Is it possible to cover the whole spectrum, high spl, low distortion with a 2-way?

"broadband characteristics" what is this?

TD-4001 is rated from 600Hz-20k. How can this be x-over-ed at 425Hz?

Could be possible the JBL Hartsfield could use 400Hz or 500Hz as a crossover point. The TAD and JBL drivers are similar. Depends on the raw response on the horn. I thinks it's pushing things to say the least as the excursion is going to fatigue the diaphragm surround if you drop any real power into them.

Rob :)
 
"broadband characteristics" what is this?

Having a mother-toungue which is a little similar to his I guess he wanted to say that the lower you cross the more the whole system will behave like a wideband driver. I can beleive that. On my large MTMs the sound does also seem to come from the horn alone. Even with bass-heavy music. And this is also what the OP likes to achieve.

Regards

Charles
 
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Seems like 800hz is about right for the Axi no less than any proper 4" compression driver, with exception that the Axi would have better midrange or slightly lower extension, via slightly more excursion ability. I'll gamble and say that Axi has about 100hz more extension than the alternative compression driver. 300hz vs 400hz with a horn for pro use.
Camplo,

"Pro use" is a rather vague description, though I'd agree the Axi2050 has an extension of 100 Hz lower than an alternative 4" diaphragm compression driver such as the TAD 4001 or the current 4002.
Both the plane wave measurements and those drivers on the Klipsch K402 horn (roughly conical with tractrix secondary flare, about 35.5 inches wide, 21 inches high, 17 inches deep) show those response differences.
AXI2050vsTD-4002.png

On the K402, the TAD 4002 is +/-3dB from 400 to 4kHz, while the Axi2050 is +/-3dB from 300 to 3kHz.
 
Regarding the xmax / mechanical limits of the AXI driver...I've some experience thrashing on them on K402's and 2360A's with test signals. Provided you aren't running them full power below 300Hz you will not want to be in the same room with them if they are being driven hard enough to approach mechanical limits. I don't know where that limit is. These are very "hardy" units. I didn't go past roughly 23 volts. Ear plugs under shooting muffs wasn't enough. Distortion jumped up below 350Hz with the 2360A and below about 400Hz on the K402. 500Hz min or higher XO would be best for BIG environment "Pro" work. The WG the CD is attached to is a major factor in the performance of course. YMMV.
 

camplo

Member
2019-02-25 2:27 am
Thanks for the info @Josh Ricci ! That is very telling. Distortion wise, how low do you think an Axi could be used with a Waveguide?

I don't know where that limit is

That makes 2 of us :ROFLMAO: I would think that still the XO is going to be approximately 800hz, unless somehow the Axi sounds acceptable with the extension used at the same time with 20khz in mind. At the 85db listening average it might be able to do it just fine.



On my large MTMs the sound does also seem to come from the horn
I've been playing with the woofer section of the system. With a little tweaking, the drivers sum very well at close distance. I think this is a very good sign considering the distance of the drivers vs my listening distance, approximately 40 inches or so. I am experimenting in the temporary space for experience points. I have learned that the FR of my amps are not equal per channel. The amps have its own diagnostic tools and after hooking both subs for the first time it was obvious one had more oomph. Turns out the channels FR was unique to other channel....I have like 6 of these amps, I'll go through them and see who has the best FR sell the rest.....or keep them for parts.

I can see running 2 amps for mid and sub bass, and having some other smaller amp for the compression driver, though 32 bands of eq is appetizing.

I've been recommended the Motu Ultralite mk5 8 channel pro DAC. Sounds like a good choice considering the goal of FIR filtering per channel. 8 channels is just enough for the 6 up front and 2 rear subs. Nice coinkydink

Bass solos are perfect for the part of the system I am learning currently. Goal being, make the 2 speakers sound like one. I think anyone who builds something similar, this is going to be pleasantly surprised. The BandPass PPSL is a very good influence on the lower bass, maybe due to help of hiding mechanical noises. I've been sort of A/Bing between the large woofer section and my small two ways.
 
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Bass solos are perfect for the part of the system I am learning currently. Goal being, make the 2 speakers sound like one. I think anyone who builds something similar, this is going to be pleasantly surprised. The BandPass PPSL is a very good influence on the lower bass, maybe due to help of hiding mechanical noises. I've been sort of A/Bing between the large woofer section and my small two ways.
Victor Wooten. Listening to him is a spiritual experience. He wrote a fine book too - "The Music Lesson". I recommend it to anyone at any music level.
 
I used 4 different woofers with my horns over the years, and in each case the sound was much better pushing the crossover lower. To the point even of providing some eq as horn cutoff was reached in order to extend it lower. My 800 watt amps on the woofers flicker distortion lights often during listening, and the horns still sound great keeping up and have never been damaged. And I'm using a 1.4 inch cd. My prediction is that you will prefer a low xo on that axi for home use. I bet 400ish if your horn can do it, maybe even lower. You will notice the difference with voices especially.
 

camplo

Member
2019-02-25 2:27 am
Its funny the mouse wheel my brain is doing.....15" coaxial in MTM with 18"s or bigger even...
If according to my calculations @GM the xmax of a 604 style coaxial is about 4mm? So if I keep excursion below 2mm which was my intent anyways....no THD right? No worries of THD from the compression driver?

For curiosity sake.


Have a read! :) We are getting buried in snow today!

http://www.gedlee.com/Papers/THD_.pdf

http://gedlee.azurewebsites.net/Papers/Distortion_AES_I.pdf
 

camplo

Member
2019-02-25 2:27 am
I chose bandpass over sealed or BR/TL.....My ports are 26x5.5 how big are yours? Or is that supposed to suggest that I am limiting my headroom/extension by not using the back wave.

I think I have a good thing so far, can't really see the whole image until the horn arrives. Each config has its cons and pros....with TMW you can can get the whole spectrum bandwidth/headroom. With MTM you get the central sound source, and with TMM you are somewhere in the middle with still not enough bass extension.
2.5way with the large TMM is a really good place to be. Thats about where I am at, except for a slight high passing on the middle woofer.

Still the symmetrical/centrical presentation of a large portion of the spectrum is a desirable thing I feel, mainly because mid/bass is locatable, and the area above the HF comes across just as empty as the space is above it lol.
 
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I used 4 different woofers with my horns over the years, and in each case the sound was much better pushing the crossover lower. To the point even of providing some eq as horn cutoff was reached in order to extend it lower. My 800 watt amps on the woofers flicker distortion lights often during listening, and the horns still sound great keeping up and have never been damaged. And I'm using a 1.4 inch cd. My prediction is that you will prefer a low xo on that axi for home use. I bet 400ish if your horn can do it, maybe even lower. You will notice the difference with voices especially.

Yep, CD's taken lower has definitely been a design goal in numerous builds lately. I know i sure have played with that alot.

What if find interesting is trying to guess why crossing over lower sounds better.
On the surface it would seem either the directivity curve improves;
or distortion, THD, IMD, whatever, decreases;
or getting as much bandwidth as possible into a point source, simply sounds better.

Personally, i feel xover point based on directivity, is pretty much fixed by geometry. So if a SQ gain is due to directivity improvement from moving the CD xover lower, it just means xover wasn't correctly chosen to begin with. I toss this out as a valid reason for lowering CD xover.

I do believe getting as much bandwidth as possible into a point source or perhaps better said, a quasi-point source, simply sounds better.
This opinion comes from working on MEHs and comparing them to a number of different type builds and commercial speakers that were all well executed.
I give lowering the CD xover point a lot of value here.

But then it get's real interesting to me....
Let's ay i'm willing to run the CD at low enough SPL that I can safely take its response very low...like 300Hz or so.
Will it sound best taken as low as possible? (and ignore directivity concerns by comparing outdoors)
My experience is no, it won't.....that there is a trade off between the CD getting marginally worse as it goes lower, compared to the cone driver getting marginally better. That the tradeoff has an equilibrium point and going any lower with the CD worsens the sound.

Purely subjective assessments and evaluations...i know.

But the idea of that tradeoff, that past a certain point a CD gets worse as it goes lower, and that the cone driver it's mating with gets better as it goes lower........pushed me to say hey, there needs to be an intermediate driver to solve that.
I mean heck, isn't that the whole reason for multi-ways existing?....
Use as many driver sections as needed and let each driver section do what it does best...

Anyway, i don't try to take a CD as low as possible anymore.
The AXI if i had one? ....probably 500Hz lowest, maybe higher.
My dcx464 and 4594HE's....i'm up to 900Hz, with small mids bridging the gap down to low-mid woofers at 300Hz (which pass off to subs at 100Hz)
The clarity improvement of the combined CD and mids crossed at 900Hz is remarkable, vs eliminating the mids and running the CD straight down to low-mids anywhere between 450-700Hz. (All on the same box apples to apples).
my 2c experiences
 
I chose bandpass over sealed or BR/TL.....My ports are 26x5.5 how big are yours? Or is that supposed to suggest that I am limiting my headroom/extension by not using the back wave.

I think I have a good thing so far, can't really see the whole image until the horn arrives. Each config has its cons and pros....with TMW you can can get the whole spectrum bandwidth/headroom. With MTM you get the central sound source, and with TMM you are somewhere in the middle with still not enough bass extension.
2.5way with the large TMM is a really good place to be. Thats about where I am at, except for a slight high passing on the middle woofer.

Still the symmetrical/centrical presentation of a large portion of the spectrum is a desirable thing I feel, mainly because mid/bass is locatable, and the area above the HF comes across just as empty as the space is above it lol.
Cool sounds like you've been gaining a lot of focus.
My PPSL ports are 20x8.5. I didn't know yours had ports...thought you were sealed....thought you were against ports due to group delay concerns....pls excuse.