Help me fix a hum on the Firstwatt F1/K1000

[granodemostasa]

hi.

Okay, here is the low-down, I'm borrowing the F1 from Humanflyz. I connect the F1 to my ZD as a pre and then the K1000. However, I get a hum.

where is it coming from? Well, i switch sources... that's not it. I turn the volume all the way up on the ZD and it's still the same (meaning it doesn't originate with the ZD). The only other option is that the F1 is the cause.

Since i didn't hear it at Mike's, i'm sure I must have caused it. the issue here is whether the problem is caused at the "power" source (since i'm connecting it to a general 5 outlet power strip) or the PC (since it's just a standard computer Power cord). The other option is that i may be getting interference...

[909]

where is it coming from?

headphones? (potentially, but unlikely)

I turn the volume all the way up on the ZD and it's still the same (meaning it doesn't originate with the ZD).

Not necessarily so...

The only other option is that the F1 is the cause.

I think not- he most likely would have said something before you borrowed it.

Since i didn't hear it at Mike's, i'm sure I must have caused it.

that's a possibility--didn't you have a problem with the ZD's power cord? (how did you resolve that?)

the issue here is whether the problem is caused at the "power" source (since i'm connecting it to a general 5 outlet power strip) or the PC (since it's just a standard computer Power cord). The other option is that i may be getting interference...

in my book, all logical assumptions.

You need to experiment--try differnt jacks in your place--remove the outlet power strip, etc--(I don't think it's your source or the cables). If you rule out the power, you then could eliminate the headphones by trying a few different amps. And it might be the F1, but humanflyz probably would have told you about it. I doubt you did something to it, though, you never know. It's probably the ZD. Realizze Craig didn't design it to drive or even power the K1000s. (I don't know, but it could be picking up/amplifying the hum from something and just because it doesn't get louder when you increase the volume doesn't rule out the ZD.

[granodemostasa]

i'm looking into it. part of the problem was the power apparently... i gave the F1 it's own power outlet and it got better.. but not entirely solved.

The ZD is driving the F1, not the K1000... so there isn't much stress on the ZD.

i'm looking into the possibility of tubes causing it.. so i'm switching tubes in and out...

I've never had issues with the ZD's power cord or power...but I'm not ruling that out.

I swapped ICs and it didn't do anything..

I did play the K1000 straight from the ZD for a little while.. and there was no L channel hum on that....

[909]

Didn't you loan the ZD to a friend and couldn't get the ZD to power on because of an issue with the power cord or something like that?

Anyway, do you need the ZD in the chain to power the K1000s? I bet it's the tubes. The K1000s are more sensitive 120 (ohms) than your HD650's 300 (ohms). My HD65os were obvious to certain noisy tubes that L3000 easily picked up.

[granodemostasa]

oh, i didn't finish the story. Turns out that she had only 4 of the 5 tubes in place.. and it didn't have anything to do with power... just a missing tube.

The ZD has to be the pre-amp because the F1 doesn't have a volume pot..... so yea, i'm using the pre-amp out of the ZD. My other option is to use the GS-X as the pre-amp (but i don't like that combo's sound much).

i'm going to listen and test some more to figure it out.... right now I'm suspecting my Left 6c33b...

[justin]

Did you put the ZD on top of the FirstWatt?

[humanflyz]

You scared me there for a second, because I never heard hum from my F1. So don't mess it up dude

[granodemostasa]

I have not put the ZD atop the F1 yet.. should I? right now the F1 is on the ground, like humanflyz had it at his place.

I think I'm starting to Isolate some of the issues now. there are noisy tubes in my amp. However... there is one very slight hum on the L channel that seems separated from the ZD (continues after ZD is turned off and out of the chain). i''m going to try to get people over to confirm what i'm hearing...

btw: 99% of the time, it doesn't show up... only when i'm not playing music in a quiet room and have the driver next to my ear do I ever hear anything.

also: this thing sounds incredible... this is like falling in love with music all over again...

[postjack]

I never had a hum in my system until I setup an analog rig. How I fixed that was by plugging all my audio devices (turntable, phono, amps, CDP) into one surge protector going into one outlet. Against the other wall I plugged in all my computer stuff (computer, monitor, modem, etc) into another surge protector going into another outlet.

Before I was mixing up my computer stuff and audio stuff, and this is what caused the humming. The humming is almost imperceptible now, even with no music and the volume cranked up to max.

My hum was definitely the result of a ground loop, so this probably won't help you, but I thought I'd post it anyway.

[recstar24]

Sounds like ground loop issues. Whenever you have multiple power cords plugged in different places, there is always the possibility for a ground loop, which is created when different ground potentials from the power supplies start introducing hum into the chain. If you have a keyboard around, 50 hz is around the pitch of B two octaves lower than middle C. Listen to the hum, then sing it on a tone and compare with B on the keyboard, if it matches you know you'ev got ground loop.

By plugging all your components into a single strip that ties all the grounds together, you essentially eliminate all ground potential differences between the power supplies, the difference becomes zero, hence no hum. You could also use a cheater plug that bypasses the ground pin on the cord, but do so at your own risk.

The above is only helpful if it is indeed a ground loop hum. I am pretty sure that it is not transformer hum leaking into the zana due to the external chassis. You may want to mess around with placement of the zana power supply, depending on its proximity to your source, zana main chassis or F1 magnetic fields could physically leak elsewhere along the signal chain.

[postjack]

what commander starfish said ^^^

[deepak]

Try out some IEMs out of the ZD and see if you pick up the hum in the left channel. I bought a set of tubes for my Melos off ebay (a deal too good to be true) and it turned out one of the tubes was making a very soft channel hum with the HP-2, which became much more obvious when I plugged IEMs in. It changed channels when I swapped the same tubes around to different sockets.

[deepak]

also: this thing sounds incredible... this is like falling in love with music all over again...

IMO the K1000/Pass amps really benefit from a tube pre.

[Dusty Chalk]

The other thing you need to try is to disconnect all inputs to the F1, so that all you have is amp->K1000's, no source, no pre.

[granodemostasa]

Insert Quote

The other thing you need to try is to disconnect all inputs to the F1, so that all you have is amp->K1000's, no source, no pre.

I just did this and there is no hum straight from the F1... so it must originate before it gets to the power amp.

questions: why didn't i hear anything with the K1000 straight connected to the ZD? could it be something in the connectors?... i'm going to try using adapters and the balanced inputs and see what happens then.

[cotdt]

try disconnecting earth ground

[Dusty Chalk]

That just reinforces my agreement with the opinion that it's a ground loop -- it's not any one component, it's the fact the combination, and the fact that they're connected to different earths.

Try connecting just the cables (to the F1/K1000 combination), then the pre, then the cables between the pre and the source, and so on. Work your way backwards until you have hum.

[granodemostasa]

Hi

I did your experiment.. and the problem originates when the ZD and F1 are hooked together. I've always been told that my amp should have it's own power outlet so that's what each one has.

here's how it goes:

Transport and Dac share a single filtered outlet, a triplite filter connects them

Zana Deux has it's own outlet (straight to wall)

Firstwatt has it' own outlet (straight into wall)

how should I change this configuration?

[granodemostasa]

Hey, after about a month of no hum, something happened. Is this the infamous EMI? whatever it is, a "buzz" (like a bee) is going in.... and out..... and in..................and out............. of the system on both channels.

[humanflyz]

Hey, after about a month of no hum, something happened. Is this the infamous EMI? whatever it is, a "buzz" (like a bee) is going in.... and out..... and in..................and out............. of the system on both channels.

Hmm, never heard that in my apartment before, and here I was thinking that you would take care of my gear. Just kidding.

[NotoriousBIG_PJ]

Hey, after about a month of no hum, something happened. Is this the infamous EMI? whatever it is, a "buzz" (like a bee) is going in.... and out..... and in..................and out............. of the system on both channels.

Try plugging your amp into a different outlet or into something else and see if that sound dissapears.

Biggie.