Mach 5 MJ-18 EBS Sub? (Maybe)

[kano32]

I am on a strict budget ($100 for driver) and already have a Bash 500 amp from PE. I am thinking of using the 18" sub from Mach 5 Audio. I live in Alaska and I haven't been able to find a large sonotube so I was thinking of a verticle rectangle around 19"x19"x44" with a 6" port 22" long.

Here are the T/S Parameters: MJ-18 - 4 Ohms

Fs = 28 Hz
Re = 3.2 Ohms
Qes = 0.34
Qms = 4.99
Qts = 0.31
Mms = 229 grams
Rms = 8.1 kg/s
Cms = 0.14 mm/N
VAS = 208.4 litres
Sd = 1029.2 cm2
Xmax = 12 mm
Cone Diameter = 36.20 cm
Power Handling: 600 Watts
SPL (2.83v/1m): 93.4 db

Recommended Box Sizes (this is from Mach 5 site):
Sealed: 80 litres (2.8 cu. ft.)
Ported: 128 litres (4.5 cu. ft.) 30Hz tuning
**EBS: 250 litres (8.8 cu. ft.) 18Hz tuning** (thinking of this one)

Any thoughts?

[ThomasW]

That driver probably doesn't have enough Xmax to pull off a really low tuning.

If you have space for the EBS box you could experiment with different port lengths using PVC pipe and couplings.

The price has gone up for the driver. So you should check with Mark to see if it hits your $100 with shipping.

[kano32]

That driver probably doesn't have enough Xmax to pull off a really low tuning.

What lower cost driver would you recommend? I can raise my budget some but I can't spend $300 at this point.

[ThomasW]

There's nothing I know of in the $100 range.

I'm not saying it won't work. You'll just need to be a bit careful with high SPL. Also be careful not to 'unload' the driver playing loud frequencies below Fb.

[kano32]

If you have space for the EBS box you could experiment with different port lengths using PVC pipe and couplings.

I have plenty of room for an EBS box. What would experimentation do for the design? What is the goal of different port lengths and couplings?

[ThomasW]

As the port length changes so does the tuning. With couplings you could adjust the tuning and optimize it for the mj18 and your program material.

If you don't run a lot of material with subsonics then you'd probably want a higher Fb and enjoy potential higher output levels. If you're running a lot of subsonics then you'd want a lower tuning to protect the driver from unloading.

[clearwaterms]

you could look at the adire tempist. It's $150, but it should work as a down firing in an EBS.

I might be wrong on this, BUT, one thing to keep in mind with a rectangular box vs. a tube like the sonotube is to use alot of reinforcements, with a tube it isn't as needed.

[ThomasW]

There's quite a bit of difference between using a 12" and an 18".

Also other than warranty replacement, Adire/CSS offers no service for these drivers. This means they won't recone a driver if it fails, so your stuck with a paperweight and buying a new driver.

I know Mark at Mach5 does stock reconing kits for his drivers.

[kano32]

Well, I'm still not sure which driver I am going to buy but I did go to Home Depot today (had Christmas giftcards to spend) and bought some 13 ply oak veneer plywood. I've always used mdf+paint or mdf+veneer, its time to try some plywood.

The cost of the plywood was more than mdf but less than mdf+veneer, soooo I'll try it.

[kano32]

Hey Thomas,

Thank you for all your help so far! Please sir, can I have some more? ops:

I plugged in the MJ-18 into WinISD Pro and came up with an ESB 7.7 cuft tuned to 25Hz. How does that sound? That isn't tuned as low as the 8.8 cu ft recommended by Mach5.

Since money is an issue right now (I just financed a new horse trailer for my wife) actual cash is hard to come by. I think I am going to go with the MJ-18 and my Bash 500.

Any comments from anyone would be appreciated.

[Jerm357]

I am on a strict budget ($100 for driver) and already have a Bash 500 amp from PE. I am thinking of using the 18" sub from Mach 5 Audio. I live in Alaska and I haven't been able to find a large sonotube so I was thinking of a verticle rectangle around 19"x19"x44" with a 6" port 22" long.

Here are the T/S Parameters: MJ-18 - 4 Ohms

Fs = 28 Hz
Re = 3.2 Ohms
Qes = 0.34
Qms = 4.99
Qts = 0.31
Mms = 229 grams
Rms = 8.1 kg/s
Cms = 0.14 mm/N
VAS = 208.4 litres
Sd = 1029.2 cm2
Xmax = 12 mm
Cone Diameter = 36.20 cm
Power Handling: 600 Watts
SPL (2.83v/1m): 93.4 db

Recommended Box Sizes (this is from Mach 5 site):
Sealed: 80 litres (2.8 cu. ft.)
Ported: 128 litres (4.5 cu. ft.) 30Hz tuning
**EBS: 250 litres (8.8 cu. ft.) 18Hz tuning** (thinking of this one)

Any thoughts?

Are you talking about an enclosure something like this :B :B :B

http://www.htguide.com/forum/showthread.php4?t=22170&highlight=rl-p15

[kano32]

Yup Jerm357. I just can't afford a Rl-p driver at this point. I just want a sub to get me by until I finish my HT room and build an IB sub.

[ThomasW]

I'd go with the 18Hz tuning. There's just to much program material below 25Hz, so you risk having the driver unloading.

[kano32]

I'd go with the 18Hz tuning. There's just to much program material below 25Hz, so you risk having the driver unloading.

Well, I'm going for it. I'll build the 8.8cu ft enclosure: 19"x19"x44" internal volume, plus a 6" x 21.5" port.

Hopefully by the time I finish the enclosure I will be able to afford the driver and dampening material.

[kano32]

Hey ThomasW or anyone,

I was thinking of mounting the driver forward facing at the bottom of the vertical enclosure instead of downfiring. Any thoughts on this?

[ThomasW]

Hey ThomasW or anyone,

I was thinking of mounting the driver forward facing at the bottom of the vertical enclosure instead of downfiring. Any thoughts on this?

Operationally there's no difference. It's much easier to protect the driver if it's on the bottom

[WillyD]

Regardless of the size, a 10" port is really not necessary for this sub. It has only 12mm of excursion with an sd of 1029cm^2.

Even at max power, with the highpass set properly and using a 6" port, he will not experience chuffing/port noise.

A larger enclosure would be nice, sure, but I agree with Thomas. Building a much larger box like that is crazy.

[ThomasW]

Three posts in this thread have been removed by the moderator.

Willy's comment refer's to something talked about in one of the deleted posts.

[WillyD]

I thought I was going crazy.

[mrogowski]

Yup Jerm357. I just can't afford a Rl-p driver at this point. I just want a sub to get me by until I finish my HT room and build an IB sub.

Dare I say it, but you may not need anything else...

Listen to these guys, they know what they're saying.

Best,
Mark

[kano32]

Well, I took the plunge. I just bought a MJ-18 and put it on the credit card. It's coming from Canada and going to were I live in Alaska so I hope it doesn't take too long to get here. It's time to cut wood!

[ThomasW]

Might take a long time to arrive if it goes by dog sled.... :B

[kingpin]

Might take a long time to arrive if it goes by dog sled.... :B

Canadian jokes all over the board today. EH! :

[technimac]

Dog Sled priority post

The way the snow's been coming down, dog sled will probably be the fastest and most reliable mode of transport to either Alaska..... or Colorado. :W

[mrogowski]

Just pass me a beer...

[Hdale85]

I know its a little late but these are pretty inexpensive and 99 bucks for the 10" 135 for the 12" and 20mm of xmax.

http://www.tcsounds.com/db500.htm

Ah nevermind he bought an 18" driver 12 and 10 inches is quite a bit smaller.

[kano32]

I know its a little late but these are pretty inexpensive and 99 bucks for the 10" 135 for the 12" and 20mm of xmax.

http://www.tcsounds.com/db500.htm

Ah nevermind he bought an 18" driver 12 and 10 inches is quite a bit smaller.

Yeah, I did. I visited HomeTheaterShack forums and a couple of guys used four of the MJ-18 in an IB sub with great results.

I went with one MJ-18 because it's going to be a long time before I get my HT room drywalled. I have to drywall a bedroom, bathroom, family room and laundry/utility room before I drywall the HT room. So in my makeshift HT room I still want to shake the floors and get my wife to yell at me. :T I'm sure that the MJ-18 will do a great job in the bass department and fill my needs until I use four MJ-18 in an IB in my crawl space. :twisted: That should really make my wife go nuts. Well, I'm off to heat up my shop and cut some oak plywood!

[kano32]

Might take a long time to arrive if it goes by dog sled.... :B

I'm not too worried about it. Canadian dog sled driver's are used to delivering packages to igloos. I've got my igloo marked well and I have a seal oil lamp burning 24/7 until the MJ-18 arrives at it's new home.

It's funny how people picture Alaska. I live in the Mat-Su Valley (Matanuska Susitna river valley) which is 30 mile north of Anchorage (our biggest city). Our winter's aren't too bad and sometimes I see temperatures in the Lower 48 that are lower than ours. The only difference is our winter lasts longer than the Lower 48.

Well, I'm wasting time typing. I'm going to go cut wood!

I love the smell of sawdust in the morning, smells like.... woodworking.

[ThomasW]

My best friend used to live in a cabin on the way to Hatcher Pass.....

[kano32]

My best friend used to live in a cabin on the way to Hatcher Pass.....

It's a small world isn't it? Do you know if he live on the Palmer side or Willow side?

[ThomasW]

Don't remember exactly where the cabin was, I didn't make it up to Alaska in time to see it.

He was a welder who originally went up to work on the Alyeska pipeline. He decided to work at a welding shop in Anchorage instead. Kept a apartment in Anchorage and had the cabin built.

He was an 'extreme' hang-glider pilot. Some 25yrs ago he was killed by a freak gust of wind while going off a big cliff near Hatcher Pass

[kano32]

Well I got a call from Mach5Audio and the 4 Ohm version of the driver is out of stock. He said that the drivers should be in by the end of the month. That should give me time to finish up the enclosure (which I didn't work on yesterday).

[kano32]

I found out how to copy the screen by reading another post on the forum, so I decided to make a screen capture of WinISD.

[kano32]

I spoke to Mark at Mach5Audio and he thought that I could use up to 1000 clean watts to drive this driver. I was planning on using the Bash 500 amp that I have but I may want to overspend my budget and go for a larger amp. Any thoughts on the additional power on this design?

[ThomasW]

I would be a little careful since the Xmax is only 12mm.

If the eventual plan is to put in a higher excursion driver, (remember Mark is developing a more "manly" 18"), then yes I'd start with a bigger amp

[clearwaterms]

I would be a little careful since the Xmax is only 12mm.

If the eventual plan is to put in a higher excursion driver, (remember Mark is developing a more "manly" 18"), then yes I'd start with a bigger amp

If you were to recommend a bigger amp, and on a budget, what would it be?

[ThomasW]

There is no bigger amp on that budget.

[clearwaterms]

There is no bigger amp on that budget.

if you were to stretch the budget, what would be the next amp up, plate / rack mount / otherwise?

I am just curious?

[kano32]

if you were to stretch the budget, what would be the next amp up, plate / rack mount / otherwise?

I am just curious?

Most of the pro sound amps or plate amps around 1000 watts are around $300. I think I am going to try using my Bash 500. If I'm not satisfied then will save for an amp that I can use for this design AND an IB sub in the future.

[kano32]

How about 2 MJ-18's

Well, since I am waiting for the 4ohm MJ-18's to be restocked I did a little thinking. What if I made my box a little larger and placed 2 MJ-18's in it. Check out the screen capture from WinISD.

ThomasW or anyone with thoughts?

[Jerm357]

Would be better if you could post a graph for the spl instead of the transfer function magnitude one.

[kano32]

Would be better if you could post a graph for the spl instead of the transfer function magnitude one.

Ok, here it is.