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Hum from Phono Stage (Yaqin Tube)

sxty8goats

sxty8goats

Super Member
So..

I finally broke down and picked up a phono stage. Mainly out of curiosity and with a hope that I'd get a bit stronger signal to my receiver. Yamaha, the built in phono-stage is @ 20% quieter than the rest of the system.

Now here is my issue. If I turn the amp up with the built in phono stage, it is silent until I reach @ -1. This is loud. On normal sources, CD / TV I typically don't raise the volume past -15. (the max is +5, min down @ -70)

With the Yaqin tube phono-stage, I get a noticeable hum @ - 25 that only increases with volume. I get this with the turntable disconnected or connected. Grounded or not. I've run the ground from the table back to the receiver, I've run it to the phono-stage.

Is this typical for a tube pre? The manual mentions a hum at high volume but this is a bit more than I'm happy with.
 
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G'day mate, I can't recall if this applies to that particular phono stage, but many hum issues with other similar units were/ are traceable to the wall wart supplied.

A better quality wall wart will possibly help presuming your unit has a wall wart power supply. One thing to check anyway. Regards, Felix aka catman.
 
G'day mate, ok then another possibility is physical position of the phono stage as induced hum pickup is possible.

Try moving the phono stage around to see if the level of hum pick up changes. Regards, Felix aka catman.
 
j_sunne said:
Any CFLs or dimmers on the same circuit?
Click to expand...

No, just a lot of gear and a modem and wireless router.

I didnt' have a chance to move it around last night. I'll have to try that.

It seems to have the hum with the unit turned off and the cables connected between the phono-stage and the receiver. It seem like a muted version of touching the ends of the interconnects. This without the TT being connected to the PS.
 
I have a MS12-B and it's silent, always been silent except for when I rolled in some NOS RCA 12au7's. If the TT is grounded to it, sounds like a tube to me. I didn't even try mine with the stock tubes as I heard you can do much better. BTW I do find it sensitive to vibrations and have it on a foam block with o-rings around the tubes. Hope this helps, nice piece of kit IMHO.
 
The modem and WiFi router may be the problem, even computers connected to the same circuit can cause all sorts of electrical noise/interference, I would move the router and modem or any other computer hardware to another outlet/circuit, and check to see if the hum is still there.
If the phono stage is new, I doubt the caps are bad, but then again who knows?

John
 
Just an update, minor one at that. I wasn't home much at all this past weekend so I didn't have time to try any of your suggestions. I have a plan to follow so that I can be methodical and see if I can isolate the issue.

The bit that has me most concerned is that I seem to get the hum even with the unit powered off and connected to the receiver, with and without the TT connected to the phono stage. This will be the first thing that I confirm when I get a chance to trouble shoot. First starting with the power cord disconnected, moving on from there.
 
If it hums with the thing switched off, I'd have to lean towards the cables between the amp and the phono stage, or a ground loop caused by the grounded power cord on the phono stage. Swap cables, or use one of those cheater adapter things to lift the ground to see if anything changes.
 
Had a hum like this with a Yaqin phono pre, drove me nuts for a while, turned out to be an old and almost broken headshell lead. Swapped them out and all was well. I'll echo the comments above. If nothing else works, try a power supply cleaner like a Panamax. The more sensitive your gear gets, the better it sounds. The tradeoff is that you have to be more careful about every aspect of it. A power supply issue that wasn't noticeable before could become hugely apparent.
 
jgordon said:
Had a hum like this with a Yaqin phono pre, drove me nuts for a while, turned out to be an old and almost broken headshell lead. Swapped them out and all was well. I'll echo the comments above. If nothing else works, try a power supply cleaner like a Panamax. The more sensitive your gear gets, the better it sounds. The tradeoff is that you have to be more careful about every aspect of it. A power supply issue that wasn't noticeable before could become hugely apparent.
Click to expand...

It is brand new :) or maybe :(

The TT is only a few months old, I bought it for myself for X-mas. Project Debut III. She doesn't show any hum through the receiver's phono pre.
 
My point was that if there are issues in your electrical supply, they might become more apparent through the tube stage than in your phono in. More sensitive amps will show weaknesses wherever they may be. And as much as it might not be fun to hear, the newness of the table is no guarantee of soundness of parts.

What happens when you plug a cd player or other line stage input into the pre? With and without the TT plugged into the phono in? Hum still present?
 
Have had slight hum issues with the MS-12B; resolved with swapping ICs about and a dose of feng shui. Seriously, altering the orientation of the unit caused or reduced hum. Also, have definitely found some valves to be quieter than others.
 
From my experiences I would try a few different brand cables and lengths 1st then swap tubes 2nd.

My SS phono pre is silent til 4 oclock but my tube one starts to hum at 1:30 oclock. I never listen over 10:30 so no problem NOW. With one pair of tubes I can hear radio signals
 
sxty8goats , you ever get to the Bottom of your Hum problem ? i just bought one of these & sure enough same Exact problem with mine humming like this ..... I'm wondering if buying new tubes is gonna help ..
 
I tried swapping out the Tubes to some Sovteks i had in one of my guitar amps , Same Hum problem.

I have tried it all , new cables , grounding it out , different power places/strips to plug it in , Other turntables & stereos , different locations ....
Think mine is gonna head back to Hong kong unless they give the Okay to take it appart & see what may be the probem inside ....
They say they will pay return postage , i just feel bad as it's about $60 to ship one of these .
 
With my experience I can see many probable places which can be looked upon.

  1. If your mains earth ground is connected to chassis and same time phono's analog ground is also somehow connected to earth ground and chassis then you get this issue.
    Remedy: Connect mains earth ground to chassis but separate audio ground by isolating it from chassis and earth ground. Now put connection like this
    earth-f4.gif
  2. If PS does not have good filter to remove ripple then this could happen.
    Remedy: Use C-R-C filter on the output of rectifier with C >=4700uF (voltage rating as per requirement)and R=1ohm,2W (wattage as per requirement).
  3. Ground wire from TT arm to phono is not connected to clean ground inside phono.
    Remedy: Internal connection of tonearm ground wire is connected to output of PS DC ground. in above diagram zero volt line refers that.

PS: CFL and proximity of SMPS can add buzz to sound, IMO hum is different.
 
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I recently bought a MS-22b phono amp and was experiencing quite a bit of hum. Besides relocating the unit itself, I've found that repositioning the power, ground, input and output cables at the back of the unit make a huge difference in the amount of hum.
Some of these wires want to run along side of each other and others don't.
 
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