Tim,
> you don't have as complete a picture as some of us who have actually
> tested this.
I *HAVE* used amplified (powered) speakers with the K3 and I've used
bookshelf speakers and I've used cheap cellphone "hands free" kit
speakers with the K3. I also have almost 40 years experience in
professional audio - from recording studios to radio stations to TV
stations and designing broadcast facilities - I'm more than capable
of critical audio analysis.
The point is that the K3 does not need another 3W per channel external
audio amplifier - that simply duplicates the internal amplifier - if it
is coupled with reasonably efficient, external, front facing speakers.
Even a pair of the MFJ or Jetstream "communications" speakers are
*half* the cost of the COMspkr - they're passive with no chance of
RFI and they work just as well with the K3's internal amplifier as the
COMspkr or other 3W per channel powered "computer" speakers.
*IF* one feels the need for an external amplifier, bypass the internal
amplifier by using the Line Out and high cut filter to drive a better
amplifier - something capable of 10W per channel at 0.01% THD instead
of 3W per channel at 1% THD like the COMSpkr. Alternatively, set up
the external amplifier with a 16 - 32 Ohm input impedance, set the K3
to low AF gain to keep the LM4950 in the cleanest part of its design
range and use the external amplifier to provide the power gain.
Just like RF power amplifiers, audio amplifiers are all about selecting
the right devices, using proper design and bypassing, then matching to
the right load. An audio amplifier needs to be able to source enough
current to drive the speaker without saturation or clipping. The audio
chip used in COMspkr and other 3W per channel computer speakers is
simply no better or cleaner than the LM4950 used in the K3 - they all
show high THD when operated at maximum output level because they just
can not source the current without driving the outputs into saturation.
That is nothing more or less than simple physics.
> The COMspkr is so damn loud that it practically blasts me out of my
> den if I turn it up much.
I can hear the K3 at the opposite end of the house with the internal
amplifier and my bookshelf speakers. Again, one does not need just
another set of 3W per channel computer speakers. If one wants cleaner
audio, use a bigger, cleaner external amplifier for the power gain
but with decent, efficient speakers, the 3W/channel amplifier in the
K3 is more than sufficient and certainly just as good as 3W/channel
computer speakers.
73,
... Joe, W4TV
On 11/7/2012 12:11 AM, Tim Tucker wrote:
> Sorry Joe, but I'm with Fred on this one, as well. You're speaking from
> what you believe to be true based on specs you're reading, but it's obvious
> to me as one who has actually used various speakers on the K3, including
> the COMSpkr, that you don't have as complete a picture as some of us who
> have actually tested this.
>
> I love the K3 and wouldn't trade it for another rig, but it's not perfect.
> It's ability to drive external speakers is one of the examples where it
> does not excel. Compared to other rigs, it basically sucks . Period. I'm
> young compared to most of you guys and have no hearing loss and have quite
> a good reputation amongst my friends for having an ear for what *sounds*
> good. After trying quite a few different external speakers setups with the
> K3 and not being happy with the overall volume output, I decided that the
> K3 was probably too finicky with what it needs for speaker impedance and
> decided to just go with a set of powered external speakers and be done with
> it. The COMspkr is so damn loud that it practically blasts me out of my
> den if I turn it up much. I don't like to use headphones if I don't have
> to, and with the COMspkr, I rarely need to.
>
> Regardless of what you think the specs say, you need to try this for
> yourself and make an informed decision.
>
>
> On Tue, Nov 6, 2012 at 5:39 PM, Joe Subich, W4TV <li...@subich.com> wrote:
>
>>
>> > The COMspkr is an ampflied speaker.
>>
>> That's right and the amplifier is not any stronger than the amplifier in
>> the K3. There is no value to using a set of 3W per channel amplified
>> speakers on a transceiver that provides 2.5W per channel by itself.
>>
>> I've used a pair of $5 speakers from surplus cellphone "remote kits" on
>> the K3 that sound as good as any amplified computer speakers (and I've
>> used a lot over the years). If one is going to use amplified speakers
>> use speakers capable of significantly more *clean* power than what is
>> essentially a low end commodity product.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 11/6/2012 6:34 PM, Fred Smith wrote:
>>> Joe
>>>
>>> The COMspkr is an ampflied speaker. Hell I have a set of Bose speakers
>> here
>>> that were close to $500 and don't sound any better on a radio than the
>> $39
>>> ones and they are as loud as you want. I got to call you on this one just
>>> from using as many sets of speakers as I have.
>>>
>>> Fred/N0AZZ
>>>
>>> -----Original Message-----
>>> From: elecraft-boun...@mailman.qth.net
>>> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Joe Subich, W4TV
>>> Sent: Tuesday, November 06, 2012 4:43 PM
>>> To: elecraft@mailman.qth.net
>>> Subject: Re: [Elecraft] K3 Speaker buzz - But which external speaker ?
>>>
>>>
>>> The COMSpkr is rated at 3W per channel ... barely better than the 2.5W
>> per
>>> channel of the K3. A good pair of bookshelf speakers will provide
>>> everything that the COMspkr does with arguably better sound than the
>> small
>>> speakers in the COMspkr enclosures.
>>>
>>> A good technician can probably make a $10 pair of computer speakers as
>> "RF
>>> proof" as the COMspkrs just by installing the RC RFI suppression networks
>>> most manufacturers leave off the standard amplifier board!
>>>
>>> 73,
>>>
>>> ... Joe, W4TV
>>>
>>>
>>> On 11/6/2012 5:00 PM, Fred Smith wrote:
>>>> IMHO the best bang for the buck are the West Mountain Radio COMspkr
>>>> for $39 they have no equal. I have speakers in the shack that cost up to
>>> $400 ea.
>>>> and these sound the best on my K3's and Never any RF on them with
>>>> legal limit ++.
>>>>
>>>> 73,
>>>> Fred/N0AZZ
>>>>
>>>> -----Original Message-----
>>>> From: elecraft-boun...@mailman.qth.net
>>>> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of drewko
>>>> Sent: Tuesday, November 06, 2012 3:10 PM
>>>> To: Elecraft@mailman.qth.net
>>>> Subject: Re: [Elecraft] K3 Speaker buzz - But which external speaker ?
>>>>
>>>> I am using a pair of MFJ-281 Cleartone speakers with my K3.
>>>>
>>>> Some say they are fantastic; some say they are junk... But they work
>>>> well enough for me for CW and SWL. They peak around 600-700 Hz. I
>>>> would prefer a little lower, 400-500 Hz, but they work ok in that
>>>> range. And no buzzing anywhere that I have heard. They also look like
>>>> they were made to match the K3.
>>>>
>>>> As for RF, I have had no issues with them. The lead-in of my end fed
>>>> wire antenna is inches away from them (though I do only operate 10 watts
>>> output).
>>>>
>>>> 73,
>>>> Drew
>>>> AF2Z
>>>>
>>>>
>>>> On Tue, 06 Nov 2012 20:18:45 +0000, Iain G4SGX. wrote:
>>>>
>>>>> Hello,
>>>>> Well after 18 months the buzzing of the K3 internal speaker has
>>>>> reached annoying proportions.
>>>>> For a while it faded after switching on for 10 mins but now its a
>>>>> constant resonance at 580 Hz. Great for CW! (not) Because of the
>>>>> above I am sure its because the coil has shifted in the speaker
>>>>> slightly rather than any sympathetic resonances from the case.
>>>>>
>>>>> I'm not complaining, I understand if I contacted Elecraft I am likely
>>>>> to get a replacement speaker sent out, (Its a well documented 'extra
>>>>> feature') but really haven't got round to it, nor am i likely too,
>>>>> well down the list of priorities!
>>>>> Will probably order it along with a set of CW filters when I need them.
>>>>>
>>>>> I'm REALLY after recommendations for an external shack speaker, or is
>>>>> any good HiFi speaker good enough? I would assume some RF shielding
>>>>> and good high end sensitivity was more of an issue.
>>>>>
>>>>> Yours.
>>>>> Iain G4SGX.
>>>>> Happy K3 Owner :)
>>>>> ______________________________________________________________
>>>>
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