polk ls90 tweaks

Lego1

I have the ls90 speakers and the cs350ls center. I've upgraded the crossover caps. Thinking of what else i can do to improve the clarity on these. Don't get me wrong, they sound amazing, but i keep wanting to try to improve the sound. I've looked inside the ls90s and saw polk placed a small folded sheet of darcon foam behind the drivers. The inside wood walls of the speakers are still bare though. Will lining the walls of the speaker improve clarity and sound quality? I noticed the center channel sounds a bit hollow. I can buy some darcon foam at a craft store for this. I dont want to hurt sound quality though, so if it's not worth it, i wont do it. I've read some users have blocked the rear ports with socks and it increased mid bass clarity. I have a 12 inch sub im using with my system and i have the crossover set at 80hz. Opinions please. Thanks!

stubby

If your room allows it, try experimenting with speaker placement. Since you are running a sub, you could pull them away from the rear wall if you have a bit much mid bass bias. Same goes for corner placement; too close and they can sound muddy.

Also, subtle amounts of tilt can improve clarity as well. Aim the front baffle slightly up into the listening area and see if you notice any improvements. This will help more in 2 channel mode, at least when the center channel is not in use.

Don't know what to tell you about center channel tricks, try the sock idea and see what you think.

stubby

Lego1

The ls90 are about a foot away from the rear wall. Forgot to mention, my front 3 are getting 200wpc from adcom amps. I bought some armacell foam tape and used it as a gasket for the tweeter and driver. I also used it on the driver frame. Will the dynamat help that much on the driver frame? Im just looking for better mid and highs clarity. I was thinking lining the inside walls with some sort of felt or something will help, but dont know if you guys have experimented with it. I know too much foam on the inside could hurt since these are ported. Whats wierd is when i checked the tweeters in the ls90, they were sl6500. I changed them for brand new sl6001. I thought the ls90 originally came with the sl6000. I noticed some people take the magnets off of the driver and put dynamat between the magnet and metal part of the driver. Any of you done this? Thanks for the replies!

Lego1

btw, the tweeter for the ls90 is 38.5 inches from the ground, so its perfect for my listening height.

MrGlobe

I got a pair of concrete slabs at my local hardware store. They're 30"x30"x2" and weigh about 35lbs each. They definitely tightened up the sound of the 90s. It's also nice to be able to place the slabs in approximately the right spot, and then move the speaker around on the slab to get positioning perfect. The slabs were $5 each.

Lego1

So you put the speakers on the slab? Interesting. I was thinking of using dynamat inside the ls90, but when i looked inside, these speakers are braced in 6 different spots! Definitely no need for dynamat. I read some have used sonic barrier behind the drivers. What im trying to use is hardwood floor padding. Its the pad that goes underneath hardwood floor when you lay it down. It is made to absorb sound, and i had extras from when i did my floors. = ] i also bought more darcon, so i will give it a try. Im going to staple the floor padding down on all of the walls inside the speakers then place the darcon behind the tweeter and mid woofers. I'll update the thread to let you guys know. I'm doing one speaker at a time so i can compare them. The ls90s are pretty heavy duty.

MrGlobe

Yeah the speakers are sittings on the slabs. It really helped to decouple the speakers from the floor structure, which cleaned up the sound considerably. I usually leave the slabs in place and swap speakers, just placing the speaker in a slightly different position as needed

Lego1

And your wife is okay with large pieces of cement in your house? So I opened up the ls90 and took all of the stuffing it came with out (two pieces of dacron and two pieces of doormat material). I cut 3x3 squares and using spray adhesive attached them to the rear wall behind the tweeter and drivers. I cut a piece of dacron and attached it to the top of the cabinet, then I attached pieces of dacron to the left wall of the cabinet next to each driver. I took the original two pieces of dacron that came with the speakers, folded them in half and placed them behind the drivers like they were originally. I made sure the bottom of the cabinet including the port had nothing next to it. The speakers sound great to me! Very clear. I was afraid of losing some highs since I put dacron behind the tweeter as well, but the highs are still there and sound great!

When I upgraded the capacitors on my crossover to Dayton, I noticed one of my LS90 is the original revision, while the other is revision 1. I just ordered mills resistors and Jantzen 1.0mH 15 AWG Air Core Inductors to make both of them revision 1.

I also bought some 12uf Dayton capacitors to do the capacitor shunt mod on my Adcom 555. Will report back after all the mods are complete.

So far, I love these speakers!

F1nut

Do not use Dynamat on the cabinet walls, period.

What im trying to use is hardwood floor padding. Its the pad that goes underneath hardwood floor when you lay it down.

I'm speechless.

Lego1

It's not dynamat or anything like it. It is a woven fabric. Kind of like a carpet pad underlayment. It's made for sound dampening. When I cut a 3x3inch square and doubled it up, it is about 0.25 inches thick. I used the 3x3 inch square on the back wall behind each mid driver. Then i added a little more darcon to the inside. If i were to use dynamat, it would only go on the metal spokes of the midwoofers. = ]

Lego1

F1nut, you're right. After listening to the speakers for a while, I took all of the stuffing out of the speakers and replaced it with the 2 sheets of dacron which were originally in them. I like the sound much better.

vc69

Lego1, what kind of improvement did you experience with the crossover upgrade?

ken brydson

vc69 wrote: »

Lego1, what kind of improvement did you experience with the crossover upgrade?

He doesn't have them anymore, I bought them from him . They sound awesome!