Phono Hum

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IslandPink
No idea why I do this anymore
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Re: Phono Hum

Post by IslandPink » Sun Jul 07, 2019 8:07 pm

Just got the phono back in playing and it's MUCH better. I can only hear some hum quite close to the bass units now. Bass and lower mids have improved, of course !
What a relief after putting up with it for so long.
Just playing 'Don Juan's reckless daughter', as you'd expect.
I also took the opportunity to drill some holes and double-up on output RCA's, it was a bit of a faff, but now the phono is 2-channel-ready :
Phono_extra.JPG
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

little eddy
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Re: Phono Hum

Post by little eddy » Mon Jul 08, 2019 4:16 pm

I see the mechanical isolation, and remember MJ having some ideas in this. Wondering if the maglev units might be a novel option and not too expensive if can keep the weight down?
TD-125/RB250/MC25FL & 'Snail' phono, NAS/SBT with CS4398 DAC, 41MP pre & MoFo Power, still messing with OBs.

little eddy
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Posts: 625
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Location: Manchester

Re: Phono Hum

Post by little eddy » Mon Jul 08, 2019 4:33 pm

I see the mechanical isolation, and remember MJ having some ideas in this. Wondering if the maglev units might be a novel option and not too expensive if can keep the weight down?
TD-125/RB250/MC25FL & 'Snail' phono, NAS/SBT with CS4398 DAC, 41MP pre & MoFo Power, still messing with OBs.

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IslandPink
No idea why I do this anymore
Posts: 6956
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

Re: Phono Hum

Post by IslandPink » Mon Jul 08, 2019 6:36 pm

I wouldn't recommend what I did, that's for sure ! It was a desperation measure for hum which at that time turned out to be a broken earth wire down the centre of the circuit.
Maglev sounds very novel indeed :shock:
My next phono intends to have some of the valves soft-mounted using 'well-nuts' ( M3 ) in oversized holes to allow some reduction in vibration.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

little eddy
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Posts: 625
Joined: Sun Nov 09, 2008 2:06 pm
Location: Manchester

Re: Phono Hum

Post by little eddy » Mon Jul 08, 2019 9:02 pm

How microphonic might the d3a be - it sounds like you think this may not have been necessary?
TD-125/RB250/MC25FL & 'Snail' phono, NAS/SBT with CS4398 DAC, 41MP pre & MoFo Power, still messing with OBs.

User avatar
IslandPink
No idea why I do this anymore
Posts: 6956
Joined: Tue May 29, 2007 7:01 pm
Location: Denbigh, N.Wales

Re: Phono Hum

Post by IslandPink » Mon Jul 08, 2019 9:38 pm

Not bad. Nick uses them in the Reference.
Soft mounting might help a bit - Nick has them in an enclosed box, unlike me.
I have some B&Q tube dampers - didn't put them back on yet, will check. But at present it's just residual hum that's the only audible thing.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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