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-   -   W4-1320 TL or Horn or Ported (http://www.diyaudio.com/forums/full-range/204112-w4-1320-tl-horn-ported.html)

VEC7OR 9th January 2012 12:58 PM

W4-1320 TL or Horn or Ported
 
I'm planning to make some loudspeakers for my GF,
at first I was thinking needles, but right now I've ordered a pair of W4-1320,
I haven't seen much TL projects for it except for TABAQ.
back loaded horn enclosure appears to be very large (or I'm using HornResp incorrectly)
Right now I'm constraining on geometrical dimensions, lets say max 15x15x140cm and planning to hit atleast 65Hz (55 ?), most likely speakers will be against a wall.

I have a few questions regarding this endeavor:

1) Can 65-55-45Hz produced with a reasonable listening levels ?
2) Can I simulate TL's with HornResp or I'm better with dedicated spreadsheet for them ?
3) I'm getting ripples in my Hornresp response, what can I do about them, can they be damped - lining the horn with absorbent material? More to that - why are they present in the first place, increasing horn size reduces ripples though.
4) Back loaded horn is effectively a comb filter, how do you reduce this effect ?
5) Is my dimension constrain unreasonable ?
6) I can machine my enclosures on CNC, what neat tricks I can use in my case (smooth contours and bends are included), like things to reduce internal reflections and whatnot ?
7) Placing horn's mouth near the floor effectively enlarges the mouth, by how much, can any mouth contouring improve this ?

hm 9th January 2012 11:47 PM

vec7or
 
2 Attachment(s)
Hello,
a few points you didnīt get by using a double horn,
look Kornett or Trombone or mini Posaune,

small enclosure only 60-80 L, lowest membranmovemet,
eliminate the bass resonanz, down to 35 Hz, best soundstage.

Bjohannesen 10th January 2012 09:54 AM

Hi Vec7or,
Mine TABAQ is now playing with the 4" 1320, and I am very pleased with the sound. The bass is very clean - you might find it too tight. In that case use about 70 gram of damping instead of the 100 gram.

http://static.diyaudio.com/forums/ga...ABAQ_4_SPL.jpg

VEC7OR 19th January 2012 12:43 PM

So far I'm gravitating toward TABAQ, but still, can anyone answer my questions ?

Scottmoose 19th January 2012 03:47 PM

1/ Depends what you call 'reasonable.'
2/ No (unless David has added a damping facility), but you can simulate an undamped QW pipe. For TLs, you're better off with Martin King's MathCAD worksheets.
3/ Yes, you can attenuate them to a greater or lesser extent by strategic damping. If a horn is undersized for the nominal tuning frequency you have an acoustic impedance mismatch at the terminus, and a standing wave reflected back along the horn.
4/ See above.
5/ Dpends on how stringent your (or rather your GF's) performance criteria are for the speakers.
6/ Depends on the box. I generally avoid smooth internal contours for back-horns, since they promote greater efficiency at the top of the cabinet BW, while having relatively little effect lower down. Decent external roundovers rarely go amiss though.
7/ Depends on what other reflection boundaries are nearby. Assuming 1/2 radiation space, i.e. a floor & no other boundaries, it's doubled the size of the terminus.

PJN 19th January 2012 04:13 PM

I had a pair of them in a MLTL that I was using for a 2.1 system for my TV, they sounded fine, went down to ~ 60 Hz. Eventually I put them in much smalled sealed boxes crossed to the sub because of size constraints and thought they sounded better sealed when relieved of the bottom octave. Better mids and highs. Still using them for my TV, sound way better than they should for the cost.

PJN

VEC7OR 19th January 2012 05:19 PM

Thanks Scottmoose, this is what I was hoping to hear.
1) Reasonable as in loud enough for some relaxed listening.
2) Thought so.
3) In other words it isn't woth it, you can't urge (trade sensitivity for extension) an undesized horn to play correctly. Oh and if I do want to damp it, how should it be done ? For example some zig-zagging on the surface or some solid absorbent material ?
4) Check.
5) Hehe, just trying to sqeeze the best performance and learning what else is out there.
6) That makes sense.
7) I guess it all has to do with acoustic impedance again.

The only issue I see with TABAQ - if I build them taller - that means raising the port from the floor and loosing some extension, perhaps moving the port to the back and placing them near the wall will help ?

Scottmoose 19th January 2012 05:49 PM

Not a problem.

Still doesn't really mean much as everyone has different definitions of relaxed listening (some find Metallica's live S&M album relaxing), & the space comes into play. Winging it to assume you mean relatively undemanding material without large LF dynamic swings & the room isn't a barn, probably.

I didn't say that. Most back-horns are compromised & rely on QW action to prop up the LF below the point at which they are impedance matched. Done carefully, many people are happy with the results, especially if they are designed to use the room's reflection boundary conditions (1/8 space & 1/4 space loading). They just aren't impedance matched down to Fo, & therefore you need to pay attention to damping them, or reducing these effects in other ways. How you would damp it, as you would expect, depends on the specific design, so there is no one-size-fits-all answer to that I'm afraid. Would that there were. Usually I would suggest avoiding overly rigid materials since their absorbant properties are insufficient. I'm not too keen on foam either. Acoustic fiberglass, dacron, thick carpet underlay, ultratouch etc. are all effective when used sensibly.

Re the TABAQ, I presume you mean add a cavity under it to lift them up, right? Shouldn't be too much of an issue. I doubt you'd loose much in the way of LF gain per se, but the details of the response will alter somewhat. Exact cabinet location is usually a matter of experimentation, since the room dominates below ~300Hz (give or take).

Bjohannesen 19th January 2012 06:18 PM

I know some TABAQ builders have made an extra "foot" and filled it
with sand with great succes.
I have simulated this wiht MJK's models and you will loose a little LF.
Note that the port is the last part of the line.
You can fold the line with the port as the last part of the line.

VEC7OR 20th January 2012 08:20 AM

By relaxed listening I mean some bossa-nova, lounge and what not, room is roughly 5 by 6m.
For now my interest in horns had subsided, its a bit too broad topic, I just don't have the time to invest in it right now.
As for TABAQ - yes I'm planning on making them a bit taller.
My W4-1320 have arrived yesterday so its time to burn them in a bit.


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