RTi10 internal Modification to cabinet

coolflyer

based purely on price, i found myself with a new pair of Polk RTi10's...intention is a second zone in my home which will be purely music. After getting them in place it only took a few min to realize that there is something just not right about them...sure they are still tight, and theyll take some time to run as intended...BUT they just didnt sound right...the mid and tweet are way overdone and the upper port (midbass port) is active as hell, and the others are hardly even able to move a piece of tissue...so, for giggles i decided to run them in the bi-wire configuration to satisfy some curiosities...the bass side of this cabinet is right, the crossover point for the woofer/mid section appears to have a proper top end, but my curiosities were quickly confirmed when i spied the mid woofer just pounding away and the upper port blowing like crazy even without the top side of the cabinet powered...this just shouldnt be when i ran only the lower end of the cabinet...

"Wow would POLK build these things in a common cabinet?? no way, cant be!!"...WELL THEY DID!:eek:

as of right now i'm sitting here with the drivers, and crossover pulled from one of the cabinets to think things thru...but im at a loss as i dont have all of the things which are critical to modifying the cabinet PROPERLY...i dont have the T/S specs for any of the drivers which they have used in the RTi10, which is critical for getting port diameters right...

heres where i need help...if anyone has the t/s parameters for the mid-bass driver RD7217 i could sure use them.
OR
am i re-inventing the wheel here on a topic, or better yet, a solution which has already been discussed?? (i looked but cant find anything)

i do understand that this is more of a HT speaker, but my VM30's are doing a great job in that role, and im a tinkering kind of fellow when it comes to these things, id love to try my hand a solution if there is one...

anyone else with thoughts or observations to this topic that might provide some ideas...im alllll ears.

mdaudioguy

Read through this entire thread and see what you come up with... gets into the issues you bring up about midway through page 3... If you reach a conclusion and can sum it up in layman's terms, let em know.

BigA524

you missed the link to thread md

bass is the weak link to the speakers unless there in a 10x10 room imo.

coolflyer

BigA...you may well be right, and im reading that in other sections here and in other net locations...but im half thinking that it could be a result of the silly cabinet build...a properly sealed and ported cabinet will perform alot better than this would, even on the bass end of the box...im sure of it.

hopefully mdaudioguy comes back with the missing link...my curiousity is peaked

BigA524

He is probably talking about this thread..maybe?

http://www.polkaudio.com/forums/showthread.php?t=111428

coolflyer

yeah, i spied that a day or so ago...i gather they aren't so sold on the low end...but in the same breath, theres no talk of the cause, just the biwire option discussed which will only accentuate the problem of interaction with the midbass driver...the poor thing is being overdriven by the 7" bottom end...and naturally it would be...

...i will see where this goes tomorrow and probably take the evening to make some changes to one cabinet and see where it takes these things...its only a table saw, some MDF and a bit of PL400 glue to make the change...the one worry i have is the port tuning...its not as simple as just trimming till its right...hmmm, or is it...LOL...lets see where this thread goes over the next day and then i'll jump in, educated or not.

dorokusai

coolflyer wrote: »

if anyone has the t/s parameters for the mid-bass driver RD7217 i could sure use them.
OR
am i re-inventing the wheel here on a topic, or better yet, a solution which has already been discussed?? (i looked but cant find anything)

I have those parameters but they're proprietary and since you seem pretty hell bent on redesigning them because you perceive something is wrong...they don't really matter anyways. It's not a perfect loudspeaker and I'm sure Polk knows this as well, what an amazing observation.

That speaker was conceptualized, designed, tweaked and subsequently manufactured to cover a specific set of parameters to include cost point, adjacent model line interaction, driver compliment, cabinet structure, diffraction issues and 100's of other things that Polk engineers spent a couple years to figure out the eventual model. All of those theroetical ideas gain or lose weight and importance throughout the building of any loudspeaker because a team is usually involved....and even more "things". It's a loudspeaker manufacturer after-all, not a white van company or someone with a crazy monkey as a logo.

If a banana stuffed in the port tube was the one thing no one ever thought of, and it brought the loudspeaker into the 10k category or competition....would you still do it....knowing its a banana?

coolflyer

yes...but id rethink the banana approach...:)...and so would you if it brought it into a 10k category of sound quality...

maybe you should re-read my first post...and maybe your own with the thoughts of cost point, structure, and most importantly the diffraction issues you yourself bring up...

im looking for assistance here, not criticism...however i do thank you for your time.

...anyone else with valuable input??

mdaudioguy

BigA524 wrote: »

He is probably talking about this thread..maybe?

http://www.polkaudio.com/forums/showthread.php?t=111428

Oops! :redface:
Yeah, that's the one...

dorokusai

coolflyer wrote: »

yes...but id rethink the banana approach...:)...and so would you if it brought it into a 10k category of sound quality...

maybe you should re-read my first post...and maybe your own with the thoughts of cost point, structure, and most importantly the diffraction issues you yourself bring up...

im looking for assistance here, not criticism...however i do thank you for your time.

...anyone else with valuable input??

Clearly, you're far too serious and intense for any kind of brevity or light hearted wordplay. Good luck and I'll never bother you with anything ever again.

coolflyer

i guess you missed the smile and the humor in my reply...

...i just didnt see the benefit of your input...to say you had the parameters i hoped to gather in an effort to do my damage properly...

truly no ill intent here...im just hoping to satisfy both my ears with a little effort...and my curiosity in the same way...

...if you can come on, post that you arent willing to share, then what can i do.

if i missed something...i do apologize.

i hoped that someone could assist...its that simple...i know its a low value speaker in the overall scheme of things...but it wouldnt be the first time some minor work ended in a valuable increase in quality, im sure you can agree with me there...sometimes a strong base such as the RTi10 can be better in the end from ideas and discussions like these.

i do not mean to come off as missing your humor...but my first post starts with the facts...i came in at price alone, i expect a HT speaker to have a different approach than a true music build...but again, i hoped for some input and help here...

VXR8

I have both the RTi10's and now the LSi9's. These speakers are worlds apart and obviously are designed that way, but if you give your RTi10's sufficient power to drive them, they become an entirely different animal. The bass is beefier and punchier given sufficient power - usually only provided by separate amplification. Not sure what you are driving them with, but a traditional AVR just doesn't bring out their best, on its own.

avphile

How much power are you talking about? I have Pioneer Elite 84tXsi powering Rti-10. Then I added Sunfire TGA5200. The sound improvement was minimal.

bmor

Coolflyer...I don't have any info on drivers for you but am interested in where you go with this. A while ago I hooked up the LF drivers only, as you did, and was puzzled by the effect on the mid and tweet as you found. Some photos of the cabinet interior would be interesting to see. Coming from a design background myself, I find it's sometimes easier to modify something if you know what the original design intent was. Too bad that info may not be available.

VXR8

avphile wrote: »

How much power are you talking about? I have Pioneer Elite 84tXsi powering Rti-10. Then I added Sunfire TGA5200. The sound improvement was minimal.

I currently have 300 watts per channel driving these speakers - the same as they are rated at. Their current connection is also standard and not bi-wired or bi-amped (jumpers still on).

bpbcataville

Holy thread revival Batman!

I know this one is really old but as someone who just picked them up 2nd hand I too was dumbstruck to find there're a common cabinet.

That means it's 3 driver & 3 ports in the cabinet, the large & small front port & power port in the back.
I'm not a designer (obviously) but the calculation on that just seems too variable to be worthwhile vs separating the 7" drivers.

There's some 1x1 along the cabinet just below the small port/mid-bass.
I can't imagine it would do so much for rigidity, it's as if someone forgot to put the plate in the build specs, or they were saying "here's where you put it"

Anywho, I doubt this went anywhere or anyone remembers as this is so old, but on the chance it did, any findings would be welcome.

Thanks

VR3

A long time ago... I believe we put a 100uf cap in front of the mid of the rtia7 and rti10 with decent success but I can't really remember the particulars or have pictures etc

coolflyer

Email me coolflyer @ iglu. Ca

gp4jesus

@bpbcataville & @coolflyer

So sorry I’m coming to the party so late.

Study my work in the link below or return to the “Recent Discussions” page. Skip down to “Tri-amped RTi A7.” I experienced the same kinda “this can’t be right” frustration.

About 6 years earlier I had a go w/a simple yet easily removable “divider/sandwich” just below the mid port. A bit cheesy but it worked! Haven’t looked back.

https://forum.polkaudio.com/discussion/174880/tri-amped-rti-a7/p1

One day I’ll cut a snug fitting piece of 3/4” MDF, secure w/some screws, caulk and call it a day.

Have fun on your journey! Tony