Back horn design 4" drivers

[mattress67]

I'm looking at building a small back horn design speaker using Tang Band WD1052 4" drivers. I've seen a lot of pics on the internet with some pretty intricate designs, which is fine, but I can't find actual specs or patterns that I can duplicate (a nice way to say copy).


Two questions here for a noob.


1. Since TB provides a design for their 8" driver, can I just shrink everything down to a 4" design? (my gut says no).


2. If I decide to duplicate one of the more intricate designs, can I just best guess the series of curves that I see in the pics?


Thanks

 

[Godzilla]

I'd recommend considering a BIB if you plan to put the speakers into corners.

https://speakerprojects.wordpress.com/cabinet-types/bib-loudspeakers/bib-calculator/

I like BIBs because all the guesswork has been figured out and the results are always very good.

 

[Scottmoose]

Re the questions:

1/ No. Not in the vast majority of cases. Horns don't work like that. And

2/ No. Or more precisely, you can, but that doesn't mean you'll get anything usable.

For the driver, do you mean the W4-1052SD or the ferrite SDF model? Other than a BIB tapped pipe-horn, both should go straight into FH3 (Frugel-Horn Mk3 -that's not a typo BTW. ). Only thing you'd have to watch is clearance to the internal baffle with the SDF model given that big magnet.

 

[chrisb]

A spacer plate / supra-baffle is an easy way to deal with a deeper mounting depth or wider flange that might otherwise be constrained by the FH3's 140mm internal width. It can also allow swapping out of other driver models, should you be so inclined
A very detailed set of plans for the FH3 are readily available, and by now several hundred pairs have been built worldwide with a wide range drivers in the 3- 4" class

 

[sreten]

Hi,

Take a long hard critical look at :
http://www.quarter-wave.com/Horns/BLH_Design_Article.pdf

rgds, sreten.

 

[planet10]

...and by now several hundred pairs have been built worldwide…

Likely well over a 1000 pair by now.

dave

 

[mattress67]

First of all, excellent responses - thanks. And that one link whoa - this really is rocket science!


Anyhow, although I know I'd achieve better results with the BIB/FH3 design, I'm looking at something small - just a set of speakers for a very small area. Therefore I was looking at the designs for something a bit more compact (more so than even the one in the pdf) and something similar to the speaker in the Tang Band D4-1 speaker kit which is only about 16-20" high.


And I suppose my constraints might negate the practicality of a back horn design.

 

[planet10]

And I suppose my constraints might negate the practicality of a back horn design

Yes… it will no longer be a horn, even if so-called. The BIB is not size compromised, the FH3 uses wall/corner loading to shrink its size.

dave

 

[GM]

Smaller for a given set of driver specs = higher cut-off, more pass-band 'ripple', ergo more damping [stuffing] required; so often a double bass reflex [DBR] is a better choice overall if for no other reason than it's a lot easier to build.

GM

 

[Scottmoose]

'Desktop' & 'horn' doth not a happy combination make. If you want to get any LF out of it, horns have to be big. That's how they work. Compromising them down to desktop size is a recipie for poor performance. Sadly it's those laws of physics in operation.

 

[mattress67]

Right, and understood.


I'm looking at cabinet suggestions on the TB web site and they seem to have both back horn type (well, it looks like a rat maze) and ported speakers that are under 2'. Am I correct to say I should just stick to ported if under 2'. I'm also open to DBR design - simple provides greater incentive.

 

[planet10]

Can you post a link… the TB "horns" i have seen are not.

dave

 

[mattress67]

Pics

Here they are

 

[planet10]

That 1st looks like a horn, but is too small so it ends up as a poorly designed quarter-wave resonator.

I'm not a big fan of double reflexes. Because the Vas is large for a 4" an optimal reflex is about 16L, but you don't loose much going to 10L.

dave

 

[Godzilla]

What about this?

https://m.youtube.com/watch?v=ei6-1k4efig

Uzu-10III �݌v�}

 

[hm]

flute

an this? + sub below 90 Hz

 

[mattress67]

I appreciate the response, and the last two designs look decent, but not a whole lot different than the cabinet suggestion by TB. I mean, they're different, but we are still attempting to get a back horn design out of a compact design. And since sound is in the ear of the beholder, looks like I'm gonna have to build a few designs to optimize.

Thanks all (don't hesitate to add more suggestions!)