Polk RTA-12Cs and Monitor 10As... where's da bass???
jon s
Posts: 905
I have a pair of Monitor 10As and a pair of RTA-12Cs (both modded with Sonicaps and new RDO194 HF drivers). While easy to listen to, I feel that the bass on both units seem to be on the light side. I am not one who needs a lot of bass and actually prefer the bass to be flat but when comparing the Polks with any other speakers, the passive radiators just do not have that tight extended bottom.
When listening to a bass cello, it sounds more a deeper viola. Listening to Yoyo Ma is a good example. One title comes to mind for a bass test, on the soundtrack of "Titanic", the song "Leaving Southampton" has a great opening low bass drum which rattles the walls with other speakers but on the Polks, it is nearly non-existent. Even on my Polk RT2000Ps, the bass output is clearly deeper than the passive radiator drivers.
My feeling is that the twin 6.5" mid-woofers on the speakers cannot go that deep due to their small size and therefore do not have the energy to really excite the radiators enough to generate low frequencies. Generating a low frequency signal below 50Hz does not really excite the radiator at all. In fact, using tone controls on the amp does not noticeably affect the bass at all, even when boosting the bass level up by 10dB. In order to get the bass up, I needed to add a Polk PSW300 sub inline. While this augmented the bass, I would prefer not using a sub if necessary.
I do not have any air pressure leakage from the cabinets and all the drivers work fine.
Does anyone else notice this trait with the early Polks?
When listening to a bass cello, it sounds more a deeper viola. Listening to Yoyo Ma is a good example. One title comes to mind for a bass test, on the soundtrack of "Titanic", the song "Leaving Southampton" has a great opening low bass drum which rattles the walls with other speakers but on the Polks, it is nearly non-existent. Even on my Polk RT2000Ps, the bass output is clearly deeper than the passive radiator drivers.
My feeling is that the twin 6.5" mid-woofers on the speakers cannot go that deep due to their small size and therefore do not have the energy to really excite the radiators enough to generate low frequencies. Generating a low frequency signal below 50Hz does not really excite the radiator at all. In fact, using tone controls on the amp does not noticeably affect the bass at all, even when boosting the bass level up by 10dB. In order to get the bass up, I needed to add a Polk PSW300 sub inline. While this augmented the bass, I would prefer not using a sub if necessary.
I do not have any air pressure leakage from the cabinets and all the drivers work fine.
Does anyone else notice this trait with the early Polks?
Post edited by jon s on
Comments
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I'd suggest there's something wrong with the speakers or your set up. Have you checked for air leaks? How close to the back wall are the speakers?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 -
"He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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The PR on my RTA 12C's really move when I put the spurs to them. Of course my idea of bass is Nine Inch Nails but even Fiona Apple on the piano really makes the PR dance. Take the PR out and take a look at it make sure the glue has not given out. Well actually since you say the problem is with both your 12's and the M10's maybe it's your ears. Both those speakers have a similar voice, it's possible your ears are tuned off at the frequency they are producing??? As a relative noob I should stop now before I step further in quicksand I may not make it out of!
AbelPolk Audio RTA 12c's, Monitor 7c, Monitor 5JR+, SDA CRS+ -
One speaker out-of-phase with the other??? That's a real bass-killer.
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Hi. I have the monitor 10b with no mods and they sound great in the bass department (so much bass I had to add weather stripping around my windows to eliminate rattles and buzzing). For me when I was driving them with an Onkyo receiver the bass in "direct" mode was very lacking. The Onkyo was rated at 85 wpc and the 10s never seemed to "come alive" while this receiver was powering them. Now I have them hooked up to an NAD amp (150 wpc) and they sound fantastic. I would recommend you drive them with at least 100wpc all the way up to 200+ wpc. The more power you give the 10s the better they sound.
Speaker placement is also critical to get the very best sound. Monitor 10s sound their best when placed 3 feet from any wall and 6'-8' apart on speaker stands. One thing that made a HUGE difference in the quality of the sound being produced by the 10s was speaker wire. When I used Monster wire they sounded like dull pieces of shiot. When I went to 14 gauge copper wire from a local electronics store the sound improved even more. Then I decided to upgrade the speaker wire again and now I am getting the best the 10s have to offer with my current setup imo.
A few things to check.
1. speakers hooked up in phase
2. if using a HT receiver make sure the front speakers are set to LARGE
3. upgrade your speaker wire if you are using some cheap crap. 14 gauge wire will be a little overkill but it will get the job done nicely plus it looks better than little thin,frail, wire. -
jon s,
What kind of amp are you using? -
The LSi9's have a mid bass hump that may fool you into thinking you're getting more bass, but you're not. Both of those vintage Polk's are capable of producing low bass, so unless there is a problem with the speakers, it's got be something else causing the issue.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 -
I am currently using an Onkyo TX-NR905 140wpc receiver. I also used an Acurus DIA100 integrated amp earlier with the same results. The speakers are about 1.5 ft away from the rear wall. The RTA-12Cs replaced a pair of Polk LSi15s which had a lot more bass than the RTAs. They are not out of phase. They are about six feet apart and I sit about seven feet away from them...
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According the the Polk manual, moving them closer to the wall will result in more bass.
May be worth a try.
In my living room, may SDA's sounded the best about 3" from the wall. -
The speakers are about 1.5 ft away from the rear wall.
Yep, too far away.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 -
yep... they were too far away... shoved them against the wall and the bass was better, not perfect but better... btw, did a frequency sweep of the speakers... used a tone generator and a modded rat shack SPL meter to compensate for the uneven response...
Test was done with mic @ 1meter from midwoofers at 90dB reference level...
Hz Level (dB)
25..........-3.0
31.5.........0.0
40...........1.5
50...........1.5
63...........1.5
80...........2.5
100..........2.0
125..........0.5
160.........-2.5
200.........-2.0
250.........1.5
315.........1.5
400.........2.0
500.........0.5
630.........1.0
800.........2.0
1kHz........2.0
1.25........3.0
1.6..........1.5
2.............0.5
2.5..........0.5
3.15.........0.5
4.............1.5
5.............3.0
6.3...........4.0
8..............3.0
10............1.5
12.5.........0.5
16..........-2.0
20..........-4.0 -
I use to have this same issue, but speaker positioning was everything. Good luck
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yep... they were too far away... shoved them against the wall and the bass was better, not perfect but better...
As suggested by many, you're going to have to keep playing with position until you get them dialed in. For example, Conradicles says his sound best at 3" while mine sound best at 6". A movement of as little as 1/2" can make or break the sound. You'll know you have it right when the low bass growls, none of the thumpy crap.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 -
As suggested by many, you're going to have to keep playing with position until you get them dialed in. For example, Conradicles says his sound best at 3" while mine sound best at 6". A movement of as little as 1/2" can make or break the sound. You'll know you have it right when the low bass growls, none of the thumpy crap.
No kidding. The same SDA's of mine sound better in my huge garage about 9.5" from the wall and closer together (4 foot). Speaker placement is huge in the sound produced.;)
