[rosconey]

after 4 different transformers in my tempest i still have a humm from the transformer-
i want to try a humm buster-
nothing else humms just the pre-
btw klaus has been great with me trying to fix the problem-

thanx

[Occam]

Ros -
http://www.audiocircle.com/index.php?topic=12706&start=0&postdays=0&postorder=asc&highlight=bridge
for a lengthy discussion and circuitry to deal with it.

and Kevin at Diycable sells a Jon Risch type that has provisions for mounting the components for a DC blocker -
http://www.diycable.com/main/product_info.php?cPath=21&products_id=536

But its quite easy to make your own with a diode bridge and 2 electolytic capacitors, see the first link.

For $299, I'd expect PS Audio's dc blocking wouldn't be the only type of hummer it should deal with....

As a shameless plug, I'll point out that the Felicia balancing power conditioner would deal with your Tempest's dc on the mains problem, quite effectively. Its EI cored transformers are not succeptable to dc and will not pass any on to your Tempest. And you'll get kick-ass power conditioning and balancing too boot, raising (IMO) its performance quite a bit.
http://www.audiocircle.com/index.php?topic=18443

[Stan Y]

Hi Occam,

I have the same issue as Rosconey (humming Tempest) and had also been following your Felicia project with a lot of interest.  (I wasn't sure that it would help with DC on the line, but I'm glad to hear it might)

I'll ask more general questions in the builders thread, but for a transformer hum problem like this one, I was wondering if any of the part values might have particular ranges that might work better.

I was particularly wondering about the value of the resistor (I may, of course,  just be confused - I'm referring to this part of the parts description:

Across the secondaries loading resistors 5-10watt power resistor, 110-100,000ohms. These are optional and not exact values, depending on the specific transformers used. They are there to preload the conditioner and reduce physical hum.

Did you mean different values would reduce hum in the Felicia unit or in units drawing power from the Felicia unit?   And, assuming I went with the transformers recommended in the builder thread, where in the range would I reduce hum the most (humming having been the bane of my listening for the last few weeks).

Thanks,

Stan

[rosconey]

thanx guys-
wayne from bolder is going to make me a buster to try-

also looked at the Felicia balancing power conditioner -dont trust myself in building it

ups killed the boxes during shipping and we thought they were causing the damage -they did damage one

[Occam]

Stan,

Felicia is not dc coupled, there is no path for entering dc on the mains line to exit from Felicia  While transformers are AC coupled (within their bandwidth) they do not pass dc. The optional resistor accross the secondaries, is there to preload and stop under some circumstances any humming of Felicia's own transformers. The current 'in process' Felicia, with its specific transformers and cap, has no resistor and doesn't hum, at all. Felicia's dual bobbin EI core transformers are far less succeptable to dc induced distorion and humming than the typical toroid.
While Felicia would certainly address any dc induced hum from a component's transformer, a simple dc blocker is more straightforward..

[Stan Y]

Rosconey - glad to hear that you've found a workable angle.  I'd been thinking about the PS Audio product as well, but they seem to have discontinued the old Humbuster and only have a $499 Humbuster + UPC-200.  Please post how well your humbuster works (if not here, on the Odyssey forum) -  I'd love to hear how it works out.

Occam - thanks for the explanation.  I've been interested in various balanced AC power products for awhile now, and, after reviewing the construction thread, although I won't say I understand exactly why it works, it certainly looks reasonable to build [way easier than even the Bottlehead Foreplay kit I did a few years back].  I've seen the DC blocker thread, but your project is just so tempting that if I can try out balanced AC and get DC blocking as a free bonus, that sounds like a lot of fun.  

I've ordered the parts through the links in the constructor thread and I'll post back either when I hit the (almost) inevitable questions, or when it's done!

[rosconey]

dam it-the hummster from wayne didnt do a thing about the hum

so guys what should i try next it must not be caused from dc

[JoshK]

I didn't know that about Felicia!  

[doug s.]

dam it-the hummster from wayne didnt do a thing about the hum

so guys what should i try next it must not be caused from dc

ya may have a ground-loop issue in yer rig; have ya tried cheater plugs yet?  if not, try 'em; if so, get klaus to send ya another tempest.

doug s.

[rosconey]

its not a ground loop-
i lifted everything- also it doesnt get louder with increased volume like a loop does-also unhooked cable and cable ground-
shut off al breakers but one and still get it,so i tried another with no luck-
will be bringing it over to a friends soon and see what it does with his power-

this is really pissing me off-
klaus probably would send another pre-but i tried one he brought back from montreal and it did it also- believe me klaus has bent over backwards trying to help-but i just might have to get another brand of pre this is so bothersome

[lonewolfny42]

You might check out this product from Blue Circle. I believe I read in the past that Jay used one in his system. Maybe send him or PhilNYC a PM to see if it would work for your problem. Good luck....

[tl1000sv]

Two words.  Balanced power.

[WerTicus]

i reallllly hate fixing hum problems

[doug s.]

its not a ground loop-
i lifted everything- also it doesnt get louder with increased volume like a loop does-also unhooked cable and cable ground-
shut off al breakers but one and still get it,so i tried another with no luck-
will be bringing it over to a friends soon and see what it does with his power-

this is really pissing me off-
klaus probably would send another pre-but i tried one he brought back from montreal and it did it also- believe me klaus has bent over backwards trying to help-but i just might have to get another brand of pre this is so bothersome

i have had ground loop issues in the past - tho they never got louder w/increased wolume.  turn up the wolume, & ya dint hear the hum.

i have also had an issue where a new preamp had a transformer hum.  a replacement preamp solved the problem.  

so, i still think you either have a ground loop hum, or klaus has gotten a bad batch of transformers, (or all these pre's have some other mfrg issue?), if a second unit did the same thing.  it will be interesting to hear the results of the pre's performance in yer friend's rig...

doug s.

[ctviggen]

Is this your house, or do you rent?  If it's your house, make sure your earth ground is really an earth ground.  You should have a ground from your breaker box to the earth, typically a metal rod pounded into the ground.  You might also have a connection to a water pipe.  Make sure these are uncorroded connections.  Make sure that anything else, like cable or phone, that is grounded has a ground coupled to the original earth ground.

[abyss]

Hi:

If I suspected power issues from the power utility or faulty facility wiring, I would try the unit at a number of different locations, such as the homes or facilities of friends and family.

If the hum persisted, then the fault would be located in the the transformer itself, possibly due to lamination problems or loose windings.
I once discovered that the steel chassis was reacting, vibrating with the transformer making it seem like the sound was coming from the transformer.  In that case I used damping rubber wedged between the chassis and transformer to stop the mechanical hum.  Or, require the seller to make good.

If I determined that my local power was at fault, I would call the power company and complain that my equipment was being interfered with by their power.  You may need to ask for the power quality department, as the person who answeres the phone number on your utiility bill will not be able to understand what you ar talking about.

Many municipalities and states set standards for power quality.  Power utility engineers may then come out and take measurements and put a power quality recording device on your breaker panel.  You may want to suggest that there is leakage to neutral or ground when you first talk to a quality engineer on the telephone.

If the power company was uncooperative, then I would consider an isolation transformer/power filter.  Often, what is called "DC" on power lines is actually a DC component that exists because of many non-linear loads in the neighborhood distorting the sine wave, so that a DC voltmeter will actually read a DC signal, even though there may be no place in the neighborhood where DC is actually injected or leaked into the power lines.

If the isolation transformer is not a good one, it may pass some of that distortion through.  So, a Topaz ultra isolator or Xentek is a good choice.  These can be found surplus, such as at Apex Electronics in Sun Valley, CA or C&H Sales in Pasadena, CA.


Note on the Felicia circuit:  There can sometimes be issues if some of your gear is plugged into balanced power, and other into conventional unbalanced power.  I theory there should be no problem, especially if the ground on the output of the balanced power transformer is connected to the bround of the input of the transformer, and thus to system ground via the breaker panel, but in practice a voltage can exist between the ground on the output of the balanced transformer and the ground in the non-balanced wall outlets in your system.  In California, possibly in all  of the USA, it is against the law for balanced power and unbalanced power to be comingled in the same system.

The benefits from using balanced power on digital gear is not usually lost if analog gear is connected to the same balanced power.  Although in practice, in two instances,  I have noticed that as I approached the load rating of the transformer, the benefit began to diminish.  Thus, supersizing the transformer seems to be a wise thing to do.


end.