2x Peerless SLS-10 Transmission Line Sub

[michaelpage26]

Hi,

I am planning (not for the near future though) to build some TL subwoofers. If I wanted to build a TL with 2x SLS 10" in a style shown here
what dimentions of PVC pipe would I need (length,diameter, etc)
The SLS series seem really good for Transmission Line Subwoofers, since they are being used in designs from Klang +Ton :
http://www.lautsprechershop.de/hifi/ct221_en.htm
http://www.lautsprechershop.de/hifi/ct220_en.htm
Are they really so good to be partnered with a good pair of full-range electrostats?

Thanks in advance
Mike

[Tomac]

I would rather use one driver per pipe and build two pipes. You haven't written how high is your ceiling.
Pipe diameter: 30-35cm according to what you can get there
Length of pipe 220-280cm according to what you can fit in your room
Place it in corners, put some stuffing in it and enjoy
good luck

[michaelpage26]

Hi again,
My ceiling is 250-260cm

Length of pipe 220-280cm according to what you can fit in your room

Well the length isn't calculated as the 1/4 of wavelength of something?

Pipe diameter: 30-35cm according to what you can get there

They say that it has to be about 100-120% of the Sd, which is translated to 21 for the diameter
If I put two I will have find a 40 pvc pipe ?
What if I use a single 12" SLS ?
How do you measure the dimensions needed in a sonotube TL subwoofer?
Have you designed any like the ones I want to build?
May be a safer bet to buy the kits from lautsprecher-shop?
Thanks for the help, and any upcoming...

Regards,
Mike

[GM]

Greets!

Yes, well stuffed pipes are good for blending to 'fast' systems such as electrostats and horns.

Yes, some folks design them to be a 1/4 WL of Fs, but that's not necessarily best for the app and rarely is the 100-120% of Sd pipe area rule-of-thumb.

You don't say what your XO point is or how low you want them to go, but the lowest practical Fp requires a long, large pipe for just one driver, too tall for your room without folding it. If a ~40 Hz Fp is an acceptable limit, then for a single SLS-10, a relatively compact downfiring pipe can be used, ~122 cm long and at least 31 cm in diameter and vary the distance to the floor to find the optimal loading, then add stuffing to smooth it out if need be. If you want to do a bipole, then the pipe's area doubles, or at least a ~44 cm diameter pipe is required.

A typical sonotube sub is calc'd the same as any other box sub, though with MJK's worksheet you can sim it a bit more accurately except for any gain due to floor slot loading.

GM

[michaelpage26]

Thanks for the help guys ....

Where can I find the MJK WorkSheet?
For my room is it better to use a single SLS 12" ? What dimensions will I need in this case?
I have noticed that SLS series is near perfect for open baffle subwoofers...Can it be near perfect for TL in the same time?
I need a crossover about 120Hz to be sure (if I buy the smaller ESL III electrostat from www.eraudio.com.au) or about 80Hz (if I buy the bigger Acorn electrostat from www.eraudio.com.au).
The Fp is the useful frequency in an anechoic room?
Well if I tune it to about 35 Hz, it can go easily down to 20hz with help of the room...
What do I need to stuff the pipes with? All the tuning is being done only with this stuff?
Are the sonotube TL equal or better to traditional foldpiped TL (or not)?
Is it considered bipole if I put two woofers in the same cabinet and then put a pvc pipe on it? I will still have to double up the diameter, right?

Sorry for so many questions?
Best Regards,
Mike

[simon5]

Martin J. King work is available here :

http://www.quarter-wave.com/

[GM]

Greets!

You're welcome!

The object of a traditional TL is to mimic an IB response in a smaller cab, ergo the ideal driver is the same for either.

OK, so the driver has to have a smooth response out to several hundred Hz, so drivers with a low Le and well controlled break-up is preferred. This type driver tends to be relatively expensive though, so the SLS-10 seems 'on paper' to be a reasonable compromise.

The SLS-12 has a marginally lower Le, greater acoustic efficiency, ergo a little more dynamic headroom, so is the better choice overall, though if it's a lot more then it's not worth it since you will want at least two drivers, one/channel.

Yes, stuffing is the tuning adjustment. It's typically loose polyfil, fiberglass insulation or Miraflex, an itchless fiberglass insulation. The latter two are more dense, so less is required.

If the folded TL is a constant taper like the sonotube, then they should perform the same. Many traditional TLs are reverse tapered though, or what's known today as mass loaded, so will be shorter than a constant taper TL for a given Fp.

Bipole is when two drivers are mounted opposite each other and if you're going to build a box, why bother with doing the extra effort mating one big or two smaller sonotubes to it? Just make the box the right area and taller, folding it if it's too tall to fit in-room.

Anyway, the ~same bottom firing alignment with the 12" as the 10" would be ~134 cm long and at least 41.2 cm in diameter. For 35 Hz, ~235.4 cm long, 34.6 cm diameter. If the sims are to be believed though, there's not enough difference in their responses to be audible, especially once you factor the room in. Not surprising really since the driver has a ~critically damped Qts.

GM

[michaelpage26]

Thanks GM for your help!

But I have some things that need some light to be shed...

What exactly is Fb?
Why lower Le is better?
What values should I seek for in Qes, Qts and Qms for TL sonotubes?

Anyway, the ~same bottom firing alignment with the 12" as the 10" would be ~134 cm long and at least 41.2 cm in diameter. For 35 Hz, ~235.4 cm long, 34.6 cm diameter.

With the 134 cm and 41.2 cm in diameter, --> how much Hz?
I am asking this silly questions because previously you said that stuffing is the tuning adjustment....or the length/diameter of the pipe is ideally selected from a simulator for a certain tuning?

Also in the quote above, you seem to say that it doesn't matter if it's 10" or 12"...But this way the Sd changes-->so does the diameter...
As a result if we put two 12" in a box and pipe, and then we remove the one 12" it won't be needed to change the box/pipe dimensions?

Finally, please make some suggestions for more suitable 8ohm drivers for TL sonotube designs (to be blended with electrostats) in the range 300-400$- either 1x12" or 2x10" per channel...My room is 250cm tall- which height pipes can i fit inside, without performance degradation? I am seeking for really deep and clean bass, with great impact (not neccesary extended)...
Also which simulation software do you recommend for TL? (it isn't the MJK-is it?)
Thanks in advance for spending your time sheding light to my numerous questions

[simon5]

Le is the inductance of the driver. It acts like a lowpass filter. If Le is lower, then the lowpass filter is higher in frequency. Higher Le can also exhibit slight delay in the bass.

Fb is the tuning frequency of a box.

[michaelpage26]

I am also considering the Visaton TIW 200 XS. It seems REALLY great for a 8". I have heard the bass from Visaton GF 200 (similar sounding with higher Fs) used in the Greek made Mythos Audio Aenaon (see picture) and it was really stunning in the bass and mid-bass range!
I wish I could clone it (not an easy task : Transmission Line+Horn Loaded+tweeter in special base)
Are the Visaton TIW200 XS suitable for sonotube TL at 30hz tuning? Here are the specs:

* power handling (continuous/programme) = 120 / 180 W
* resonance frequency fs = 26 Hz
* impedance R = 8 Ohm
* sound pressure level SPL = 84 dB (2,83V; 1m)
* DC resistance Re = 6,1 Ohm
* force factor BL = 9,1 N/A
* voice coil inductance L = 1,6 mH
* effective piston radiating area Sd = 206 cm2
* effective mechanical mass incl. air load 35 g
* equivalent volume of compliance Vas = 65 l
* total Q factor Qts = 0,42 (Qms=5,27, Qes=0,45)
* maximum peak linear excursion vibration xlin = +/- 11 mm
* BL = 8,7 Tm
* mounting diameter d = 189 mm
* overall diameter d = 222 mm
* mounting depth (not countersunk) t = 108 mm


Or the Visaton GF 200 is more suitable for blending with Electrostats?