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K3 Speaker cabinet resonances

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Deni F5VJC

K3 Speaker cabinet resonances

Has anyone found a solution to the cabinet buzz from the K3 internal speaker?

I've not used the internal speaker until recently on my K3 and now find I have annoying cabinet buzz around 450Hz and 600Hz, not so good for CW!

I haven't tried any damping as yet and just wondered if anyone has managed to cure this cabinet resonance.

73,Deni
F5VJC
K3 325

Steef PA2A

Re: K3 Speaker cabinet resonances

Deni,

I have used two nuts on each mounting screw. The first nut is very loose,
and the second nut is tight against the other one. The screws can be rotated
by hand. Two nuts are needed to prevent them from falling into the rig.

73 's Steef PA2A
K2 4654
K3 1184

----- Original Message -----
From: "Deni F5VJC" <[hidden email]>
To: <[hidden email]>
Sent: Wednesday, October 08, 2008 10:59 AM
Subject: [Elecraft] K3 Speaker cabinet resonances

>
> Has anyone found a solution to the cabinet buzz from the K3 internal
> speaker?
>
> I've not used the internal speaker until recently on my K3 and now find I
> have annoying cabinet buzz around 450Hz and 600Hz, not so good for CW!
>
> I haven't tried any damping as yet and just wondered if anyone has managed
> to cure this cabinet resonance.
>
> 73,Deni
> F5VJC
> K3 325
>
> --
> View this message in context:
> http://n2.nabble.com/K3-Speaker-cabinet-resonances-tp1306081p1306081.html
> Sent from the Elecraft mailing list archive at Nabble.com.
>
> _______________________________________________
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> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
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GM0ELP

Re: K3 Speaker cabinet resonances

In reply to this post by Deni F5VJC

Hi Deni,
I found that placing some tape round the chassis metal work that comes in contact with the top panel completely cured the problem. Certain notes were causing the top panel to vibrate against the top of chassis (no matter how tight the screws were) and having the tape between them dampened the effect.

Doug

Nick Kennedy

Re: K3 Speaker cabinet resonances

In reply to this post by Deni F5VJC

I tried various things recommend here on the list and I think cabinet
buzz is no longer an issue. But I still have a bad resonance or other
effect in my built-in speaker itself. In decreasing frequency, it
starts buzzing at around 340 Hz, worse at 330 Hz, slight at 320 Hz, and
then gone. I pretty much can't use the built-in speaker. At moderate
volume levels, even band noise excites those resonances and makes a kind
of pulsing, buzzing noise like rough CW.

For additional info - I'm not a musical "golden ear", I don't expect
high fidelity out of the built-in speaker, and I'm pretty crazy about
the K3 overall. Yes, I know I should contact support, but I want to get
my facts together and maybe even make some recordings first.

73--Nick, WA5BDU

Deni F5VJC wrote:

> Has anyone found a solution to the cabinet buzz from the K3 internal speaker?
>
> I've not used the internal speaker until recently on my K3 and now find I
> have annoying cabinet buzz around 450Hz and 600Hz, not so good for CW!
>
> I haven't tried any damping as yet and just wondered if anyone has managed
> to cure this cabinet resonance.
>
> 73,Deni
> F5VJC
> K3 325
>
>

dmb@lightstream.net

Re: K3 Speaker cabinet resonances

Hello Nick,

Sometimes, due to either a manufacturing defect or mechanical shock, the
magnet that surrounds the speaker voice coil will get shifted slightly.
When that happens, the voice coil may come into contact with the magnet
and it can sound pretty bad. Not sure that's what's happening in your
case, but I'd suggest trying a replacement speaker.

I don't have a K3 so the following recommendation may not be relevant,
but I'd also suggest that if you replace the speaker, make a thin felt
gasket that you can place between the speakers frame and the cabinet.
You can probably go to the local fabric store and ask if they have a
small scrap that you can have. Using the gasket should reduce the
likelihood of vibration between the speaker frame and the cabinet.

Haven't followed this entire thread, so apologies if this is a re-hash
of a prior suggestion.

73, Dale
WA8SRA

Nick-WA5BDU wrote:

> I tried various things recommend here on the list and I think cabinet
> buzz is no longer an issue. But I still have a bad resonance or other
> effect in my built-in speaker itself. In decreasing frequency, it
> starts buzzing at around 340 Hz, worse at 330 Hz, slight at 320 Hz,
> and then gone. I pretty much can't use the built-in speaker. At
> moderate volume levels, even band noise excites those resonances and
> makes a kind of pulsing, buzzing noise like rough CW.
>
> For additional info - I'm not a musical "golden ear", I don't expect
> high fidelity out of the built-in speaker, and I'm pretty crazy about
> the K3 overall. Yes, I know I should contact support, but I want to
> get my facts together and maybe even make some recordings first.
>
> 73--Nick, WA5BDU
>
>
> Deni F5VJC wrote:
>> Has anyone found a solution to the cabinet buzz from the K3 internal
>> speaker?
>>
>> I've not used the internal speaker until recently on my K3 and now
>> find I
>> have annoying cabinet buzz around 450Hz and 600Hz, not so good for CW!
>>
>> I haven't tried any damping as yet and just wondered if anyone has
>> managed
>> to cure this cabinet resonance.
>>
>> 73,Deni
>> F5VJC
>> K3 325
>>
>>
>
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>

Deni F5VJC

Re: K3 Speaker cabinet resonances

In reply to this post by Deni F5VJC

Thanks to all who responded to this question.

Having looked into it further it seems I have a combination of cabinet buzz and a defective speaker.
I removed the top panel of my K3 did tests and found the most bothersome buzz at 600/610 Hz is still present with the top panel detached.
Checked screws all tight (not too tight) and various other mechanical tweaks but can't clear it. So I guess I will email Elecraft support about a possible replacement speaker.

This is a very small annoyance in an otherwise fine radio, and it's just come to light now because I always used external speakers or headphones until now, having reduced my K3 to bare bones due to an impending move of shack, I'm listening to it's internal speaker.

73, Deni
F5VJC
K3 325

Deni F5VJC wrote

Has anyone found a solution to the cabinet buzz from the K3 internal speaker?

I've not used the internal speaker until recently on my K3 and now find I have annoying cabinet buzz around 450Hz and 600Hz, not so good for CW!

I haven't tried any damping as yet and just wondered if anyone has managed to cure this cabinet resonance.

73,Deni
F5VJC
K3 325

Jim AB3CV

Re: K3 Speaker cabinet resonances

In reply to this post by dmb@lightstream.net

i too found my speaker buzzy. i fiddled a bit and discovered that the grill cloth had bagged just a bit when i put everything together and was just barely touching the speaker cone edges under certain output conditions.

i removed and trimmed it more carefully then made sure it was taut when reassembled. seems ok now.

jim ab3cv

Phil Salas

K3 Speaker cabinet resonances

In reply to this post by Deni F5VJC

"I tried various things recommend here on the list and I think cabinet
buzz is no longer an issue. But I still have a bad resonance or other
effect in my built-in speaker itself. In decreasing frequency, it
starts buzzing at around 340 Hz, worse at 330 Hz, slight at 320 Hz, and
then gone. I pretty much can't use the built-in speaker. At moderate
volume levels, even band noise excites those resonances and makes a kind
of pulsing, buzzing noise like rough CW."

Nick - This sounds the way my speaker sounded. Turns out it was a bad
speaker. The way to check this is to remove the speaker from the cabinet
and just hold it while it is plugged in. If it is still distorting, get
Elecraft support to send you another speaker.

Phil - AD5X

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Joe Planisky

Re: K3 Speaker cabinet resonances

In reply to this post by Deni F5VJC

Hi Deni,

I had a bit of resonance at 300 & 310 Hz. There is a screw just below
the speaker grille that holds the chassis stiffener bar to the top
cover. I found that leaving this screw just a tiny bit loose (or
perhaps, not tightening it completely would be a better way of saying
it) completely eliminates all cabinet buzz on my K3.

73
--
Joe KB8AP

On Oct 8, 2008, at 1:59 AM, Deni F5VJC wrote:

>
> Has anyone found a solution to the cabinet buzz from the K3 internal
> speaker?
>
> I've not used the internal speaker until recently on my K3 and now
> find I
> have annoying cabinet buzz around 450Hz and 600Hz, not so good for CW!
>
> I haven't tried any damping as yet and just wondered if anyone has
> managed
> to cure this cabinet resonance.
>
> 73,Deni
> F5VJC
> K3 325
>
> --
> View this message in context: http://n2.nabble.com/K3-Speaker-cabinet-resonances-tp1306081p1306081.html
> Sent from the Elecraft mailing list archive at Nabble.com.
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com

Nick Kennedy

Re: K3 Speaker cabinet resonances

In reply to this post by Nick Kennedy

Thanks to folks who gave specific suggestions again. In my first
session, I'd put weather stripping and double stick tape under the cover
and on the shield behind the front panel. But I still had a highly
irritating buzz in the 330 to 360 Hz range when on the internal speaker.

OK, so I took the top cover off again and cranked the sidetone level up
to 47, then ran it through the suspect pitch range. The speaker didn't
sound too bad if I damped it by holding the magnetic shield, but it was
pretty much OK even if I did not do that. So it's something inside the
cabinet doing a sing-along. How can I apply excitation to suspect parts
and see what's doing it? By leaning the top plate against the cabinet
with the magnetic shield touching the top edge, I was able to couple
enough audio into the box to make it happen. Turns out one or more of
the crystal filters are singing. I have all slots filled and at 350 Hz,
the one on the far right is doing Karaoke to the sidetone. When I go to
340 Hz, one or more of the others join in.

I'm not sure how to make it/them shut up at this point. It takes
significant finger pressure to quiet them down, so a bit of foam strip
may not do it. I haven't gone to the bottom to check or tighten the
screws yet. I'm going to stew on that a while first. Probably need to
remove a filter completely and examine it to come up with a plan. I'm
also reluctant to stick things to the tops as I might mess up the labels.

73--Nick, WA5BDU

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