Are Klipsch RF-7 II's THX rated?

[StephenM]

but doesn't address the room?

Actually they do. There are THX certified wall materials, doors, etc. Heck, if you've got the cash, you have them build your very own THX Reference theater, certifying the entire room as well as the equipment.

Also, it's worth nothing that one of the big names behind Audyssey is Mr. TH(X) himself.

[Zen Traveler]

Also, it's worth nothing that one of the big names behind Audyssey is Mr. TH(X) himself.

The guy you are referring to is Tom Holman and Klipschsters may find this interesting insofar as THX and Audyssey is concerned: http://www.audioholics.com/reviews/acoustics/audyssey-labs-multeq

"There were two complete 5.1 systems in the room. The powered, 12" three-way amplified Genelecs that Tom always uses for a reference and a second, much lower priced Klipsch system which would be used for the day's demonstration.

...The Klipsch's were a ~$2500 system featuring double 5.25" mid-woofers in the two-way center channel speaker. Klipsch's ubiquitous Tractrix horn tweeter was between the two mid-woofers. This speaker was mounted horizontally on a 48" stand in front of us so that it could fire just over the A/V mixing console that dominated the center of the room in front of the listening position. The left and right speakers appeared to be the same models as the center except that they were mounted vertically on somewhat shorter stands. The surrounds were 5.25" two-way dipole designs with an approximate 90 degree included angle on their opposing faces. They too were mounted on stands. We three were standing a bit back from the console, almost on a plane with the rear speakers when listening."

[gagelle]

That's interesting, Jay. I had a low end Denon multimedia receiver that was fine with my tiny klipsch speakers but as soon as I hooked up my Epic CF-3s, the sound was terrible. A switch to a higher end HK multimedia was a little better but didn't really drive the speakers the way my old HK 2 channel receiver used to. I finally solved the situation by adding a 3 channel Emotiva 200 watt amplifier. I came to the conclusion that most multimedia receivers are not made for big speakers. But I had no idea it was their inability to handle the ohm impediance.

[Jay481985]

That's interesting, Jay. I had a low end Denon multimedia receiver that was fine with my tiny klipsch speakers but as soon as I hooked up my Epic CF-3s, the sound was terrible. A switch to a higher end HK multimedia was a little better but didn't really drive the speakers the way my old HK 2 channel receiver used to. I finally solved the situation by adding a 3 channel Emotiva 200 watt amplifier. I came to the conclusion that most multimedia receivers are not made for big speakers. But I had no idea it was their inability to handle the ohm impediance.

That is what most receivers have trouble with. Most are rated at best 6 ohms but the rf-83 and original rf-7 dip down to 2.8 ohms meaning if you are normall at 8 ohms, 4 ohms basically doubles and 2 ohms doubles again the wattage so if the speakers are playing at any significant volume and ask for 100 watts, at 2.8 ohms it needs basically 3-4X the wattage to compensate for the ohm drop so it would ask the receiver 300-400 watts per channel which even the best have trouble to do. The crown and qsc amps are stable down to 2 ohms.

[StephenM]

Most are rated at best 6 ohms but the rf-83 and original rf-7 dip down to 2.8 ohms meaning if you are normall at 8 ohms, 4 ohms basically doubles and 2 ohms doubles again the wattage

It isn't a matter of wattage, but a matter of current flow that's the issue. Even at the same level of wattage, current flow will increase by going from 8 down 4 and then down to 2 ohms. Using ohms law, you can calculate out the voltage and amperage needed to reach 100 watts for a 2, 4, and 8 ohm load. At 8 ohms, you would be running

~28 volts and ~3.5 amps.At 4 ohms, you're looking at 20 volts and 5 amps. At two ohms, you're looking at ~14 volts and 7 amps. This increase in amperage correspondingly increases heat and instability, and inevitably causes an amplifier not designed for the load to shut down in self protection.

For reference, a THX Select 2 receiver is designed to be stable down to 4 ohms and swing a 12.5 ampere peak in the front channels (equating to 625W at 4 ohms). A THX Ultra 2 receiver is designed to be stable down to 3.2 ohms and swing an 18 ampere peak on any channel (equating to a bit over 1000W at 3.2 ohms).

What is unfortunate is that the only third party I know of that really tests amplifiers is the mostly defunct "The Audio Critic" with their power cube test. That tests stability and maximum voltage into 8, 4, 2, and 1 ohm loads with a variety of phase angles (from 60 to -60 degrees). I wish more audio rags would give that kind of info, as it would make amplifier selection a whole lot easier.

[runninshine]

Most are rated at best 6 ohms but the rf-83 and original rf-7 dip down to 2.8 ohms meaning if you are normall at 8 ohms, 4 ohms basically doubles and 2 ohms doubles again the wattage

It isn't a matter of wattage, but a matter of current flow that's the issue. Even at the same level of wattage, current flow will increase by going from 8 down 4 and then down to 2 ohms. Using ohms law, you can calculate out the voltage and amperage needed to reach 100 watts for a 2, 4, and 8 ohm load. At 8 ohms, you would be running
~28 volts and ~3.5 amps.At 4 ohms, you're looking at 20 volts and 5 amps. At two ohms, you're looking at ~14 volts and 7 amps. This increase in amperage correspondingly increases heat and instability, and inevitably causes an amplifier not designed for the load to shut down in self protection.

For reference, a THX Select 2 receiver is designed to be stable down to 4 ohms and swing a 12.5 ampere peak in the front channels (equating to 625W at 4 ohms). A THX Ultra 2 receiver is designed to be stable down to 3.2 ohms and swing an 18 ampere peak on any channel (equating to a bit over 1000W at 3.2 ohms).

What is unfortunate is that the only third party I know of that really tests amplifiers is the mostly defunct "The Audio Critic" with their power cube test. That tests stability and maximum voltage into 8, 4, 2, and 1 ohm loads with a variety of phase angles (from 60 to -60 degrees). I wish more audio rags would give that kind of info, as it would make amplifier selection a whole lot easier.

That was a good explanation. Lots of good info, thanks for that. [H]

[Jay481985]

Most are rated at best 6 ohms but the rf-83 and original rf-7 dip down to 2.8 ohms meaning if you are normall at 8 ohms, 4 ohms basically doubles and 2 ohms doubles again the wattage

It isn't a matter of wattage, but a matter of current flow that's the issue. Even at the same level of wattage, current flow will increase by going from 8 down 4 and then down to 2 ohms. Using ohms law, you can calculate out the voltage and amperage needed to reach 100 watts for a 2, 4, and 8 ohm load. At 8 ohms, you would be running
~28 volts and ~3.5 amps.At 4 ohms, you're looking at 20 volts and 5 amps. At two ohms, you're looking at ~14 volts and 7 amps. This increase in amperage correspondingly increases heat and instability, and inevitably causes an amplifier not designed for the load to shut down in self protection.

For reference, a THX Select 2 receiver is designed to be stable down to 4 ohms and swing a 12.5 ampere peak in the front channels (equating to 625W at 4 ohms). A THX Ultra 2 receiver is designed to be stable down to 3.2 ohms and swing an 18 ampere peak on any channel (equating to a bit over 1000W at 3.2 ohms).

What is unfortunate is that the only third party I know of that really tests amplifiers is the mostly defunct "The Audio Critic" with their power cube test. That tests stability and maximum voltage into 8, 4, 2, and 1 ohm loads with a variety of phase angles (from 60 to -60 degrees). I wish more audio rags would give that kind of info, as it would make amplifier selection a whole lot easier.

Thanks. I gave as easy of an understanding as possible. You are correct sir.

[psg]

Most are rated at best 6 ohms but the rf-83 and original rf-7 dip down to 2.8 ohms meaning if you are normall at 8 ohms, 4 ohms basically doubles and 2 ohms doubles again the wattage

It isn't a matter of wattage, but a matter of current flow that's the issue. Even at the same level of wattage, current flow will increase by going from 8 down 4 and then down to 2 ohms. Using ohms law, you can calculate out the voltage and amperage needed to reach 100 watts for a 2, 4, and 8 ohm load.

Yes, but Jay is correct nonetheless... The extra current flow results in extra wattage. Music isn't calling for a given wattage from the receiver to drive speaker A or speaker B, it is calling for a given voltage. If, at a given frequency, speaker A has an impedence dip to 2 ohms and speaker B is still 8 ohms, then the same position on the volume dial will require 4 times the power at the same voltage for speaker A relative to speaker B.

[StephenM]

If, at a given frequency, speaker A has an impedence dip to 2 ohms and speaker B is still 8 ohms, then the same position on the volume dial will require 4 times the power at the same voltage for speaker A relative to speaker B.

Only if the voltage sensitivity of Speaker A and Speaker B are the same at that particular frequency. If the speakers are of comparable efficiency (sound output power/electrical input power), then an amplifier will have greater difficulty driving speaker A to a given output level that Speaker B, even though the electrical input power is the same and the voltage level required of the amplifier is lower for Speaker A, simply because the current flow is higher.

[Don Richard]

but doesn't address the room?

Actually they do. There are THX certified wall materials, doors, etc. Heck, if you've got the cash, you have them build your very own THX Reference theater, certifying the entire room as well as the equipment.

The only THX certification I found for home use is that they recommend certain packaged systems for different size rooms. THX also certifies sheetrock and doors for home theater soundproofing. I did not see acoustic specifications for home theaters on the THX website, but their website seems hard to navigate and those specs may (or may not) be buried there somewhere. They do have well defined.acoustic specs for commercial cinemas and studios, as one might expect.

THX certification would be of value for commercial installations, but for home theaters THX certs seem to only provide for approved minimal hardware standardization. And $$$ from the hardware manufacturers for THX, Inc.'s approval and endorsement.

[StephenM]

The only THX certification I found for home use is that they recommend certain packaged systems for different size rooms.

Don't know; it was only mentioned in the Secrets article that they would build you a THX Reference certified theater in your house for $250,000 (which has probably gone up in price since that article was written). They may well include that simply as a commercial item since precious few individuals will be shelling out that kind of dough. Either way, THX is aware of the role room acoustics plays, and if you've got the cash, they can help you! If not well...good luck []

but for home theaters THX certs seem to only provide for approved minimal hardware standardization.

Is that a bad thing?

Here is a THD+N graph vs frequency of a THX Select 2 certified $900 receiver at 4 ohms with a 5V and 20V output (~6 and 100 watts respectively):

http://www.hometheaterhifi.com/images/stories/2009/march-2009/onkyo-tx-sr706-receiver-thd-n-vs-fr-4-ohms-large.gif

Here is a THD+N graph vs frequency of a non-THX certified $1500 receiver at 4 and 8 ohms with a 20V output (50 watts @ 8 ohms, 100 watts at 4 ohms). Compare the red line of this graph to the red line above. That illustrates the value of THX to me.

http://www.hometheaterhifi.com/images/stories/2009/november-2009/Denon-AVR-3310CI-Receiver/denon-avr-3310ci-receiver-thd-plus-n-vs-fr-large.gif

I would also add that in addition to a solid minimum level of product quality, it is also a guarantee that THX Ultra 2 certified speakers will play nicely with a THX Ultra 2 certified receiver/amplifier and together, they will give reference level sound in a room up to 3000 cubic feet with a seating distance of 12+ feet.

[Don Richard]

The only THX certification I found for home use is that they recommend certain packaged systems for different size rooms.

Don't know; it was only mentioned in the Secrets article that they would build you a THX Reference certified theater in your house for $250,000 (which has probably gone up in price since that article was written).

I'll tell you what, for that price I will construct for you a dedicated home theater building on your property with a system consisting of Klipsch professional components (Jubilee LCR, etc.), top of the line video, component electronics, and acoustic treatments which will sound at least as good as what THX is not really offering.

I would also add that in addition to a solid minimum level of product quality, it is also a guarantee that THX Ultra 2 certified speakers will play nicely with a THX Ultra 2 certified receiver/amplifier and together, they will give reference level sound in a room up to 3000 cubic feet with a seating distance of 12+ feet.

Bose makes similar claims for their Lifestyle system, or at least their dealers do. If someone was thinking of going that way, then THX approved gear might be a better way for them to go.

[StephenM]

I'll tell you what, for that price I will construct for you a dedicated home theater building

I'll keep you in mind if I ever have that kind of cash burning a hole in my pocket []

Bose makes similar claims for their Lifestyle system, or at least their dealers do. If someone was thinking of going that way, then THX approved gear might be a better way for them to go.

Yeah, I'm pretty sure if I was given a choice between a Bose Lifestyle system and a Klipsch THX Ultra 2 system with a THX Ultra 2 certified receiver, I'd pick the THX system every time.

[Zen Traveler]

..Bose makes similar claims for their Lifestyle system, or at least their dealers do. If someone was thinking of going that way, then THX approved gear might be a better way for them to go.

Bose is a speaker company whereas THX sets standards that manufactures can choose to build products to their specifications...I agree to some it may not make a difference, but the flip-side of the argument is that a consumer can't rely on just what the manufacture want them to know.

The Thread Starter asked a good question. I contend that the average person doing their homework would see that the RF-7s are "8 Ohm compatible" and rated at 101 dB/1meter, Sensitivity and would surmise they could drive them efficiently with a lower end avr....Imo, that's where the THX Ultra II rating for power supplies becomes important, because it certifies that it can deliver enough current to multiple speakers, which have dips down to 3.2 ohms in a 3,000 cu ft room and it CAN drive an RF-7 Home Theater efficiently in a small to medium multichannel Home Theater.

[Don Richard]

Bose is a speaker company

No, Bose is a lifestyle company making junk posing as audio equipment. They will make noise, but so will a chainsaw.

[Zen Traveler]

No, Bose is a lifestyle company making junk posing as audio equipment. They will make noise, but so will a chainsaw.

I am not sure of the point you are making, but you brought up Bose in connection to a salient point that StephenM made about the THX Ultra II certified AVRS and I added the distinction of them being able to drive speakers with impedance dips such as the RF-7s...

.Fwiw, Bose products are only a "lifestyle company" to those who buy from that manufacturer and doesn't address certification perimeters with outside entities which THX most certainly does. Again, that doesn't necessarily make a THX Ultra II product better, but it could explain why a Bose product will NEVER be THX Ultra II certified. []

[Don Richard]

I am not sure of the point you are making, but you brought up Bose in connection to a salient point that StephenM made about the THX Ultra II certified AVRS and I added the distinction of them being able to drive speakers with impedance dips such as the RF-7s...

A lot of first time buyers are attracted to Bose because of their heavy advertisement in non audio related periodicals. THX certs seem to be oriented toward those same buyers and to those who would buy a system or components without actually listening to them. A listening test would confirm whether or not a particular receiver would be compatible with a particular loudspeaker and play loudly enough to satisfy that listener. That is basically what a particular THX certification does. A test that determines the THD of a reciever and it's power output tells absolutely nothing about how it sounds when hooked to a loudspeaker.

Bear in mind here that I am not talking about commercial THX certifications. Those give details that include acoustic parameters such as RT60, construction techniques such as not having parallel surfaces in the theater, and noise floor data along with sound system specs.

[Zen Traveler]

A lot of first time buyers are attracted to Bose because of their heavy advertisement in non audio related periodicals. THX certs seem to be oriented toward those same buyers and to those who would buy a system or components without actually listening to them. A listening test would confirm whether or not a particular receiver would be compatible with a particular loudspeaker and play loudly enough to satisfy that listener....

I agree with the above and auditioned everything I own, but:

1) The vast majority of consumers are not doing listening tests for a myriad of reasons....Alot that do, don't really know what to look for and presentation becomes the key.

2) Granted, that both of their target markets overlap, but people who go to Cinemas and watch movies in their homes are more than likely to "buy into" a THX endorsed "Lifestyle." Imo, at basic level they will have spent their dollars more wisely (imo) than what they could've purchased from Bose.

3) I can't argue that if a person wanted to get a lower end Klipsch Reference system with any mid-grade avr, that they wouldn't get spectacular sound without having to buy in to the THX marketing or certification.

4) Insofar as this thread is concerned and the OPs specific question...I couldn't understand why I couldn't play my RF-7 HT as efficiently with my 110 WPC Denon, as my 140 WPC Denon, when it wasn't that great of a difference. [^o)] That's when I understood that the vast majority of AVRs on the market could not drive the RF-7s, and those that could were THX Ultra II rated (whose big distinction is the ability to drive 7 speakers, that have impedance dips down to 3.2 Ohms in a 3,000 sq ft room).

Granted, there are AVRs that aren't ultra II certified that can drive them but those also come with expensive price tags. Then we get into the recent internet phenomena of cheap, external amps hooked up to mid level AVRs to achieve the same results...

5) This has brought us full circle to where we agree that one really should listen to a Home Theater before they purchase. What I found over on the AVSForum's "Klipsch Owner's thread" was that ALOT of people would come on and buy RF-7s (and other speakers) without even hearing them first based on what they were hearing (sic) on the internet...After going through some of my posts I realized that I was answering questions from folks, and the next thing I knew they were announcing what a great deal they found on the Internet and they LOVE their speakers!!!! Some of these people even became Gurus! []

[StephenM]

Here's my take on Bose vs THX: Bose is just a single company that aims to build and sell speakers that sound good to a large number of people while being stylish and unobtrusive. THX is a company that sets standards from the recording studio to the movie theater to your house. Because of this, they're in a unique position of being able to credibly claim that what you hear in your home with a full THX certified system is as close as is feasible (obviously the room is still a factor, but even that can be fixed with enough cash) to what the recording engineer heard when he mixed the soundtrack for whatever movie you're listening to. Is this a guarantee that you won't like another set of speakers or amplifier better? No, of course not. But all the same, it's a claim that no one else to my knowledge can match with the same kind of credibility.

[StephenM]

Some related reading: http://www.theaudiocritic.com/back_issues/The_Audio_Critic_28_r.pdf Specifically the piece by Floyd Toole, Audio Engineering, Science in the Service of Art. Think about the visual analogy, and the advantage of having a company that sets a standard at every level, from the mastering of the audio to your home.