[JoshK]

less talky more pics   

Yeah I know.  Nothing significant to show yet, but need to take a couple picture to document how my feeble attempt to veneer is going.

My work schedule lately hasn't been leaving much room for me.  I don't think it is changing any time soon. 

[JoshK]

I wouldn't give 'the mound' a second thought. I think you generally see something similar in every axisymmetric horn/waveguide, and you get rid of it with a notch filter or finagling with the crossover -- I've seen it handled both ways.

Regards,
John

I guess what I had intended to say is that once you add in the CD Eq you can probably gain some usuable lower bandwidth.  Maybe, maybe not.  We'll see.

For the top end, if 14khz isn't high enough or the breakup is objectionable, you can always throw one of these into the mix.
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=294-580

The comb filtering is likely not to be objectionable at these frequencies (i.e. >7-8khz)

[JDUBS]

I still want to hear your Unities.  Your welcome to come hear my setup when it gets rolling.

You have a DEQX as well, so I think we have many things in common in our systems.

Josh, as soon as I get my speakers set up, I end up tearing them down again with new (bigger) plans.  I'm glad I have another (but smaller) setup so I can at least listen to music in the interim.  I'm now rewiring the Unitys with Jena wire and 3 inputs going direct to each driver (or set of 3 in the case of the midrange drivers).  Also have a pair of Lambda 15" woofers to swap in place of the Yorkville 15s.

I definitely want to get your input, so as soon as I can get this setup up and rolling (again), I'll have you over.

Looking forward to hearing your setup, too.

-Jim

[JoshK]

Jim,  which version of the lambda woofers are you going to use? 

I just got my Eighteen Sound ND1460As today.  Now if I only had the waveguides. 

[JDUBS]

Josh, I have a pair of TD15Xs.  Got a good deal from a guy on diyaudio.  I dry fitted them today and they seem to fit fine in place of the Yorkville 15s. 

-Jim

[JoshK]

ok, so an in progress pic. 



You can actually see the MT in the background in its current state (primer on baffle + raw sides).

[JoshK]

Putting on the last pieces of veneer, the chamfered sides.  Then it is onto practicing with anoline dyes.  The goal is a bombay mahogany finish.  There are a couple of places where I dripped a little glue so it is going to be a challenge to get it looking perfect.

[Pez]

Nice Josh. Put a compressor in there and you've got yourself a nice hybrid mini fridge. 

[JoshK]

Indeed they are big.  Its all about Hoffman's iron law.  If you want bass and you want efficiency that spells a big enclosure, no way around it. 

I am now at the point of experimenting with aniline dyes on a piece of the left over veneer.  The goal is a bombay mahogany finish.  I have a bunch of transtint dye colors.   I need to find something to measure out small mixtures in the same proportion as the final mix will be.

Once dyed, then goes the shellac.  Fortunately, I've done this before.

On another note, I've been in talks with Jeffrey Jackson of elevenhorns.com.  I am working on a design of a large OS waveguide with LeCleac'h mouth termination.  Its been done before, look up min phase waveguide in Germany on diyaudio for an example.  When I started I hadn't noticed it was done before, but oh well, I am not looking for fame. 

My intention is a full mouth for <= 800hz support.  This will be a large waveguide and when designed, Jeffrey is going to have it crafted out of Mahogany.  I have an estimate already so it is likely to go ahead.

My MTs will likely become surround duty, but we shall see.

[JoshK]

For bass....you mean that those bins aren't bass?  Well they are woofers, as in mid bass down to 45hz, but for subs...I am going to build up to 4 of these:



Pictured above, is the 38hz TH.  I may build two of these and two of the 30hz TH.  I haven't decided yet. 

The idea is distributed bass like the Geddes solution with tapped horns of reasonable size. 


The link to volvotreter's THs
http://www.volvotreter.de/th.htm

[JoshK]

Here is a link to eleven horns showing the different wood finishes:

http://www.elevenhorns.com/600LC.htm

That is the same wood in all pictures shown.  It is Phillipines Mahogany, the darker ones are just dyed/stained.

(I have no association with elevenhorns, I have just been in discussion with Jeffrey, so I know a few things not on the site.)

[nullspace]

On another note, I've been in talks with Jeffrey Jackson of elevenhorns.com.  I am working on a design of a large OS waveguide with LeCleac'h mouth termination.... My intention is a full mouth for <= 800hz support.

That sounds awesome! I'm really looking forward to hearing more about those. Are you getting them made to match the exit flare of a specific driver?

Regards,
John

[JoshK]

Yes, I made the profile to fit my Eighteen Sound 1460As.  They have a 10 degree exit angle.  My spreadsheet solves for whatever exit angle the user puts in.   Dennis' spreadsheet and JohnK's do too iirc. 

I had played with the math some time ago as fun and practice and realized there was an actual closed form solution to the throat angle correction.  Based on that I edited the spreadsheet accordingly. 

I've been playing around with the spreadsheet over the last week to add a full 180 degree mouth roll back.  Currently this roll back is pure circular.   I'd like to have an option for a LC roll back.   I am not convinced that this roll back adds anything special over a circular one but it does make it slightly smaller, or so is my estimation thus far.


This profile is also not based on simulations.  It is just a common sense solution.  Take the OS profile which is CD and minimum diffraction and add to that a contour that provides a smooth transition to free field. 

[nullspace]

Jack Bouska came to the same conclusion as you, in that a non-circular roll-back makes for a smaller horn. Jack went with Tractrix: HERE.

Before I bought my horns, I was fiddling with one of the spreadhseets floating around and had a profile for a 60deg OS with Tractrix roundover -- it was huge.

Regards,
John

[sts9fan]

The size of those subs is very attractive.  Do you plan to use the TangBand drivers?

[JoshK]

The size of those subs is very attractive.  Do you plan to use the TangBand drivers?

Yeah, I bought 4 of them.  They are easy to hide behind a chair in a corner. 

[sts9fan]

If you were to only make two would you go for one 38 and one 30?  These seem perfect for me.  Thanks for posting.

[JoshK]

I'd go for the two 38hz if I were to make two.  The 38hz ones go higher, up to 100hz or maybe a little more.  But they drop off below 38hz.  What is more important, the low end or the higher end?  And what about size?  The 38hz ones are more compact.

[sts9fan]

Well I have a gr servo sub that cam go real low and pretty high.  I guess it depends on where I want it to deal with.

[TRADERXFAN]

I think you would be better off using the sealed servo as the ULF, because the servo will definitely be accurate down to the 20's. And  then used the tapped horns as the BB in the Geddes multiple sub approach to reach up higher. I take it the tapped horns would have a good acoustic highpass on them?