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Sanity check - matching amp to speakers

Yameyo

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Hi all

I'm looking at my next speakers, and as well as a number of models reviewed by Amir (mostly standmount models) I keep coming back to the Wharfedale 12.4s as an affordable possibility. My amp is a tiny WXA50, a model which Amir has reviewed on this site.

The WXA50 will put out 55 watts at 8 ohms. The Wharfedales have a nominal impedance of 8 ohms and a minimum impedance of 5 ohms, and Wharfedale recommend an amp between 30 and 200 watts. Their sensitivity is 89db.

I've done some reading, but to be honest it's still beyond me as to whether or not pairing the WXA50 and 12.4s would be silly. My current speakers have a nominal impedance of 6 ohms and a sensitivity of 86db. If I've got this right, at 6 ohm my amplifier can deliver about 82 watts.

My understanding is that the 12.4s would of course be harder to drive, but then are more sensitive so would also be louder for a given power?

As you can see, I'm probably getting myself tied in knots. I'm not set on floorstanders at all - just trying to get good bang for buck. Any guidance that the forum can spare would be greatly appreciated!
 

Inner Space

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Depends to some extent on the size of your room, your listening distance, and your preferred playback level, but 99% of the time 99% of people use about 5 watts max into an 89dB speaker, so your amp will be fine. There's a fetish for extreme power these days, but it hardly ever gets actually used.
 

TheBatsEar

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Maybe this helps:

Your speaker gets 1W and gives you 86dB at 1m distance.

The rules:
  1. Double the power into the speaker and you gain 3dB.
  2. 10dB more sounds like doubling the volume.
  3. Add a 0 to the watts and you get 10dB more out, so +10dB from 1W to 10W, +10dB from 3W to 30W.
  4. Doubling the distance reduces by 6dB

dB outputW/1m
861
892
924
958
9816
10132
10464

If you do the math and put 32W into your speaker, you get 89dB at 4m distance with those speakers.

How loud is 89dB? Plenty:
 
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Yameyo

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Thank you both, your replies were very helpful. I might well go for the Wharfedales!
 

Snoopy

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I had the wxa50. Loudspeakers at first heco metas 301 XT.

Upgraded to wharfedale Evo 4.2.

The wxa50 was constantly at 95-100% of its maximum volume when I was watching movies with it. And there wasn't that much left when I was listening to music.

Upgraded to the Cambridge Cxa81 and immediately things improved considerably. I would stay away from the wxa50 and get something more powerful.


I had constantly issues with streaming as well (hardwired, new router, 100mbit download) , songs suddenly skipping etc.
 
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Yameyo

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Hi Snoopy. Thanks for the advice - I'll definitely factor it in.
 

Keened

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Amp/Speaker power matching I think is a legacy of analog volume controls. If the DAC has a sweet spot (best distortion rating at -Xdb out) and/or the amp has a sweet spot (best distortion rating at Xw and/or minimum input signal at -Xdb to avoid clipping) you need to find something where most of the music you're playing falls within the sweet spots.

The answer to this is digital volume control which it seems the WXA50 uses so you shouldn't lose any fidelity on the DAC side and it minimizes the amp distortion starting at ~10W and goes all the way up to 50W without an issue so they should work together well for listening at anything other than nearfield.
 

MAB

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I have three of the WXA-50, and like them. One is at my 90 year old mom's house... I have had no issues with network stability, but my experience is limited to the three I own and my network. They measure well, and sound great. I like the functionality. They drive 4 Ohm speakers no problem. At 50W, they do not play overly loud, which may be an issue for you. The great news is that they function great as a preamp, so you can add an amplifier of your choice later.

So, if you like the Warfedales, the WXA-50 will drive them just fine until you run out of power. If you do find that power is an issue, go get yourself a nice amp to compliment and use the WXA as a preamp/DAC/Streamer. You could also integrate a powered subwoofer with the WXA-50, which is a different upgrade path but one that would effectively increase the power headroom to your main speakers. Subwoofers, when set up properly, can have a massive benefit to both bass as well as the performance of the mains.

I like Yamaha. They still make fine musical instruments. And they still create consumer electronics that have engineered performance. So I would hang onto the WXA-50 and get the speakers you want, and see where to go from there!
 

Cbdb2

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Going to 100watts is only 3db louder, barely noticeable, and 200watts is 6db, a little louder. Try what you have, the room is also a factor.
 
Last edited:
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Yameyo

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Thank you everyone for taking the time to send me some advice. I really do appreciate it.
 

valerianf

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My WXA-50 is driving a pair of Polk R150 as surround speakers.
Their efficiency is 89 dB and the WXA-50 is sufficient.

But the WXA-50 has an issue: it has a very low gain as measured by Amir.
Thus it will never go to a loud level.
It is a design flaw.
 
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Yameyo

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Thanks Valerianf. I'm willing to bet that that I don't listen at a particularly loud volume. I think I'll pick up an SPL meter to measure listening volumes with my current speakers.
 

Holmz

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Maybe this helps:

Your speaker gets 1W and gives you 86dB at 1m distance.

The rules:
  1. Double the power into the speaker and you gain 3dB.
  2. 10dB more sounds like doubling the volume.
  3. Add a 0 to the watts and you get 10dB more out, so +10dB from 1W to 10W, +10dB from 3W to 30W.
  4. Doubling the distance reduces by 6dB

dB outputW/1m
861
892
924
958
9816
10132
10464

If you do the math and put 32W into your speaker, you get 89dB at 4m distance with those speakers.

How loud is 89dB? Plenty:


I think that those number are for RMS watts.
With crest factor, the peak power required is 20x more than the RMS power.
 

TheBatsEar

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I think that those number are for RMS watts.
With crest factor, the peak power required is 20x more than the RMS power.
True, but i don't think this matters much for 99,9% of living room listeners.
 

Holmz

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True, but i don't think this matters much for 99,9% of living room listeners.

Your math said 32W (RMS) to get 89dB SPL.
However the music has crest factor, so if the amp is 32W RMS, then one can hit 89dB SPL on the peaks, and the RMS SPL is limited at 76 dB before clipping ensues.

It will be fine if they listen below 75-80 dB SPL.
It will not be fine if they intend to listen above 80 dB SPL.

If some clipping is OK, or the music is more compressed, then they get to higher SPL numbers before it sounds ratty.

The 55W that the OP mentions is going to about 3dB more than the 32W in the example.
So I would expect this to be falling on its face around 85-90 dB. Which is plenty unless the OP is looking for a party level system in a large room.


Thanks Valerianf. I'm willing to bet that that I don't listen at a particularly loud volume. I think I'll pick up an SPL meter to measure listening volumes with my current speakers.

The phone apps like NIOSH are easy to pick up.

I would not buy a new amp, until you run things with your existing amp. (It is already paid for.)
 
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Yameyo

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Thank you everybody for the assistance and the useful suggestions. It's been really helpful, not just for choosing speakers, but also understanding the real world significance of published specs.
 
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