[dazzler9000]

I’m looking at building my own M&K MX250. I currently have a Monolith which is great, but then I was pointed in the direction of cheap M&K components from the USA.

I’m going to have to build my own cabinet. I’m looking at nicking the dimensions from the MX250 and 350 cabinets as I think they’re the same? My question is, how accurate do the dimensions need to be? I can get the external dimensions from the web, so I’m confident I could get pretty close. Would this be ok?

Is MDF the preferred material, if so which thickness? I know that you can buy sheets of oak veneered MDF, would this be ok? Unfortunately aesthetics are very important.

My brother builds bedroom furniture, and uses the wood that’s made from chipboard that’s covered in veneer, I thought this would be good as it could be had cheaply, but I was advised not to use this. If not, I guess I could look into veneering an MDF box. Anybody had any experience in veneering?

Anyway chaps, I’m a complete novice in sub building, so I’d appreciate any guidance and any M&K cabinet photos anybody has from their DIY build.

Cheers

[Moonfly]

Here is an example of an MK style push pull sub build.

Use the dimensions you got from the web, they will be correct for the MK drivers. IIRC the MK's I used looked to use 3/4 MDF and used no internal bracing apart from some additional internal pieces of timber on the inside of the corners. MDF is the best stuff to use, DONT USE CHIPBOARD.

Dont forget that with a true push pull design the speakers need to be wired out of phase so they move in phase.

[j0hn]

have you tried going to the source, and ask the man himself ? kkprofessionalsound.com

[dazzler9000]

Originally Posted by Moonfly

Here is an example of an MK style push pull sub build.

Use the dimensions you got from the web, they will be correct for the MK drivers. IIRC the MK's I used looked to use 3/4 MDF and used no internal bracing apart from some additional internal pieces of timber on the inside of the corners. MDF is the best stuff to use, DONT USE CHIPBOARD.

Dont forget that with a true push pull design the speakers need to be wired out of phase so they move in phase.

No problem, chipboards out..... So oak veneered MDF would be ok then. I'm fairly sure it's expensive, but I'll check it out.

As for wiring, I have no idea, I'll cross that bridge when I get all the bits.
Hopefully it should be straight forward??

Originally Posted by j0hn

have you tried going to the source, and ask the man himself ? kkprofessionalsound.com

I may drop him an email for cabinet schematics, but I don't know how keen he'd be to divulge them??

[j0hn]

If you dont ask him you will never know. Maybe hes more helpful than you realise. After all you are trying to recreate "one of his babies" so to speak. Plus he got rid of the company M&K. Just be honest and tell him what your doing and link to this thread so he knows what your up to. If he says yes your in luck, if he says no your still where you are now

[Moonfly]

Originally Posted by dazzler9000

I may drop him an email for cabinet schematics, but I don't know how keen he'd be to divulge them??

Given the circumstances surrounding the buy out of his company I dont think he'll mind much, he's very easy to talk too and a top guy . Wiring is straight forward enough, you just have to get i the right way round, which we can help with. MDF isnt that expensive, but not sure abut pre-veneered stuff, Ive not seen anyone take that route for a sub build myself.

[dazzler9000]

Ok, I'll drop him an email tomorrow.

The Veneered MDF is good stuff, I used it when I built my door frames in my lounge. It was a little trick the timber merchants told me about. Once it's in place it can be oiled to match the real oak. I'll give them a ring on Monday to check thicknesses and price.

I have to admit, I'm concerned about how good it will look, I really don't want it to look like DIY sub. I did see a youtube video the other day and iron on veneering looked a little bit easier than I thought it would, so I'm still open to offers.

[dazzler9000]

Update

I've decided I’m going to go with MDF and then veneer the box. I stumbled upon this thread Reveneering an old Speaker cabinet

I have to admit, I'm blown away by the finish, and I think it's stunning what you can do with some time, wood veneer and some skill.

Yep, I think I may be able to manage the veneer, not sure about the other two :rotfl

What's the preferred MDF thickness? I'm not really worried about weight. Is 3/4 inch best or thicker?

[Moonfly]

3/4 is quite common, and IIRC the actual subs are made from 3/4. On or two of us are using 1", but we're going with much larger drivers and larger boxes. I think you'll be fine with 3/4" but the final size is really your choice. Just dont use any smaller than 3/4" IMO, ive read it several times that using a brace mid panel is much more effective at reducing cabinet vibrations than simply increasing the thickness of panel.

[nad]

Out of interest, where are you getting the amp and drivers from? I'm in the process of trying to decide on a sub and this seems very interesting.

Thanks.

[dazzler9000]

Originally Posted by nad

Out of interest, where are you getting the amp and drivers from? I'm in the process of trying to decide on a sub and this seems very interesting.

Thanks.

Moonfly very kindly posted the info in another thread.

Originally Posted by Moonfly

This Cabinet:

Push-Pull 2X12 Sub-woofer Cabinet DIY Kit; Miller & Kreisel (M&K) MPS-5320; B-Stock, Black Matte

2 of these drivers:

M&K Miller and Kreisel 12" Woofer Model 17035 8 ohm

This amp:

MnK Amp

You would have to check availability, but IMO this would give an fantastic sub thats probably unbeatable for the money. The big SVS will still go deeper though. Also, you may require some minor DIY skills to complete the assembly, but it shouldnt be anything to difficult. May be of interest, hope it's of use.

Oh, and those links come from Ken himself

[Moonfly]

Originally Posted by nad

Out of interest, where are you getting the amp and drivers from? I'm in the process of trying to decide on a sub and this seems very interesting.

Thanks.

Just a heads up,

If your not planning on doing the push pull design in the MK style, then I wouldnt use those drivers. 12" Peerless XLS drivers are usually a favourite among DIY'ers with normal designs.

[nad]

Thanks for that guys, much appreciated.

Is the shape of the enclosure important for these drivers or is it purely the volume that is important. I can either build one that is identical to the 2500 but ideally i was considering a triangular box.

I may end up going with the Peerless drivers in the end but I just wanted to see what other options are available.

Thanks again.

[Moonfly]

Shape isnt that important, in fact a triangular design is considered better as it helps prevent standing waves inside the cabinet yadda yadda. Volume is the key, but if you go for the mk drivers you will need to copy their volume. If you use the peerless drivers you will have to work to the volume required for those drivers. We can help there if you need.

One other thing, the MK amp is tweaked to work best with the MK drivers (they say they are tuned to those drivers, with a Linkwitz transform circuit I believe), where as if your using the peerless drivers the end results may differ slightly, or you might have to monitor things like xmax more closely in relation to your box size.

No problems are impossible to overcome though, and there's no good reason not to use the (probably) superior peerless drivers.

[nad]

Thanks for that Moonfly. Much appreciated

[dazzler9000]

Right, components have been ordered.

I did email Ken and he was very helpful indeed.

I've decided on 1" MDF cabinet and then veneer afterwards. I remember seeing an mx2500 DIY build on here a while back and it has foam inside. Is this really needed?

What’s advised in way of internal bracing? I'm assuming you can just put a length of wood across the inside. Is thinner the better, so not to eat into the internal volume. Maybe 1x2" thick??

[Moonfly]

Best thing for bracing is a windowed brace from MDF, but you can use 3/4" or 1/2" if you wish. A windowed panel as a brace will brace along the entire side of the panel it is bracing because of line contact, rather than point contact of a strut brace.

Dont worry too much about losing a little volume, the simulation is a guide and driver parameters differ slightly between drivers anyway. You can use wadding inside the finished box to tweak the final performance, and this will account for a little volume lost to bracing.

I also put together a thread with some tips and links for DIY building, in there is a link to an enclosure volume calculator, which will also account for your bracing, so that will also help.

[dazzler9000]

Thanks moonfly, I’ll have a good read when I get some time.

I found these images from Brads excellent DIY build thread. Project M&K Sub

I hope it's ok to post them. Would you advise for more bracing, bearing in mind I'm going to be using 1" thick MDF all round?

Originally Posted by brad

Project M&K DIY sub MK 1.

This is a piece of 4" x 2" used for a cross brace the internal baffle itself 36mm thick acts as a very good brace

[Moonfly]

Good find

I searched high and low for examples of DIY MX subs (I'm building one with 2800 watts and 15" drivers)

I'll finish my post when I have more time . . . . .

cont . . . . . . .

FYI, IIRC, the MX subs themselves actually have very little inside them in the way of bracing. So I wouldnt overly worry about going mad with braces, perhaps one in the middle of the box.

[Nimby]

Correct me if I'm wrong but if that big port is only to let the driver breath then the box could be made much lower.

The lower part of the box (below the second driver baffle is just window dressing to disguise the presence of the dangling family jewels.

This arrangement allows both drivers to be front firing and it could easily be wall hung or pushed against a wall.

Bunging a reversed driver on the back to reduce distortion would be virtually the same idea. With the advantage of reaction force cancellation when using large drivers.

So we need two boxes from you with a full work up of REW, listening tests etc etc to prove that it makes zero difference to the sound to have the drivers at right angles.

Or the converse should it prove to be the case. (however unlikely)

[gperkins1973]

Dan,

2800 watts? Did you buy a different amp then cos the 4000 is 2 x 1250 watts rms in to 2 ohms.

cheers

Graham

[Moonfly]

Originally Posted by gperkins1973

Dan,

2800 watts? Did you buy a different amp then cos the 4000 is 2 x 1250 watts rms in to 2 ohms.

cheers

Graham

The EP 4000 is 2 x 2000 into 4 Ohms, link. Part of the reason I decided to drive from one channel is that is will give me exactly 2000 watts into the 2 1000watt rated drivers.

Dont know why I put 2800 , probably to do with the EP2500 I was originally looking at using. Sorry 'bout that.

[micb3rd]

Originally Posted by Moonfly

The EP 4000 is 2 x 2000 into 4 Ohms, link. Part of the reason I decided to drive from one channel is that is will give me exactly 2000 watts into the 2 1000watt rated drivers.

Dont know why I put 2800 , probably to do with the EP2500 I was originally looking at using. Sorry 'bout that.

No it is not 4000 WRMS no chance. You must ignore silly peak ratings which mean nothing.

The only figures you should belive is the ones in the manual that state clealy RMS into 1% THD on a sine wave is 1250 WRMS per channel at 2 ohms or 2400 WRMS when bridged mono into 4 ohms.

[Moonfly]

I usually do look into the manuals (see Onkyo 875 @ 140 watts per channel) . That said, the nature of subs would mean they are more likely to run quite low, then peak here and there wouldnt it?

I plan to jig things about and experiment anyway to see which method of powering my sub works best.

[stevefish69]

The maximum input current normally gives an indication on how much juice is available. the fact that the EP4000 can draw 2600 watts from the mains gives a good indication that it's capable of some serious output

[Moonfly]

Thats also about the limit of a 13 amp fuse isnt it?

[gperkins1973]

I have never taken the peak power into account for my sub only rms output. Even at 2400 watts my subs are only running at 22mm excursion. Mine are 27mm max. That means I have shed loads of grunt left. According to WinISD mine are good for 3700 watts to max excursion. With the BP upgrade I should be able to make the most of nearly 3000 watts rms. and that still is only 25.5mm excursion. God these bad boys are going to blow the house down. But as the plug will only be good for 2600 watts it is pretty irrelivant but it would be nice though.

Got my new sound card here now. I got the turtle beach Audio Advantage SRM card. Testing Will go ahead on saturday afternoon. Can't wait.

cheers
graham

[micb3rd]

Originally Posted by Moonfly

I usually do look into the manuals (see Onkyo 875 @ 140 watts per channel) . That said, the nature of subs would mean they are more likely to run quite low, then peak here and there wouldnt it?

I plan to jig things about and experiment anyway to see which method of powering my sub works best.

Peak power means nothing, there is no real way peak can be fairly measured across manufactures it is just a marketing number to make you want the amplifer more.

In the real way to RMS measure power is with a good solid load like a large bank of high power resistors.

You measure the DC resistace of the pack first (before it gets hot ). Then you attach a true RMS voltmeter to the amp terminals and a clamp ampmeter around the speaker cable for current.

Then hook up a o-scope to the terminals as well.

Then you run a 0db sine wave a though the amp inputs, then turn up the amplifer gain untill the the clean sinewave starts to clip on the o-scope, then you note the current on the ampmeter and the voltage on the voltmeter.

You then shut off the output and measure the resistance of the resister bank to check it has not gone up signifantly though heat. If the restance rised significantly on the test you will have to take that into account in your calcs.

You then calc power using the voltage, current and resistance values and you have a real power reading.

Bear in mind on music and movies you almost never reach a full 0db sine wave.

On a CD the loudest signal will be 0db (there is 96db of dynamic range) even very bassy music like Bass I Love You and the like will be recorded -3 to 4db down below the 0db limit that means an amp that puts out a true 1000 WRMS into a 0 db sine wave measured may only put out 400-450 WRMS on music at the same gain level.

Then factor in subwoofer coils getting hot so impedance rising, then enclosure impedance rise and amplifier power supplies sagging you begin to realise you never really get an amplifiers rated power on normal material.

[Moonfly]

Originally Posted by gperkins1973

I have never taken the peak power into account for my sub only rms output. Even at 2400 watts my subs are only running at 22mm excursion. Mine are 27mm max. That means I have shed loads of grunt left. According to WinISD mine are good for 3700 watts to max excursion. With the BP upgrade I should be able to make the most of nearly 3000 watts rms. and that still is only 25.5mm excursion. God these bad boys are going to blow the house down. But as the plug will only be good for 2600 watts it is pretty irrelivant but it would be nice though.

Got my new sound card here now. I got the turtle beach Audio Advantage SRM card. Testing Will go ahead on saturday afternoon. Can't wait.

cheers
graham

By another amp so you have one for each driver

@ micb3rd

TBH, I've never really been one to read all that much into watt ratings (just search my posting history), the only thing that made me choose the EP4000 over the 2500 I was going to originally go for was the fact I picked it up for £180 brand new with a hard flight case

Interesting insight into power though, one to bookmark I think, cheers.

[stevefish69]

Originally Posted by Moonfly

Thats also about the limit of a 13 amp fuse isnt it?

Not quiet - 3120 Watts is exactly 13 amps.

I would not worry too much about what the plug can deliver as it's only for very short peaks when it's asking for full whack. A time delay fuse can also help if you find the thing blowing.

My Cinepro is suppost to be on a dedicated 20-30 amp supply, but i've never blown a fuse, even when i've had it clipping in stereo. The lights in the house do dim when it's fired up until the caps are charged though