Improving Polk TSI 500

[operaman]

I've read some reviews, which I tend to agree with, that the TSI500 midrange is slightly muddied and flat.
I bought my TSI500 pair for $1000 2yrs ago, and have never been completely satisfied with the sound.

As a test:
I introduced a 12" woofer and 3 way crossover from another system .
Removed the bi-amp jumper.
Temporarily wired the external 3-way crossover to:
12" Woofer hi-cross @ 800Hz
TSI tweeter lo-cross @ 5000Hz
4 - 6 1/2" TSI drivers crossed @ 800 & 5000Hz

If my thinking is correct, leaving the original TSI500 crossover in place at its 2500(?)Hz, this should give me:
2 - 6 1/2" drivers operating from 800 to 2500Hz
2 - 6 1/2" drivers operating from 2500 to 5000Hz

The experiment seemed successful:
tweeter more brilliant
6 1/2" speakers more distinct
base sharper

My question is where do I go from here:
If I cut a hole and mount a 12" woofer to the lower side of the TSI's will the existing porting support the
additional back pressure?
Any suggestion for choosing the woofers and passive 3-ways?

 

[Swerd]

My question is where do I go from here:
If I cut a hole and mount a 12" woofer to the lower side of the TSI's will the existing porting support the additional back pressure?
Any suggestion for choosing the woofers and passive 3-ways?

The likelihood of finding any woofer that works in those Polk cabinets, other than what came with them, is slim to none. The usual way to design a speaker is to find a suitable woofer, and from it's Thiele/Small parameters (published by the maker or measured yourself), determine the volume and dimensions of a cabinet. Finding woofers that work with an existing cabinet is the backwards way of designing a speaker.

You haven't really identified the source of the muddy sounding mid range. Even if you did get lucky and find a woofer that could work in your existing cabinet, you don't know if that would solve your problem, or introduce new problems.

Are your speakers 2-way, 3-way, or 2½-way? It isn't clear from what you described. And I find little useful info about them online. I think you'd be better off looking for new speakers, or building a DIY speaker already designed and tested by someone experienced.

 

[j_garcia]

Replacing the speaker completely is the best method of improvement.

You've got the x-over points, but what about the slopes? The network compensation for the various drivers interaction between each other including the additional woofer? Since the replacement x-over was designed for different drivers, likely that alone could be responsible for the difference in sound, but that does not necessarily mean good things actually happened response wise. You hear the difference and it seems to sound better to you, though that may be because new ranges are emphasized, where before they were being controlled for smoother response. Putting arbitrary x-over points with these drivers without knowing what the response of the drivers is, is pretty much guesswork.

 

[jonnythan]

There's a lot to loudspeaker design besides the driver selection. Dropping a new driver or drivers into an existing crossover/enclosure is definitely not the way to go.

Replace them entirely, or be prepared to get neck-deep into enclosure and crossover design.

 

[BoredSysAdmin]

Replacing the speaker completely is the best method of improvement.

That, +1000

 

[Latent]

One other trick to try is get a SUB and set your front speakers back up as normal and set them to small size in your AVR. Now listen to some music and change the crossover frequency in your AVR to set which level the base frequency gets sent to the sub instead of output by the speakers. As you adjust it up as high as it can go (normally around 240hz) it will reduce the low frequency load on the speakers and see if you notice the same improvement you had with your external crossover setup. Setting the crossover this high may sound better but it's not an ideal solution as bass frequencies from 100hz up to 240hz may start sounding like they are coming from the direction of the sub instead of the main speakers and this may force you to place the sub very close to your speakers and lose some of your left/right sound stage. But anyway it is a good test to see if is some design flaws in these speakers not producing bass and mid frequencies at the same time well.

Also if you previously had no sub at all or had the speakers set to Large in your AVR then you may find setting them small and trying a more sensible 80-100hz crossover may help your speakers shine a bit better.