[Danny Richie]

Just tap over the surface with something frist. I usually use clear packing tape. Then when you are done just peal it off.

Or you could go for the good stuff and use the 3M Blue tape. 

[richt@daytonaudio.com]

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, in all due respect, I'd like to say that we do listen to our customers and contrary to your statement, we do care. Information regarding the internal volume measurements was passed along to the product engineers here at Dayton Audio and we discussed things this morning. At the bottom of this post you'll find the actual manufactured internal volumes of both the traditional and curve cabinet designs.  Additional comments follow:

All cabinets are slightly larger than advertised with the exception of .5 ft³ cabinets which are .494 ft³ for the traditional and .477 ft ³ for the curved sided. The traditional is 1.2% undersized and the curved sided is 4.6% undersized. Although the .5 ft³ curved sided is undersized (slightly) it is certainly in the ballpark and would not change any aspect (f3, Qtc etc.) of a box/speaker combination, therefore we feel it isn't necessary to change how we advertise them.

Due to the shape of the curved sided cabinets it is almost impossible to measure within ± 5% using a ruler. Accurate measurement would require geometry and or calculus, another method would be to fill the enclosure with some material (small beads, popcorn, sand, water), empty the contents into a basic shape enclosure and measure the amount

Finally, we are working on getting all Dayton cabinet drawings up on the website. The drawings indicate the box volume so this may help, but even with the detailed drawings it is difficult to derive internal volume of the curved sided cabinet.

Feel free to pass comments, suggestions, or questions directly to us here at Dayton Audio.  My email address is:  richtATSIGNdaytonaudio.com

As always, we thank you for your patronage! 

Rich Taylor
Brand Manager
Dayton Audio


MANUFACTURED DAYTON CABINET INTERNAL VOLUME   
   
TRADITIONAL   ft³   

0.25 TWO-WAY   0.281    
0.38 TWO-WAY   0.387    
0.5 TWO-WAY   0.494    
0.75 TWO-WAY    0.780    
0.75 MTM   0.763    
1.0 MTM                0.999    
1.0 SUB                1.084    
2.0 SUB                2.084    
3.0 SUB                3.122    
      
CURVED      
0.25 TWO-WAY   0.283    
0.38 TWO-WAY   0.392    
0.5 TWO-WAY   0.477    
0.75 TWO-WAY    0.788    
0.75 MTM   0.763    
1.0 MTM                1.010    
      
      

[Vapor Audio]

Parts Express vs GR ... I need some popcorn!

Just kidding, both are some of the best people in the business.  Hey Danny, how did you come up with your numbers?  I was going to ask before since I saw someone on another board saying they calculated the internal volume completely differently than you did and came up with numbers pretty close to spec.

Question for both sides, are you counting the volume of the internal bracing? 

If the Dayton cabs turn out to the correct volume as spec'd, that's good for everybody!

[laserman]

Hi Rich,

Nice cabinets you offer - both curved and traditional.  This helps me alot since I was fence sitting on which way to go due to the internal volume concerns I had.  It looks like this is a moot point now as long as the internal brace and crossover parts were included in calculations.  I believe that is why Danny has us cutting a portion of it out.

Okay, now that we have resolved the internal volume, and gotten the greetings out of the way, how about that internal brace ??  Can you do something about repositioning it so it goes front to back verses top to bottom ?  Regardless of how it runs, could you make it so it can be moved just in case it needed to be ??  The end user would be responsible to glue it into the desired final possition.

Thanks for stopping by to provide assistance.

All the best,
Lou

[Danny Richie]

Hey thanks for joining in and posting over here. I really appreciate it Rich.

Danny, in all due respect, I'd like to say that we do listen to our customers and contrary to your statement, we do care.

Excellent! The person that I spoke to on the phone didn't sound like they were too excited about it when I informed them of the problem.

And with all due respect. Your cabinet volumes on the curved cabinets are way off published specs.

All cabinets are slightly larger than advertised with the exception of .5 ft³ cabinets which are .494 ft³ for the traditional and .477 ft ³ for the curved sided.

You mean these cabinets?

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-720

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-721

Rich, you really think that you can take the back wall of a cabinet and reduce it from being 7" wide on the inside to 3.5" wide at the back and only loose .017 cubic feet? Grated it is 1/2" of an inch deeper but that won't give you back that much air space.

Lets look at this one: http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-720

External numbers are 14" by 8.5" by 12". The box is all 3/4" thick. So internally we have 12.5' by 7" by 10.25" (remember that the front baffle is 1" thick). Now the brace is 3/4" thick and about half of the material is removed. So if we take away .375" of depth for the brace then the depth is now 9.875"

Now do the math. 12.5 times 7 times 9.875 equals 864.0625. Now divide that by 1 cubic foot (1728 sq in.) and you get right at .5 cubic feet.

Good job. It is plus or minus pretty much right on the numbers.

Now this one is a little more complicated but still pretty easy: http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-721

You guys sell some software called Bass Box that makes it real easy too. You can drop in the numbers for odd shapes and it will really help you out.

Even by the posted measurements the height of the box (internally) is 12.5". Depth is 10.5" (keep in mind that the front baffle is 1" thick). Then subtract out the thickness of the brace minus its holes, which is about half of its volume, and it is a 3/4" thick brace. So now you have a depth of 10.125". The width at the rear is 3.5" The rear tapering reduces the cabinet width to thinner walls by the end of it. It is advertised as 4.5" wide externally, but since the walls get thinner in the rear it is 3.5" wide on the inside and not 3" wide as one would think. Then you have a width at the front of 7" across the front. That is .377 cubic feet by the numbers.

Granted the sides have a slight curve and are not a straight line from the front to the back but it won't give back much.

Even if you took the width at the front and the width at the back and averaged it you'd get 5.25" of width. With that width and the same height and depth you get .385 cubic feet.

Let's say that it has the same height and depth but no taper at all. It is the same width all the way down the length of the box. 12.5" tall, 10.125" deep and 7" wide. That would make it .513 cubic feet if it weren't even tapered at all. (W x H x D and divide by 1728). Are you still sure about those numbers?

I think you guys at PE need to not just take the word of the company that builds them for you. You really should go measure these yourself. These are a long way from published specs.

Due to the shape of the curved sided cabinets it is almost impossible to measure within ± 5% using a ruler.

Actually it is pretty easy to measure with a measuring tape. Even if I were off by as much as 5% to the large size that would still only make the .5 cubic foot curved box only .396 cubic feet.

Please feel free to continue to post here.

[richt@daytonaudio.com]

Danny,

Thank you for your response and passion but I must correct some of your dimensions and a basic flaw in some of your assumptions.

First and foremost, please keep in mind we are dealing with a total internal volume that is right of the decimal (less than 1). Any and all measurement deviations no matter how minor they may look on the surface can make a significant difference. 

1. The cabinet walls are made using 18mm (.7087) thick MDF not 3/4” (.750). It is common when converting from metric to inches
2. The vertical internal brace is made of 15mm (.5906) thick MDF not ¾” (.750)
3. Your assumption regarding the total volume displaced by the internal brace is suspect at best. To say “subtract out the thickness of the brace minus its holes, which is ABOUT HALF OF ITS VOLUME” is not an accurate enough method of measurement..
4. The walls of the cabinet do not get “thinner” toward the rear. The walls maintain the same 18mm thickness from front to rear.
5. The curve cabinet is not a “Trapezoidal” shape with the sides being straight. The sides actually bow outward before they gradually curve in toward the rear. The width of the cabinet is 8.5” at the baffle, the maximum width of the cabinet is 8.65”. This may seem minor, but again all of these “minor” issues are starting to add up!
6. If you are relying on Bass Box to help calculate this may be part of the problem! The shape of this cabinet is far too complex for Bass Box to calculate correctly.

Also listed below is a link to another forum from a gentleman that has read your post and measured the cabinets using simple geometry. His numbers are coming out close to ours.

http://www.htguide.com/forum/showthread.php4?t=30443


Summary,
Our factory is one of the best cabinet factories in the world. They have over 30 design engineers on staff using the latest CAD systems that can accurately calculate internal volume and we stand by our measurements.


Thanks again,

Rich Taylor
Brand Manager
Dayton Audio

[KS]

Try it the simple minded way...Fill the enclosure with sand, then pour the sand out and measure the volume of sand. 

1 cubic foot = 7.48 (liquid) gallons, which is the measure to use with an empty paint pail, etc.
0.5 cubic foot = 3.74 gallons;  or, 3 gallons plus 11.8 measuring cups.

By the way, does No-Rez or other damping products materially reduce the internal volume in an acoustic sense?  Or do the cabinet dimensions assume the inclusion of damping material.

[Danny Richie]

Thank you for your response and passion but I must correct some of your dimensions and a basic flaw in some of your assumptions.

Okay, I'll play along. Let's see.

First and foremost, please keep in mind we are dealing with a total internal volume that is right of the decimal (less than 1).

Oh really? I guess that is not too significant. Lets look at it another way. I'll be overly generous and say your .5 cubic foot curved sides box is .4 cubic feet rather than what I stated before. That is a 20% deviation if it is less than .1 cubic feet in difference. That seems fairly significant to me.

First off, I will confess I did make an error in what I stated above. When I stated the depth of the box, I stated it as 10.125" taking into account the thickness of the brace as if half of it were gone. It should have been 10.375". That would actually make it .387 cubic feet of air space and not .377 cubic feet.

So we are at .387 cubic feet based on the posted data on your web site and taking into account some deviation in thickness near the rear of the box. 

1. The cabinet walls are made using 18mm (.7087) thick MDF not 3/4” (.750). It is common when converting from metric to inches

Okay then, the internals increase to 12.6" high by 7.1" wide at the front and by 3.6" wide in the back by 10.425" deep. Thank you for that correction. You are now up to .399 cubic feet.

2. The vertical internal brace is made of 15mm (.5906) thick MDF not ¾” (.750)

Okay, that is a difference of 3mm total. I allowed for half of that thickness to actually take up air space. So I would need to give back 1.5mm to the depth. That is .05905512 inches. Now we are up to .400 cubic feet.

3. Your assumption regarding the total volume displaced by the internal brace is suspect at best. To say “subtract out the thickness of the brace minus its holes, which is ABOUT HALF OF ITS VOLUME” is not an accurate enough method of measurement..

  I'll go one further than that and say that it isn't even there to begin with. That would crank it up to .414 cubic feet. We are still a long way from .5 cubic feet.

4. The walls of the cabinet do not get “thinner” toward the rear. The walls maintain the same 18mm thickness from front to rear.

Well, I measured right at 3.5" wide on the inside at the back wall. The 2" flared port from PSP is 3.97" wide on the inside and I placed it in the back of the cabinet on four of the ones that I ordered. I'd say it took out about a .25" of the side wall at the back on each side as it went through. That would also tend to confirm the 3.5" thickness on the inside. But if you insist, that makes it 3.1" on the inside. Now you are back to .377 cubic feet. That is still considering that the brace takes up half of the air space of its thickness. 

5. The curve cabinet is not a “Trapezoidal” shape with the sides being straight. The sides actually bow outward before they gradually curve in toward the rear. The width of the cabinet is 8.5” at the baffle, the maximum width of the cabinet is 8.65”. This may seem minor, but again all of these “minor” issues are starting to add up!

Yep. I mentioned that. It will add a little, but not much. Deducting the entire thickness of the brace as if there was no brace there at all gives back more than that will. I'll add that back again. You are up to .380 cubic feet. We are still a long way from .5 cubic feet.

6. If you are relying on Bass Box to help calculate this may be part of the problem! The shape of this cabinet is far too complex for Bass Box to calculate correctly.

Come on now Rich. This is a simple truncated pyramid with a little curve to the sides.

Also listed below is a link to another forum from a gentleman that has read your post and measured the cabinets using simple geometry. His numbers are coming out close to ours. http://www.htguide.com/forum/showthread.php4?t=30443

That's it Rich? You found a hobbyist whose numbers came closer to yours? Come on Rich. Go measure the boxes yourself and you'll see.

Let's do this: Let's throw all this technical stuff out the window and let's say we don't know too much about math. We can only measure straight boxes. Let's just use a little common sense shall we?

These two boxes that you offer have the same size front baffle and are made to the same thickness. Right?

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-720

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=302-721

By the numbers the one with the straight walls comes up right at .5 cubic feet, and trust me, that one is real easy to measure. You claim it to only be .494 cubic feet. Great! That is plenty close enough.

Your engineers at the factory that happens to be "one of the best cabinet factories in the world" states that the difference in internal volume between the two boxes is only .017 cubic feet.

The curved one is .5" deeper (which would add .018 cubic feet on the curved box over the straight one, by the way), however the rear baffle gets 4" smaller on the inside compared to the front baffle (7.1" to 3.1") and is a significant difference.

And it only lost .017 total cubic feet? Really? REALLY?

It lost 4" on the back wall over a 12.5" tall area and only lost .017 cubic feet?

That would be the same as taking the straight sides box that is .5 cubic feet and shortening the depth by .335". So shortening the depth of that box by .335" (that is less than 3/8 of an inch) gives you the same air space as adding .5" of depth and reducing the rear wall width by 4"? Are you kidding me?

If you took the box with the straight sides and moved one side wall in by .25" it would reduce the internal volume by .018 cubic feet.

Come on! I am really trying to help you out here.

Our factory is one of the best cabinet factories in the world. They have over 30 design engineers on staff using the latest CAD systems that can accurately calculate internal volume and we stand by our measurements.

Considering how well these front baffles fit on the rest of the box (or didn't fit), and the variance in the amount of overhang around the sides, I have a tough time going along with the "best cabinet factory in the world".

What I do think is that these are pretty nice cabinets and very nice for the money. I like them well enough to recommend them (with a minor modification) to my customers to use in 4 different kits that I offer. I am driving sales your way. Nice boxes, but the published air space value is not correct. ALL of the published air spaces on ALL of your curved boxes are not correct.

So, how about taking some measurements on those boxes yourself and getting back to us?

[Danny Richie]

By the way, does No-Rez or other damping products materially reduce the internal volume in an acoustic sense?  Or do the cabinet dimensions assume the inclusion of damping material.

The numbers that we have been kicking around does not include allowances for damping material.

The thick damping layer of the No Rez does take up air space, but the foam layer slows down air flow in the box and gives it back. It is typically about a wash and it has little effect on the overall volume.

[Kevin Haskins]

I agree with Danny, the boxes are smaller than advertised.   

I think they are nice cabinets, you just need to adjust for the volume so people have a better idea of what they are actually getting.    Also keep in mind that drivers, ports and crossovers eat up a lot more volume proportionally when you are working with these small cabinets.   You probably should rate them 5-10% oversize so that DIYers get closer to their actual targets.    It wouldn't be a bad idea to aim for 0.55 cubic feet and call it 0.5 cubic feet.    You will get DIYers closer to their targets and give yourself a little wiggle room in the construction process.

[Zero the Hero]

common sense would dictate that the box that is 4" narrower but only .5 deeper would be considerably less volume, but why doesn't someone just pour some sand and measure them?

[dsrviola]

but why doesn't someone just pour some sand and measure them?

Amen!!!

[Hank]

I'll second that A-men.  That should prove to PE that they need to either change the published box volume, or replace that series with one that actually does have .5 ft^3 volume.

[laserman]

I telephoned Rich Taylor @ Dayton Audio and he apparently referred this thread and my name to PE.  A PE representative telephoned me today and was extremely nice.  He stated they are going to look into this and provide a response by the end of the week.  The response will be to make sure the advertised cubic feet is as stated and to verify the measurement of the curved cabinet.  He was apologetic for the confusion this has had on end users and stated he will try very hard to have a resolution on this and provide an answer by Friday.   

[pecker]

Hi Rich,

Nice cabinets you offer - both curved and traditional.  This helps me alot since I was fence sitting on which way to go due to the internal volume concerns I had.  It looks like this is a moot point now as long as the internal brace and crossover parts were included in calculations.  I believe that is why Danny has us cutting a portion of it out.

Okay, now that we have resolved the internal volume, and gotten the greetings out of the way, how about that internal brace ??  Can you do something about repositioning it so it goes front to back verses top to bottom ?  Regardless of how it runs, could you make it so it can be moved just in case it needed to be ??  The end user would be responsible to glue it into the desired final possition.

Thanks for stopping by to provide assistance.

All the best,
Lou

I made some homebrew curved cabinets using kerf cuts, rather than the laminated ply or mdf that PE used. Even after filling the kerfs with fiberglass resin and applying damping sheets inside, they had a rather obvious resonance.

I found these inexpensive turnbuckles to use. Put a bit of "GOOP" type adhesive on the threads, and tighten them. You can actually tune the resonance to whatever you prefer by increasing the tension and varying their placement. Add a bit of GOOP on the ends when your satisfied, and they should never vibrate loose.

[Danny Richie]

I was really hoping to have heard back from Parts Express on this deal last week, but did not.

Hey Parts Express, Rich Taylor, or whoever is in charge. I'd really like to see these boxes made a little deeper to actually provide the advertised volumes as I can really use a lot of them and I can direct a lot of my customers that direction for cabinets.

[laserman]

Drum roll please
 

Okay, after a couple more telephone calls to PE, I finally got a representative to physically measure the regular (302-726) and curved (302-727) .5 ft³ cabinets.  The regular one measured as advertised on PE’s website.  The curved one measured larger and here is what the representative stated:

14.1” (H) x 13.5” (D)(w/baffle attached) X 8.9 – 5.0” (W)

So, taking what Rich Taylor stated above about the thickness of the sidewalls and ½ off the thickness of the front baffle, one gets these internal measurements:

12.1” (H) x 11.5” (D) x 7.4-3.5” (W)

Okay, assuming Rich’s brace figure (reducing the Depth by half the brace thichness to a new total of 11.2”), and taking the average of the Width [ (.617 +.292) /2 = .455 ], I arrived at this ft³  total:

1.05 x .933 x .455 = .45 ft³  
 
If this is indeed the new corrected measurements, then this is much closer to the .5 ft³ advertised.  The representative stated they had a couple meeting about this very topic and will be correcting the published measurements in their flyer and website.

I hope this helps the next person out…I couldn’t wait and ordered the regular cabinet last week to play it safe. 

[Danny Richie]

I just called and spoke with Skip as well (same guy laserman spoke with).

His measurement of 8.9 at the width was at its widest point not at the front baffle. But he told me it was 8.78".

He seems to think that because of the issue with them being off on the measured air space that the new ones are now an inch deeper.

I asked him if there was any way I could know when I ordered if I would be getting the new ones that are an inch deeper or the older ones that were only 12.5" deep and he said all of the older ones are now gone and all of the cabinets in stock now are 13.5" deep.

He thought that they might have done the same with the smaller boxes as well but was not sure. I am supposed to call him back on Saturday to see as he will be pulling a bunch of them and measuring actual volume on each of them.

If what he said was true, (and I am sure that it is), and the information about the actual wall thickness mentioned by Rich is true, (and an am sure that it is), then this added inch of depth should bump the volume of the .5 cubic feet box up to .438 cubic feet. It's still not .5 cubic feet but it is getting closer. That makes it only 13% off instead of 20% off.

He also stated that they would be restating the volume to what it actual measures.

I wonder if we can talk them into adding yet another 1.5" of depth? That would get them up to .495 cubic feet.

[KS]

If you'll be a big enough customer, can you ask for the enclosures to be sized in liters as well as cubic feet?  That might make more sense to their supplier (Chinese or other offshore manufacturer?).

13 liters = .46 cu. ft.
14 liters = .49 cu. ft.
15 liters = .53 cu. ft.
16 liters = .57 cu. ft.

Would you like to get more than .5 cubic feet in the empty box to allow for the volume of the crossover network, back side of the drivers, etc?

[Danny Richie]

Would you like to get more than .5 cubic feet in the empty box to allow for the volume of the crossover network, back side of the drivers, etc?

Sure, for our Neo-2X kit it would be ideal.