Deltalite II 2512- TB75 1558-AudaxTW25A8 Combo Waveguide

[davepellegrene]

I figured I'd start a thread for this build rather then post it in my " Two Way High Efficient" thread. I'm going to use the Audax for this build rather then try to push it to low in a 8" two way. I should be able to cross it to the TB75 1558 around 2 kHz. Ive not worked with the Deltalite II 2512 so I'm not quite sure were I will cross it to the TB75.

I got the double waveguide worked out pretty well. I mounted it to a piece of 3/4" MDF using silicone to attach it. Stiffened it right up. I'm going to set it into the baffle and attach it from behind.






Mounting plate for the drivers plus stiffening plate.




This is the back of the baffle with the guide set into it. I am going to facet the baffle edges so I will need to put two layers on the back. This is with one.




And the second layer




I made up a sled to cut the angles



Flip the sled around to cut the other side



Finished off with a hand saw

[davepellegrene]

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

Facets cut and cleaned up the hand saw cuts with a DA sander.




Baffle ready for drivers. Adding the extra two layers of 3/4" MDF keeps the Facet cuts in the baffle so the cabinet can be rectangular.



Dave

[craigk]

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

my initial thought was this thing is going to be ugly, I was wrong. I like the looks of this project. I hope the sound matches the looks, and I am sure it will.

[buzzforb]

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

Dave,
Excellent work on all fronts.

[Greggo]

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

My first thought was that it was going to look great, but it looks even better : )

Dave, you should really do two "voicings" on this design. One that sounds the most musical to you, and another one that is as close to neutral as possible without overly complicating the crossover design. For the latter, I think the guys over on gearslutz.com would just eat this up as a great alternative to the super expensive studio monitors that get all the attention. I think this has tremendous potential there, as well as folks here and on AVS that want a dynamic waveguide design but in a form factor that is much more WAF friendly, especially with folks like myself who want something nice flanking my TV because I don't have the option of hiding big boxes behind a projection screen.

I was really impressed by the response and polars you posted in other threads on this. Do you have any frequency ranges that you try to keep the crossover point away from, or do you believe that the math is best served and if well executed the crossover point shouldn't matter that much and will be undetectable by the listener? I ask because now that you have a mid, I have read many schools of thought on this. Some try to push down as close to 300 Hz as possible, while others move up to 800 Hz or higher, trying to leave the vocal fundamentals (300-800?) alone if at all possible. Then regarding the upper limits of the mid dome, some will stay under the 2-3 kHz range like you appear to be doing here, or some will push above and cross to tweeter at 3.2 - 4.8 kHz.... and I have read from many sources that from around 6k and up most listeners really can't localize and detect slight phase changes all that well, so crossovers in this range do well even though CTC driver distances would have some designers concerned about lobing.

Anyways, I am really very very curious about your findings and your final design with this combo, it just might tick a bunch of boxes for me in both technical and aesthetic terms. Nice work!

[augerpro]

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

Super cool concept Dave!

[davepellegrene]

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

My first thought was that it was going to look great, but it looks even better : )

Dave, you should really do two "voicings" on this design. One that sounds the most musical to you, and another one that is as close to neutral as possible without overly complicating the crossover design. For the latter, I think the guys over on gearslutz.com would just eat this up as a great alternative to the super expensive studio monitors that get all the attention. I think this has tremendous potential there, as well as folks here and on AVS that want a dynamic waveguide design but in a form factor that is much more WAF friendly, especially with folks like myself who want something nice flanking my TV because I don't have the option of hiding big boxes behind a projection screen.

I was really impressed by the response and polars you posted in other threads on this. Do you have any frequency ranges that you try to keep the crossover point away from, or do you believe that the math is best served and if well executed the crossover point shouldn't matter that much and will be undetectable by the listener? I ask because now that you have a mid, I have read many schools of thought on this. Some try to push down as close to 300 Hz as possible, while others move up to 800 Hz or higher, trying to leave the vocal fundamentals (300-800?) alone if at all possible. Then regarding the upper limits of the mid dome, some will stay under the 2-3 kHz range like you appear to be doing here, or some will push above and cross to tweeter at 3.2 - 4.8 kHz.... and I have read from many sources that from around 6k and up most listeners really can't localize and detect slight phase changes all that well, so crossovers in this range do well even though CTC driver distances would have some designers concerned about lobing.

Anyways, I am really very very curious about your findings and your final design with this combo, it just might tick a bunch of boxes for me in both technical and aesthetic terms. Nice work!

One of my goals here was to make a wide speaker not look so wide. The cabinet will measure 15" x 27". That was the main reasons for the facets to give the illusion the baffle is smaller then it looks. Secondly would be less diffraction. Rear mounting the Deltalite, which has a 12-1/2" wide frame, allowed me to cut the side bevels so the front flat section of baffle width is 12-1/4" wide. I have it inset into the back of the baffle 1/2" which puts the measured acoustic centers within 1/4". A big plus is keeping all the angle cuts on the baffle. This will allow the baffle to mount to a rectangular box.

I think I'm going to try a little different cabinet wall construction. I'm going to use the light weight panels that I used on my "Black Box" design but have the outer panel curved and the inner panel flat. I'm just not convinced I want a curved cabinet look.

This is the panel for the black box in case you don't know them. Between the panels gets filled with Denim insulation.

Bracing in the box

These are very light weight but very sturdy.

I was also a bit surprised by the polars of the mid/ tweeter. That is what made me want to pursue this design. The TB75 hold directivity down to about 400 Hz and that is also were the distortion starts to rise so I plan on staying above that point. On the top end I'll probably cross around 2 kHz. The Audax is good down to about 1.6 kHz in this guide.

As far as staying out of any ranges with the crossover I think it's pretty tough to do. I think a well executed crossover is the best way to go. I do pay a lot of attention to the polar plots. I try to keep a flat on axis and by adjusting driver slopes smooth out the 40 degree axis and the rest usually falls in line. Once I get to that point I drag out my Continuums and try to match the vocal range.

My first try with the double guide was pushing them closer together. They had a CTC of 4". This created a sharp edge between the guides which treated diffraction mostly in the tweeter. Spreading them apart to a 5.5" CTC smoothed that right out. If I were to mount these drivers on a flat baffle they would have a CTC of 5".

This is the distortion on the TB75 at 90 dbs with EQ on the bottom end to what I thought was acceptable distortion. You can see it starting to rise at 400 Hz.



This is the Polar plot with the XT25 for the top end.


I'm in hopes of keeping the sensitivity between 92-95 Dbs. It's going to hing a lot on the Deltalite. It's rated at 99 Dbs at 1w/1m. I'm just not sure how much baffle step I want to put on it. I plan on crossing to a sub at 80 Hz so I was thinking about going sealed. That would put the TB75 as the week point. It's rated at 90 Dbs sensitivity but with the guide boost and possible help from the woofer and tweeter I should be able to get it up to 92-95.

If this design shows interest I will probably make the guides and baffle available. I could offer just the guides, guides and baffle or a complete kit. Don't want to get the horse in front of the cart though.

Dave

[davepellegrene]

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

my initial thought was this thing is going to be ugly, I was wrong. I like the looks of this project. I hope the sound matches the looks, and I am sure it will.

I wasn't to sure myself! I plan on covering the baffle in cloth like I did on these.
I was thinking light grey but I will probably go black



Here is the light grey



Dave

[davepellegrene]

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

Super cool concept Dave!

Thanks,
I haven't had a chance to do the comparison between the B&C's and Fatail Pro's yet. I'll be doing that this week. I ordered the AST2560's last night so I'm going to mate them up with the B&C's. I'll get them back to you soon.

Dave

[winslow]

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

You should try the Celestion CDX1-1425 compression driver at least once.

[davepellegrene]

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

You should try the Celestion CDX1-1425 compression driver at least once.

What do you think the advantage would be over the AudaxTW25A28. Looking at the stats on PE's site the Celestion's are in the same price range. They have a sensitivity of of 108 dbs vs the Audax at 95 dbs. What confuses me is the recommended crossover is 2.5 kHz. Looking at the graph they go down to 1.0 kHz. Not sure what the distortion would be. That may be why they recommend 2.5 kHz. Just curious why you think I should try them.

Dave

[craigk]

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

[QUOTE=davepellegrene;1977027]I wasn't to sure myself! I plan on covering the baffle in cloth like I did on these.
I was thinking light grey but I will probably go black

man that black looks good on that design. +1 for black. the audax is a great tweeter, really overlooked.

[winslow]

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

Heard nothing but good things about them. Plus you are getting into high efficiency midbasses, why not try a nice little compression driver too? If you didn't like it, they would sell pretty fast...pretty popular little driver. They are very clean drivers after 2k from the measurements that I have seen.

That's all. Just something to think about.

Nothing wrong with the Audax for sure...and they do look cool with the gold dome.

[winslow]

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

And that is one seriously good looking speaker you are making!

[bigfishe]

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

How much would you charge for a waveguide for the css ldx25
And the tb mid?