Upcoming Tom Danley Hifi speakers

[Jim Matthews]

So far as what these sound like, i am unavoidably biased but I think Erin is going to come out some time in the next couple weeks and have a listen so he may have some impression
Hope that helps
Tom Danley

Will the home office accept excess children or unused K'Nex sets/Ukuleles/LaCrosse gear as partial trade?

 

[richard12511]

Can't wait. Here on ASR we live and breathe for the next sighted listening report.

My first exposure to the SH50 was actually under blind conditions , which is partly why I'm so interested in it(and this speaker). Best imaging I've ever heard, to this day. I had no idea I was listening to a super directional point source speaker , but looking back, it makes sense.

Before I knew about the validity of measurements, blind test results were my go to for choosing speakers. A carry over from my quest to find my favorite beer.

 

[Newman]

More likely the narrow beam than point source IMO.

 

[AudioJester]

Wasn't there some trouble with Red Spade over potentially infringing on Geddes' intellectual property? I have been following it for a long time on DIYAudio and I think it's very promising indeed

Didnt know about this or the history of the synergy horn. Just looked and the speakers are still on the red spade website.
Perhaps Mr Danley can comment?
In any case I really want to hear some Danley synergy horns now.

 

[pozz]

@Tom Danley Any hint on pricing?

 

[Tom Danley]

That is a good point. What is your take on diffraction in your speakers for home use. The moulded horns look like they would perform better than the SH50 as far as diffraction goes.

Diffraction..
I would say the place to start is the baffle step frequency.
So lets say you had a big flat baffle with a tiny acoustic source at the center.
You find that at up high the sound radiates in a hemisphere, 180 degrees (meaning the -6dB points in the lobe)

BUT at some frequency, the radiation angle increases and eventually wraps around and radiates 360 degrees.


So starting high up, the baffle is large enough to confine the radiation angle to 180 degrees and HOW the sound can radiate past the edge of that baffle and not wrap around is exactly the same as how a horn can have a fixed radiation angle and the wave continue on it's way.


How is by forming a smooth curved wavefront that gradually expands exponentially until the geometry of the pressure distribution allows it to proceed free of the physical boundary.


All is well as long as the boundary is large and flat. Rather, as the wavefront expands and before it is large enough to radiate on it's on, a discontinuity in area or obstacle and several other things can cause a radiation from that point. That new and slightly delayed radiation causes fine structure comb filtering which can directly conflict with ones pina and HRTF's subjectively harming the stereo image and producing clues your ears can triangulate on as "sources in that location".


In other words diffraction is just one thing that can be especially harmful and when it's within the first 8 or 10 inches from the source, seems like that is most important NOT to have re-radiation.

Now the reflected sound off the room side walls is another issue next.


A horn particularly a conical types are or can literally be a fractional space condition, for a horn, that point where it stops confining the angle to X is 10^6 / horn angle / horn dimension inches. Each octave below that, the angle doubles.
I agree about the SM-60 horn horn shape, there are things you cant do with Baltic Birch haha.

The polar plots for the new speaker will be essentially the same the SM-60f (a little different down low) if you want to look the the CLF data, 3d polars etc


https://www.danleysoundlabs.com/support/clf-files/
Best
Tom

 

[richard12511]

More likely the narrow beam than point source IMO.

I think both contribute, but the narrow beam does contribute much more(imo), I agree. For example, the image of my JTR 210RT is a bit more vertically smeared than the image of the 212RT, due to it not being symmetrical around the horn. Both have the same 60x60 pattern and FR.

 

[fluid]

How is by forming a smooth curved wavefront that gradually expands exponentially until the geometry of the pressure distribution allows it to proceed free of the physical boundary.
...

In other words diffraction is just one thing that can be especially harmful and when it's within the first 8 or 10 inches from the source, seems like that is most important NOT to have re-radiation.

Perhaps my question was too vague, it is the diffraction from the horn taps which occur early on that I was wondering about. There has been an amount of interest in Multiple Entry Horns being built using horns with less diffraction than a conical. The secondary flare does make quite a difference to the polar uniformity but the diffraction remains. Do you think that a conical is still the best horn to use?

When I ran some BEM simulations the taps really upset the low diffraction waveguides but would not be that much worse than the background diffraction from the conical when driven by a flat(ish) wavefront from most compression drivers.

 

[Tom Danley]

That is a good point. What is your take on diffraction in your speakers for home use. The moulded horns look like they would perform better than the SH50 as far as diffraction goes.

I would say the place to start is the baffle step frequency.
So lets say you had a big flat baffle with a tiny acoustic source at the center.
You find that at up high the sound radiates in a hemispherical pattern, 180 degrees (meaning the -6dB points in the lobe)

BUT at some frequency, the radiation angle increases and eventually wraps around the baffle and radiates 360 degrees.
So starting high up, the baffle is large enough to confine the radiation angle to 180 degrees and HOW the sound can radiate past the edge of that baffle and not wrap around is exactly the same as how a horn can have a fixed radiation angle and the wave continue on it's way at the angle defined by the horn walls.
How is by forming a smooth curved wavefront that gradually expands exponentially until the geometry of the pressure distribution allows it to proceed free of the physical boundary at the edges.

All is well as long as the boundary is large and flat. Rather, as the wavefront expands and before it is large enough to radiate on it's on, a discontinuity in cross section area or obstacle and several other things can cause a radiation from that point. That radiation often causes fine structure comb filtering which can directly conflict with ones pina and HRTF's subjectively harming the stereo image and producing clues your ears can triangulate on as "a source in that location" and competes with the image in the recording.

In other words diffraction is just one thing that can be especially harmful and when it's within the first 8 or 10 inches from the source, seems like that is most important NOT to have re-radiation. Now the reflected sound off the room side walls is another issue next.

A horn particularly a conical types are or can literally be a fractional space condition, for a horn, that point where it stops confining the angle to X is 10^6 / horn angle / horn dimension inches. Each octave below that, the radiation angle doubles.

I agree about the SM-60 horn horn shape, there are things you cant do with Balitc Birch haha. The polar plots for the new speaker will be essentially the same the SM-60f (a little differnt down low) if you want to look the the CLF data, 3d polars etc
https://www.danleysoundlabs.com/support/clf-files/
Best
Tom

 

[Tom Danley]

@Tom Danley You mean the notch at 2 kHz? 1/4 wl is 42mm. Are you saying the holes for the mids are 42mm from the closed end of the SH50?

Hi
Yes...But when you look at a horn, exponential conical etc, what one finds that unlike a simple duct, is the acoustic length is less than the physical length. The "small end" is "Stiffer" and so the resonant length is not the same as the length measured with a ruler.

 

[Tom Danley]

Perhaps my question was too vague, it is the diffraction from the horn taps which occur early on that I was wondering about. There has been an amount of interest in Multiple Entry Horns being built using horns with less diffraction than a conical. The secondary flare does make quite a difference to the polar uniformity but the diffraction remains. Do you think that a conical is still the best horn to use?

When I ran some BEM simulations the taps really upset the low diffraction waveguides but would not be that much worse than the background diffraction from the conical when driven by a flat(ish) wavefront from most compression drivers.

 

[richard12511]

I agree about the SM-60 horn horn shape, there are things you cant do with Baltic Birch haha.

Tom

What's the reason for using baltic birch? My JTR speakers are made of the same thing, so I'm curious.

 

[TimVG]

What's the reason for using baltic birch? My JTR speakers are made of the same thing, so I'm curious.

Sturdier than mdf so they can be made thinner. Weight becomes a factor with big speakers. That would be my guess.

 

[Tom Danley]

Hi



Umm the design was developed not by simulation but measurements of the conditions that design produced. What i can say is that by comparing measurements of the horns with and without ports, the size and locations were established. It turns out that the corners of the horn are in a low pressure or shadow zone at higher frequencies compared to mid wall locations.


Consider that within the horn, where the mid drivers tie in, at around 4 inches across, the hf driver has pattern control (radiation angle set by the 50 degree horn wall) around 5KHz and above.

Yes the second angle is desirable as Don Keele discovered but I have not seen that other horn shapes can be made simply and control pattern as low in frequency (some of our horns are very large) and the early sh-50 cabinets had a sharp kink at that transition edge (later changed to a radius). In it's polar plots, you can see some high frequency edge radiation off axis from that sharp bend it used to have.

As one is dealing with something like a transmission line with radiation resistance, I would suggest modeling a more complete system and build and measure the results.

I do use modeling for horns, I design a lot of horns at work, often a program called AKABAK (what i used to find the Tapped Horn design) but there are some fudge factors and other issues that must be compensated in order to get the predicted results to match the measured results. That i think is the strength of software modeling, is only as strong as it's ability to predict what you measure when built.

See what you see in the full spherical polar for the sm-60f, it should be very similar to the new speaker as it has the same horn body.


Fwiw, the exit wave shape from compression drivers can be quite different, the ones with a dome and phase plug can be from planar to curved while the ring radiation compression drivers tend to produce an expanding wavefront.

Consider that at 20KHz, ALL of the impedance transformation has taken place by the time the horn exit diameter is about 5mm and at the 1 inch exit, that is large enough acoustically to confine the radiation angle to around 90 degrees with no horn.

In order to radiate the wide bandwidth "windowed point source" from a conical horn, the radiation angle has to be controlled by the horn walls not the source size. Remember too that horn loading on a piston (it's gain over a direct radiator) STOPS about when K=1 while the pattern control loss F is Don Keele's thumb rule.
Best
Tom

 

[Tom Danley]

What's the reason for using baltic birch? My JTR speakers are made of the same thing, so I'm curious.

Both of you are right, it has to do with strength, it is very strong and "Expected" in quality sound gear.
We use it and dado joints for the same reasons, some of our Speakers are very powerful so some places it's 1 1/2 inch thick Baltic.
Personally, I like the way it looks so when i make prototypes, i often finish them with Spar polyurethane which produces a nice golden / amber shade
Best,
Tom

 

[KSTR]

@Tom Danley, FWIW, for the diffraction from the exit holes in the horn throat, looks like @René - Acculution.com would be capable to set up a complex COMSOL topology optimization to get the lowest possible diffraction while still working perfectly as the exits of the lowpass chambers. And the chambers sure could be optimized also...as well as the whole horn geometry, etc. A whole new world is opening up here, see for example this fascinating stuff: https://www.acculution.com/single-post/2020/02/04/031-comsol-conference-2019-cambridge-presentation

 

[Tom Danley]

Hi
Hey Thanks for the link!
I had seen some of the modal modeling as it applied to RF wave guides but seeing the acoustic cases is interesting.
It would be interesting to see behavior over some bandwidth, say 1 octave.

There was a time a few years ago, i would have loved to have had that ability.
At a trade show, i had an image in my head how to combine multiple hf drivers into one radiation. I was excited, told Mike my partner "i see a way to do this" and then it took 4 long months of drawing and fiddling and little else to get what i could send off to have made to test.

https://patents.google.com/patent/US20120328140A1/en

Wow, hard to believe it was 10 years ago but here is Mike with the first outdoor test of the cabinet that combiner is in. An impromptu outdoor demo at a trade show after this test produced our first two stadium system jobs.

And it's first live sound use in Europe commentary by mix engineer RE past years

Best
Tom

 

[Hifisound]

Hi @Tom Danley ,

And 60x60 was chosen for home speaker instead of 90x60 (which even the Danley cinema line also uses) for certain specific reasons ?

Thanks!

 

[kimmosto]

when you're expecting perfection, the smallest problem can trigger an inquisitive listening state, a bit like searching for a mosquito in your bedroom.

Maybe, but at least I haven't created any problem from this. Weak hammer is quite easy to perceive, but root cause is more difficult to know because needs controlled comparisons.

But group delay and decay aren't exactly the same thing, no (unless it is because of minimal phase behaviour)?

Sorry my bad. I thought that you were talking about (also) group delay. Group delay is easier to analyze and kinda more exact. Decay tries to combine time and frequency domains -> result depends on analysis parameters. More visual but possibly less exact fact.

Also, it would be strange for Genelec to make such a paper and completely disregard it in their actual products.

Paper is public because it's university case. Genelec has participated.
As a speaker designer/manufacturer I cannot comment or judge their decisions and products. My strategy is to avoid too long excess group delay due to crossover that I wouldn't have to add any phase EQ with FIR to achieve acceptable (imo) excess GD down to upper bass. Realistic target has been about 2 ms @ 100 Hz with 3/4-way and 0.5 ms @ 100 Hz with 2-way. There will be some differences in strength of hammer due to differences in compression of drivers and radiator concepts, but healthy delay at least makes possible to get decent force to transients with less dynamic drivers/radiator concepts.

 

[Tom Danley]

Hi @Tom Danley ,

And 60x60 was chosen for home speaker instead of 90x60 (which even the Danley cinema line also uses) for certain specific reasons ?

Thanks!

Hi

Assuming one wants to primarily hear "direct sound" that contains the stereo information at the listening position in front of the speakers, the 90 degree wide horn in a living room (unless placed in a corner) would usually project more energy to the side walls than is ideal.

That wide and wider patterns are usually used in large rooms some distance above and in front of the audience to cover a side swath of ears.

A thumb rule in a living room with our horns generally would be that you ideally want the pattern's horizontal edges to reach the side walls somewhere past the half way point between the speaker and listening position. This, because of directivity will produce a very low sound level from the side and rear reflections.


For example at 500Hz a small horn like the SM-60f is still more than -10dB down 90 degrees off axis and more than -20dB down at 5KHz at 90 degrees off axis.

The result is anywhere in front sounds the same (has the same spectrum) although the stereo phantom image is best at the center equidistant as per normal.
If the listening position is a couch, one can aim the right speaker at the left most seat and vis versa. This trick makes the SPL more constant between seats by somewhat compensating for the different distances and inverse square law and so usually makes the sweetest spot wider.

Tom