[stvnharr]

This will be a little tale of the above, and may it work for others if the occasion arises.
My Aksa's, amps and preamps were all constructed in 2003, 2 amps and a preamp.  The amps eventually became Lifeforces, and were changed in cases a time or two.  The preamp has gone thru various parts modifications and case changes as well over this same time.  In all this time, my American amp has been fairly quiet, and dead quiet with recent changes.  At the same time, my Australian amp-preamp combo has always had a bit of a hum in it.  It was very low level and untroubling.  I thought it was something to do with the tube buffer stage as all tubes do leave a small noise fingerprint.
This was all well and good until a couple weeks ago, when the hum issue entered a new dimension in the Australian system.  The hum roared up and would not go away.  I couldn't listen to music anymore.  I began dismantling everything in every box trying to find the culprit causing this calamity.  But I couldn't find anything awry. I even rewired the preamp to just an attenuator state, so a to simulate my dead quiet American system that had the same exact modified cd player, though different speakers. The hum stayed. This was deeply perplexing as everything was the same other than a few seemingly minor details that couldn’t possible amount to a hum problem. Yet, I most certainly had one.
I did google searches and learned all about ground loops in large studios and in large A/V systems. But I have a simple two box system and no ground loops.
I searched the Aspen forum for hum and star earth, and read the old threads and posts, including some by me.
But there, late on New Years Eve in the 100 degree New Years Eve heat no less, I saw a picture of someone’s amp, and there was this little wire running from the heatsink to the star earth. I wondered what this little innocuous looking wire was doing there. Nothing in anything I’d read here mentioned heatsink earthing or chassis earthing. I thought chassis earthing was to be avoided. Nonetheless, there was this little wire. I had begun to think about a chassis wire to star earth as a last resort guess of some sort as I knew the heatsink was not electrically connected to star earth but was connected to mains earth on the chassis.
Anyway, a few minutes later I had the deed done, the wire connected and I reconnected everything up ready for another runup of the attenuator listening for the hum from the speaker. And I didn’t hear the hum. I double checked to make sure I had the amp on. I put a disc on to make sure sound would come out of the speaker. I heard music. I stopped the disc and heard only silence. I turned the volume up to full blast, and still only silence. I couldn’t believe that this little wire was all it took to rid my system of 8 years of hum. It seemed too good to be true. I played a whole disc to bring in the New Year, and left everything as it was for the night, afraid to touch anything lest the silence disappear and the hum return. But the next morning the system was still silent while on and playing.
I then set about reassembling everything, including returning the preamp to actual preamp status, afterall, I had thought for 8 years that the preamp was the source of all humming, and now I would be sure to know. On came everything and I turned up the volume and all remained silent, and then I took my hand off the volume knob, and the hum returned in an unmistakable way. I retouched the knob and silence returned. It didn’t take me long to figure out that the preamp was grounding itself with ME. And it took even less time to figure out that another chassis grounding wire from board to chassis would be needed.
And all has remained silent ever since.

I didn’t mean to write such a long tale, and may all who read it find it entertaining. There haven’t been the hum threads in the past 2-3 years like there were 5-6 years ago, but the issue still comes up on occasion. And a chassis to star earth wire may not always be the solution. But if you are like me and never thought it was supposed to be there, and have just put up with a little hum from time to time, well, these amps can be DEAD SILENT.
And the GK-1 can be DEAD SILENT as well, tube buffer stage and all.

HAPPY SILENT MUSIC NEW YEAR!

[hybride]

Hi, thanks for sharing this experience. I run my LF100 on a wooden shelf. The heatsinks are not connected to earth. I don't have hum, but it's a nice tip. I had a hum in my GK1. I solved it on shorting the 10 ohm resistors between signal ground and earth.

[stvnharr]

Hi, thanks for sharing this experience. I run my LF100 on a wooden shelf. The heatsinks are not connected to earth. I don't have hum, but it's a nice tip. I had a hum in my GK1. I solved it on shorting the 10 ohm resistors between signal ground and earth.

Well, my second LF55 does not hum, and has seemingly grounded itself.  But when I return to the States I will nonetheless install grounding wires in it, same as I did here.

As for your GK-1, it is better to ground the chassis rather than short the R2's.  The resistors are there for a reason, to keep signal earth and power earth separate.  The wires only take a few minutes to install.

[stvnharr]

Well, my second LF55 does not hum, and has seemingly grounded itself.  But when I return to the States I will nonetheless install grounding wires in it, same as I did here.

As for your GK-1, it is better to ground the chassis rather than short the R2's.  The resistors are there for a reason, to keep signal earth and power earth separate.  The wires only take a few minutes to install.

I would like to add that it is a good idea to periodically resolder the power leads to the tubes. Depending on how one installs the board in a case, there can be resistricted air flow cooling of the tube socket, which will tend to dry out the solder joint where the power leads attach to the tube socket. I just had to do this, as it was a part of my problem.

Also, I have rethought the issue, and bypassing the 10R resistor between power and signal earth may be a good idea if ground hum keeps being a persistent issue. Power and signal earth are together in my cd player output stage, and all is well there.

[stvnharr]

Here is a little update to my dramas with the hum gremlins.
After seemingly having them at bay, and posting about my experience, well some unexpected things happened like the dry socket solder joints at the tubes, which didn't just dry out in the heat on New Years Eve.
Also had a bad hum return after I resoldered the tube sockets.  I did get this hum issue resolved, though not without a fair amount of the old torture and agony until I finally found something wrong.

In the end I have only made one single change to the GK-1, and that has been to run a wire to connect the grounds from each channel.  I had previously been connecting the wires at the chassis, but this now seems to add hum and hash, so I just run a single wire and solder on the big ground track of each channel.  This gives dead quiet, like the preamp isn't even on, and that's what has always been missing from this nice piece of gear.

[Grumpy_Git]

I've just silenced the hum in my GK-1 by soldering a wire between the big ground track and the power/star earth. Good or bad??

Well it's quiet.

Nick.

[stvnharr]

I've just silenced the hum in my GK-1 by soldering a wire between the big ground track and the power/star earth. Good or bad??

Well it's quiet.

Nick.

Well, I don't have a star earth as mine is just a single board EL model. But if you have silence, then it has to be good.

[Grumpy_Git]

Steven

I Thought I'd blown a fuse the first time I made the connection, true silence I'd never heard from the amp before!

Nick.

[AKSA]

Y'all,

I'm learning from this thread - thank you all, thanks particularly to Steve and Nick!

I had this notion that the power amp should have its star earth connected to chassis, and the preamp should float.

Now, I suspect BOTH pre and power should have their earths connected to chassis - I think your collective experience proves it.

Hans, do you agree with this?

Cheers,

Hugh

[stvnharr]

Y'all,

I'm learning from this thread - thank you all, thanks particularly to Steve and Nick!

I had this notion that the power amp should have its star earth connected to chassis, and the preamp should float.

Now, I suspect BOTH pre and power should have their earths connected to chassis - I think your collective experience proves it.

Hans, do you agree with this?

Cheers,

Hugh

Here is a further update on my experiences, since my initial success of a week ago vanished into the oblivion of hum shortly thereafter.
I found that the amp chassis needs to be connected to star earth thru a ground wire, but only ONE, as TWO wires will create a ground loop and hum.
The preamp ground does not need to be connected to the chassis. But the grounds from both channels do need to be connected to each other, or there will be hum.

[stvnharr]

Well, after further listening and interesting experiences I have found that I have needed to ground each channel ground to a single point on the chassis.

Since most cd players are Class II devices, double insulated and not grounded, I have found that "the ground wants to ground itself" in the next unit up the chain, in my system that is the preamp. With the floating ground of the design of the GK-1, the ground then will want to ground itself to the ground in the amp.

I found that with just the grounds of each channel connected to each other there was no ground hum as long as the cd player was not doing anything. But once the disc was being read or playing and the player was active, I would hear strange noises and sometimes some hum.
This seems to have disappeared with the chassis ground wires from each channel ground.

I think the floating ground idea would work with grounded source units.

[AKSA]

Thanks Steve,

This is very useful, helpful information.

I think, in retrospect, that my determination to keep the GK1 floating and referenced only to the power amp was not wise;  it created an ongoing problem.  So, ground the preamp to chassis, THEN the star ground to chassis on the power amp becomes optional.

Hugh

[stvnharr]

Thanks Steve,

This is very useful, helpful information.

I think, in retrospect, that my determination to keep the GK1 floating and referenced only to the power amp was not wise;  it created an ongoing problem.  So, ground the preamp to chassis, THEN the star ground to chassis on the power amp becomes optional.

Hugh

My experience is that grounding the chassis to star earth is NOT optional in order to have a dead silent amp.
My experience here in Ballarat is that I have the amp modules and power supply mounted to a subchassis which is mounted to the bottom of the case.  I also have a wire from the case bottom connected to the wire that goes to star earth, making both the case bottom and subchassis grounded together with one wire and to star earth.

[stvnharr]

I've just silenced the hum in my GK-1 by soldering a wire between the big ground track and the power/star earth. Good or bad??

Well it's quiet.

Nick.

Nick,
Since all GK-1 boards are identical, where is this power/star earth point?

[hybride]

I only earth the amplifier. I personally don't like the resistors between earth and signal ground, which is used in all Aspen equipment. It can create loops that can cause hum. I shorted them all. Much depends on the quality of the earth. I have a seperate lead to a earth pin. When i should have to use the earth in a flat it would be more carefull. IMO it's a matter of trying. 

[stvnharr]

I only earth the amplifier. I personally don't like the resistors between earth and signal ground, which is used in all Aspen equipment. It can create loops that can cause hum. I shorted them all. Much depends on the quality of the earth. I have a seperate lead to a earth pin. When i should have to use the earth in a flat it would be more carefull. IMO it's a matter of trying.

Yes, you are correct in the assessment on the resistors between earth and signal ground!
I have just finished taking out the 10R resistors in the GK-1, inserting a wire link in their stead. I no longer have hum, but dead quiet.
I have had temporary success in the past by connecting the left and right ground tracks, either directly or thru a chassis bolt, but the hum and various noises always would return.
I am fully confident now that with all the grounds together there will no longer be any ground loop hum.

[stvnharr]

Okay, here is a hopefully final post in my hum saga.
I removed the subassembly from the amp and mounted everything conventionally on the main chassis bottom.  There was no more hum once this was done. I did earth the star ground on the power supply to the chassis bottom, though it made no difference.
I have left the 10R ground to earth resistors out of the preamp since there currently is dead silence without them. I do have the preamp grounded in it's own chassis with a wire link connecting both ground channels to the earth bolt. But like in the amp, this chassis ground link made no difference. Still good to have preamp grounded in it's own chassis.

[stvnharr]

Hello,
Well this is definitely the final post in this thread. It turns out that the hum issue that plagued me was originating elsewhere in the audio system than in the amp or preamp.  This has been sorted out, and all is now well and has been so for a couple weeks now.

Nevertheless, I learned a lot in tracking the hum all down.  I read a lot of articles on grounding and ground loops, etc.  Most articles tended to be more confusing than helpful.  However there is an article on the passlabs website on grounding, that was written in 2002, that is quite good.  No link is needed, just search the passlabs, or diypasslabs websites for articles and the grounding article can be located easily.

As for the Aspen amps and preamps, I do think it a good idea to replace the 10R resistors with wire links in the grounding tracks.  I think this is mandatory in the preamp. The amp tracks are still connected by the diodes, which while not ideal still do the job well.

The bottom line is that there should be NO HUM of any kind in an Aspen amp or preamp!  And it can easily be achieved.

[AKSA]

Thanks Steve, Hans,

I will chew this over carefully.  It appears I can learn something here, and I'm most grateful,

Cheers,

Hugh

[Jens]

This is very interesting. Initially, I had huge hum problems with my GK-1R, but these are now more or less solved, involving various measures like shielding all signal wires within the enclosure etc. etc. Also, I used to have my whole system grounded to true ground (through earth connection on power plug), which helped a lot. However, I never got it completely silent (but then that is difficult with 94-96 dB efficiency speakers).

I haven't got the grounding in place yet in my new home, but all wiring has been done and I just need to fit the wall outlet.

However, I am wondering if I may benefit from shorting the R2s (I believe those were the ones) on the GK-1 main board as well.

Also, I am wondering if the NAKSA 70 and NAKSA 100 "suffer" from the same philosophy as previous products, and - in the affirmative - if anything could be done to remedy the grounding scheme on these amps as well, if indeed it needs any remedying at all 

Master Hugh, what say ye, Sire?

Cheers,

Jens