GoodSoundClub - Romy the Cat's Audio Site

10-22-2022

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Edgar=
Posts 29
Joined on 02-13-2021

Post #:	228
Post ID:	26917
Reply to:	26869

Experience with Dannoy

Howdy all,
I have been playing with the Dunnoy concept since Romy discovered it and I agree that it is a very good improvement for Tannoy bass.
Dunnoy with reverb injection is a phenomenal experience.
I have gold drivers not red but I tried both 10s and 15s in the Dunnoy configuration.
15s sound 4 times bigger than the 10s but the 10s mid bass is better (not surprising I suppose).
My observations is that the Dannoy concept makes an already very good wide bandwidth driver even wider. it pulls the Fs of the Tannoy way down without damaging its dynamics. It is a luxury to have such a big sound from such a small box.
Regarding bass integration, the passive radiator acts like a port in that it is IN phase around its Fs but OUT of phase below that. I found this makes adding another channel underneath challenging.
N-Set I think you will need to cross over waay lower, like around or below the Fs of the Scanspeak if your are considering a channel under Dunnoy.

After playing with the Dunnoy configuration I feel there are a few things I have to offer. First one is time alignment is still really important. Scanspeak should be as close as possible to the Tannoy driver and set back to try and have a similar acoustic centre. The Scanspeak still resonates a lot of MF energy and that needs to integrate that MF with the Tannoy. IMO the Tannoy does its magic because of the wonderful integration of the mid and high unit, the wonderful consistency of dynamics across the two units and over the xover frequency so I feel time alignment of the Scanspeak (or any other drivers in Dunnoy) is important. It's this reason I feel it is probably very difficult to add a mid bass driver to Dunnoy and have it be better. Adding more drivers to get bigger sound creates the problem of time aligning those drivers and that is not easy when the drivers are as physically big as they are and wide bandwith like these drivers are. Remember the Scanspeak is not filtered in this configuration.
If one needs Dunnoy to sound bigger I think going to a 15 is a good way to go. I strongly feel the Scanspeak needs to be the bottom driver as the radiator. The Fs is damn low so not much of a trade off. If one were to add more drivers to the Dannoy concept to have it sound bigger like adding the AK15 for example or adding more Tannoy drivers, I think the drivers need to share a common air spring so the Scanspeak can dampen both at the same time.
Personally I don't think adding more to the Dunnoy will achieve better. The combination of the two is amazing. Having bass like that from a Tannoy and it also being in a tiny box is just great. The way the Scanspeak rides the Tannoy to pull it way down without damaging the dynamics is a very enjoyable.
I also think reverb injection is definitely worth while. How bass hangs in the room with the reverb injection is just so inviting and attractive. Defiantly recommended.
Ed

10-23-2022

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	229
Post ID:	26918
Reply to:	26917

Yes!

Edgar, I completely miss you in all of your findings and I also was thinking about 15-in toy with a pair of sunspeak passive radiators. Indeed, Tannoys reinforced by sanspeak passive radiators is a magical configuration. I wonder do you drive them with Vfet amplification or not. You're finding that given configuration spin fhase at the bottom is also very accurate, I was trying for 2 months to add exceptionally well performing lower base to it, 15 Midbass driver and I never was able to have a result which would I recognized as improvement. I have a lot of open bottle array crossed at 20 cycles and it does complement Tannoys with Scanspeak but only in Audio sence. From musical perspective, in this configuration, lower base do not add anything. I do not know why but despite exceptional audio this lower base does not add to the system it's ability to conceive metaphors. The Tannoys with scanspeak is absolutely insane configuration which act in my perception as a gorgeous woman in stunning mini skirt which make my imagination to race and guess what is underskirt. Any lower base that I was trying to add to it act as addition of constructors boots to those gorgeous legs in mini scirt. It just acts as direct violation of aesthetics. My local audio friend Bill, who experimented in the same direction went into other direction and he replaced san speak with another possivly loaded 10 inch tannoy. It is very interesting proof but I would add not another passive Red but another active Red results Twitter and another passive one or to sanspeak. That kindness that sanspeak add to the bottom of Red in my view absolutely cannot be ignored. The only one shortcomings for that kindness that I was able to observe is that that kindness to come ever present and if music call for brutal force, dry and cold execution with insane dynamics then skan speak does it a bit more polite than I would like to. It might be fun to adopt Meitner IDAT algorithm and to make super transient and super dynamic signals handled by my Macondo and the rest by Dannoy….

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

10-23-2022

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

Post #:	230
Post ID:	26919
Reply to:	26917

Very interesting

Edgar, thank you for sharing your findings. The timing couldn't have been better as I have just re-assembled my Dannoys after months of idling (I liked the sound of Dannoys so much that I decided to put a hard wood parquet to add some sparkle to my room). I agree that the bass is absolutely gorgeous in the perceived extension and dynamics. It "makes it" for the Sound. Interesting findings about the lower bass. I didn't start any lower bass experiments due to the lack of time. Both your comments are rather discouraging. Perhaps better to invest time into a preamp idea I have been massaging for months.
Edgar, would you share details of the rest of your system (amps, pre, source, etc) and pics of your Dannoy realization? When you say SS close to the Tannoys, you mean along the vertical axis (I have about 39cm center to center) or the depth or both?

Cheers,
Jarek
STACORE

10-24-2022

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Edgar=
Posts 29
Joined on 02-13-2021

Post #:	231
Post ID:	26924
Reply to:	26918

It's hard to come back from the dynamic capability of horns to direct radiators...

The mini skirt analogy is a great fit. That is my experience.
Or maybe like that stunning girl has small breasts and one has know the joy of a good handful. There are ways for enhancement and while one could get more, the girl is no more beautiful and now a little less elegant...
Another tannoy with tweeter disconnected but the woofer driven, sharing a common air spring with other tannoy and scanspeak, i think might be worth trying. with this config it would be easy to dial in the second woofer with just a coil making adjustment simple. having the reinforcement lower where you want it but keeping out of the midrange making time alignment/integration a little easier/less critical. I could try something like this but tbh am am quite satisfied as is for now. I only have a small room and my aims are not terribly ambitious. I am quite satisfied living with the beauty in the miniskirt as she is...
I havent used Vfet and the rest of my audio system is nothing particular special. My analog source is not worth mentioning and for digital i'm running a Lavry DA10 and only on SPDIF so i am certainly no authority or particularly experienced in high end source units. I drive Dunnoy with a quite generic mid- century topology amp. Generic indirectly heated triodes up front and 4 x triode strapped pentodes on output. Not the most refined amp, very non offensive, a good compromise for reasonable power levels needed for Dunnoy.
I might be able to try the B2, a local guys has one not far from me.

10-24-2022

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Edgar=
Posts 29
Joined on 02-13-2021

Post #:	232
Post ID:	26925
Reply to:	26919

Howdy Jarek

My comments are rather discouraging arn't they! Not my intention but hopefully helpful in the long run.
Regarding time alignment i just wanted to raise the point i think it might be more relevant than initially anticipated by someone considering building this config. The scanspeak plays quite high and i hear quite alot of MF energy from it. This was offered in the context of the hit and miss results Romy and Bill had with Dunnoy, sometimes magic but sometimes not, and as a possibility, this might be relevant to that. Please know this is a strong suspicion for me and not something i have thoroughly tested. My suspicion arises from I felt I had better alignment with the 10 than the 15 as the depth of the 10 is closer to the scanspeak 10. I ran the 10 first and then modified the same boxes for the 15. The tannoy is mounted on the front of the box baffle and the SS on the back in an attempt t get acoustic centres closer. I am away but will send a photo through when I get back.
I would say horizontal time alignment probably more critical than vertical but they are both critical generally i suppose. You might be able to try mounting the SS on the back of your front baffle and see if you notice an improvement but i am not confidant it will be worth it, particularly if you are currently satisfied with what you are hearing. Or, given the distance between your two drivers you might be able to just quickly test if angling your speakers back and forth (adjusting the horizontal alignment of your drivers relative to your ear) alters your perception of the sound. quick and dirty test might help gauge the relevance for you.
I want to reiterate that what i like about Dunnoy is the simplicity of the config. Most people can find a tannoy, order the scanspeak, find a box, slap them in and just like that you will have an outstanding loudspeaker. Very small box relatively, wide bandwith, sophisticated dynamics and very good tone. To get better or more would require a LOT more work, and look something like Macondo i imagine.
Hope that helps.
Ed

10-25-2022

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noviygera

Chicago, IL
Posts 177
Joined on 06-12-2009

Post #:	233
Post ID:	26926
Reply to:	26918

Large Tannoys with strange passive radiators

I think I wrote In the past here, if you like the 10” Tannoy, why not try the 12” or 15”? The ones with rubber surround are not so good in my view (from CPA or DMT series as they have very restricted midrange) but the cloth surround Tannoys are worth a try for sure. On a budget, the 12” ceiling Tannoys are sometimes for sale on eBay for not much money.
Another strange thought, but I have not tried this, if you like the sound from your SS passive driver, maybe connect the terminals of the SS and drive the input of you subwoofer amp with the passive SS? No idea if this will work so do not make an idiot out of me more than necessary. Good luck to the subwoofer amp.
Also I would not mind to try any soft suspension 15” vintage driver as passive radiator, no one said the SS is the only appropriate driver. Possibly, even the a Tannoy 15” with rubber surround (it way work well as a passive radiator only) but remove the tweeter. As a result you will have a port in the center of the cone while the cone acts as a passive radiator. This is where I’m willing to be congratulated being an idiot, but this just may work, completely unpredictably.
For improvement of time alignment one can try mounting the SS radiator not on front or back of cabinet wall but top or bottom or side.
In other words, I think there is more to try here, mainly other larger Tannoys.

10-25-2022

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

Post #:	234
Post ID:	26927
Reply to:	26925

Living with small breasts

Haha, great analogy Edgar! Actually while writing to you the previous mess, I was listening Dannoys the 1st time after laying down the parquet and that was sooo damn good! No idea if the parquet helped or what but it was mesmerizing (FM program with both recorded baroque music and live broadcast of contemporary). The sound was like sitting a bit deeper in a music hall, as opposed to front rows where everything is spitted in your face for good and for bad. Since I have a small room, that gave a slight hallucinogenic feeling as the sound (recessed position in a music hall) did not match the picture (my small room). So I can definitely live with small breasts and would rather spent the little time I have for audio on more important things down the chain than the subs.

Cheers,
Jarek
STACORE

10-25-2022

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Paul S
San Diego, California, USA
Posts 2,657
Joined on 10-12-2006

Post #:	235
Post ID:	26928
Reply to:	26927

Repeating Accidental Success?

No idea how one blends in a random passive radiator, and I gave up on it after a year or two, many years ago. But if you can put your ear to the passive radiator and hear it plays up into the midrange, then you will probably want to use something with tone. I imagine there is the provervbial synergy between the particular version of the 10" Tannoy Red and the particular 10" Scanspeak, also the boxes that Romy happened to have on hand when he concocted the original speakers in question. So, are others looking for this same synergy, or a synergy of their own device? As far as using "similar-but different" drivers, the larger Tannoys do have a more "full" lower-mid sound than the smaller ones, for better or for worse, but they also, obviously, have a bigger jump from the cone fundamentals to the tweeter, as well, and the various drivers do sound different, one from the other.

It seems from following these threads that no one so far has been content to stay focused on recreating the accidental success of the original Dunnoy/Dannoy. Is this because no one can actually recreate the original, or is it because everyone has issues with these speakers that they'd prefer to improve on? For instance, don't we always say that one wants 20 dB headroom. Does this mean people are happy listening at 70 dB, or does it mean that something about the Danoy "offsets" the need for headroom? I still can't figure out how you can push the Red down to 50Hz with the original configuration and also get the headroom? While multiple Red drivers sans tweeters "sounds logical", it would take some work to avoid serious combing.

Paul S

10-25-2022

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Paul S
San Diego, California, USA
Posts 2,657
Joined on 10-12-2006

Post #:	239
Post ID:	26932
Reply to:	26929

New Age Physicist?

Jarek, don't worry about me spending too much time trying to figure out the Dannoys. For one thing, I've already spent several decades charting vintage and newer "special" drivers and sound. For another, I am already years into my own speaker project that more-or-less combines the "knowledge" I've accrued with a death defying leap of faith. And no matter what you say, everyone winds up trying one thing and then another, with some sort of "rationale" behind the moves; that's just how it is. It's not like one's intellect is simply put out to pasture. Rather, the awareness is honed and refined into a sort of intuition that seems to "work better" in terms of applicable aesthetics. If people are happy at 70 dB, I have no problem with it; just asking, matter-of-fact, since that's what Romy reported. Not to mention, it's hardly purely personal or random to try to replicate someone else's stated success by copying what are presumed to be the main components and features of what is assumed to be a or even the primary apparatus of the successful matrix.

Best regards,
Paul S

10-26-2022

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

Post #:	241
Post ID:	26934
Reply to:	26928

To answer your question

Paul S wrote:

It seems from following these threads that no one so far has been content to stay focused on recreating the accidental success of the original Dunnoy/Dannoy. Is this because no one can actually recreate the original, or is it because everyone has issues with these speakers that they'd prefer to improve on? For instance, don't we always say that one wants 20 dB headroom. Does this mean people are happy listening at 70 dB, or does it mean that something about the Danoy "offsets" the need for headroom? I still can't figure out how you can push the Red down to 50Hz with the original configuration and also get the headroom? While multiple Red drivers sans tweeters "sounds logical", it would take some work to avoid serious combing.

I have no idea what was the original accidental success, only those present there know. So I use my inner reference. The first sounds were not breathtaking, but the sound started to grow on me (i.e. I was missing it) and after changing the floor has become very very interesting and magnetizing. What I'm missing is some air, some breathing. There is sth like a veil I'd like to remove. I don't know yet if that is an inherently limited dynamical range of this simple configuration or other factors of my implementation:

1. The room: Not easy at all, pretty dead even when empty, complicated shape. Plus I've never had any speakers here (I moved few yrs ago and was concentrated on my Staxes) so only learning the room. After changing the floor the things have improved (=more alive). I start to research proper room treatment now. I also don't have much freedom in speaker location, which may not be the best in already difficult room.

2. Electronics: In lieu of a better one, I'm temporarily using Yamaha C1 pre which I got with B2. I suspect it is killing the sound. It was for sure killing bass in one of the channels due to a dirty pot. I plan to change it to 801A DIY. Also my B2 had dirty input pots and bypassing all that crap did help to open up the sound a bit.
3. The Staxes set the reference line very high, or perhaps better said, somewhere else. The direct and immediate connection to the musical material is hard to beat.
Other random comments:
1. When you look at the speaker response (e.g. my curves up the thread) a natural question arises if you can add some reinforcement below 50Hz? It does not feel much like one needs it when listening but a temptation grows to extend this magic of Dannoy bass even lower. That's why there is a lot of talking of adding drivers, active or passive, increasing the dias etc etc. In my personal context I was also hoping to get more of that "breathing" with a proper LF. Comments of the guys who had time to experiment with adding a LF are not very encouraging though - hard to extend the bass without spoiling the elegance of the sound.

2. IIRC, Bill measured 90+dB before distortion. Subjectively, they can play loud but "not into the face". In any case, in my room the sound of big orchestras is missing some scale and size. If this is inherent to this simple design, my room, my electronics, or a mix of all, I cannot say until I at least change the pre and play with the room.

Hope this answers a bit.

Cheers,
Jarek
STACORE

10-26-2022

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Edgar=
Posts 29
Joined on 02-13-2021

Post #:	243
Post ID:	26936
Reply to:	26928

The focus of recreating the accidental success

Hy Paul, I agree with your comment about the tone of the passive radiator if it runs to the mid range. This is the point of the SS8565. the combo of the crazy stiff cone and the special surround works phenomenally well to stay linear. It is even better when it is not driven! It does not add any tone, none at all and that is the point. It just rides the tannoy to bring the Fs way down without fu..... sh.. up. The bonus is it allows a tiny box. These tannoys, well maybe the 15 mostly, were designed to be loaded by huge rear horns which would pull the Fs way down. If you just load one with a few cubic feet box and listen is it not how the designers meant it to be, i believe. I'm not one to use passive radiators historically but had the drivers on hand to try Romys kinky config, So I did. The SS pulls the tannoy Fs way down and you get a really fun bottom octave in a few cubic ft. If you have a wife, Dunnoy will make her happy and you will have sex again.

Regarding blending a passive radiator do you mean up or down? I learnt how easy it is to blend it up by literally slapping it in a box with the tannoy. using the 8565 that is. Blending down well thats proving pretty difficult. It doesnt have to be a tannoy btw. try loading any good vintage wide band driver with the SS8565 in a tiny box. And i suppose it doesn't have to be the SS865 but i dont know of other woofers that offer the phenominal stiffness of the cone and the transparency of that suspension. It is a pretty unique driver. i would be keen to learn of a more economical solution because buying them from australia to just run passively is unfair expensive.

I never though of the difference in the smaller tannoys to the bigger as a differenece in jump from the cone fundamentals. I like that distinction. I only know the 10 and the 15 and they sure do sound different

Its not hard to recreate the magic with this set up. If you really want to critique the assertion that the combo of the tannoy and the scanspeak is worthy or not, do this -
1. organise yorself a vintage tannoy. not new HPD crap but proper alnico accordian surround vintage tannoy. red obviously is better but gold will do in my opinion if you want to see Dunnoys hot legs. (It is the coherence in the xover region of the vintage tannoys creating very wide coherent bandwidthe, combined with the speed and softness of the alnico motor and the sound of the cone and voice coil that excels IMO. Not many drivers or combination of drivers get all that right so readily. Vintage tannoy makes things easy in that it handles 8 octaves for you in a very linear and coherent fashion. linear in not just frequency but dynamically. The SS8565 give you another octave on the bottom for free)
2. Listen to your tannoy and make sure it is not injured. self explanatory really. Get another one if it is not perfecto
3. Organise yourself a SS8565 and marry it to your not injured vintage not HPD or any other new crap tannoy, in a way smaller than what your rational mind tells you box.
4. listen and fix your box if it is crap.
5. organise yourself reverb injection and forget all your room woes (and most of your other audio woes too for that matter)
6. take the day off

If you deviate from the above I cant guarantee you will meet Dunnoy...

BTW Paul, I dont think anyone disagrees about the headroom. In fact i think the focus might be not only how to recreate the magic but also get more headroom no?

10-26-2022

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Paul S
San Diego, California, USA
Posts 2,657
Joined on 10-12-2006

Post #:	244
Post ID:	26937
Reply to:	26936

The Good

Jarek, my experience affirms that many “listening rooms” are overdamped, and you can always put a rug or rugs on the wooden flooring where you want it/them. And I have been able to get good sound in weird rooms. Basically, regarding rooms, “too big” is a far bigger problem than “too small”. I do get the attraction of headphones, and the Stax, in particular, and I do understand “limited capacity” speakers, and that people have to be mindful of their living arrangements. What I don’t understand is that no one except Romy has mentioned (and bitched about) the (necessarily) limited acoustic power. What are you listening to?>>

> >

Edgar, I will not be trying the Dunnoys, just, as a longtime devote’ of vintage drivers, trying to wrap my head around the phenomenon, to try to figure out if, and if so, how, anyone managed to get “serious” acoustic power for Big Music down to 50 Hz from a single, FR Tannoy Red. I do understand that the “passive” Scanspeak might lower the Tannoy’s Fs, but how does that basically parasitic load increase the acoustic power of the Tannoy? It literally makes no sense. And 90 dB peaks means 70 dB steady, if to have 20 dB headroom, right? I like all kinds of vintage drivers and speakers for this and that reasons; but, apart from a few of the old “Pro” systems, those old speakers were a ways from bringing across orchestral music, and less and less so, over time, for me. I had some success getting acceptable power from vintage drivers by using multi-driver “stacks” that limited the drivers to comfortable bandwidths (around 2 1/2 octaves...). Still, I was plagued with combing, lobing, and other “phase issues” that I was not willing to spend yet more time (and money…) figuring out.>>

> >

>
>

> Best regards,>

> Paul S>

10-26-2022

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

Post #:	245
Post ID:	26938
Reply to:	26937

More answers and questions

@Edgar - No, I do not use reverb injections. What do you mean by "blending up and down"? What xovers do you use? I have the UK made ones as they worked best for me (the settings are described up in the thread).
@Paul - Not to praise my own arse, but top Staxes + top amp + top source is a trip to another dimension. I've spent about 10yrs polishing my Stax setup and with the right material it sends me on a long, deep trip. Well, as for the limited power, I did mention from the very beginning that big orchestras do not sound convincing in my Dannoy setup, missing the scale, the slam and the air. If this is the result of the limited power as the common sense suggests or sth in my setup (crappy pre) ot both, I'm yet to find out. I listen to a whole spectrum of classics, from medieval to contemporary, with a soft spot on baroque. My ears are about 2.4m from the Dannoys. And so far baroque consorts have been the most beautifully presented by Dannoys. Also a small scale (about 5-6 instruments) contemporary that I listened FM broadcasted life from a venue I know well was very good (just that particular music not my cup).

Cheers,
Jarek
STACORE

10-26-2022

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Edgar=
Posts 29
Joined on 02-13-2021

Post #:	246
Post ID:	26939
Reply to:	26938

Answers

@N-set I was replying to pauls comment about giving up on blending passive radiators and trying to say I was surprised how effortless the 8565 integrates upwards into the tannoy but integrating down into another channel there is no hope. I think the later part of that comment is universal to passive radiators however the former part may not be. Re crossovers i just use the generic old ones as is. seem fine enough.
If you are confidant your tannoys are working OK then i boldly request please stop everything else you do in audio right now and organise yourself reverb injection. the extra pressure from the reverb channels adds non directional bass energy to your room and the decay of that energy is adjustable with the settings on the reverb unit. I cannot overstate the difference it makes. it will be the cheapest and best upgrade in audio you ever made. I think it works particularly well with Dunnoy given the short comings. If you use big speakers for the reverb injection they can load the room with a lot of pressure. stick to only 2 rear channels of course. If you do, you will not have any integration woes only joys. If you have complaints about your room they will disappear for you. I know this is all very bold declaration but from one dunnoy user to another, do your self the favour. particularly for your funny shaped room.

10-27-2022

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Romy the Cat

Boston, MA
Posts 10,156
Joined on 05-28-2004

Post #:	247
Post ID:	26940
Reply to:	26939

Ehh....

Edgar= wrote:
but integrating down into another channel there is no hope.

Good, so much appreciate you to saying it as I kind of feel like I'm a freaking loser there's this configuration quite defeated me. my self-esteem is saved and my ego is erected again. With all seriousness it is indeed very challenging and I hope somebody, or perhaps me will be able to crack it in the future.

Edgar= wrote:
i boldly request please stop everything else you do in audio right now and organise yourself reverb injection.

This is absolutely ridiculing statement, clearly indigotic point of view but I fully support it. I wish the reverb injection would be more popular in very much high end audio and in my view it gives more listening benefits then to update you speakers or amplifiers to something that cost 100 time mores then what you have.

Edgar= wrote:
If you are confidant your tannoys are working OK then i boldly request please stop everything else

Here I very much disagree. Tannoys in Dannoy configuration driven by VFET is incredibly interesting configuration but it is not a complete configuration, at least if you're not listening in exceptionally small listening room. each single Hertz that tannoy going down it picks up some compression and it became unpleasant. I am not trying to pontificate from a position of high wisdom as I did not resolve this puzzle but the Dannoy + VFET is for me, for the time being, is dead end solution. I also highly recommend try VFET with Dannoy. I did not have a lot of amplification but after I assemble my Dannoy I was trying to drive it with my Milquades amplifier, and it was very bad. Are personally feel they to drive Dannoy with a low power amplifier with high output impedance is very dangerous as at the bottom Dannoy represents is very complex load which make most of the low power amplifiers to clip and while they doing it they create very nasty high frequency distortions which can even damage twitters. I tried that, and I was trying by-amping but Milquades delivered very bad results in term of dynamics, base quality and certain sense of rhythm which was completely killed.

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

10-27-2022

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Edgar=
Posts 29
Joined on 02-13-2021

Post #:	249
Post ID:	26942
Reply to:	26940

It is complex

Yes a few ridiculous requests and statements there indeed. Full ridiculousness intended.
I know Dunnoy needs a lot of power and low impedance amp. My aims are not the same as yours here as I'm not concerned to have a SS amp. I am concerned with having things be generally smaller though. I will organise to listen to a VFET so I have a reference for it.
Regarding integrating bass, the problem I think is how rapidly the active radiator decouples from the passive one below the passive radiators Fs. Being such a sharp lower knee makes it hard.
If you were to high pass successfully I guess it would need to be 3rd or 4th order right below the system Fs. The free air Fs of the 8565 is 20hz but obviously higher in a small box. There is more to it however. I think the challenge with high passing is sure, now there is no program material going to the speaker below Fs, but the passive radiator still has it phase shift. And probably worse now because the active radiator is not playing lower, it is not countering the phase shift. Maybe a solution might be driving the passive radiator lowpassed but out of phase, to help flatten that lower knee. What I mean is say 100w low impedance amp with 20hz-40hz, 4th order lowpass filter driving the passive radiator (which yes is technically now no longer passive) out of phase. Might be interesting to try. Might be able to flatten that knee completly out having no phase shift of the passive radiator at all. That would then improve things impedance wise for the Tannoy and amp combo as well.

@N-set, Yeah my thinking is if you are going to add more channels then have them coupled to the passive driver. either their own passive radiator or share the one with the tannoy. If it is a sub scenario then probably its own passive radiator would be better as a guess.
My comments re injection are just my comments, of course you will do what is right for you.

10-28-2022

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

Post #:	250
Post ID:	26943
Reply to:	26942

LF cont'ed

Looks like the phase response is quite complicated, with two phase flips between the knee and the Fs notch, but the PR phase eventually comes back to be in phase below the Fs:
"I am sure we have all heard that a passive radiator is like a vented speaker. This is true in the region of the box tuning frequency. The passive radiator acts like a mass hanging on the spring and can be used to tune the box compliance to the desired resonance frequency in much the same way as a port does.In both cases, port or passive radiator, the resonance creates a very high internal pressure in the box at this frequency. This pressure, if there were zero losses, would force cone travel to come to zero at this frequency as all output would come from the port or passive radiator at this frequency. However, there are some losses, so in reality we end up with a notch in the woofer's response at the tuned frequency (Fb) and most of the output does still come from the port / PR.Now, as we move below Fb the passive radiator begins to act very differently than a port. Here's why - You still have that image of a weight hanging a spring? Well, a passive radiator is a much more complex mechanical system than a simple port. It has its own moving suspension and it has its own resonance frequency ( which we will call Fsp). So in your image of the weight hanging from the spring, you need to attach another spring to the weight and add an additional weight hanging on it. So, now you have a weight on a spring hanging from a weight on a spring. Got that, right? In a vented system the port output and the cone output are in phase with each at the tuning frequency. Below that both are rolling off at 12 dB/oct. But, the port is moving out of phase with the cone as the frequency decreases. This is what causes vented systems to roll-off at 24 dB/oct. The same thing occurs with a passive radiator until we reach the frequency of Fsp. At this point (Fsp) the passive radiator output is out of phase with the output of the woofer cone and a notch in the summed response occurs. At this point the PR's phase "wraps" or flips, and below Fsp the PR's phase moves back in phase with the cone. This means that at very low frequencies the summed response, unlike the vented system, rolls-off at only 12 dB/oct, just like a sealed system. In fact, it is a sealed system below Fsp. This means we have the added benefit of the box no longer unloading at low frequencies like a vented box does. Excursions of the woofer cone are much better controlled at very low frequencies. With the Passive Radiator, you get the benefit of a vented box at the tuning frequency and the benefit of a sealed box at lower frequencies. You may have never heard this before, which is what makes this a smarter place to hang out."
https://diy.midwestaudio.club/discussion/909/ported-vs-passive-radiator-designs-thoughts

I understand this violent phase change happening in a short freq interval is one suspect why "glueing" bass/reinforcement channels is so problematic and they sound disconnected?

Ed, would love to learn the details of your reverb application. It is in my plans (after sorting the electronics and a basic room treatment).

Cheers,
Jarek
STACORE

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»	New	Macondo's Axioms: Horn-loaded acoustic systems..	A link to another thread....	Horn-Loaded Speakers Forum	120	680438	07-29-2007
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