Lacking bass on RTA 11T

barakus

I don't know if I'm expecting too much from this speaker or if something is wrong with mine. My previous primary speakers were a pair of Monitor 7Cs, and picked up this pair of 11Ts off of eBay a couple of months ago because I wanted something a little more modern-looking and because I couldn't get proper imaging with the 7Cs with the stands I have and the room layout I'm dealing with.

When I unpacked the speakers, I hurriedly connected one to make sure it worked and to get that magical first listen with the 7C still connected to the other channel. My initial feeling was that the 11T was broken, but it seemed to be much quieter than the 7C, so naturally it wouldn't sound as good. After setting both speakers up and giving a quick listen before bedtime, I noted the positive aspects of them - a less boxy sound and significantly better imaging.

The following day I switched out the old SL2000s (or are they SL2500s?) for the RDOs I had previously put in the Monitors and tweaked everything as best as I could. They sounded GREAT in home theater service, but I felt like I was missing some of that vintage Polk sweetness when I listened to music. It is important to say that I do have a subwoofer which I tend to set pretty unscientifically.

Last night I tried disconnecting the subwoofer to hear what the 11Ts sounded like on their own, and was somewhat surprised to hear a distinct lack of bass. They are in phase and I removed each midwoofer and powered them individually to make sure they're all working. I also did the leak test by pushing in woofers to make sure they're airtight.

I ran some frequency sweeps on DVE through the speakers, and, aside from a little peak around 60Hz, there really isn't a whole lot of action from the woofers below about 100HZ. The specs say that their -3 db point is 29Hz, but it seems like it's more like 150Hz. I tried removing a woofer and connecting it directly to my receiver, and it really doesn't seem like they're trying very hard until somewhere in the 100-200Hz range. My receiver does not have a high-pass filter.

I feel like I've gone on for far too long already, but does anyone have any helpful advice for me? Is it possible for more than one woofer to somehow have gotten lazy or something over the last 19 years? All the drivers and the crossovers look brand new, and there are no mechanical noises. It just seems like they're lifeless in the bass range.

riglehart

I have both 11T and 7s. The 11T sounds better (fuller) than the 7s, in my opinion.

You might have a bad capacitor in a (or both) crossover or something. They do fail over time. I rebuilt the crossover in my 11T because I knew it would help and I plan on keeping them for a long time. Plus I had a weak poly switch and decided to do the whole works while I was fixing that. They sound great.

F1nut

Is it possible for more than one woofer to somehow have gotten lazy or something over the last 19 years?

Yes, it is. Another possible cause for the issue you're having is the crossover. Check all the solder joints and the lead wires on the inductors. Also, closely inspect the PR's for issues, such as separated parts at the back end as the PR is responsible for the low bass.

kawizx9r

Since you'll be opening up your speakers and checking out your x-overs, thats the perfect time to perform some common SDA treatments. I recommended Jimbo do the same to his monitors and he did right away during his restoration process. Get yourself some dynamat for the drivers' baskets and seal those babies up with some mortite caulk cord (only 5 bucks at home depot) and you'll definitely notice the tighter more accurate bass....I know I did from my speakers

barakus

It's probably not a very good way to tell, but I did detour the crossover and run a midwoofer directly to the source, and, although it was outside the enclosure and I couldn't hear the bass, it really didn't seem like the speaker was moving as much as it should be at low frequencies. Another completely subjective piece of evidence is that the mids and radiators don't seem to move as much at high volume as they do in the 7s. The 11's drivers do seem to resist a little bit more when you push them with a finger than the 7s drivers, but there is no evidence that anything is hanging up or anything. Again, they look brand new.

I think if I get time tomorrow I might get the 7Cs out of storage and compare them more thoroughly. According to the specs I've seen, the 11Ts should be more efficient than the 7s, so the fact that the 11T was quieter when I first hooked it up could point to a problem.

Does anyone know what the compatibility between the different flavors of Polk MWxxx woofers are? I'm pretty sure the number is different on the 11Ts and 7Cs. I doubt it would hurt anything to swap the 7s mids with the 11Ts' to see what happens.

F1nut

The mid-drivers do not produce the low bass, the PR does.

MWxxxx drivers are very specific and not interchangeable in function.

barakus

F1nut wrote: »

The mid-drivers do not produce the low bass, the PR does.

Yeah, but they incite the passive radiators, and they're not doing a very good job of it right now apparently.

I don't plan on using the 7's drivers in the 11's cabinets for long, just to see if I can get a little more bass. That's not very likely to break anything if I try it for a little while, right? I could use a new amp anyway.

As an aside, I'm curious as to which passive radiator is responsible for what range. Does anyone know which radiator is tuned deeper?

kcoc321

regarding the efficiency I just got some RTA 8TL's and I can say they were more efficient than my 7c's, at the same volume.

The specs in the Vintage Speaker section shows the MW as a MW6510, which I believe is a 4ohm speaker. The 7C's use the MW6502, which is a 8ohm, so there should not be a problem trying them out in the 11's.
link to x-over specs:
http://www.polkaudio.com/forums/showthread.php?t=38755

Do you have the "T's" or the "TL's" ??
I ask because you seemed uncertain about the tweeters that came with the 11's. If you have the "T's" then the RDO-194 is a direct swap for the SL2000's, which are the same as the 7c's.

If you have the TL's, then the upgraded tweeter would be the RDO-198, which replaces the SL2500's and SL3000...I can't speak to how a RDO-194 would sound on a "TL" X-over....

Good news is that if it is just a bad MW, the MW6510's are pretty plentiful in the FS section, since they are in most of the SDA speakers as well.

barakus

kcoc - They're definitely Ts. I can spot --and hear -- those horrible SL2000s a mile away. I thought I saw something about SL2500s somewhere in relation to RTAs, but I'm not familiar with them. Apparently the SL3000s are pretty pleasant, but I surely heard that spike in the treble when I first hooked up the 11Ts.

If the 11Ts can be what I think they can, I'd be willing to replace all the midwoofers, but it seems unlikely to me that all 4 would be bad in the same way. Maybe they got in the direct path of a solar flare and got demagnetized? Ha!

lightman1

barakus wrote: »

Yeah, but they incite the passive radiators, and they're not doing a very good job of it right now apparently.

I don't plan on using the 7's drivers in the 11's cabinets for long, just to see if I can get a little more bass. That's not very likely to break anything if I try it for a little while, right? I could use a new amp anyway.

As an aside, I'm curious as to which passive radiator is responsible for what range. Does anyone know which radiator is tuned deeper?

PR's only reflect what is presented to them. Cabinet desingn, driver array.. etc.

rallyshark

This is kinda weird It really sounds like your source/receiver has the high pass filter engaged, but I know you said it doesn't have one. How about placement? Maybe move them closer to the wall? I would say the problem has to be in the crossovers if placement isn't the issue. I still think the most likely cause is something before the speakers (source/amp/wiring)(out of phase) etc. I would definitely not classify the 11t as having a lack of bass, especially compared to the M7s. I just find it unlikely that both speakers or crossovers have the same problem, but it is possible I also say always revert to the KISS principle when things don't make sense. It's usually something so simple that we instantly overlook it. I hope that helps:)

barakus

I did try hooking one of the 11Ts up to an inexpensive little table radio that has Athena BS1s hooked up to it (ported bookshelves, 5 1/4" drivers) and I think the RTA had less bass than the bookshelf.

It really sort of seems like maybe the magnets in the voice coils got weak somehow, but I've never heard of such a thing. I don't know if that would affect the bass region more than others. They can play plenty loud.

By the way, the speakers are placed too close to the walls if anything. The left channel is less than a foot from the wall behind it and the right channel is in a corner at the same distance from the back wall and less than 6 inches from the side wall.

kcoc321

Have you checked the phase on all your internal wiring? Unlike House electrical, Polk speakers are wired with black as positive...I have to mentally tell myself every time I rehook up my drivers....
Another thought...does your receiver have a "small/ large" speaker setup?
That would send the lows to the Sub....
All I can think of right now.

Good luck...sorry, sounds frustrating......

barakus

Well, I just did a bunch of testing between a 7 and an 11T and have my report.

The 11T definitely plays louder at a given level. I think the reason that the opposite was true on my first listen is that one of the SL2000s that came with the 11T is mostly broken and scratchy. It probably wasn't playing at full volume.

Running a 15Hz - 300Hz sweep through both speakers alternately was interesting. The 11 became audible around 30Hz; the 8 around 45Hz. I would say that as far as average volume goes, the 11T played more of the bass range louder, but it has more of a gentle increase up to 150Hz, whereas the 8 has a bit of a swell around 60Hz where it was doubtlessly playing louder.

I played music through each speaker to compare their bass performance and, after the learning what the sweep test had to teach, found that the 7's bass peak made it appear to be fuller in the bass region. The 11 has more ability to pump out low notes, but it seems less prone to do so. I can't help but feel that there's a certain sweetness to the old Monitor 7's sound that the RTA can't match, but the 11 plays louder and images much better.

My current strategy is to increase the bass level from my receiver one notch and keep the 11s as my primaries. I played Pink Floyd's Welcome to the Machine through the 11s with no subwoofer and managed to get bass I could feel, which probably wouldn't happen with the 7s.

I think I'll try a crossover refresh at some point if I can avoid reading the SRS classifieds.

Thanks for the help, everyone.

AudioGenics

or.... add an active subwoofer

John in MA

I never had any trouble with the bass in my 11Ts. They easily beat out a lot of other sets of similar quality I owned. Even close to a pair of giant McIntosh speakers I had at the time, assuming you kept the volume low below where the Macs hit their stride.

barakus

jvc wrote: »

or.... add an active subwoofer

I have an active subwoofer that's crossed over at around 100Hz. I would prefer to get as much bass as possible from the mains to prevent muddying up musical bass notes with crossover point problems. I'd prefer to set the sub to 60 Hz or so.

The specs on the RTA 11T indicate that it should not really need a subwoofer for music. I've always done the subwoofer/bookshelf thing until I started getting into vintage polks, and I prefer the warmer full range sound of a larger speaker handling a full range over the boom-tisk of satellite/subwoofer.

Maybe I just have unrealistic expectations about bass. I bought a pair of Grado SR-60 headphones based on overwhelming positive response, but I find them rather thin and shrill.

Pauly

What AVR are you using? And how do you have it setup? I get tons of bass off mine. No sub, fronts set to large and i always play in Pure Direct mode using Pioneer Elite VSX 92TXH.

Pauly

barakus

Pauly wrote: »

What AVR are you using? And how do you have it setup? I get tons of bass off mine. No sub, fronts set to large and i always play in Pure Direct mode using Pioneer Elite VSX 92TXH.

I have a Kenwood VR-305. The manual can be found here if you want to see it: http://tinyurl.com/nhl4pj I see that the specs indicate a 40Hz-20KHz range. Hmmm. But I'm not really expecting much from the sub-40Hz range and have not had bass problems with this receiver connected to other speakers.

The Kenwood is pretty basic, and I have it set up for basic stereo operation with a powered subwoofer connected to its subwoofer output. I really don't think the receiver puts a high pass filter on the main channels when a subwoofer is connected, but I tried disconnecting the subwoofer output and turning the subwoofer output off on the receiver.

Ron Temple

The 11s are 6 ohm nominal speakers that like current. I've heard them with hefty ampflication and bass is deep and profound. You're giving them a fraction of what they need to perform optimally. That Kenwood just doesn't have the balls to drive them.

everpress

Ron Temple wrote: »

The 11s are 6 ohm nominal speakers that like current. I've heard them with hefty ampflication and bass is deep and profound. You're giving them a fraction of what they need to perform optimally. That Kenwood just doesn't have the balls to drive them.

My HT receiver has a fraction of the power of many out there and mine drives my 11TL's like no man's business... Everyone reports these RTA's to have tight and punchy bass, so if you are looking for boom-power, these supposedly don't have it.
These are my primary speakers and I use them for both 2-channel stereo listening and 5.1 HT listening and I can say that they are impressive to me. They do not "rattle the chest" like a theatre, but they come so close that it make s me think that my set up is close to complete.

The 11T/TLs are amazing in the imaging department and I think for the size of my listening space, they might even be a little too much (no, no one can have them), but they are detailed in every frequency range I've put them through.

Ron Temple

everpress wrote: »

My HT receiver has a fraction of the power of many out there and mine drives my 11TL's like no man's business... Everyone reports these RTA's to have tight and punchy bass, so if you are looking for boom-power, these supposedly don't have it.
These are my primary speakers and I use them for both 2-channel stereo listening and 5.1 HT listening and I can say that they are impressive to me. They do not "rattle the chest" like a theatre, but they come so close that it make s me think that my set up is close to complete.

The 11T/TLs are amazing in the imaging department and I think for the size of my listening space, they might even be a little too much (no, no one can have them), but they are detailed in every frequency range I've put them through.

His Kenwood AVR is 80w RMS 40-20khz @ 8ohms. It's running out of gas driving lower impedences. Not saying that it doesn't sound alright or that an AVR can't drive the 11Ts, but bass response is going to fall behind with that combo.

everpress

Ron Temple wrote: »

His Kenwood AVR is 80w RMS 40-20khz @ 8ohms. It's running out of gas driving lower impedences. Not saying that it doesn't sound alright or that an AVR can't drive the 11Ts, but bass response is going to fall behind with that combo.

Thanks Ron; I just looked at reviews for his receiver; there are many many complaints on the music quality and most especially the bass.

barakus

Ron Temple wrote: »

His Kenwood AVR is 80w RMS 40-20khz @ 8ohms. It's running out of gas driving lower impedences. Not saying that it doesn't sound alright or that an AVR can't drive the 11Ts, but bass response is going to fall behind with that combo.

I believe the 80W figure is only in 5.1 mode. It's 100W/channel in stereo mode. I'm certainly not saying it's a great source, but I think it should be sufficient. You may be right that I could get more bass out of a better amplifier, but I can drive the 11Ts to painfully loud levels without any obvious distortion.

Coincidentally, I just had a cheap mini system delivered to my house yesterday for use in my bedroom with the pair of small Athena bookshelf speakers I mentioned before. It's a Sony CMTBX20i, which, according to the manual, is 18 watts per channel at 10% THD. I think I'm getting more bass out of this little system -- at least at low volumes -- than out of the 11Ts.

The whole problem is somewhat moot because I have a subwoofer, but as I said before, I'd like to have the sub doing as little as possible. I don't really like the boomy sound for anything but movie explosions and whatnot. My focus is certainly on music sounding good over home theater.

EDIT: I just started reading reviews of the VR-305 and the first one says it rivals the guy's Bose system! It must be good!

Conradicles

Are you sure one of your drivers is not wired out of phase? This will kill all bass.

barakus

Conradicles wrote: »

Are you sure one of your drivers is not wired out of phase? This will kill all bass.

If that was the case, I think I'd be too embarrassed to post again. I'm pretty sure everything's wired correctly, but I'll double-check tonight.

Ron Temple

barakus wrote: »

I believe the 80W figure is only in 5.1 mode. It's 100W/channel in stereo mode. I'm certainly not saying it's a great source, but I think it should be sufficient. You may be right that I could get more bass out of a better amplifier, but I can drive the 11Ts to painfully loud levels without any obvious distortion.

Look at your manual again. It's 80w X 2, .7HD, 40-20khz. The rest of the specs showing 100w are at 1khz and per channel. This AVR is giving it's best in 2 channel, but it's a tad underpowered to driver lower impedences. The 11Ts are fairly sensitive and will get loud, but your bass response is going to be weak. You're not hearing it with the M7s because you're within your AVRs FR. The amount of power needed to drive the 11s below 60hz is probably sucking the life out of the PS. I'm not dissing your gear, but I think it's a bit of a mismatch and the root of your problem.

barakus

Ron Temple wrote: »

Look at your manual again. It's 80w X 2, .7HD, 40-20khz. The rest of the specs showing 100w are at 1khz and per channel. This AVR is giving it's best in 2 channel, but it's a tad underpowered to driver lower impedences. The 11Ts are fairly sensitive and will get loud, but your bass response is going to be weak. You're not hearing it with the M7s because you're within your AVRs FR. The amount of power needed to drive the 11s below 60hz is probably sucking the life out of the PS. I'm not dissing your gear, but I think it's a bit of a mismatch and the root of your problem.

Thanks, you might have a point. Do you have any receiver suggestions? For some strange reason I would like to have some surround sound capability even though I don't plan to ever set it up.

I've seen the Onkyo TX-SR606 recommended a lot, but that's rather pricey. I can't pay twice what I paid for the speakers for a source.

Ron Temple

I'm personally not a fan of the 6xx series of Onkyo. Not because it's a bad AVR. It's great if you never want to upgrade again and have easy to drive speakers. If you want a multi-channel AVRI'd find a reasonably priced AVR with pre-outs. A recommended 2 channel receiver would be the HK3490, 120wpc, 4 ohm stable and can be had for < $300. Doesn't have the video bells and whistles, but it's a great option for cheap power and audio quality.

John30_30

barakus wrote: »

Yeah, but they incite the passive radiators, and they're not doing a very good job of it right now apparently.

I don't plan on using the 7's drivers in the 11's cabinets for long, just to see if I can get a little more bass. That's not very likely to break anything if I try it for a little while, right? I could use a new amp anyway.

As an aside, I'm curious as to which passive radiator is responsible for what range. Does anyone know which radiator is tuned deeper?

When I tapped on mine with a finger, I heard the bottom one is a 5th deeper. Like these guys have said, if you don't have enough power, they won't put out the bass. If you do have enough, they're a testimony to some very intelligent design.

Confession time: I traded off my set of RTA11T's a few months ago. The guy had some SDA 2's, which pull 4 ohms, iirc, and a Harmon-Kardon receiver, which maybe pushed an honest 70-80 wpc, not quite enough for the bass on those. So he was down in the mouth because his buddy had told him the vintage Polks were the way to go.

He demo'd rap music on my towers that I'd brought over. And I learned yet another test of a good set of speakers is to make something you can't stand sound very good. And as the guys have also mentioned, the RTA's pull a nominal 6.
He couldn't afford a bigger amp at that time, but wanted to be sure he'd have the bass to shake the walls. Those speakers do put out bass. The 'music' was definitely stretching those passives.






huh-huh. He said 'Intelligent Design.'

rallyshark

Brilliant deduction guys! I didn't even think to look up the specs on the receiver he has:o So yeah, that definitely sounds like the solution for no bass:) I have a pair of M11Ts(xover,RDO), and they are being pushed with a Marantz SR6003. The little Marantz seems to do quite well considering it is only 100W RMS. I think that is all channels driven though. It may be slightly higher in stereo. I think it's supposed to be 125W or so at 6ohms. Anyway, I'm very happy with my 11T's, so I would definitely say invest in a receiver upgrade. If new or refurbished isn't within your price range, there are tons of decent used receivers out there that would do the 11Ts more justice than the Kenwood. If it helps I had a Technics receiver that was 120W RMS with .05 THD at 8ohms, and the Marantz kicks the Technic's butt with a lower power rating! In other words, I can personally attest to the fact the a better AVR can make a big difference. Don't let the lower power ratings on some of the receivers you may find throw you off. 50W of HK, Onk, Marantz, etc. will blow away many receivers rated 100+ watts. It's not just about watts. I believe the current and watts is what makes to true difference. Someone will correct me if I'm wrong;) I hope that helps, and good luck!