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amp (or receiver) recommendation for Polk Audio RTi A7 floorstanding speakers

I started off building a 7.1 home theater system. Based on advice received here, I changed my plans. I'm re-purposing some of my components to a dedicated music system in another room. I would like some advice on this music system. (I'm keeping the home theater system in the smaller room and using smaller speakers with it.)

I am looking for a music system that will give me smooth, sweet, soft, silky treble with instruments like the Indian sitar or sarangi. These instruments can be challenging. I hope the system also has clarity and detail and enough punch for alternative rock in a large room.

I have two possibilities for listening location. One room is 18 feet x 22 feet with a tile floor, floor to ceiling windows on back wall and 8 foot ceiling. The front wall has a book case.

The other possible room is about 25 feet x 40 feet with a vaulted ceiling (approx 16+ feet at center). Back wall is also mostly glass. Flooring will be wood soon, but for now it is carpet. Neither room has curtains (or any window treatments) over the windows.

My old room was 11.5 feet x 11.5 feet and these speakers were too much for that small space (along with a large TV).

Let's assume I can arrange either new room so that my listening position and the speaker placement closely conforms to the "golden ratio" (http://www.ecoustics.com/articles/stereo-speaker-placement-optimum-sound/).

Here are the components I already own and would like to use:

  • pair of Polk Audio RTi A7 floorstanding speakers (8 ohms) - Sensitivity (1 watt @ 1 meter): 89 dB. Recommended Amp Power Per Channel: 20 watts → 300 watts
  • pair of Polk Audio RTi A5 floorstanding speakers (8 ohms) - Sensitivity (1 watt @ 1 meter): 90 dB. Recommended Amp Power Per Channel: 20 watts → 250 watts
  • Klipsch RP-250C Center Channel Speaker (probably won't use)
  • Klipsch R-112SW Subwoofer 600 W, powered
  • LG UP875 4K BLU-RAY PLAYER (plays audio CDs) (features HDMI, USB, and optical digital audio output)
  • computer with Asus X99 Deluxe II motherboard featuring Crystal Sound 3 audio (https://www.asus.com/us/Motherboards/X99-DELUXE-II/) (features USB, HDMI or optical S/SPIF output)
  • Focusrite Scarlett 6i6 USB audio interface (if needed) (https://us.focusrite.com/usb-audio-interfaces/scarlett-6i6)

Music will be played from my computer or the LG UP875 disc player.

What I have in mind is a 2.1 system with TWO pairs of front speakers (4 speakers total). I tried a dual front speaker setup briefly and I liked it, although I understand it is unconventional. But I have the speakers and I would like to try using them all. (If that is a really bad idea, even in a larger room, I'll give up on it.)

Also, I am curious to try bi-amp'ing and the speakers support it. If I use dual front speakers and bi-amp them 8 powered channels are required.

In a smaller room, I would not need a subwoofer with these front speakers. I don't know how that will turn out in a larger room. I don't listen to bass boosted music. But I assume I'll need a subwoofer. I assume I will not use the center channel speaker at all. I can return it.

Here's what I anticipate I'll need:

  • something with an amplifier
  • something with a sub out for the subwoofer
  • something to connect everything together (and, I guess, let me choose between the disc player and computer as sources)

What I do *not* need from the new components:
  • analog input sources
  • streaming, WiFi or networking (other than what I do with the computer)
  • home theater features or video support
My budget is about $1000, although I have some flexibility. But I only have about $2300 invested in the other components (not counting the center speaker, which I won't use, or the computer which is multi-purpose). So it doesn't seem to make sense to spend a whole lot more.

I am new to audio and home theater. I'm just learning now and I want to gain some experience before I increase my budget too much. Later, if I purchase much more expensive speakers, I'll get a more expensive preamp / amp combo. In my (limited) understanding the heart of an audio system -- where the money should be spent -- is the speakers and the amp. But with my most expensive speakers (the A7's) being $600/pair, it seems unreasonable to spend more than $1000 on a preamp+amp / integrated amp / stereo receiver (whichever is recommended) for this setup. If my logic is wrong, I guess I could be talked into increasing the budget to $2000 or so.
lowoverdrive
willemj
1,036 posts
 
Look at the manual of the Focusrite. From what I can see it has multiple analogue outputs, so you should be able to connect both main speakers and subwoofer to the Focusrite. From what I can see the Focusrite has balanced analogue outputs with TRS Plugs. The Yamaha has both Neutrik and TRS inputs, so you should be fine with a TRS to TRS cable to connect Focusrite to Yamaha. This way you can use the high pass filter on the Yamaha to relieve the main speakers from the very lowest frequencies (the sub will deal with those). Set it at something like 40 Hz, or maybe a bit higher.
Consult Focusrite about how to connect the sub to the Focusrite. At the very least this needs a TRS to rca cable.
You may consider a DSpeaker Antimode 8033 room eq unit to equalize the subwoofer and tame room modes. See here: http://www.theabsolutesound.com/articles/dspeaker-anti-mode-8033-dsp-subwoofer-equalizer-tas-204/ I have been very pleased with mine. In your case the stereo model may be convenient because it takes L and R inputs and has mono outputs (ask the DSpeaker importer for which types of cables you need).
If the Focusrite somehow cannot output signals to both the power amp and the sub, you will have to connect at speaker level, using an attenuation cable from the power amp’s outputs to the sub. But it had better be able to handle the Yamaha’s big power.
Since the Focusrite does not have tone controls (unless hidden somewhere) and for as long as you are only using a computer as your source, install the free Equalizer Apo (plus Peace interface) software on your computer. This is an advanced software equalizer that you can use for basic tone control, but also for more detailed parametric equalization. In fact, if you use the REW software and a UMIK-1 calibrated microphone you can do subwoofer equalization with this as well. But REW is hard work. So to keep it simple, use the Antimode for sub eq and the Equalizer Apo (without REW) as basic tone control. Use the high pass filter on the Antimode to relieve the sub from havng to reproduce the very lowest frequencies (say, below 15 Hz). This is a large room for a modest sub, and lowest frequencies are the hardest work (they need much more energy).
lowoverdrive OP
169 posts
 
Equalizer Apo claims to be Windows-only, so that leaves me out. But I can try Pulse Audio Equalizer on the computer, if needed.

The cables (TRS or TRS-to-RCA, etc.) don't sound like a problem. But I am confused by something very basic. I thought the connection had to flow in this direction: computer -> Focusrite -> Yamaha -> Speakers, which implies the speakers have to be connected to the Yamaha.

You said, "you should be able to connect both main speakers and subwoofer to the Focusrite."

I can understand connecting the subwoofer before the amp because it has its own internal power amp.

But how would the speakers be powered when connected to the Focusrite without the power running through the Focusrite? If the amp power is run through the Focusrite, isn't that potentially harmful?

Is there a good article somewhere that covers this topic? The articles I have read so far would all indicate that the speakers need to be connected to the Yamaha, not the Focusrite. I'm sure I'm missing some basic understanding.

BTW, the subwoofer is powered and is rated at a claimed 600W. I do have a less powerful Polk subwoofer that has speaker-level connects.
kalali's avatar
kalali
1,977 posts
 
Are you sure about Yamaha P5000S? The Yamaha P5000S appears to be a pro audio amplifier and already has built in gain controls but only supports balanced inputs. Not sure if it's the best option for your specific application.
willemj
1,036 posts
 
Sorry for the confusion I created (it was too early in the morning and I was in haste): I meant to write amplifier but I wrote speakers. The output of the Focusrite should obviously go to the Yamaha.
I thought you were using a Windows PC.
The Yamaha is indeed a pro audio amplifier with balanced inputs (both Neutrik and TRS). That is advantageous because the connection will be less noisy if your pre amplifier/DAC has balanced outputs as well (as would seem to be the case). In the case of the subwoofer connection, trs or Neutrik to rca cables are readily available for little money and are unproblematic. The presence of gain controls on the amplifier is similarly nice, because it allows you to tame the amplifier’s pretty massive output.
As is shown in the link that I posted earlier, its smaller sister the P3500S was recently tested and measured exceptionally well. The P2500S that I gave my son for his birthday sounds perfectly fine, and I am sure measures similarly well. These Yamaha amplifiers have variable speed fans (unlike much of the pro audio competition), but they run so cool that under domestic conditions these will never come on.
willemj
1,036 posts
 
I would use the bigger of the two subs in that large room. For connections, first investigate the analogue output types of the Focusrite (I could not quickly find the information). What are yo doing with the smaller Polk sub? Will you return it?
I think you are almost there with the music system for the big room.
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