hi Joe, you are absolutely correct. The WG and coherer is narrowing dispersion at 1-5kHz and widening above around 8kHz. this directly changes the on axis response : narrowing means gain and widening reduces the on axis response. the 10k sensitivity simply depends on the choice of wave guide and coherer. The Spk16 demo has the insane beam width of +/- 70 degrees to 20kHz and this of course causes a drooping sensitivity above 10k. The tweeter yes a huge 80mm neo ring magnet and has an underhung coil with 1mm linear one way stroke.
+/- 70 degrees is huge coverage(140 degrees total). That is like wall to wall coverage. Given the chance I will give it a try
My ears are trained to listen to maybe 90 X 50 with the speakers toed in to cross in front of the sweet spot. You know with more direct sound and less wall, floor and ceiling reflection.
For now I will keep PT 90 X 50 Wave Guides with D2 Compression Drivers perched on my big speakers and ScanSPEAK 2608 tweeters with Joes' waveguides on my mini bench speakers.
My ears are trained to listen to maybe 90 X 50 with the speakers toed in to cross in front of the sweet spot. You know with more direct sound and less wall, floor and ceiling reflection.
For now I will keep PT 90 X 50 Wave Guides with D2 Compression Drivers perched on my big speakers and ScanSPEAK 2608 tweeters with Joes' waveguides on my mini bench speakers.
Any updates about the upcoming "NAC" version? I've been anticipating it for quite sometime now, since I've been eyeing the SB ceramic drivers for my next build. I'm a fan of how the Revel PerformaBe series look but there are not many afforable DIY designs that use all white drivers. Only Javad's and the late Bagby's Ceramicos and the late Rick Craig's Ceramicas came to mind, but those designs lack testimonials unlike the Elsinores. I really hope the NAC version would turn out great as I know the SB almunium drivers are totally interchangable with the ceramics (at least the 6 inch woofers), since SB themselves have both of them utilized in their own Bromo speaker kits using the same crossover networks!
https://sbacoustics.com/product/bromo/
In fact I've heard to both versions of Bromo a few years ago and really liked how clear and detailed the ceramic (-coated aluminium) version sounded compared to the aluminium version and have been longing to use the drivers in my future builds.
https://sbacoustics.com/product/bromo/
In fact I've heard to both versions of Bromo a few years ago and really liked how clear and detailed the ceramic (-coated aluminium) version sounded compared to the aluminium version and have been longing to use the drivers in my future builds.
Sorry for the belated reply. I can't wait till you publish all the details, it sounds like soon? It sounds (no pun intended) very interesting/impressive. I can't wait till you publish all the details, maybe soon?
Yes, I think we all know how it works and that it is the boundary effect that shapes the result. With my own waveguide I aimed almost singularly to get the maximum lift I could get down to around 3KHz with 45-45° and not a large flare, trial and error in 2012. It is reasonably effective in a crude sort of way. Below is a calibrated dB-SPL measurement, Red On Axis, Green 15° (modeled for and the smoothest) Off Axis and Blue 30° Off Axis. But take a close look at the Green as this is the result I was aiming at.
Easier when it is shown on its own below. The target sensitivity was circa 92dB/2.83V and 15° off axis listening:
Back in 2012, it got me close to what I was aiming at. Not saying that there is better out there now, but it works. I also aimed at the smallest value series capacitor I can get away with. For reasons to complex to explain here, I wanted as much 'impedance' between the tweeter as possible, especially near the crossover. For example, one active speaker with the amplifier connected directly to the tweeter, it had a glassy quality. Adding a series resistor and increasing the gain in the amp to compensate, that suppressed that glassiness. I believe I know the reasons and working on a measurement that I hope will explain why.
I feel the need to comment on something: I see some use the WG to lower the crossover frequency and I understand the reasons for that. The other option is to resist the temptation not to lower the crossover but to lower the distortion. I am in the latter camp of lower distortion. You might like to know this, but before the pandemic I went to Herning and spent three hours talking to Ulrik Schmidt, the designer of SB Acoustics (Danesian Audio) drivers and we had a wide ranging discussion. I thank him for his indulgence. I showed him the WG I use in the Elsinores. He said that he was working on a WG tweeter and that ended up being the Sartori TW29BNWG which you no doubt has seen been paired with your Purifi drivers, like the March Audio speakers (pic below). The 8 Ohm version could definitely be used in the Elsinores as the sensitivity is quite high even in the 8 Ohm version. If you could match that as well, then yes, it could be used in the Elsinores ULD "Mk2". But the S-S D2608 tweeter being used now also has an interesting history as the design was influenced by a Russell Storey down here in Ozstralia. With WG the distortion is very low indeed.
Tweeter: SB Sartori TW29BNWG
Anyway, coming back to that discussion with Ulrik, since we were discussing tweeters I brought up the fact that so many tweeters, even many highly regarded, are quite unacceptable when it comes to producing distortion at the low end of the passband. He then said something that nearly bowled me over, that his experience over time was that 3KHz is the most natural crossover frequency when combining drivers. This came from him without any prompting from me. I had come to the same conclusion and pretty much all my designs, with very few exceptions, I have ended up with circa 3KHz crossovers as the natural fit, this indeed also applies to the Elsinores. If you know him or ever see him, maybe bring that up with him. Carsten Tinggaard would know him for sure.
You say that the SPK16 will be using an underhung voice coil. I know from experience that will impact sensitivity, so yes, you would need a very powerful magnet, as I see it.
So what is the time frame for Spk16? Or at least a full set of details?
Cheers, Joe
Yes, in the measurement phase, and soon will be having the complete lot done. The acoustic measurements are done last and outdoors, the so-called farfield measurements. I don't use one metre measurements, I do them at 2 metres. This means it has to be done outdoors and not too cold, no rain around and almost no wind.
But this is definitely happening, but these things happen in there own time and not a rush job. It will be a quicker than developing the ULD version. I am very keen to see what we end up with. Never thought I would do a 'hard cone' version of the Elsinores.
Hello all,
I am in the final stages of my build. Due to the fact that the crossover will be implemented externally, the floor inside the box remains free. I wonder if to reduce standing waves between the floor and the top in the box, it might be advantageous to glue small wooden triangular building blocks on the floor:
What do you guys think? Would this interfere with Joe's tuning of the box?
Thank you very much for your opinion and greetings, Henning
I am in the final stages of my build. Due to the fact that the crossover will be implemented externally, the floor inside the box remains free. I wonder if to reduce standing waves between the floor and the top in the box, it might be advantageous to glue small wooden triangular building blocks on the floor:
What do you guys think? Would this interfere with Joe's tuning of the box?
Thank you very much for your opinion and greetings, Henning
"NBAC" Update:
The weather last Sunday was too windy to get the far-field measurements done. I use 2 metres rather than the usual 1 metres. That means it can only be done outdoors and on a good day. As I need help the next opportunity is this coming Sunday. All the near-field measurements are done, as well as the electrical in-box Z plots. So we are well on the way.
The weather forecast this coming Sunday looks really goo.
ISSUE:
Take a look below, a quick test of the Ceramic/Aluminium Tweeter, can you spot something?
No phase plate!
I am having an issue with the Ceramic/Aluminum Tweeter. I am getting a suck-out around 9KHz.
The picture above shows the Tweeter without the phase plate. I always wondered if there was going to be an interference between the phase plate and the Waveguide, and if so what frequency. I knew it would be fairly high up and sure enough there was a major suckout at 9KHz.
I then removed it with a pair of sharp cutters and got the following "on" and "off" axis family of responses below and no suckout. It looks very consistent.
The waveguide "gain" looks good too, between 10KHz and down to 3KHz..
This was a quick measurement, but the results confirmed that waveguide gain we are looking for. Interesting, the above 20KHz peak that you get with hard domes is largely not there, just a bump. It was more prominent with the phase plate as this RTA measurement confirms:
You can see that the suckout wrecks the waveguide gain and does not eliminate the circa 25KHz peak.
Any other issues?
Well, the dome is not as well protected, but the insert of the waveguide does give it some. They are not hard to swap out the VC & Dome assembly, are they available as spares from SB Acoustics. I haven't checked. But beware of young children, hard dome don't have the spring back of soft domes.
The nex main issue is the Tweeter's lower sensitivity and being 4 Ohm. The lower sensitivity of the NBAC driver will hopefully help out here. But I suspect that the impedance above 5KHz might drop as low as 4 Ohm, but we shall see.
By this time next week I should be able to publish results about where the modeling end up.
The weather last Sunday was too windy to get the far-field measurements done. I use 2 metres rather than the usual 1 metres. That means it can only be done outdoors and on a good day. As I need help the next opportunity is this coming Sunday. All the near-field measurements are done, as well as the electrical in-box Z plots. So we are well on the way.
The weather forecast this coming Sunday looks really goo.
ISSUE:
Take a look below, a quick test of the Ceramic/Aluminium Tweeter, can you spot something?
No phase plate!
I am having an issue with the Ceramic/Aluminum Tweeter. I am getting a suck-out around 9KHz.
The picture above shows the Tweeter without the phase plate. I always wondered if there was going to be an interference between the phase plate and the Waveguide, and if so what frequency. I knew it would be fairly high up and sure enough there was a major suckout at 9KHz.
I then removed it with a pair of sharp cutters and got the following "on" and "off" axis family of responses below and no suckout. It looks very consistent.
The waveguide "gain" looks good too, between 10KHz and down to 3KHz..
This was a quick measurement, but the results confirmed that waveguide gain we are looking for. Interesting, the above 20KHz peak that you get with hard domes is largely not there, just a bump. It was more prominent with the phase plate as this RTA measurement confirms:
You can see that the suckout wrecks the waveguide gain and does not eliminate the circa 25KHz peak.
Any other issues?
Well, the dome is not as well protected, but the insert of the waveguide does give it some. They are not hard to swap out the VC & Dome assembly, are they available as spares from SB Acoustics. I haven't checked. But beware of young children, hard dome don't have the spring back of soft domes.
The nex main issue is the Tweeter's lower sensitivity and being 4 Ohm. The lower sensitivity of the NBAC driver will hopefully help out here. But I suspect that the impedance above 5KHz might drop as low as 4 Ohm, but we shall see.
By this time next week I should be able to publish results about where the modeling end up.
I honestly don't think it will do that much. What happens if you reduce the volume of the box? The box tuning frequency will go up, slightly and will increase output above the frequency and lower it below it, slightly. Will it break up any vertical internal resonances? This usually shows up in the impedance plot and they are not there. The drivers vertical line, spread out, plus the internal damping, it can be seen as already sorted. So I would not use it.
By the way, maybe it is time to show some pics of my build. It was a great experience thus far, being my first contact with woodwork ever. A dear colleague of mine and me we both helped each other and we both build a pair for each of us.
The foot plate for installing the Gaia feet later was done by a guy here in Germany who is specialised in milling custom speaker stands (for quite a reasonable price) and the result is just marvelous. Can‘t wait to let the Elsinores sing!
The foot plate for installing the Gaia feet later was done by a guy here in Germany who is specialised in milling custom speaker stands (for quite a reasonable price) and the result is just marvelous. Can‘t wait to let the Elsinores sing!
HenSch:
Those are very handsome cabinets -- nice work! You're going to love the final product.
Regards.
Those are very handsome cabinets -- nice work! You're going to love the final product.
Regards.
HenSch,
I would echo the sentiments expressed by SRMcGee and WeBuild4Life - the cabinets look really nice - kudos to you and your colleague! 🙂
I would echo the sentiments expressed by SRMcGee and WeBuild4Life - the cabinets look really nice - kudos to you and your colleague! 🙂
There will be minimal effect for waves that can see these triangles as the distance and direction tend to remain the same as for the regular box.
Yep.
Lovely!
Any idea of the date completion? Yes, the Gaia feet will make a difference, and no, I am not in cahoots with them.
Many thanks to all of you for your positive feedback!
You are absolutely right, I lost the physics for a moment.
I have given the building blocks back to my son, seems like they are of more use in his hands. 🙂
@Joe Rasmussen: Should have finished them around mid of July.
You are absolutely right, I lost the physics for a moment.
I have given the building blocks back to my son, seems like they are of more use in his hands. 🙂
@Joe Rasmussen: Should have finished them around mid of July.
Sure, contact information can be found here: https://www.instagram.com/hifibassti/?hl=de or www.facebook.com/BasTiCNC
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