If you are looking to ground loops you have to disconnect the units - not just turning then off. Otherwise the loop created by the signal cables grounds and/or ground wire of mains cables is still there.
Tube Power Supply Mechanical Hum - Tube Recommendations?
- Thread starter LL21
- Start date
If you are looking to ground loops you have to disconnect the units - not just turning then off. Otherwise the loop created by the signal cables grounds and/or ground wire of mains cables is still there.
so i disconnected/unplugged everything except DAC, pre and amp...hum still there. when i turn volume louder, it gets louder...which means it must be coming BEFORE the pre (hence the volume control can increase the hum). i think its the Zanden...let me try to get quieter tubes and see what happens. i think this is what happened last time...i cannot remember exactly. i guess i need to find quieter tubes...
Some alternative ways of diagnostic:
Do you have a pair of amplified computer speakers? If so, just buy a cheap RCA - jack adapter and connect them to your DAC output - if you still have the hum then it is due to the DAC, not to system ground loops.
Or better still get a EMU 0204 USB audio interface, a laptop and some spectral analysis program - much more reliable than listening to hums and not very difficult to use. As you have tube equipment it is very useful to check if performance of equipment is not being degraded by tube aging.
Do you have a pair of amplified computer speakers? If so, just buy a cheap RCA - jack adapter and connect them to your DAC output - if you still have the hum then it is due to the DAC, not to system ground loops.
Or better still get a EMU 0204 USB audio interface, a laptop and some spectral analysis program - much more reliable than listening to hums and not very difficult to use. As you have tube equipment it is very useful to check if performance of equipment is not being degraded by tube aging.
Hi microstrip. thanks for all your help!!! having disconnected and unplugged everything...it reallly has to be the Zanden. When i switch the main DAC off (but leave the power supply on)...the hum is still there...which i think narrows it down to the rectifier tubes. i have just replaced them and the hum is still there. i will try to get some different tubes and see what happens.
now as for the static noise..not the hum...you were right. it is a different problem. it disappears when i mute the pre...so it is the pre. quiet and does not increase with volume...so probably just the natural noise floor of the preamp.
now as for the static noise..not the hum...you were right. it is a different problem. it disappears when i mute the pre...so it is the pre. quiet and does not increase with volume...so probably just the natural noise floor of the preamp.
i spoke with Audio Exotics Hong Kong, the distributor for Zanden in Asia...they confirmed change the rectifier tubes...perhaps my "back up" tubes were also noisy. i have emailed Brent Jessee who sold both sets to me, and asked for his advice and help. will keep all posted...thanks.
OK...my initial conclusions: 1) All tubes have been replaced. 2) Cables redressed; 3) Power supply moved away from DAC; 4) all non-essential units unplugged...steady hum still coming thru the mid cones both sides. I identified that when the DAC PSU unit is on (but the DAC unit itself is off...the hum is not there.) This makes more sense...it is coming when the DAC unit is on. (changed that tube too...hum still there.)
I think this may have to do with the fact that the new preamp has a much lower noise floor...and now that i recall, when i tried a Shindo (signal to noise of 119db), i had a simliar noise...at the time, i was so focused on evaluating the Shindo, it just skipped my mind until today.
I expect to get some guidance from Zanden later this week. Hum is not terrible at ordinary levels, but if you have a Reference Recordings CD on (which you can generally turn up), the hum is there during quieter passages which is irritating. And when i play movies also at louder levels, same thing.
I think this may have to do with the fact that the new preamp has a much lower noise floor...and now that i recall, when i tried a Shindo (signal to noise of 119db), i had a simliar noise...at the time, i was so focused on evaluating the Shindo, it just skipped my mind until today.
I expect to get some guidance from Zanden later this week. Hum is not terrible at ordinary levels, but if you have a Reference Recordings CD on (which you can generally turn up), the hum is there during quieter passages which is irritating. And when i play movies also at louder levels, same thing.
lloyd,
You might have a ground issue with your Zanden. Have you swapped IC's? You might try that. Also, you could run a 14 ga wire between the Zanden and your preamp ground screw if it has one or attach the wire using the case screws on both units and see if it that eliminates the problem. You can use 2 spade connectors for the wire,solder or solderless type.
You can get a small roll of 14ga primary wire at your local hardware store. Or you may have a suitable insulated piece lying around.
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Hi Roger,
yes, i just swapped out all ICs...hum still there....maybe this is just living with tubed DAC? i can hear hum in dead quiet room at 30 of 99 on preamp volume...can definitely hear it at 45...but that is pretty loud...my neighbhors would start to complain as the pre has 25db of gain and the speakers are 95db sensitive. lets put it this way...if my Gryphon comes back fixed, i will live with this, given the quality of music i am getting (and frankly i am just plan tired of chasing this stuff...as long as it is not some indicator of lethal problems.)
yes, i just swapped out all ICs...hum still there....maybe this is just living with tubed DAC? i can hear hum in dead quiet room at 30 of 99 on preamp volume...can definitely hear it at 45...but that is pretty loud...my neighbhors would start to complain as the pre has 25db of gain and the speakers are 95db sensitive. lets put it this way...if my Gryphon comes back fixed, i will live with this, given the quality of music i am getting (and frankly i am just plan tired of chasing this stuff...as long as it is not some indicator of lethal problems.)
Hi lloyd,
I bet dollars to doughnuts you have a ground problem between your preamp and the Zanden, it probably effects your Gryphons also. It could be a very easy fix, you can run that 2 or 3 ft 14 ga wire between the Zanden and your preamp and it should fix the problem.
Every system should be dead quiet,mine is and my speakers are 96db efficient. If after you do this and the problem still continues I would try another DAC. Btw I use a Monarchy tube DAC and it is dead quiet,so it is not a "tube" problem as such. I think the Zanden ground scheme design could be a problem.
And while your at it,you might connect the two Zanden chassis together first with a short piece of 14 ga wire also. I would try that if the Zanden/preamp wire doesn't fix the problem. Run the wire connecting the Zanden DAC (where the IC's are)to the preamp.
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Lloyd
Do the problem come after you changed tubes ? and it does not happen before ? if you said that is a mechanical hum that should be the ring of the power transformer, if that happen after you change the tube , that could be new tube cause big current than the tube come with, then over the range of power transformer's limit and cap too, what you can try is put back those tube which come with the unit and see OK or not or you can change a bigger transformer and bigger cap to up grade it
tony ma
Roger - interesting...before i changed preamps a few wks ago (i still had this problem)...i hooked up a friends unshielded ICs between pre and amp...and all noise 100% disappeared. it was incredible...the theory at the time was grounding-related. I hooked up the same unshielded ICs between the new pre and the amp...and i've still got the problem.
before I electrocute myself...exactly where should i look on the back of the Zanden and the preamp to connect the wire? I see on the back of the preamp, a screw with an icon that looks like an old aerial tv antenna. On the back of the Zanden, there is no such screw icon...do i connect the wire between the antennae screw on the pre to just any screw on the Zanden DAC chassis? then, do i connect the same wire to any screw on the chassis of the Zanden power supply?
Lloyd,
You can use any chassis screw. You are only connecting a wire between both chassis. I have a many connected to my preamp chassis,it look like a birds nest. I have connected them while the system is on also. But you should do this while the system is off. I have never been shocked or had any problems. You are using the stock ground on your preamp and not bypassing anything. Another member (mep) had the same problem and this was the remedy.
Thanks, Roger. I presume this is a very thin thread-like wire you are suggesting? Like fishing line-thickness wire? i think you are suggest i slightly unscrew the grounding screw, wrap the wire around the screw a few times like thread and then tighten the screw back...and then do the same with the other end of the wire on any chassis screw on the Zanden...right?
Is there a transformer involved? If so, one thing I haven't seen mentioned is the possibility of some low level DC voltage getting to it.
Lloyd,
14 awg wire is 1.628 mm diameter. Make sure you use a piece of insulated wire and strip off about a 1/2 inch of the cover material. I prefer to use a solderless connector but it's not necessary. Try the grounding screw first and see how that works. Good luck!
The metric equivalent would be about 50/0.25 and is stranded wire.
Microstrip indirectly was hinting at this, and that there may be a ground loop issue/etc compounding this.
Lloyd you are in an apartment in the UK?
Could be transformer saturation by what your saying that is causing mechanical hum that seems to come from the power supply section of the product.
Problem is that if in an appartment this problem may be very intermittent or impossible to identify source.
One suggestion, take the gear (obviously not speakers though
)to a friends house that is not near the apartments and see what happens.Did this for my own mains issue and showed the product worked fine until brought home and had intermittent mains issue.
Microstrip indirectly was hinting at this, and that there may be a ground loop issue/etc compounding this.
Lloyd you are in an apartment in the UK?
Could be transformer saturation by what your saying that is causing mechanical hum that seems to come from the power supply section of the product.
Problem is that if in an appartment this problem may be very intermittent or impossible to identify source.
One suggestion, take the gear (obviously not speakers though
Did this for my own mains issue and showed the product worked fine until brought home and had intermittent mains issue.
Orb/Microstrip/Geezer,
Thank you. The Gryphon Antileon has only had problems in my flat. Gryphon and Absolute Sounds UK could not replicate the intermittent buzz/DC leakage problem of my amp. Is the Zanden DAC transformer leaking DC which is causing my DC-coupled amp to have problems?
I will try to fix the grounding issue separately later this week or weekend...
The Zanden potential DC leakage issue may take more time...I expect to hear back from Zanden later this week.
If there is even a chance of transformer saturation from DC on the line, isn't the easiest thing to do just block the DC before it gets to the sytem entirely?...even before it gets to my Power Conditioner? Doesn't PS Audio have some DC blockers which are otherwise passive? i think its called the humbuster, no?
Lloyd do not bother with the humbuster, highly unlikely this will help IMO.
What I would try is the 30-day trial of say both the ISOL-8 Substation LC and the latest PS Audio Power Plant 5 (the PPP has too many issues in the UK).
You need to check your amps maximum draw as both these products have a limitation, the Substation LC is 8 amps across all sockets used on it, the Power Plant 5 in the Uk I think is around 5amps continuous and 6.5amps peak.
To find those doing 30-day trials do a UK search or possibly look at the UK distributor on these manufacturer's website.
This is the quick and easy way to check I would say, and there is no purchase required, so if it works you can decide how to go forward and whether to invest in either of the products now or in the near future after chatting to your friend at the BBC.
Just checking, Mark did suggest ISOL-8, or was it IsoTek?
Cheers
Orb
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