Attempting to solve hum on p80/s300

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Ageagainstthemachine
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Attempting to solve hum on p80/s300

Unread post by Ageagainstthemachine »

I'm hoping someone will be able to help..

I've noticed hum on all inputs (including those not in use) on my p80 with the exception of cd input which is connected to my dac...

If the volume is at minimum or maximum the hum disappears and its dead silent (tdk pot)

It doesn't matter if all inputs are disconnected (including the built in phono rca's and power supply) from the preamp.

I'm wondering now if the phono board is somehow causing the issue or if its the amp or possibly noise from the mains..

Can someone advise if its safe to power up the amp while connected to the speakers but not to the pre amp please?
NVA S300 - P80 (TDK 2CP-2511 pot ELMA selector switch) Audiolab 6000CDT - Topping D30 DAC - Project Debut Carbon DC with Ortofon 2M Blue - P80 Phono Stage - Technics RS-BX646 Cassette Deck (with tube buffer to up the low output) - Speakers are either modified Monacor Katana Open Baffle or Kralk Audio MK2 BC30 with PAW stands - most cables are NVA - Various sound treatment

Geoff.R.G
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Re: Attempting to solve hum on p80/s300

Unread post by Geoff.R.G »

Yes, it is safe
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Ageagainstthemachine (Thu Aug 31, 2023 10:01 pm)

TheMarlin
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Re: Attempting to solve hum on p80/s300

Unread post by TheMarlin »

Do you have a switching power supply somewhere plugged into the mains connection to your amp. A noisy wallwart can ruin your noise floor.

I have my power amplifier and DAC running from one run from the mains, and everything else running from a different run from the mains. That keeps the noise down. When I had everything running on one, was noisy as hell.

Other alternative is maybe get an NVA BMU. That’ll provide a clean electrical signal and reduce noise.
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Ageagainstthemachine (Thu Aug 31, 2023 10:01 pm)
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Ageagainstthemachine
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Re: Attempting to solve hum on p80/s300

Unread post by Ageagainstthemachine »

Thanks. I use a Topping D30 which I think has a switching power supply. I will have to check tomorrow to see if its on the same block as the amp. Its funny, when the dac is selected the hum disappears at min and max volume. I will have to disconnect it completely from the mains to see if it helps, so far I've only disconnected the rca's. I also tried to run an earth from the volume pot but it made no difference.
NVA S300 - P80 (TDK 2CP-2511 pot ELMA selector switch) Audiolab 6000CDT - Topping D30 DAC - Project Debut Carbon DC with Ortofon 2M Blue - P80 Phono Stage - Technics RS-BX646 Cassette Deck (with tube buffer to up the low output) - Speakers are either modified Monacor Katana Open Baffle or Kralk Audio MK2 BC30 with PAW stands - most cables are NVA - Various sound treatment

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Re: Attempting to solve hum on p80/s300

Unread post by Fretless »

Could the cables running from P80 to power amps be picking up some interference? Are there any mains cables close to them?

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Ageagainstthemachine
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Re: Attempting to solve hum on p80/s300

Unread post by Ageagainstthemachine »

Fretless wrote: Thu Aug 31, 2023 10:38 pm Could the cables running from P80 to power amps be picking up some interference? Are there any mains cables close to them?
Yeah unfortunately there is a lot of cables lurking behind the gear and I'm really limited for space
NVA S300 - P80 (TDK 2CP-2511 pot ELMA selector switch) Audiolab 6000CDT - Topping D30 DAC - Project Debut Carbon DC with Ortofon 2M Blue - P80 Phono Stage - Technics RS-BX646 Cassette Deck (with tube buffer to up the low output) - Speakers are either modified Monacor Katana Open Baffle or Kralk Audio MK2 BC30 with PAW stands - most cables are NVA - Various sound treatment

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Re: Attempting to solve hum on p80/s300

Unread post by Fretless »

Try to get mains cables away from interconnects and speaker leads. See if that helps.
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Ageagainstthemachine (Fri Sep 01, 2023 12:38 am) • TheMarlin (Fri Sep 01, 2023 8:17 am)

Upstairs:
Vinyl
Pro-Ject 1.2 + Grado Sig Jr + Cambridge Alva Duo
DigiVolumio PC + Kiss DP-500 + Sabaj A20d
NVA: Cube2 + LS6+ Sabaj A10a (2) + Little Bear MC2
Downstairs:
Vinyl
Logic DM101 + Syrinx LE1 + Grado Sig MCX
DigiDenafrips Ares II + Volumio PC + Cambridge CXC
NVA: P50 (phono)Aiyima A07 MAX (2) + Arcam One
HP: Allo DigiOne + Sabaj A10d + AQ NightOwl
Office: Allo DigiOne SIG + SMSL M300se + Douk G4 (x2)
Mission 760 + Monolith 887 + German Maestro GMP 450

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Re: Attempting to solve hum on p80/s300

Unread post by Daniel Quinn »

My lenco ptp MK1 and home made naim clone phono amp introduced a lot of noise when playing phono. The power supply for the phono is two 500va transformers but it is located in the corner of room.

Nevertheless when not playing a record it was very noisy , there were lots of EMF and noise it was picking up .

When I built MK11 , I connected the earth wire from the mains lead at the turntable end to the motor .

It worked a treat , it's so silent now , I've abandoned plans to copper line the acrylic phono box .
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Latteman (Fri Sep 01, 2023 8:40 am) • Ageagainstthemachine (Fri Sep 01, 2023 10:58 am)

Ageagainstthemachine
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Re: Attempting to solve hum on p80/s300

Unread post by Ageagainstthemachine »

Thanks all for the replies.

I tried the amp this morning with just the speakers connected and no pre and I Unplugged both the TT and DAC power supply it was quieter, the main buzzy sort of hum has gone but I am left with a very quiet hum if I put my ear right next to the speaker.

I am wondering about making a BMU since I can't afford to buy one. I'm also wondering about DC Blockers such as that offered by Audiolab or more likely make my own with some research.

I can see myself doing more tests plugging and unplugging equipment to figure out causes... And if its definitely the switching power supplies I'll have to look at linear alternatives... Again, something I could make I suppose
NVA S300 - P80 (TDK 2CP-2511 pot ELMA selector switch) Audiolab 6000CDT - Topping D30 DAC - Project Debut Carbon DC with Ortofon 2M Blue - P80 Phono Stage - Technics RS-BX646 Cassette Deck (with tube buffer to up the low output) - Speakers are either modified Monacor Katana Open Baffle or Kralk Audio MK2 BC30 with PAW stands - most cables are NVA - Various sound treatment

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Re: Attempting to solve hum on p80/s300

Unread post by Fretless »

Slight hum with your ear right next to the speaker doesn't sound all that unusual.

If it is audible from your normal listening position - then I would be worried.
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Ageagainstthemachine (Fri Sep 01, 2023 7:38 pm)

Upstairs:
Vinyl
Pro-Ject 1.2 + Grado Sig Jr + Cambridge Alva Duo
DigiVolumio PC + Kiss DP-500 + Sabaj A20d
NVA: Cube2 + LS6+ Sabaj A10a (2) + Little Bear MC2
Downstairs:
Vinyl
Logic DM101 + Syrinx LE1 + Grado Sig MCX
DigiDenafrips Ares II + Volumio PC + Cambridge CXC
NVA: P50 (phono)Aiyima A07 MAX (2) + Arcam One
HP: Allo DigiOne + Sabaj A10d + AQ NightOwl
Office: Allo DigiOne SIG + SMSL M300se + Douk G4 (x2)
Mission 760 + Monolith 887 + German Maestro GMP 450

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