Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

[Pete Schumacher]

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.

Could be how Dave us using the turntable? Unless the drivers are sitting on the rotation axis, as the table turns, the drivers will all move away from the mic.

[davepellegrene]

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

I have my turntable set up so the drivers acoustical center is close to the pivot point of the turntable.
The baffle front I believe is an inch or so forward of center. Which would be close to driver acoustic center on most drivers. I'll be setting back up shortly for some measurements when I move the crossover for mid/ tweeter up. I'll see if I get the same measurements and also check the alignment closer.

I'll post a pic of the set up. I don't know of anything in the software that may change the results. I'm using omni mic.

Dave

[ryanbouma]

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

Could be how Dave us using the turntable? Unless the drivers are sitting on the rotation axis, as the table turns, the drivers will all move away from the mic.

I hadn't thought of that, good suggestion.

I have my turntable set up so the drivers acoustical center is close to the pivot point of the turntable.
The baffle front I believe is an inch or so forward of center. Which would be close to driver acoustic center on most drivers. I'll be setting back up shortly for some measurements when I move the crossover for mid/ tweeter up. I'll see if I get the same measurements and also check the alignment closer.

I'll post a pic of the set up. I don't know of anything in the software that may change the results. I'm using omni mic.

Dave

Hmm, probably not that then.

Just for information, here's Bill's directivity of the deltalite 2512.

http://www.diysoundgroup.com/forum/index.php?topic=9.0

He stops at 700hz because things go wide from there down.

WAIT!, is this an open baffle speaker? That could be it. I didn't follow the build process very closely.

[davepellegrene]

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

I hadn't thought of that, good suggestion.



Hmm, probably not that then.

Just for information, here's Bill's directivity of the deltalite 2512.

http://www.diysoundgroup.com/forum/index.php?topic=9.0

He stops at 700hz because things go wide from there down.

WAIT!, is this an open baffle speaker? That could be it. I didn't follow the build process very closely.

No, I'm sealed.
If you look at Bills frequency response graph, it goes down below 200 Hz, above his polar graph it looks the same as mine. Just not quite as flat on the bottom end from 0-30 degrees. So I would assume his polar would look similar down that low.

Dave

[ryanbouma]

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

Yes there is still some spreading below 700hz, but it's getting pretty wide compared to the 45d. And by 300hz it's wide open. As I mentioned, I'd expect the 2512 to hold a 45d pattern to 600hz (at best) and then widen out down to 300hz and totally omni below that.

It's hard to read, but it looks like that is what's happening in your FR plots. But the polar looks confusing like it's holding directivity down to 300 and even lower. I'm betting the data is good, I just wonder how these polars are coming out like this.

[ryanbouma]

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

Ya know, looking at it again, I think it's cause the mid waveguide is actually 60d. And also, the polars aren't normalized. I'm used to 0db normalized and then just look down the -6db line to see where directivity is. So I think it's just me not use to looking at them this way. The polar for the whole speaker does still seem odd down in the 300 to 500hz range, but I'm guess the 5ms gate isn't holding back all the reflection contamination.

[Big Stogie]

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

where does that waveguide come from?

[davepellegrene]

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

where does that waveguide come from?

I fabricate them. It's not on my website yet but will be soon. You can get there from my link in my signature. I have quite a few guides available but not listed yet. The Picasa site in my signature shows all the measurements of all the tweeter/ guide combinations I have. If it's on the Picasa site I can fabricate it. I need to take the time and get them all up.

Dave

[TN Allen]

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

... 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

Fascinating discussion, long overdue!

Round, intersected guides can also diminish center to center distance, and probably help to blend sound from individual drivers. These are complex shapes to produce. I think Dave has potentially shifted, in a positive direction, DIY speaker design and building. My guess is that when others hear music through his new system, they will realize, as he has indicated, that his new system is better than what he/they have previously achieved. I hope I have not mis-characterized his estimation of his new system.

[davepellegrene]

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

Fascinating discussion, long overdue!

Round, intersected guides can also diminish center to center distance, and probably help to blend sound from individual drivers. These are complex shapes to produce. I think Dave has potentially shifted, in a positive direction, DIY speaker design and building. My guess is that when others hear music through his new system, they will realize, as he has indicated, that his new system is better than what he/they have previously achieved. I hope I have not mis-characterized his estimation of his new system.

My first attempt of the combo guide was intersecting elliptical guides. Were they came together left a sharp edge. I got quite a bit of diffraction off that edge. Mostly in the tweeter response. It diminished as I went off axis but I figured why start with a flawed design. Splitting the guides so there was a smooth transition between the guides took care of it. That intersected guide also lost a couple dbs of boost compared to the separate guides. As the combo guide is now, with the mid being 11x6 and the tweeter guide 8x5, the CTC is only 3/8" wider then if both drivers were mounted on a flat baffle.

As far as these speakers sound I really like them. Once I get crossovers built I will take them up into my living room which is quite large,reflective and will suck the bass out of any speaker. The little dipoles I built with the AST2560 with my 165mm x 115mm guide did really well in that room so we'll see.

Dave

[TN Allen]

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

My first attempt of the combo guide was intersecting elliptical guides. Were they came together left a sharp edge. I got quite a bit of diffraction off that edge. Mostly in the tweeter response. It diminished as I went off axis but I figured why start with a flawed design. Splitting the guides so there was a smooth transition between the guides took care of it. That intersected guide also lost a couple dbs of boost compared to the separate guides. As the combo guide is now, with the mid being 11x6 and the tweeter guide 8x5, the CTC is only 3/8" wider then if both drivers were mounted on a flat baffle.

As far as these speakers sound I really like them. Once I get crossovers built I will take them up into my living room which is quite large,reflective and will suck the bass out of any speaker. The little dipoles I built with the AST2560 with my 165mm x 115mm guide did really well in that room so we'll see.

Dave

Probably in the long run listening will be the best way to evaluate the speakers. Given some time, living with them may be a good way to sort out what the test results really mean, and what is relevant. It's great that you have a balanced approach that includes testing and listening.

Another important potential for waveguide design is that these might be designed to accommodate individual hearing strengths and weaknesses, as well as taste. What is frequently thought to be desirable test results might be adjusted through judicious use of the guides and crossovers to enhance the listening experience of an individual. Many people, especially those who have compromised hearing might welcome an opportunity to have a system designed that would provide them with a more natural listening experience. For myself, waveguides have eliminated much of the cross talk din that diminished my enjoyment of music.

[davepellegrene]

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

Over the week I made up a set of the combo guides using the SS D2604 which I really liked after testing a few weeks ago. I installed one of them in one of the speakers, measured and worked up a crossover for it today. I still have the Audax TW025 in the other speaker. I played quite a bit of music today using them as a pair and I was surprised how good they sounded with unmatched tweeters. Imaging was good and I really had to listen closely to each one to hear a difference. Sitting back in the room I could not hear a clear difference. Moving up close to each speaker going back and forth I could hear some differences. I felt that the D2604 had a more natural sound and the TW025 had more of a crisper sound but at times to crisp if that makes sense. Also the ringing that I hear in the TW025 is not there in the D2604 so I've decided to move forward with it. I should have the other guide finished up and installed this week to get a better listen with both tweeters.

Here is a graph showing the Audax TW025 in red and the D2604 in black. Both measured with mid and woofer hooked up with crossovers in place. There are some differences in values along with some changes to reach a similar response.



Here is the D2604 Polar with crossover in place. Not quite as smooth as the Audax on the top end off axis. It could have to do with the fact the D2604 has a larger surround and I needed to back off a little on the guide because of it.



There is a noticeable difference in distortion between the two tweeters. I'm not sure if it has anything to do with why I like the D2604 a little better or not.

D2604 around 95 dbs with all three drivers crossed at 700 and 2100.



For comparison the Audax around 95 dbs with all three drivers crossed 800 and 2200




Dave

[Thumper Tom]

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

Man Dave, your testing is unmatched and what you do get repeatable results is amazing. The results you keep showing of the D2604 just makes me want to finish my build ASAP!!! :applause:

[Samppo]

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

Dave, the D2604 certainly performs exceptionally here. What size is the tweeter waveguide and how steep are the crossovers?
What seems a bit surprising is the high distortion with the Audax if we look at a previous measurement where it was crossed over at 1300 Hz in an 8" guide:
http://techtalk.parts-express.com/sh...87#post1953887

[davepellegrene]

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

The size of the tweeter guide is 8x5. Ive reworked this combo guide to get rid of the lines that were in between the other sets of guides. I also opened up the throat for the TB75 almost a 1/4" more.

Here are the slopes of the current crossover.


Here is a pic of the new guide with the D2604




Samppo,
As far as the distortion plot that you posted above of the Audax TW025. That was taken with the first set of drivers, that were not mine, which I mailed off with a set of guides. I will have to look into the distortion measurements with the combo guide, which were my set,to see what's going on. I'm not sure at this point if I have measured the distortion of both tweeters I have so it may only be one of them with the issue.

I did get the other combo guide into the other speaker. Hopefully tomorrow I'll get to listen to them.

Dave