RTI12 Crossover
Nanometer
Posts: 7
I was curious if anyone knew where I could find a diagram of the crossover in the RTi12 speakers? Or perhaps where an identical diagram would be online... don't need the correct values, just something where I could actually follow. The goal is to change the crossover frequencies.... Thanks!
Post edited by Nanometer on
Comments
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Basically, I'm trying to send more frequency range to the woofers, and less of the range to the mid speakers. I'm also considering raising the crossover frequency for the tweeter so it doesn't play the lower end of the frequency(1,800 Hz)
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There's a good chance you'll introduce audible distortion by raising the woofer's x-over frequency. I wouldn't be surprised if lose some imaging too."He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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The issue is that the crossover frequency is set to 120Hz(Woofer to Mid), which is definitely into the subwoofer range(which it isn't). I'm talking about raising it to about 300Hz to 500Hz.
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That doesn't sound like a good idea at all. What does the RTI12 use, 5" mids? They should have no problem playing down to 120hz.
How do you intend to change the stock crossover values? Good luck using online crossover calculators, they're wrong 90%+ of the time."He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche -
but the rti12 also has 3 7" woofers to assist the rest of them, Forcing those speakers to only play 120 Hz and lower isn't really doing much sound wise. The idea is that the woofers will play 20-400Hz, the mid will play 400 to 2,000Hz and the tweeter does 2,000Hz to 23,000Hz.
You really don't need a complex calculator to figure out the values, one of the nice things about crossovers (2nd order in this case) is that each filter is independent from all the other filters. This means that figuring out values are not hard at all. Those stupid calculators make a bunch of assumptions, which many don't even bother to ask. Probably the accuracy you are referring too. though I can't speak for all of those calculators, they all give down the general idea in how the circuit should look. A single filter can be used to verify the values you believe to correct.
It would be a guessing game, but I know which values to increase, and which values to decrease (capacitance and inductance). I could be wasting my time, but I just wanted to get more base out of these towers-- Which happens to be the biggest complaint by many other people who own these speakers. -
If you want more bass, increase the resistance of the HF and MP filters. If you don't have a measurement setup, modeling software or a plethora of passive components on hand, you'll probably do more harm than good."He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche
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I've read that increasing the resistance of the circuits will deliver less power to the speaker, since power output is directly related to the load resistance. I was thinking to lower the Woofers capacitance and inductance(high pass woofer to 400Hz). For the mid range the low pass would need to decrease similar to the woofers(mid filter to 400Hz), and the mid high pass would stay the same(2000Hz).
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This sounds like a terrible idea.
Just my $.02
Good luck.The nirvana inducer-
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Not to rain on your parade, but this sounds like a terrible idea to me, and probably won't result in better sound.
I would have to imagine that Polk had reasons for using the crossover points that they used.
Just my $.02
Good luck.The nirvana inducer-
APC H10 Power Conditioner
Marantz UD5005 universal player
Parasound Halo P5 preamp
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PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
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I think polk tried to make a tower speaker that could substitute a subwoofer. but the idea really is just up in the air, I'm more so leaning on that im not going to even bother...
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Whoops...the second post there was meant to be an edit to my first post.:o
The A9's are never going to take the place of a good subwoofer. They have very respectable bass output on their own, but not on the level of a good sub.
The three 7" woofers can produce some great bass, but they'll never match the output of larger 12-15" woofers. You can work around physics, but you can't defy it. Big bass requires LOTS of air movement.
What you're discussing could even potentially reduce the ultra low end of the speakers, because the 7" woofers would be reproducing a much wider frequency range, and wouldn't be able to produce the low bass as cleanly.
The mid-ranges on the A9's are also easily capable of producing sound down to, and beyond, their crossover point.The nirvana inducer-
APC H10 Power Conditioner
Marantz UD5005 universal player
Parasound Halo P5 preamp
Parasound HCA-1200II power amp
PolkAudio LSi9's/PolkAudio SDA 2A's/PolkAudio Monitor 7A's
Audioquest Speaker Cables and IC's -
yea I agree with you, I just found it so odd, how the crossover frequency is set so low. I've seen lots of setups, but none with a crossover freq set this low. Using a bi-amp, The bass is pretty impressive, but you are very right in that it does need a sub of it's own. right now, it's just 2 10's from klipsch.
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I bought a set of RTI12s two months ago, and have been annoyed by the lack of bass as well.
I have read a few threads at the AVS Forum where some claim that the mids and woofers are out of phase at the cross over frequency (the reason for the dead frequency zone).
Why is the OPs idea a bad one? If he removes the stock crossover and builds a new one (without damaging the original, which he can later reinstall), where is the harm? -
First question I have is, what is your amplification? Second is, how long have you had them? Then, placement, room size, acoustics, cables etc. A7's and A9's are not weak on bass, they are uasually weak on power fed to them and have not been broke in properly.
3 7" woofers will move as just much air as a 12"woofer.
It took a good three months and added power to get mine going.
For anyone powering those with a reciever, good luck finding deep bass.Polk RTi A7's FrontPolk CSi A4 CenterPolk Tsi 100's SurroundOnkyo TX-RZ50:)Oppo BDP 83 (Collecting dust)MIT Terminator 3 Speaker CableMIT Terminator 2 IC's (Oppo 2 chan)Signal Cable HT TWOEpson PowerLite Home Cinema 1080Hisense 55 U8GBelkin PF 60 Power Center -
Basically, +1 on what Ric just said.
In my room at least, I had to pull them quite a way from the wall to tame the bass in my fairly large 22x24x12 room. And even then, I can feel the bass sitting about 10 ft from them while still quite a bit below max db. But I also run 850 wpc into them, and in general, the consensus is that the 12s are fairly power hungry. Given an efficiency of 90 db 1w@1m, this would seem likely to be the case. So, also as Ric said, if you're powering those with a 100-125 wpc (or even a 200 wpc external amp), you aren't going to get the best out of those speakers. Granted, you won't get the extension that you would from a a pair of good 15" or 18" subs, or even a pair of really good 12s, but for what they are, they're pretty good. Or at least that's been my experience.
As far as why the OP's idea is not a good one, designing a xover is not that simple. You have to account for phase and a host of other things. The 12s are capable of outputting pretty decent bass, so the problem more likely lies somewhere else in the system.Turntable: Empire 208
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Not enough bass is almost surely due to inadequate amplification. Also, if an AVR is in the mix, be sure it's in direct mode. If both of these conditions are already being met, you need to get new speakers, because your standards are too high. I've only got the 10s, but the bass is perfect, IMHO. Don't expect these towers to be subwoofers.
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@ OP: sorry to thread-jack, but this side question may add value for others.
I am the first to admit that my setup is not ideal (Onkyo RC-180, no external amplification, speakers up against the wall, etc.). As expected with my arrangement, the bass is a little boomy. I am not dissatisfied with the low frequency bass; only the upper frequency bass.
When I am playing music that I am familiar with, it sounds like some of the upper frequency bass notes are muted. (Is it clear what I am trying to describe?)
The speakers perform well for HT, but are a little unsatisfying when listening to music. I tend to not listen to volumes above -20db (I live in a condo and have a toddler).
I have a CSi5, and that produces these upper bass frequencies as I expect when playing "all channel stereo", so I am not sure what the deal is with my RTi12s.
I am the third owner of these speakers. They look to be unmodified and in good condition. I expect that they are broken in.
My first thought was the crossover frequency was the problem, but the crossover frequency is within 30Hz of the LSi series, and no one really complains about those. However, because of the difference in the impedance, the crossover design is likely different, despite the similar crossover frequency.
At this point, I see a number options: 1) settle for what I have; (2) sell my RTi speakers and get something else; (3) buy an external amp and bi-amp the RTi12s. (4) adapt the LSi crossovers into my RTi series (after rewiring for the proper impedance); (5) remove the crossover for the woofers, install a set of f-mods with a external amp and bi-amp the RTi12s.
For those of you that noticed he frequency response issue that I mention above, and then went with Option 3, did this solve the issue for you?
Any other thoughts?
