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Discussion Starter #1
hello again everyone,

what amp would you wisely recommend for this setup?

-Stereo 2.0 with two KEF R900. Mostly for music listening (all genres)
-They are hooked meanwhile to an Onkyo TX-NR709. But I can use it as a pre-amp, this one have pre-out for 7ch.
- listening distance 12-15ft. Big living room 17x14x11 ft.

i contacted emotiva and they suggest me to buy two XPA-100 (rated 250Watt @8ohm THD<1%). I like them because I'll have channel separation, plenty of power I guess, and right now are 359USD each.

but of course I want to have a second opinion with you. the idea is they manage the full range since there'll be no bass for now.

Appreciated any comment.
 

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You could also look into the rotel power amps. I use an rb1080 with 200wpc into 8ohm. It's a big upgrade from a receiver.
 

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Discussion Starter #6
Another option could be a pro amp. Lots of people use them including myself and you get more bang for your buck,IMO. B+H photo is having a sale on some nice Crown amps and these are the ones that have very quiet fans. http://www.bhphotovideo.com/c/product/674284-REG/Crown_Audio_XLS1500_XLS_1500_DriveCore_Stereo.html
Thanks for your suggestion, I didnt know them, On paper they have great specs, and the price is really temptive. Do you have any link to a review??
What would be the drawbacks if any vs Emotiva xpa-100?... I assume the cost of two emotiva XPA-100 $700 or the rotel rb1080 $1000 must excel at someting or justify the higher cost.
 

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Discussion Starter #8
You could also look into the rotel power amps. I use an rb1080 with 200wpc into 8ohm. It's a big upgrade from a receiver.
seems like a good amp, but doing a little search on google I found some people worried about it driving 4ohms loads.
 

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Some people say that class D amps color the sound somewhat I think thats one reason many manufacturers stick to the tried and true class A/B amps. Emotiva makes a great amp for the money and no fan noise at all.
 

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Discussion Starter #10
Some people say that class D amps color the sound somewhat I think thats one reason many manufacturers stick to the tried and true class A/B amps. Emotiva makes a great amp for the money and no fan noise at all.
By color you mean it changes the freq. response. am i right?
 

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Yes, some reports say that the High end sounds more "airy"
 

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sonixpc said:
... what amp would you wisely recommend for this setup?

-Stereo 2.0 with two KEF R900. Mostly for music listening (all genres)
-They are hooked meanwhile to an Onkyo TX-NR709. ...
- listening distance 12-15ft. Big living room 17x14x11 ft.

i contacted emotiva and they suggest me to buy two XPA-100 ... right now are 359USD each. ... Appreciated any comment.
The speakers are 8-ohm and 90dB sensitivity. According to Audioholics, the AVR is "rated 110 watts per channel at the traditional measurement of 8 ohms, 20 Hz-20 kHz, 0.08% THD, and 2 channels driven." The AVR should be more than enough to drive those speakers. But since you're looking for more, I'd go with the pair of XPA-100s.
 

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By color you mean it changes the freq. response. am i right?
Hi sonixpc,
That may have been true for some older class D designs, but many of the most modern ones have HF output filters that are load invariant, that is, inaudible to human ears regardless of your speakers impedance. One benefit of class D amps (type, not brand) is that they are very efficient, thus consume less power in daily use, if you are so inclined. For your stated budget, one of these would power your KEFs without drama.
Monoblocks are cool looking, but the purported channel separation issue is audibly benign. What isn't benign is the increased possibility of ground loops over a single chassis.

cheers
 

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The speakers are 8-ohm and 90dB sensitivity.
Hi eljay,
Yes, just like the Q900 are "8 ohm, 91 db sensitivity". Which is probably why Dr Floyd Toole remarks there is far better info of the side of car tires. :)
As can be seen, it is anything but "8 ohms":


Amplifier "specs" being only slightly "less worse".:)

cheers
 

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Thanks for your suggestion, I didnt know them, On paper they have great specs, and the price is really temptive. Do you have any link to a review??
What would be the drawbacks if any vs Emotiva xpa-100?... I assume the cost of two emotiva XPA-100 $700 or the rotel rb1080 $1000 must excel at someting or justify the higher cost.
Here is some more info on the Crown XLS series. https://www.google.com/url?sa=t&rct...=O6qoIQ3AuUXhFkKeGrhONA&bvm=bv.97653015,d.aWw
And here...
https://www.google.com/url?sa=t&rct...7VFeA0VWLZxLcBCpQ&sig2=PfxS_MpGp7S9oASxFTd0mQ
 

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Discussion Starter #17
Hi sonixpc,
That may have been true for some older class D designs, but many of the most modern ones have HF output filters that are load invariant, that is, inaudible to human ears regardless of your speakers impedance. One benefit of class D amps (type, not brand) is that they are very efficient, thus consume less power in daily use, if you are so inclined. For your stated budget, one of these would power your KEFs without drama.
Monoblocks are cool looking, but the purported channel separation issue is audibly benign. What isn't benign is the increased possibility of ground loops over a single chassis.

cheers
Thanks for the explanation, This class D you mentioned is really good looking, pretty small, plenty of power and one thing I appreciate is fanless. but its price equals two emotiva xpa-100 (without S&H), Wont you incline for the emotica anyway? I mean what consistently is better on Class AB than even class D dont have?
 

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Thanks for the explanation, This class D you mentioned is really good looking, pretty small, plenty of power and one thing I appreciate is fanless. but its price equals two emotiva xpa-100 (without S&H)
You're welcome. Yes, the SDS-470C is around equal (slightly less without S/H) than the 2 Emotiva monoblocks. But??

Wont you incline for the emotica anyway?
No. But I'm not the one buying either.:)

I mean what consistently is better on Class AB than even class D dont have?
Nothing electrically or audibly.
Popularity? Weight? More heat? Guess it depends on how one defines "better" with this scenario.:)
 

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hello again everyone,

what amp would you wisely recommend for this setup?

-Stereo 2.0 with two KEF R900. Mostly for music listening (all genres)
-They are hooked meanwhile to an Onkyo TX-NR709. But I can use it as a pre-amp, this one have pre-out for 7ch.
- listening distance 12-15ft. Big living room 17x14x11 ft.

i contacted emotiva and they suggest me to buy two XPA-100 (rated 250Watt @8ohm THD<1%). I like them because I'll have channel separation, plenty of power I guess, and right now are 359USD each.

but of course I want to have a second opinion with you. the idea is they manage the full range since there'll be no bass for now.

Appreciated any comment.
None. Use the surround channels on the Onkyo to power the terminal for the highs. At 6 ohms ( the KEF says 8 ohms but use a multimeter and put it on the terminals. It will read 5.9-6.0. I've purchased some additional R series speakers and none have measured above 6 ohms. 5.7-5.9 is the reading I always get)
the Onkyo is rated at 130 watts per channel. Of course those #'s are never accurate RMS values so I would say with 4 channels driven it would deliver 115-120. × 2 and your right near the highest wattage specs of 250 for the KEF 900 providing it with 230-240.
Recommend purchasing 20 feet of canare 4S11. Got mine on bluejeanscable.com yet there are many other places. Believe 20 feet would be around 30$. It has 2 positive and 2 negative wires and you could connect to your Front L&R and Surround L&R with the same cable. Cut them both at the exact same length.
Tried connecting to both terminals on the towers but noticed no difference in a number of configurations and products.

Don't waste your money. If you feel the need, do what I did and demo one. Go that route to put your mind at ease. Have to admit I had the "more power bug for a few months" thankfully I did demos before learning of no difference.
Be surprised if you noticed any difference other than slightly cleaner bass below 80 Hz. If music is the primary and you want to get what's best for your system, purchase a subwoofer. The 900's can't handle anything below 35-40 Hz. 40 Hz most likely. Buy what's designed to handle the first 3 octaves. You're actually hurting your speakers when you play anything that has a signal below 40 Hz. Outside of classical, pretty sure all genres hit below that frequently. They try, and the 8' woofer puts up a good fight yet they're simply unable to reproduce that frequency.

Best bang for your buck subwoofer I've heard that gets the job done and exceedingly more is the NXG BAS 500 which is $240.

Here's the test bench on my 838 which is rated at 135 to give you a better idea of what your Onkyo will do at 4 channels

Test Bench
Two channels driven continuously into 8-ohm loads:
0.1% distortion at 134.9 watts
1% distortion at 173.4 watts

Five channels driven continuously into 8-ohm loads:
0.1% distortion at 110.5 watts
1% distortion at 129.3 watts

Seven channels driven continuously into 8-ohm loads:
0.1% distortion at 84.9 watts
1% distortion at 100.0 watts


Read more at http://www.soundandvision.com/content/onkyo-tx-nr838-av-receiver-test-bench#PyQ3HaYTkJelDBCJ.99
 

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Hi Tom,
Hard to tell if you're kidding and joking without any smilies, but...

At 6 ohms ( the KEF says 8 ohms but use a multimeter and put it on the terminals. It will read 5.9-6.0. I've purchased some additional R series speakers and none have measured above 6 ohms. 5.7-5.9 is the reading I always get)
No. That is measuring the DC resistance of the speaker, not the impedance. Different thing. Won't tell you a thing about the impedance over the audio bandwidth of the system, as I linked earlier for a Q900.

None. Use the surround channels on the Onkyo to power the terminal for the highs.
the Onkyo is rated at 130 watts per channel. Of course those #'s are never accurate RMS values so I would say with 4 channels driven it would deliver 115-120. × 2 and your right near the highest wattage specs of 250 for the KEF 900 providing it with 230-240.
Unfortunately that is also incorrect. You don't double power by biamping. It stays roughly the same. The amp is a voltage source and the XO a voltage divider.

cheers
 
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