ppia600 said:
because you have two magnets and two voice coils...
the volume of air being moved is exactly the same...
do you actually know what an isobaric enclosure is?
I chose a conventional box over isobaric, because I dont have any space issues, and because I was going for all out SPL, and didn't want to lose efficiency.
TWOJZ said:
Ok, gotcha.
Ok, apparently I don't know what an isobaric is
I was thinking of the type where you use the woofers in almost a V configuration, sometimes band passed, sometimes just sealed. Let me try and draw something. An externally hosted image should be here but it was not working when we last tested it.
/\/\ My atari box skillz . The box design on the left is what I thought you were talking about. I still would rather use a single beefier woofer like a kicker solobaric over two woofers.
So you are talking about isobaric like the polk C4 bandpass box that had the four 6x9" subs then, right?
I actually built my own like the c4 but I used four bostwick 8" subs, sounded nice at 4 ohms mono on my old a600.
ok so what if i keep the box the same size as im using for the normal sub setup?
im assuming it will regain the -3db loss, play even lower and be tighter do to the increased motor force...evethough iso reduces box size i dont see any reason i would have to do that.
normally i would 'just do it' and see what happens, but my jigsaw died, so cant exepriment yet.
ppi600 i think your talking about clamshell boxes.
im assuming it will regain the -3db loss, play even lower and be tighter do to the increased motor force...evethough iso reduces box size i dont see any reason i would have to do that.
normally i would 'just do it' and see what happens, but my jigsaw died, so cant exepriment yet.
ppi600 i think your talking about clamshell boxes.
This seems to be turning into a philosophical discussion.
adason wrote:
You are back to about the same output, but not the same efficiency.
You have half the cone area as two woofers and are having to use twice the wattage to drive them to the same output.
I can see why you had to leave it! I've done some that have turned out very well, too. With today's automotive woofers there's usually no reason to go isobaric.
The key to answering the original poster's question is in his last line:
If both choices are optimum subwoofer enclosures, isobaric isn't the way to go.
Tim
adason wrote:
You are back to about the same output, but not the same efficiency.
You have half the cone area as two woofers and are having to use twice the wattage to drive them to the same output.
I can see why you had to leave it! I've done some that have turned out very well, too. With today's automotive woofers there's usually no reason to go isobaric.
The key to answering the original poster's question is in his last line:
If both choices are optimum subwoofer enclosures, isobaric isn't the way to go.
Tim
sreten said:
TWOJZ said:
Hi,
I actually put together an isobaric before and measured the resonant peak with Speaker Workshop. This is what I based my statement on.
The trapped air between the drivers mass loads the cones. Fs is lower.
Vas (can be) reduced to half, to achieve the same tuning frequency as a single driver in a smaller box, or you could use the single drivers VAS to get a lower tuning, although this may result in peaked response (depends on the drivers)
pinkmouse said:no one seems to have mentioned the advantage of distortion cancellation yet.
Yes, as long as you mount them up push-pull (which to be most effective means face-to-face)
One of these days i mean to do a push-push-push-pull box... with the new SDX-7 one could have a crital Q sealed box in 21 liters
dave
Attachments
planet10 said:
Hi Dave,
I'm probably wrong. The two woofers I used were of the same type and size, but they measured differently. This might have given me the misleading info.
planet10 said:
Nice idea. What about surrounding it with another box with the centre open? Stands up and fires front and back.
I might try this myself.
Attachments
If you're using the two woofers in a "push pull" configuration, what equalizes the load on both woofers besides the small sealed air gap between them? I know the center section is supposed to be airtight and theoretically the small air mass should keep both woofers in sync, but it seems that the one sealed chamber woofer would require more effort, then the small area between the subs would act as a cushion to some extent and allow the outer enclosureless woofer to behave differently. Especially considering the larger pressure difference between the sealed enclosure woofer side and the open air woofer side. ??????
1.what effect would the space between the woofers have?
i would want to try mounting the subs, both pointing in the same direction, isnt this called compound loading?
what about the direction the subs ar pointing, for example, if i point the inner sub forward and the second sub pointing up,so that they would be mounted at a 90 degree angle from each other? ("L" shape)
2.which would be louder, 3 subs or 3 isobaric pairs? (optimum enclosure)
i would want to try mounting the subs, both pointing in the same direction, isnt this called compound loading?
what about the direction the subs ar pointing, for example, if i point the inner sub forward and the second sub pointing up,so that they would be mounted at a 90 degree angle from each other? ("L" shape)
2.which would be louder, 3 subs or 3 isobaric pairs? (optimum enclosure)
I have built two isobarik ported sonosubs and they work exactly as I expected. In fact, the larger (using two 10s) is one of my best subs, giving very tight transients and playing down to the lower 20s.
Once I put a port extension on this sub that tuned it to about 6 Hz. It was inaudible of course, but it was obvious that the port was controlling the cones. Then I noticed that the port was acting as a transmission line up around 250 Hz or so!
Actually both drivers experience the same pressure differential from one side to the other. The inner driver contributes half the pressurizing force and the outer driver the other half, by making it easier for the inner driver to move against the stiff spring of the halved air volume. It does this by virtue of being close coupled to the inner driver. Sure the tiny volume between face-to-face drivers gives a little, but this effect is swamped by the much larger compliance of the main air volume and is practically negligible.
So for identical drivers, the changes from single driver to half-volume, 2-driver isobaric are:
*working volume is halved
*moving mass doubles
*Bl doubles
*Fs essentially unchanged
*compliance is halved
*air displacement unchanged
*Vb unchanged (though port length must increase accordingly, resulting in long, potentially ungainly ports or unusably small diameters)
*sensitivity drops by 3 dB for same power, or twice the power is required compared to one driver in unhalved volume
*twice as many drivers required
*distortion due to 'in' vs 'out' nonlinearities is greatly reduced
did I miss anything?
And now my question: How close do Kicker Solobaric drivers actually come to meeting the pertinent points? Has anyone done A/B testing or measurement?
And is this right:
If we don't halve the volume, but nonetheless isobarically load the box, the drivers essentially see double the optimum volume and there may be response irregularities (of what type?) and possibly greater susceptibility to overexcursion? But, since the drivers see double the volume, doesn't this mean a 3dB gain in enclosure LF efficiency due to doubled box volume, thereby canceling out the 3dB loss due to twice the power but no additional displacement??? ??? That one has always confused me!
"Continuing in the same vein," what if we not only don't halve the volume, but also lengthen the port to lower the tuning, like you might do for an extended bass shelf alignment? Presumably this would have the potential to create midbass dips and make the driver very sensitive to overexcursion below Fb and possibly in the midbass as well? But the Qts doesn't change in isobarik, does it, whereas the low efficiency drivers favored for extended bass shelf would have a fairly high Qts?
Thanks in advance to anyone who even tries to tackle all those questions!
Once I put a port extension on this sub that tuned it to about 6 Hz. It was inaudible of course, but it was obvious that the port was controlling the cones. Then I noticed that the port was acting as a transmission line up around 250 Hz or so!
Actually both drivers experience the same pressure differential from one side to the other. The inner driver contributes half the pressurizing force and the outer driver the other half, by making it easier for the inner driver to move against the stiff spring of the halved air volume. It does this by virtue of being close coupled to the inner driver. Sure the tiny volume between face-to-face drivers gives a little, but this effect is swamped by the much larger compliance of the main air volume and is practically negligible.
So for identical drivers, the changes from single driver to half-volume, 2-driver isobaric are:
*working volume is halved
*moving mass doubles
*Bl doubles
*Fs essentially unchanged
*compliance is halved
*air displacement unchanged
*Vb unchanged (though port length must increase accordingly, resulting in long, potentially ungainly ports or unusably small diameters)
*sensitivity drops by 3 dB for same power, or twice the power is required compared to one driver in unhalved volume
*twice as many drivers required
*distortion due to 'in' vs 'out' nonlinearities is greatly reduced
did I miss anything?
And now my question: How close do Kicker Solobaric drivers actually come to meeting the pertinent points? Has anyone done A/B testing or measurement?
And is this right:
If we don't halve the volume, but nonetheless isobarically load the box, the drivers essentially see double the optimum volume and there may be response irregularities (of what type?) and possibly greater susceptibility to overexcursion? But, since the drivers see double the volume, doesn't this mean a 3dB gain in enclosure LF efficiency due to doubled box volume, thereby canceling out the 3dB loss due to twice the power but no additional displacement??? ??? That one has always confused me!
"Continuing in the same vein," what if we not only don't halve the volume, but also lengthen the port to lower the tuning, like you might do for an extended bass shelf alignment? Presumably this would have the potential to create midbass dips and make the driver very sensitive to overexcursion below Fb and possibly in the midbass as well? But the Qts doesn't change in isobarik, does it, whereas the low efficiency drivers favored for extended bass shelf would have a fairly high Qts?
Thanks in advance to anyone who even tries to tackle all those questions!
I have done many iso setups.
I dont have time to read this thread now (when I am making this post) but I see allot of weight to the TSP #'s.
From a pure listening point of view 6 subs iso'ed have the same exposed cone as 3 normally mounded drivers, and produce the same SPL as 3.
-------BUT-------
In most cases they sound better, they are tighter, seem to play lower and response is quicker.
I remember (back in the day [I love saying that]) when the Kicker solobarics came out. We did a bunch of testing of the Solo 15 Vs. a pair of the Comp 15s isoed.
The comps were louder (higher efficiency)
The comps played lower
The comps sounded better
I have also seen a pair of super cheap drivers (like Jensens) sound great when isoed.
It may be just my opinion but a set of ISO drivers has some SQ advantages over a traditional mounded driver.
I dont have time to read this thread now (when I am making this post) but I see allot of weight to the TSP #'s.
From a pure listening point of view 6 subs iso'ed have the same exposed cone as 3 normally mounded drivers, and produce the same SPL as 3.
-------BUT-------
In most cases they sound better, they are tighter, seem to play lower and response is quicker.
I remember (back in the day [I love saying that]) when the Kicker solobarics came out. We did a bunch of testing of the Solo 15 Vs. a pair of the Comp 15s isoed.
The comps were louder (higher efficiency)
The comps played lower
The comps sounded better
I have also seen a pair of super cheap drivers (like Jensens) sound great when isoed.
It may be just my opinion but a set of ISO drivers has some SQ advantages over a traditional mounded driver.
Jonny,
Thanks for your response about the Solobarics. That was exactly what I was looking for, just wondering if they were worth the money. What model of comps did you use? It sounds like anything reasonable might outperform the Solobarics sonically, and SPL-wise as well if high enough power. Were those cabs ported?
I agree with your sonic observations. My 10" iso uses cheap Pyramid drivers, but it is very tight, low, and sounds great. In my car, it literally sounds like a small version of an EAW SB850 driven by a Crown MacroTech! Not as loud of course, but the same exact kind of chest-thumping tightness with the bass drum hits. Note that this iso is driven by an old Coustic 35 wpc amp that I beefed up the rail filter caps on, and the cables are 14 Ga and only 18" long, so I'm probably getting decent damping factor. Fb is set around 26 Hz right now. (is is fitted with a changeable port.)
I also built an 8" iso using very cheap no-name drivers from MCM or something, not even any T/S specs, and driven by a small chip amp I concocted when I was first starting out in audio. I have not done extensive testing of this unit, though, because it serves as my mouse table/ computer sub right now and I haven't had the time. I probably will soon, though. However I had the same compound pair temporarily mounted in a cheap, unreinforced S**y enclosure of the same volume downstairs at one time, and in my listening position it made a great sub. The silly thing would do 20 Hz!I Vb=2300in^3 (37.7 l), Fb ~ 20 Hz.
Overall, iso seems to be a very viable solution to building speakers whenever absolute maximum possible SPL is not a necessity.
Thanks for your response about the Solobarics.
That was exactly what I was looking for, just wondering if they were worth the money. What model of comps did you use? It sounds like anything reasonable might outperform the Solobarics sonically, and SPL-wise as well if high enough power. Were those cabs ported?I agree with your sonic observations. My 10" iso uses cheap Pyramid drivers, but it is very tight, low, and sounds great. In my car, it literally sounds like a small version of an EAW SB850 driven by a Crown MacroTech! Not as loud of course, but the same exact kind of chest-thumping tightness with the bass drum hits. Note that this iso is driven by an old Coustic 35 wpc amp that I beefed up the rail filter caps on, and the cables are 14 Ga and only 18" long, so I'm probably getting decent damping factor. Fb is set around 26 Hz right now. (is is fitted with a changeable port.)
I also built an 8" iso using very cheap no-name drivers from MCM or something, not even any T/S specs, and driven by a small chip amp I concocted when I was first starting out in audio. I have not done extensive testing of this unit, though, because it serves as my mouse table/ computer sub right now and I haven't had the time. I probably will soon, though.
However I had the same compound pair temporarily mounted in a cheap, unreinforced S**y enclosure of the same volume downstairs at one time, and in my listening position it made a great sub. The silly thing would do 20 Hz!I Vb=2300in^3 (37.7 l), Fb ~ 20 Hz.Overall, iso seems to be a very viable solution to building speakers whenever absolute maximum possible SPL is not a necessity.
H/T sub
I have GREAT results using 2 mtx 5500's, in clamshell configuration. The sub cabinet is behind my 52" TV in the cornor so space is tight , its in a 3.5 cubic sealed .
YES two drivers in 3.5 cubic each Would put out 4 DB more but it would recquire another 3.5 cubic box (that I cant fit) ..
So I turned to WINISD to see what happens before I built .
The sub frequency is only down 7.5 DB at 20 hertz !
Since the sub is in the cornor I also get gain from the three walls .
Bottom line this sub goes louder and deeper than any other sub I ever had !
I drive it with a crown XLS 402 and a externall xover .
I want to try running a ISO in a car but since most car subs (min 10") only need like a cubic foot the gain in going smaller is not needed .
But if I had a pair of 15's and dont have the trunk room for 2 big boxes , I would like to try them in a iso box .
Has anybody tried that in a car ?
I have GREAT results using 2 mtx 5500's, in clamshell configuration. The sub cabinet is behind my 52" TV in the cornor so space is tight , its in a 3.5 cubic sealed .
YES two drivers in 3.5 cubic each Would put out 4 DB more but it would recquire another 3.5 cubic box (that I cant fit) ..
So I turned to WINISD to see what happens before I built .
The sub frequency is only down 7.5 DB at 20 hertz !
Since the sub is in the cornor I also get gain from the three walls .
Bottom line this sub goes louder and deeper than any other sub I ever had !
I drive it with a crown XLS 402 and a externall xover .
I want to try running a ISO in a car but since most car subs (min 10") only need like a cubic foot the gain in going smaller is not needed .
But if I had a pair of 15's and dont have the trunk room for 2 big boxes , I would like to try them in a iso box .
Has anybody tried that in a car ?
yeah, seems like iso might be an awesome configuration for car-audio where space is majorly at a premium. I've been thinking about building a center console for the front of my van with some up-front sub action for more balanced front-rear sub bass.
Currently, with the subs in the back, to balance the subs for the driver, you've got to crank them a bit. Anyone sitting in the back seat gets too much.
Seems like an iso setup might be optimal for getting good solid bass from a small enclosure up front. Since the woofers will now be very close to the intended listeners, the drop in efficiency is not really a problem.
Currently, with the subs in the back, to balance the subs for the driver, you've got to crank them a bit. Anyone sitting in the back seat gets too much.
Seems like an iso setup might be optimal for getting good solid bass from a small enclosure up front. Since the woofers will now be very close to the intended listeners, the drop in efficiency is not really a problem.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.