Why does Audyssey set crossover to 250hz for Polk T15?

Lapparty

Hi everyone! I've just recently received my new polk t15 speakers and for some strange reason I can't get Audyssey to calibrate them to a reasonably acceptabe crossover. ...which means that I'm loosing on some great EQ even if I set crossover to 100hz manually.

I ran multiple calibrations but it always got back to me with either 200hz or 250! Which tells me something is definitely up. Especially because before them I was using Onkyo's HTIB extremely small plastic speakers (SKF-558) and it calibrated them fine to 120hz.

Do you have any suggestions why this might be the case? Could it be a faulty unit or is it some kind of user error?

Thanks in advance!

Emlyn

Are you using a subwoofer? If so, what model is it? Also, are the T15s on stands or sitting on a cabinet or bookshelves, or are they close to a wall?

Even if you are using a subwoofer you could still set the T15s as "Large" in setup manually without causing any significant issues. The -3dB output (clean bass output) on the T15s goes down to 65Hz if optimally placed. My suggestion is to run Audyssey first then play around with the speaker settings manually to see if you can hear a difference in bass.

[Deleted User]

As a test try reversing the speaker wire connections on one of the T15 speakers.

Lapparty

Emlyn wrote: »

Are you using a subwoofer? If so, what model is it? Also, are the T15s on stands or sitting on a cabinet or bookshelves, or are they close to a wall?

Even if you are using a subwoofer you could still set the T15s as "Large" in setup manually without causing any significant issues. The -3dB output (clean bass output) on the T15s goes down to 65Hz if optimally placed. My suggestion is to run Audyssey first then play around with the speaker settings manually to see if you can hear a difference in bass.

I do use a subwoofer, it's a Polk PSW110. The T15s are on a cabinet, not equally far from the wall. The left one is ~10" and the right one is ~4" far from it. It's a custom cabinet as the wall behind it is not paralell (see attachment of the layout). The T15s are the front L&R. I'm using a Polk CSM as center (that one is perfect, calibrated to 40hz crossover by audyssey and raised by me to 80hz manually). The T15s are laying on their sides as otherwise they could not fit under the TV and there's no space really to put them further apart.



I'm not sure I can set the speaker size manually before the calibration. I'm using a Denon AVR-X1400H. I can set anything manually after the calibration though but I've read that changing crossover after calibration actually doesn't do any good as there's no EQ applied and there's a dropoff in the output anyway at those frquency ranges (hence why audyssey set to to such high crossover in the first place). I can confirm that too as I can't really tell a difference in bass when changing the crossover to 80hz after the calibration. Maybe a little. The center channel is nice and warm, full of sound but the two T15s are definitely lacking compared to the center.

KennethSwauger wrote: »

As a test try reversing the speaker wire connections on one of the T15 speakers.

I was also thinking that there might be some null going on in the room and I should try different locations for the T15s and see if it helps, but the truth is I don't really have any other place to put them even if it does help and it appears to me that even when leaning close to the T15s themselves I can't hear much bass, especially compared to the CSM with which I could feel bass on my face So it appeared to me that it's not just at the main listening position where it's lacking so I gave up on this idea. I've even tried changing the pair up (as they are on their sides so this way the tweeter and woofer was at a slightly different location by a few inches) But I'll definitely give your suggestion a try today and see what happens. Maybe even try some vastly different positions just to see if it helps or not.

[Deleted User]

It's possible the two T15 are connected "out of phase" with each other thereby cancelling bass frequencies.

Emlyn

Audyssey can check for phase during the initial setup, but it's known to not catch everything or report incorrectly because of room interactions. The placement inside a cabinet can affect that. Definitely worth checking the connections again. What Ken is saying is double check to make sure the receiver outputs and speaker inputs are hooked up properly. Red to red (positive) and black to black (negative). And left outputs to left speaker right outputs to right speaker.

I would make the system work where it's currently located rather than trying to move things around. You can also take the subwoofer out of the equation temporarily and set speaker levels and distances for the T15s and center manually using a sound level meter and select no subwoofer in the receiver. Or for a test you can even do it by ear.

You can get an app on a smart phone if you don't have a dedicated SPL meter. Try just listening to the T15s in stereo "Pure Direct" mode, which eliminates processing, to see how they sound. If you have done all that and still no apparent bass from the T15s, there may be something broke somewhere. A hard reset of the receiver to factory defaults can remove speaker settings. The manual will say how to do that.

What's curious is the PSW110 has an upper frequency reproduction of around 250Hz. With the T15s set to cross over at that frequency, you would have almost no bass coming from the T15s.

Lapparty

So, I've experimented quite a bit again. Here's what I've found:
After changing the wires thus changing the phase audyssey immediately warned me that the speaker in question is out of phase and during the test I couldn't hear any difference in the test tone either, it was still pretty flat sounding (even on it's own so it's not like the other speaker is killing it).

I've also tried different locations, using the speakers upright, bringing them closer to the wall, further from the wall, etc. In the end I've put the left speaker on a bookshelf next to the screen and oh I could definetely hear a difference. As if the speaker's heart just started beating. Didn't even need the calibration to finish it was so audible. Especially compared to the FR speaker which was left in place. They are definitely canceling themselves somehow or just the bass is not doing it's thing at those locations. The bookself in question looks something like this (I'm a terrible drawer, sorry)


It has a reflecting surface from the left, top and bottom. The speaker also had books behind it.

The problem is that I can't find any place for the FR speaker where it would work like the FL on that bookself. I've tried to nail the FR on the wall at the same height but it was still flat sounding. There's a huge window to the right of the subwoofer so I can't even make a bookself like that on that wall. Maybe some kind of enclosure could work.... But is it really what this speaker needs? I've tried to move the FR speaker everywhere I could, still nothing. Why this bookself seems to be the only place to work in this room I really have no idea.

Lapparty

Hmm. I've found a manual EQ setting in the setup menu of the receiver. Apparently I can set the EQ to some extent. When I copied the "Audyssey flat" curve to the manual setup I've noticed that the front left has -18.5db at 63hz (-2db at 125hz) and the front right has only -2db at 63hz. Could this mean that the problematic speaker is the FL? But to my ears the FR is just as bad as the FL during the setup. tbh I didn't go through with the full setup when I placed the speaker to the bookself as I was too fed up with the sound already. I might have to go through it again tomorrow and see what it says with only the left one on the bookself.

Btw the impedence is set to 6ohms on the receiver as the two surrounds and the ceiling speakers are rated at 6 and the Polk CSM is actually rated at 4. Not sure if it should have any effect on the response curve but I'll throw it out there in case it does.

F1nut

Speaker stands.

Lapparty

update: I moved the left speaker to the bookshelf and did a full calibration. The result is 110hz crossover for the fronts. Unfortunately there's definitely some kind of cancellation happening in that left corner.

Interestingly when I moved the speaker back in place and did a full test again the receiver set the crossover to 150hz. No idea what has changed since yesterday though... The other speakers are pretty consistent (surr. & ceiling 120hz, center 40hz).

Truth is I'm not that happy with 110 either for the fronts. Especially that they even need to be placed to an unconvinient place to reach this. I would like to leave the speakers on the cabinet tbh. Do you have any suggestions for some room treatment that could work? It's probably the bookselfs, the big gap behind the speaker plus the corner that's creating a null. Would that help if I placed something behind the speaker on the cabinet?



Some kind of bass trap behind the left speaker. Or a reflecting surface made out of wood that could prevent the bass entering that corner (at least to 80hz or someting).