Beautiful Swingin' Speaker

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
I knew that you would build something like this! Great work, and great inspiration for all of us! :)

:snoopy:



########


With *your* thread you show and encourage us to consequently follow our ideas to the very bottom end – I'm really thankful for the great fun we all have had there !

I'm looking forward with which final rig you'll come up with.
:)

Michael
 
Good job, and thanks a lot for sharing:D

...

P1230126.png


P1230128.png

...

I got 2 questions:

1. Smart and clean solution for woofer! How is the acoustical effect of the gap? Is there any detectable 'leak' on LF?

2. The top-bottom walls of dipole horn seem horizontal and parellel. Would there be internal reflection? (Worrying about the non-flatness of wavefront... )

:)
 
I got 2 questions:
:)


Two good questions but no "real" answer, I'm afraid :(


1. Smart and clean solution for woofer! How is the acoustical effect of the gap? Is there any detectable 'leak' on LF?

Thanx for your kind words.
I have not measured – so I cant tell the accurate difference.
From listening I'd say there isn't too much a difference – I still have my active turn down shelving (!) around 45 -80 Hz in place – otherwise there's simply too much bass (well, in that room)
Also – there still is this physical sensing of the bass through the floor by my feet. Given the exceptional good isolation of swings regarding leakage path through the structure, this tells me at least something ;)

This physical sensation through the floor I like a lot and is something I'm always after – its not that the carpet builds up in waves – but it has to be there – even at moderate levels.



2. The top-bottom walls of dipole horn seem horizontal and parellel. Would there be internal reflection? (Worrying about the non-flatness of wavefront... )

Yes, top and bottom plate of *this* dipole horn are in parallel to simplify building and to keep inter driver distance low.

If we assume ideal flat wave front to exit the NEO3 and enter the horn – well, all vertical pressure points are in perfect balance to each other – so no reflection = "bouncing between top and bottom plate" should occur IMO.
On the other hand, with such a design, there is always the issue of "in-adequate termination" = extreme bending of the wave front = sharp 180deg diffraction - where the top and bottom plate ends.

This issue could be treated either in applying the horizontal contour in the vertical direction too – making up for a standard horn – or by figuring out a lip that provides smoothing the same way as rectangular OB provides smoothing over a circular OB.

As a standard horn isn't an option for me right now (I encourage everybody to give it a try !) I did some investigation in optimizing the lip with reasonable results – in *FR measurement* at least:


NEO3-W in Gaussian Min Phase horn with optimised lips:

polar_0_10_20_30deg_smooth.png



NEO3-W in Gaussian Min Phase horn with straight lips:

non_DPRW_polar_0_10_20_30deg_smooth_text.png




sadly these improvements in FR measurement do not correlate with sonic impression.
Or maybe I should put it more precisely – flatter FR here is a trade off to increasing group delay – which is not handled easily with simple passive XO.

Bottom line – the straight cut at the end of the horn sounds really good to me – though it measures not as perfect as I would have liked.


Just for comparison
below the Neo3-PDRW (the one with the two inner felt stripes at each side) in the same Gaussian Min Phase horn with straight lips:

polar_0_10_20_30deg_smooth_text.png




Michael
 
Last edited:
This issue could be treated either in applying the horizontal contour in the vertical direction too – making up for a standard horn – or by figuring out a lip that provides smoothing the same way as rectangular OB provides smoothing over a circular OB.

Michael

Hi Michael,

Have you sketched out any HORN LIPs which use the contours you have been working on? 90 x 40 constant directivity horns are popular for 1" compression drivers since they mate well with 10" midbass cone speakers.
 

Attachments

  • Elip_horn.jpg
    Elip_horn.jpg
    23.3 KB · Views: 591
Last edited:
1/3 octave is too coarse. Nearly everything looks good in 1/3 octave. Can we see 1/24? How long is the impuls from which the frequency response was derived?

polar_0_10_20_30deg_smooth.png


Best, Markus

Markus I don't like to go into the details of this specific make for the same reasons as already posted – its not finished - and I am working in a different direction now - a three way variant with the same (the unmodified) B&G NEO3 horn but nude drivers, which I find very rewarding – in fact – pretty inspiring on a completely different matter....
Added mid speaker will be the Selenium 8W4P - an incredible piece of sound at very moderate cost...

The horn you are interested in has been a two hours of fun tweaking with hot melt glue and some wood I had laying around to see what I possibly can get by modding the original horn.
Sadly, auditioning then revealed too much of a guttural tone that the simplistic passive XO could not handle.
But anyway - I'd encourage you or anyone else to build what I outlined and then do some creative work on the lips and see how far you possibly can get
;)

Generally, I agree that a 1/3 octave measurement is to coarse – as is the indoor windowing of ~3-4ms - but please have mercy – I'd like to have some comments of people first about their auditioning experience beforehand without to much prejudice.


Michael
 
Last edited:
harsh evaluation

yep... the"pros"always take pot shots, unless it's "their" data... then it's pristine and beyond reproach. I was taken to task as posting irrelevant data a few years back, when all I was interested in was an assesment of the >600 Hz region... for my BG RD-75 dipoles which pretty much ruled out the 'room" effects, given the windowing

An externally hosted image should be here but it was not working when we last tested it.
 
This is an interesting project - I'm particularly interested in seeing the vertical polar response for the Neo3 horn. Personally, I don't buy the argument that one axis matters more than another - after a few reflections, it all arrives at your ears the same.

My guess, in lieu of more data and listening comparisons, is that while a horn allows more LF output from the tweeter, it makes the off axis response rougher. Pick you trade off, it seems...
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.