Enclosing the RTI A7 Upper Midrange

New_World_Man

I recently bought a pair of RTI A7's and for the most part I am happy with them. I pulled one of the lower woofers to poke around inside and noticed the top 6.5" midrage is not isolated with it's own chamber. Has anyone tried to seal the top driver off from the bottom woofers?

skrol

Mmmmm... I understand where you are coming from in that you would like to eliminate the influence that the lower bass drivers have on the mid-range driver. However, that would be a major deviation in the design.

The entire cabinet was tuned as one specific volume. By adding a divider to create an upper chamber, you will create two chambers. The upper chamber volume and port would need to be tuned specifically for the 6.5" driver. Depending on the t/s parameters, it may not even be possible to optimize the new enclosure for that driver. Likewise, the lower chamber, which was tuned for the larger volume, will need to be re-tuned along with the port. Again, it may not be possible to optimize the tuning for the drivers.

Higher end Polks have divided the cabinet into multiple chambers, ie. LSi15, LSi25, LSiM series. The drivers were chosen so that the camber volumes could be optimized.

F1nut

^ THIS ^

New_World_Man

Thank you for your response, but it still does not convince me it's a bad idea to experiment with. If the top driver is swapped out with another one suited toward the resulting enclosure size would that help? I am less concerned with the low end response change as I have a subwoofer doing most of the LF work. The midrange on this speaker seems lacking and when played at high volumes it winds up doing a lot of unnecessary work.

pitdogg2

Well then you're on the verge of frankinpolk. They are voiced towards home theater not 2ch audio. You're going to do all that work to completely change the voicing of the speaker. Why not look for a set of different speakers that have the voice you are looking for?
What are you using to run them? Receiver ? Amp? If your using a receiver then it is likely running out power to power them correctly.

westmassguy

According to the specs: "The 6 1/2-inch midrange driver is housed in its own tuned internal enclosure for increased clarity and lifelike detail". Note the small port directly below the midrange driver.


Upgrading the crossover components could possibly help. Then again, you may just not care for the sound of this particular model.

F1nut

Upgrading the crossovers like I did returns very positive results.

gp4jesus

New_World_Man wrote: »

I recently bought a pair of RTI A7's and for the most part I am happy with them. I pulled one of the lower woofers to poke around inside and noticed the top 6.5" midrage is not isolated with it's own chamber. Has anyone tried to seal the top driver off from the bottom woofers?

You're not losing your marbles. What you see is correct & I'm working on a template to do* just that*.

westmassguy wrote: »

According to the specs: "The 6 1/2-inch midrange driver is housed in its own tuned internal* enclosure* for increased clarity and lifelike detail".

The web site is wrong* - has been since Polk introduced the '7.

westmassguy wrote: »

Note the small port directly below the midrange driver.

So what about the port.

nbrowser wrote: »

Sure the dual 7s aren't separated from each other but the MW is cut off from the bass drivers.

WMG take a closer look after you pull them apart and post pics. Either that or, by some twist of I don't know what, yours are the exception.

ZLTFUL

Another consideration that wasn't mentioned above...what're you powering them with?

The RTiAs really open up with good solid power fed to them. Not an AVR power but a nice 200wpc+ amp. They work with an AVR feeding them...just not up to their potential.

pitdogg2

pitdogg2 wrote: »

What are you using to run them? Receiver ? Amp? If your using a receiver then it is likely running out power to power them correctly.

yep I also asked but still have not heard.

westmassguy

gp4jesus wrote: »

New_World_Man wrote: »

I recently bought a pair of RTI A7's and for the most part I am happy with them. I pulled one of the lower woofers to poke around inside and noticed the top 6.5" midrage is not isolated with it's own chamber. Has anyone tried to seal the top driver off from the bottom woofers?

You're not losing your marbles. What you see is correct & I'm working on a template to do* just that*.

westmassguy wrote: »

According to the specs: "The 6 1/2-inch midrange driver is housed in its own tuned internal* enclosure* for increased clarity and lifelike detail".

The web site is wrong* - has been since Polk introduced the '7.

westmassguy wrote: »

Note the small port directly below the midrange driver.

So what about the port.

nbrowser wrote: »

Sure the dual 7s aren't separated from each other but the MW is cut off from the bass drivers.

WMG take a closer look after you pull them apart and post pics. Either that or, by some twist of I don't know what, yours are the exception.

So what? The port is there for a reason. If his cabinets don't have the internal divider, then it was either left out by accident, or Polk modified the design. If they modified the design, then the upper post serves no purpose. @nbrowser stated his had the divider.

westmassguy

nbrowser wrote: »

I have to retract my statement, after this weekend of tearing mine completely apart to replace the crossovers and all wiring and some poly fill, there are braces but the upper chamber is not separated from the bass drivers. Bad look at first with the filler in there before. Apologies.

Sure, make me look like and idiot now.....

gp4jesus

Nbrowser: I forgive you. I made the same mistake my first time in.

Concerning your re-wire - can you rewire one then listen to modded versus stock? Either way go big or go home. No smaller than 12 on the mids; 10 or a 2X of 12. Not easy I know but worth it. Your "bass" will thank you.

WMG: don't be so hard on yourself.

gp4jesus

It looked like a rib to me. My goal is fashion the divider to fit inside the rib.

pitdogg2

then it makes no sense to have a port there. IMHO... Polk on the fly changes nothing new. wonder if the first gen had the separation there that would make sense since there is a port?

gp4jesus

Touché Derek(!) that's also true for the A4/A6 center speakers.

Somehow I doubt the woofers would miss the port below the mid.

Further I question the mid interacts w/the ports beneath the woofers.

Finally I've tried various amp configurations w/out a sub:
1. Full range
2. Separate amps for top & bottom both w/very high damping factors (1000!)

Nothing at my disposal, short of some kind of HP* filtering, will prevent that mid from bottoming out w/bass-heavy music (e.g. Donald Fagen's "The Nightfly") at high levels.
* active bi-amping ~120-150 hz works great!

I'm certain a divider would prevent those woofers from pushing the mid to its Xmax.

Enjoy Tony

westmassguy

Very disconcerting that Polk would make mention of the tuned enclosure in their marketing material, and have the physical port there. Normally, mids are either enclosed, or have a sealed back to prevent interaction with the low frequency drivers.

pitdogg2

DSkip wrote: »

Not so sure I'd subscribe to that. Look at all the RTiA series speakers. Most of them have that same port, even the bookies that are also rear-ported. It is part of the design and should be there.

I didn't know they also had a rear port on the bookies. Then I suspect they are tuned to two different frequencies.

westmassguy wrote: »

Very disconcerting that Polk would make mention of the tuned enclosure in their marketing material, and have the physical port there. Normally, mids are either enclosed, or have a sealed back to prevent interaction with the low frequency drivers.

Must 100% agree with this. BUT monkey in the details says like the "fluid Coupled" SDA's this is still a "tuned Port Enclosure" just not what we would think of 97% of the time. I like you Dave think it has "its" own sub enclosure inside.

Bob Carver would be proud of this marketing speak

K_M

Polk's literature also says this:

"Dimensions Enclosure Type - Mid-High Array Enclosure -Type ARC port
Dimensions Enclosure Type - Subwoofer Enclosure Type -PowerPort Plus bass venting"


Implying the mid/high drivers are indeed in an enclosure of their own with ARC port, and the sub drivers are in another enclosure with PowerPort venting....

Very odd.

pitdogg2

OMG it's a conspiracy....

gp4jesus

pitdogg2 wrote: »

OMG it's a conspiracy....

???

pitdogg2

I'm just funnun is all

We have 3 different folks with web,media and literature stuff that says the same thing.

pitdogg2

And there you have it lol

ken brydson

nbrowser wrote: »

I once saw a Monitor 7 on a grassy knoll...

I boxes no less...

gp4jesus

Today the planets were in alignment, the moon the right color to allow the next phase of LR mods to include...

pitdogg2 wrote: »

you're on the verge of frankinpolk.

...a divider*! Didn't get to h'cane nuts today but I can do those while watching TV.

New_World_Man wrote: »

...but it still does not convince me it's a bad idea to experiment* with.

Got one speaker done just a little while ago. I will connect, compare, post pics, & 1st impressions tomorrow in an 'A7 thread I started ~5 years ago. I will release a template* for public use pending extensive listening.

New_World_Man wrote: »

...when played at high volumes it winds up doing a lot of unnecessary work.

As I posted earlier, no HP filtering on the mid.

Until later... Tony

jeremymarcinko

The mid range on the A9's and rti12'd are in their own enclosure though. I never thought the 7's were supposed to be.

New_World_Man

I did pull the mid drivers on both speakers to confirm and yes these are not sealed from the bottom drivers. I am definitely going to seal them and add a high pass to the crossover. Sorry I have not replied to this earlier, but thanks to those that can confirm my findings.

gp4jesus

jeremymarcinko wrote: »

I never thought the 7's were supposed to be [separate].

How'd you arrive at that? Web site (incorrectly) unmistakedly says they are.

gp4jesus

New_World_Man wrote: »

I am definitely going to seal them ...

See recent posts on my "Will they soften over time?" thread for pics & ideas.

New_World_Man wrote: »

...and add a high pass... ...[to the mid in the] crossover.

Shop for
1. another amp (or two)
2. an active XO
Scrap the
3. binding posts (see my thread's pics)
4. woofers' LP filters and
5. their crappy wire
Solder up some 10 ga (or bigger) between the BPs & those woofers. Your bass response will thank you. Note: woofers are 4 ohm wired in series.

While you're in there:
1. scrap the mids crappy wire
2. solder up some 10 or 12* ga (no smaller*)
3. for a few $s, replace a cap or 2 to the M & T...
...your speakers' upper half & imaging will thank you.

Do all the above you'll have more output from the same input.

Mount your mids & woofers w/PE's small hurricane nut & 8-32 machine screws for See F1nut's "Fun w/RTi A series speakers" thread.

Tony

pitdogg2

New_World_Man wrote: »

If the top driver is swapped out with another one suited toward the resulting enclosure size would that help?

This is why I made the "frankinpolk" comment it had nothing to do with a divider.

gp4jesus

PD2: I think I FrankenPolk'd one of my '7s. I hope to do same to the other over Thanksgiving.

For more details goto Speakers forum - look for "Triamped RTi A7."