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Old 1st April 2013, 06:08 AM   #301
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The amps are Joule Electra Stargate SET Monos, and sorry, yes Lighter Note. I had one with a multiple inputs which I sold and currently have another that's just a single input. Both Lighter Notes sounds fantastic except for the hum. When I hook up an active preamp, no hum. My system is vinyl only so there's a phono preamp (Dynavector P75) going into the Lighter Note. I was told by the builder of my Lighter Note that when you connect regular "active" preamps they have their own ground than runs from plug earth connector all the way to rca connector ground, so whenever you connect it to the amp, even without a source, the connection is already grounded. The Lighter Note does not provide signal ground, it passes whatever ground comes from the source. Is this the same with the Warpspeed?
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Old 1st April 2013, 09:25 AM   #302
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There's a couple of guys over on the hub.Audiogon.com (Identify this hum, please) that are talking about this very same thing - Minorl, Atmasphere, etc.

The Warpspeed has the very same signal path setup as the LighterNote - the series resistor followed by the shunt resistor to signal gnd - no connection whatsoever to any chassis earth power supply earth or anything - it's like having a volume pot just stuck in the middle of your Interconnects cables - the variable resistors of the LDRs are completely isolated so the earth loop problem (assuming that's what it is) is something to do with the earth connection of the source phono preamp &/or the power amps from the brief look I had.

It also sounds like your Stargate's have their central 0 volt point of the actice circuitry tied directly to the chassis earth - nothing wrong with that but it does tend to magnify any ground loop problems and there's easy ways of getting around this problem (seperating central 0volt point from chassis earth via 10 Ohm thermistor, diodes plus resistors, etc) but not sure if the simple mods will void any gaurantee/insurance.

The same thing works for any component using mains power - for a phono preamp, particularly if it's a good one, it's a 100 ohm resistor to separate the chassis earth from the preamp central 0volt point (usually in the power supply between the power caps)

Another thing to check with Uriah's LighterNote is that the impedance setting can easily be changed and you need to know if this has been setup for your Stargate's input impedance, and from a Review, I gather this varies from 20kR (SE) to 50kR (PP mode) - so this will need to be addressed properly too - this is the advantage of the LighterNote design, and it's well worth investigating it.

I too, use a WarpSpeed in my system and it doesn't have the LighterNote flexibility but it is quite a bit more tolerant of load resistances.

Neither units present any problems with 'hum' or 'ground loops', and wouldn't expect them too, if properly built.

'hope this is of some use to you ...
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Old 1st April 2013, 09:26 AM   #303
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Ground loop(s) somewhere between your components? Not having the same exact system as yours I can only speculate the cause, but a good place to start is with your interconnects and power cords with safety ground. There are articles on how to hunt for these loops and they're better at explaining. Here are examples: https://www.passdiy.com/project/articles/ground-loops and How To Fix Turntable Hum: The Most Common Turntable Problem | Best Turntables

Being battery operated, the W'speed's signal ground is separate from the battery (-) ground. Being off the grid might help to break a ground loop between your phono preamp and power amplifier.

There are several W'speed owners on heavy daily dosage of vinyl but I have not heard from any of them of any hum issues. Here's one -check out his shelves of vinyl -just half of his collection!: Enjoy life with LP's and Turntables: Have you ever thought of a "45/45 rpm" dual pulley for Rega?
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Old 1st April 2013, 09:29 AM   #304
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Thanks for chiming in, James...it's my bedtime though.
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Old 1st April 2013, 11:15 AM   #305
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No problemo! Good to pass on any good news.

Not much progress with the other projects - everything is on "go slow" at present.
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Old 1st April 2013, 03:32 PM   #306
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That's what I was hoping, that having a battery operated unit might break the ground loop but unfortunately it's one of those trial and error things. I have a Bottlehead kit here that's battery operated that I may just have to go ahead and build to try out that theory. I've swapped all the interconnects and lifted all the grounds one at a time and that's what isolated the Lighter Note as being the problem. An active preamp solves the problem but the difference in sound quality is pretty startling. My wife had a sad look on her face when the Hagerman Clarinet was in the system because even she could hear the difference.

Thanks so much for the help.
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Old 1st April 2013, 04:35 PM   #307
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The only way the LighterNote could create this ground loop is if the guy that built it has mistakenly added a chassis ground connection via the phono plugs or the output pcb circuitry - if there is a connection (simple check with multimeter), it shouldn't be there and just remove it. (This is the signal plugs for the interconnect, not the chassis earth)

I repeat this for emphasis, that there shouldn't be any ground or chassis connection between the signal interconnects and the earthed chassis, and the LighterNote shouldn't be the source of any ground loop at all.

Also, please check that the phono plugs themselves are isolated from the metal chassis - this could have been missed in the build.

Apart from that, there really isn't much else to go wrong - there just the 4 resistors part of the LDRs that are connected top the signal path - the Leds themselves don't carry any hum, or low freq anything, across to the photo-sensitive resistors.

It's a bit of a puzzle why you're having this problem.

However, Alan's battery power system of the WarpSpeed will certainly make sure there's nothing at all connected to the mains, so pretty much guaranteed no source of ground loops there either, and the ready built construction will make sure it's built to specs.

Either units are well worth perservering with if the improvement in clarity, detail and transparency suits your system - there's nothing quite like it anywhere else and you just have to make sure your source's output impedances (of the phono preamp) is low enough not to cause problems - the amp's 20 -> 50kR is okay, IMO.
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Old 1st April 2013, 05:43 PM   #308
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Ok. Very interesting. Alan, is there a way to reach you off board so I can get some particulars about the Warpspeed?
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Old 1st April 2013, 07:21 PM   #309
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I would prefer by email... afdflores at msn dot com. Thanks!
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Old 2nd April 2013, 07:30 AM   #310
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Hey James, did you get a chance to play with your headphones...?
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