LSi Series Modifications

skrol

It seems the LSi series doesn't get much attention these days. Perhaps they will never be legendary as the vintage Monitors, RTA's or SDA's and are now overshadowed and bested by the LSiM, Reserve and Legend series.

We all have read about, and some have performed, modification and upgrades to the LSi series crossovers and sub-woofer replacements with very good results. However, I was wondering about applying other modifications that are popular on the more vintage speakers. It seems that they would have benefit but I haven't read of anyone doing so. We could also include other more modern Polk Audio lines too. Some of these mods may include:

• Damping the speaker baskets with Dynamat
• I assume JB Welding the magnets is no longer necessary. On MW65xx it did seem to further dampen the basket ringing if a little is placed between the magnet plate and the basket. Perhaps provides a little stiffening of the motor assembly too.
• Adding a square of BH5 inside the cabinets on the back wall behind the drivers to absorb the back wave. I realize adding more damping could impact the tuning more in such small cabinets.
• Sealing cabinet.. Ok, they are ported but what about that gaping hole on the LSi15 (and probably LSi25) where the wires feed through from the lower section to the upper (WM and tweeter) section? I stuck a little Moretite in the hole to seal my LSi15's.
• Damping the port tube(s) to reduce its physical vibration
• The now infamous placing foam inside the speaker baskets to damp reflections from basket itself (controversial as it is)
• Other?

Anyone tried any of this or other mods? Results?

ChrisD06

Rebuild the crossovers. I wouldn't seal any holes left from factory as I'd trust that Polk knows what they're doing with cabinet design.

xschop

I'd brace the cabinets on those side to side if they aren't already. Just because the drivers are stronger cast alloy, doesn't mean they cannot ring, Dynamat wouldn't hurt too be applied. I believe Trey mentioned the cast baskets are weak. To me that's crap casting technique.
Not sure if there is enough surface area on the frame spokes to warrant frame foaming on those to mitigate reflections (your call).

Edit, just looking at LSi9 driver pics, they'd benefit from inner frame foam application as well. JM 2C

VR3

Lsim had weak baskets

The lsi series has 1.5 inch thick side walls, pretty robust

xschop

VR3 wrote: »

Lsim had weak baskets

The lsi series has 1.5 inch thick side walls, pretty robust

Thank you for clearing that up. Makes sense as they went to smaller/thinner frames to achieve more performance to include reflections mitigation.

Just looking at those LSi driver pics and they look choked-off. I'd be on my grind and doing foam lol

Gardenstater

Is this what the drivers look like? In the interest of accuracy the foam in the basket mod is only "controversial" (infamous??) amongst those who have not done it and have not heard it.

F1nut

LOL

skrol

VR3 wrote: »

Lsim had weak baskets

The lsi series has 1.5 inch thick side walls, pretty robust

I recall seeing a bunch of LSiM on ebay a while back that had been damaged and fractured (destroyed) woofer baskets. Pretty horrifying to see.

skrol

Perhaps I'll try some of the tried and true mods that have been used on the vintage monitors. I would like to do xo mods at least on my LSi7 that I enjoy the most (in my home office). I always ponder if I want to keep the LSi15 so not sure I want to spend the money or effort on them.

Hansvelton

Gardenstater wrote: »

Is this what the drivers look like? In the interest of accuracy the foam in the basket mod is only "controversial" (infamous??) amongst those who have not done it and have not heard it.

To my knowledge, and I have read a lot about ALL Polks, there is no such mod for the Lsi....

Foam in a basket,, @F1nut maybe you can chime in. I see you Lol'ed this post, give us more!

xschop

skrol wrote: »

Perhaps I'll try some of the tried and true mods that have been used on the vintage monitors. I would like to do xo mods at least on my LSi7 that I enjoy the most (in my home office). I always ponder if I want to keep the LSi15 so not sure I want to spend the money or effort on them.

Why don't you mod up the 7's so you'll have a good idea what the sound signature of your 15's would be?

ExJAck19

VR3 wrote: »

Lsim had weak baskets

The lsi series has 1.5 inch thick side walls, pretty robust

I can’t speak for all of the lineup, but my old LSi7s were a thinner box with the Ebony sides that were double-sided taped on. I desided them with a butter knife since they were used as surround backs in conjunction with LSiFXs for side surrounds

D_M2

Been a longtime lurker in the old days. The LSis have been my cup of tea, so I never moved on to another speaker. Early this week, my left front LSi 25 developed a loud obnoxious noise. I suspect the plate amp is dead. Has anyone successfully made the LSi 25s passive? I've seen the electronetix repair ad on ebay, but if someone has successfully made them passive, that might be the better route. I do have LSi15s, I just forgot to hoard an extra set of LSi 25s.

mantis

I never modified mine, I sold them before that craze got popular and missed out on what you guys got to do, have fun and improve on a already very good line of speakers.

I think the LSI line was a damn good line even un modified. The LSI 15's where pretty damn good when properly setup, set to small, 80hz placed in the room well with good amp power.

The LSI9's however to me where flawed, this is a speaker I would want to modify IF I still owned them. They had a good sound but the bass was always to strong and made the speaker sound un balanced.

The LSI7 was damn near a perfect speaker at it's price point. Well balanced , excellent overall sound quality and they required less power to sound wonderful.

The LSIC I thought was great, well balanced and very similar to the performance of the LSI7. I remember people complaining about the LSIC back when they where still talked about alot in here but I never found short comings of that center channel speaker.

The LSIF/X I thought where a decent surround speaker, at their time basically a outdated design as this was no longer the desired design for Dolby Digital and DTS. But if you have multiple seats and only one pair of surrounds, they worked very well to give everyone a good surround experience IF placed properly.
What I use to do with there was place them behind the first row and just slightly in front of the 2nd row. Not exactly the place you would think would be ideal but with the Dipolar design , even in Bipolar mode , the 2nd row got a good surround experience and the 1st row got a excellent surround experience.

The LSI25 was a very under rated speaker. Back when the LSI line came out, I personally was very tired of powered towers. So I completely overlooked this model. BUT Once I started installing them, I noticed they where MUCH better sounding then the LSI 15 in every way. So your thinking it's the added and controlled bass, well your on the right track but they must have had different crossover points as the mid bass on the 25's was more pronounced and smooth. They didn't have bloated bass like the 15 and 9 models did. They where incredibly smooth and really the star of the line next to the LSI7. I set these speakers up as I do most in small 80hz. What most people miss is how much the room influences bass response and when you have the ability to move a pair of subwoofer around the room to find the best placement, everything sound related gets better.

If I came across a clean well taken care pair of LSI7's , I would grab them. Cherry or ash finish.

D_M2

Mantis,

Thanks for the refresher. Your experience has always been mine as well with the LSi series. From the beginning, I've heeded the advice of some of the knowledgeable polkies. I never had a set of 9s, but I've always run my LSis with an amplifier and the ability to set the sound level with a test tone. Prime example, I grab my 15s and stick them in without calibrating the sound level. I play one of my favorite songs where you feel the music, not just hear it. I'm absolutely gutted, walking around the house looking at my torn apart 25s muttering, it was a good run. Then the light bulb goes off, you have forgotten how you found contentment son!

I go grab my analog RadioShack sound level meter and adjust the 15s. Guess what, LSI contentment is still alive and well. I'm probably missing a little bit, but the smile is back on my face. I found the recipe that works for me years ago by pairing LSis with Denon Amps and Preamps. Skrol, apologies for mucking up your thread. I wasn't sure where to ask about a possible LSi 25 conversion.