[rmurray]

 Speaker size question. Recently moved . My listening space has reduced  and I am finding my JBL 12 inch drivers possibly too much energy for the 10 X 14 foot space. All thing equal to my former set up the bass is now way out of proportion. Would going to a smaller scale speaker help. I'm thinking that an 8 inch bass driver would be a better choice, like the MINI T perhaps.     

[undertow]

Not sure this is the circle for the question, but a 10ft x 14ft is on the smallish side of room size you are correct.

However, I would think normally a 10" to 12" size woofer is a reasonable on average for that still. Specifically if it is passive vs. active. In other words looks like you are not using a subwoofer.  I have had 15" in a 13 ft, x 15ft room with exceptional results. I don't honestly know how much your current speakers are worth so figuring out if its worth selling, and investing in a new pair would also be a question. Not knowing what model JBL it is does not help much. Efficiency, frequency response etc... will all come into play when determining a course of action.

I would look into possible Bass traps, like the ones from GIK acoustics, or others that can help you tame the bass bloat for a few hundred bucks. Normally they fit in corners, and with a room that small it would be beneficial overall anyway with any speaker you use. The bigger the room the less acoustic treatment normally it needs, so your on the boarder line of being in an average sized room. Room setup, and positioning are all key to getting the results you seek. Again downsizing to a small monitor or something could help, but at what cost vs. simply trying to accommodate your current setup?

Also, if you have any space to experiment with positioning of the speaker it helps. Spreading them further apart, or closer, further from the wall and corners etc... Toe in and Toe out also can help considerably depending on the acoustic situation in circumstances like this. In anycase if you like the speakers I would highly suggest some other routes of experimentation before dumping a more capable 12" for a limited response woofer that will likely not have the output, or depth in response you are accustom to.

[rmurray]

Not sure this is the circle for the question, but a 10ft x 14ft is on the smallish side of room size you are correct.

However, I would think normally a 10" to 12" size woofer is a reasonable on average for that still. Specifically if it is passive vs. active. In other words looks like you are not using a subwoofer.  I have had 15" in a 13 ft, x 15ft room with exceptional results. I don't honestly know how much your current speakers are worth so figuring out if its worth selling, and investing in a new pair would also be a question. Not knowing what model JBL it is does not help much. Efficiency, frequency response etc... will all come into play when determining a course of action.

I would look into possible Bass traps, like the ones from GIK acoustics, or others that can help you tame the bass bloat for a few hundred bucks. Normally they fit in corners, and with a room that small it would be beneficial overall anyway with any speaker you use. The bigger the room the less acoustic treatment normally it needs, so your on the boarder line of being in an average sized room. Room setup, and positioning are all key to getting the results you seek. Again downsizing to a small monitor or something could help, but at what cost vs. simply trying to accommodate your current setup?

Also, if you have any space to experiment with positioning of the speaker it helps. Spreading them further apart, or closer, further from the wall and corners etc... Toe in and Toe out also can help considerably depending on the acoustic situation in circumstances like this. In anycase if you like the speakers I would highly suggest some other routes of experimentation before dumping a more capable 12" for a limited response woofer that will likely not have the output, or depth in response you are accustom to.  Thank you for your view on this , really appreciate it.

[redbook]

 Now this could be a place where a graphic equalizer would be a key tool for recordings that may be bass rich.

[rmurray]

 My amp is a 4B ST. It is said that the newer designs (SST ) have been more base refined as well as smoother over all. Perhaps a newer amp will help me  at this point too :

[undertow]

Hmm.. Well honestly changing an amp to "Reduce" bass output is probably not the best way to look at it. Generally damping factor could help tighten bass up, but I assume the Bryston has a pretty high damping factor already. I could be wrong. Your issue is purely acoustic because you already know that the system works well in other sized rooms. So changing that formula brings other issues likely you will find after trying to create a new synergy in equipment. I would focus on the room, and setup first.

Isolating the speaker cabinets also can help. If they are ported, and your firing them directly into corners this will also cause a bigger bloated bass note to carry, and get annoying. A lot of other factors will come into play for experimentation before tossing your amp or speakers.

If you have the itch the best way to try a new amp is to go borrow one first from a local shop that can be returned, and find out if it moves the needle at all toward the results you expect in doing something like that is my suggestion.

[richidoo]

rmurray, the room acoustic boosts bass with a slope of +12dB/octave. The frequency at which the boosting starts is proportional to the volume of the room. Sealed woofers rolloff at -12dB/oct, the frequency at which they start rolling off is inversely proportional to the woofer cone area. So you can see that there is the potential of matching the woofer size to the room size to give a flat bass response. 12" woofer is probably too big, but it's worth a try to plug up the reflex ports of your speakers to see how well their natural rolloff (when sealed) matches the room's boost. A reflex port extends the flat frequency response lower than sealed, but then rolls off very fast, so the reflex ports could be exacerbating your problem. Plugging the ports to make sealed woofers will improve their transient response and phase response, so it could sound clearer, depending on room acoustics, speaker placement. You might be accustomed to the fat sound of ported speakers and switching to sealed might sound too lean in a big room. But if your small room's boost adds only a little more than the woofer's rolloff subtracts then it could make the bass sound nicely fat in the midbass without too much low bass from the port.

Pulling the speakers away from the wall can reduce the feeling of too much bass, to a degree, but in a small room it can be hard to get them far enough away to notice the difference.

If you already have sealed speakers, or if plugging the ports is not enough bass reduction, then you can apply a simple first order, passive, line level EQ filter to trim down the bass signal electronically. All you need is a single cap and resistor (per channel.) Make a short interconnect extension cable to install between preamp and power amp, with alligator clips installed in the cable to allow clipping in different size caps and resistors until you find the right bass rolloff you are seeking. You can use some good sounding but inexpensive caps like Vishay 1813 to find the filter frequency you like, then solder in a nice teflon cap later if you want. The filter parts are small so you could install it into the RCA plug of your regular IC, or make a short IC extension of very high quality.

Here's details for building the filter.
http://www.t-linespeakers.org/tech/filters/passiveHLxo.html
R(amp) is the input impedance of your power amplifier.  A simple analog filter like this is much cheaper ($20) and much higher fidelity than any box you can insert into the signal path.

There are also commercial line level filters like this that you can buy. Car audio guys (with big woofers and small room volume) use them to make this exact adjustment. Can't remember the brand name tho... anyone?

If you don't like your current speakers, then this may be the perfect opportunity to go speaker shopping!   
Rich

[rmurray]

 Thanks Richidoo for those ideas. I thought there may be ways to filter down bass response but never knew how I  may talk to those car audio people.

[rmurray]

Hmm.. Well honestly changing an amp to "Reduce" bass output is probably not the best way to look at it. Generally damping factor could help tighten bass up, but I assume the Bryston has a pretty high damping factor already. I could be wrong. Your issue is purely acoustic because you already know that the system works well in other sized rooms. So changing that formula brings other issues likely you will find after trying to create a new synergy in equipment. I would focus on the room, and setup first.

Isolating the speaker cabinets also can help. If they are ported, and your firing them directly into corners this will also cause a bigger bloated bass note to carry, and get annoying. A lot of other factors will come into play for experimentation before tossing your amp or speakers.

If you have the itch the best way to try a new amp is to go borrow one first from a local shop that can be returned, and find out if it moves the needle at all toward the results you expect in doing something like that is my suggestion.

[*Scotty*]

rmurray, depending on where you are sitting in the room you may be in the middle of a massive standing wave zone which could easily be boosting the bass as much as 20dB in a specific location at certain frequencies. Likewise a null of potentially the same magnitude at a different frequency could also exist a foot away from the same location.
It's a cinch that you will find it difficult to find a sweet spot where the bass is acceptable without a great deal of experimentation and possibly purchasing a different loudspeaker.
 Which JBL loudspeaker do you have? Richidoo has a good idea about plugging the port if the speakers are a vented design. I hope you can find a solution that does not involve too much financial pain.
Scotty
Scotty

[rmurray]

Thanks Scotty. I have the Ti 120s circa....1988... These babies have kept pace with all  my electronic upgrades over those years. They seem to have great synergy with my 4B st and BP25 : : :

[rmurray]

going to plug the ports tomorrow when my neighbors are gone

[redbook]

 This could perhaps cure that room acoustic issue....

[DaveC113]

rmurray, depending on where you are sitting in the room you may be in the middle of a massive standing wave zone which could easily be boosting the bass as much as 20dB in a specific location at certain frequencies. Likewise a null of potentially the same magnitude at a different frequency could also exist a foot away from the same location.
It's a cinch that you will find it difficult to find a sweet spot where the bass is acceptable without a great deal of experimentation and possibly purchasing a different loudspeaker.
 Which JBL loudspeaker do you have? Richidoo has a good idea about plugging the port if the speakers are a vented design. I hope you can find a solution that does not involve too much financial pain.
Scotty
Scotty

+1, Placement is often the culprit, try different speaker arrangements. Asymmetric or offset setups can often help a lot. I think it's likely you can solve your problem just by moving the speakers around. I do not think 12" woofers are too big, it's more to do with cabinet tuning and the fact that that big woofers can often play lower. When people say they feel the room is being overloaded I think it's usually modal issues.

Plugging the ports might be worth trying but you'll also have more excursion so if you play loud be careful. If you have 2 ports try just blocking one of them, this will lower the tuning frequency which will cause the bass to roll off earlier and lowers the port area, which reduces the port's contribution. If you do seal teh cab it would probably be ideal to also add a bunch of stuffing if the bass needs to be damped more, which is likely because of the additional excursion.

EQ can help for sure, but don't try it until you get the modal issues under control.

[Yitshak]

Speaker size question. Recently moved . My listening space has reduced  and I am finding my JBL 12 inch drivers possibly too much energy for the 10 X 14 foot space. All thing equal to my former set up the bass is now way out of proportion. Would going to a smaller scale speaker help. I'm thinking that an 8 inch bass driver would be a better choice, like the MINI T perhaps. 

I wouldn't regard the better choice as I never heard your specific speakers yet I heard other
12" in the past.

In regard to the Mini T's maybe I can shade some experience:

I have two setups of Mini T's
Both powerd by 4Bsst2's.

one in a room bigger then yours of 12' X 15' and at places 21' (asymmetric) that soon the 21'
will get symmetric do to change we going to made.

The other one is in room 9' X 12' smaller then yours.

Now come the nice thing,
the Mini T's perform equal well on both setups!

I found the Mini T's the most versatile speaker I have ever encountered.
With a bit of toying one way  or the other they sound as 12" better then any speaker
I can think of or heard in such small size relatively (if we excludes those like TAD babies as they are not competitors in price or any Other brand for this matter).

And with the same toying approach they play marvelous in the smaller room.

So Room Modal and placement and acoustic treatments do play major
But as I expiriance for my self the Mini T's are easy to overcome some of those.

I liked BIG old school 3 ways 12" monitors all my life (and I still think they are the only way)
But to my luck I discovered that the Mini T's fit the 12" Monitors bill
better then any other for me.

So bottom line
in regard to your amp they work a charm for me in both sized rooms.


Cheers

Itshak

[Yitshak]

Maybe I should've add:

To my suspect what contribute a lot to the less room modal issues with the Mini T's
Is the unique chosen lower cross over point 160hz!

This way all spectrum down to true bass perform by the 5.25" and Twitter as a mini monitor
And the "big wheel" raise up for the artillery only

Yet this 5.25" driver is no light weight in any way as when volume knob turn
up,its raise to task and keep integration with the 8" driver as one.



Itshak

[James Tanner]

Hi Folks,

Well you left me an opening here to spout my philosophy on speakers and room interfaces - LOL

BRYSTON
Listening Rooms and Sound Power

BACKGROUND:
The two most critical parts of any loudspeaker system choice is the listening ‘ROOM’ and the loudspeakers ‘POLAR’ response. Recognizing how the room imposes its boundaries (floor, ceiling, walls) on the speaker and how that speaker radiates its energy (polar response) into a specific room is critical to the understanding of the overall performance of any speaker and it is no different for the Bryston loudspeakers.

When you are listening to a loudspeaker in a room you are always listening to a balance between the ‘Direct Sound’ and the ‘Reflected Sound’ from the boundaries of the room – this is called the ‘Power Response or Sound Power.’ It is that balance between direct and reflected energy which changes depending on the frequency radiation pattern (polar response) of the given speaker and the boundaries of the room the speaker is placed in. Dipoles, Bipolar, Omnipoles, Direct Radiators, Horns etc. all behave differently due to their specific radiation patterns and therefore exhibit different power responses in any specific room. Bryston has chosen a direct radiator approach in the design of our loudspeakers for numerous reasons but one critical reason is because we feel it is currently the best way to accomplish the correct balance between direct and reflected energy in real world listening rooms.

DIRECT and RELECTED SOUND:
The ‘direct sound’ is the sound radiating from the front of the loudspeaker and the ‘reflected sound’ is all the sound your ears perceive after the sound waves have interacted with all the different boundaries in the room. It is important given real world conditions that the on axis response and the off axis frequency response of a loudspeaker be as uniform as possible. This on and off axis characteristic is generally referred to as Polar response. The smoother and more uniform the on and off axis polar response of the speaker the better the tonal balance between the direct sound and the reflected sound will be. In other words, the reflected sound will have the same overall tonal balance and sonic characteristics as the direct sound if ‘on and off’ polar response is smooth and even. This approach also provides the optimum overall 3-dimensional soundstage presentation as well. The Bryston loudspeakers are a very wide dispersion design so the polar response is very flat on axis and very uniform all the way out to more than 45 degrees off axis in both directions from center to provide a very wide and even listening window.

LISTENING WINDOW and SOUND POWER:
In a loudspeaker the ‘listening window’ is an average of a front set of curves whereas the ‘sound power response’ is an average of all the curves right around the whole speaker.  What we actually hear is heavily weighted to be a balance between these two conditions.  The listening windows frequency response should be very linear (flat) across the entire audio band but the sound power should fall off by 8 – 10dB by the time you get to 10kHz (see diagram below) while still remaining linear in its march down from the bass frequencies.

Striking the proper balance between these two is extremely important to the sound of the speaker.  Keeping the listening window and the sound power both linear is not an easy task and is where most speakers fall down. 



Typical Model-T Passive Anechoic Response

Typically there is a lot of attention paid to the linearity of the direct on-axis frequency response by reviewers and knowledgeable consumers but it is really just one curve in the mix of 300 curves Bryston utilized in the design of our loudspeakers. 



DYNAMIC COMPRESSION

Another area that is very important with loudspeakers is a lack of dynamic compression. Dynamic compression or the inability to maintain composure under high playback levels plagues many loudspeakers. Brystons’ astonishing lack of compression brings a lifelike realism to dynamic events in music and movie soundtracks without introducing artifacts that might disrupt your enjoyment.

At left, note that the frequency response of our Bryston Model T speaker at a punishing 110dB is virtually identical to that of the speaker at a more common level of 90dB. 

With most speakers you will see the frequency response start to suffer as volume levels increase. Not with Bryston speakers - this is astonishing performance regardless of price.

[James Tanner]

Also now that I have the opening here is some info on the driver development that went into the Bryston speakers.

BRYSTON SPEAKERS:
CABINET AND DRIVER DEVELOPMENT

Question:

James what part did loudspeaker drivers and cabinet design play in the development of the Bryston speakers?

Answer:

I guess the best way to explain the Bryston Model T speaker is we did not really start with a specific driver design in mind.  We started with the Bryston reference speaker concept and the speaker concept determined what type of cabinet and what kind of drivers were needed. 

The above is the main motivation for why I went to a specialized company driver and cabinet  manufacturer in the first place as I knew needed someone with the qualifications and capabilities to design and manufacture a speaker from the ground up - (anechoic chamber, sophisticated test gear, excellent engineering talent, 30 years of experience in speaker design, ability to design and build custom drivers etc.)

So once I decided I wanted a full-range speaker with extremely low distortion, wide power response, wide listening window with high power handling and no dynamic compression the project moved in that direction. So the Model T cabinet was designed and the compliment of drivers and cabinets we went through involved about 5 different iterations from (single woofer – single mid – single tweeter) to what you see now – (Triple Woofers, Dual Midranges and Dual Tweeters). 

All our goals were met with the driver and cabinet compliment you see now in the Model T and the cabinet bracing and driver design is a function of what it took to reach that goal. With the additions of the other Bryston Speaker models - (mini t, Middle T, Center channel, Subwoofer, On-Walls and In-Walls etc.) different drivers with different characteristics and parameters (voice coil type, magnetic structure, suspension system, compliance etc.) were developed to optimize their performance in each specific cabinet. 

Hope this helps

James
Bryston

[rmurray]

 Thanks to everyone for the good advice and guidance 

[servingko]

James, so there are different versions of the mids and woofers between models, but are the tweeters the same across the models?