Fixing the PE boxes

Danny Richie · « **on:** 7 May 2008, 01:14 am »

I am about to release 3 new mini-monitor kits.

For these new kits I wanted to see if the inexpensive cabinets from PE could be used. They can be used but require some work.

Keep in mind that the actual air space listed for these is not accurate.

PE's boxes listed as .38 cubic feet are actually .314 cubic feet.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-717

PE's boxes listed as .5 cubic feet are actually only .376 cubic feet.

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-727

The brace down the middle of the box puts quite a bit of reflective surface area right behind the woofer. This really must be removed.

I found that most jig saws will just fit into the box enough to cut the center of the brace right out. What's left still does a good job of stiffening up the side panels.

I also stuck the die grinder in there and took the sharp edges off the brace as well.

The nicely curved sides are actually plywood. So some sort of resonance control goes a long way toward keeping the box quiet. Lining it with the No Rez takes care of the resonance and hides what's left of the brace.

The back is just wide enough to accommodate the flare of the 2" PSP port.

The larger box with port was just large enough to make use of our M-130X woofer. In combination with the new deep back cup Neo3pdr this new kit is a killer little mini-monitor. It will be one of those giant killers in a big way. Look for more info on the Neo-1, Neo-1X, and Neo-2X kits shortly.

There are already two holes in the back cut on a 3/4" spacing. So reaming them out with a slightly larger grill bit allows the Vampire binding posts to slide right in. I will be making the solid Copper Cardas posts and option as well.

If you want to use a less expensive GR binding post cups then you can cut that section out and mount the binding post cup in its place.

Of coarse you still have to cut the front baffle on these boxes, but with a little effort you end up with a pretty decent box for what they cost.

The veneering looks pretty good too.

I'll have regular drawings for box plans for all that would like to make their own boxes for these kits, but for those that don't want to build their own boxes this looks like a a decent option.

These boxes could be used for our A/V-1 kit as well.

pbrstreetgang · « **Reply #1 on:** 7 May 2008, 01:35 am »

Looks great Danny!

FredT300B · « **Reply #2 on:** 7 May 2008, 01:39 am »

The woofer is surface-mounted, right? So the only thing that needs to be recessed is the tweeter face plate, right? This should be much easier for most than building the enclosure from scratch. If anybody in the Houston area wants to build a pair, I have a plunge router and would be glad to help you with the driver and port cutouts. Free of course. Just PM me.

dorokusai · « **Reply #3 on:** 7 May 2008, 01:57 am »

That looks very interesting Danny and I look forward to checking out a pair down the road. My homeboy Russ chats you up quite a bit when we start talking about DIY stuff and why we're so lazy and unmotivated. Great work!

Mark
Polk Audio CS

HT cOz · « **Reply #4 on:** 7 May 2008, 03:20 pm »

Dang those are looking good!!!

Nick77 · « **Reply #5 on:** 7 May 2008, 03:35 pm »

Wow! Those look awesome. I assume those would be the perfect companion to my OB-7's as rear duties?

Danny Richie · « **Reply #6 on:** 7 May 2008, 03:47 pm »

Quote

Wow! Those look awesome. I assume those would be the perfect companion to my OB-7's as rear duties?

Yes, they match very well.

Martyn · « **Reply #7 on:** 7 May 2008, 04:32 pm »

Over Christmas I built two pairs of speakers using the Neo 3PDR and M130 in PE’s curved 0.38 cu. ft. boxes. I didn’t trim the centre brace, but I still found some annoying resonance which I reduced to an acceptable level by adding some constrained layer damping. Using No Rez would be easier as long as it still does the job. My boxes were made of laminated layers of MDF, not plywood, but maybe the design has been improved since then.

Interestingly, there were some minor differences in the construction of the two pairs, but nothing that should make any difference to performance. One of the grills was half an inch bigger than the other three which was a source of annoyance, but it’s the sort of thing that no-one ever notices once they’re in place (even if you choose to use them).

The rabbet on the baffle that locates it in the box has a slight taper on it which ensures a snug fit and probably helps to reduce leaks. I thought this was a nice touch. The baffle is thick enough and the Neo tweeter thin enough for the cut-out to be routed as a recess – it doesn’t need to be cut all the way through.

Overall I am pleased with the result – both pairs look and sound good (I particularly like the cherry). I agree with Danny’s assessment that the boxes do need some work, but it’s not very much and is well worth the effort.

Danny Richie · « **Reply #8 on:** 7 May 2008, 07:20 pm »

It could be that these are laminated layers of MDF as well. It is hard to tell. You can see the edges of the lamination above.

Another thing I noticed was that some of these used a really dark and soft MDF while others used a harder and lighter colored MDF.

laserman · « **Reply #9 on:** 18 May 2008, 06:22 pm »

Danny,

Would this cabinet work better - to get the right internal cubic volume ? Since the published number was short on the .5 and it appears critical to the overall sound signature, it seems this one may do a better job. I thought even though this is taller, the baffle is narrower and one may be able to use a front port? And if the volume does work out better, would you recommend it for the Neo X1 or Neo X2 kit or either ? What affect will this larger volume cabinet have ?

Parts Express Dayton MTMC-0.75MA .75 ft³ MTM Curved Cabinet Maple
Dimensions: 20" H x (8" Front, 4.5" Back) W x 13" D.
Attractive curved-sided design is extremely rigid and reduces diffraction
Very tight-grained, real wood maple veneer
.75 ft³ net internal volume
Exclusive baffle replacement system
Magnetic grill fasteners

Regards,
Lou

Danny Richie · « **Reply #10 on:** 18 May 2008, 07:34 pm »

You mean this one?

If they are consistent with the curved sides and based on internal measurements of the smaller box then this one should be about .585 cubic feet. Minus the port, back of the woofer and crossover and you will be about .55 cubic feet.

This box is not wide enough for the M-165X woofer but the M-130X woofers will fit the baffle. However optimal ported enclosure for the M-130X woofer is .4 to .45 cubic feet. So you'd have to do something to take up the added air space.

See box plans for the Neo-1X: http://www.gr-research.com/pdf/Neo-1X%20box.pdf

laserman · « **Reply #11 on:** 18 May 2008, 10:48 pm »

Hi Danny,

Yeah, that's the one. I got the discription right but not the picture. I'm still trying to hone my cut and paste skills.

Thanks for the feedback on the size of the baffle and cabinet using the different mid drivers.

Lou

TRADERXFAN · « **Reply #12 on:** 14 Jun 2008, 04:58 pm »

found this on the 1 review (currently) on the small curved cabinet:

http://www.partsexpress.com/pe/showdetl.cfm?Partnumber=302-713&vReviewShow=1&vReviewRand=4320985#reviews

"Response from Parts Express:
On some of the curved sided cabinets there is a horizontal cross member centered in the front of the cabinet. This cross member may be removed to facilitate certain speaker configurations. Removing the cross member is easily done with a wall board saw.

Removing this cross member will not compromise the structural integrity of the enclosure.

Future shipments will have the cross member screwed-in (no sawing required) with a note to remove the screws."

But its probably better to leave it and cut it to keep it better braced.

Danny Richie · « **Reply #13 on:** 14 Jun 2008, 05:07 pm »

It might also serve them well to correct the false claims of the internal volume. I phoned them and brought it to their attention but the attitude I got from them was that they really didn't care.

Danny Richie · « **Reply #14 on:** 14 Jun 2008, 05:27 pm »

Anyone interested in building our A/V-1, Neo-1, Neo-1X, and Neo-2X kits using the PE cabinets please let me know. I am going to check into doing a group buy on them. It should save you guys a few bucks (about $50 a pair).

Here are the kits that can use them:

http://www.gr-research.com/index.asp?PageAction=VIEWPROD&ProdID=115

http://www.audiocircle.com/index.php?topic=54380.0

http://www.audiocircle.com/index.php?topic=54381.0

http://www.audiocircle.com/index.php?topic=54382.0

Here are the PE cabinets that can be used. Their part numbers for the smaller one are, 302-713, 302-717, and 302-711. My cost on these is about $69. each in quantities. That will save you guys about $25 a cabinet.

The larger cabinets are, 302-723, 302-727, and 302-721. These cost me about $74 in quantities. These will save you guys about $25 a cabinet.

Post here if you are interested.

Loftprojection · « **Reply #15 on:** 16 Jun 2008, 03:23 pm »

Hey Danny, just to sum things up, are these steps below all that we have to accomplish for a completed kit or is there something I'm missing?

- The two holes on the baffle are already the right size for the woofer and tweeter, you only need to cut a recess in order for the tweeter to be flush.

- There is a hole in the back that will accommodate the binding posts but you need to make the a bit larger with a drill bit.

- There is a hole in the back that will accommodate the port (for Neo-1x) so nothing to do there. Or is there no hole and it has to be cut?

- The interior brace needs to be cut in the middle.

- The cross-over parts have to be soldered and installed based on the schematic you will provide.

Thanks

Danny Richie · « **Reply #16 on:** 16 Jun 2008, 03:38 pm »

Quote

- The two holes on the baffle are already the right size for the woofer and tweeter, you only need to cut a recess in order for the tweeter to be flush.

Front baffles are blank. You have to cut the driver holes.

Quote

There is a hole in the back that will accommodate the binding posts but you need to make the a bit larger with a drill bit.

Correct.

Quote

There is a hole in the back that will accommodate the port (for Neo-1x) so nothing to do there. Or is there no hole and it has to be cut?

There are no holes in the back for a port. That must also be cut.

Quote

The cross-over parts have to be soldered and installed based on the schematic you will provide.

Correct.

laserman · « **Reply #17 on:** 16 Jun 2008, 10:28 pm »

Danny,

I'm interested but am wondering about the net internal volume issue. If the curved cabinets are close to the bottom value your drivers would operate optiminally, why wouldn't you recommend going with the rectanglur cabinet to give them more AIR ? LINK

If you get the cabinets will they ship from your location or from PE's location ?

I ready to pull the triger on these giant killers...

Lou

Danny Richie · « **Reply #18 on:** 16 Jun 2008, 10:39 pm »

Lou,

Those will work too.

If I do the group buy thing then it will have to be a deal where PE drop ships them to each person otherwise the two way shipping would eat up the savings.

Loftprojection · « **Reply #19 on:** 16 Jun 2008, 11:33 pm »

Ho, didn't realize there was no holes for the drivers and port. Since those are already finished, do you have a trick for cutting the holes without scratching the varnish/paint?