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  »  New  Macondo's Axioms: Horn-loaded acoustic systems..  A link to another thread....  Horn-Loaded Speakers Forum     120  607422  07-29-2007
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11-10-2022 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 605
Joined on 01-07-2006

Post #: 281
Post ID: 26984
Reply to: 26982
The conundrum
 Edgar= wrote:


N-Set, I invite you to make your own recording of the phase of your Dunnoy. I used my phone camera to do it and a free online sweep generator. I had Tannoy, Scanspeak and laptop screen all in shot when I filmed and shot from as side on as possible. I didn't observe another phase flip like you mention below 20hz. Definitely out of phase from 1hz to 20hz.

Edgar, thanks for the tip, hope my antique phone has a slow motion mode. I'm only learning the PR operation. The two phase jumps can be seen on simulations here :

https://www.facebook.com/groups/DIYLoudspeakerProjecPad/posts/646526432369864/


 Edgar= wrote:
If you do film your Dunnoy you will get insight into the conundrum of integrating more bass. I'll give you an example. For the sake of this argument let's pick a design frequency of say 40hz to crossover. When I watched my footage I observed the phase drift start around 55hz. Im calling from 55hz and up, in-phase and from 55hz down out-of-phase. It's not technically in phase yes, also it not just suddenly out of phase either, and for that matter it doesn't start at 55hz but there is an observable shift around there, both visually and acoustically enough for me to choose that frequency for this argument.So at 40 hz what driver do you want to interface with? That is which driver do you want to time align with? If we choose the tannoy then we will be out of phase with the PR. If we choose the PR we will be out of phase with the Tannoy. As we go lower and the difference of phase between active and passive radiators increases, the issue gets worse. Which ever way you cut it, if you add another driver to your room delivering sub 55hz energy, it will be out of phase with Dunnoy.


I get the conundrum. Thinking out loud, I have two ideas (feel free to criticize):

1. Align the bass channel with the active driver. PR is working out of phase with the active driver anyway.

2. Make the bass channel with its own SS PR (say 1 active + 1 passive SS), the same box size as the Dannoy to make the PR work under the same conditions.

In both cases Dannoy works unfiltered as high passing seems to destroy its sound (I haven't tried myself yet).




Cheers,
Jarek
STACORE
11-10-2022 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,517
Joined on 10-12-2006

Post #: 282
Post ID: 26985
Reply to: 26984
"PR"
When the passive radiator in question is mentioned, are we sill talking about a particular active 10" Scanspeak driver that is not hooked up to an amp? Again, the PR is always parasitic, more or less fighting with the active driver, except, apparently, at its own "Fs". Wouldn't another PR do "the same thing" to the LF array? Who needs more drag on the active LF drivers, with the PR flipping phase and shutting down the LFdown low? Not sure, just based on an abrupt 180 phase shift, how to tie the top of the LF array with the bottom of the Dannoy/Dunnoy.


Paul S
11-11-2022 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 435
Joined on 07-05-2012

Post #: 283
Post ID: 26986
Reply to: 26983
That matches the behaviour of many musical wind instruments too
Interesting video. It is a compelling argument for open back, infinite baffle or transmission lines designed to completely absorb the back wave. Everything else simply works much differently than we want to believe...


Whenever I feel blue, I start breathing again.
11-17-2022 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 10,042
Joined on 05-27-2004

Post #: 284
Post ID: 26987
Reply to: 26391
I have no clue
I do not know what is going on. A couple of days ago I turn playback and decided to play I very much non-demand material and with suddenly the sound I ever heard. I do not know what is going on. I am slowly contemplating the idea to bring horns back to rotation. 


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-17-2022 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 605
Joined on 01-07-2006

Post #: 285
Post ID: 26988
Reply to: 26987
What sound?
What sound? With Remedies or horns? Funnily enough, a few days ago I played via Dannoys my heaviest cannon - Decca London Reference +FR64S all silver wired, Charcroft Z-foils etc etc. Big symphonic music, not particularly my favorite but... it was damn, damn good! I was surprised by the big sound Dannoys produced! 
I'm still thinking of the subs but first the preamp and few quick & simple tweaks to test: 1. add a bit of loose rockwool filling to the boxes. i suspect that some MF energy coming out of scanspeaks are actually box reflections 2. 4mm felt around Reds to somewhat kill the reflections from the front panel 3. QRD diffusers on the ceiling   


Cheers,
Jarek
STACORE
11-17-2022 Post does not mapped to Knowledge Tree
anthony
Posts 335
Joined on 08-18-2014

Post #: 286
Post ID: 26989
Reply to: 26988
Some distance
 N-set wrote:
QRD diffusers on the ceiling   

QRD diffusers need distance to work properly that you are unlikely to have at the ceiling.  BAD panels or better yet the convex type diffusors are probably better options.
11-17-2022 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 605
Joined on 01-07-2006

Post #: 287
Post ID: 26990
Reply to: 26989
Good point

Anthony, good point (as always from you). First, my initial thought is to avoid any absorption not to deaden the room more than it is dead now. Hence hardwood diffusers. Right or wrong, the experiments will tell. Second, I did a bit of research and found this rule in the diffusers' bible Acoustic Absorbers and Diffusers Theory, design and application,  page 37:

"Precedence has shown that it is best if the listener is at least three wavelengths away from diffusers."
The panels' I've ordered are 550Hz and up which gives minimum of 2.1m. I can do that (diffuser-to-listening-position) even in my small space.
Interestingly, on p.38 the authors even suggest that being as close as 1m away from a reflecting surface, it is better the surface is diffusive rather than plane.



Cheers,
Jarek
STACORE
11-22-2022 Post does not mapped to Knowledge Tree
Edgar=
Posts 26
Joined on 02-13-2021

Post #: 288
Post ID: 27008
Reply to: 26988
I am a moron
 N-set wrote:
i suspect that some MF energy coming out of scanspeaks are actually box reflections
Hey N-set, as I am back listening to my Dannoys and I listened again about a week ago for the passive radiator and found -
 Edgar= wrote:
The Scanspeak still resonates a lot of MF energy...
This statement is not the case. Not sure what moron wrote that, but it is not the case. 
It sounds like a black hole or like a window to the back of the box. I thought to myself "I can hear the inside of the box". It could be more delusion from me but interested to see what you find.
Page 15 of 15 (288 items) Select Pages:  « First ... « 11 12 13 14 15
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Macondo's Axioms: Horn-loaded acoustic systems..  A link to another thread....  Horn-Loaded Speakers Forum     120  607422  07-29-2007
  »  New  Dannoy 2021 Loudspeakers..  It is all bout me....  Audio For Dummies ™  Forum     24  21152  08-04-2021
  »  New  Bermuda Triangles of Audio..  Tannoy carton issues...  Playback Listening  Forum     5  7940  11-09-2021
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