[mr2dave]

Has anybody tried to model the new Mach 5 UXL-18 for an LLT build?
I'm trying to follow the basic idea laid out in the LLT Explained post, but I get a hump around the tuning freq. when I model a larger enclosure (~650L). I can't seem to get the desired 4db/octave roll-off above the tuning freq., either.
I can get rid of the hump by tuning lower and decreasing the enclosure size, but the roll-off above the tuning freq. is still only about 2db/octave and I don't know if any of this is okay.
Has anybody else already tried this? I did a search, but couldn't find anything helpful. =/

 

[gperkins_1973]

Mark told me that even 15 cu ft was too big for the UXL-18 driver. I need to have some play with it.

 

[Mike P.]

Some drivers don't need a huge cabinet for LLT performance, the UXL-18 is one of them. It models well in 340 liters (12 cu.ft.) tuned to 14 hz with 1200 watts. Output would be 115 db at 15 hz, plus any room gain.

 

[Mightywetfoot]

 

[Mightywetfoot]

 

[gperkins_1973]

Where did you get the bracing from as it looks like one off slot brace designs. No that is defo one off my designs without doubt. A great design I have to say.

 

[mr2dave]

Awesome. Thank you all for the help. I guess I should go get a driver ordered. =)

 

[gperkins_1973]

Port resonance on that model is too low in my opinion. It would be ok for a 60-70hz crossover but no higher. This is the main issue with certain drivers in a LLT configuration and that is keeping port resonance high enough and also keeping port velocity low enough. One fights the other.

I would suggest a port off 20.5" wide by 2" high by 47" long. Port velocity is at 33 m/s at 15hz but my current low tune is well over 40 m/s and no chuffing at all. 12 cu ft is not a small box so I can't see velocity off air being an issue.

 

[mr2dave]

Thanks for the tips, Graham.
I was having trouble trying to find a balance between port resonance and velocity. This will be my first build, and I don't want to screw it up.
It would probably be wise of me to just pay you for a design... I don't suppose you've already done a design for this driver.

 

[gperkins_1973]

Hi there,

I have done quite a few for the old Mach 5 Audio IXL 18" driver so it's just a case whether the dimension work with your space. I will have a look at them. I have done a 13 cu ft one tuned to 15hz which should work fine. Just need to check on the port. This was modelled with 700 watts as the old driver was less powerful. I need to check wether the port would cope with the extra power.

I will let you know.

cheers

Graham

 

[mr2dave]

Cool, thank you. I'm not really particular about dimensions. Whatever is best for the driver is fine with me.
It does look like 13 cubes gets the port resonance up closer to the desired level without pushing velocity too high.

 

[gperkins_1973]

I can modify one off the designs I already have to adjust the port and size if need be.

PM me your email and I will send you some pics/info.

cheers

Graham

 

[mr2dave]

Okay folks, I'm going to have Graham do a custom design for this one, and I'd like your opinions.
What cabinet size/specs (within the realm of possibility, of course) would you like to see?
My goal here is to arrive at a design that most people can live with, so other folks can save a few bucks on a pre-made design.

Here's where we're at right now:
The enclosue volume will fall somewhere between 10-15 cu ft.
Depending on the enclosure volume, it'll be tuned to 12-15Hz (bigger box = lower tune).

Which direction would you go with it?

 

[Mike P.]

I would go with 12 cu.ft. tuned to 15 hz with a 2.5" x 20" x 44" long port. First port resonance is 154 hz.

 

[Moonfly]

Okay folks, I'm going to have Graham do a custom design for this one, and I'd like your opinions.
What cabinet size/specs (within the realm of possibility, of course) would you like to see?
My goal here is to arrive at a design that most people can live with, so other folks can save a few bucks on a pre-made design.

Here's where we're at right now:
The enclosue volume will fall somewhere between 10-15 cu ft.
Depending on the enclosure volume, it'll be tuned to 12-15Hz (bigger box = lower tune).

Which direction would you go with it?

I started work on a data base with the aim of producing models for all drivers that would suit most people so people could go there for basic model ideas. There didnt seem to be demand so I stopped work on it though.

If you go with Mikes dimensions though, its a straight forward build. Not sure how well 12 cu ft would sit with most people though, and you may be best designing this to best suit your requirements.

 

[mr2dave]

Thanks for the help, Mike P. That sounds like it might just be the sweet spot.

Thanks for the advice, Moonfly.
It'll be a super-easy build for me no matter what, since I'll have Graham's plans. =D
Anything in the ranges mentioned will meet my requirements, I'm not too picky.

 

[gperkins_1973]

Whether you go for 11 or 12 cubes you will have a great sub. I designed a 10 cu ft mach audio sub for Gregg and he has built 4 off them!!!!!! Now that's commitment. Just let me know what you want me to do and I will get under way.

 

[mr2dave]

Of that, I have NO doubts, Graham. You've been very helpful so far, explaining your reasoning so that I can understand things that I just plain didn't know, such as the relationship between port resonance and crossover freqs.
I'll make a call relatively soon, but I'm in no hurry. It'll be a while before anybody has a driver on-hand, anyhow.

Do you have anything to add to Mike's wisdom?
I'm still not super-clear on what is gained or lost as enclosure size changes. I understand sealed enclosures, and I think I understand that a ported enclosure works pretty much the same way until a certain lower frequency limit, depending on the tune.
When I model it in WinISD, and I see the low-end SPL increase with enclosure size, along with excursion, while the top-end loses just a little. It looks like the port can be tuned as-needed to tame velocity, within cabinet size limits for a particular driver.
So, if I go too big and/or push too much power, I'll exceed excursion limits if I don't add a filter, which comes with it's own issues.
Am I more or less getting it? Yeah, I'm that much of a noob at this, for now =/

 

[gperkins_1973]

Dave,

I will email you in tomorrow with what I think.

Mike is a great guy and I did tell you he would suggest 11-12 cu ft so you will have a really great sub/s.

cheers

Graham

 

[mr2dave]

Cool stuff, Graham.

All I want to know from anybody/everybody is; How would you build it for yourself?

I do understand that there are a lot of variables involved, but I assume that a pattern should emerge from the answers to that question. Indeed, that had already started to happen.
The fact that I'm learning a lot about sub design along the way is just gravy. =)