White Noise Question

[metaldaze]

After fixing a ground loop that was made very apparent once I upgraded my cables I discovered something that I can't seem to figure out. I was trying to see if the hum I was hearing changed with volume, which it didn't. However while toying around after fixing the loop I found that with no input signal to the Pre-Amp (Integra Reciever) and the volume turned up close to max (85 out of 100), white noise began coming out of the speakers. After 90 it was to a point it was loud enough to be clearly heard from my listening position. Is this the noise floor from my pre-amp?  Some other opinions thought it was my amp clipping.. an XPA 4 Gen 3, which I find hard to believe. Again the speakers are connected but there isn't any input signal, so my thinking is that there is no load on the amp to cause clipping. Any ideas? Thanks a lot. Trying to see if I should replace/upgrade my Receiver since it's still under warranty.

[Casey Leedom]

Sounds like the completely expected noise floor of your preamplifier. My guess is that if you had any actual material playing with the volume knob up that high you'd probably have blood coming out of your ears ...

And it's definitely not your amplifier clipping. It can drive your speakers considerably louder than the noise you were hearing.

It could be induced noise on the cables between your preamplifier and amplifier, but unless it's 60/120Hz, that's probably not what you're hearing. I.e. if it really is wide-spectrum "white noise", it's probably just thermal noise in the preamplifier electronics.

Casey

[klinemj]

Can you post a recording of the sound?

Mark

[hemster]

I agree with klinemj , let's hear the sound so we can offer informed suggestions.

[metaldaze]

Ok will do, let me try to now. Thanks for the replies!

[metaldaze]

Ok I've attached a 15 second mp3 of the white noise. I also discovered while doing this recording it only appears to happen when the receiver is set to analog RCA input such as my turntable or tape deck. My computer is hooked up via HDMI & when I switch over to my PC input the speakers are dead quiet. The noise also increases if I turn on my TT's phono-stage (cambridge CP1) so that adds to it but wasn't on during the recording. 

Attachments:

2017_11_28_19_29_36_1.mp3 (214.69 KB)

[klinemj]

How far away from speakers were you recording? And, I presume the first few seconds were you ramping up the volume. When you say the noise increases when you go to TT's phono stage...same noise but louder or different noise?

What are the speakers?

Frankly, from what I do here and what you say about the HDMI and PC inputs - its certainly not the amp clipping (didn't think it would be). And it certainly doesn't sound like a hum due to a multiple of the power source frequency. Sounds like...noise. If its that loud more than a few feet away from the speaker - it certainly doesn't sound right...unless your speakers are bloody efficient and turning up the volume that loud would take the slightest noise and make it really loud. If you try to listen at this pre-amp level...do your ears bleed?

Do you have access to any other preamp, even if it's something you can borrow to test your RCA inputs?

Mark

[metaldaze]

Yes that's exactly right. I was actually recording about 6'' from the speaker so really close. When I turn on the phono stage its complimented a little more but mostly just discernible noise from the stage itself. Flip it off and it goes back to that sound which I attached. The speakers are factory upgraded Ohm Acoustics model H on front, and 2 pairs stacked & wired in parallel factory upgraded Ohm Acoustics model C2's on the rear channel. They're all 88db sensitive, fairly average.

I agree and when i upgraded to red river cables it exposed that issue which i was able to fix. It does get quite loud at 90 and above up to 100 from my listening position which is ~9ft from each speaker; but as you pointed out yes my ears would be bleeding. I've had it up to 76? & that was veryy loud. And i live in an apartment so thats about all its going to get.

I don't have access to another pre-amp but this one does actually emit hum from the receiver itself. I called the dealer i bought it from & they suggested I bring it in to see if it needs to be replaced. That is my next move but in the meantime I've been trying to reach out for some opinions. Its an Integra DRX-3 for reference

Cheers! Ian

[socketman]

White noise, thats what i call the ol lady

[metaldaze]

 Well played. She could say the same for me when I talk about this stuff Lol 

[Casey Leedom]

By the way, if you're experiencing white noise when you have your Pono Input selected and crank the volume up, I'm completely unsurprised. The signal levels coming in on the Phono Input are Really Low. I think you could get them to twitch just by cursing ... (not really, but you get the idea). The Tape Input is a bit odder since that should be running at standard interconnect levels.

Regardless, it's very telling that you don't hear anything with an HDMI input. I think that you're just listening to your preamplifiers RCA Analogue Input Buffers.

Casey

[klinemj]

Nov 28, 2017 20:34:32 GMT -5 metaldaze said:

Yes that's exactly right. I was actually recording about 6'' from the speaker so really close. When I turn on the phono stage its complimented a little more but mostly just discernible noise from the stage itself. Flip it off and it goes back to that sound which I attached. The speakers are factory upgraded Ohm Acoustics model H on front, and 2 pairs stacked & wired in parallel factory upgraded Ohm Acoustics model C2's on the rear channel. They're all 88db sensitive, fairly average.

I agree and when i upgraded to red river cables it exposed that issue which i was able to fix. It does get quite loud at 90 and above up to 100 from my listening position which is ~9ft from each speaker; but as you pointed out yes my ears would be bleeding. I've had it up to 76? & that was veryy loud. And i live in an apartment so thats about all its going to get.

I don't have access to another pre-amp but this one does actually emit hum from the receiver itself. I called the dealer i bought it from & they suggested I bring it in to see if it needs to be replaced. That is my next move but in the meantime I've been trying to reach out for some opinions. Its an Integra DRX-3 for reference

Cheers! Ian

If you set the preamp volume where you normally listen (not at these extreme levels you don't listen at)...I presume you barely have even a hiss. If so - then don't worry about it because it's not a true practical issue. And, if the noise is the same on the phono stage but just louder - then yep...what Casey says. If it were something different, then could be an issue either within the cable from the TT to preamp or in a connector.

Mark

[metaldaze]

Thanks for the replies, nice to bounce stuff off and put the mind at ease. Casey now that I think about it I believe I was mistaken- the tape inputs were quiet as well so you are right about that. I didn't even think about it just being the phono level input causing it as expected. And yes Mark at normal to a little above average listening levels there's no white noise @ my listening position, and with music its loud enough for my environment being wary of the neighbors.

Since the phono stage is fairly nice and well reviewed I'm going to stick with it for now. The outputs from the TT are permanent (AT LP-120USB) but I do need to upgrade the interconnects from the stage to the receiver. There's no ground wire from the TT, but the CP1 has a prong for a ground wire as does the receiver since it has a phono input as well. Maybe grounding the phono stage to the receiver even though it's entering as line level through another RCA jack would help the noise. I guess it can't hurt to try. Thanks again everyone it's much appreciated!

[Casey Leedom]

As I noted, the signal coming out of your Turntable Cartridge is Very Low. For a Moving Magnet Cartridge I think the signal levels are in the 3-6mV range and a Moiving Coil Cartridge is often less than 1mV. Contrast this with the standard interconnect levels around 2V. A “Phono Input” is specially designed to take these very low Cartridge signals and amplify them into the range used in the rest of the system. (And you need to properly select “MM” or “MC” to match the Cartridge in use.)

Because these Turntable Cartridge signals are so low, it’s really important that Care is taken to prevent induced signals, etc. in the signal path.

Casey

[metaldaze]

Right & that is understood. I do think the CP1 sounds better still when compared to the phono input on the receiver but I didn't take into account any added noise. The connects I'm using now are very entry level so its time they got an upgrade since the cables to my amp are now AQ. But then the TT is next..  then upgrading my Walsh 2's. It doesn't end haha 

[Axis]

You are going to get some hiss in life and audio. Finding the cure has been that long strange trip we take.

[Casey Leedom]

Have you made sure that the Phono Input is properly selected to MM/MC for the type of cartridge you have?

Casey

[klinemj]

Nov 29, 2017 9:24:28 GMT -5 metaldaze said:

Thanks for the replies, nice to bounce stuff off and put the mind at ease. Casey now that I think about it I believe I was mistaken- the tape inputs were quiet as well so you are right about that. I didn't even think about it just being the phono level input causing it as expected. And yes Mark at normal to a little above average listening levels there's no white noise @ my listening position, and with music its loud enough for my environment being wary of the neighbors.

Since the phono stage is fairly nice and well reviewed I'm going to stick with it for now. The outputs from the TT are permanent (AT LP-120USB) but I do need to upgrade the interconnects from the stage to the receiver. There's no ground wire from the TT, but the CP1 has a prong for a ground wire as does the receiver since it has a phono input as well. Maybe grounding the phono stage to the receiver even though it's entering as line level through another RCA jack would help the noise. I guess it can't hurt to try. Thanks again everyone it's much appreciated!

Sometimes, the connections to the cartridge itself may be a little loose. That can cause some noise, but it's usually a hum and not the white noise you had. So, if the TT is just white noise...it's not that.

Mark

[Casey Leedom]

Yeah, I don't think it's the Turntable or the Cartridge. It sounds like the Phono Preamplifier, combined with the Preamplifier, combined with the Amplifier s boosting insanely low-level signals through a multi-level gain structure and the result is simple thermal/electronics/input buffer noise showing up as White Noise. And, as far as I know, metaldaze hasn't even said if there is a Turntable/Cartridge even connected ...

Casey

[klinemj]

I just assumed he did...maybe not a good assumption!

Mark