RF-83 Bi-wire versus Bi-amp, any improvement? A mod for active filtering and bi-amping?

[etc6849]

I'm new to owning a home theater and Klipsch speakers, but I'm pretty technical minded. I recently purchased an Onkyo 905 which is capable of bi-wiring or bi-amping the main speakers. I also noticed on the back of the RF-83's there are binding posts labeled HF and LF...

Are these binding posts on the RF-83 for bi-wiring only or do they truely take the passive crossover inside the speakers out of circuit? I didn't see a switch to take the cross-over out of circuit, so I'm guessing that I can't bi-amp my RF-83's with the onkyo's active crossovers without modifying the circuit to take the cross-over network completely out of the circuit?

I'm basing this logic on the assumption that the high pass filter and a low pass filters will be seperated when I remove the jumpers between the HF and LF binding posts, but still present in the circuit. A schematic for the RF-83 would be helpful, but I'm assuming it's similar to something like this: http://www.padrick.net/LiveSound/Biwiring/Biwiring.htm

Has anyone removed this passive network completely by adding a switch to the back of the speaker that would bypass the internal crossover completely? I'm thinking with a mod like this you could use these binding posts for active bi-amping with the jumper removed. I'm also hoping the impedance wouldn't be too low in this configuration for my 905, but I don't know without a detailed schematic.

I'll consider bi-wiring my RF-83's, but as an electrical engineer, I am very skeptical of seeing any improvement. However, I see much merit to bi-amping if I can use the Onkyo to do active filtering and get rid of the passive filter inside the RF-83's altogether. I could be wrong about all this, so could someone with more audio experience chime in?

[colterphoto1]

The 'bi-amping' that the Onkyo manual refers to is merely allowing the use of it's extra amp channels to 'double-up' the wattage to the main speakers. In a perfect world this would give double the wattage to this speaker. We all know that modern receivers are pretty much limited by their teensy power supplies, so a modest improvement in wattage would be all that would be gained. There is no reciever that I know of that ACTIVELY splits the frequency bandwidth prior to this bi-amping thus achieving true bi-ampliflication like PA systems would attain.

When you consider that the RF83 is much more efficient than other speakers in your HT setup, you'll have to turn their relative volume levels down anyway, so the extra power really can't do much for your over all sound.

If you really want to properly activley bi-amp your RF83's it would require the use of another component like a Rane AC22 or similar device.

Personally, I'd use a good quality wire and leave this option alone. There are some who swear by using separate very high-priced wire for bi-wiring but I've never heard a good demonstration of this. Experiment if you like or other more technical minded members will be along shortly.

[Colin]

Do a search, two sets of wire worked for me, I bi-wired to my bass bins and liked the slight improvement, passive bi-amping really works for me because my 60-watt solid-state amplifier matches my 6-watt SET amplifier, I love the control that a powerful (meaning wattage doubles when impedance is half) amplifier gives the bass!

[tommyboy]

I had my F2's bi amped for a while. (about 5 weeks) The bass was a little better; enough to notice. But once I bought my Sub 12, the bass from my mains wasn't as important. Plus, I wanted a rear surround. so I un bi amped them, and ran my single rs. With my 2 subs, I don't even notice that they're not bi amped anymore. The highs and mids sound the same as before...........

But, the 83's will easily put out more bass than my F2's, so you may want to "test drive" them bi amped. If you like how it sounds, and don't plan on running rear surrounds, then by all means, bi amp them............

[Jay481985]

the 83's meant to biwire only as there is no other way to bi amp it through the binding posts without going through crossover

Also you might want to get another amp as I have a denon 3805 that claims 120 watts but I there was no bass compared to the hk 3480 stereo receiever that also had a claimed 120 watts. I believe its due to an imperdience dip of 2.8 ohms near 38 hertz or so that kills the denon while the hk power supply could do it. I just now use a crown xti 1000 to the system and problem solved, great bass.

[etc6849]

Thanks. Sad to hear there isn't a way to bypass the cross-over without modifying the speakers... Your bass issue is interesting. Denon makes a quality product, but I'm guessing you have to spend $3000 or more to get a Denon AV receiver that delivers a lot of wattage. The 905 really hasn't given me any issues in this regard, but Onkyo's firmware updates and service are very lacking when compared to Denon's.

The 905 has an ok amplifier with the following specs:

Front L/R	140 W + 140 W (8 ohms, 20 Hz–20 kHz, 0.05%, 2 channels driven, FTC) 170 W + 170 W (8 ohms, 1 kHz, 0.7%, 2 channels driven, FTC) 180 W + 180 W (6 ohms, 1 kHz, 0.1%, 2 channels driven, FTC)
Center	140 W + 140 W (8 ohms, 20 Hz–20 kHz, 0.05%, 2 channels driven, FTC) 170 W + 170 W (8 ohms, 1 kHz, 0.7%, 2 channels driven, FTC) 180 W + 180 W (6 ohms, 1 kHz, 0.1%, 2 channels driven, FTC)
Surround L/R	140 W + 140 W (8 ohms, 20 Hz–20 kHz, 0.05%, 2 channels driven, FTC) 170 W + 170 W (8 ohms, 1 kHz, 0.7%, 2 channels driven, FTC) 180 W + 180 W (6 ohms, 1 kHz, 0.1%, 2 channels driven, FTC)en, FTC) 170 W + 170 W (6 ohms, 1 kHz, 0.1%, 2 channels driven, FTC)
Surround Back L/R	140 W + 140 W (8 ohms, 20 Hz–20 kHz, 0.05%, 2 channels driven, FTC) 170 W + 170 W (8 ohms, 1 kHz, 0.7%, 2 channels driven, FTC) 180 W + 180 W (6 ohms, 1 kHz, 0.1%, 2 channels driven, FTC)
Dynamic Power	400 W (3 ohms, 1 ch) 300 W (4 ohms, 1 ch) 180 W (8 ohms, 1 ch)
THD (Total Harmonic Distortion)	0.05% (Rated power)
Damping Factor	60 (Front, 1 kHz, 8 ohms)
Input Sensitivity and Impedance	200 mV/47 k-ohms (Line) 2.5 mV/47 k-ohms (Phono MM)
Output Level and Impedance	200 mV/470 ohms (Rec out)
Phono Overload	70 mV (MM, 1 kHz, 0.5%)
Frequency Response	5 Hz–100 kHz/+1 dB, -3 dB (Direct mode)
Tone Control	±10 dB, 20 Hz (Bass) ±10 dB, 20 kHz (Treble)
Signal-to-Noise Ratio	110 dB (Line, IHF-A)
Speaker Impedance	4 ohms–16 ohms or 6 ohms–16 ohms

the 83's meant to biwire only as there is no other way to bi amp it through the binding posts without going through crossover

Also you might want to get another amp as I have a denon 3805 that claims 120 watts but I there was no bass compared to the hk 3480 stereo receiever that also had a claimed 120 watts. I believe its due to an imperdience dip of 2.8 ohms near 38 hertz or so that kills the denon while the hk power supply could do it. I just now use a crown xti 1000 to the system and problem solved, great bass.

[DrWho]

FWIW Klipsch engineers tend to refer to them as "balancing networks" instead of "crossovers" because the crossovers generally include extra filtering for tailoring the frequency response. In other words, when properly bi-amping, you need to make sure you can also replicate the speaker EQ. As far as biwiring, it only matters if your cable's parasitic capacitance or inductance starts affecting your passband. If you're going to use different wire, then make sure you've got low capacitance for the lows and low inductance for the highs.

[etc6849]

Thanks Dr. Who. This sounds like pretty good advice (depending on the balancing networks impedances, the drivers impedance at my normal listening level and speaker cable that I'm using). I think my fluke meter will measure the reactance, but I think this is kind of tricky as I would think this value is so small that it wouldn't effect the speakers response curve much. However, since not a lot of things are linear in the real world, I'm guessing I need expensive test equipment to give accurate response curves of the speakers and test several cables. Is there a good reasonably priced laptop based calibration tool that can do this?

Also, do you think speaker cable matters a lot? I would think cable can shift a speakers response curve, but can I hear the difference? Right now I'm using some ultra 600 monster cable only because it was cheaper than lamp cord at my local lumber yard (Manards). It appears the monster cable is well made, about 14 gauge cable and the wires are braided too. They were selling 70 feet of the monster cable for $16.

[winchester21]

Here's a scrap of info that may be helpful. I am on the fence about buying a set of RF 83s. I heard a set hooked up to a recently purchased 125 WPC Yamaha reveiver and then through my 250 WPC 7 yr old Carver A753 hooked up to a new Sony 100 WPc receiver used as a processor only with seperate power amp sources. The 250 watt setup was much better with both music and HT particulary at medium and higher volumes. If you can get more power to your Rf83s I think you will be pleased with the results. People can say what they want about the Rf83s as an efficent speaker but the set I listened to sure seemed to love the extra juice. my 2cents worth.

[DrWho]

Thanks Dr. Who.  This sounds like pretty good advice (depending on the balancing networks impedances, the drivers impedance at my normal listening level and speaker cable that I'm using).  I think my fluke meter will measure the reactance, but I think this is kind of tricky as I would think this value is so small that it wouldn't effect the speakers response curve much.  However, since not a lot of things are linear in the real world, I'm guessing I need expensive test equipment to give accurate response curves of the speakers and test several cables.  Is there a good reasonably priced laptop based calibration tool that can do this?

Also, do you think speaker cable matters a lot?  I would think cable can shift a speakers response curve, but can I hear the difference?  Right now I'm using some ultra 600 monster cable only because it was cheaper than lamp cord at my local lumber yard (Manards).  It appears the monster cable is well made, about 14 gauge cable and the wires are braided too.  They were selling 70 feet of the monster cable for $16.

Have you seen the impedance response of a speaker before? It's all over the place, and even moreso when horns are involved. I'm writing from my phone right now (my laptop is tied up for doing sound system measurements right now) so I can't get as detailed as I'd like to right now. Anyways, since you're a fellow EE, I just wanted to throw out the fact that nothing ever behaves like pretty circuit models...and with audio, when you start talking 0.01% distortion levels, it doesn't take much to add to it. Now keep in mind that this is getting incrediclbly tweaky as there are much bigger fish to fry, but I still think it's interesting. The inductors and caps in your passive xover are definitely causing their own distortion. The parasitic of the wire aren't going to be enough to cause distortion in the wire itself, but it can affect how well coupled the driver is to the amp. The damping factor (ratio of load impedance to output impedance) pretty much determines how much electrical force is available to damp cone vibration. Tweeters usually have overdamped suspensions so it's not as critical, but the imductance of the cable can get high enough to roll off the highs a bit. Woofers are generally underdamped so the extra capacitance increases the output impedance that the speaker sees (resulting in bass that will ring a bit longer). It should follow that the ESR and DCR in your passive xover components will be way worse, which is why I'm a huge fan of biamping (it makes the wire the only limiting factor, which isn't that big of a deal). Btw, you don't need to spend money to get overkill wire - in fact, straight up Belden 16ga should be acceptable for most all applications. Btw, if you check the link in my sig, you can get a glimpse into some of the free measurement programs available...and knowing how they work, you can do a lot more than you mght think. All you need is a computer and a full duplex sound card (and prefeably a quality one if you want to get accurate distortion measurements)

[etc6849]

Thanks Dr. Who. It looks like I can get all the needed items for my laptop from my local guitar center. I'm looking at the following:

Shure C50J microphone cable ($18.99), Behringer ECM8000 microphone ($49.99) and TASCAM US-144 Audio USB MIDI interface ($149).

I'm by no means an audio professional, I'm a power systems engineer, so please feel free to comment on these choices. I'm assuming the US-144 is supported by most of the free audio calibration programs? For compatibility, would you consider the e-mu 0404 over the tascam US-144? I plan on using an XP based laptop. I think the free room EQ wizard program looks interesting as I'm interested in acoustic treatments and subwoofer placememt. I also was going to buy a sound level meter anyways to set input, volume reference, and speaker levels. I'm guessing Room EQ wizard will do this for free and much more accurately than a $70 meter, but don't I need a good sound level meter to initially set the reference in Room EQ?

http://www.hometheatershack.com/roomeq/wizardhelp/help_en-GB/html/index.html

[DrWho]

I just purchased the Tascam and am perfectly satisifed with it. I'm not familiar with the EMU, but that's not to say it won't work. I was actually suprised that the Tascam came in a brushed aluminum enclosure and all the knobs and connectors feel solid (I was expecting cheap crap for $150). I'm running XP on a Dell Laptop. When I get the loopthrough gain structure optimized, I'll measure worst case .015% THD through the unit...much better than my previous MAudio solution (0.05%). As far as absolute SPL, it's really quite meaningless. I never calibrate the SPL in REW or any measurement program unless I'm trying to quantify power compression or something like that. But even then, a relative measurement is usually sufficient. Also, I never set speaker levels with an SPL meter - it's frequency response isn't flat and it isn't very omnidirectional either...doing it by ear is usually best. Besides, a relative measurement is just as good - "reference levels" are meaningless to me because you're just going to turn the volume knob to a comfortable level anyway (which is what the reference level is trying to quantify in the first place).

[etc6849]

I finally just bi-amped (if you want to call it that) my Onkyo 905 and a pair of RF-83's by removing the jumpers. All I can say is the RF-83's sound much better. Even my wife noticed the difference. Check out my post in another thread for more details.

http://forums.klipsch.com/forums/p/86427/1168517.aspx#1168517

[Sick Mother]

etc6849,

I'd be interested to get your (and anyone else's opinion) on bi-amping my RF-83s. I currently have a Parasound Halo A52 putting out 125wpc run by a Denon 3808ci. I have been using the Parasound instead of the Denon for amplification because I believe it does a better job (although I have never done an A/B test on the two). With the possibility of bi-amping the Denon, I am wondering if I will see any noticeable improvments. Will I lose headroom going this route? Are there any other factors I should be considering? I know alot of people would say to hook it up and try it, but before I go through the huge pain it would be, I'm hoping someone with experience will chime in. Thanks.

[etc6849]

From what Dr. Who tells me and common sense, the impedance changes a lot on any speaker depending on the dB level and frequency. To me, this would mean you should use the most powerful amp you have, which I'm guessing is the Parasound, but your equipment is much nicer than mine In Dr. Who's post dated 12-31-2008 10:24 PM mentions he prefers b-amping, and I would say Dr. Who's posts are always very meaningful and he knows what he's talking about. Your situation is different from mine though as you have a choice. I only have a receiver so bi-amping was a no brainer.

I'm really not sure why bi-amping sounds better on my set up other than my receiver couldn't handle the reactive load (impedance) changes of the lower frequency and needed the second amp per channel. You can always give it a try and report back Follow Dr. Who's advice on cabling too and try it out. It shouldn't be more than a few bucks anyways.