Mach5Audio MJ-18 LLT - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 37 Old 01-23-07, 02:07 PM
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Re: Mach5Audio MJ-18 LLT

For large diameter ports, most of us use Sonotube. Where the port meets the MDF, we use a roundover bit to create a semi flare - the larger the bit, the better.

I agree that bass in the 30hz range doesn't get enough credit, that's where a lot of the more agressive and even stomach tickling stuff is. And I also agree that impact occurs much higher, in the 70-200hz range. That said, there is still a pretty noticable difference between 30hz stuff and infrasonic stuff. One is stomach tickling, the other is fear inducing. If one has a concrete floor though, the infrasonic stuff isn't very fun at all.


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post #12 of 37 Old 01-23-07, 02:23 PM
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Re: Mach5Audio MJ-18 LLT

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If one has a concrete floor though, the infrasonic stuff isn't very fun at all.
Why do you say this steve?
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post #13 of 37 Old 01-23-07, 03:54 PM
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Re: Mach5Audio MJ-18 LLT

yeh there is a difference between the 30Hz region and the infrasonic stuff, but on a low budget build getting a decent response that low that won't ultimately take performance away from the higher ranges is next to impossible, but not impossible, with some of the experience I've gained at DIYaudio forums I'd say that a horn is another choice is he wants low, but the sonotube seems best here, also another option that I'c ealways wanted to try myself is finding some tactile transducers like the Buttkicker 2 to go with this sub I want to get some cause I've felt them and even if you have a mediocre 10" sub adding one of these will bring those infrasonic frequencies to life because bass is felt more than heard the lower it goes and you'd have to have a wicked ear to be able to hear something like a 16 Hz tone.
 
post #14 of 37 Old 01-26-07, 11:26 AM
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Re: Mach5Audio MJ-18 LLT

One can flare PVC pipe by heating it gently with a heat gun then forcing it rather gently over a suitable mold. It doesn't seem to like being reheated though and can buckle easily. Which can waste expensive pipe. Don't try flaring PVC freehand. It needs a form to get the desired shape. I doubt you can make a full trumpet flare like the pro models. Wear thick leather industrial gloves as the heat required to soften PVC will burn your skin very easily. If you can't smooth the hot PVC with your hands then you're stuck!

There are some PVC fittings (joints) which I believe could also be used if they were cut away carefully to leave just a flare behind. The pipe adaptors look like potential flares as do the surface mounting drain fittings. You just need the imagination to make the most of what is on offer for other purposes. In larger sizes the joints certainly aren't cheap though.

Asking a drainage contractor on (or off) a building site might get you something cheap if you ask nicely and show respect. Or it might not. I had some nice clean 10" PVC from a very long length that had been run over by a tractor. My taking it away as it was I saved them burning it on-site. They were glad to get rid of it before the boss noticed! Sheer luck though.

MDF/chipboard/plywood rings can be added on the inside or outside of a sub and flared with a rasp or Surform tool. (a course wood file) I used to do this when I didn't own a power router. You can buy rough wood cutting tools to use in an electric drill to round over the most part of the flare. Then you smooth it off with files and sandpaper wrapped round a big dowel.

A dirt cheap Chinese power router can be obtained easily these days and the router cutting tools come in cheap sets too. A pro or serious woodworker might squirm at the quality but for occasional speaker and sub projects these tools last long enough to be worth the small outlay. I built my IB array using just such a router working slowly to conserve the tools. The router cost me the equivalent of $35 at an Aldi supermarket! My wife finally bought me a better quality Bosch router for Xmas.

I think 16Hz would have to be played at over 110dB for most people to be able to recognise it as a tone. Most subs produce enough distortion for the second harmonic to be audible and then they claim they can hear 16Hz when in fact they are hearing 32Hz.
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post #15 of 37 Old 01-26-07, 06:44 PM Thread Starter
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Re: Mach5Audio MJ-18 LLT

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One can flare PVC pipe by heating it gently with a heat gun then forcing it rather gently over a suitable mold. It doesn't seem to like being reheated though and can buckle easily. Which can waste expensive pipe. Don't try flaring PVC freehand. It needs a form to get the desired shape. I doubt you can make a full trumpet flare like the pro models. Wear thick leather industrial gloves as the heat required to soften PVC will burn your skin very easily. If you can't smooth the hot PVC with your hands then you're stuck!

There are some PVC fittings (joints) which I believe could also be used if they were cut away carefully to leave just a flare behind. The pipe adaptors look like potential flares as do the surface mounting drain fittings. You just need the imagination to make the most of what is on offer for other purposes. In larger sizes the joints certainly aren't cheap though.

Asking a drainage contractor on (or off) a building site might get you something cheap if you ask nicely and show respect. Or it might not. I had some nice clean 10" PVC from a very long length that had been run over by a tractor. My taking it away as it was I saved them burning it on-site. They were glad to get rid of it before the boss noticed! Sheer luck though.

MDF/chipboard/plywood rings can be added on the inside or outside of a sub and flared with a rasp or Surform tool. (a course wood file) I used to do this when I didn't own a power router. You can buy rough wood cutting tools to use in an electric drill to round over the most part of the flare. Then you smooth it off with files and sandpaper wrapped round a big dowel.

A dirt cheap Chinese power router can be obtained easily these days and the router cutting tools come in cheap sets too. A pro or serious woodworker might squirm at the quality but for occasional speaker and sub projects these tools last long enough to be worth the small outlay. I built my IB array using just such a router working slowly to conserve the tools. The router cost me the equivalent of $35 at an Aldi supermarket! My wife finally bought me a better quality Bosch router for Xmas.

I think 16Hz would have to be played at over 110dB for most people to be able to recognise it as a tone. Most subs produce enough distortion for the second harmonic to be audible and then they claim they can hear 16Hz when in fact they are hearing 32Hz.
Um, was this placed in the correct thread? I've made my own flared ports on many projects. I have a 3/4" round-over bit that will work nicely for the 6" port.
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post #16 of 37 Old 01-27-07, 02:51 AM
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Re: Mach5Audio MJ-18 LLT

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Um, was this placed in the correct thread? I've made my own flared ports on many projects. I have a 3/4" round-over bit that will work nicely for the 6" port.
Punkrokr15.5 asked about 6" ports a couple of posts above.... this is a thread about subs requiring large ports... I have a lifetime's experience in adapting simple manual skills and tools to woodworking and PVC fabrication problems on a limited budget using lots of patience.... so I volunteered some information ... is there a lack of bandwidth? Are there too many posts in the DIY section this week? Is the construction of proper flares common knowledge? Judging from my browsing around the subject of port flares it would seem not. A 3/4" roundover tool is not a proper flare....it is a bodge for low velocity ports.
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post #17 of 37 Old 03-08-07, 11:41 PM Thread Starter
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Re: Mach5Audio MJ-18 LLT

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Punkrokr15.5 asked about 6" ports a couple of posts above.... this is a thread about subs requiring large ports... I have a lifetime's experience in adapting simple manual skills and tools to woodworking and PVC fabrication problems on a limited budget using lots of patience.... so I volunteered some information ... is there a lack of bandwidth? Are there too many posts in the DIY section this week? Is the construction of proper flares common knowledge? Judging from my browsing around the subject of port flares it would seem not. A 3/4" roundover tool is not a proper flare....it is a bodge for low velocity ports.
No need to be testy. The biggest roundover bit I have is a 3/4, so it will work nicely.

Anyway on to more important things. I finally got my MJ-18 in the mail!! I was on my way to work and had my wife meet me at the post office with the SUV. We opened the double boxed package and when we saw how HUGE the 18" driver was my wife exclaimed,"That's crazy!" I replied, "No, that's awesome!" I never realized how big the driver was until I saw it. I can't wait to get started!!
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post #18 of 37 Old 03-09-07, 12:45 AM
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Re: Mach5Audio MJ-18 LLT

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I finally got my MJ-18 in the mail!! I was on my way to work and had my wife meet me at the post office with the SUV.
Congratulations.

I remember seeing an 18" Fane driver in a music shop window when I was a kid.

That was the biggest thing I'd ever seen. :holycow:

It looked just like a radio telescope.

You could walk round it and have a picnic on the other side.

Enjoy!
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post #19 of 37 Old 03-09-07, 03:25 PM Thread Starter
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Re: Mach5Audio MJ-18 LLT

Here's the MJ-18. It doesn't look big in the picture but it is. That's my 14yo son holding it. He took fifth in the State Wrestling Championships at 105lbs last week (can you tell I'm a proud dad). He won six matches (pinned five of his apponents) and lost two matches. Anyway, it's cold here but I hope to get started gluing up the plywood and mdf soon.

I ran some wires to it while the kids were playing xbox and it came to life. It may only have 12mm of excursion but it was moving like crazy. My wife came down stairs and stared at me. My daughters laughed and thought the driver moving like crazy was pretty neat. Shake the floor, shake the floor, woo hoo!
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post #20 of 37 Old 03-09-07, 10:48 PM
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Re: Mach5Audio MJ-18 LLT

He sure is surrounded by quite a few cute little girls there.
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