OK, this isn't a question about what effects the size of the box has on the overall response of the driver.
Rather what effect when listening is the effect of having two two different "sub-woofers" handling the same pass-band i.e: frequencies below 120Hz, but with different drivers with different "Qtc"
I just finished rebuilding the Kicker box and I want to utilize a big Cerwin Vega woofer i have sitting on the shelf, if I make a box of 120 liters it will be almost critically damped and have a "Qtc" of about 0.57.
I do not have the WAF to built the big TL that this driver deserves so I have to build as small as possible, NO 3 meter towers in the corner.
So I will have the Kicker with a warm "Q" of 0.85 and the Cerwin Vega with "Q" of 0.57
Is this good or bad? or will the room totally over-ride these differences??
Rather what effect when listening is the effect of having two two different "sub-woofers" handling the same pass-band i.e: frequencies below 120Hz, but with different drivers with different "Qtc"
I just finished rebuilding the Kicker box and I want to utilize a big Cerwin Vega woofer i have sitting on the shelf, if I make a box of 120 liters it will be almost critically damped and have a "Qtc" of about 0.57.
I do not have the WAF to built the big TL that this driver deserves so I have to build as small as possible, NO 3 meter towers in the corner.
So I will have the Kicker with a warm "Q" of 0.85 and the Cerwin Vega with "Q" of 0.57
Is this good or bad? or will the room totally over-ride these differences??
What???
No opinions from any-one??
Well then; I guess I'll spend a few dollars on chipboard and make a full size test box and listen for a few days.
it is a very small room5M * 4.5M and not the best shape and the Kicker box when EQ'd gives a rich bottom end, one both of us can live with ( which is important ) the main problem that I can see is having the amp clip when driving the CV
No opinions from any-one??
Well then; I guess I'll spend a few dollars on chipboard and make a full size test box and listen for a few days.
it is a very small room5M * 4.5M and not the best shape and the Kicker box when EQ'd gives a rich bottom end, one both of us can live with ( which is important ) the main problem that I can see is having the amp clip when driving the CV
Moondog55 said:
Yes! And this is the reason why sealed box Q factor does not have a great effect on sound quality. Forget talk about sloppy bass, tight bass etc. usually associated with small differences in Q (say ~0.6 vs ~0.9). The room mode Q factors are certainly much much higher.
There are other considerations though. Too small box may roll off the bass too early and may be a problem if you can't equalize it back. And even EQing is problematic because of the reduced efficiency of small box and much higher power requirements.
OK thanks, just confirming what my thoughts were.
The 120 litres is a big box for this particular driver
The 120 litres is a big box for this particular driver
Don't know anything about the drivers but I do know that the phase / group delay will be different on each driver which won't help..
How about using a big EBS type vented enclosure for 1 driver down low and cross it to a Linkwitz transformed small box for the other one ? Xo around the 30Hz mark. Uses both drivers and when the home theater EBS is kicking out the huge rumbles the LT box will still be unstressed and 'tight'
Rob.
How about using a big EBS type vented enclosure for 1 driver down low and cross it to a Linkwitz transformed small box for the other one ? Xo around the 30Hz mark. Uses both drivers and when the home theater EBS is kicking out the huge rumbles the LT box will still be unstressed and 'tight'
Rob.
Hadn't thought too much about group delay and phase.
From that POV maybe I should use a smaller box for the CV but chip board is cheap enough.
LT is a brute force solution that reqires amplifier power I don't have at the moment but it has been in the back of my mind
From that POV maybe I should use a smaller box for the CV but chip board is cheap enough.
LT is a brute force solution that reqires amplifier power I don't have at the moment but it has been in the back of my mind
Regarding phase/group delay, again the room dominates. By having the other subwoofer even a short distance from the other yields much larger difference than between the subs. What we hear is the total response, there is no 'direct sound' at low frequencies.
Moondog55 said:
I'd say it doesn't matter much as long as they are fairly close together and they are receiving the same signal. If one is "Left" and the other "right" you could have symmetry/imaging issues depending on where they are crossed over.
What happens if the x-max is different, or there are vast differences in the response at high power levels ? one driver could be distorting or hitting its end stops whilst the other isn't. - What would that do to the other drivers response ?
I've read many times that a drivers parameters will vary with heat on the voice coil. This would put other differences into the equation...
Anyway maybe I should have typed " Personally I'd prefer to run like for like drivers in my system " It was opinions he asked for and you know what they say about those 😉 😀
Cheers,
Rob.
I've read many times that a drivers parameters will vary with heat on the voice coil. This would put other differences into the equation...
Anyway maybe I should have typed " Personally I'd prefer to run like for like drivers in my system " It was opinions he asked for and you know what they say about those 😉 😀
Cheers,
Rob.
Totally agree with breez (and glad to see someone with the same rational view point 😀
Any way. I think you should start with determining what you'll use the sub(s) for.
1. It it's for a home theater where it will be connected to the LFE output of a 5.1 set-up, I would defenetly go for a big reflex box.
(haven't tried horns (tapped) but I guess this might also be a good solution). A reflex system will give som much more slam for the buck than a seled system. You need to make it go down to about 35 Hz for a good result, but you don't have to go all the way down to 20 Hz in my perspective/experience.
2. For stereo listening you could make a smaller sealed system. You will probably have to use a Linkwitch transform to make it go deep enough. The smaller the box, and the lower you want it to go, the more power you need (and the more power the sub needs to handle)
As for multiple subs, it's actually a very good idea to minimize room mode influences ... the more the better 🙂
Actually the smaller the room the more problems you'll nrmally have with room modes. (the larger the room the more evenly spread the modes will be and will reduce the problem).
As for reflex/closed, the closed box will sound more "dry". But a well constructed reflex system can to my mind sound really good, and will "breathe" more.
I use 2 x 12" JBL's in a old school 2 x 120 l reflex system with 100 W to each. For movies, it's really scarry, and I have never had to play at more than ½ volume!
http://home20.inet.tele.dk/audio/HomeTheater/Construct.htm
Look at the bottom of the page
For Stereo I just finished my 12" Peerless XLS based sub. It uses 400W, and going down to 20 Hz, it realy need this amount of power to max out. But again you need much higher sound levels for movies than for stereo, so it can easily handle the situation.
http://home20.inet.tele.dk/audio/SubZero/SubZero.htm
I build in a parametric eq to handle the most dominate room mode. It works fine, and can be reccomended, but after I have rebuilt my room, doing a lot to suppres room modes, I don't use it.
And as breez said, the room is what sets the limits for good bass.
Looking forward to hearing/seeing what you ended up with and how it sounds
Best regards Baldin 😎
PS. If you tell us the exact drivers you have, I'll try to do a simulation, and tell you what I would do .... (not all drivers are subwoofer material
)
Any way. I think you should start with determining what you'll use the sub(s) for.
1. It it's for a home theater where it will be connected to the LFE output of a 5.1 set-up, I would defenetly go for a big reflex box.
(haven't tried horns (tapped) but I guess this might also be a good solution). A reflex system will give som much more slam for the buck than a seled system. You need to make it go down to about 35 Hz for a good result, but you don't have to go all the way down to 20 Hz in my perspective/experience.
2. For stereo listening you could make a smaller sealed system. You will probably have to use a Linkwitch transform to make it go deep enough. The smaller the box, and the lower you want it to go, the more power you need (and the more power the sub needs to handle)
As for multiple subs, it's actually a very good idea to minimize room mode influences ... the more the better 🙂
Actually the smaller the room the more problems you'll nrmally have with room modes. (the larger the room the more evenly spread the modes will be and will reduce the problem).
As for reflex/closed, the closed box will sound more "dry". But a well constructed reflex system can to my mind sound really good, and will "breathe" more.
I use 2 x 12" JBL's in a old school 2 x 120 l reflex system with 100 W to each. For movies, it's really scarry, and I have never had to play at more than ½ volume!
http://home20.inet.tele.dk/audio/HomeTheater/Construct.htm
Look at the bottom of the page
For Stereo I just finished my 12" Peerless XLS based sub. It uses 400W, and going down to 20 Hz, it realy need this amount of power to max out. But again you need much higher sound levels for movies than for stereo, so it can easily handle the situation.
http://home20.inet.tele.dk/audio/SubZero/SubZero.htm
I build in a parametric eq to handle the most dominate room mode. It works fine, and can be reccomended, but after I have rebuilt my room, doing a lot to suppres room modes, I don't use it.
And as breez said, the room is what sets the limits for good bass.
Looking forward to hearing/seeing what you ended up with and how it sounds
Best regards Baldin 😎
PS. If you tell us the exact drivers you have, I'll try to do a simulation, and tell you what I would do .... (not all drivers are subwoofer material
)
Rob in this I think I agree, but bought the woofer just before we moved house and as the new lounge/listening area is much smaller than the old I have to put the big TL on hold.
If I could afford a pair of CSS 18 inch subs that's probably what I would prefer, but these drivers are what I have in stock.
Baldwin Hi! and thanks.
They are totally different drivers, both built and sold as car sub-woofers originally.
In the stuffed 155liter sealed box I have a Kicker EX154.
Fs 18Hz / Qes 0.422 / Qms12.08 / X max 10.5mm / Vas 315.7liters Sd 901Cm<2.
When I model it in Jeff Bagbys box program it looks good and it has good depth especially when I use the parametric EQ and give 4dB boost ( wide ) at 31Hz. runs out of excursion at 155 watts
The woofer I have on the shelf is a Cerwin Vega "Vega 154' the big brother to the pai of CV 124's I have in 13litre sealed boxes
( which I do mean to do something better with when time permits )
CV154
Fs 23Hz / Qms 4.42 / Qes 0.390 / Vas 179 liters / Xmax 19mm / Re 3.4 Sd 874cm<2
Power rating on the CV is 400watts RMS peak 800watts
At the moment I do not have an amp which has more than 300 watts available.
Currently I have things set up using both the small CV sealed boxes and the Kicker, SPL for the Kicker exceeds the combined output of the CV 124's especially as I have the XO ( Behringer CX 2310 0 set at 120Hz.
A bit typical for car woofers, you always seem to miss some thiele-small parameters to do a good simulation!
Seems ther are more than one type of Vega 154 .... I took your data and put in an Sd = 860 (not too far off I think). You need more data than provided to simulate cone excursion!
Use Win ISD it realy easy, and very good 🙂
Vega 154 in sealed 50 l: fs=51.8, Qtc = 0.78
400 W in will make it max out and will give 103 db @ 25 Hz. You'll need to use a Linkwitz transform, go for 25 Hz Qtc = 0.5
This will be an excelent sub for music 😉
Vega 154 in 120 l reflex, tuned for 25 Hz.
Will max out at 400 W and will give 111.5 db @ 25 Hz .... awsome for movies 😎
Kicker EX152 (used Re=3.4 as an estimate) in 120 l closed.
fs = 35.7 Hz, Qtc = 0,81
Yes it will need 150 W to max out, and will produce 103.8 db @ 25 Hz
I would again use a Linkwitz transform to make it go deeper ... 35 Hz is a bit high
With a 50 l closed box, you'll need 400 W to make it max out (not sure it will handle this much power) and you could use a Linkwitz transform to make it match a Vega also in a 50 l box! (It will also closely match in output).
The Kicker is not well suted for a reflex system.
Anyway, if you want the two subs to play together (using same input) I would make them match wrt. fs
If the supplied thiele small parameters are correct, I think the Vega woofer is the more interesting of the two. In the 120 reflex box it will really shine.
But each one in a 50 l sealed box with a Linkwitz and enough power you'll probably get very good sounding bass.
http://sound.westhost.com/linkwitz-transform.htm
(If you have 300 or 400 W is not very important, only a few db)
Best regards
Baldin
Seems ther are more than one type of Vega 154 .... I took your data and put in an Sd = 860 (not too far off I think). You need more data than provided to simulate cone excursion!
Use Win ISD it realy easy, and very good 🙂
Vega 154 in sealed 50 l: fs=51.8, Qtc = 0.78
400 W in will make it max out and will give 103 db @ 25 Hz. You'll need to use a Linkwitz transform, go for 25 Hz Qtc = 0.5
This will be an excelent sub for music 😉
Vega 154 in 120 l reflex, tuned for 25 Hz.
Will max out at 400 W and will give 111.5 db @ 25 Hz .... awsome for movies 😎
Kicker EX152 (used Re=3.4 as an estimate) in 120 l closed.
fs = 35.7 Hz, Qtc = 0,81
Yes it will need 150 W to max out, and will produce 103.8 db @ 25 Hz
I would again use a Linkwitz transform to make it go deeper ... 35 Hz is a bit high
With a 50 l closed box, you'll need 400 W to make it max out (not sure it will handle this much power) and you could use a Linkwitz transform to make it match a Vega also in a 50 l box! (It will also closely match in output).
The Kicker is not well suted for a reflex system.
Anyway, if you want the two subs to play together (using same input) I would make them match wrt. fs
If the supplied thiele small parameters are correct, I think the Vega woofer is the more interesting of the two. In the 120 reflex box it will really shine.
But each one in a 50 l sealed box with a Linkwitz and enough power you'll probably get very good sounding bass.
http://sound.westhost.com/linkwitz-transform.htm
(If you have 300 or 400 W is not very important, only a few db)
Best regards
Baldin
Baldin said:
THX style systems (all speakers set to small, 80Hz xo) would require a sub to do ~115dB for reference levels. In my system I'd want response down to at least 12Hz too.
Rob.
This is the thread that gave details of the rebuild of the kicker box.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=144700
As the driver has such high Qms and as I had the caps available I tried the first order high pass, it does provide a little lift down low and by restricting very low frequencies probably increases power handling a little.
I do think the Cerwin Vega is a much better built driver, and the "Vega" series was probably the last of the high quality production.
Looks like I built a smaller sealed box for it, and in the short term i'll set the Fb the same as the Kicker,
When i have the funds/time available i'll take GMs advice and build the CV a decent TL to take advantage of the excursion and power handling
http://www.diyaudio.com/forums/showthread.php?s=&threadid=144700
As the driver has such high Qms and as I had the caps available I tried the first order high pass, it does provide a little lift down low and by restricting very low frequencies probably increases power handling a little.
I do think the Cerwin Vega is a much better built driver, and the "Vega" series was probably the last of the high quality production.
Looks like I built a smaller sealed box for it, and in the short term i'll set the Fb the same as the Kicker,
When i have the funds/time available i'll take GMs advice and build the CV a decent TL to take advantage of the excursion and power handling
sort of pertains to this
I added 9.2 Ohms of series resistance to my OB sub, a Hawthorne 15" Augie. I was basically trying to see what the Amazing Loudspeaker might have sounded like and squeeze more deep bass out of the Augie. There was a suitable resistor (e.g. 9.2 Ohm 1% 50 watt) available at a local surplus supplier www.halted.com for $1.75/ea, so I decided to give-er-a-go. Fancier circuits could have been and still can be implemented to boost bass and waste less power, but this was quick and easy.
The Qts of the Amazing woofer according to many sources on the Web is around 3, the PSI and Augie are more near a normal 0.9. The resonance of the Augie is 27Hz where as the Amazing woofer is usually stated as 22Hz. The equation for adjusting woofer Q with series resistance according to www.trueaudio.com is given as Q(tc) = Q(tco) ( (Re + Rg)/ Re ). The relevant Augie specs according to the www.hawthorneaudio.com are given as Re: 5.69 Ohms and Qt: 0.92. Plugging the numbers into the equation with the 9.2Ohm resistors gives us Q(tc)= 0.92 ((5.69+9.2)/5.69). Our new Q(tc) is then 2.4 if I did my math correctly. That's close enough to the Amazing IMO to see what the effect may be and my additional baffle width will maybe compensate for my lower Q(tc). Of course my Resonant Frequency is also 5Hz higher, but I just don't feel like cutting my baffle today .... This also means that I have virtually no DF, but prior experience has let me unconvinced of it's worth anyway.
I have no measuring equipment, but listening impressions basically go like this: Augie w/o resistor is putting out a lot more midrange, but apparently less deep bass. As far as bass quality goes (the usual fast vs. slow bass argument) I can't tell the difference. Many people claim to hear the effect, but I discovered today that I really cannot. At least not easily. Sort of a bummer. Just yesterday I thought that the quality of bass was mostly determined by Q(tc). Now I don't know what to think. I mean I also thought that OB bass was less affected by the room than boxed bass. Perhaps this is untrue as well?
Just a note on the set-up: I've got a 24 db/octave x-over set just below 60Hz, a 250 watt amp driving the Augie and 25 watt amp on the PSI.
More listening sessions are needed for sure and measurements would be nice, but it's been a fun experiment so far.
Dan
I added 9.2 Ohms of series resistance to my OB sub, a Hawthorne 15" Augie. I was basically trying to see what the Amazing Loudspeaker might have sounded like and squeeze more deep bass out of the Augie. There was a suitable resistor (e.g. 9.2 Ohm 1% 50 watt) available at a local surplus supplier www.halted.com for $1.75/ea, so I decided to give-er-a-go. Fancier circuits could have been and still can be implemented to boost bass and waste less power, but this was quick and easy.
The Qts of the Amazing woofer according to many sources on the Web is around 3, the PSI and Augie are more near a normal 0.9. The resonance of the Augie is 27Hz where as the Amazing woofer is usually stated as 22Hz. The equation for adjusting woofer Q with series resistance according to www.trueaudio.com is given as Q(tc) = Q(tco) ( (Re + Rg)/ Re ). The relevant Augie specs according to the www.hawthorneaudio.com are given as Re: 5.69 Ohms and Qt: 0.92. Plugging the numbers into the equation with the 9.2Ohm resistors gives us Q(tc)= 0.92 ((5.69+9.2)/5.69). Our new Q(tc) is then 2.4 if I did my math correctly. That's close enough to the Amazing IMO to see what the effect may be and my additional baffle width will maybe compensate for my lower Q(tc). Of course my Resonant Frequency is also 5Hz higher, but I just don't feel like cutting my baffle today .... This also means that I have virtually no DF, but prior experience has let me unconvinced of it's worth anyway.
I have no measuring equipment, but listening impressions basically go like this: Augie w/o resistor is putting out a lot more midrange, but apparently less deep bass. As far as bass quality goes (the usual fast vs. slow bass argument) I can't tell the difference. Many people claim to hear the effect, but I discovered today that I really cannot. At least not easily. Sort of a bummer. Just yesterday I thought that the quality of bass was mostly determined by Q(tc). Now I don't know what to think. I mean I also thought that OB bass was less affected by the room than boxed bass. Perhaps this is untrue as well?
Just a note on the set-up: I've got a 24 db/octave x-over set just below 60Hz, a 250 watt amp driving the Augie and 25 watt amp on the PSI.
More listening sessions are needed for sure and measurements would be nice, but it's been a fun experiment so far.
Dan
Sorry Dan but I have never heard of the "Amazing" woofer.
i do think tho that any driver with an inherent Qts of 3 would sound like an undersized sealed box with a huge peak at resonance.
While I haven't finished my trial yet my OB woofers are Qts of 1.2 and already have excessive excursion at resonance, sound good tho.
There has been a lot of discussion on whether OB bass sounds any different to sealed or ported boxes, all I can say is that to my ears sealed boxes sound better in smaller rooms, as they say the room dominates
i do think tho that any driver with an inherent Qts of 3 would sound like an undersized sealed box with a huge peak at resonance.
While I haven't finished my trial yet my OB woofers are Qts of 1.2 and already have excessive excursion at resonance, sound good tho.
There has been a lot of discussion on whether OB bass sounds any different to sealed or ported boxes, all I can say is that to my ears sealed boxes sound better in smaller rooms, as they say the room dominates
amazing loudspeaker: http://www.audioreview.com/mfr/carv...n-amazing-loudspeaker/PRD_119277_1594crx.aspx
simulations of things like what I've done but with the 10" Augie:
And yes, this thing bottoms out much easier now. It never bottomed out w/o the resistor. It just causes you to loose a lot of efficiency and of course control. The Q(tc) in that simulation would be somewhere around 1.5 though as that woofer has a lower Q(ts), but the Hawthorne Audio site doesn't list enough parameters for a proper Q(tc) calculation. None of that was really my point. Sorry if I rambled. Just wanted to state that the high Q(tc) didn't subjectively hurt the sound with my ears and let you know that it was from experience.
simulations of things like what I've done but with the 10" Augie:
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
And yes, this thing bottoms out much easier now. It never bottomed out w/o the resistor. It just causes you to loose a lot of efficiency and of course control. The Q(tc) in that simulation would be somewhere around 1.5 though as that woofer has a lower Q(ts), but the Hawthorne Audio site doesn't list enough parameters for a proper Q(tc) calculation. None of that was really my point. Sorry if I rambled. Just wanted to state that the high Q(tc) didn't subjectively hurt the sound with my ears and let you know that it was from experience.
Thanx for the link; I would personally hate loosing the efficiency OTOH I have experimented a lot with first order high passes a lot and most people think that is a lot of money for little real gain.
Works with these Kickers tho due to high Qms, what happens when you use a smaller resistor? lower peak better power handling I would assume.
I do think it depends on the music you listen to as well, a lot of 60s and 70s rock and roll was mixed to be heard on speakers that had that high "Q" sound, and when played back on good systems does sound a little lifeless
Works with these Kickers tho due to high Qms, what happens when you use a smaller resistor? lower peak better power handling I would assume.
I do think it depends on the music you listen to as well, a lot of 60s and 70s rock and roll was mixed to be heard on speakers that had that high "Q" sound, and when played back on good systems does sound a little lifeless
Oh, I screwed up. Those simulations were for the 15" Augie. Scorpion simulated it 10" from the floor. I was just tired and misread his reply to my post on another forum. So no Boom with my resistor. He did another simulation with my exact baffle and said it turned out pretty much the same.
I don't think I'd recommend the resistor method for anyone looking to get the most out of their stuff (I think most of us are trying to do just that). I just wanted to do a little experiment for my own personal knowledge. It seemed to fit into the thinking of this thread so I posted it here as well.
I don't think I'd recommend the resistor method for anyone looking to get the most out of their stuff (I think most of us are trying to do just that). I just wanted to do a little experiment for my own personal knowledge. It seemed to fit into the thinking of this thread so I posted it here as well.
Resistors are cheap and I imagine the experiment took only a little time.
Experiments are what DIY is all about.
As I have said many times "One of these days i have to get a microphone and a decent sound card"
The older and deafer I become the less I trust my ears
Experiments are what DIY is all about.
As I have said many times "One of these days i have to get a microphone and a decent sound card"
The older and deafer I become the less I trust my ears
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