Toolfan, I just need to know, why so against plywood?
Not the basic hardware store stuff, we are talking Baltic birch here.
I made a lot of speakers out of Baltic birch, great to work with. The only thing I would use MDF for is table tops and subs. Don't care for the stuff.
Polk S10, S8, S4
Polk RT8
Polk Monitor 7s
Working on getting SDAs
So I'm starting to do preliminary design work on the cabinet. Polk specifications have the exterior dimensions as 28"x16"x11.5" I'm using a 3/4" wall thickness and 1" back and front. I may need to stretch the 11.5" depth to 12.5" since I'm pretty sure Monitor 10's were 3/4" wall thickness all the way around.
If one of your has a 10 cabinet you can measure interior dimension exactly, I will duplicate volume. I'm not sure if I will have to compensate for the volume lost on filling the corners?
Here is the complete unit. I'm showing the back side of the front. I plan on rounding the inside ports.
Again I don't have the exact locations of the PR, driver and Woofers. If someone can measure theirs I can make changes.
The front and back are MDF 1" construction. Both the front and back exterior will be laminated with matt black poly textured sheets. Walls are 3/4" walnut laminated.
I'm not sure if I need to consider having the corners between the front face and sides rounded. Still contemplating.
Any help you can give on actual measurements would be great be great.
I built a pair of Full range crossover less speakers using a kit from Madisounds that uses Baltic birch plywood and I think they sound pretty good for what they are...
Thanks for sharing. I have seen many of these kits and they look like an interesting project.
The more research I do, the more I discover MDF will produce the best results for the cost. I have seen very pricey solid wood speakers but I'm sure the manufactorer takes that consideration.
I was originally going to make the cabinets from solid wood but that could have been a disaster
To put it simply, as someone did for me, wood can be made into an instrument like a note on the marimba. You can't do that with MDF. You can with baltic plywood, it won't sound pretty but it will resonate.
I'm building a clone vintage Monitor and I'm even now concerned with using MDF rather than the original particleboard. I'm hoping there will be an improvement or at least little difference.
Keep in mind, partial board is more dense than wood, (more mass per volume) but not rigid, poor strength, and as you stated, degradates especially in water. Partial board is the least dense of the manufactured wood products according to Wikipedia which makes since.
Not going to give it up are you. I will concur, the M10 design has its issues, but I like its strengths as crude as some may think.
This was suggested by another forum. The rational is a driver moves air. Rounding the inside promotes that movement, especially since I'm increasing the thickness of the front panel. I can't see how it would hurt.
Na, slightly weaker. From an engineering point of view, and I am an engineer, the material removed offers little structural support to the mounting of the driver. It can hurt the space between the drivers but drawing that takes more than a few minutes so I didn't show that. I don't plan on routing out the material between the drivers, just hand rounding,.
So if that is what you meant, good catch.
I'm more concerned about to total lack of cross sectional area horizontally through the drivers but since the front panel is affixed to the casing, maybe a corner block in that area wouldn't hurt.
Non issue, possibly for these drivers in a sealed cabinet system. It was suggested for "ported" (the proper term escapes now) system where the amplitude of the driver or woofer is much greater. (Once I start using the proper terms, I'll start remember them)
I like the rounding of the corners, just not the holes for the driver mount. This is a non-issue and can only be detrimental as you are essentially making the mounting area weaker by having less bulk where it needs it most.
Agreed.
Political Correctness'.........defined
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
I think he's referring to rounding the cabinet's inside edges to smooth out the air flow as I read that in the link he provided earlier that included box design [ btw Thanks for that it was a good read] Just curious on this topic -would it be at all detrimental to use a thin veneer on the front face to provide a all wood look?
Yes! That's what I mean.
I'm not a fan of that look but it would be interesting with a contrasting wood color. Walnut cabinet and chamfer with a maple face? (with figure)
Question. If I rearrange the components like a 7 starting at the top working down, driver, tweeter, driver, PS, narrow the width to M7's width, keep the depth, but adjust the height of the case to match volume of a M10, wouldn't the design resonance stay the same.
Of course many bad things could happen but what do you know will happen?
I actually like that idea. You could do an MTM arrangement, and either reverse the phase of the Tweeter, or offset it 45 degrees from the centerline of the two woofers to mitigate lobing. the offset version should be made in mirror images.
These all fall under the category of Franken-Polks of course.
The ideas are looking good, let's see some wood getting cut..
This weekend! I'm so looking forward to it! Still looking for 1" MDF locally, the right veneer and contact cement, and waiting for my RD0-194 tweeters.
I actually like that idea. You could do an MTM arrangement, and either reverse the phase of the Tweeter, or offset it 45 degrees from the centerline of the two woofers to mitigate lobing. the offset version should be made in mirror images.
These all fall under the category of Franken-Polks of course.
How would that effect the PR's performance with drivers not equal distance or is that not an issue?
The ideas are looking good, let's see some wood getting cut..
This weekend! I'm so looking forward to it! Still looking for 1" MDF locally, the right veneer and contact cement, and waiting for my RD0-194 tweeters.
I actually like that idea. You could do an MTM arrangement, and either reverse the phase of the Tweeter, or offset it 45 degrees from the centerline of the two woofers to mitigate lobing. the offset version should be made in mirror images.
These all fall under the category of Franken-Polks of course.
How would that effect the PR's performance with drivers not equal distance or is that not an issue?
It's called fluid coupling, air being the fluid. No difference as long as the internal volume is the same.
Comments
Toolfan, I just need to know, why so against plywood?
Not the basic hardware store stuff, we are talking Baltic birch here.
I made a lot of speakers out of Baltic birch, great to work with. The only thing I would use MDF for is table tops and subs. Don't care for the stuff.
Polk RT8
Polk Monitor 7s
Working on getting SDAs
If one of your has a 10 cabinet you can measure interior dimension exactly, I will duplicate volume. I'm not sure if I will have to compensate for the volume lost on filling the corners?
Your thoughts?
Again I don't have the exact locations of the PR, driver and Woofers. If someone can measure theirs I can make changes.
The front and back are MDF 1" construction. Both the front and back exterior will be laminated with matt black poly textured sheets. Walls are 3/4" walnut laminated.
I'm not sure if I need to consider having the corners between the front face and sides rounded. Still contemplating.
Any help you can give on actual measurements would be great be great.
HT - Polk 703's * NAD T-758 * Adcom 5503 * Oppo 103 * Samsung 60" series 8 LCD
and BTW
here is a pair of Stirling Broadcast LS35a that uses 9mm birch plywood
http://store.acousticsounds.com/d/88073/Stirling_Broadcast-LS35a_V2_Speakers-Speakers
HT - Polk 703's * NAD T-758 * Adcom 5503 * Oppo 103 * Samsung 60" series 8 LCD
The more research I do, the more I discover MDF will produce the best results for the cost. I have seen very pricey solid wood speakers but I'm sure the manufactorer takes that consideration.
I was originally going to make the cabinets from solid wood but that could have been a disaster
To put it simply, as someone did for me, wood can be made into an instrument like a note on the marimba. You can't do that with MDF. You can with baltic plywood, it won't sound pretty but it will resonate.
I'm building a clone vintage Monitor and I'm even now concerned with using MDF rather than the original particleboard. I'm hoping there will be an improvement or at least little difference.
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
Cables: Speaker: Furez 10/2 with GLS Locking Banana Plugs
Interconnect: Furez 10/2 with SpeakONs
ICs: Custom Furez by Douglas Connections
Den:
Bose 901 Series II Continentals Restored, Re-Built Equalizer with Elna Silmic IIs, Sonicaps, and Silver Mica Caps
Carver CT-3 Pre, Carver C-500
dhsspeakerservice.com/
Exclusive Distributor of Gimpod's Custom SDA Circuit Boards
"And keep her under 70, would you, huh? Betty likes a slow ride"
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
Cables: Speaker: Furez 10/2 with GLS Locking Banana Plugs
Interconnect: Furez 10/2 with SpeakONs
ICs: Custom Furez by Douglas Connections
Den:
Bose 901 Series II Continentals Restored, Re-Built Equalizer with Elna Silmic IIs, Sonicaps, and Silver Mica Caps
Carver CT-3 Pre, Carver C-500
dhsspeakerservice.com/
Exclusive Distributor of Gimpod's Custom SDA Circuit Boards
"And keep her under 70, would you, huh? Betty likes a slow ride"
This was suggested by another forum. The rational is a driver moves air. Rounding the inside promotes that movement, especially since I'm increasing the thickness of the front panel. I can't see how it would hurt.
So if that is what you meant, good catch.
That is great help!
I plan on plotting it 1 to 1 and confirming with the actual components.
Thanks again.
Agreed.
"A doctrine fostered by a delusional, illogical minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a t-u-r-d by the clean end."
President of Club Polk
Yes! That's what I mean.
I'm not a fan of that look but it would be interesting with a contrasting wood color. Walnut cabinet and chamfer with a maple face? (with figure)
Of course many bad things could happen but what do you know will happen?
These all fall under the category of Franken-Polks of course.
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
Cables: Speaker: Furez 10/2 with GLS Locking Banana Plugs
Interconnect: Furez 10/2 with SpeakONs
ICs: Custom Furez by Douglas Connections
Den:
Bose 901 Series II Continentals Restored, Re-Built Equalizer with Elna Silmic IIs, Sonicaps, and Silver Mica Caps
Carver CT-3 Pre, Carver C-500
dhsspeakerservice.com/
Exclusive Distributor of Gimpod's Custom SDA Circuit Boards
"And keep her under 70, would you, huh? Betty likes a slow ride"
This weekend! I'm so looking forward to it! Still looking for 1" MDF locally, the right veneer and contact cement, and waiting for my RD0-194 tweeters.
How would that effect the PR's performance with drivers not equal distance or is that not an issue?
Your drivers shipped out today..
Front: SDA-2ATL forum.polkaudio.com/discussion/143984/my-2as-finally-finished-almost/p1
Center: Custom Built forum.polkaudio.com/discussion/150760/my-center-channel-project/p1
Surrounds & Rears: Custom Built forum.polkaudio.com/discussion/151647/my-surround-project/p1
Sonicaps, Mills, RDO-194s-198s, Dynamat, Hurricane Nuts, Blackhole5
Pioneer Elite VSX-72TXV, Carver PM-600, SVS PB2-Plus Subwoofer
Cables: Speaker: Furez 10/2 with GLS Locking Banana Plugs
Interconnect: Furez 10/2 with SpeakONs
ICs: Custom Furez by Douglas Connections
Den:
Bose 901 Series II Continentals Restored, Re-Built Equalizer with Elna Silmic IIs, Sonicaps, and Silver Mica Caps
Carver CT-3 Pre, Carver C-500
dhsspeakerservice.com/
Exclusive Distributor of Gimpod's Custom SDA Circuit Boards
"And keep her under 70, would you, huh? Betty likes a slow ride"