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11-10-2022

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N-set
Gdansk, Poland
Posts 617
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
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11-10-2022

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Paul S
San Diego, California, USA
Posts 2,672
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

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rowuk

Germany
Posts 454
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

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Romy the Cat

Boston, MA
Posts 10,183
Joined on 05-28-2004

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

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N-set
Gdansk, Poland
Posts 617
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
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11-17-2022

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anthony
Posts 338
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

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N-set
Gdansk, Poland
Posts 617
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
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11-22-2022

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Edgar=
Posts 29
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.

03-01-2024

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	289
Post ID:	27343
Reply to:	26984

Drum and base

I recently had a visit by a close friend, who is an accomplished modern jazz saxophonist but a recording/mixing engineer, running his own small studio. We listened to some bass-heavy material on my Dannoys, the bass was acoustic - piano and drums. Damn good bass, damn good. I want more of it. I'm slowly coming back to the idea of a passive radiator sub to match the complicated phase behavior of PR in Dannoys. Sth like this:

1. 40+Hz sealed box with 2x10" ScanSpeak
2. One Scanspeak active, one is passive
3. Dannoys go unfiltered not to mess with its beautiful bass
4. Subs low passed somewhere around 60Hz to be determined exactly

Any thoughts? Hopefully the subs would reinforce the Dannoys rather than interfering with them because of the similar phase pattern at LF. My knowledge of speakers is poor, do you know of any software when I could simulate such an arrangement before building? There are lots of programs to simulate sealed/BR boxes but haven't found one for passive radiators.

Cheers,
Jarek
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03-01-2024

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Paul S
San Diego, California, USA
Posts 2,672
Joined on 10-12-2006

Post #:	290
Post ID:	27344
Reply to:	27343

The Ears Have It

Jarek, I have waited for some time for someone to advance a theoretical solution for your situation, as the problem you pose has been advanced repeatedly here for some time now. One might think about putting the PR on the opposite side of the cabinet, but according to theory even this would be +/- a one note solution. Someone, please put me right on this. Not sure about your turnaround time for boxes, but you might just have to test ideas and track audible results in your own space, yourself.

Anyway, nice that you have something you like to start with. So, don't mess with that, but make sure you can get that back any time you want to.

Best regards,
Paul S

03-05-2024

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Romy the Cat

Boston, MA
Posts 10,183
Joined on 05-28-2004

Post #:	291
Post ID:	27346
Reply to:	27343

I do not know

Jarek, I know exactly how you feel. There is some magic in 10 Read loaded passively to ScanSpeak SD1 motor with paper cone. The ScanSpeak with this semi-rubber suspension are not the neutral drivers but they have very pleasant, at least ty my ears, very nice, enriched with second harmonics distortions. This distortion with a puffy resonance at 50-70hr somehow sucks out the colored nature of the Tannoy red woofer and it all together works very nice, particularly for non-complex music. I worked sensationally as a prototype project and that had huge impact over me. As a prototype project you close your eyes to multiple shortcomings, and you feel that when this prototype going to be rendered as and final solution the shortcomings might be overcome. It did not happen in my case, at least in context of the efforts that I spent. I never succeeded complemented with more significant base and I never was able to make it to play loud. Elso, I failed to calculate the very precise size of enclosure necessary to make all the system work properly. Generally speaking, if you have a very very small listening room and very up-close position, and if you still do not play very loud then it might be wonderful near field monitor. Use the existing 50-70hr resonances and do not go deeper. If you're willing to expand simple red-ScanSpeak combination, then you are in your own. I absolutely failed on it and you are in unchartered territory. If you do find something that work, then please let me know. Saying all of it, I had a spectacular trophy from my parlay into the Tanoy saga. I use Red 10 tweeter with completely disconnected woofer as a reader for my main system, driven by Milq. I cannot express how stunning it is and that is absolutely the best that I ever seen in context of my playback.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

03-06-2024

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	292
Post ID:	27347
Reply to:	27346

Exactly!

Romy the Cat wrote:
Elso, I failed to calculate the very precise size of enclosure necessary to make all the system work properly. Generally speaking, if you have a very very small listening room and very up-close position, and if you still do not play very loud then it might be wonderful near field monitor.

That's exactly what I'm doing. I have a small room, walls close to the speakers, big sofa, etc etc. Recently I moved my seat even closer than it was so now the head is about 2m from the tweeters. To my surprise it did not spoil the coherence. I also attempted that Sumiko speaker placement method. Was quite caricatural in my case as I cannot move the speakers much due to the constraints and the changes were rather small but I did reach some interesting point where the sound was definitely louder and cleaner. Playing Bruckner 8 by Wand (Harmonia Mundi LP), I could touch that madness that struck me when I first heard that LP through my Stax chain. I did not experiment with the volume either, sticking to your initial recipe. I only added 10cm mineral wool at the back wall and 20cm at the bottom (almost covering behind the ScanSpeak) to decrease the MF output through the PR. I did not detect anything re the base extension and measurements were rather unreliable, but the MF output was gone. The main motivation to look for the base extension is my hope to add some "LF breathing" and add spaciousness to the sound. 2nd motivation is add more of that "motor", the driving force of an orchestra. The idea sis to add a woofer with the same Scanspeak PR to match one to the other. Stacking PR woofers seems doable, REL shows it with one of its series for whatever it's worth. Another idea to open up the sound is to add a supertweeter. There are Fostex with big alnico magnets.

Paul, my turnover times are only a bit shorter than changes in the catholic church, so I'm looking for a modelling tool first. Looks like I've found something- WinISD. Fortunately PR's are quite popular now, so there is some information on the web. I don't think I'm buying the one-note description of the PR.

Cheers,
Jarek
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03-07-2024

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Paul S
San Diego, California, USA
Posts 2,672
Joined on 10-12-2006

Post #:	293
Post ID:	27348
Reply to:	27347

Look before you LEAP

Another tool used by sound pros is LEAP. The guy who designed my BassZillas (some time ago) used this tool to make the most of a BR enclosure. As for the Fostex (U)HF, the pros tend to correct them digitally, as they need "something". Mainly, did you miss that Romy removed his RAAL super-duper UHF when he put the stock tweeter from the Tannoy on his stack, and he has just purred about this tweeter. The Visaton TL16H I use has a long, fairly flat tail, and it seems to work fine with a simple, passive X/O, if (more) UHF is still wanted after LF is fixed to your taste.

Nice that you scored that LP! Any good compared to the CD?

Best regards,
Paul S

03-07-2024

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	294
Post ID:	27349
Reply to:	27348

Supertweeter

Thank you Paul! Yes, I did notice Romy's tweeter movement, he also described it two posts ago. But I have a different room than him (smaller, dead, close walls, etc). I like the HF a lot, esp. with Ortofon cartridges, but I'm missing some air. Can supertweeter help with that? No idea. Anyone?

HM B8 LP - I don't have the CD version, so that LP is my only reference.

Cheers,
Jarek
STACORE

05-10-2024

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	295
Post ID:	27373
Reply to:	27343

Towards Dannoy bass

I laid my hands on WinISD speaker modeling tool, which seems to be quite popular and widely used. It can model passive radiators too. Here are the simulations of my idea of the Dannoy bass: Scan Speak active + Scan Speak passive in the same box as the Dannoys (89l or 37Hz). The amplitude graph (unfiltered) shows the "Dannoy rise" around 50Hz:

The simulated (unfiltered) phase shows two characteristic for PR phase jumps at Fs and F_box:

For comparison here are the actual measurements of my Dannoys in my room. To be honest, everytime I measure I get somewhat different plot so no idea how reliable that are:
Sample Dannoy LF response.jpg

But: 1) the phase discontinuity around Fs is there like it should 2) The second phase jump is at 30Hz rather than at 37Hz, which is due to Tannoy Red driving the box, not the Scan Speak as in the simulations above 3) there is a phase jump at 60Hz (persistent at all measurements) which i'm still scratching my head what it is.

The goal is to match and reinforce the Dannoy bass without spoiling it: Dannoys run unfiltered, the Bass 4th order cut at some 50-60Hz.
Gentlemen, what do you think? Will it match or not really? Any comments?

Cheers,
Jarek
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05-10-2024

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	296
Post ID:	27374
Reply to:	27373

Follow up (adding a lowpass filter)

And here is the same 37Hz PR box but with added 4th order Linkwitz filter at 60Hz:

I'm confused as adding the lowpass filter gives quite a different phase behavior, without the characteristic twin phase jumps:

Any comments much appreciated.

Cheers,
Jarek
STACORE

05-11-2024

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Romy the Cat

Boston, MA
Posts 10,183
Joined on 05-28-2004

Post #:	297
Post ID:	27375
Reply to:	27374

I am sorry, if you find anything, please, let me know.

N-set, I am sorry, I cannot be helpful to you in all of it. I got a spectacular sound with Red as is and one passive radiator in that given box, and I never was able to reach anything close to it with all my later attempts. I did some measurements, but they all did not make sense to me. Trust me, it gave me 2 years of headaches trying to figure out why it was such a spectacular result initially. If you went to experiment in this direction, you are on your own, sorry.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

05-11-2024

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	298
Post ID:	27377
Reply to:	27375

That's ok

I was just wondering if these graphs would tell anything meaningful to anyone. I have unfortunately very low experience with a speaker design.
One problem reported by Romy was a bass integration. The main suspect was the quirky PR phase behavior. My idea is to use PR bass but driven with
ScanSpeak.

Cheers,
Jarek
STACORE

05-22-2024

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	299
Post ID:	27397
Reply to:	27374

PR sub 1st order filtered

Amplitude:

Phase:

Simulations cost nothing, so I continue my a bit random walking and played a bit more with a PR sub idea, inspired in some way by Romy's latest discoveries in the midbass region and its influence on the Sound. I do miss good bass with my Dannoys despite listening near field. I want more charged sound, more LF spatial information, more of that big orchestra "drive". Above is the same idea as few posts back: 2x ScanSpeak 10", one active, one passive, same 89l box as Dannoy but crossed 1st order Bessel at 40Hz. The double phase flip is back for what's its worth. No idea how this might sound, 40Hz 1st order is sort of pushing the Scanspeaks to work well into 100Hz region. One option is what Roman suggested - getting a cheap car boombox enclosure, whatever amp and playing. However understanding what's happening would be nice too. Anyone knows good speaker fora to learn from about technicalities?

Cheers,
Jarek
STACORE

06-19-2024

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N-set
Gdansk, Poland
Posts 617
Joined on 01-07-2006

Post #:	300
Post ID:	27422
Reply to:	27397

Bass analysis continued

I'm going around with the Dannoy bass augmentation like, as we say in Polish, a chicken with an egg. I posted my problems on DIY audio and managed to get some interesting comments from a gentleman named Art who was kind enough to educate me a bit. Here is what came out of the discussion:

0) To set the terminology, what I want is augmentation rather than extension per se as I wanted to run the Dannoys unfiltered (no high-pass filter) not to affect its wonderful bass.

1) The wonderful bass can, in part, be a result of the bump in the 50-70Hz region, sth that Romy also mentioned. The guy called it "loundness contour" and suggested that in order to properly augment it, I need to keep the bump down to some 30Hz (based on my mean field measurements):

Dannoy bass extension analysis.png

2) Getting +25dB @ 30Hz seems monstrous but the Fletcher-Munson curves come to help: the perceived loudness increase at LF costs much less dB than at higher freq. Perhaps even as low as +3-4dB can help
3) The integration of a PR design with a woofer should in principle be not more complicated than a ported design and the complicated phase response at LF should not be problematic (in principle)
4) My idea of a PR woofer (1 Scanspeak active + 1 PR) looks weak as the PR speaker will reach max excursion very quickly. So looks like a sealed box or a ported one is the way
5) Sth I did not understand: Art kept insisting that I did not present any arguments that I need augmentation. My arguments of a sonic nature (the sound of big orchestras misses the size and impact on LF + missing LF spatial information) and a physical one (a single 10" cone simply cannot produce any appreciable SPL below 50-40Hz) and the measurements were not convincing. No idea what he meant, he then lost interest in the thread.

The discussion is here: https://www.diyaudio.com/community/threads/adding-low-bass-channel-to-a-passive-radiator-design.413147/#post-7700542

So at the moment looks like I'm gravitating towards Romy's original bass design from old Macondo: 2xScanspeak 25W/8565-00 in a sealed box of Fb=39Hz (~90l) This is about max size I can try fitting in the room. If I hang them by the ceiling (getting +6dB boost), there would be around 70cm path difference between the Dannoy and the woofer to the listening position, so I guess a delay of 2ms the woofer would be needed.

Cheers,
Jarek
STACORE

Page 15 of 16 (303 items)

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	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	686870	07-29-2007
»	New	Dannoy 2021 Loudspeakers..	It is all bout me....	Audio For Dummies ™ Forum	24	36380	08-04-2021
»	New	Bermuda Triangles of Audio..	Tannoy carton issues...	Playback Listening Forum	5	13153	11-09-2021