line array + transmission line ?

[zobsky]

I have a large number of 3" drivers coming my way and intend to try my hand at building a line array.

Searching this forum, I've seen instances of sealed, ported or open baffle line arrays. I'm wondering if a TL type might work too. Bill Fitzmaurice has something like this (TLAH). Like the TLAH, I intend to build mine to be corner loaded, but am considering a larger number of drivers (18 - 20 ) .

Questions regarding the bass-mid bass tuning:

1. I haven't yet got an idea of the driver paramters, but I'm suspecting an Fs of around 100 - 150 Hz. Let's assume a line length of 2 metres for convenience. In a TL loaded line array, .. the drivers are positioned pretty much all along the length of the pipe. Does it make more sense to partition the line into two smaller lines of 1 m each for a quarter wave line freq of 85Hz, or maintain a straight 2m line of 42 Hz qarter wave frequency. I realize that these numbers can be misleading as the drivers would load the line throughout its length, not just at the closed end.

2. Would it be better to taper the line, .. or mass load the terminus, or both.

3. Also, any reccomendations on the cheap 20c parts express onkyo tweeters vs. the apexjr tweeters (50c each i believe)

Sorry if the questions seem naive..

 

[RJ]

Something like this?

I beleve someone in England is building this.
As for the tweeters they're the same.

 

[tinitus]

I recommend that you arrange centers of all drivers on a "curve" that represent a radius from your ears

 

[zobsky]

Something like this?
.
.
I beleve someone in England is building this.
As for the tweeters they're the same.

Yes, .. that's one of the TL options i was considering, .. the other two being
1. mass loading the terminus with a port
2. maintaining two short TL sections (upper and lower), . without bothering with the extra folds as in your diagram.

As for a curved array suggestion, I'll fight that battle next, after deciding upon the bass alignment.

 

[johninCR]

One of the projects on my todo list is to try one of my OB arrays as a TQWT. I believe that multiple drivers will help smooth out the typical lumpy Voight pipe response. Additionally, it would be a much easier construction than what you have pictured and the cab height for the array will be part of the line length.

 

[zobsky]

One of the projects on my todo list is to try one of my OB arrays as a TQWT. I believe that multiple drivers will help smooth out the typical lumpy Voight pipe response.

Not sure if want to go voight pipe, but I was thinking along the same line ie. multiple drivers along the entire line should even out the peaks and dips.

I do wish the TL Gods (Dave, GM, Martin ...)would add their 2c of wisdom

 

[johninCR]

The wings on my array are tapered, so it already has a TQWT shape and the conversion would be easy. A straight MLTL is an option as is a multi-driver BIB horn (see the fullrange forum). It just depends on how big you are willing to go with the footprint. As drawn yours looks more like a giant vent BR to me.

 

[tinitus]

As far as I know, in a TQWT it is very important where in the "line" you position the driver, so I guess LineArray isnt suited fore this

 

[tinitus]

Why not simply make it into a double BR, the simplest is often the best, but admittedly not the most exciting

 

[zobsky]

As far as I know, in a TQWT it is very important where in the "line" you position the driver, so I guess LineArray isnt suited fore this

point taken, .. i agree that not all the drivers will be loaded equally (or even adequately) in an arrayed line, but various drivers along the line could possibly yield benefits by evening out the bass response . this is kind of a "shotgun" approach

Why not simply make it into a double BR, the simplest is often the best, but admittedly not the most exciting

i think an arrayed line would be as simple (or simpler) than a bass reflex

 

[planet10]

If the Fs is that high the line won't be very long... especially if you do a severe taper or an ML-TL(say 20" just to have something to work with) ... just load a TL behind each driver (or pair) and send the line straight out the back or ivv you could fold it....

dave

 

[bjorno]

Hi,

Example of short TL-line-arrays. For 5.1 lateral use with surround channels.

B

 

[zobsky]

Thanks, .. I'll post back in a week or less, when I have the drivers in hand.

bjorno, .. that idea is neat but would need more space than I can afford for this application.
Dave, .. likewise, I was considering having the line run along the length of the speaker, rather than across.

Hopefully, I can hack out something this weekend, if I get the drivers before then. Hopefully, they'll work out fine.

Watch this space, and keep the suggestions coming. I haven't bought any tweeters for the high frequency array yet, but have several toys to work with in the meantime (piezos, linaeum dipoles, eminence compression drivers, RS supertweeters)