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Phono Preamp XLR Out Distortion

Dom Cobb

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Just purchased a used Gold Note PH-10 phono preamp and I’m having issues with distortion in both channels when using the XLR outs. RCA outs are perfect. The previous owner said he only ever used the RCAs and was unaware of a problem with the XLR outs.

I am using the same XLR cables that were in place with my prior Parasound phono preamp, and I haven't made any changed to my amp, power source, TT interconnects or cartridge. All variables are essentially constant with exception of the new phono stage which was swapped. I've also tried another set of XLRs to eliminate the possibility of bad cables. I can’t for the life of me understand what the problem would be.

Is it possible the balanced circuit could be bad?
 

Curvature

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Balanced outputs have +6dB gain. Try reducing it.

What you're hearing is probably clipping.
 

DVDdoug

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Is it possible the balanced circuit could be bad?
Yes, the balanced output probably uses a different chips/electronics.

It seems like an unusual failure to me. It's odd that both channels would develop the same defect/failure.

It's possible that it's a manufacturing error and it never worked...

If you open it up and there's a separate PC board for the balanced output maybe there is a power supply connector with a loose connection.

It's probably an easy repair, but of course skilled-specialized labor isn't cheap. I'm sure it will cost more to repair than to replace it with a less expensive preamp.*

You don't NEED a balanced connection unless you have noise problem that the balanced connection MIGHT fix. And if you "adapt" an unbalanced-output to a balanced-input you still get most of the advantages of balanced. (Going the other way from balanced-to-unbalanced doesn't always work properly.)



* It's often cheaper to build something new than to repair it. When things are built on an assembly line it doesn't take much labor, and it's unskilled or less-skilled labor. It often takes more labor to troubleshoot & repair, and it's skilled labor, and if it's not done at the factory any replacement parts have to sourced individually and often shipped individually, etc.
 

MaxwellsEq

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If you still have the Paramount, you can measure the voltage out of its XLRs and compare with the voltage out from the new Gold Note. I suspect @Curvature is right and the output is too hot for the next stage compared to your previous phono preamplifier.
 
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Dom Cobb

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Balanced outputs have +6dB gain. Try reducing it.

What you're hearing is probably clipping.
The Gold Note phono preamp is at it's lowest gain setting of -3 db which would equate to 42 db baseline, and there is still significant distortion. I took a short video for reference. The Gold Note manual doesn't reference a + 6 db for XLRs like the Parasound explicitly does; only a unbalanced RCA at 2V vs balanced XLR at 4V. I assume it's still the standard +6 db so 48 db with XLRs using the -3 db gain setting.

Also, I thought this was interesting - Even if I am playing the music through my RCA input, if the XLRs are plugged in, I have the distortion. Once I unplug them it's gone immediately. When playing through the XLR input it sounds the same as when I am playing through the RCA input with the XLRs plugged in.

If you still have the Paramount, you can measure the voltage out of its XLRs and compare with the voltage out from the new Gold Note. I suspect @Curvature is right and the output is too hot for the next stage compared to your previous phono preamplifier.
Sadly I sold it. I was using the default 40 db baseline settings for a MM cartridge (46 db with XLRs) with the Parasound ZPhono XRM and it sounded great.
 
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DVDdoug

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Also, I thought this was interesting - Even if I am playing the music through my RCA input, if the XLRs are plugged in, I have the distortion. Once I unplug them it's gone immediately.
Now, that's REALLY weird!!! Plugging into a balanced input shouldn't affect the signal at all.

So what are you plugging into? Is it an actual XLR input, or are there adapters?

Microphone inputs are low impedance and the low-impedance load could cause a problem, but I doubt you doing that. The high-gain of a mic input would also be a problem.

But again, there's no advantage to balanced connections if you don't have a problem. And in your case they are creating a problem!
 
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Dom Cobb

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Now, that's REALLY weird!!! Plugging into a balanced input shouldn't affect the signal at all.

So what are you plugging into? Is it an actual XLR input, or are there adapters?

Microphone inputs are low impedance and the low-impedance load could cause a problem, but I doubt you doing that. The high-gain of a mic input would also be a problem.

But again, there's no advantage to balanced connections if you don't have a problem. And in your case they are creating a problem!
Yup totally strange the XLRs are causing distortion in the playback when I'm playing through the RCA input on my integrated (Cambridge Audio EVO 150 which has XLR inputs).
 

sergeauckland

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Yup totally strange the XLRs are causing distortion in the playback when I'm playing through the RCA input on my integrated (Cambridge Audio EVO 150 which has XLR inputs).
Not strange if the XLR output is going into an RCA input. It depends on how the balanced output is configured, i.e. fully floating or centre-tapped, and which pins of the XLR go to where on the RCA.

If that's configured wrongly, you can short out one half of the balanced output, which is very likely to cause distortion, and possible damage to the balanced output. The safest way is to connect XLR pin 2 to RCA pin, and XLR pin 1 to RCA screen, leaving XLR pin 3 unconnected.

S
 
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Dom Cobb

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Not strange if the XLR output is going into an RCA input. It depends on how the balanced output is configured, i.e. fully floating or centre-tapped, and which pins of the XLR go to where on the RCA.

If that's configured wrongly, you can short out one half of the balanced output, which is very likely to cause distortion, and possible damage to the balanced output. The safest way is to connect XLR pin 2 to RCA pin, and XLR pin 1 to RCA screen, leaving XLR pin 3 unconnected.

S
Not sure if I'm following. I'm using a 3 pin male XLR to 3 pin female XLR to connect my Cambridge Audio EVO 150 to the Gold Note PH-10 (and previously my Parasound ZPhono XRM).
 

sergeauckland

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Not sure if I'm following. I'm using a 3 pin male XLR to 3 pin female XLR to connect my Cambridge Audio EVO 150 to the Gold Note PH-10 (and previously my Parasound ZPhono XRM).
Nor am I now!

I took this:-
Yup totally strange the XLRs are causing distortion in the playback when I'm playing through the RCA input on my integrated (Cambridge Audio EVO 150 which has XLR inputs).

to mean that you were going from XLR to RCA.

If you're going XLR to XLR and getting distortion, then as others have said above, I'd be suspicious of the XLR output being faulty.

S
 
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Dom Cobb

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Sorry I know that was a little confusing. Let me try it another way.

I thought it was strange that when I have the source on my Integrated selected to Analog In and using RCA to RCA, I'm picking up distortion if the XLR cable is plugged in but not but XLR is not selected as the source. I.e. I have both the RCAs and XLRs plugged into the Integrated and Phono preamp simultaneously. In short, if the XLR cables are connected I am picking up serious distortion.
 

sergeauckland

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Sorry I know that was a little confusing. Let me try it another way.

I thought it was strange that when I have the source on my Integrated selected to Analog In and using RCA to RCA, I'm picking up distortion if the XLR cable is plugged in but not but XLR is not selected as the source. I.e. I have both the RCAs and XLRs plugged into the Integrated and Phono preamp simultaneously. In short, if the XLR cables are connected I am picking up serious distortion.
OK, do you get distortion on RCA to RCA without the XLRs plugged in?
Do you get distortion XLR to XLR without the RCAs plugged in, or only when both are plugged in?

If only when both, then the reason for this is likely to be the way the RCA outputs are derived, as per my first reply. The equipment is unlikely to be designed for both to be connected at the same time.

If it's not that, then don't know, it could be a fault which would need a tech to look into.

S
 
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Dom Cobb

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OK, do you get distortion on RCA to RCA without the XLRs plugged in?
Do you get distortion XLR to XLR without the RCAs plugged in, or only when both are plugged in?

If only when both, then the reason for this is likely to be the way the RCA outputs are derived, as per my first reply. The equipment is unlikely to be designed for both to be connected at the same time.

If it's not that, then don't know, it could be a fault which would need a tech to look into.

S
No distortion when I’m using RCA to RCA and the XLRs aren’t plugged in.

Yes I get distortion when I’m using XLR to XLR and the RCAs aren’t plugged in. This is the same level of distortion I pick up when I’m using RCA to RCA but the XLRs are also plugged in (and not being utilized).
 

sergeauckland

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No distortion when I’m using RCA to RCA and the XLRs aren’t plugged in.

Yes I get distortion when I’m using XLR to XLR and the RCAs aren’t plugged in. This is the same level of distortion I pick up when I’m using RCA to RCA but the XLRs are also plugged in (and not being utilized).
Looks very much like a fault in the balanced XLR output circuitry. Odd that it affects both channels, but if the two XLR channels are built, for example using a 4 opamp chip, then that would affect both channels. Anyway, I don't think it's something that can be diagnosed remotely, it'll need to go on a test bench.

Best of luck
S
 
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Dom Cobb

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Looks very much like a fault in the balanced XLR output circuitry. Odd that it affects both channels, but if the two XLR channels are built, for example using a 4 opamp chip, then that would affect both channels. Anyway, I don't think it's something that can be diagnosed remotely, it'll need to go on a test bench.

Best of luck
S
Thank you! Appreciate the feedback.
 

JP

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What are you plugging it in to? I see a report on the RME forum from another person having issues with the XLR output being too hot.
 
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Dom Cobb

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What are you plugging it in to? I see a report on the RME forum from another person having issues with the XLR output being too hot.
I’m plugging into the XLR input on my Cambridge Audio EVO 150 integrated. Could you share the link please?
 
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JP

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The person on the RME thread seems rather confused about gain, so not that helpful.
 
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Dom Cobb

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The person on the RME thread seems rather confused about gain, so not that helpful.
Interesting point on the Cambridge thread. Says the EVO 150 input sensitivity is 1.5 V. The Gold Note PH-10 references 2 V when using the RCAs vs 4 V when using the XLRs. Overloading is likely the problem huh.
 

JP

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Says the EVO 150 input sensitivity is 1.5 V.

No, it said Cambridge uses 1.5V for their amps. There's no listed spec for max input for the EVO.
 
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