Noise floor has increased

Aural Robert · 1728

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Offline Aural Robert

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on: February 06, 2018, 04:20:39 PM
I've been putting a fair number of hours in lately listening to vinyl as well as digitizing my collection.

Last weekend I was spinning Apostrophe (the song from the album of the same name) and got the BeePre to 0 on the coarse and -6 on the fine. When I lifted the needle I was surprised to hear a lot of white noise coming out of the speakers. I don't typically play it quite so loud and of course when the music is playing you don't hear it at all. But I know it's there now and I can hear it in the headphones and on quieter passages too.

Which tube or tubes are the culprits here? It is the tubes, right?

All advice is appreciated. I have some budget $$ atm so could pop for something nice if it's worth it. Thanks to all in advance.

Aural Robert
... His little feet got long 'n flexible ...

Origin Live Calypso TT w String Theory arm & Shure V15VxMR, Eros or BH DAC -> BeePre -> MonAmor 2A3s w JJ's => Blumestein Bamboo Tritons on Blumenstein Bamboo stands, AND Enhanced SEX w Sexy spkrs and subs in the WAF zone. DIY Belden 89259 w Eichmann interconnects throughout

Offline Paul Joppa

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Reply #1 on: February 06, 2018, 05:15:12 PM
Do you know the cartridge output level spec? That will help us figure out how bad the issue is, and whether a cart with more output would help.

As usual, it's worthwhile to check the voltages; problems there might point to some other cause.

Paul Joppa

Offline Aural Robert

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Reply #2 on: February 07, 2018, 02:47:04 AM
It's a Grado Platinum. I'll have to dig around and pull out the specs. But maybe it's not a big deal atm as I have a big change coming soon.

I've purchased a Woody tonearm from Pete Riggle and it's due to arrive before the end of the month, at which time I'll be changing out the Grado and mounting a Shure V15VxMR - which is 3mV. Once I have the installation dialed in I'll crank the volume again and give a listen and report back.

Thanks Paul.

Origin Live Calypso TT w String Theory arm & Shure V15VxMR, Eros or BH DAC -> BeePre -> MonAmor 2A3s w JJ's => Blumestein Bamboo Tritons on Blumenstein Bamboo stands, AND Enhanced SEX w Sexy spkrs and subs in the WAF zone. DIY Belden 89259 w Eichmann interconnects throughout

Offline kgoss

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Reply #3 on: February 07, 2018, 03:40:33 AM
Do you only hear the noise on the phono input with the BeePre volume maxed?  If it's on other inputs and in both channels I'd check the Paramount hum pots just to rule them out.

Ken Goss

Offline Paul Birkeland

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Reply #4 on: February 07, 2018, 03:58:01 AM
It would also be a good idea to plug some shorting plugs into the inputs of the Eros and then checking the noise floor.

There is a little tube rush in the Eros circuit, but it's so far below the music that it's generally very hard to hear. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Paul Joppa

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Reply #5 on: February 07, 2018, 07:34:39 AM
There seem to be more than one Grado Platinum. I found two examples, one rated 5mV and the other 0.5mV. If these are not typos, and you're using a 0.5mV cartridge, then that's probably the whole problem and a 3mV cart would reduce the noise in use by 16dB. But if you're using a 5mV cart, the noise with the 3mV will be louder by 4dB.

Paul Joppa

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