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Post by ralfwalter on Aug 12, 2017 9:03:09 GMT -5
Hi all!
I've been enjoying my setup for quite some time now. I'm running a very modest system- XSP-1 preamp and A-300 amp with polk towers. I recently turned things up a bit on the system and when my record was done I heard some hum. While trying to debug I ended up unplugging the phono inputs completely and the phono channel has a static-like (pink noise?) sound. of course it's more audible the more I turn up the volume. However - switching to another input channel yields zero sound (dead quiet) so that leads me to believe the phono stage is noisy. Is that normal for the XSP-1? I am considering a dedicated phonostage to help me work through this but now that I can hear it it'll always bug me. Any insights are greatly appreciated!
Ralf
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Post by novisnick on Aug 12, 2017 9:30:23 GMT -5
Welcome ralfwalter , so glad your here. Best forum on the net. The XSP-1 is a wonderful preamp. Ive owned both generations. It always helps to post your gear preferably in your signature. Most likely your Turntable is the culprit, they can be very finicky at time and for the smallest of reasons. Do you have access to another TT? I realize most don't but it would make diagnosis much quicker. |
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Post by DavidR on Aug 12, 2017 9:33:06 GMT -5
It may not be the Pre-amp phono stage. Is the ground still connected? Are the RCA cables the issue? Cartridge?, etc.
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Post by ralfwalter on Aug 12, 2017 10:08:34 GMT -5
It may not be the Pre-amp phono stage. Is the ground still connected? Are the RCA cables the issue? Cartridge?, etc. As I mentioned - I hear the noise even with the TT unplugged entirely. it is sound that comes from the phono channel even with nothing plugged in. I just now tested switching from MM to MC and it's quiet again but since I have a MM TT that won't do. Again - nothing plugged in - still getting noise.  Thanks! |
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Post by ralfwalter on Aug 12, 2017 10:13:53 GMT -5
Welcome ralfwalter , so glad your here. Best forum on the net. The XSP-1 is a wonderful preamp. Ive owned both generations. It always helps to post your gear preferably in your signature. Most likely your Turntable is the culprit, they can be very finicky at time and for the smallest of reasons. Do you have access to another TT? I realize most don't but it would make diagnosis much quicker. Thanks for the signature tip. I've just added my info. Surely it'll change with time.  So yeah my TT is not even plugged in to the XSP-1. I get the noise with it set at MM and the volume up quite a bit. If I switch to MC nothing but that won't do since I have MM turntable. Again - nothing plugged into the phono inputs but getting some noise. Thanks! |
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Post by novisnick on Aug 12, 2017 10:51:13 GMT -5
Welcome ralfwalter , so glad your here. Best forum on the net. The XSP-1 is a wonderful preamp. Ive owned both generations. It always helps to post your gear preferably in your signature. Most likely your Turntable is the culprit, they can be very finicky at time and for the smallest of reasons. Do you have access to another TT? I realize most don't but it would make diagnosis much quicker. Thanks for the signature tip. I've just added my info. Surely it'll change with time. So yeah my TT is not even plugged in to the XSP-1. I get the noise with it set at MM and the volume up quite a bit. If I switch to MC nothing but that won't do since I have MM turntable. Again - nothing plugged into the phono inputs but getting some noise. Thanks! I know Monday is a Looooonnngggggg time from now but give Emotiva a call first thing Monday morning and ask for tech help. They'll fix you up, hopefully you'll have it fixed before then! Good luck!👍👍🎶🎶 |
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Post by leonski on Aug 16, 2017 13:22:44 GMT -5
The phono section is the Highest Gain in your system. Any existing noise will be ruthlessly exposed.
I find it a little odd that MM is noisier than MC. MC is typically a very much lower voltage producer and needs more amplification which leads to more noise.
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KeithL
Administrator 
Posts: 10,273
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Post by KeithL on Aug 16, 2017 13:41:35 GMT -5
The output on a Moving Coil cartridge is abut 20 dB lower than that on a Moving Magnet cartridge. This means that the Moving Coil cartridge requires a lot more gain. However, the recommended load impedance for a Moving Coil cartridge is a lot lower. (The standard load for MM is 47 kOhms; loads for MC range from about 50 Ohms to 500 Ohms.) In certain types of circuitry with very low signal levels, the inherent noise of the circuit itself is related to the operating impedance, with less noise at lower impedances. While this isn't usually an issue with other types of audio circuitry, it is still important at the levels and impedances used by phono cartridges and inputs. In short, at the very low signal levels used by phono preamps, the noise benefit of operating at the lower impedance can become significant. Also, in specific circuit designs, the circuitry required to add that extra 20 dB of gain is actually so quiet that it reduces the overall noise rather than raising it. The phono section is the Highest Gain in your system. Any existing noise will be ruthlessly exposed. I find it a little odd that MM is noisier than MC. MC is typically a very much lower voltage producer and needs more amplification which leads to more noise. |
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Post by Gary Cook on Aug 16, 2017 16:19:18 GMT -5
My experience has been that phono stages in themselves aren't noisy, they don't actually create the noise. But they are extremely high gain on their own, then add normal pre amplification gain and then power amplification gain and the result can be noticeable, especially at higher than listenable volume settings. Having them open ended (no input) leaves them more susceptible to picking up anything electronically noisy in the local environment. Utilising a battery powered phono pre amp can help in some cases, but not always. It depends on the source of the noise, if it's getting in through the power supply then a battery power phono pre amp will help. If it's coming via RFI for example then it won't.
Cheers
Gary
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Post by leonski on Aug 16, 2017 18:42:43 GMT -5
My experience has been that phono stages in themselves aren't noisy, they don't actually create the noise. But they are extremely high gain on their own, then add normal pre amplification gain and then power amplification gain and the result can be noticeable, especially at higher than listenable volume settings. Having them open ended (no input) leaves them more susceptible to picking up anything electronically noisy in the local environment. Utilising a battery powered phono pre amp can help in some cases, but not always. It depends on the source of the noise, if it's getting in through the power supply then a battery power phono pre amp will help. If it's coming via RFI for example then it won't. Cheers Gary Input Shortin Plugs? Might that help? |
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Post by garbulky on Aug 16, 2017 19:00:38 GMT -5
Welcome ralfwalter , so glad your here. Best forum on the net. The XSP-1 is a wonderful preamp. Ive owned both generations. It always helps to post your gear preferably in your signature. Most likely your Turntable is the culprit, they can be very finicky at time and for the smallest of reasons. Do you have access to another TT? I realize most don't but it would make diagnosis much quicker. Thanks for the signature tip. I've just added my info. Surely it'll change with time. So yeah my TT is not even plugged in to the XSP-1. I get the noise with it set at MM and the volume up quite a bit. If I switch to MC nothing but that won't do since I have MM turntable. Again - nothing plugged into the phono inputs but getting some noise. Thanks! Aren't there two MM settings? |
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Post by leonski on Aug 16, 2017 22:37:41 GMT -5
With NOTHING plugged into the MM inputs, try some input shorting plugs.
Multiple MM settings would be for 'loading' and 'capacitance'.
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Thanks!
