[Dave Andersen]

Hello,

I recently got a DK Design VS.1 reference as a gift and paired it up with Martin Logan Motion 15 bookshelf speakers. It sounds amazing (to me anyway). However, I get an intermittent problem with the set up. Sometimes after a few minutes of being on...and sometimes hours after being on...the speakers exhibit a very high pitched whine. It's not extremely loud, but definitely loud enough to be noticed and annoy me. The only cure seems to be shutting off the stereo and turning it back on again. The noise will stay away for some time, but eventually returns. Any ideas as to what can be causing this? The noise can be heard regardless of speaker volume and is present on all inputs.

Thanks in advance!

-Dave

 

[RayDunzl]

1) Is there any other electrical item around that could be causing it? Dimmers, CFL bulbs, refrigerators, who knows?

Maybe something happens (above) that triggers the next item.

2) Amplifiers can go into self-oscillation (not a good thing).

3) You have tubes in there, are they aging? I'd guess the device could be about 10 years old.

Got access to an oscilloscope to see what's going on?

"The noise can be heard regardless of speaker volume" - The volume control adjusts the level of signal entering the amp, it doesn't turn anything up or down past that point.

Is the manufacturer still around? The old link ( www.dkdesigngroup.com ) is redirected here: http://www.thelsagroup.com/

You might give them a call.

---

Somebody else may have a better idea. Good luck.

 

[RayDunzl]

You don't have fancy speaker cables attached, do you?

Some of them can cause problems with a marginally stable amplifier (or so I've heard).

 

[Dave Andersen]

Hello Ray!

Thank you for responding to my post.

There are other electronic devices around (the amp rests above my monitor on the top of my armoir) . I initially suspected that it could be the wifi card on my computer, but the sound remains even if I power the computer/monitor off. No dimmers, CFL bulb, or fridge nearby. The tubes are likely aging. I received the amplifier used, so I'm not entirely sure if the tubes have been replaced or not over the years. The manufacturer suggests changing out the tubes to Siemens CCA tubes from the early 60's for better sound. Do you think there's a solid chance doing so could get rid of the noise?

No fancy speaker wire is attached. Just some 16 gauge stuff I got off of Amazon (had decent reviews). I even tried bypassing my subwoofer to see if that helped, but no luck there either.

Thanks again for your suggestions. I even purchased a Furman power conditioner, but it didn't help. Do you think it'd be worthwhile to get something a little higher end? I bought an entry level model.

Thanks again for your help. Would love to hear if you have anymore ideas.

-Dave

 

[RayDunzl]

That's it, just giving ideas.

Is it making the noise in both channels or only one? If both, is it the same noise?

What if you carefully disconnect and reconnect the speakers while it is whining?

Do you have any other speakers and/or cables to try?

 

[Dave Andersen]

Hah!

I think I figured it out. I noticed the sound again. Out of desperation, I shut off almost everything in the house and then realized that I had my iPhone my my desk. I usually have it nearby the computer, which incidentally, is near the amp. I took the phone out of the room and came back... High pitched whining = gone. Might be too early to jump to conclusions just yet, but the sound is gone without me rebooting the stereo (which is a first).

 

[Dave Andersen]

Spoke too soon. Damnit!

 

[RayDunzl]

If the noise is being triggered by RF...

You could liberally festoon the input and speaker cables at the amplifier with some ferrite chokes, a cheap experiment.

 

[Dave Andersen]

Interesting idea! I'll give it a shot. Thanks!

 

[Dave Andersen]

Out of curiosity

If the ferrites don't work, do you see any value in something like this:

http://www.amazon.com/dp/B000SXWGAQ...TF8&colid=2F7YZ98QMUD3Y&coliid=I210LOKTCLNJ0A

or these:

http://www.coreaudiotechnology.com/power-supplies/

I don't think I'm ready to blow anywhere near that amount of cash (MAYBE the conditioner), but was curious to see if you think it could potentially help.

Thanks

-Dave

 

[RayDunzl]

Since you have no idea what your problem is...

I wouldn't buy anything until I had a better idea what was wrong.

I suspect oscillation, could be wrong. That's pretty much an internal problem, but the load (cable/speakers) can be a contributor.

Without putting a scope on it, messing with the load (speaker/cable), or trying to narrow down what triggers it.

Maybe this, maybe that, who knows...

No one else has offered an opinion yet.

Don't know where you live, there might be a repairman lurking in your area.

---

Do you have answers to these earlier troubleshooting type questions?

Is it making the noise in both channels or only one? If both, is it the same noise?

What if you carefully disconnect and reconnect the speakers while it is whining?

Do you have any other speakers and/or cables to try?

 

[Dave Andersen]

Thanks Ray. I tried different speaker wire, but it didn't make a difference. I just attempted disconnecting/reconnecting the speakers while the noise is happening, but as soon as I reconnected them, the noise was present. I also tried swapping the speakers to different channels and still had the same issue. The whining sound seems to be more prominent to the right channel, but it's still noticeable in the left.

This thing is driving me nuts. There seems to be no pattern as to when the noise will start. Sometimes its within minutes of use, sometimes it can take an hour to kick in.

Not sure if it helps trouble shoot, but I live in a small apartment building. Maybe the neighbors are doing something that is causing the interference? It's not exactly the most well built place so I wouldn't be terribly surprised if something were wrong with the electricity here.

 

[Dave Andersen]

Called DK Design - actually got on the phone with the president of the company. I told him what was happening and he seemed pretty confident that it was tube noise. Ordered a new pair and will give it a shot.

Thanks again for your help... Very much appreciated. Will keep you posted.

 

[RayDunzl]

The maker oughta know more than me.

Careful on the inside, there might be high voltages leftover for a while after turning it off.

Wiggle those new tubes a little on insertion, to help assure a good connection.

 

[budwich]

you might consider reseating the tubes first as a "test".... making sure that contacts are good / clean.

 

[Dave Andersen]

New tubes worked

Thanks gentlemen! Turns out it was indeed the old tubes. Looks like whoever owned it last had some non-factory tubes in. The old ones are "Ei 6dj8eg"'s from Yugoslavia, which after some quick googling, appear to be pretty good? I got the stock tubes for now, but maybe will experiment with some better ones in the near future.

So happy now! Just in time for the weekend!

 

[RayDunzl]

Thanks gentlemen! Turns out it was indeed the old tubes. Looks like whoever owned it last had some non-factory tubes in. The old ones are "Ei 6dj8eg"'s from Yugoslavia, which after some quick googling, appear to be pretty good? I got the stock tubes for now, but maybe will experiment with some better ones in the near future.

So happy now! Just in time for the weekend!

Allright...

I'm glad you got it fixed and you did it yourself...