Must try MOD - Foam inside the stamped steel baskets - YES!
Options
Comments
-
The magnet and surrounding area is much larger than the outer basket with the 4 holes. Foam helps, but there is a lot or room for improvement left on the table.
-
^^When the magnet assembly and dust cap has been removed, a spud can be used to pull the voice coil up just out of the way and you can add some foam to that recessed area, attached with power grab or the like. Rob @xschop did it and released one into the wild, never to report back home *sniff* lol.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
That’s why I said imagine.
It would be designed as a 6.5” mid woofer for a Polk Monitor 5, 7 or 10, for example.
I've been eyeing a 6.5" cast basket with spider reliefs (only insert foam here) and open spokes. The factory base plate would simply have to be tapped for it's 60mm PCD and the flange OD turned down (6.650") to drop right in a Monitor cabinet...
Don't take experimental gene therapies from known eugenicists. -
Very cool find! It looks like the basket depth is 15.5 + 35.5 mm = 51mm = 2.008" vs (hard to measure) around 1.65" on the Polk basket, based upon my 1983 MW6500 which I just eyeballed. Surround diameter is 158mm = 6.22" and I roughly measure 6.1" on my Polk which is not super far off.
Could be a problem unless the voice coil were reset?
I didn't check the relevant spider dimensions yet.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
On my donor basket (sent from @MrGeology) I got 1.65" also. The 26mm Dia. replacement coils are a little longer than factory ones anyway (35-40mm long), which will make up for the extra depth. Provides more coil cooling too with the open spider design.
You could drop in either a 4" (Polk) to 4.5" Dia. spider and fix that worn/sag issue (6500,6503,6510,6511)
Just need to hunt down a pre-assembled 6.5 paper recone kit and save a bunch of time.Don't take experimental gene therapies from known eugenicists. -
The 35.5mm = 1.398" isn't that far off from what I measure on my Polk MW6500 for the surround mount to the spider mount surface of 1.334". Could just use a 1/16" spacer if you even needed to do anything at all.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
I've got 36mm on this one. Then again, this is the thin gauge one I dissected.Don't take experimental gene therapies from known eugenicists.
-
This is very interesting…..
-
The soul of a Monitor 7.
Excerpt from the Polk brochure.
-
Great find. Good marketing blurb. I ate that stuff up when I was younger. The Bose marketing verbiage was great of that vintage, too.
I try to remind myself (especially when talking to grandparents about the good ol' days, or with people under 30 about why James Bond was such a sleaze): Consider all things in the context of their time and place.
Those midwoofers? They were so superior to Bose it was no comparison, but Bose marketing won me over in High School.
I have no doubt this design rang less than the majority of its market contemporaries (and other consumer designs of years' past them). But, as time goes on, and equipment improves, you look back on that state-of-the-art, say... 1989 Super Coupe or 1991 3000GT VR-4... and they could use some updates
I enjoy my 6xxx-equipped models every day. But I wouldn't if Polk hadn't worked to bring the level of sound value down to the price they did.
I'd still like to see a no-holds-barred new Monitor 7, even though they missed the 50th anniversary of the company boat.
When did the 7 hit the market? Maybe the 50th of the speaker that defined the company? Did it hit in 74?
The Thrifty Setups in Mah House Big thrifty stereo in the basement w/ my custom SDA-1C (built with help from kind forum members) * Beautiful 1966 MCM GE console upgraded w/ Bluetooth, Dual turntable, and Paradigm speakers in family room * Swanky 1980 Realistic system and great TEAC eq with dancing colored lights in the living room * custom 5B on a system for my Dad * Ye Olde college stereo in the garage -
plastic_avatar wrote: »Great find. Good marketing blurb. I ate that stuff up when I was younger. The Bose marketing verbiage was great of that vintage, too.
....
I'd still like to see a no-holds-barred new Monitor 7, even though they missed the 50th anniversary of the company boat.
When did the 7 hit the market? Maybe the 50th of the speaker that defined the company? Did it hit in 74?
It would be awesome if they did an updated modern but still retro appealing version.
They were trying to sell a very early version of the 7 when they were in the Gallagher Mansion, in late 1973. I have yet to see one of them on eBay and I wonder how many (if any) they actually sold.
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
They'd come with the new certified 3x3" BH5
Don't take experimental gene therapies from known eugenicists. -
The new 3 x 3 standard is very economical for today's times.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Shrinkflation is real.
In other news, did a test run. I took a 3/8" wide wood chisel to an MW that had a torn surround and badly creased cone. About every 1/4 turn of the perimeter I put a drop of WD-40 on the chisel ramp. The old surround came off clean without tearing. At this point I can either re-cone (thinking Carbon Fiber) and keep the factory basket, or move forward and cut the spider carefully and order the cast baskets. Still haven't found a 6.5" paper re-cone kit with the spider and voice coil attached.Don't take experimental gene therapies from known eugenicists. -
Using the original proprietary built cone, spider, surround and magnet assy is the way to go, or it's no longer a Polk speaker, IMO.
-
I agree, but where to find a copy of the paper cone is the mystery. The surround I have all dimensions for, even it's rollover thickness.Don't take experimental gene therapies from known eugenicists.
-
Only way is to use a donor MW6500.
-
And to make the magnet/pole-piece removable would be gold.Don't take experimental gene therapies from known eugenicists.
-
Maybe jig the magnet assy and basket by the surround. Remove the metal between them, back filling it in with 3-4 metal rods to get the support for the magnet assy back.
You would end up with a minimal area to reflect sound.
Just an idea to maintain the “Polk” integrity. -
The magnet and surrounding area is much larger than the outer basket with the 4 holes. Foam helps, but there is a lot or room for improvement left on the table.
I got my question answered regarding whether or not CSD would be a way to measure this and it turns out it just might be. Unfortunately CLIO isn't in my budget in the near future:
https://www.parts-express.com/Audiomatica-CLIO-Pocket-Version-2-Personal-Acoustic-Measurement-System-390-900?quantity=1
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
While shopping for tires (daughter’s Corolla) I saw this thinking “I MUST post this for George et al:”Interesting…
One of the higher-end tire manufacturers, attempting to attenuate ~200hz road noise using a similar execution of foam on the interior
“… 9dB - that is how much our ContiSilent™ can reduce the sound of road noise inside your car. An inner tyre absorber, made of polyurethane foam, is attached to the inner surface of the tyre tread, to cushion the road.” Different material and frequency range target but answers Hansvelton’s question. As I said elsewhere: Foaming my LC*Rs’ mids significantly reduced their upper midrange “bark.”
*accomplished after original comment and Rob’s Plug mod
Buon Felice Natale and “Joyous listening!”
Samsung 60" QN65Q7FAMFXZA QLED, Outlaw Audio 976 Pre/Pro, Samsung BDP, Amazon Firestick, Phillips CD Changer
Canare 14 ga - LCR tweeters inside*; Ctr Ch outside
BJC 10 ga - LCR mids “Foamed” & “Plugged**”, inside* & out
8 ga Powerline: LR woofers, inside* & out
*soldered **Rob the Man (Xschop)
LR: Tri-amped RTi A7 w/Rotels*. Woofers - 980BX; Tweets & Mids - RB981*
Ctr Ch: Rotel RB981* -> Bi-amped CSi A6
Surrounds: Rotel 981* -> AR 12 ga -> RTi A3
*all connected w/Premiere ICs
5 Subs: Sunfire True SW Signature -> LFE & Ctr Ch; 4 Audio Pro Evidence @ the “Corners”
Power Conditioning & Distribution:
4 dedicated 20A feeds; APC H15; 5 Furman Miniport 20s -
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
But seriously, pretty different application and much thicker so absorbs lower frequencies and vibrations like you get inside a tire, but cool just the same.
Reminds me a little of my Tannus Armor inserts on my mountain bike tires. Quieter but mainly for flat prevention. Used to get a couple every year and haven't had one in the last 10 years. It was always thorns believe it or not!
George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
Logitech Squeezebox Touch Streamer w/EDO applet
iFi nano iDSD DAC
iPurifier3
iDefender w/ iPower PS
Custom Steve Wilson 1m UPOCC Interconnect
iFi Mercury 0.5m OFHC continuous cast copper USB cable
Custom Ribbon Speaker Cables, 5ft long, 4N Copper, 14awg, ultra low inductance
Custom Vibration Isolation Speaker Stands and Sub Platform -
Bump for Vsat. and another newbie. Full mods or go home.Don't take experimental gene therapies from known eugenicists.
-
Lol. Santa's slippin', I still haven't gotten the 16uf Black Dragon caps that I asked for.
DANG! Was I supposed to talk to Santa about these Rob? -
I have used the Armacell on the outside of a few sets of the Polk MW basket myself. Did not have any trouble with it. Now, after I install my phase plugs I am trying this too. Just installed Silver Dragon face plates instead of the Made In Red China factory flimsy one on my SDA 2b's. Oh how nice to tighten the tweeter up without a huge bend in the corner of every one of them. They look and sound fantastic! One of the best mods yet! Even my dogs Raggi and Me Pal agreed. Soon as I was done installing them and turned on the music they ran right in! So you may wonder, where are the speakers that's one crazy room! Its my "office" where I retire and work on everything. The other image is of Me Pal sticking his tongue out at anyone who do not have the Silver Dragon face plates yet and Raggi Head Banging to Metallica $9.98 CD and me. LOL!!
-
Lol. Best review ever.
Did you use black rouge polish on those?Don't take experimental gene therapies from known eugenicists. -
Silver Dragon Polish... But, it was cold here last night! I did not do anything but a very quick job. Like I said, office setup. Looks Peachy Keen to me here in Greenbow Al. Karen Dalton never sounded so good.
-
No worries, I deleted them and ran the DC28F silks.Don't take experimental gene therapies from known eugenicists. -
I do recall seeing you some caps one time but I sure don't recall talking to you about any 16uF's. Why didn't you text or call me and curse me out or something man! Thanks for letting me off the hook so easily but never expect the same thing from me! Lol! I would have called you and bugged your @ss.
https://www.youtube.com/watch?v=WXzsVDl08A4