Recently i have been toying around with doing a push-pull-push-push TL sub design. On this forum this topography was brought up. The only downside to this design is you have the speaker baskets sticking out of the enclosure. I was just wondering if somthing like this would still work. I'm thinking that a possible reason it may not work is that there is a much greater air volume between the two drivers as opposed to the original design where they are facing eachother. I'm thinking the two paris of drivers would be in a sonotube that fits snugly around the circumfrence of the driver. Is this just a dumb idea, or is there a chance something like this would work?
It will work just as well as the other arrangement.
Though why you'd use isobaric in a t/l has me mystified.
A push pull pair would seem to be the most sensible.
🙂 sreten.
Though why you'd use isobaric in a t/l has me mystified.
A push pull pair would seem to be the most sensible.
🙂 sreten.
Well i have 16 of these 10'' drivers sitting around my house, i got them for about $5 each. I'm really looking for some way to use them up. I read that having this configuration helps cancels out any non-linearitis in the speaker, so I mighnt as well use 4 even if there is only a marginal improvement in sound.
A single pair in push pull will cancel non linearities.
Have you the specs of the drivers ? some are much
more suited to isobaric pairing than others.
You can use 2 isobaric pairs in the same box as
a single driver, but a t/l would need 2 x the area.
🙂 sreten.
Have you the specs of the drivers ? some are much
more suited to isobaric pairing than others.
You can use 2 isobaric pairs in the same box as
a single driver, but a t/l would need 2 x the area.
🙂 sreten.
Chris8sirhC said:so I mighnt as well use 4 even if there is only a marginal improvement in sound.
Build it. I want to know how it turns out because I have a dozen (!) drivers lying around doing nothing. I'd like to try something using two drivers in tandem somehow. So, if yours is successful, then mine will be too. If yours fails, then I'll learn at least one thing NOT to do.
Dave
sreten said:
I think the arrangement has a wonderful symmetry and would cancel both even harmonics and much of the cabinet vibrations. But as you say, that would happen also with a non-isobarik, 2 driver, push-pull arrangement. Shouldn't it be called push-pull-pull-push, though? 😉
I am unfamiliar with TL dimensioning though, I would have thought that it would have worked just as with the box. How is the cross-sectional area usually selected in a TL?
here is a link to the specs I think i read that the cross sectional area of the transmission line should be between 100% and 125% of the drivers surface area.
*Power Handling: 30 watts RMS/60 watts max *VCdia: 1" *Le: 1.50 mH *Znom: 8 ohms *Re: 7.20 ohms *Frequency range: 44-2,000 Hz *Fs: 44 Hz *SPL: 92 dB 2.83V/1m *Vas: 3.57 cu. ft. *Qms: 5.80 *Qes: .90 *Qts: .78 *Xmax: 3 mm *Driver Dimensions: A: 10-1/4", B: 9-3/8", C: 4".
Well thats a whopping Vas for a 10" driver with a 0.8 Qts.
And Xmax is not impressive.
Sensistivity is pretty good.
What do you expect for $5 dollars ?
How to use them effectively is a major issue.
Reflex is out of the question, except at huge cabinet volumes.
Sealed box possibly, in isobaric configuration, but tight bass is
not on the agenda unless you use a Linkwitz transform.
I'd say twin 4x10 open baffles for low power valve equipment,
assymetrically crossed over to an open baffle full ranger around
92dB/W, such that the bass has already lost 6dB.
For all sixteen units possibly twin opposed paired 4 x 10 arrays,
similar to the SL6 dipole subwoofer, but I readily admit the theory
of such units has me somewhat perplexed.
(Push pull can be easily used in dipoles, isobaric has no advantage)
🙂 sreten.
Well thats a whopping Vas for a 10" driver with a 0.8 Qts.
And Xmax is not impressive.
Sensistivity is pretty good.
What do you expect for $5 dollars ?
How to use them effectively is a major issue.
Reflex is out of the question, except at huge cabinet volumes.
Sealed box possibly, in isobaric configuration, but tight bass is
not on the agenda unless you use a Linkwitz transform.
I'd say twin 4x10 open baffles for low power valve equipment,
assymetrically crossed over to an open baffle full ranger around
92dB/W, such that the bass has already lost 6dB.
For all sixteen units possibly twin opposed paired 4 x 10 arrays,
similar to the SL6 dipole subwoofer, but I readily admit the theory
of such units has me somewhat perplexed.
(Push pull can be easily used in dipoles, isobaric has no advantage)
🙂 sreten.
I always figured that OB subs would have to be huge, im not sure if i have that much space for speakers to take up. Maby since their qts is near .76 i could just do an IB experiment with 4 or so of the drivers along with the TL.
sreten said:
Since line cross-section is related to the Vas, a PPPP TL would use the same X-Section as a single driver. With the typical large size of a TL you can get some serious savings in cabinet size.
Chris8sirhC said:
I came up with the idea because i have 8 cheap 10s kicking around.
dave
Your design is an alpha TL... this is what falls out... a line 63 3/4" long, 18 3/4" internal (square prism) stuffed with 3.53 pounds of polyfluff.
dave
dave
planet10 said:
How does one select the cross-sectional area? Related to Vas makes sense to me, but how?
planet10 said:
That does make more sense than making CSA x1 to x1.25
of the cone area, something I've never understood.
Do you know the basic effect of the driver Q in a TL ? I assume
highish Q needs more stuffing, but theres probably more to it.
🙂 sreten.
Svante said:
You plug the driver specs into one of the models and see what comes out. You can use Martin King's models directly, or you can use one of the subset calculators Rick Shultz has generated using Augspurger's model (only the alpha TL has been published so far (alphaTL = a staright pipe with driver at the closed end)
sreten said:
Probably the best way to get a handle on this is to download Martins tables and just look at them... i do know that in an alpha TL as Q goes down, cross-section tends to increase (hence the spec that drivers with 0.5<Q<1.0 work best.
dave
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