JDS Labs Atom Phono - love but 1 issue

[ccrnnr9@]

First post here but been lurking awhile. I've been on the hunt for a good phono pre-amp to run with my setup and feed into a V3 I purchased. I purchased a handful of different phono stages and thought I'd settled on one until JDS Labs released the atom phono. Having the tone controls is something I want and the quality of their products and service seems well regarded. In short I love it - up until receiving the Atom on Saturday I'd been pretty happy with the Pluto 2 and had also had nice results with the V3 Pro & Mani 2 fed into my V3.

The issue is the Atom has a very significant hum that I'm hoping is the result of a flawed or damaged unit as I'd love to keep this setup for numerous reasons. Any idea what could cause this on my end if it's not an issue with the unit? All other factors being equal all the other phono amps + my vintage cr-600 are all some degree of very quiet. The turntable is a technics sl-1700 - old but never given me issues. Running a technics 270c cartridge and where possibly working with phono pre amps set to 39-40db gain per KAD calculator to match the ideal setting for my cartridge. I'm at a lot what could cause this when all the others haven't run into that issue. Thoughts?

 

[staticV3]

Hi @ccrnnr9@! Welcome to ASR.

Is your turntable grounded to the Atom Phono?

They make RCA cables specifically for this purpose:

 

[ccrnnr9@]

Yes it's just the wired ground from the Technics - thing is no issues with the other 3 models listed above that I bought. I spoke with folks at JDS and they've been wonderful and want to send a replacement to test.

 

[cgallery]

What preamp and power amp are you using?

If your entire chain uses DC adapters, then you may need to introduce a connection to actual earth somewhere, perhaps from the phono preamp's ground lug to a receptacle cover screw.

 

[ccrnnr9@]

The complete setup is listed in the original post. The Atom Phono is the phono preamp (Technics feeds & grounds directly to that). The power amp is a Fosi V3. I've tried moving the ground plug per your thoughts with no results change. I'm hoping it's just an issue with the unit that arrived in shipping. They are very nice to work with and the unit is very well made/high quality.

 

[cgallery]

The complete setup is listed in the original post. The Atom Phono is the phono preamp (Technics feeds & grounds directly to that). The power amp is a Fosi V3. I've tried moving the ground plug per your thoughts with no results change. I'm hoping it's just an issue with the unit that arrived in shipping. They are very nice to work with and the unit is very well made/high quality.

You don't want to MOVE the existing ground wire from the turntable, but rather ADD a second ground wire from the receptacle cover plate screw to the same lug.

What you're missing is any true Earth connection, because all your gear uses DC power supplies.

 

[Emulator II]

In my case I was able to get rid of the hum by installing an additional ground wire from the phono pre to the amplifier. Maybe give this a try?

 

[ccrnnr9@]

You don't want to MOVE the existing ground wire from the turntable, but rather ADD a second ground wire from the receptacle cover plate screw to the same lug.

What you're missing is any true Earth connection, because all your gear uses DC power supplies.

I see - when you say receptacle cover plate screw I assume you're meaning the power amp (second ground wire from the phono ground lug to a cover plate screw on the power amp) as @Emulator II is also suggesting?

 

[cgallery]

I see - when you say receptacle cover plate screw I assume you're meaning the power amp (second ground wire from the phono ground lug to a cover plate screw on the power amp) as @Emulator II is also suggesting?

No, because your amplifier's case isn't earthed, either, as it is fed by an external DC power supply.

The cover plate screw is the screw that holds the (typically) plastic cover plate onto the wall receptacle (a.k.a. "outlet") that powers your gear. This screw should provide continuity to earth via your home's electrical system.

What I'm suggesting will provide the equiv. of the kit below, but just requires a wire and doesn't cost $30. Though the kit below may be a little easier for many people to install.

Amazon.com

 

[ccrnnr9@]

Ah I got it - thank you!

 

[antcollinet]

I see - when you say receptacle cover plate screw I assume you're meaning the power amp (second ground wire from the phono ground lug to a cover plate screw on the power amp) as @Emulator II is also suggesting?

I have a similar situation with my turntable, and have eliminated nearly all the noise by running a ground wire from the phono preamp ground terminal to a ground connection in an electrical socket.

If you do this take great care to ensure you are connecting to ground and not live or neutral. I removed the live/neutral pins on the plug to be sure - we can do that in the UK.

 

[ccrnnr9@]

Thanks for all the information y'all. Any idea why only this model would be running into this when the T3 Pro and Pluto 2 are both exceptionally quiet with no feedback?

 

[antcollinet]

Thanks for all the information y'all. Any idea why only this model would be running into this when the T3 Pro and Pluto 2 are both exceptionally quiet with no feedback?

Earthing is tricky - especially when you are working with signals in the region of 0.005V - or lower for MC cartridges - combined with high gain (x1000 and up) preamps. Minor differences in the way gear is connected up (internally or externally) can make a big difference.

It may be that in a different set up, your new turntable would be fine, and the others which are fine now would have issues. My turntable didn't need the earth wire with a previous amp/preamp combo.

 

[cgallery]

Thanks for all the information y'all. Any idea why only this model would be running into this when the T3 Pro and Pluto 2 are both exceptionally quiet with no feedback?

The response above is spot-on, the only thing I'll add is that photo preamp designs vary quite a bit on how signal ground and earth ground are handled/combined. I wouldn't consider this a knock on the JDS unit compared to the others you've tried, just a distinction. You may find that after adding another wire as discussed, it is actually the quietest phono stage you've tried.

 

[ccrnnr9@]

Ya I'll test the replacement unit as the unit I received had a loose ground wire connection upon arrival. Additionally I'll try the ground method listed above and report back. If this issue can be resolved I think the atom phono is a clear keeper for me for numerous reasons, build quality alone is superb. The Pluto 2 is a nice unit though.

 

[ccrnnr9@]

Replacement unit arrived today and simply swapping the original for the replacement immediately solved the problems. Just to make sure I wasn't crazy I went ahead and swapped back to the original and the problem was immediately audible even at moderate listening levels. Very glad this problem resolved itself. I'm still eager to have more time with the Atom and have a more realistic comparison with the Pluto 2. Can't say enough good things about communicating w/ John @ JDS - one of the main reasons I prefer to spend a bit more and work with a small company based here - the human connection is very much appreciated. I just wish they made a suitable power amp I could pair with the Atom - perhaps that will come in time. Thanks to all for the help!

 

[Mulder]

I have been considering this phono-amp for purchase. I have tried to find info about the case, but didn´t find any. It is aluminum or plastic?

 

[ccrnnr9@]

I have been considering this phono-amp for purchase. I have tried to find info about the case, but didn´t find any. It is aluminum or plastic?

It's aluminum and very well built. I have not tried the offering form iFi but have tried most of the other phono pre amps sub $200 and this one is my favorite. The Pluto 2 was really wonderful too but I wish it had an on/off switch and for my tastes, the tone controls are a nice touch. As an added bonus JDS labs are great to work with and make a quality product with great customer service.

 

[Mulder]

It's aluminum and very well built. I have not tried the offering form iFi but have tried most of the other phono pre amps sub $200 and this one is my favorite. The Pluto 2 was really wonderful too but I wish it had an on/off switch and for my tastes, the tone controls are a nice touch. As an added bonus JDS labs are great to work with and make a quality product with great customer service.

To my knowledge all products from JDS labs are very good build quality and excellent audio quality. These days I only buy products tested here or by other reliable websites. JDS labs phono-amp has not been tested anywhere, to my knowledge, but they are an exception in my view since they have a very good history of excellent products, so I trust they would not offer anything else than a very good phono-amp on the market.

 

[ccrnnr9@]

They really are. The only reason I've considered selling my Atom Phono is I recently got an amp with built in phono stage that sounds quite nice, albeit not as nuanced/detailed as the Atom. It's something I can notice slightly (I believe) A/B in non controlled settings but not sure I would notice long term without it. It's such a nice piece of equipment that I don't want to see it go. I wish they made more equipment aimed at analog folks as my digital equipment needs are pretty minimal.