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Post by Deleted on Aug 31, 2015 5:20:24 GMT -5
So I have had the XPA-2 Gen2 for a couple of months and I'm pretty happy with it except there is some buzzing in the speakers that's annoying me. This is not the typical hum you get with a grouploop issue. I know what that sounds like. The noise is not heard in the listening position..yet(much more effecient speakers soon).
But when I put my ear against the speaker I hear the typical white noise from the tweeter which is fine but from the woofer I hear what sounds exactly like the transformer noise I hear when I put my ear against the amp itself. To me it seems that this is some type of bad isolation within the amp itself. I've emailed emotiva about it and I'll have to see what they say. I live in Sweden so shipping it back is not an option due to costs. When testing with my speakers connected to my receiver there is no noise at all from the woofer. So kind of dissapointed about the quality of this amp even though the rest of the build quality seems good. I've also heard the clicking noise I've read about in other threads which seems to be due to screws being to tight in the chassi. This is less of a problem for me personally but still adds to the impression of average build quality.
Anyone else had this experience? Is this within spec of the amp perhaps?
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Post by Boomzilla on Aug 31, 2015 8:02:05 GMT -5
Sorry to hear of it. Mine were dead silent. But both of mine were generation one models...
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Post by geebo on Aug 31, 2015 8:05:55 GMT -5
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Post by Deleted on Aug 31, 2015 8:33:13 GMT -5
Yes, something like this might work..not sure what I can get here in Sweden though. Pretty expensive thing but could be well worth it IF it fixes the problem. But would want to test before buying. At the moment I have an inexpensive power surge protector with RF sheilding but this seems next level. |
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Post by Deleted on Aug 31, 2015 9:00:20 GMT -5
Reading more about this on a swedish forum it seems like electronics that are optimized for US current i.e 60Hz will have more problems with this than stuff made for 50Hz when used in a 50Hz power grid. From what I'm reading there is a strong possibility that this has to do with DC entering the transformer. Any tips of power strips that can be bought in europe with a DC filter..seems hard to find one and the ones I find are over $1000. Most people seem to build their own with this kind of stuff www.lcaudio.com/index.php?page=316 |
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Post by Deleted on Aug 31, 2015 9:15:06 GMT -5
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KeithL
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Post by KeithL on Aug 31, 2015 10:42:51 GMT -5
A tiny amount of noise is normal. All amps have a noise floor, and whether that noise floor is "dominated" by hiss (white noise) or hum depends on a lot of things. A DC offset on the line may cause the transformer to run hotter, and may cause a little bit more mechanical noise in the transformer, but isn't all that likely to cause electrical hum (which is what hum you hear coming from the speakers would be). However, IF there was DC offset on your power circuits, then the CMX-2 would eliminate it (and it's a lot less than 399 pounds). |
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Post by Deleted on Sept 1, 2015 3:12:56 GMT -5
A tiny amount of noise is normal. All amps have a noise floor, and whether that noise floor is "dominated" by hiss (white noise) or hum depends on a lot of things. A DC offset on the line may cause the transformer to run hotter, and may cause a little bit more mechanical noise in the transformer, but isn't all that likely to cause electrical hum (which is what hum you hear coming from the speakers would be). However, IF there was DC offset on your power circuits, then the CMX-2 would eliminate it (and it's a lot less than 399 pounds). Ok but is there a version on CMX-2 that works in Sweden? Different plugs and voltage here.. If the transformer is not causing the electrical hum then I'm not sure what the problem is. Either my unit is faulty or it's within spec. Like I said it doesn't bother me that much atm but I'm afraid it will with my new speakers. And also it feels like a sperate amp that is considered to be one of the best should be more quiet then my bugdet receiver. |
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Post by trinhsman on Sept 1, 2015 6:15:07 GMT -5
A tiny amount of noise is normal. All amps have a noise floor, and whether that noise floor is "dominated" by hiss (white noise) or hum depends on a lot of things. A DC offset on the line may cause the transformer to run hotter, and may cause a little bit more mechanical noise in the transformer, but isn't all that likely to cause electrical hum (which is what hum you hear coming from the speakers would be). However, IF there was DC offset on your power circuits, then the CMX-2 would eliminate it (and it's a lot less than 399 pounds). Ok but is there a version on CMX-2 that works in Sweden? Different plugs and voltage here.. If the transformer is not causing the electrical hum then I'm not sure what the problem is. Either my unit is faulty or it's within spec. Like I said it doesn't bother me that much atm but I'm afraid it will with my new speakers. And also it feels like a sperate amp that is considered to be one of the best should be more quiet then my bugdet receiver. Have you tried a different speaker in your set up? I recently re-did a pair of Snell E II's with new internal wiring and a custom made Artic Birch cabinet. When I put them into the mix I get a very small hiss out of my equipment. I used to have an XPA2, but now have a Pass Labs X150. That's a much higher level amp than the XPA2. Now, with my old Snell Type C's I got absolutely no hiss. Perfectly quiet. But with the E II's that I have new internal wiring in, I get the hiss. It is very slight and I have to put my ear up to the speakers to hear it. It is so slight you can't hear it from the listening position at all. The E II's are giving me such a nicer sound that it is worth it to leave it the way it is. Based on my research the level of hiss I am hearing is considered normal. If yours is loud enough to hear from 4-5 feet away, or it gets louder as you turn the volume up, you may have an issue. IMHO. |
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KeithL
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Post by KeithL on Sept 1, 2015 8:29:43 GMT -5
Sorry, no, the CMX-2 won't work on your 220V in Sweden. However, basically, a faulty transformer, or even one that is simply a bit noisy, will cause mechanical hum, which comes from the windings and/or plates in the transformer vibrating from the forces generated by the magnetic field inside. You'll hear that coming from the amp itself, or from the shelf it's sitting on vibrating. The same is true for a hum caused by excess current draw due to a DC offset on the line. An imperfect transformer is very unlikely to cause electronic hum from the output. However, yes it is true that a very powerful amplifier will often hum or hiss more than a less powerful product, even one of otherwise lower overall sound quality. A 200 watt amplifier with a S/N of 100 dB will produce 10 times as much hum or hiss as a 20 watt receiver with the same 100 dB S/N... and a more powerful amplifier will have to have a much higher S/N ratio to be equally quiet as a less powerful one. (For pretty much the same reason why the engine on a racing car is a little noisier than the one on your family car.) If we're talking about a relatively loud hum, and it drops off when you disconnect the source from the amp, then it's probably some sort of ground loop, or the hum is coming from your source itself. If it's a steady level, and it stays, even with no input connected to the amp, then it's probably normal. Note that, because hum is a low fixed frequency, how much of it you hear will also depend on your speakers, your room, and how everything is set up. (If your room has a resonant mode at your line frequency - 50 Hz, then that will acoustically boost whatever hum is there; likewise, having a very live room, or a very efficient speaker, or putting the speaker in a location - like a corner - that boosts the bass, will also boost the hum - since hum is just a certain frequency of bass). A tiny amount of noise is normal. All amps have a noise floor, and whether that noise floor is "dominated" by hiss (white noise) or hum depends on a lot of things. A DC offset on the line may cause the transformer to run hotter, and may cause a little bit more mechanical noise in the transformer, but isn't all that likely to cause electrical hum (which is what hum you hear coming from the speakers would be). However, IF there was DC offset on your power circuits, then the CMX-2 would eliminate it (and it's a lot less than 399 pounds). Ok but is there a version on CMX-2 that works in Sweden? Different plugs and voltage here.. If the transformer is not causing the electrical hum then I'm not sure what the problem is. Either my unit is faulty or it's within spec. Like I said it doesn't bother me that much atm but I'm afraid it will with my new speakers. And also it feels like a sperate amp that is considered to be one of the best should be more quiet then my bugdet receiver. |
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