been strongly pushed by Dr.Toole & his R&D team including Todd Welti for the last 7 years. However note that Floyd has retired but is still a consultant to Harman International and his primary tasks of R&D have been taken over by Dr. Sean Olive who posts here from time to time. Floyd and Sean have worked together for many years, so Sean is now driving this R&D effort not just for Harman Consumer but also Pro and OE groups. We have taken several courses of Dr.Toole over the last several years and strongly recommend his book if you don't have it. Here is link for your reference..

http://www.amazon.com/s/ref=nb_sb_ss...ix=Floyd+toole


All of Harman Specialist brands' are now centralized under JBL Pro and controlled by Crown in Elkhart, Indiana. These brands includes Lexicon, Revel, JBL Synthesis and Crown, note that AudioAccess brand, inventory and IP has been sold off to ATI.

The JBL BassEQ component is part of the JBL Synthesis lineup, and available through their distribution. Below is a link to its respective webpage.

http://www.jblsynthesis.com/products...=US&Region=USA

Note that they also have an attractive product accomodation program, if you know somebody in the custom install biz or inside of Harman International..

Just my $0.01..

Direct from Harman--some good friends there cleared the way for me. I admit I never tried contacting the regional Synthesis reps, as at that time, it was marketed under "Performance Series."

Dr. Toole mentioned to me yesterday that the BassQ unit is/was aimed at the mass market (user install), while Synthesis is custom install. I commented that if he could do anything to help encourage Harman to improve its visibility in the market, it would probably sell well.

It would be great if they can lower the price a bit & make it available for consumer sales. Looking at the manual it seems very easy to use.

Got a link to the manual?

Noah..

Send an email to todd.packer@harman.com
Todd was the product manager for the brand and should be able to supply more technical info.

Just my $0.01..

Link to the JBL BassQ manual.

Thanks, M Code, I'll try that.

Ah, it works in IE but not Firefox.

I wonder if they would respond differently if you called them on the phone. Might be worth a try.

I will give it a try.

Randy,

I don't know where you are or whether JBL restricts by region, but I want one so maybe a double sale will help their motivation.

I am in KC MO

Does BassQ do any sub equalization? Just wondering how it actually works.

Short answer: Yes.
Long answer, see the Harman patent application attached.

 

BassQ patent.pdf 220.5146484375k . file

On my old cell phone, I have a number for a local source that was willing to sell me the BassQ. If anyone is interested, PM me, and maybe we can try to work something out?

Contacted a friend who is an installer.....looks like he has access to this unit....may be getting one
I think it may be a good addition to my 4 HSU Research ULS15's

RayJr

Should have my BassQ box next week
I will see if I can ad a little more input to this thread.

RayJr

Just got my Bass Q...I should have time to try it this weekend.
Think I will invite Sdurani over to give me a hand...and hopefully more input on this unit.

More info to come

RayJr