Gottcha, I may skip the filling of the corners. That gets off the original plan of making a clone and adding gusseting just creates another question. Then the solution to the volume change sets up another question, which axis do you add the volume, or is it all three?
I'm pre-fitting the components in my crossovers. I'm planning on using 3M foam tape to secure the caps, both top and bottom on the first tier.
Instead of using a disc of press board, I'm going to use scrap polk driver boards and 1 1/4" steel risers that will fit in the originals.
I also re-purposed some clear sticky tape from polk drivers to wrap the large inductors. My old eBay drivers only had a dab of hot glue to secure the coils. I didn't do the job.
The profile picture is from the day I acquired my SDA 2 speakers which are standing proud in my listening area...and can shock and amaze people with the imaging, especially when friends learn the whole HT was off but for those two bad boys.
I have never heard a pair but always keep my open for a pair of SDA'S fixer-uppers... Very sweet!
Looks like you have your work cut out for you. Would love to hear them.
Here is a layman's article on the effect of steel near the inductors. I think I would be far more concerned with the driver/tweeter magnets in the vicinity of the inductors. It looks like the crossover is placed very close to the magnets in the original M10 design. Something to keep in mind.
Effect of magnetic fields are inversely proportional to distance cubed, so you don't have to get too far away to make the effects inconsequential. It would be an interesting test to compare inductance with nylon risers or with steel risers, including the screws. And with the driver in speaker then out. The steel in the cap leads could also be considered.
May make a good case to relocate the inductors someplace else.
I wonder if polk tested speakers in real world application or just followed the theoretical.
If it helps I took some measurements of my 10a's with the speakers still installed,They're in [cm] for easier reading- The BLACK face board is 36.4x67cm, giving a vertical center line of 18,2 for the tweeter and PR [Note: the measurements are taken from the face board edges [not the outside cabinet edges]-the [tweeter] -from board top edge down is 9.3 to top of tweeter and to the bottom of tweeter edge is 17 -from the board [side] edge is 12.3// The [spk mids] are 1.5 from board [side] edge to the outside spk edge and 18.1 to the inside. Then again measured from the board [top] edge down are 17.4 to top of spk and 34 to spk's bottom edge [26 from board [top] down to the spk horizontal center line]// The PR is 5.6 measured from the board bottom up to the PR's bottom and 31.1 to the top and 5.5 to the board [side] and with a horizontal center of about 18.5. The tweeter used is a peerless and the measurements should be within 1.5 mm accurate,Maybe you can lay it out on some graph paper to check and make a template with your drivers altering the measurements to adjust for their flange edges,,,BTW the outside dimensions of the finished box are- [ 40.4x71.1x11cm deep ] the cabinet board thickness is 1,5cm
rmpolk took some time and posted measurements he took from his pair of M10's.
Below are two drawings, the first in cm and the second in inches. These may not be exact but it gets me very close to the original placement of the components.
Thank rmpolk for posting. I will be using your measurements as the basis of my clones.
As far as aesthetics, the only obvious change is I may laminate the front with an Oak laminate rather than the satin black polk used. We'll have to see how that looks before making any permanent decisions...
Now that is a good question. The only answer I can give is I have seen M10's with painted fronts and others with what appears to be a poly laminate. Did polk test all construction materials including vendor changes and process improvements or did they say that's close enough, we're making money?
I am making my cabinet from MDF, not particle board, and I'm making 1" front and back panels rather than 3/4", so I think in my build it's moot.
If polk had a sonic benefit in mind using a laminate rather than something else, i would be impressed.
Stick with nylon risers...the steel will mess with the inductors on the terminal cups.
nbrowser - as you can see I went with the nylon standoffs for the additional riser, but I did use the original steel standoff on the first riser. So I haven't added any additional steel but I also haven't removed any. That meets my build criteria, right or wrong.
Comments
Thanks again for measuring. I'm adding 1/2" since I'm using 1" MDF front and back to keep the same volume.
I haven't decided if I'm going to compensate for the decreased volume by rounding all the interior corners.
I also haven't decided if I'm rounding the corners or use a 45 degree gusset? Round takes a router/shaper bit that I don't own.
Arrrg!
Instead of using a disc of press board, I'm going to use scrap polk driver boards and 1 1/4" steel risers that will fit in the originals.
I also re-purposed some clear sticky tape from polk drivers to wrap the large inductors. My old eBay drivers only had a dab of hot glue to secure the coils. I didn't do the job.
What's next?
I have never heard a pair but always keep my open for a pair of SDA'S fixer-uppers... Very sweet!
Here is a layman's article on the effect of steel near the inductors. I think I would be far more concerned with the driver/tweeter magnets in the vicinity of the inductors. It looks like the crossover is placed very close to the magnets in the original M10 design. Something to keep in mind.
Effect of magnetic fields are inversely proportional to distance cubed, so you don't have to get too far away to make the effects inconsequential. It would be an interesting test to compare inductance with nylon risers or with steel risers, including the screws. And with the driver in speaker then out. The steel in the cap leads could also be considered.
May make a good case to relocate the inductors someplace else.
I wonder if polk tested speakers in real world application or just followed the theoretical.
Far more than what I want to get into.
https://rennieash.wordpress.com/2013/02/08/the-effect-of-iron-on-inductance-value/
rmpolk took some time and posted measurements he took from his pair of M10's.
Below are two drawings, the first in cm and the second in inches. These may not be exact but it gets me very close to the original placement of the components.
Thank rmpolk for posting. I will be using your measurements as the basis of my clones.
I am making my cabinet from MDF, not particle board, and I'm making 1" front and back panels rather than 3/4", so I think in my build it's moot.
If polk had a sonic benefit in mind using a laminate rather than something else, i would be impressed.
nbrowser - as you can see I went with the nylon standoffs for the additional riser, but I did use the original steel standoff on the first riser. So I haven't added any additional steel but I also haven't removed any. That meets my build criteria, right or wrong.
Polk RT8
Polk Monitor 7s
Working on getting SDAs
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
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