Gain in mixed balanced-unblanced environnement, how to not end up with noise through the speakers

[ora2j]

Hello everyone, long time ASR lurker and first time poster here.

Ive been in a bit of a pickle lately with my setup.

I recently went out and bought myself a Yamaha DME24N to replace EQAPO which did my filtering straight on my PC. And so far, tinkering with DME designer it seems like it's doing exactly what i want, which is good.

Now, the thing is, my main source for everything is a PC going through HDMI to a Denon AVR-3808. Which means i only get unblanced pre-outs, and even at -20db volume, the DME isn't even picking up a signal on the front panel indicators. Audio does go through, but it looks completely muted if you only looked at the meters.

I then tried to mess with the input gain control of the DME, and i don't know if mine is broken or if they are really like that, but setting anything other than 10 (default, lowest value, highest is -60) is so noisy that it's unlistenable. With the gain set at -4, the overall volume is correct, but you can totally hear the noise over what's currently going through the speakers.

Speaking of speakers, they're Klipsch Heresy II, driven by a t.amp S75 (that thing too doesn't even light it's signal indicators). So very high sensitivity, and a pretty ill-suited amp (soon to be replaced and relegated for surrounds, which are much less sensitive KEF Q55) which means that the slightest bit of noise goes through and is amplified by the horns.

To summarize for the front channels : PC HDMI (Always max volume) --> AVR (should be the thing that manages volume) --> DME24N (filtering, EQ, TC, Limiters) --> T.amp S75.

Now, i have tried some stuff like using a Tascam LA-80 to convert the -10dbv to +4dbu signal and convert from unbalanced RCA to balanced XLR, but that changed basically nothing and introduced ground loops.

So i'm here in search of tips on how would i go about this the proper way ?

Do i need somthing like a pre-amp on my pre-outs to go in the DME with a much hotter signal ? Do i need a different less noisy amp (which would not solve the issue of noise on the DME inputs ?) or is there a device i don't know about which is made for this exact situation ?

Happy to give out more info and measurments if needed.

TIA for any clues !

 

[solderdude]

Are all settings correct in the DME24N.
Is it connected/wired properly ?
Is RCA out to balanced in done correctly ?

 

[JayGilb]

Check that the DME is configured to use internal word clock. Have you tried other i/o channels on the DME ?

 

[ora2j]

Are all settings correct in the DME24N.
Is it connected/wired properly ?
Is RCA out to balanced in done correctly ?

What to you mean by correct settings ? Input gain, Word Clock ?

It should be wired properly AFAIK

I made the cables myself by cutting the ends of RCA cables i had lying around, With - and gnd shorted at the euroblock end with a small jumper cable. i'm waiting on better cable i ordered to make proper interconnects, which i hope improves this noise issue.

 

[ora2j]

Check that the DME is configured to use internal word clock. Have you tried other i/o channels on the DME ?

DME is set on 48khz internal word clock. I did check on multiple I/o channels (tho not all of them) and noise was the same on all of them.

 

[solderdude]

What to you mean by correct settings ? Input gain, Word Clock ?

It should be wired properly AFAIK

I made the cables myself by cutting the ends of RCA cables i had lying around, With - and gnd shorted at the euroblock end with a small jumper cable. i'm waiting on better cable i ordered to make proper interconnects, which i hope improves this noise issue.

Did you connect both pin 1 and 3 on the xlr input to ground ?

 

[ora2j]

Did you connect both pin 1 and 3 on the xlr input to ground ?

It's euroblock. But yeah, "-" and ground are connected together.

Well, i wanted to take a pic of the connector, but trying to pull it out the + cable snapped. So definitely pretty crap wire lol.
Ill try again next week when i get the better cable. I had them like this :

 

[JayGilb]

The inputs can be set to use microphone level signals and also have phantom power turned on, make sure these settings are correct.

 

[ora2j]

The inputs can be set to use microphone level signals and also have phantom power turned on, make sure these settings are correct.

Double checked it but i had already disabled 48v phantom power, so that's not it.

 

[solderdude]

What 'noise' are you hearing ?

 

[Waveform Fidelity]

Hello everyone, long time ASR lurker and first time poster here.

Ive been in a bit of a pickle lately with my setup.

I recently went out and bought myself a Yamaha DME24N to replace EQAPO which did my filtering straight on my PC. And so far, tinkering with DME designer it seems like it's doing exactly what i want, which is good.

Now, the thing is, my main source for everything is a PC going through HDMI to a Denon AVR-3808. Which means i only get unblanced pre-outs, and even at -20db volume, the DME isn't even picking up a signal on the front panel indicators. Audio does go through, but it looks completely muted if you only looked at the meters.

I then tried to mess with the input gain control of the DME, and i don't know if mine is broken or if they are really like that, but setting anything other than 10 (default, lowest value, highest is -60) is so noisy that it's unlistenable. With the gain set at -4, the overall volume is correct, but you can totally hear the noise over what's currently going through the speakers.

Speaking of speakers, they're Klipsch Heresy II, driven by a t.amp S75 (that thing too doesn't even light it's signal indicators). So very high sensitivity, and a pretty ill-suited amp (soon to be replaced and relegated for surrounds, which are much less sensitive KEF Q55) which means that the slightest bit of noise goes through and is amplified by the horns.

To summarize for the front channels : PC HDMI (Always max volume) --> AVR (should be the thing that manages volume) --> DME24N (filtering, EQ, TC, Limiters) --> T.amp S75.

Now, i have tried some stuff like using a Tascam LA-80 to convert the -10dbv to +4dbu signal and convert from unbalanced RCA to balanced XLR, but that changed basically nothing and introduced ground loops.

So i'm here in search of tips on how would i go about this the proper way ?

Do i need somthing like a pre-amp on my pre-outs to go in the DME with a much hotter signal ? Do i need a different less noisy amp (which would not solve the issue of noise on the DME inputs ?) or is there a device i don't know about which is made for this exact situation ?

Happy to give out more info and measurments if needed.

TIA for any clues !

You should not get ground loops with the TASCAM LA-80 - you can lift the grounds with the ground lift switch. Also remember that there is a gain trimmer on the front panel/gain switch on the rear - so that gives you a very large range of adjustment.

 

[ora2j]

What 'noise' are you hearing ?

Sounds EMIish, kinda like pitched up pink noise.

And while trying to record it, turns out it's coming from my PC since when it's turned off or when i unplug the HDMI cable from the AVR while the DME is plugged in, the noise stops. I bought some cheap LC fiber hdmi adapters to see if that cures it.

You should not get ground loops with the TASCAM LA-80 - you can lift the grounds with the ground lift switch. Also remember that there is a gain trimmer on the front panel/gain switch on the rear - so that gives you a very large range of adjustment.

True, i had forgotten to try this when i did a quick test with it, ill try again next week when i get all the stuff i need to make proper cables, which should arrive soon

But clearly, i was looking at the wrong thing to pinpoint the noise

 

[JayGilb]

Might be a group loop. PC graphics cards are notorious for introducing a whiny noise.
Sometimes connecting all components to the same outlet can help.

 

[ora2j]

Sometimes connecting all components to the same outlet can help.

Well, everything's on a single rack PDU, so that's not it.

 

[Waveform Fidelity]

Sounds EMIish, kinda like pitched up pink noise.

And while trying to record it, turns out it's coming from my PC since when it's turned off or when i unplug the HDMI cable from the AVR while the DME is plugged in, the noise stops. I bought some cheap LC fiber hdmi adapters to see if that cures it.


True, i had forgotten to try this when i did a quick test with it, ill try again next week when i get all the stuff i need to make proper cables, which should arrive soon
View attachment 555364

But clearly, i was looking at the wrong thing to pinpoint the noise

If its noise like then it is probably thermal noise, so somewhere in your the replay chain you have gains set too high and levels too low. If its ground loops its going to be power line hum

 

[ora2j]

If its noise like then it is probably thermal noise, so somewhere in your the replay chain you have gains set too high and levels too low. If its ground loops its going to be power line hum

It definitely sounds like when you'd have gain set wayyy too high on an amp and hearing hiss on the speakers. The thing for that noise to appear i only need to have my PC and the DME plugged into my AVR. Even if the signal doesn't go through the DME, the noise is still there, coming out of the AVR's pre out and into my power amp.

So i guess ground loop it is, but i've neved had one so bad.

 

[Michou]

Hello everyone, long time ASR lurker and first time poster here.

Ive been in a bit of a pickle lately with my setup.

I recently went out and bought myself a Yamaha DME24N to replace EQAPO which did my filtering straight on my PC. And so far, tinkering with DME designer it seems like it's doing exactly what i want, which is good.

Now, the thing is, my main source for everything is a PC going through HDMI to a Denon AVR-3808. Which means i only get unblanced pre-outs, and even at -20db volume, the DME isn't even picking up a signal on the front panel indicators. Audio does go through, but it looks completely muted if you only looked at the meters.

I then tried to mess with the input gain control of the DME, and i don't know if mine is broken or if they are really like that, but setting anything other than 10 (default, lowest value, highest is -60) is so noisy that it's unlistenable. With the gain set at -4, the overall volume is correct, but you can totally hear the noise over what's currently going through the speakers.

Speaking of speakers, they're Klipsch Heresy II, driven by a t.amp S75 (that thing too doesn't even light it's signal indicators). So very high sensitivity, and a pretty ill-suited amp (soon to be replaced and relegated for surrounds, which are much less sensitive KEF Q55) which means that the slightest bit of noise goes through and is amplified by the horns.

To summarize for the front channels : PC HDMI (Always max volume) --> AVR (should be the thing that manages volume) --> DME24N (filtering, EQ, TC, Limiters) --> T.amp S75.

Now, i have tried some stuff like using a Tascam LA-80 to convert the -10dbv to +4dbu signal and convert from unbalanced RCA to balanced XLR, but that changed basically nothing and introduced ground loops.

So i'm here in search of tips on how would i go about this the proper way ?

Do i need somthing like a pre-amp on my pre-outs to go in the DME with a much hotter signal ? Do i need a different less noisy amp (which would not solve the issue of noise on the DME inputs ?) or is there a device i don't know about which is made for this exact situation ?

Happy to give out more info and measurments if needed.

TIA for any clues !

Is the PC a laptop with an external PSU brick? If so, it might be worth trying a ground eliminator adapter (ground-lift adapter) on the PSU power plug, i.e. one of those 3-pin-to-2-pin polarized grounding converters, and seeing if that makes any difference.

Even with a double-insulated/Class II laptop PSU, the PSU can still provide an AC/common-mode path through its EMI capacitors, and depending on how the rest of the system is grounded, this can contribute to a ground-loop-type problem.

Another possibility is simply a gain-staging issue somewhere in the chain. It might be worth checking the nominal operating levels and gain structure of the AVR >> DME24N >> power amp carefully, rather than compensating for a low level at one point by adding gain at the DME input.

Given the sensitivity of the Heresy IIs, I'd definitely try the ground eliminator as a diagnostic. If the noise changes or disappears with it in place, that would point toward a grounding issue rather than the DME24N simply having an inherently noisy input stage.

Given the sensitivity of the Heresy IIs, I'd definitely try the ground eliminator as a diagnostic. If the noise changes or disappears with it in place, that would point toward a grounding issue rather than the DME24N simply having an inherently noisy input stage.

 

[ora2j]

Is the PC a laptop with an external PSU brick? If so, it might be worth trying a ground eliminator adapter (ground-lift adapter) on the PSU power plug, i.e. one of those 3-pin-to-2-pin polarized grounding converters, and seeing if that makes any difference.

Even with a double-insulated/Class II laptop PSU, the PSU can still provide an AC/common-mode path through its EMI capacitors, and depending on how the rest of the system is grounded, this can contribute to a ground-loop-type problem.

Another possibility is simply a gain-staging issue somewhere in the chain. It might be worth checking the nominal operating levels and gain structure of the AVR >> DME24N >> power amp carefully, rather than compensating for a low level at one point by adding gain at the DME input.

Given the sensitivity of the Heresy IIs, I'd definitely try the ground eliminator as a diagnostic. If the noise changes or disappears with it in place, that would point toward a grounding issue rather than the DME24N simply having an inherently noisy input stage.

Given the sensitivity of the Heresy IIs, I'd definitely try the ground eliminator as a diagnostic. If the noise changes or disappears with it in place, that would point toward a grounding issue rather than the DME24N simply having an inherently noisy input stage.

PC is a tower with a Corsair RM850X, so a pretty good, high end PSU. Ground eliminator is a big no-no here since it's drawing quite a lot of power and i don't want any potential failure to fry the whole computer instead of just the PSU. I tried with a USB-C docking station instead of my GPU, and noise was the same.

I can't change the gain on the AVR obviously, the best i can do is a +12db offset on the volume to compensate for the other channels, but that's it. On the DME, input gain is set at the minimum since when i tried to get it up, the noise was much more noticeable. On the Power Amp, i have both gain knobs at 0 attenuation.

Again, since i managed to pinpoint the HDMI issue, i got an optical HDMI adapter which sould arrive in the next few days, with it the PC and AVR should be completely electrically isolated.

 

[ora2j]

Well, i finally got the parts and made better cables for my stuff. I got my HDMI Optical adapter which did help a ton, but still, the signal coming into the DME is wayyy too low, which means i have to run my amps at max gain, which can be heard also in the speakers.

I though about using an 8 channel preamp to get a hotter signal to the DME, but I've yet to find 1u options that would also convert from RCA to balanced out. Do such devices even exist ? For now, i have to use my receiver at -20db to even get a slight signal on the DME (Like -60db on the meters...) and the signal indicators still haven't lit up on the front panel.