To amp or not to amp my RF-7 IIs (w/ Onkyo TX-NR809)

[onawav]

I’m in the process of refreshing my home theatre, most of which is almost 10 years old. I have an RC-25 that I’ll be keeping for now as I think it’s as big as will fit in my entertainment cabinet center speaker hole. I have some old Klipsch bookshelf speakers I’ll be moving to my surrounds. I have an old Velodyne CHT-12 sub. I’ll be running a 5.1 system.

I have ordered an Onkyo TX-NR809 and a pair of Klipsch RF-7 IIs for my new mains.

The Onkyo is rated at 125w at 8ohm in 2 channels.

My question is, will this be a sufficient power source for the RF-7 IIs? I understand that the RF-7 IIs will dip down toward 3ohm during use and can require more reserve than some AVRs can provide. I’ve debated gabbing a couple of the Emotiva 200wpc monoblocks at some point.

What will I be missing in terms of HT sound if I use just the 809? What about music? I see that the 809 does offer bi-amping since I’m only using 5.1, but I guess it’s passive bi-amping which I’ve read provides little value? What do I stand to gain if I add an entry-level amp?

Lots of questions there. Thanks for your input in advance.

[StephenM]

My question is, will this be a sufficient power source for the RF-7 IIs?

The 809 is a powerful and robust receiver. My best guess is that the combination sounds at least passable at moderate volumes, although it is unlikely to be ideal, especially at higher volumes. However, it will cost you $0 to try it out and see what you think.

I’ve debated gabbing a couple of the Emotiva 200wpc monoblocks at some point. ...What do I stand to gain if I add an entry-level amp?

Emotiva has a strong following here, and people have used them with good effect on RF-7s. Presumably, the UPA-1s would do a better job of handling the impedance dips (less distortion, more power at the point where the impedance falls below what the 809 can effectively handle), and at the same time, take a load off the 809 to let it coast along driving your center and surrounds.

One thing I will add: if you are unsatisfied with the performance of the 809, I'd consider looking at something like the Parasound 2125 for about the same money as a pair of UPA-1s. At first glance,their power ratings aren't as high as comparably priced Emos; on the other hand, they are actually rated all the way down to 2 ohm loads. Moreover, some of their amplifiers have been 3rd party bench tested into very difficult loads without major issue: think 1 and 2 ohm loads with 60, 30, 0, -30, and -60 degree phase angles. Even the little wiener Zamp pushed on the order of 16-25 watts into the 1 ohm loads.

[cornfedksboy]

Welcome to the forum!

I'll agree with Stephen. One thing though...I'm not sure that the RC-25 will be adequate for the RF-7 IIs. If that's as big as you can go, I'd really consider getting RF-82s or RF-62s. Those certainly are not as good as the RF-7s, but your overall experience might be disappointing if you are constantly struggling to hear the voices.

[StephenM]

.I'm not sure that the RC-25 will be adequate for the RF-7 IIs. If that's as big as you can go, I'd really consider getting RF-82s or RF-62s. Those certainly are not as good as the RF-7s, but your overall experience might be disappointing if you are constantly struggling to hear the voices.

+1 there as well.

[SuBXeRo]

using the biamping function from the onkyo will help to deliver more power to the rf-7's. How much power extra, well, thats debatable since the overall power capacity isnt terribly awesome, just a downfall of a multichannel receiver. The rf-7's are power junkies despite their high sensitivity, they just require a lot of current on full range hence the low impedence dips. Heres my suggestion for the time being, adjust the crossover to the rf-7s to about 70hz and have the sub set at 80hz. By doing this you arent letting the 7's suck the life out of the receiver by having them produce the low notes which require a lot of power. You are letting the subwoofer do the heavy lifting with its own internal amp.

I think you should defnitly mess around with the settings though and see what you like best. I have run a similar configuration and i keep my towers on full range, i have an xpa-5 though. I wanted to see what the sound difference was like. I can tell that the sound is thinned when i up the crossover but the subs fill in what you miss. I keep them full range because i am a movie junkie and i want the maximum soundstage. The XPA-5 is a solid performer and cranks the rf-7's to levels where you can't really be in the room with them if you wanted to.

The benefit to external amps are that they are designed to serve a single function, AMPLIFY, POWWEEERRRRR OHOHOHOHO.. They dont have circuitry in them like a receiver that really limits design because there is signal circuitry within that would be sensitive to such large toroids which have a large EM field. Going external lets manufacturers design a unit capable of providing power needed without the limitations of a receiver. We also like to look for headroom with speakers. Most of us say atleast 50 watts more than what the recommended RMS of a speaker is for solidstate amps, this limitation doesnt exist with tube amps since the signal doesnt clip and essentially just runs out of gas. You surrounds and center will benefit from an external amp as well. Whats the benefit you ask? Chances are the power they will receiver will be cleaner and more refined, something that is essential to larger speakers and can only benefit smaller ones. Is it necessary? Sometimes no its not. Can it hurt to have? Absolutely not. If anything it gives you more options as to configuations you can support. Not all speakers are efficient like klipsch and require more power.

I dont know if you understand what impedence actually is when it comes to audio so ill explain a little. Impedence is the resistance of the driver to move. The lower the impedence the easier it is to drive. Now, with that said, a speaker is actually like a electric generator. When the amp makes power to move the speaker up, the speaker makes power on its way down and that power is returned to the amp, this is why you amp gets hot, the amp is dissipating that electric in the form of heat. The reason why so many receivers only handle 6ohm, 8ohm and 16ohm is because it cant adequately dissipate the heat. The drawbacks with higher impedence speakers is that its harder to generate power at 8 ohms then it is at 2 ohms. When the speaker is 8 ohms it is actually dissipating some of the energy and thus not returning it to the amp which keeps it cooler. This is why u see specs on the xpa-5 where the 8ohm power spec is practically half that of the 4ohm, its because electricity is wasted in the transfer between components! Now some can argue that it is harder to drive 2 ohm speakers which in some cases it is, if you look at it from the viewpoint that it is hard to dissipate the heat. I am no audio engineer but this is as i understand it. I could only assume that if you wanted to produce 100 watts at 4 ohms and 100 watts at 8 ohms, you would have similar sized transformers and heatsinks. In the real world, speakers are dynamic and their impedence is in constant flux, its 80hms one second and then its 5 ohms the next and so on and so forth.

hope it all helps, just some extra info!

[StephenM]

Couple notes:

Impedence is the resistance of the driver to move.

Impedance in this case is an electrical term; per wikipedia, it "describes a measure of opposition to alternating current (AC)." In other words, as impedance goes up, current flow goes down for a given voltage. Refer to Ohm's law.

The lower the impedence the easier it is to drive.

Not exactly. The lower the impedance, the more freely the current flows, and the more amperage & power you get for a particular voltage level; on the other side, you get more heat and instability in the amplifier. Moreover, for a given level of power, you have more current flow (and the accompanying heat and instability) with a low impedance speaker versus a high impedance model. Consider a 4 ohm and an 8 ohm speaker being driven by 100 watts. Per ohms law, the 4 ohm model will see a current flow of 5 amperes, whereas the 8 ohm model will see ~3.5 amperes.

Now, with that said, a speaker is actually like a electric generator. When the amp makes power to move the speaker up, the speaker makes power on its way down and that power is returned to the amp, this is why you amp gets hot, the amp is dissipating that electric in the form of heat.

No. Neither the speaker nor the amplifier "make power". In simple terms, the amplifier is like a relief valve, swinging voltage in accordance with the pre-amplifier signal and gain, allowing current to flow to the speaker. The circuit is completed when the current goes back to the amplifier and back to the wall. Heat is produced by the current flow meeting impedance. Because a 4 ohm speaker demands more current than an 8 ohm speaker for a given voltage, the amplifier gets hotter.

[onawav]

The 809 is a powerful and robust receiver. My best guess is that the combination sounds at least passable at moderate volumes, although it is unlikely to be ideal, especially at higher volumes. However, it will cost you $0 to try it out and see what you think.

A very good point. I felt like the 809 offered what I need initially. I'm definitely going to give it at least a couple weeks and see what I feel I need to make it live up to my expectations.

I've wanted Klipsch RF-7s since around 2003 or so when I first heard them in a showroom. I was simply blown away. Such detailed, revealing sound coupled with physical beauty. I'm excited to have a pair of my own soon.

Welcome to the forum!

I'll agree with Stephen. One thing though...I'm not sure that the RC-25 will be adequate for the RF-7 IIs. If that's as big as you can go, I'd really consider getting RF-82s or RF-62s. Those certainly are not as good as the RF-7s, but your overall experience might be disappointing if you are constantly struggling to hear the voices.

Thanks for the welcome. Seem like a good group of folks here! I'm concerned about the RC-25, too. I'll have to take some measurements [Edit: measured my furniture and I've only got 7.25' of clearance so the RC-62 or RC-64 won't fit. I could get a RC-52 in there, but that is only the modernized version on the RC-25 I have] .

In the interim, I'd guess the Audessy will help make some adjustments to balance things out and when I want to listen to two-channel sources, the RF-7 IIs can stand on their own.

[Zen Traveler]

[q... I've wanted Klipsch RF-7s since around 2003 or so when I first heard them in a showroom. I was simply blown away. Such detailed, revealing sound coupled with physical beauty. I'm excited to have a pair of my own soon.

A worthy goal and congratulations! Welcome to the forum and I haven't felt the need to ungraded since 2003.

[onawav]

I think you should defnitly mess around with the settings though and see what you like best.

I'm looking forward to playing with it. Can't wait to hear these things in my house! There are about 20,000,000 settings to tweak on the 809, so I should have plenty to play around with.

[onawav]

A worthy goal and congratulations! Welcome to the forum and I haven't felt the need to ungraded since 2003.

I can imagine why. I went to a local shop and listened to the original RF-7s for a few hours years back. I was enchanted. Worked up some cash and then other things came along. Life has its way of doing that to you. Fast forward 8 years or so and I finally got back around to it!

[SuBXeRo]

Ive been wrong before haha. I talked to an audio engineer and that what he told me. I am going to put myself through EE and audio college to learn it all myself, rarble. Thanks for the correction!

Couple notes:

Impedence is the resistance of the driver to move.

Impedance in this case is an electrical term; per wikipedia, it "describes a measure of opposition to alternating current (AC)." In other words, as impedance goes up, current flow goes down for a given voltage. Refer to Ohm's law.

The lower the impedence the easier it is to drive.

Not exactly. The lower the impedance, the more freely the current flows, and the more amperage & power you get for a particular voltage level; on the other side, you get more heat and instability in the amplifier. Moreover, for a given level of power, you have more current flow (and the accompanying heat and instability) with a low impedance speaker versus a high impedance model. Consider a 4 ohm and an 8 ohm speaker being driven by 100 watts. Per ohms law, the 4 ohm model will see a current flow of 5 amperes, whereas the 8 ohm model will see ~3.5 amperes.

Now, with that said, a speaker is actually like a electric generator. When the amp makes power to move the speaker up, the speaker makes power on its way down and that power is returned to the amp, this is why you amp gets hot, the amp is dissipating that electric in the form of heat.

No. Neither the speaker nor the amplifier "make power". In simple terms, the amplifier is like a relief valve, swinging voltage in accordance with the pre-amplifier signal and gain, allowing current to flow to the speaker. The circuit is completed when the current goes back to the amplifier and back to the wall. Heat is produced by the current flow meeting impedance. Because a 4 ohm speaker demands more current than an 8 ohm speaker for a given voltage, the amplifier gets hotter.

[StephenM]

I am going to put myself through EE and audio college to learn it all myself, rarble.

It's interesting and entertaining (and complicated and maddening) stuff, to me at least. Of course, I don't claim to be an engineer, or even close. I'm just a hobbyist who likes to try and separate the useful adjuncts towards porcine whole body cleanliness from the total hogwash floating out there.

[CECAA850]

I am going to put myself through EE and audio college to learn it all myself, rarble.

It's interesting and entertaining (and complicated and maddening) stuff, to me at least. Of course, I don't claim to be an engineer, or even close. I'm just a hobbyist who likes to try and separate the useful adjuncts towards porcine whole body cleanliness from the total hogwash floating out there.

And a fine job you do[Y]

[CECAA850]

I have to throw my 2 cents in while I'm at it. I agree wholeheartedly about the above comments about your center channel. By the time you calibrate your front 3 speakers, the 7's will be loafing along. There's no need for extra amplification. If you'r serious about HT, you've got to create a space for a center that can keep up with your mains. Either that or ditch your current center channel and run a phantom center (if your receiver is able to). Your center and sub make the home HT experience, DON'T skimp there. Virtually all your dialog comes from the center channel and it anchors the front sound stage. I'd wager that there's more info on that channel than any other. No one in their right mind would run a relay race with 2 Corvettes and 1 Cobalt and give the anchor leg to the Cobalt.

[onawav]

Thanks. I built the HT furniture by hand, so I could build a new one. It's just that this one has only been in service for a couple months! I wasn't able to find anything that got my 65" Panasonic plasma up where I wanted it and also hold my components. In my next revision I'll clearly need to add more space for the speaker and probably add another shelf for additional gear.

The RF-7 IIs will be fine anyway for 2-channel listening even if they are loafing along in HT useage for now. At least until I can upgrade the funiture/center.

[CECAA850]

Thanks. I built the HT furniture by hand, so I could build a new one. It's just that this one has only been in service for a couple months! I wasn't able to find anything that got my 65" Panasonic plasma up where I wanted it and also hold my components. In my next revision I'll clearly need to add more space for the speaker and probably add another shelf for additional gear. The RF-7 IIs will be fine anyway for 2-channel listening even if they are loafing along in HT useage for now. At least until I can upgrade the funiture/center.

That being the case, I'd try to set my receiver up as "no center channel" and disconnect the RC-25. I used an RC-35 for a while with a pair of RF-5's and it really wasn't good.

[cornfedksboy]

Thanks. I built the HT furniture by hand, so I could build a new one. It's just that this one has only been in service for a couple months! I wasn't able to find anything that got my 65" Panasonic plasma up where I wanted it and also hold my components. In my next revision I'll clearly need to add more space for the speaker and probably add another shelf for additional gear. The RF-7 IIs will be fine anyway for 2-channel listening even if they are loafing along in HT useage for now. At least until I can upgrade the funiture/center.

Good plan!

[onawav]

The Onkyo TX-NR809 arrived yesterday and I set it up with my old speakers.

It is clearly on a different level than my old entry-level Sony AVR. The clarity and power were substatial. I look forward to getting the RF-7 IIs next week and seeing what it can do with those.

[nezff]

seperates.

[onawav]

Update: I decided to grab an Emotiva XPA-2 during their holiday sale. Put in an order in early December. Unfortunately, it was out of stock at the time. So the wait began.

After a long wait, I finally got the XPA-2 in yesterday. Everything seemed to go smooth and work properly. I didn’t really have time to be listening critically last night, but as I gave it a quick test I soon found myself too involved to leave! The XPA-2 is clearly much more robust than the amps in the Onkyo 809.

The biggest difference I noted was in bass reproduction. The Onkyo couldn’t seem to get the woofers in the Klipsch RF-7IIs to really come alive.. no problem with the XPA-2, though. It sounded as if a subwoofer had been added in the mix even though I was in 2-channel “pure audio” mode that does not include the subwoofer.

The RF-7IIs seemed a bit more nimble and responsive under the control of the XPA-2. Altogether, it was a noticeable and pleasant change. I look forward to getting more time in front of the speakers and working through some more music for reference.