Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

[ryanbouma]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

I finally took a me day and worked on the crossovers and have them pretty well dialed in.
Crossovers at 750 and 2 kHz.

0-90 Horizontal 1 meter on axis with tweeter 5ms gating 1/48 octave smoothing

Great build Dave.

How are you getting directivity so low? And how are you doing these measurements with the woofer where it is? Are you splicing a GP with a far field or what?

Great stuff.

[davepellegrene]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

Looking good Dave. Still a big fan of this project, and an even bigger fan of the potential derivative work if that is still on the calendar. Do you think the TB75 could go lower with a steeper slope and still provide very clean high SPL? Just wondering if the 750 Hz was as low as you wanted to take it or just a point that matched up well with sims against the DeltaLite? I am tempted to fly out to MWAF if you end up going because I really want to hear these things. My big dreams are still holding out for a 12x8 AST2560, a 12x8 slightly squared up for the TB75, and then I am currently thinking a pair of Beyma BR60v2 for the bottom end. All digital active of course, so that is why I am curious as to how low the TB75 is willing to go in that waveguide before you get the artificial sound you were describing...and I wonder if moving to a slightly bigger 12x8 with the corners squared up a little bit would allow for a bit more down low or if it would essentially behave the exact same way.

I played the TB75 solo with the crossover at 650 Hz. As I raised the volume what I heard would be like cupping my hands over my ears like a funnel. Once I raised the crossover to 750 and rolled the driver off a little stepper I could then run the volume up and it sounded good. I'm not sure if it was the driver or the guide creating the sound. It wasn't distorted sounding so I'm assuming the guide was creating it. Horn honk? I'm not sure what that sounds like. It is possible that the larger 12x8 guide would go deeper. Maybe a trapezium with the AST2560 above. Or just a boring double square guide.
I do plan on bringing the AST into the mix at some point but I really need to work with it as a monopole first. I'm just not sure how it's going to react with the rear sealed.
Another tweeter I am impressed with for the money is the SS D2604. My initial measurement where really good in the 8" round guide.
https://picasaweb.google.com/1016322...akD2604833000#

Dave

[davepellegrene]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

Dave, the zero to ninety degree polar for this design looks exceptional!

[ATTACH=CONFIG]46004[/ATTACH]

It looks as straight as a bullet. I can see why the speaker would have a broad sweet spot. I hope that I get a chance to listen to them when I come to pick up my sub.

Nice work as always!

Steve

The way tracking down the paint to match you sub is going they will be done. :o

Dave

[davepellegrene]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

I don't know if I've said it on this thread yet, but that is pure badarseness.

Dave your measurements and data is clearly in the big big boy league with this speaker.

I was surprised by the polars but I clearly can hear a difference from anything I've built to date. I'll be interested to hear how they sound in another room.

Dave

[davepellegrene]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

Great build Dave.

How are you getting directivity so low? And how are you doing these measurements with the woofer where it is? Are you splicing a GP with a far field or what?

Great stuff.

This is the TB75 ran with just the XT25 in the same combo guide. The TB is holding the directivity by itself down to 400 Hz.


The measurements are taken exactly like all of my measurements are when I post them of my tweeters in guides. Gated at 5ms, 1 meter on axis with the tweeter. Which is good down to about 300 Hz. I have a stand that swivels with the off axis measurements marked on the stand at 10 degree increments. No splicing done.

Dave

[Greggo]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

I played the TB75 solo with the crossover at 650 Hz. As I raised the volume what I heard would be like cupping my hands over my ears like a funnel. Once I raised the crossover to 750 and rolled the driver off a little stepper I could then run the volume up and it sounded good. I'm not sure if it was the driver or the guide creating the sound. It wasn't distorted sounding so I'm assuming the guide was creating it. Horn honk? I'm not sure what that sounds like. It is possible that the larger 12x8 guide would go deeper. Maybe a trapezium with the AST2560 above. Or just a boring double square guide.
I do plan on bringing the AST into the mix at some point but I really need to work with it as a monopole first. I'm just not sure how it's going to react with the rear sealed.
Another tweeter I am impressed with for the money is the SS D2604. My initial measurement where really good in the 8" round guide.
https://picasaweb.google.com/1016322...akD2604833000#

Dave

Thanks for the extra comments... it makes sense that something interesting is going on here with the way that dome is loading up in your waveguide. You really shouldn't be holding much directivity below 1 kHz but your polars show otherwise, making this a bit of a magical combination IMHO. If you end up with two boring square guides with the TB and AC, I am all over it... I have been working up some designs with the double 12x8 and then of course just pulling my hair out on woofer choices. I am all over the place on that piece of the puzzle and I may end up having to buy a few choices and test them out myself, just too many options out there. Also, I am trying not to sell the DeltaLite's short either, both the 10 and the 12 seem to have a few fans out there and since I have decided that subs are going to be a "must have" at some point anyways, I am just focused on finding the best 10 inch midbass that pairs well with the TB 75 and still gets down to at least 60 Hz so I can go with a mono sub without any concerns. I am thinking about a few choices each from Beyma, Eminence, AE, AC, even the ScanSpeak classic.. like I said, I am just all over the place right now and no idea where I will land.

I am just about 100% locked on your waveguides however, probably both the mid dome and a tweeter guide, but I suppose there is a still a chance I could end up with an MTM around a new N26 tweeter version in one of your waveguides and dual AE TD10m just to keep things simple. Finally, just to complete my babbling here, any curiosity around the Transducer Labs 2 inch mid dome? Wish they would release more information regarding the status on that driver...

[TN Allen]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

I was surprised by the polars but I clearly can hear a difference from anything I've built to date. I'll be interested to hear how they sound in another room.

Dave

Does what you hear seem to be indicated in the test results? I suspect a more complex testing approach may be necessary to documenting the effect of double waveguides on what is actually heard, especially combined elongated guides. I am not certain, but I think, based upon listening to these, that different sounds are enhanced in subtle ways around the 90 degrees of each guide quadrant, especially by the larger, deeper elongated guides for midrange.

I think someone tested an elongated guide comparing the long axis vertical vs. the long axis horizontal, though I don't recall the results. I know a friend and I were surprised at the variation in one voice while listening up close to one of the first elongated guides I milled. While it was obviously the same voice, there were noticeable differences in that voice at different places along one quadrant of the circumference of the guide. Of course, we may have imagined the differences, but it would be interesting to test and document these if they do indeed exist.

Perhaps combining complex waveguide surfaces also enhances the subjective listening effects. From what you say of this new system, you've certainly entered into a new level of providing music enjoyment for yourself and your customers.

[davepellegrene]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

Thanks for the extra comments... it makes sense that something interesting is going on here with the way that dome is loading up in your waveguide. You really shouldn't be holding much directivity below 1 kHz but your polars show otherwise, making this a bit of a magical combination IMHO. If you end up with two boring square guides with the TB and AC, I am all over it... I have been working up some designs with the double 12x8 and then of course just pulling my hair out on woofer choices. I am all over the place on that piece of the puzzle and I may end up having to buy a few choices and test them out myself, just too many options out there. Also, I am trying not to sell the DeltaLite's short either, both the 10 and the 12 seem to have a few fans out there and since I have decided that subs are going to be a "must have" at some point anyways, I am just focused on finding the best 10 inch midbass that pairs well with the TB 75 and still gets down to at least 60 Hz so I can go with a mono sub without any concerns. I am thinking about a few choices each from Beyma, Eminence, AE, AC, even the ScanSpeak classic.. like I said, I am just all over the place right now and no idea where I will land.

I am just about 100% locked on your waveguides however, probably both the mid dome and a tweeter guide, but I suppose there is a still a chance I could end up with an MTM around a new N26 tweeter version in one of your waveguides and dual AE TD10m just to keep things simple. Finally, just to complete my babbling here, any curiosity around the Transducer Labs 2 inch mid dome? Wish they would release more information regarding the status on that driver...

I would think the 12" woofer has something to do with the directivity going this low.

This is my Black Box Speaker that won at the InDIYana event last year. It's a two way with a 6" woofer and the tweeter in a 165mm x 115mm guide. They are crossed at 2.1 kHz I believe.


This is another two way with an 8" concentric driver. Doesn't hold quite as low.


This is the 18Sounds 8" with the Audax tweeter in I believe a 7x5 guide.


These were all measured in the same set up as the combo guide.
So I don't really think there is anything special going on.

I'm using a single sub with the Deltalites and it does just fine in the room I'm set up in. The 12" woofer I think looks good with the size of the combo guide. A 10" may look a little small.



I didn't know Transducer Labs had a 2" dome.

A while back I tested the 2" Aura Whisper in a couple guides. An 8" round and in the 11x6. I was surprised it did so well being an inverted dome.
https://picasaweb.google.com/1016322.../2AuraWhisper#

Dave

[davepellegrene]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

Does what you hear seem to be indicated in the test results? I suspect a more complex testing approach may be necessary to documenting the effect of double waveguides on what is actually heard, especially combined elongated guides. I am not certain, but I think, based upon listening to these, that different sounds are enhanced in subtle ways around the 90 degrees of each guide quadrant, especially by the larger, deeper elongated guides for midrange.

I think someone tested an elongated guide comparing the long axis vertical vs. the long axis horizontal, though I don't recall the results. I know a friend and I were surprised at the variation in one voice while listening up close to one of the first elongated guides I milled. While it was obviously the same voice, there were noticeable differences in that voice at different places along one quadrant of the circumference of the guide. Of course, we may have imagined the differences, but it would be interesting to test and document these if they do indeed exist.

Perhaps combining complex waveguide surfaces also enhances the subjective listening effects. From what you say of this new system, you've certainly entered into a new level of providing music enjoyment for yourself and your customers.

No it doesn't show up in the measurements. It doesn't show in the distortion plots either. As I mentioned it doesn't sound like an over driven driver so I wouldn't expect it to show in the distortion. I can tell you it would be fatiguing. I hear a similar sound in the tweeter guides when crossed to low and played loud. This is also crossing above were third order distortion starts to climb. With the tweeters I usually end up raising the crossover point 400 Hz above what the polars would show as the cut off point. It's easy to hear when playing the driver alone.

I've never built a speaker using a round guide so I couldn't tell you if it is due to the elliptical shape.

I don't really see the advantage to push a driver low if the the driver your crossing to can come up to meet it without sounding bad or beaming. It should be able to play cleaner being the larger driver.

Dave

[Pete Schumacher]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

No it doesn't show up in the measurements. It doesn't show in the distortion plots either. As I mentioned it doesn't sound like an over driven driver so I wouldn't expect it to show in the distortion. I can tell you it would be fatiguing. I hear a similar sound in the tweeter guides when crossed to low and played loud. This is also crossing above were third order distortion starts to climb. With the tweeters I usually end up raising the crossover point 400 Hz above what the polars would show as the cut off point. It's easy to hear when playing the driver alone.

I've never built a speaker using a round guide so I couldn't tell you if it is due to the elliptical shape.

I don't really see the advantage to push a driver low if the the driver you're crossing to can come up to meet it without sounding bad or beaming. It should be able to play cleaner being the larger driver.

Dave

I would guess that the "horn sound" would show up in the time domain as excess decay. And this is another guess, but I would think it would be more prevalent in the elliptical guide due to the steeper walls on the short sides allowing standing waves to set up between the steeper edges.

This is just a hunch, but looking at the geometry with a very simple approximation, any guide with a wall that exceeds 45 degrees will begin to suffer from those cross sectional standing waves, where the wavefront off the dome has a chance to bounce back and forth off the walls before it leaves the mouth of the guide.

[buzzforb]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

I am glad to hear you two vocalize this. It makes me want to try the same tweeter on a round guide in order to do a direct comparison.

[davepellegrene]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

I would guess that the "horn sound" would show up in the time domain as excess decay. And this is another guess, but I would think it would be more prevalent in the elliptical guide due to the steeper walls on the short sides allowing standing waves to set up between the steeper edges.

This is just a hunch, but looking at the geometry with a very simple approximation, any guide with a wall that exceeds 45 degrees will begin to suffer from those cross sectional standing waves, where the wavefront off the dome has a chance to bounce back and forth off the walls before it leaves the mouth of the guide.

So you think this would show up in the impulse response? I would think the louder you play the sweep the longer it would take for it to decay so it would be hard to test unless comparing an elliptical to round. Still the round guide would be larger so it would still not be a fair comparison. Do you think it has to do with playing to low of a signal through the guide forcing a larger wave through it resulting in more reflections? Raising the volume would make it more audible. I do know the steep walls on a round guide has more reflections than a shallower guide. This is one of the reasons I moved toward shallower guides. Also an elliptical guide has less reflections on axis then a round guide. So as usual it's all trade offs shallower guide means more off axis signal steeper guide means more reflections. Elliptical guide is less on axis reflections and closer CTC. Round guide will play deeper on the same width baffle put with more on axis reflections and farther CTC spacing.

Dave

[Greggo]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

I think Pete's theory makes pretty good sense. I think we are all just curious to understand the variables here.... I do think the elliptical is the way to go and the right set of trade-offs, and the shallow form factor as well. Also, regarding how/when to move the crossover points up/down between any pair of drivers I can only say that speaking for myself I am always looking for the combination that gives each driver the most headroom to deal with dynamics without compromising the passband. I wonder if rear-mounting the woofer also helps with the midrange to low midrange directivity control as well?

I asked about moving the TB 75 a little lower only because I am finding a bunch of home hifi woofers that seem to have big dips around 600 Hz and leaves me wondering if they would sound best crossed right there or slightly below. Very amateurish thinking I know. Then again, I wonder about just going with an AE TD12 and getting it over with, no more second guessing about the woofer but a little more painful on the budget.

[Wolf]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

I didn't know Transducer Labs had a 2" dome.

Dave

It says it's a 72mm VC from the link on the website, and that it's a graphite dome, so it's likely closer to 3".
All the model designations hold this truth.
http://www.transducerlab.com/6501/128623.html

I'm interested in it when it comes out too!

Later,
Wolf

[ryanbouma]

Re: Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

Sorry to push the issue, but how wide is the WG on the mid. I don't see how it can physically hold directivity down to 400hz unless it's very very deep or something. 400hz is a very long wavelength. That thing should be omni by maybe 900hz if you're lucky. Then the woofer might hold directivity down to 600hz and totally wide open by about 300hz.