RTiA9 Upper/Lower Array questions

Squishy Tia

OK, I like what my Adcom GFA-555II amp has done with these A9s, but I'd like to have more power go to each respective array within the RTiA9 (midbass/tweeter and bass/sub woofers). I've got some questions regarding the specifics of these arrays before I go with a second identical amp for a bi-amp setup.

1) When both arrays are separated (not joined by the gold buss bar between each +/- connector), is each array seen as a 16 ohm load (nominal impedance), seeing as the speaker's rated impedance is 8 ohms? Or are they different in their impedance ratings?

2) Once #1 is answered, would two 200W /channel amps (identical for equal sound levels between arrays) do any harm to the A9? I guess the question here is what are the maximum RMS power handling ratings for each array separately when bi-amped? The combined speaker arrays are rated for a max of 500 watts when joined, but no documentation exists that I can find for each array independently. This matters, as frying the tweeter or blowing a midrange driver is a distinct possibility if 200W is too much juice for the upper array.

The idea here is to enhance the quality of the sound being output by giving each array its own power source. I'm pretty sure the bass drivers especially would love that. Pure Direct mode would probably sound a lot better in a bi-amp config - I just want to make sure I get it right and don't blow my speakers up.

More power is good, but too much of a good thing can be bad.

Toolfan66

unless you like your ears to bleed and your music to sound like **** I don't think you will have to worry about to much of a good thing. Let your ears be the judge and don't put the pedel to the metal.

As far as bi amping I have been wanting to try it but so many say it's not worth the cost. so if you do it to your A9's then I my self would like to hear what you think as I have the A9's as well.

tonyb

The top end uses very little power to begin with,I don't see a reason to bi-amp. If your the type with sticky fingers on the volume knob,you may just blow a tweet or two. If sound quality is what your after and not loudness,I suggest you look at your source componants and cableing.

cnh

If you like Adcom forget bi-amping and go with 2 x GFA-565 mono-blocks...plenty of power for each tower.

+1 on tony's suggestion as well!

cnh

leroyjr1

I've had (2)Adcom 555's bi-amped on my a9's a while back with great results. Just remember the sound isn't going to change but they will sound more dynamic.


Tonyb. 200watts isn't too much for the upper section of the A9's ( 2 mids and tweeter)

zombiemusic

I agree with leroyjr1. The loudness of the speaker may not change that much, but the quality of the sound, lower fuller bass, smoother mids and highs. I bi-amped my monitor 50's with two Harman Kardon Citation Sixteen pushing over 150 watts per amp/channel. So I highly doubt you will cause your speakers damage...Just go slow and see how they react. But my guess is that if bi-amping the little cheep monitors noticably improve the sound the rti A9 should really sing. and as far I know the impedance should remain the same. 8 ohms.

lets us know what you think when you get it done. Those rti A9's are my dream speakers right now other than a really expensive pair of KEF'S or ushers.

Squishy Tia

One last question regarding bi-amping these puppies. Since each section has their own crossover network (the woofer array has two independent crossovers in fact), I shouldn't need to use a custom crossover network outside the system, should I?

And no, I'm not going for loudness. I already can get that with just a single Adcom amp. I prefer clarity over loudness, and having each driver array with its own power source tends to lend more openness to the sound stage than would a bridged setup (as is default for a bi-ampable speaker).

I'm curious as to why the A9's two independent arrays would both be 8 ohms, as when bridged (the equivalent of putting two sets of speakers on the same output channel simultaneously) the entire combined tower array is still 8 ohms. I know when you put two 8 ohm speakers together on the same output channel(s) they become a 4 ohm load as far as the amp is concerned. So why would the A9's driver arrays independently act differently?

Anybody at Polk know the answer to these?

kawizx9r

Just want to say +1 to the cabling/gear comment.

And if you're worried about 'overpowering' your speakers, that's highly unlikely just like Toolforlifefan stated. Your speakers won't see all 200watts unless you push the amp that loud to push out that much power/current. By the time you do that, I don't think you'll care that you blew your speakers cause I doubt you'll have any hearing left anyway.

What does your setup consist of anyway? IC's/receiver/speaker cable/etc.

Squishy Tia

My setup is as follows:

Yamaha HTR-5860 AVR
Polk RTi-A9 x2
Polk DSW MicroPro 4000
Adcom GFA-555 MkII
Speaker Wire: Monster Z-Series cable, 10 foot bi-amp set (given to me by my best friend 10 years ago). Has thicker gauge cable for the bass section (10G I believe) and 12G for the mid/tweeter amp section. I use bananas on the end (currently utilizing the thicker of the two wires).

I've retired my previous Yamaha bookshelf speakers, since they don't match very well to my A9s, even as surrounds, and I'm still looking for a nice deal on the CSiA6 center speaker. Budget at the moment is what limits me to a 2.1 setup as opposed to a 5.1 setup, but my priority is music over movies so I'm going for the best I can do with the A9s first.

Fun tidbit: I'm always amazed that even after I turn off the Adcom, it plays the A9s at regular volume for a full 10 seconds or so before they finally click off. That's some serious power reserve.

Edit: This forum's smiley selection differs from others. Boo.

selkec

I am also considering biamping with 2 Emotiva xpa-3's. But can never get a straight answer. It seems like everyone says something different.

Squishy Tia

I haven't seen much of the actual Polk CS guys lately. Wonder if they've been told to stay off the forums? I'd love the answers regarding the specs for each array in the A9, even if it were via private message in case of not wanting to divulge such things publicly. It'd help me in determining the proper setup for bi-amping without worries.