Hum problem with GK-1R - solved!

Jens · « **on:** 8 Apr 2004, 08:41 pm »

Friends, countrymen and fellow AKSAphiles!

After almost a month of endless testing, soldering and loads of emails back and forth to Hugh, I finally managed to nail the hum 'ghost' in my GK-1R to the ground (literally) this morning.

It turned out that the problem had nothing whatsoever to do with the layout (which neither Hugh nor I thought it had, although we came to have our doubts as time went by and nothing we could come up with seemed to help) or the the wiring.

Nor was it to do with faulty components or the design of the GK-1R - or even an error that I had made in the assembly process.

Instead it turned out to be a combination of things (this is the way I see it), such as the slightly unorthodox earthing scheme of my whole system, combined with the 'collaboration' between the Analogue and the Relay pcbs of the GK-1R, my interconnects, and perhaps a few other things that I don't know about.

The hum problem was solved by running a wire from one of the output ground pins on the Analogue PCB to the output ground plane on the Relay PCB. For now, the 'output ground plane' equals the metal housing of one of the RCA plugs on the interconnects running to the power amps (this was the easiest place to put a croc clip

)

Obviously, I will try to implement this 'grounding link' in a more elegant manner. I will let you know how, but now I'll just sit back and listen to the lovely music that comes out of my system

Thanks to everyone who sent me emails with good (and sound) suggestions - and a special thanks to Hugh for his inordinate patience in answering a huge load of emails!

Happy Easter to all!

Cheers,

fred · « **Reply #1 on:** 9 Apr 2004, 01:56 am »

Congratulations!

Having gone through similar pains with solving my hum problem, I can certainly relate to what you went through. As I had mentioned in an email to you, my problem required multiple solutions - because of my unfortunate configuration. In both our cases, perseverence paid off.

Now you can sit back and simply enjoy!

Martin · « **Reply #2 on:** 9 Apr 2004, 05:20 am »

Congrats Jens
I remember the feeling I got when I realized that my hum was all of a sudden, just not there...think I got tears in my eyes.
Feels pretty good...sounds even better!
Martin

dayneger · « **Reply #3 on:** 12 Apr 2004, 02:57 pm »

Hi Jens,

I have two words to say to you:

THANK YOU!!!

I'd already fired off a sob letter to Hugh describing all of my hums and buzzes when I happened to see your post here. After checking with two alligator clips to prove the concept, I ran wires from the output signal ground on the preamp board to the signal ground on the relay board, et voila!! Silence.

Channels without any source are still noisy, but when it comes down to it, who cares?

Now that everything's finally working it's time to

.

Oh, the implementation was cake. I just drilled a 1.5mm hole through the ground pin track on the relay board, scraped away a bit of the green stuff, and soldered the two wires on. It actually was silent with just one channel connected, but I went for the symmetry thing.

So, all of your pain and agony has already helped another AKSAphile out!

Thanks again and cheers,

Dayne

PSP · « **Reply #4 on:** 12 Apr 2004, 06:03 pm »

Hi Dayne.
If you hear noise on unused inputs, I would suggest shorting those inputs (use the cheapest possible male RCA loaded with something between zero--a jumper wire--and 5kOhms--recommended for some reason by VoltSecond in the Foreplay) to see if you can further reduce the noise floor.

For the newbies who read this someday, we want to short unused inputs; do not short any of the outputs. Unused digital coax outputs on a CDP can be terminated with a 75R load, of course.

My GK1-R is still several weeks away from completion.

Have fun,
Peter

dayneger · « **Reply #5 on:** 12 Apr 2004, 08:03 pm »

Hi Peter,

Thanks for the tip! Hugh included some terminater plugs with the kit, but I couldn't see well enough inside. Do these short the input as you're suggesting?

Good luck as well with your GK-1R! Mine reached "operational" today, which doesn't yet correspond to "completion". . . this is always the worst phase for me, since once music's flowing I find it hard to buckle down and finish everything off properly!

Cheers,

Dayne

Jens · « **Reply #6 on:** 12 Apr 2004, 09:13 pm »

Hi Dayne,

I'm so pleased that all my blood, sweat and tears could help you out, too! I should mention again that I wouldn't have been where I am today with this issue had it not been for the magnificent assistance from Hugh. I have too admit that I've put him through a heavy email bombardement, and he always answered quickly and in good humour. Thanks again, Hugh!

So far, I have only wired the ground connection to one channel, but I am going to do both, just like you - for the sake of balance. Actually, there are two small holes in the Relay PCB to the left of the mute relay (RLY6). These are in direct contact with the ground plane, so I am using these, simply soldering a CAT5E wire directly onto the pcb.

Now - you too can sit back and enjoy!

Cheers,

Jens

AKSA · « **Reply #7 on:** 13 Apr 2004, 03:53 am »

Folks,

I've spoken at length with Fred, Jens and Dayne and it seems I made a boo-boo with the earthing regime on the GK1-R.

It's fixed now forever. My sincere apologies for the inconvenience.

The solution is simple. We replace LINK1 on the Relay board (also called the input/output pcb) with a 0R resistor, or even a simple wire link.

That fixes it completely....... no more hum, no more tangles.......

I've updated all subsequent documentation.

Many thanks to all for the patience!

Cheers,

Hugh

Jens · « **Reply #8 on:** 13 Apr 2004, 05:42 am »

Quote from: AKSA

Folks,

I've spoken at length with Fred, Jens and Dayne and it seems I made a boo-boo with the earthing regime on the GK1-R. It's fixed now forever. My sincere apologies for the inconvenience.

The solution is simple. We replace LINK1 on the Relay board (also called the input/output pcb) with a 0R resistor, or even a simple wire link.

That fixes it completely....... no more hum, no more tangles.......

I've updated all subsequent documentation.

Many thanks to all for the patience!

Cheers,

Hugh

Hi Hugh,

Just a small note: I already tried this earlier in my system, and although it solved part of the problem, there was still hum in some situations.

The solution that Dayne and I are using may still be necessary for some people - depending on their system setup. However, it is extremely easy to implement, so it's not a problem.

Cheers,

EchiDna · « **Reply #9 on:** 18 Apr 2004, 07:44 am »

Quote from: AKSA

Folks,

I've spoken at length with Fred, Jens and Dayne and it seems I made a boo-boo with the earthing regime on the GK1-R. It's fixed now forever. My sincere apologies for the inconvenience.

The solution is simple. We replace LINK1 on the Relay board (also called the input/output pcb) with a 0R resistor, or even a simple wire link.

That fixes it completely....... no more hum, no more tangles.......

I've updated all subsequent documentation.

Many thanks to all for the patience!

Cheers,

Hugh

does this mean that the version I have (construction notes are version 1.2) is now out of date and been superceded Hugh?
ie, should I replace the 10R resistor with plain wire? my relay board is still not up and running, which is pretty slow considering I got it as a Christmas pressent from the missus!

AKSA · « **Reply #10 on:** 18 Apr 2004, 08:16 am »

Yes, Glen,

You have it in one. Follow these posts; replace LINK1 on the relay pcb with two wires; both from the earth on the output side, one to left channel earth on the analog pcb, and one to the right channel earth on the analog pcb.

I will make up a short addendum to mail out to people. That will avoid much gnashing of teeth.........

Cheers,

Hugh

EchiDna · « **Reply #11 on:** 18 Apr 2004, 08:32 am »

er...

hmm, ok so I desolder Link1, then solder 1 wire to each if the two holes, then connect each wire to it's respective channel's earth on the analogue board?

I think that is it... right?

ps - I updated the gallery post as I had some time to kill

AKSA · « **Reply #12 on:** 18 Apr 2004, 10:09 am »

Hi Glen,

Close, except that the wires both must originate on the right hand side of LINK1; you might need to drill another hole just to the right of the RHS LINK1 hole.

Then one wire to left channel analog board, and the other to right channel analog board.

No other changes. That's it.

Cheers,

Hugh

Jens · « **Reply #13 on:** 18 Apr 2004, 10:23 am »

Hi Glen and Hugh,

As described previously, you can actually use the two small holes between the RIAA circuit and the Mute relay, thus avoiding any drilling. I don't know whether this would be in the way for anyone having the RIAA. Hugh?

Also, I have not removed the LINK1 resistor, since it is bypassed anyway. No adverse effects so far. Does it matter?

Cheers,

dayneger · « **Reply #14 on:** 19 Apr 2004, 06:09 am »

I also left the Link1 10R resistor mounted, so far with no adverse effects.

I tightly twisted the CAT5E tube output wire with a second run of wire to the nearby ground pin, which seemed better than having just the single run of output wire anyway.

On the relay board you can put a new hole through the output signal track, which worked better for me since my pretwisted wires were just barely long enough to reach the middle there

, or use the existing holes that Jens mentioned.

Just wanted to confirm again that this configuration hasn't hummed or buzzed a wink since I installed it! Thanks again, Jens.

Cheers,

Dayne

AKSA · « **Reply #15 on:** 19 Apr 2004, 08:16 am »

Jens,

There is absolutely no problem with using the two wire stirrup holes on the relay pcb for your two wires to the analog left and analog right ground.
It won't interfere at all with the phono operation.

Dayne,

I'm delighted this fix has worked for you. I'm not sure how it came around; I forget the details in all Jens and my correspondence, but I suspect I suggested changing out 10R for a link, 0R resistor. In any event, Jens suggested the full on, belts-and-braces approach of two dedicated earth wires back to the analog pcb, and this proved even more successful.

Cheers,

Hugh

Jens · « **Reply #16 on:** 19 Apr 2004, 09:14 am »

Quote from: AKSA

Jens,

There is absolutely no problem with using the two wire stirrup holes on the relay pcb for your two wires to the analog left and analog right ground.
It won't interfere at all with the phono operation.

Dayne,

I'm delighted this fix has worked for you. I'm not sure how it came around; I forget the details in all Jens and my correspondence, but I suspect I suggested changing out 10R for a link, 0R resistor. In any event, Jens suggested the full on, belts-and-braces approach of two dedicated ...

Hi Hugh,

Good - no reason not to use holes that are already there.

How about the 10R LINK1 resistor - do you reckon it should be removed, or doesn't it matter one bit?

And yes, you are right, you did suggest changing the LINK1 resistor for a wire, which did not really do the trick. However, it did prompt me to try the solution we have come up with now. Quite a synergistic approach, eh?

Cheers,

AKSA · « **Reply #17 on:** 19 Apr 2004, 12:17 pm »

Hi Jens,

Thanks for your post.

Nah, you can leave it in; at 0R along the wires and 10R through the link it's pretty clear where the return earth signal will pass; it won't make any difference!

Cheers,

Hugh

Jens · « **Reply #18 on:** 19 Apr 2004, 02:56 pm »

Hi Hugh,

Thanks for the info. Didn't think it would matter (which is why I just left it in the first place).

I have to say that I am pleased that our combined efforts resulted in such a simple solution to a small, but annoying problem!

Also, I am very pleased that it has proved helpful to others than just myself.

I should add, though, that without your steadfast assistance I might still be mucking around with it instead of listening to lovely music!

Cheers,

econ · « **Reply #19 on:** 24 Jun 2005, 09:58 pm »

Jens would it be possible to post a sketch of your changes ? Ive seen Ron R's sketch .Its difficult to visualise whats being described sometimes and some of us have boards that are schematically identical but the layout on the pcb is different.

Is there a difference in hum between GK1 R and GK1 M ? I could forego the remote bit ,if the GK1M is quieter.

Am at the point of assembling the GK1R in the case for final testing

Thanks guys.