Bi-amping RF-7-s.........

[SWL]

I'm considering powering the low freq on my RF-7's with my Crown amps and the high freq with tube amplification. Just purchased a JM Peach pre-amp.

Is there a tube amp that would be recommended for this purpose? Would this be beneficial with the 7's?

I'm new to two-channel and tubes. Any advice would be appreciated!!

[DrWho]

What kind of crossover are you gonna go with?

[SWL]

That is another question I have. I've seen that is what other guys are doing but how do I know what kind of crossover to use? The "picky" RF-7's............would they require something special/different than say, the Heritage line? RF-7's or not, I wouldn't know where to start as far as a crossover is concerned for this purpose.

[whell]

What are you trying to accomplish with bi-amping your RF-7's? My $0.02 would be that, before you invested in another amp or a cross-over, you experimented with your listening room to see if you can identify shortcomings that are impacting your experience with music reproduction from your system.

You could certainly try bi-amping, but not only will you need to find the sweet spot on the crossover that gives you the best results, but you'll have some challenges with gain-matching a SS amp and a tube amp.

I'd try looking for a simple solution first.

[SWL]

All I want is to get the best possible sound reproduction out of the 7's........for music, that is. I've read about some guys doing this with Jubes, etc. Gain matching ss and tube is a very good point.........that is what I'd like advice on. I'm all for going the cheaper more sensible route. You guys are good for that. As far as the room, I've treated it a couple of different ways with eliminating reflection points and slightly dampening the sound without making the room too "dead". It has been very beneficial so far.

If experimenting with crossovers would do the trick, then I'm all for it. From some of what I've read, research has been somewhat minimal, I was leaning towards bi-amping in addition to the use of crossovers. What other simple solutions would you suggest? Thanks for responding and I welcome more advice/opinions on this. If this is a waste of time and money, feel free to elaborate..........

[Zen Traveler]

I have owned my RF-7's for 4 years and I don't understand looking at the spec page and talking with other Home Theater enthusiasts how you go about finding the correct assessment of what the power requirements are. I have read knowledgeable people say that the cheapest of AVRs can drive RF-7s efficiently and others come on here and talk about an impedance dip on the RF-7's that require at least a 200 watt ss amp.

{edit: I have read all of the material on this forum about the different theories including the advice about getting an amp with twice the speaker's RMS rating but am having a hard time to get that to gel with the 102 dB @ 1 meter rating}

[Saturn5]

I have owned my RF-7's for 4 years and I don't understand looking at the spec page and talking with other Home Theater enthusiasts how you go about finding the correct assessment of what the power requirements are. I have read knowledgeable people say that the cheapest of AVRs can drive RF-7s efficiently and others come on here and talk about an impedance dip on the RF-7's that require at least a 200 watt ss amp.

{edit: I have read all of the material on this forum about the different theories including the advice about getting an amp with twice the speaker's RMS rating but am having a hard time to get that to gel with the 102 dB @ 1 meter rating}

Not to stray too far off topic, but I know what you mean. I have a pair of RF-7's that I was powering with a 20 year old Pioneer 100 W/ch AVR (VSX-5000). They could play quite loud - no doubt due to the high efficiency. I then added a QSC PLX-2402 (425 W/ch) and the sound quality difference was staggering. Even at similar loudness levels, the quality was much improved with the QSC amp. While the bass never seemed to be lacking before, now it has a more "real" feeling and sounds more effortless. That open and airy quality you hear people talk about. You could easily pick out the differences in an A-B comparison - even if both were set for exactly the same SPL.

My uneducated guess is most of the RF-7 efficiency is due to it's horn. The woofers - especially at their impedance drop - will require more current to keep up with the horns. The volume may still be there, but the bass won't have the same presence or punch behind it.

[Zen Traveler]

I posed a question on a thread at AVS forum asking, can all of the 100 to 150 wpc AVRs (Denon, HK, Yamaha, Pioneer) drive speakers with dips below 4 Ohms? I contend that they can't (effeciently) but I don't have the expertise to actually confirm that.

What I do know is that my Denon AVR 4806 is THX ultra II rated (i.e., can handle dips down to 3.2 Ohms) and was shown on a Benchmark test to be able to output 114 wpc into 7 channels continuously and sounds excellent--I wonder if on paper I have enough power to drive my HT efficiently.

I realize this may appear to be a thread-jacking and not a Home Theater question but I really admire you guys in the 2 channel Forum for your knowledge of audio;-) That being said I hope SWL gets an answer to his Bi-amp question with this Bump.

[DrWho]

I have owned my RF-7's

for 4 years and I don't understand looking at the spec page and talking

with other Home Theater enthusiasts how you go about finding the

correct assessment of what the power requirements are. I have read

knowledgeable people say that the cheapest of AVRs can drive RF-7s

efficiently and others come on here and talk about an impedance dip on

the RF-7's that require at least a 200 watt ss amp.

{edit: I have read all of the material on

this forum about the different theories including the advice about

getting an amp with twice the speaker's RMS rating but am having a hard

time to get that to gel with the 102 dB @ 1 meter rating}

Perhaps I can clear up some confusion...

The power rating has absolutely nothing to do with an amp's ability "to

drive" a loudspeaker. The spec that determins an amp's ability to drive

complex loads (like the RF-7) is the damping factor or output impedance

(both are expressing the same thing in different ways). As you already

know, a higher sensitivity speaker is going to require less power to

reach the same SPL and ultimately you don't need any more power than is

necessary to achieve the loudest SPL that you will ever encounter.

I think the source of your confusion is the trend for

higher

power amps to also have higher damping factors and lower power

amps tend to have lower damping factors. When someone recommends a

pro amp to drive the RF-7, it's not because of the increased power

handling that they sound better, but rather the insanely high damping

factors. This trend, however, is not always consistent. You can have

high power amps with low damping and you can have low power amps with

high damping. So as long as your low power amp has enough damping and

enough power to drive the speaker to the SPL's you desire, then the amp

should sound good (provided it doesn't screw up other things in the

process).

For what it's worth, there is also a trend for SS to have much higher

damping than tubes. I only bring this up because the damping factor can

have an influence on the frequency response too - which in the case of

horn loaded speakers can be problematic (considering horns rarely

present a smooth impedance response).

[MrMcGoo]

My RF-7s have been run on THX Select and Ultra2 receivers as well as separate amps all the way up to 625 wpc. The Ultra2 AVRs are ok, provided you set the mains to small and run them at an 80 Hz crossover. With the big amps, the mid-range improves and the bass tighens up on the RF-7s. I run the crossover at 50 Hz per BobG's recommendation, but only with the amps that have the current capacity.

The total wattage is not really necessary, but a high current amp is what makes the RF-7s shine. A good tube amp with 4 ohm taps and at least 40 wpc will also do well with 2 channel music.

Bill

PS: The high current amps generally have very low output impedance, so they have no trouble with the complex impedance of the RF-7s. B

[SWL]

With the Peach, Crown, RF-7 set-up would it be beneficial to use an active crossover even if I'm not bi-amping? I was checking out some active crossovers...........DBX and Berringer have some pretty affordable units. Am I on the right path? I'm using a passive crossover right now just to experiment with but after reading up on the subject it sounds like an active crossover would be better.

[Zen Traveler]

..PS: The high current amps generally have very low output impedance, so they have no trouble with the complex impedance of the RF-7s. B

I appreciate your and Dr. Who's response. I don't see anything that resembles that on the spec page or the link I provided on the "high current amp" thread for the AVR 4806. What kind of number am I looking for?

[MrMcGoo]

High current amps have big transformers, big caps and many output devices per channel. The other thing to look for on any amp running Klipsch speakers is a high signal to noise ratio, >100 db in a solid state amp. Always listen before you buy, if possible, or be able to return a poor sounding amp. Poor designs can have good S/N ratios and bad sound, but no hiss.

The trouble with most receivers is that they have one pair of MOS-FETs per channel. A good receiver like the B&K has three pairs of MOS -FET output devices per channel. The Sunfire receiver uses bipolar semiconductors. Transients require big caps. The measure for big caps is the amp's output peak to peak. My Sunfires put out 120 amps and 100 amps peak to peak.

On conventional SS amps, weight can be a good indicator for high current. The trouble with the weight theory is that there are many exceptions in one form or another of digital amps like the Sunfire.

Bill

[SWL]

I'm considering powering the low freq on my RF-7's with my Crown amps and the high freq with tube amplification. Just purchased a JM Peach pre-amp.

Is there a tube amp that would be recommended for this purpose? Would this be beneficial with the 7's?

I'm new to two-channel and tubes. Any advice would be appreciated!!

Nobody's gonna touch this one? I was hoping to find someone on here that has experimented with bi-amping the 7's.

In the meantime, I got an inexpensive active crossover just to experiment with (Behringer CX2310).

[Audio Flynn]

I'm considering powering the low freq on my RF-7's with my Crown amps and the high freq with tube amplification. Just purchased a JM Peach pre-amp.

Is there a tube amp that would be recommended for this purpose? Would this be beneficial with the 7's?

I'm new to two-channel and tubes. Any advice would be appreciated!!

Nobody's gonna touch this one? I was hoping to find someone on here that has experimented with bi-amping the 7's.

In the meantime, I got an inexpensive active crossover just to experiment with (Behringer CX2310).

Best I ever heard RF-7 was with a tube set up twice (VRD and 300B home made). I would upgrade the crossover caps and get a tube amp. Bi amping may get you to where you want; I never thought it had a place in home audio.

[DrWho]

I think the acoustical center of the HF horn is within a wavelength of the woofers....which I think means that proper time-alignment can be achieved inside a passive crossover (like via an all-pass or something similar).

I wouldn't quote me on that one, but I think it poses an interesting question about whether or not going active is necessary.

I think the future of hi-fi audio is going to see more active crossovers being used. The better systems out there require dedicated filters that aren't feasible to implement with passive components (especially at speaker level). It's kinda like the RIAA curves that work to minimize the distortions of vinyl. A lot of the cutting edge speaker design involves designs that require their own compensation curves. Without an active crossover this would be impossible.