[Elecraft] My K3's hissy and noisy audio

[Maarten van Rossum]

Hello everybody,

During last CQ WPX contest I got the chance to put my K3 to work at our
contest station PI4DX. We participated in the Multi One klass which allows
us to use 2 radio's, one running station and one multiplier station.
We used my K3 on the running station and a Icom IC-7700 on the multiplier
station. This was actually the first time I could compare the K3 to a high
end transceiver such as the IC-7700. I was surprised to find out that the
7700 sounded much better. The receiver was less noisy an easier to listen
to. Several other operators also stated the K3's audio was hissy and sharp
and not nice and smooth.
We could hear it using the built-in speaker as well as on a Heil Pro Set
Plus.
The RX EQ is flat and I used the 2.7 filter on a 2.7 KHz bandwidth.
Narrowing the bandwidth makes it worse but that is to be expected. No NB or
NR was used. AFX on or off makes no difference. In addition to the 2.7 KHz
filter my K3 also has the 2.1, 1.8 KHz and the 400 Hz filters. It doesn't
have the 2nd receiver, the KXV3, KBPF3, or the KTCXO3. It does have the
KDVR3, KAT3 and the KPA3. (will order a KXV3 module shortly)

After reading all these glowing reports on the K3's smooth receiver I can
only draw one conclusion; there must be something wrong with my K3.

What could it be?

73, Maarten van Rossum
PD2R
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elec...@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

[Jim]

Maarten, I found just the opposite having compared my K3 with two separate
7700's with the K3 winning out each time.

Also my wife being a non Ham picked the K3 audio over both of the 7700's
each time.

73 de KE4WY Jim

[Enno, PF5X]

Hi Maarten,

I tend to agree with your observations. If you live in a noisy environment like I do, the K3 RX can be quite "restless" and listening fatigue comes in easy. I played with the AGC setting a while ago and came up with the following settings in the CONFIG menu: AGC SLP 008, AGC THR 006. This gives the RX a more analogue behaviour and it increases the distance between the background noise level and desired signal. I am still using F/W 2.76, so the new options in F/W 3.0x might be able to further improve the situation.

-- Enno, PF5X
K3 #1263

Hello everybody,

What could it be?

--
View this message in context: http://n2.nabble.com/My-K3%27s-hissy-and-noisy-audio-tp2588008p2588162.html
Sent from the Elecraft mailing list archive at Nabble.com.

[Maarten van Rossum]

Thanks everybody for your replies,

I have played with the shift and Hi/Low cut and although it does help, it's
not what is should be.
The radio was not used in a noisy environment, it is usually fairly quiet
here. I will however have a look into the AGC settings and see if that
brings any help.

I still think there is more to this but I cannot really put my finger on it.
The difference between both radio's was pretty big.

73, Maarten

[Paul Christensen]

> We used my K3 on the running station and a Icom IC-7700 on the multiplier
> station. This was actually the first time I could compare the K3 to a high
> end transceiver such as the IC-7700. I was surprised to find out that the
> 7700 sounded much better.

Maarten,

At my station, the K3, '7700, and '7800 are side-by-side. Of all three
transceivers, the K3 produces the least amount of residual hiss. In fact.
when the AF control is turned full CCW on the Icom's, a slight degree of
hiss remains. Zero hiss with the K3. If you look at the audio structure of
the K3's headphone circuit, it would be pretty difficult to improve upon
when using a single-ended power supply. When bi-polar power supplies are
used, it's possible to eliminate intra-stage coupling capacitors with
servo-controlled op-amps, thereby eliminating DC offsets. Larger voltage
swings are possible with bi-polar supplies and overall distortions are
generally lower with these circuits. You tend to find these techniques used
in Hi-Fi audio and broadcast equipment, but not in communications-grade
audio systems.

One important point is that the stock K3 has less low-end audio response
than that of the two Icoms. But that's a personal choice. Some
well-respected ops here detest the presence of low-end audio below ~ 200 Hz.
Others (myself included), like to hear the entire passband while
operating -- right down to 50 Hz or so. It's not right, it's not wrong -
it's just a personal preference one way or the other. My personal choice
is to open up the audio response, then limit low-end and high-end response
through the K3's DSP filtering. I get the best of both worlds that way...

In order to attain a richer low-end response on the K3, you may wish to
review my mods on the N1EU website. After modification, the K3 is capable
of sounding just as rich and smooth as the two Icoms. My guess is that when
you use the adjective "sharp," you're likely hearing a lack of low-end
balance as both transceivers are capable of extremely sharp low-pass
response.

If you do invoke the mods, I would suggest first looking at the revision of
your Main DSP Board as some of components I've changed may have now gone
into production at Elecraft. It may also turn out that Elecraft eventually
scales the audio R values rather than C values to accomplish the same end
result. I changed C values since fewer components are changed that way.

Paul, W9AC

[Evert Bakker (PA2KW)]

Maarten Wrote:

" Several other operators also stated the K3's audio was hissy and sharp
and not nice and smooth. We could hear it using the built-in speaker as well
as on a Heil Pro Set Plus."

I think there is nothing wrong with your K3.

About a week ago I reported the "bad" audio quality of the K3 but especially
*in combination* with the (latest version of) Heil Proset headset. I guess
that the wider freq-response of this headset is showing high "spurious"
signals which are definitely direct related to the base band audio (100-3000
Hz) of the signal you are listening to. It's very tiring to listen to.

I'm right now at the point of testing with an audio analyzing software tool
and will report.

The question now is, what can we do about it?

73's, Evert PA2KW

[Steve Ellington]

Those that have complained about hissy and noisy audio all have one thing in
common....All 3 are in the Netherlands.
Could there be some common thread among residences in this region that
enables one to detect these K3 abnormalities?
Steve Ellington
N4...@carolina.rr.com

[Evert Bakker (PA2KW)]

Are we (dutch) all using the same version of Heil headset?
I never noticed this high hiss with my old Telex headphones (with a smaller
freq-response I guess)

73's, Evert PA2KW

[Wes Stewart]

--- On Sun, 4/5/09, Steve Ellington <n4...@carolina.rr.com> wrote:

> From: Steve Ellington <n4...@carolina.rr.com>
> Subject: Re: [Elecraft] My K3's hissy and noisy audio
> To: ev...@pa2kw.com, "'Maarten van Rossum'" <pd2r.m...@gmail.com>, "'Elecraft Group'" <elec...@mailman.qth.net>
> Cc: "'Gary Surrency'" <sup...@elecraft.com>
> Date: Sunday, April 5, 2009, 11:47 AM
> Those that have complained about hissy and noisy audio all
> have one thing in
> common....All 3 are in the Netherlands.
> Could there be some common thread among residences in this
> region that
> enables one to detect these K3 abnormalities?
> Steve Ellington

Sorry to pop this balloon but I'm in Arizona, USA and I concur.

[Steve Ellington]

The exception proves the rule.

Steve Ellington
N4...@carolina.rr.com
----- Original Message -----
From: "Wes Stewart" <n7...@yahoo.com>
To: <ev...@pa2kw.com>; "'Maarten van Rossum'" <pd2r.m...@gmail.com>;
"'Elecraft Group'" <elec...@mailman.qth.net>; "Steve Ellington"
<n4...@carolina.rr.com>

[Wes Stewart]

--- On Sun, 4/5/09, Steve Ellington <n4...@carolina.rr.com> wrote:

> The exception proves the rule.

And what's that supposed to mean?

[Jack Brindle]

I felt the same thing when I first started using my K3. As I started
learning how to adjust the IF filter controls I found that as the
bandwidth became more optimum I was also able to cut out the super
highs and lows. The K3 can give you a really wide audio frequency
spectrum if you want to hear it. But I have found that for SSB a low
cut of 350 to 450 Hz coupled with a high cut of around 1.75 KHz
provides a very good audio range that does not fatigue my ears. For
contesting I narrow it down even more and still have very copiable
reception.

For CW I vary the width to give similar results, but much more narrow
bandwidth. Hearing high or very low pitched sounds can tire your ears
quickly. My K3 does a great job of eliminating those while still
allowing me to hear what I need. While I am used to closing down the
bandwidth to limit what I hear, the other two hams in my family are
not. Both KB4TGE and KG6YMN have had no problems at all with the
narrow bandwidths. Both are definitely not in the contester category
(yet)...

As others have noted on the list, it seems to be best to adjust the
high and low cuts for SSB, while adjusting the IF bandwidth for CW.
The latter varies the IF frequency, while the high/low cut does not.

And, for the record, my K3 has the stock 2.7 KHz 5-pole filter along
with a 500 Hz 5-pole filter. I use a Heil Proset headset with HC-4 mic
element. I don't yet feel the need for other filters, although I am
sure that will change as the gift-giving season (Christmas, birthday,
etc) approaches and the above-mentioned hams start asking what I might
like... ;-)

The environment of Silicon Valley is very RF-intensive. As one would
expect of a high-technology area, there are a lot of hams, and
contesters, in close proximity. I have found that the best setup for
my K3 in a contest is to run with attenuation ON, preamp OFF, and as
narrow bandwidth as possible. With this combination, I am actually
getting back to not having headaches at the end of a long contest. The
K3 has definitely improved my contest enjoyment.

I think the message here is to experiment with the radio to get what
you want and need from it. It shouldn't be giving you headaches or
extraneous noise unless you really want it to. Once you learn the
magic combination for your operation you should have very enjoyable
operation.

-Jack Brindle, W6FB
=======================================================================

[Steve Ellington]

Meaning: "The exception proves the Rule".
If there is an exception to the rule, then there must be then be a rule.
Since 3 Dutch hear hissing K3s, we have a rule however you being an
exception proves that there must be a rule. Another explanation could be
that perhaps you have some Dutch in the family tree. Stewart may not be a
proper Dutch name however Martha Stewart does market the Martha Stewart
Dutch Oven. One reviewer of this oven mentioned "the steam vent hissing like
a cornered cat". So maybe this is the link we've been looking for thus
absolutely proving the rule that the Dutch hear hissing sounds in their K3s.
Steve Ellington

Steve Ellington
N4...@carolina.rr.com
----- Original Message -----
From: "Wes Stewart" <n7...@yahoo.com>
To: <ev...@pa2kw.com>; "'Maarten van Rossum'" <pd2r.m...@gmail.com>;
"'Elecraft Group'" <elec...@mailman.qth.net>; "Steve Ellington"
<n4...@carolina.rr.com>
Sent: Sunday, April 05, 2009 2:56 PM
Subject: Re: [Elecraft] My K3's hissy and noisy audio

>
>
>
>

[Carl Clawson]

It's commonly misunderstood saying. It uses an almost-obsolete meaning of
the verb "prove" which means "test". (As in "proving grounds.")

The exception tests the rule.

73, Carl WS7L

[ab2tc]

Hi all,

In my view the only "problem" with the K3 being "hissy" is the AGC threshold. On 20m and below even with AGC threshold set to the maximum (008), just the atmospheric noise is at or above the threshold and this is indeed tiring to listen to. I solve the problem by turning down the RF gain; I notice many others instead turn the AGC slope way up (actually low number), which has a similar effect for strong signals. Very high on my wish list is for at least another 5dB increase in the AGC threshold. The present range 002-008 is just not enough.

>Sorry to pop this balloon but I'm in Arizona, USA and I concur.

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elec...@mailman.qth.net

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html

-----
AB2TC - Knut
--
View this message in context: http://n2.nabble.com/My-K3%27s-hissy-and-noisy-audio-tp2588008p2590003.html

Sent from the Elecraft mailing list archive at Nabble.com.

______________________________________________________________

[Steve Ellington]

Perhaps the band noise is more obvious in the K3 because the low frequency
audio is restricted causing the noise to be distributed over a more narrow
range. This lack of bass tends to induce for ear fatigue.

Steve Ellington
N4...@carolina.rr.com
----- Original Message -----

From: "ab2tc" <ab...@arrl.net>
To: <elec...@mailman.qth.net>
Sent: Sunday, April 05, 2009 4:42 PM
Subject: Re: [Elecraft] My K3's hissy and noisy audio

>
>
>
>

[Evert Bakker (PA2KW)]

Hello Jack,

Thanks for all info. I played around a while with the IF_BW controls.
The problem is that the level and sound of the high hiss, isn't depending on
the IF BW. I just tried 50 Hz BW on CW and listening to a stronger signal. I
still hear the same hiss with the same strength and "sound". I also tried
RX-EQ settings. It seems that there is no way, with the exception of the
volume, that I can influence the hiss.

I did blame the "bad audio of the K3". That conclusion is to fast and it
might well be something else (bad headset or even a bad operator). We'll
have to wait and see if someone can help me (us) out.

73's, Evert PA2KW

-----Original Message-----
From: Jack Brindle [mailto:jackb...@earthlink.net]
Sent: Sunday, April 05, 2009 21:55
To: ev...@pa2kw.com
Cc: 'Maarten van Rossum'; 'Elecraft Group'; 'Gary Surrency'
Subject: Re: [Elecraft] My K3's hissy and noisy audio

[Merv Schweigert]

I will also confirm the audio leaves a lot to be desired.
More than just a couple exceptions, perhaps some of
us did not drink the Kool Aide.

[Maarten van Rossum]

Thank you all for the great replies, most were very helpful.

I'll keep you posted once I have experimented some more.

73, Maarten

2009/4/6 Merv Schweigert <k9...@flex.com>

[Eric Scace K3NA]

I have very sensitive in-ear monitors. The K3 (and the Orion, and
possibly other radios) has significant hiss. I inserted an attenuator
and knocked the hiss down below my ability to detect it. There is
plenty of audio range remaining.

You may find 10 to 20 dB will help.

[Stewart Baker]

That's my view as well.

Stewart G3RXQ

[Paul Christensen]

> Perhaps the band noise is more obvious in the K3 because the low frequency
> audio is restricted causing the noise to be distributed over a more narrow
> range. This lack of bass tends to induce for ear fatigue.
> Steve Ellington

I agree with Steve on this one. Once more low-end was rolled into my audio
hardware changes, I noticed a significant reduction in my own listener
fatigue.

Others have noted the K3's audio frequency response variance across
different headphone models, most notably the Heil product. The K3's
headphone circuit uses 10 uF of series capacitance from the headphone amp to
each of the headphone coils.

For the moment, assume that your headphones are 32-ohms (ref 100Hz). What
is the best possible low-end response from the K3? The answer is 500 Hz
@ -3dB. That part of the circuit needs some help. With a headphone Z even
lower toward 8-ohms, the attenuation of bass response is worse.

Now upgrade the series caps to 330 uF and re-run the calculation. With
32-ohm phones (ref 100 Hz), the frequency response improves to 15 Hz. Now
that's t real Hi-Fi on par with what Icom delivers and the difference is
immediately noticeable to anyone -- not just the folks with "golden ears."

Finally, compare the result of the modified K3 with the Icom '7700 or '7800.

Paul, W9AC

[Stewart Baker]

Audio response seems to be a difficult area for Elecraft.
SSB from the K2 often received poor reports because of the
excessive LF response in the TX audio stages.
It could be cured by reducing coupling capacitor values.
The K3 RX audio appears to need the opposite approach.

Stewart G3RXQ

[Ignacy]

AGC settings and AF gain interact. With no signal you may have lots or little audio. Also, full audio can be at 20% of 50% gain.

When looking at the spectrum of a CW signal one clearly see the third and the fifth harmonics. Not sure whether they are real or artifacts of a sound card but K3 sounds a bit harsher than K2. These harmonics were part of a thread here by hams from the UA land; it was followed by the AF mod.. I am not sure whether my radio has already this fix(# around 2200).
Ignacy

--
View this message in context: http://n2.nabble.com/My-K3%27s-hissy-and-noisy-audio-tp2588008p2592780.html

Sent from the Elecraft mailing list archive at Nabble.com.

______________________________________________________________

[Steve Ellington]

Paul
I can see how this mod would improve headphone audio but what about low
frequency audio for the speaker(s)?

Steve Ellington
N4...@carolina.rr.com
----- Original Message -----
From: "Paul Christensen" <w9...@arrl.net>
To: <elec...@mailman.qth.net>
Sent: Monday, April 06, 2009 6:54 AM
Subject: Re: [Elecraft] My K3's hissy and noisy audio

[Paul Christensen]

Steve,

Someone else responded to me in private with the same question. Here's my
answer:

"The K3 speaker output has something like 470 uF of C in series with the
speaker output amp. That's reasonably adequate. The problem with the K3
speaker's bass frequency response is not the electrical circuit. Rather,
the K3's speaker has low-end response limitations due to the fact that the
speaker is in not encased by an adequate baffle. The back wave of any
speaker driven by a coil is 180-degrees out of phase with the forward wave.
Although the K3's speaker is mounted to a metal surface, too many openings
near it allow for the short circuit of the acoustical front and back waves
at low frequencies.

The degree to which acoustical wave cancellation occurs is a function of
distance. At low frequencies, quite a bit of isolation distance is
required. Typically, commercial speakers are encased (although some are
ported to a resonance) to produce a virtual infinite distance through the
use of the so-called infinite baffle.

We've all done this experiment before at some point in our electronics
education: Simply place an open speaker driver on a desk just sitting there
and listen to low frequency tones. Then, take that same speaker and place
it in an enclosure, or behind a large surface. The speaker placed by itself
on the desktop sounds vastly inferior in bass
response when compared to the same speaker enclosed in a box or placed
behind a surface like wall or ceiling.

For the K3, the fix is relatively easy. Simply enclose the back of the
speaker driver with a solid substance like plastic. I used the top of a
spray paint can and modified it slightly to fit around the K3's support
truss."

Incidentally, there's another interesting acoustical mechanism that assists
our brains with bass content. If it were not for this effect, our
perception of low-frequency content would be worse than it is when we listen
to small speakers whose low-end response is restricted. In effect, our
brains create a missing fundamental when it detects the presence of multiple
harmonics of a single fundamental that should be there in the first place.
Among auditory professionals, this effect is referred to as "Phenomenon of
the Missing Fundamental."

http://www.phys.uconn.edu/~gibson/Notes/Section7_4/Sec7_4.htm

Paul, W9AC

[wayne burdick]

Maarten,

If you send me recordings of your K3 audio (and if possible, recordings
of your other rig's audio for comparison), Lyle and I will listen to
them and see if we think there's anything wrong (excessive hiss,
harshness, etc.). This is certainly not the case with my K3 or any of
those I've tested in my lab.

If it turns out that nothing is broken, but that you perceive another
rig to be better in some way, then we will try to improve the K3 to
your satisfaction. Comparative recordings are the first step.

73,
Wayne
N6KR

---

http://www.elecraft.com

[Joe Subich, W4TV]

> Now upgrade the series caps to 330 uF and re-run the
> calculation. With 32-ohm phones (ref 100 Hz), the frequency
> response improves to 15 Hz. Now that's t real Hi-Fi on par
> with what Icom delivers and the difference is immediately
> noticeable to anyone -- not just the folks with "golden ears."

On the other hand, plug a Heil ProSet with its 200 Ohm elements
into an unmodified K3 and the -3dB point is 80 Hz ... low enough
for communications use without being overly sensitive to hum and
other low frequency noise, Similarly, with 8 Ohm speakers, the
-3 dB point is 40 Hz with the 470 uF coupling capacitors in the
speaker amp.

73,

... Joe, W4TV

> -----Original Message-----
> From: elecraft...@mailman.qth.net
> [mailto:elecraft...@mailman.qth.net] On Behalf Of Paul
> Christensen
> Sent: Monday, April 06, 2009 6:54 AM
> To: elec...@mailman.qth.net
> Subject: Re: [Elecraft] My K3's hissy and noisy audio
>
>

[David Ferrington, M0XDF]

Now, you name any other manufacture which would offer that - and
direct from one of the owners of the company. Is that service, or is
that SERVICE?
73 de M0XDF, K3 #174
--
If you're sending someone some Styrofoam, what do you pack it in?

On 6 Apr 2009, at 18:26, wayne burdick wrote:

> Maarten,
>
> If you send me recordings of your K3 audio (and if possible,
> recordings
> of your other rig's audio for comparison), Lyle and I will listen to
> them and see if we think there's anything wrong (excessive hiss,
> harshness, etc.). This is certainly not the case with my K3 or any of
> those I've tested in my lab.
>
> If it turns out that nothing is broken, but that you perceive another
> rig to be better in some way, then we will try to improve the K3 to
> your satisfaction. Comparative recordings are the first step.
>
> 73,
> Wayne
> N6KR

______________________________________________________________

[Maarten van Rossum]

Yes, that is great service!

I was not aware the my question on the reflector would stir thing up the way
it dit. I´m not verry technical and I thought I had some setting messed up
with my K3 which resulted in the bad audio. Given all the great response on
the reflector I´m kind of lost in all the things that could be causing the
less then diserable audio.

In hindsite I feel that maybe it was better to contact Elecraft personaly.
But again, I was not aware that I would lead to this much response.

I am greatfull that Wayne is willing to help me out with this. It might take
a wile before I can get the audio recordings because I´m not quiet sure how
to make those recordings. Making the recordings shouldn´t be that hard,
getting the Icom next to my K3 is a different problem. We use our own
radio´s at our contest station and last time I brought my K3 and another
operator brought his IC-7700. I can make a comparison with a FT 1000D from a
friend who lives nearby.

Thank you Wayne for your offer to sort this out, I´ll try to make the
recordings a.s.a.p.

Best 73

[Maarten van Rossum]

Oeps, forgot to take out the typo´s, pressed the send button to soon. Sorry
about that.

2009/4/7 Maarten van Rossum <pd2r.m...@gmail.com>

[Bryan, ZL1NI]

Using Heil ProSet here and very satisfied with the K3's audio for
communications use.

Bryan, Zl1NI

>
> On the other hand, plug a Heil ProSet with its 200 Ohm elements
> into an unmodified K3 and the -3dB point is 80 Hz ... low enough
> for communications use without being overly sensitive to hum and
> other low frequency noise, Similarly, with 8 Ohm speakers, the
> -3 dB point is 40 Hz with the 470 uF coupling capacitors in the
> speaker amp.
>
> 73,
>
> ... Joe, W4TV

______________________________________________________________

[Bill Tippett]

VR2BG wrote:

>The K3 apparently has the same sort of energy on its audio output,
but because it is so many dB down, when the news broke it was
dismissed as a non-issue.

>Some folks have better hearing than others. Reproduction of the
sound can also vary due to differences in speakers & headphones.
All the variables could add together enough to reach the point where
the effect is noticeable; they just as easily combine to something
less.

>I hope Elecraft looks at issues like this more objectively than its
user community appears to sometimes. And cheers to those who
will say what some don't want to hear, is the only way things can
get sorted out.

I'm sure Wayne will find this problem. The fact that many
variables may be involved seems to be causing some to experience it and
others not (luckily I'm one of the latter). The key is to get some good
recordings and forward them to Elecraft with detailed setup descriptions
including external devices (headphones, speakers, etc). Once the
problem can be quantified, I'm sure the solution will come very quickly.

73, Bill W4ZV

[Paul Christensen]

> On the other hand, plug a Heil ProSet with its 200 Ohm elements
> into an unmodified K3 and the -3dB point is 80 Hz ... low enough
> for communications use without being overly sensitive to hum and

> other low frequency noise...

That would be a good choice for the stock K3. One thing to note is that
most coil-based headphones and speaker elements do not have a flat impedance
curve as a function of frequency. Some can vary considerably from their
rated impedance rating. The Z at 50 Hz can be vastly different than at 5
kHz.

Also, moving the C9 & C13 headphone coupling capacitors up in value will
allow for grabbing most any headphones.without worry as to how response will
be affected. I used an old set of Koss Pro4/AA for testing but use
Sennheiser PCX300 or Bose Triports headphones when operating my K3.