RTA 12B General Questions
Comments
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I did and it's air tight on both speakers. The bass is there it's just slightly understated - maybe an artifact of burn-in for these Clarity caps that will improve in time? Or maybe I got used to overstated bass on the M10's. Regardless, it's not a big deal.
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Perhaps it's more a matter of tighter bass instead of the rather bloated bass of the 10's.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."
President of Club Polk -
Dynamat Xtreme (or equiv.) and xschop semi rings will tighten that bass up even further. The rings especially gave me more impactful bass with the 7Bs. You have some bracing though and I had none whatsoever, on a pretty wide baffle. The dynamat was more of an improvement to the naturalness of bongos and tom toms.
PS: If you read the Julian Hirsch review of the Model 10, he found them to have a pretty huge amount of bass distortion. Those aren't his words those are mine, but he gave the figures in the article.
PPS: In the interest of accuracy, it was 12% distortion at 30 Hz and 10W, which would be pretty loud.
For comparison, this is from his review of the 12B. Definitely smoother bass and lower distortion:
Post edited by Gardenstater onGeorge / 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 -
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Thanks guys, I think you may be right on this being a case of tighter bass. I already have the dynamat xtreme in play + hurricane nuts. I might look into xchop semi rings as well. One thing I'm going to do is to set up an "A-B" comparison since I can easily move these speakers into and out of the room. Then we can compare apples to apples!
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I learned that the 12B has a particle board cabinet that is constructed using a "special laminate shear damping technique. They must have used at least 2 layers of particle board with a viscoelastomeric adhesive in between. That might help to tighten the bass.
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 -
As F1 wrote above, your speakers are capable of tight, low bass. I recall @westmassguy working on a pair of 12b's years ago (upgrades similar to yours), commenting on how much good quality low bass they produced. My original 12's go low, and yours are more refined, with larger cabinets and should do better. You probably know this, but you can play with room placement - closer to rear walls and corners will enhance bass. Also, make sure soundwaves and air can move from the midwoofers down through the polyfill easily to the PR's. I've found that polyfill, packed too tight behind the midwoofers, can diminish bass and slam. Experts on the forum preach high-current amps for Polk speakers, and you're correct that the 12's thrive on current (12b's are 4 ohm). My speakers came alive with slam and bottom end using high-current amplification. My amps crank 1350W into 4 ohms, which is probably overkill, but I like what I hear, lol. Speaker cable is another factor, as some cables enhance good bass reproduction. Sounds like you're getting good results with your upgrades. Listen to music you've known for years with a prominent low bass line (upright bass, bass guitar, low piano etc.) - you should hear more than a "suggestion" of what is going on, and the pitch of each note should be apparent. One-note bass means something needs tweaking.
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Jazzhead brings up good points, especially placement. You will get the best bass when your speakers are 5 to 6 inches off the rear wall.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."
President of Club Polk -
OK, issue resolved! While it did pass the air tightness test, when I checked the screws on the MW's and PR's they had become rather loose. I guess the Armacell gaskets had slowly deflated and there wasn't much kinetic transfer to the baffle. Now with screws nice and tight, bass is clean and punchy like it should be - and more detail compared to the M10's.
Still going to do the "A-B" test when I have a chance. -
There's a reason the original gaskets are paper thin.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."
President of Club Polk -
The Armacell will flatten out nicely, you definitely do not want to do it all at once you'll risk stripping screw holes. Come back a few days from now and check once again.
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OK, just to update - the M10 vs. RTA 12B comparison never happened. That's because the RTA 12B is hands down in a different league vs. the M10. I've spent these past few months still in awe every time I listen, and it's been hundreds of hours thanks to a streaming subscription to the world's largest hi-def library.
Really, the sound is so clear and detailed from 20 Hz to 20+ kHz, it literally sounds like I have musicians playing live in my living room. Not at all shouty, and with well recorded and mastered tracks, glasslike transparency. Thanks again to all of you helping me out on this project. Veneering these for sure!
And today I just picked up a near mint pair of SDA 2B's for $100. I'll upgrade these this winter when I have more time, and THEN we'll have a proper comparison shootout. -
Heh, Heh, Heh. Can I say rabbit hole?? Well yes, because I did the same thing. 10's, 12's, 7's, SDA 1C's, SDA 2B's.........where does it end. Enjoy the journey.
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Yup, rabbit hole for sure - but enormously fun! For me it all started 5 years ago when I picked up a pair of M5 series 2's. Got them home and one didn't work at all and the other sounded awful. My first thought was - that's $60 I just wasted. Then I stumbled on this forum and got them fixed and sounding great. They still get daily use every night at bedtime.
Regarding my RTA-12's - I've listened to top of the line Vandersteins driven by $50K+ gear - and these actually sound better. I seriously doubt the 2B's will outperform the 12's but I have yet to spend time listening to upgraded SDA. We'll see! -
Yup, rabbit hole for sure - but enormously fun! For me it all started 5 years ago when I picked up a pair of M5 series 2's. Got them home and one didn't work at all and the other sounded awful. My first thought was - that's $60 I just wasted. Then I stumbled on this forum and got them fixed and sounding great. They still get daily use every night at bedtime.
Regarding my RTA-12's - I've listened to top of the line Vandersteins driven by $50K+ gear - and these actually sound better. I seriously doubt the 2B's will outperform the 12's but I have yet to spend time listening to upgraded SDA. We'll see!
Aaaaa grasshopper ...... -
....much to learn.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."
President of Club Polk -
And ya'll think I like the ol' 15s a little too much ... 😳😂
Glad @Sitka is enjoying the forum and his vintage Polk speakers, though!
Vandersteen, just sayin'.
Brian
One-owner Polk Audio RTA 15TL speakers refreshed w/ Sonicap, Vishay/Mills and Cardas components by "pitdogg2," "xschop" billet tweeter plates and BH5 | Stereo REL Acoustics T/5x subwoofers w/ Bassline Blue cables | Rogue Audio Cronus Magnum III integrated tube amp | Technics SL-1210G turntable w/ Ortofon 2M Black LVB 250 MM cart | Sony CDP-508ESD CD player (as a transport) | LampizatOr Baltic 4 tube DAC | Nordost & DH Labs cables/interconnects | APC H15 Power Conditioner | GIK Acoustics room treatments | Degritter RCM -
Thanks guys - I'll keep an open mind - always willing to learn.
