Phase Plug design for MW65xx
Comments
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skipshot12 wrote: »Has anyone done the phase plug mod on the sda srs? Thats a lot of drivers.
Would like to hear a pair with that mod…
Skip
It was done on the CRS+ with less than favorable results.
DK supplied some spare MW6511s for Rob to mod; the SDA drivers. They weren't listened to and Sensitivity Testing wasn't done on them to compare to the 6511s that were in his CRS+. If you read through the thread again you'll see that the suspensions were sagging by around 1/8" which would put the voice coils badly off center in the gap.
This needs to be revisited with Sensitivity testing comparing the outputs of the phase plugged drivers with the non phase plugged ones, including the MW6510s which Rob supplied.George / NJ
Polk 7B main speakers, std. mods+ (1979, orig owner)
Martin Logan Dynamo sub w/6ft 14awg Power Cord
Onkyo A-8017 integrated
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Custom Steve Wilson 1m UPOCC Interconnect
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Custom Vibration Isolation Speaker Stands and Sub Platform -
Gardenstater wrote: »skipshot12 wrote: »Has anyone done the phase plug mod on the sda srs? Thats a lot of drivers.
Would like to hear a pair with that mod…
Skip
It was done on the CRS+ with less than favorable results.
DK supplied some spare MW6511s for Rob to mod; the SDA drivers. They weren't listened to and Sensitivity Testing wasn't done on them to compare to the 6511s that were in his CRS+. If you read through the thread again you'll see that the suspensions were sagging by around 1/8" which would put the voice coils badly off center in the gap.
This needs to be revisited with Sensitivity testing comparing the outputs of the phase plugged drivers with the non phase plugged ones, including the MW6510s which Rob supplied.
His 6511 SDA drivers were defective IMO. Actually never opened up ANY set of MW's that looked like that before. How does that NOT affect BL and driver sensitivity?Don't take experimental gene therapies from known eugenicists. -
skipshot12 wrote: »Has anyone done the phase plug mod on the sda srs? Thats a lot of drivers.
Would like to hear a pair with that mod…
Skip
My offer still stands to plug every driver from @ptrooper's the MonolithsDon't take experimental gene therapies from known eugenicists. -
Another 6511 saved from the scrap heap with a new 3.6 ohm coils and base plate ID clearance....
Don't take experimental gene therapies from known eugenicists. -
Did it have the sagging suspension like DKs or was it too mangled to tell?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 -
It was sagging, but not that bad. I heated the spider with hair dryer, let set upside-down while cooling. I'll get another 6511 eventually and A-B the 6502's (better suspensions) in 8TL-SDA circuits.
The JBL 3.6 ohm coils are perfect replacements for 6502's and 6511's.Don't take experimental gene therapies from known eugenicists. -
Thought I'd post this here since it was a phase-plugged 6502 that developed a large crack in the surround and creased the paper cone. These were in may FIL's billet 5Jr's. Luckily he didn't blow the voice coil. I decided to experiment with a replacement carbon fiber cone since it already had the butyl surround glued to it.
I simply chiseled off the old rubber surround and cut the old cone out leaving just enough of it attached to the coil and the electrical leads remained attached. Saves a TON of time and work. Then I cut out the carbon fiber cone center to 1.5" and glued it right to the base of the old cone. The glue I used is Superglue Fix-All and flowed all the interfaces nicely front and back of the CF cone.
Will let set a few hours and glue surround to basket then test on the 5Bs...
Don't take experimental gene therapies from known eugenicists. -
That surround looks twice as big as the old, is it or is that a photo misnomer?
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Do you have a microgram balance? Just wondering about how the weights compare and also of course stiffness if you have any idea.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 -
Just meaured a CF surround and the fold-over is 0.50' wide on the CF, as compared to 0.40" wide on the factory. Th CF surround does feel a little more weighty however.
No uG balance here, but interestingly the CF cone and heavier surround feel about same weight as old one I cut out, so the CF cone itself must be lighter?. The CF is MUCH stiffer than the factory paper cone and was very hard to cut with a new scalpel. It did not fray as that was my worry cutting it.
Later, I plan on building a set of omnidirectional drivers using these CF cones, so was good practice working with them....
Don't take experimental gene therapies from known eugenicists. -
Bottom/center dry. Now have the surround glued and weighted down...
Post edited by xschop onDon't take experimental gene therapies from known eugenicists. -
Cleaned up edges and used a 10mm leather punch for the bolt head clearances...
Ill do a comparo after dinner...
It is the phase-plug thread ya know...
Post edited by xschop onDon't take experimental gene therapies from known eugenicists. -
Loctite already set, so gave them the same wintergreen oil solution as I do the factory surrounds...
Sad Old Red up first...
Don't take experimental gene therapies from known eugenicists. -
Mick, Sade, and Sting all passed the the test with flying colors.
I wouldn't hesitate to do this repair again. The cone holds it shape at very high volume, zero distortion and hard to tell a difference between the plugged 6502 with damped paper cone.Don't take experimental gene therapies from known eugenicists. -
Pet Shop Boys midrange was crystal clear with high volume accompanying bass...
https://youtu.be/wz4pQGxK25Y?si=x2P2f6nYeGwTJ7UC Don't take experimental gene therapies from known eugenicists. -
Nicely done!!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 -
Definitely keepers. Here's the carbon Wuhans I used...I'll be ordering a few more.
Time to go listen to the SDA's.
https://www.ebay.com/itm/193941704625?var=494136088548Don't take experimental gene therapies from known eugenicists. -
Recent Danny Richie video where he describes the midwoofers @6:25:
"We did an 8 ohm and a 16 ohm version and the 8 ohm version you see here in the NX Studio Monitor, and we went all out with the design on it; polymer chassis, lightweight paper cone, copper shorting rings in the motor structure, all copper coated motor structure, I mean we did everything on this thing, venting through the front, solid aluminum pole piece copper coated *, the works, and the result was one of the best sounding woofers there is on the market to this day."
* I looked the driver up on his website and, yes he did mean solid aluminum phase plug attached to pole piece
https://gr-research.com/product/m-165nq/
https://www.youtube.com/watch?v=7h72KXd8Q3c 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 -
Yet another example with a metallic phase plug, aluminum shorting ring, and copper capped pole piece:
http://nedlab.com/wp/wp-content/uploads/2014/06/Peerless-850467-woofer.pdf
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 -
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 think we talked about it before but most drivers with a plug are very deep cones. The Polk cones are not very deep in comparison which is why I think you see mixed results.- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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I think we talked about it before but most drivers with a plug are very deep cones. The Polk cones are not very deep in comparison which is why I think you see mixed results.
I do remember someone presenting that "opinion" without any in depth rationalization, in a thread that got nuked by admin due to lack of civility. Doesn't have any bearing on the elimination of the resonant cavity under the dust cap, the greater cooling of the voice coil resulting in less power compression, or the reduction in distortion due to reduction of change in inductance and impedance with displacement of the coil.
I presented information above somewhere that the highs tend to be produced near the center of the cone, ie. near the phase plug. The cone tends to act as a waveguide in this case. The phase plug tends to make the driver behave more as a point source of sound for the highs, which is desireable. But does this look all that much different from the depth of the Polk MWs?
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 -
To refine my view point. A plug shaped like the original dust cap would most likely be better received by the collective- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit.
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To refine my view point. A plug shaped like the original dust cap would most likely be better received by the collective
Maybe based upon keeping the looks more traditional, especially if it was black.
But I would hate to lose the benefit I got in my 7Bs where the harmonics are much better dispersed to the point where I can listen just fine way off axis.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 -
If I recall Ray liked them in the traditional models but not the sda?
Either way, this hobby is all about fun and if you like it that's all that matters!
I just think it's more invasive than most folks want to go- Not Tom ::::::: Any system can play Diana Krall. Only the best can play Limp Bizkit. -
If I recall Ray liked them in the traditional models but not the sda?
Either way, this hobby is all about fun and if you like it that's all that matters!
I just think it's more invasive than most folks want to go
Ray didn't test in anything other than his SDA CRS+, but the driver that he supplied Rob with had a sagging suspension and off centered voice coil. Rob didn't modify the existing driver, it was ones that Ray had in storage somewhere and they weren't listened to prior to Rob's modification.
I miss his posts.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 -
And oh yeah, I continue to be happy with this mod. Remembering back, the first thing I noticed is that hi hat cymbals sounded so much more natural (you know that tssss sound), probably due to less constructive and destructive interference of those higher harmonics which are close to the crossover point of the midwoofer. It is those frequencies that I think the phase plug has acoustical influence on the wavefront due to it's size relative to the wavelength.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 -
Glad work has been going on behind the scenes."Sometimes you have to look to the past to understand where you are going in the future"Harry / Marietta GA
