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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
lowoverdrive OP
147 posts
 
Regarding connecting speakers... I will be connecting the USB DAC (Scarlett 6i6) to the Yamaha P5000S power amplifier in a very standard manner via two 1/4 inch to XLR cables. I will then connect my speakers to the Yamaha P5000S in the standard manner. No questions there.

When it comes to the powered subwoofer which has L/R RCA line in connections, it seems like I should be able to run two RCA cables from the Scarlett 6i6 to the subwoofer, bypassing the amp. Any problem with that?

I have 2 sets of L/R 1/4 inch analog outputs on the Scarlett 6i6 and I have them set to provide the same output. One set will go to the Yamaha inputs. The other set can go to the subwoofer it would seem. Does all that sound correct?
willemj
1,036 posts
 
Yes it does. However, the Focusrite outputs are not rca but TRS (balanced), and they are stereo. So you need a TRS (balanced) to rca (unbalanced) cable. If you are not using an Antimode in between the Focusrite and the sub, that cable should also be in a Y configuration, because you have to end up in one (mono) sub. If you were to use the Antimode 8033 Sii it has stereo rca inputs and mono rca output.
lowoverdrive OP
147 posts
 
@willemj - Thanks again for your help. I seem to almost have this figured out. Please let me know if I’m wrong.

Here are the panels on the amp, Scarlett 6i6 and subwoofer.
https://imgur.com/a/6Eh06
https://imgur.com/a/lMkPa (better rear of sw)

The subwoofer only has line level inputs labeled R and L/LFE. My assumption is that I should not use the mono LFE input if the signal isn’t low cut. Instead I am planning to use R & L (with 2 shielded RCA cables) from the Scarlett 6i6.

At the Scarlett I will use 1/4 inch mono to RCA adapters similar to these:

https://www.monoprice.com/product?c_id=104&cp_id=10429&cs_id=1042906&p_id=7176&seq=1...

I assume they should be mono on the 1/4 inch side, correct?

These will plug into analog outputs 3 & 4 on the Scarlett. (3 is L.) These outputs are mapped to be exactly the same as outputs 1 & 2.

On the subwoofer I’ll set the low-pass to 80 Hz. I’m under the impression low-pass on this subwoofer can’t be used when LFE is used, so a mono cable with RCA Y-adapter wouldn’t seem to be the right method (at least without something like the Anticable 8033 Sii).

1/4 inch TRS analog outputs 1 (L) and 2 (R) on the Scarlett will go to inputs A and B on the Yamaha via 1/4 inch TRS to XLR balanced cables wired according to the Yamaha manual (pin 2 to hot tip, which I think is standard).

Regarding the Anticable 8033 S-II, my plan is to try it without that and see what my ears tell me I might need (or want to try) next.

Actually, my next step will be to test the Yamaha A-S801 integrated amp.

I also have this (probably crazy) idea to try a Yamaha P2500S power amp (or smaller) and bi-amp my speakers (together with the P5000S), using the smaller amp on the high frequency inputs. Would that be worth trying?

I’m also inclined to try the Oppo UDP-205 at some point in the near future. Or maybe a more traditional audio USB DAC and see if I can tell any difference from the Scarlett. But I like sticking with just the equipment I have for now. The Yamaha P5000S should be here on Tuesday. I think I have all the cables I’ll need unless the above plan is wrong.

Do you see any other potential problems in regard to the connections?

One last idea I’m thinking about for further down the road is the suggestion by @erik_squires that "many audiophiles should make at least one pair of speakers in their lifetimes." I like the Polk cabinets and I don’t have a wood shop, so I am wondering what I might be able to do starting wtih the Polks as my base -- down the road, of course.


willemj
1,036 posts
 
So your sub has L and R inputs. That simplifies it a bit. All you have to do is to run a cable from L out from the Focusrite to L in on the sub. Ditto with R. I am not sure about the plug that you linked to (call Focusrite for advice). See here for more information: https://www.presonus.com/learn/technical-articles/Balanced-Unbalanced
Try the Antimode whenever you feel like it - I think you will love it.
I would cross over rather lower, like 40 Hz for a start, but you can experiment.
The Yamaha AS801 will be a bit easier, but the sound should be virtually the same, with a bit less dynamic headroom in that large room.
Bi-amping is not worth it in your situation, and adds a lot of worries.
An Oppo probably only makes sense if you want to play discs and/or want to connect a TV screen.
Once you have this up and running, stop worrying about the electronics (they will be more than good enough, even with far better speakers). Your three weakest links will be the main speakers (start saving for something like the bigger Harbeths), the room modes generated by the sub (get an Antimode), and the higher frequency reflections because of the hard walls, glass windows etc. (get some curtains, carpets, or whatever).
lowoverdrive OP
147 posts
 
@willemj "I am not sure about the plug that you linked to (call Focusrite for advice)".

I think the info I need is in the manual. Here's what it says:

"LINE OUTPUTS 1 to 4 – four balanced analogue line outputs on 1⁄4” (6.35 mm) jack sockets; use TRS jacks for a balanced connection or TS jacks for unbalanced. The signals available at all these outputs may be defined in Scarlett MixControl."

I believe RCA is unbalanced by definition (thanks for the balanced/unbalanced article - I'm reading that now).

This leads me to believe that the 1/4 inch to RCA adapters should be mono (TS), which is the style I have.

I can't see how using TRS (stereo) 1/4 inch to RCA adapters with RCA cables would make sense. Is there something I am missing?

(Granted, it will take me some time to get through that whole article you linked. It's a great article, but I don't think I'll understand it prior to the Yamaha arriving on Tuesday. I'll be ready to get things connected and give it a listen!)

If there is more to the connections than what the Scarlett 6i6 manual says, what would I need to ask Focusrite?

Thanks


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