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Post by pedrocols on Jun 11, 2017 12:26:45 GMT -5
SNR on these amps are not great to begin with. However, if both amps are causing the hiss it could potentially be something else.
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Post by leonski on Jun 11, 2017 15:57:27 GMT -5
Yes, I get it about 'pins'. How much CURRENT can your outlet sink into these amps? If you have both plugged into a 15 amp circuit with other stuff, than you might as well have a couple XPA-1L amps for all the good that 'extra' power is doing you.
Hiss MIGHT be coming from the speaker itself with some interaction with the amp. Don't forget that 'Stats 'plug in' and have that high polarizing voltage.
'Stats are also NOT the easiest load, even given the good sensitivity rating. They are typically HIGHLY reactive over maybe 10khz and use lots of power while having some very crazy electrical characteristics.
Any way to borrow another amp from the dealer for an afternoon? What amp were they shown with?
OOOPS! My Bad. The motion 40 is of 'conventional' design without a plug-in PS. However, the sensitivity is listed for 2.83 volts which is 2 watts at the 4 ohms nominal impedance. If checked at the more correct 2 volts for 4 ohms, the sensitivity would be LOWER. I don't know if that matters.
the tweeter is similar to the original AMT designs now used by a number of manufacturers, since the patent has run out. EMO uses one, Radio Shack DID use one and several others.
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"HISSSS"
Jun 12, 2017 3:27:59 GMT -5
via mobile
Post by kiwiemo on Jun 12, 2017 3:27:59 GMT -5
This is odd...is it a hiss or a hum? Can you record a video and share it so we can here it? Mark It's a hiss, no humm or buzz, it increases when you turn the dial up(no source connected) just speaker to amp, amp to power. But when music is on, it is there and way more pronounced with vocals. Not that able to get a recording on me oldy iPhone 4s sorry Kiwiemo |
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"HISSSS"
Jun 12, 2017 3:45:50 GMT -5
via mobile
Post by kiwiemo on Jun 12, 2017 3:45:50 GMT -5
Yes, I get it about 'pins'. How much CURRENT can your outlet sink into these amps? If you have both plugged into a 15 amp circuit with other stuff, than you might as well have a couple XPA-1L amps for all the good that 'extra' power is doing you. Hiss MIGHT be coming from the speaker itself with some interaction with the amp. Don't forget that 'Stats 'plug in' and have that high polarizing voltage. 'Stats are also NOT the easiest load, even given the good sensitivity rating. They are typically HIGHLY reactive over maybe 10khz and use lots of power while having some very crazy electrical characteristics. Any way to borrow another amp from the dealer for an afternoon? What amp were they shown with? OOOPS! My Bad. The motion 40 is of 'conventional' design without a plug-in PS. However, the sensitivity is listed for 2.83 volts which is 2 watts at the 4 ohms nominal impedance. If checked at the more correct 2 volts for 4 ohms, the sensitivity would be LOWER. I don't know if that matters. the tweeter is similar to the original AMT designs now used by a number of manufacturers, since the patent has run out. EMO uses one, Radio Shack DID use one and several others. [ These amps are getting a full 15 amps, there is nothing else running on the line, the plan was to run two 20amp lines from the switchboard, but would bottleneck with the 16amp ISOTEK power cables, it's not so easy to find 20amp iec cables. All that said, is that where the hiss is coming from, not enough juice? I have an old(18yrs) or so, AVR which has netted the same hiss. Sooo back to the OP, would a power conditioner make this go away?? I have to confess, I got these speakers sight unseen, as they were cheap enough to be able to sell on and not run a great loss. They were a stop gap till I either fixed my KEF or replaced with the same. Money is bit of a hold back to doing things all at the same time. Kiwiemo |
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KeithL
Administrator 
Posts: 10,261
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Post by KeithL on Jun 12, 2017 8:56:26 GMT -5
You've already explained what's going in in perfect detail already.... "its not with every CD" What you're hearing is simply the background noise on the recording. The amount of background noise varies considerably between different CDs... and most are pretty low... but there's always background noise. (If it was any sort of problem with the amp - or the speakers - it would be there all the time.) Your Martin Logans are simply somewhat brighter than the KEFs - at the frequencies where hiss is most audible. (They could be more efficient at those frequencies, or could be coupling energy at those frequencies more efficiently into the room.) KEFs are known to be somewhat "laid back"... meaning that, in a real room, they probably have a slightly rolled-off high end. Remember that, if you have two different speakers, of the same efficiency, both rated at +/- 3 dB over some frequency range, they can still be 6 dB different at any given frequency in that range. While there is some merit to some of the other suggestions..... For example, a noisy AC line can SOMETIMES raise the noise floor...... The noise you're talking about obviously depends on the source itself..... Brighter speakers make hiss tend to be more audible - sometimes significantly. (But, then, you're also hearing more details in the music.) Sooo, since my last issue, of killing a pair of KEF R900's, I got down on a deal from a local Martian Logan dealer and have set up a pair of motion 40's. These speakers run a sensitivity of 92db.... Where as the KEF were running 90db....as far as specs go the rest is much of a muchness, although I wouldn't put the two on the same level, as I see it. The issue here is the XPA-1 monos noise floor is far more audible with the ML 40s. The hiss was there with the KEFs but very very low, as in not heard in the music. Totally different situation with the ML40s that said its not with every CD. Can this issue be 'reduced' with a power conditioner? Any help/information would be great Cheers Kiwiemo |
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"HISSSS"
Jun 12, 2017 19:26:27 GMT -5
via mobile
Post by kiwiemo on Jun 12, 2017 19:26:27 GMT -5
You've already explained what's going in in perfect detail already.... "its not with every CD" What you're hearing is simply the background noise on the recording. The amount of background noise varies considerably between different CDs... and most are pretty low... but there's always background noise. (If it was any sort of problem with the amp - or the speakers - it would be there all the time.) Your Martin Logans are simply somewhat brighter than the KEFs - at the frequencies where hiss is most audible. (They could be more efficient at those frequencies, or could be coupling energy at those frequencies more efficiently into the room.) KEFs are known to be somewhat "laid back"... meaning that, in a real room, they probably have a slightly rolled-off high end. Remember that, if you have two different speakers, of the same efficiency, both rated at +/- 3 dB over some frequency range, they can still be 6 dB different at any given frequency in that range. While there is some merit to some of the other suggestions..... For example, a noisy AC line can SOMETIMES raise the noise floor...... The noise you're talking about obviously depends on the source itself..... Brighter speakers make hiss tend to be more audible - sometimes significantly. (But, then, you're also hearing more details in the music.) Sooo, since my last issue, of killing a pair of KEF R900's, I got down on a deal from a local Martian Logan dealer and have set up a pair of motion 40's. These speakers run a sensitivity of 92db.... Where as the KEF were running 90db....as far as specs go the rest is much of a muchness, although I wouldn't put the two on the same level, as I see it. The issue here is the XPA-1 monos noise floor is far more audible with the ML 40s. The hiss was there with the KEFs but very very low, as in not heard in the music. Totally different situation with the ML40s that said its not with every CD. Can this issue be 'reduced' with a power conditioner? Any help/information would be great Cheers Kiwiemo Cheers KeithL The sad part is I never really got to enjoy the KEF R900's, before the uniQ issue, and as it is I'm not at all enjoying the ML40's. The journey will continue.... Kiwiemo. |
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Post by leonski on Jun 13, 2017 13:01:57 GMT -5
What amp did you hear the MLs demo'd with? Can you Borrow that amp for 1/2 a day?
If as likely, the speakers run a little 'hot' in the high end, why'd you buy them?
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