FXi30 wiring for 6.1

stanman

Hi everyone.

This is my first posting on the clubpolk forum. First off, I'd like to say that I've read through quite a few of these threads and found most of the info here pretty useful. Thanks!

I'm about to receive a pair of FXi30's from Crutchfield to (almost) complete my 6.1 setup. $230 incl shipping, after 1st purchase discount of $20). I'm planning on using the new speakers on the same surroun back channel by wiring in series (to maintain an impedance above 8 ohms), and running them as bipoles about 8-10ft apart. Does anyone have any experience with this and/or know of any implications?

My setup is as follows:
- Yamaha HTR-5650 receiver
- RTi-8's bi-wired, but through the A/B-channel, not separate amp (seems to work and sound pretty good)
- CSi-3 in front
- R15's as R/L surround
- Altec Lansing dual 6.5" sub that will be replaced soon!

And before anyone jumps on this, I've considered putting the FXi30's as side surrounds and R15's in back, but I really don't have any space behind the couch, no walls to mount on the sides, and I intend on using the setup for 5.1 music sources like SACD in the very near future. BTW, if you haven't seen this yet, there's is an interesting article re: speaker configuration:
http://www.hometheatermag.com/loudspeakers/25/

Frank Z

Welcome!
I'd caution against wiring your speakers in series. Basic electronics...never wire loads in series. Any chance you could keep the FX's for the surround channels and suspend another Csi3 from the ceiling?

Regarding your speaker wiring, looks like you are attempting to bi-amp not biwire. I would stick to standard connection , or even bi-wiring if you feel it makes a difference. Your receiver is rated at 80 wpc through the "A" speaker output but the output may in fact drop to 40wpc when both A & B are selected. This is generally the case with most if not all receivers.

disneyjoe7

Frank,

Just some points here, could be wrong but hear me out.

Wiring in series Never? Why when a speaker maybe 8ohms wired in series - / + to -/+ would be 16ohms this sould be cool for an AVR right? The sound maybe hard to adjust/ level out but maybe worth the try.

A/B speaker output used again why not. 8ohm speaker to "A" input, 8ohm speaker to "B" input = 4ohms to receiver some AVR wouldn't like but if it works for hime ok. It maybe better for him do to the fact he is forcing AVR to deliever more Watts.

Could be some Newbie input here, so anyone needs to set me straight go for it. :eek:

Originally posted by Frank Z
Welcome!
I'd caution against wiring your speakers in series. Basic electronics...never wire loads in series. Any chance you could keep the FX's for the surround channels and suspend another Csi3 from the ceiling?

Regarding your speaker wiring, looks like you are attempting to bi-amp not biwire. I would stick to standard connection , or even bi-wiring if you feel it makes a difference. Your receiver is rated at 80 wpc through the "A" speaker output but the output may in fact drop to 40wpc when both A & B are selected. This is generally the case with most if not all receivers.

stanman

Heh, you guys are pretty quick with the replies. Thanks!

From my limited knowledge of electronics, resistance of loads wired in series is calculated as RT = R1 + R2 + ..., which should place the total impedance of two series-wired FXi30's at 16 ohms. I did place a couple of tech support calls, one to Yamaha and one to Crutchfiled (both of whom were quite helpful, btw). The Yamaha guy said it would be fine to wire in series (and definitely not in parallel, because it reduces total impedance to unacceptable levels for the amp), but mentioned that I might hear some degradation in sound quality due to the raised impedance? From my understanding, there shouldn't be any reduction in sound quality from the speakers if they are identical, but that sound levels would probably need to be adjusted. Can someone verify or correct me on this?

I've thought about using another CSi3 as rear center, but logically-speaking, the front and rear center channels are passing through very different parts of 6.1 mix. The front center is putting out, what was it again? 70 - 80% of the sounds in the front-stage, and almost all of the dialogue? I suppose that's why there are so often 2 identical woofers in the same cabinet. Suspending in the ceiling is probably an option I don't really want to consider, especially since I already have the FXi's ordered!

I will likely try re-wiring the RTi8's again and do a more in-depth test. So far, I've only done a short (15min) test with one speaker running single wire and the other bi-amped/wired... (I can't figure out which terminology to use, since it's running off the same amp but diff. channels, but there are 2 sets of wires running to each amp. )
dj7, can you pls clarify the 8ohm vs. 4ohm load to the amp? I'd thought that since they were wired on separate amp channels they would both be 8? Maybe I'm starting to make too many assumptions... in any case, I'll give it a try the other way again, using output A only with those contact connectors in, and see if I really see much difference.

I'm probably going to have to do quite a bit of readjustment on sound levels if I do try to wire the new ones in series. I've got myself wondering why I'm bothering with all this, considering there's only a handful of DD EX or DTS-ES encoded movies out there.

Frank Z

I would have to say it's more a matter of being able to properly calibrate the system for the best possible performance. Wiring in series will create a 16ohm impedance, yet the remaining channels will be driving an 8 ohm load. 1 channel is going to have to work a lot harder to drive the speakers that are wired in series. The Yamaha receiver can be used to power speakers that are rated up to 16 ohms, but the ability to do so is not assignable to the individual channels, rather it is a global setting. All or nothing so to speak. Although the results of wiring a couple of speakers may not affect the audio quality a great deal, one has to wonder if the increased demand placed on the affected amp will cause the receiver to go into a shut down/protect mode prematurely, assuming that the receiver is configured to drive the speakers that are rated at 8 ohms.

IMHO...Since the receiver is rated to power up to 6 channels, it seems more prudent to use the designed capabilities of the receiver to fullest extent possible instead of re-inventing the wheel to add a 6th speaker. System calibration will be much easier, the surround effects will sound the way they are supposed to. I think that the performance of any DSP/DPL modes would also suffer as a result of the current configuration.

Does this make any sense?

gatemplin

Originally posted by Frank Z

Basic electronics...never wire loads in series.

Lots of speakers use two 4 Ohm midranges wired in series. Especially in MTM configs.

I doubt it will go into shutdown mode. 16 Ohms will draw less current than lower impedance speakers. You should be able to increase the gain to that channel in the AVR and most receivers are rated for 16 Ohm loads.

gatemplin

Originally posted by disneyjoe7

A/B speaker output used again why not. 8ohm speaker to "A" input, 8ohm speaker to "B" input = 4ohms to receiver some AVR wouldn't like but if it works for hime ok. It maybe better for him do to the fact he is forcing AVR to deliever more Watts.

[/B]

In this case I dont see how it would increase the power sent to the speakers. First, you are not increasing the voltage signal. Second, the amp still sees the same 8 Ohm load. It is basically just bi-wiring as Stanman said.

disneyjoe7

Ok,

So I rethinking this bi-wired to AVR to A & B speaker outputs.

If AVR is designed to handle 8ohm / 6ohm load. Then if the engineer designed this AVR he / she could add a power resistor say 2.4ohm in series with output when 2 speakers are power together. So 8ohm + 8ohm = 4ohms too low for AVR to handle (bad design if not adding resistor in series internal in AVR) so with 2.4ohm added to each speaker leg we get 10.4ohm + 10.4ohm = 5.2 ohms better for amp in AVR.

Also rethinking this (something I wasn't really clear on before either) RT800i speakers like other polks are Bi-wire / Bi-amp able. so are we saying that these input are 8ohm each? Yes I think so, but I didn't take into account that the crossover will have something to do with all this. So lets say this lower is 8ohm at 0 to 500hz or so (guessing ok) the upper 500hz to 26000hz. So amp never sees the 8ohm + 8ohm thing being 4ohm, just the 8ohm from 0hz to 26000hz. (I know RT800i would smoke at 0hz but I do think it would try, I seen mine try something like 15hz or so NOT PRETTY)

So in short Stanman could be losing something wiring speaker as bi-wire A/B speakers. Stanman should try just bi-wiring speakers to A output to compare.

As far as the 16ohm speaker thing give it a try like other tech support said may have to add level to this channel for proper level matching. So front could be 0 center 0 rear 0 rear center +5 just need to confirm with test disk & sound meter.

stanman

disneyjoe7, thanks for the update...

I will be testing the various wiring configurations hopefully some time this week, including bi-wiring, bi-wiring on separate outputs, and single wiring. I just wish I had pre-outs and $$ for another amp.

Just curious, does anyone else have any feedback as to the advantages of bi-wiring vs. using just one set of wires and going through the crossover? Or is that buried somewhere in another thread?

gatemplin

Disney,

"If AVR is designed to handle 8ohm / 6ohm load. Then if the engineer designed this AVR he / she could add a power resistor say 2.4ohm in series with output when 2 speakers are power together. So 8ohm + 8ohm = 4ohms too low for AVR to handle (bad design if not adding resistor in series internal in AVR) so with 2.4ohm added to each speaker leg we get 10.4ohm + 10.4ohm = 5.2 ohms better for amp in AVR. "

The L&R channels are seperate if this is what you mean.

"so are we saying that these input are 8ohm each? Yes I think so"

Yes

"I didn't take into account that the crossover will have something to do with all this. So lets say this lower is 8ohm at 0 to 500hz or so (guessing ok) the upper 500hz to 26000hz. So amp never sees the 8ohm + 8ohm thing being 4ohm, just the 8ohm from 0hz to 26000hz"

Right, but you are looking at this as a DC circuit and the speakers as resistors. Impedance is a combination of resistance, inductance and capacitance so the impedance is always varying with the frequency of the signal. On an 8 Ohm driver impedance can be low, like 5 ohms, and high, like 32 Ohms, depending on the frequency.

disneyjoe7

All understood thanks, I was just trying to simplify a little here.

What I was trying to say was if you looked at the RT800i lower post with an ohm meter you get maybe 5ohms / looking a upper you may get 30 / 40ohms. This changing all the time with different freg in the music.

I comparing this to 2 speakers to 1 amp output. I needed to clear this up in my mind also before. Sorry if I wasn't clear and set someone wrong.



>>Right, but you are looking at this as a DC circuit and the speakers as resistors. Impedance is a combination of resistance, inductance and capacitance so the impedance is always varying with the frequency of the signal. On an 8 Ohm driver impedance can be low, like 5 ohms, and high, like 32 Ohms, depending on the frequency.<<

gatemplin

You can't use an Ohm meter because it only measures DC resistance. But you are right that the impedance is always changing.

disneyjoe7

An meter right now DC measure won't show me that? I understand DC / AC.

disneyjoe7

Ok.

So I found my OHM meter RT800i bottom 4.5ohms (Ok cool) top let's say infiniti.

Given this is DC. Given this will change as freq changes.

Rethinking as above post on bi-wiring A/B output wiring, you must be missing something. Rewire as "A" only, you can wire as Bi-wire that's cool just not the A/B thing.

gatemplin

Remember that impedance and resistance are both opposition to current flow, and they are both measured in Ohms, but they are not the same. You cannot measure impedance with a Ohm meter, only resistance at 0 Hz.

disneyjoe7

It doesn't surprise me that the RT800i upper has infinite resistance at DC (it must be wired in series with a Cap) the bottom wired in series with a coil. Bottom raises in resistance going up / bottom lowers resistance going down. All this in Audio frequencies.

Do you see my point? I saying don't wire speakers as top / bottom on A/B speaker outputs AVR will add resistance as self protection, killing any benefit you had.

Or I'm I missing your point?


:rolleyes:

gatemplin

Originally posted by disneyjoe7
It doesn't surprise me that the RT800i upper has infinite resistance at DC (it must be wired in series with a Cap) the bottom wired in series with a coil. Bottom raises in resistance going up / bottom lowers resistance going down. All this in Audio frequencies.

Right, it will read OL at the 0 Hz signal from the Ohm meter across a capacitor. One cap in series with a tweeter is a first order crossover, you probably have a 2nd order.

Right, on the woofer the impedance (not resistance), will go up as you increase the frequency, and up before and after the tuning frequency. On the tweeter impedance increases as you go down in frequency (due to capacitive reactance from the caps) and increases on the high end due to inductive reactance from the voice coil.

I dont understand what you mean by
"AVR will add resistance as self protection, killing any benefit you had."

For example, if you take two 8 Ohm speakers, add one to right channel "A" and one to right channel "B", now the amp is seeing 4 Ohms nominal impedance on the Right channel. Two 8 Ohm woofers in parallel, and two 8 Ohm tweeters in parallel. It wont add any resistance, if the speakers are drawing too much current, it will go into protect mode.

The benefit may be no more than using only channel A and bi-wire, but I dont believe it is worse.

gatemplin

Check out this link for more info on speaker impedance and speaker protection. http://sound.westhost.com/impedanc.htm

stanman

Just thought I'd let all of you know that I got the FXi30's set up in series, like I mentioned I was gonna try in the original post. I was surprised that the speaker levels didn't need too much of an adjustment even though the rear center channel is connected to 2 speakers in series. Maybe +1 or +2 db difference?

I've only managed to test a few scenes from a couple 6.1 movies in the collection, and so far everything sounds pretty impressive. I find the bipole setting with the speakers on the rear wall spreads the sound nicely over the whole rear wall, and it sort of sounds like one larger speaker set farther back. I tested a few of the same scenes in different listening positions, and found that the bipole setup is very good for maintaining a good rear soundstage even when the listener is seated to the right or left of center. Does this make sense?

As to the bi-wiring of the RTi-70's, I think I'm going to pick up some banana plugs and make some jumper wires and try running it with a single set of wires from the amp to test it out. Judging from some of your posts in the other thread re: bi-wiring, this seems to work for a lot of you.