KLIPSCH RF7's BI-AMP...?

[thirdeye]

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[thirdeye]

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[timbley]

You already are doing this, or you are going to? I'm curious to find out if you think it makes an improvement from just using one amp. Those amps should be able to run the RF-7 handily without bi-amping, so I'll be a little suprised if you find a big improvement. But you never know until you try.

I tried passive bi-amping with 2 Panasonic SA-XR50 receivers, figuring they'd benifit from sharing the current load a little. I thought I heard good things from time to time, but it always ended up being because of something other than the bi-amping, such as the tone controls being changed without me realizing it. In the end, that configuration really didn't amount to much. A single SA-XR50 running the whole speaker really sounded just as good, maybe even a little better.

Right now I'm experimenting with a Behringer DCX2496 active crossover, bypassing the speaker's passive network. So far I'm really impressed with the sound. The bass is tighter, the mids sound clearer, the highs more extended and less edgy, and I get a much more convincing stereo image, especially with some careful attention to the EQ. Almost all my records and CDs sound better. A few of them don't for some reason, mostly electonic music. Kraftwerk's "Tour de France" sounds too smooth and laid back to me now. "Neu!" had sizzling energy and slam before, which I liked. It sounds like a poor recording now, with murky bass and slightly muffled highs. I'm at a loss to explain that when so many other recordings sound so much better. I'm going to put the passive crossovers back in at some point and listen to them again just to make sure I'm not delusional.

[thirdeye]

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[Spkrdctr]

Hey guys, what are you doing for "passive Bi-amping?" Thanks for the info!

[timbley]

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On 4/5/2005 1:01:57 PM Spkrdctr wrote:

Hey guys, what are you doing for "passive Bi-amping?" Thanks for the info!

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Hey Spkrdctr,

I'm not sure I understand your question, but when I was "passive bi-amping" I was running two SA-XR50 recievers with cable splitters from the various devices feeding each receiver. The remote control kept the volumes synched. I ran one reciever's speaker cables to the HF terminals and the other to the LF terminals on the RF-7s.

[Erukian]

Personally, i'd take a fun/exciting, lively amps and hook it up to the two woofers. Then take a mellow/laid back/neutral amp like the HK 430 and hook that up to the tweets. Mix and match different amp sound signatures to create your uber RF7's for your musical preferences.

-Joe

[TBrennan]

spkrdctr---What I did for passive bi-amping was use passive filters between my pre-amp and amps that sent below 500hz to one amp and above 500hz to another. Each amp was connected directly to the driver terminals (above 500 to compression driver, below to woofer) with NO passive filters at the speaker level.

That's passive bi-amping. The other method discussed here is "fool's bi-amping" as practiced by readers of Stereophile and Absolute Sound.

[MrMcGoo]

The bi-amping should work as long as the gain ratio is the same on both amps. For example 1 volt of input on both amps produces 29 volts of output.

With a good 200 wpc amp on the RF-7s, I would call it good enough and would use the second amp for something else. The alternative is getting a more powerful amp for more headroom.

I believe someone makes an amp that is SS for bass and tube for higher frequencies. Is that fool's bi-amping?????

Bill

[TBrennan]

Bill---It's not "fool's bi-amping" if the signal is split BEFORE the amplifiers. If split AFTER, then yes, that's fool's bi-amping.

I've bi-amped myself using SS for bass and tubes for treble, it can work well. I've used both active and passive filters for bi-amping.

I'm now thinking of bi-amping my Altec 605s with a Teac T-amp for bass and a Sonic Impact for treble.

[MrMcGoo]

Tom,

I think that the name "fool's bi-amping" is a bit harsh, even when you understand the reason for it.

I am a believer in getting a bigger amp when more power is needed. The different topologies available are also valid reason's to bi-amp.

Many new folks like to experiment, but they are generally not qualified to design their own crossovers. Many of those folks that do use their own external crossovers probably introduce colorations that harm the sound quality as much as the bi-amp helps.

Bill

[thirdeye]

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[Spkrdctr]

Even though I am not all that taken with Deans cross over mod (at this time), he can quite easily change your crossover to drop the freqs for both horns a lot. This can be accomplished quickly with the addition of a resistor or increasing the value of an existing resistor. I would talk with Dean and have him triple or quadruple the resistor value to really tone the horns down A LOT, for your preference. It is easy to do, looks factory and does not waste money on other ideas. You will have to push Dean to use rather large resistor values compared to what he is used to, (it may freak him out!)but he can do it. Those RF-7s will then wake up and rock your world! Good Luck!

[thirdeye]

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[MrMcGoo]

I do not find my RF-7s lack bass or sound harsh. A 200 wpc amp should help the bass. Also, use corner placement for the RF-7s, if possible. Corner placement will boost the bass a bit.

A good 200 wpc amp will clip less and sound better on the high frequencies in addition to improving the bass tighness and output. DeanG's crossover mod will help as well.

RF-7s are excellent speakers but cannot improve room acoustics. Proper placement helps with the room, but room treatments may be needed.

Bill

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[minn_male42]

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On 4/6/2005 6:55:24 AM thirdeye wrote:

Okay guys, I just got the 7's set up, the 100w would be fine I am not disputing this, however!!! the real issue is man this things are overly horned!!! too much upper range and even when you try to crank it volume wise the bass just never gets going enough, NOT necessarily bright just WAY underpowered at the woofer level, they are working and sound decent but can not keep up with the horns, I have a feeling yes at this point the Passive Crossovers in the Cabinet must be Stripped away to get rid of the power SUCKING inductors in front of the woofs, but if I do this I will have to just Go all the WAY, In other words What do you Guys think about the MARCHAND TUBE Crossovers to handle this Thrown in before the AMPS? And of course still attempt to use the 200w forte on the Bottom and the 100w forte on the top? I need serious recommendations if this will be worth the cost of admission... Basically If anyone is familure with the AVANTGARDE DUO system that is my favorite speaker by the way but just an insane amount of money, But anyway this in my mind would be kinda similar basically Running 200w Subs DUal 10's in each cabinet and having crossed over of course to deal with this correctly?

--Now all that being said, I have not had the 7's completly broken in, but Damn KLIPSCH has to be kidding me if they believe this system was developed to take advantage of these very well built 10's , You can not even get them going in a standard hook up situation I don't care what you do , Short of #1- Putting in An EQ and Cranking Everything Under 500hz, or Try Using the standard Tone Controls and Cutting the Treble to like NON-existant, and BASS to the MAX, OR haveing a RECIEVER capable of LOUDNESS control on and off with a bunch of ROCK, OPERA, JAZZ settings to help overcome the In-Balance,, AND THESE SUCKERS do have a pretty DECENT gap in In-Balance, and it may be due to the rediculous Efficiency.... Because I have heard the RF3's in a friends system and the bass is semi-balanced with the horn..but were only 98db vs. 102 in the 7's.

Here nor there, I want to make these Sleeping Giants Perform so I need the next step, as they can't be a bad speaker, but just not even close to the potential.... I think at some point klipsch put out the RF5's with Built in Sub amps at one point, im not sure but did they? I mean these may need that type treatment to make worthwhile... And no guys the Higher power of output with 2 AMPS is not needed, but Needed to maybe get some type of balance, this is a project to tame the 7's... I have 4 weeks to make some magic happen or they may be crated up and sent back if they cant stand on there own without a SUBWOOFER, and YES I HAVE a 3000.00 Subwoofer Backing them up too, and they sound Absolutely wonderfull with that sucker Fireing backing them up, but this should not be nearly as necessary as it is......... BIG towers with big Drivers should move some Pretty decent air on there own, Thats my MISSION!!

THanks guys, not on a soap box just my thoughts.... I appreciate every one that has figured it out, and any opinions too.

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your amps cannot handle the impedance drop in the RF-7's at the lower frequencies...

as has been pointed out in more than a few threads, the RF-7's impedance drops below 3 ohms in several areas in the bass frequencies....

it is pretty obvious that your amplifier(s) cannot handle this impedance drop

get yourself a quality amp that has some guts to drive low impedance loads and you will get a ton of bass from the RF-7's

for music applications (two channel) you should never need to use a sub with these speakers

[timbley]

Hmm, I never had a problem with the RF-7s lacking bass. And that was running them with a little Panasonic SA-XR50! My girlfriend would ask me to turn down the thundering bass regularly. I now have an EQ, and the bass controls are notched down at a few room modes in the bass. Definitely no gain is needed.

These speakers actually have good, flat response from about 17K to 35hz or so. The horn may be more directional than the 10's so it beams to your listening position better, making it seem too loud. Room acoustics are probably the primary culprit here.

If you look at Klipsch's crossover circuit, you can see there's an attenuation circuit that cuts the horn way down at (I'm guessing) 9K. The speaker's impedance falls to 2.8 ohms around 9K, and that's probably because of this bypass circuit, which only presents a 1 ohm and a 2 ohm resistor as a load in parallel with the tweeter at that frequency. Messing with those resistor values could change everything.

If you go with active crossovers, you'll need some kind of EQ for the tweeter to bring it down toward the middle of it's range, and boost it a bit toward 20K if you want your highs extended. My most aggressive EQ is on the tweeter, with about a 5db cut at 4.8k, and a 10db gain at 17k. I also have a 10 ohm resistor in series with the tweeter to bring it down a few db, although that could be done by controlling the gain output on the DCX crossover. I just happened to have those resistors, and they bring the tweeter pretty close to even with the woofers overall. Furthermore, after adjusting my speakers for flat response in the room, I've applied a gentle treble roll off using the graphic EQ function of the DEQ2496. I like doing it that way because I find the desired treble roll off is the main thing that differs between different recordings, and the graphic EQ makes it easy to change this without messing up everything else.

[thirdeye]

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[timbley]

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your amps cannot handle the impedance drop in the RF-7's at the lower frequencies...

as has been pointed out in more than a few threads, the RF-7's impedance drops below 3 ohms in several areas in the bass frequencies....

it is pretty obvious that your amplifier(s) cannot handle this impedance drop

get yourself a quality amp that has some guts to drive low impedance loads and you will get a ton of bass from the RF-7's

for music applications (two channel) you should never need to use a sub with these speakers

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You might want to look into this notion also. An amp can make a big difference, despite it's power rating. I just picked up another cheap digital receiver last night, a JVC F10 digital hybrid feedback design. TheChairGuy on audiocircle has been raving about it, claiming it sounds great through it's analog inputs and can handle difficult impedance loads. For 159 bucks, I figured it was worth a try.

Sure enough, this little wonder fleshes out bass much better. It's rated at 100watts, just like my Panasonic was, but it digs way deeper. Playing pink noise and looking at the EQ, I can see that the bass doesn't look elevated or boosted. But the difference is obvious whenever some really deep bass gets going. It's really solid and deep with this amp. I thought a heavy truck was going outside at one point because I felt a powerful low frequency rumble. It was my RF-7s!

The little JVC is really a sweet sounding thing. It's warmer and richer than the Panasonic. I think it's a good match for the Behringer crossover's analog outputs, and the RF-7s impedance issues. I know it's hard to believe that something with JVC on it could make good sound, but I challenge any of you to try the F10 with your RF7s, and tell me it doesn't sound smooth and sweet, and dig deep in the bass.