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OT - sound cards

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K7TV

OT - sound cards

Joe, thanks for those comments. You seem to have spent a lot of time looking
into these issues. Jim Brown said something about your business. Would I go
too far OT if I asked in what business context you look at sound cards?

73,

Erik K7TV

Joe Subich wrote:

Correct ... that $30 USB headset is a $0.05 electret capsule and a $2.00 USB
audio chip (C-Media or TI/Burr Brown). The best thing in the world is to do
the A/D from a higher level signal (23-26 dB more drive) and power the
device from the relatively "clean" USB power away from the multiple amp
digital supplies with their 600 to 800 MHz noise.

I used to argue that the internal sound card was fine and in the early days
with microHAM we actually tested many sound cards and motherboards which had
good dynamic range (low noise floors). But recently - mainboards are being
designed with very little regard to decoupling and routing of audio signals.
The on board sound systems are being placed for ease of connecting to the
system bus or PCI bridge controllers which often means long audio runs in a
very noisy environment. When that is coupled with a dynamic mic, and 20 dB
of gain boost in the mic circuit of the sound chip it is easy to see why the
mic inputs are so dirty (and the soundcard dynamic range drops to less than
60 dB! from about 96 dB for a good

16 bit A/D).

73,

... Joe, W4TV

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David Gilbert

Re: OT - sound cards

In reply to this post by K7TV

Yup .. you're right. I went back and checked your original message, and
while you mentioned using the sound card for digital modes and talked
about having trouble making voice recordings with it, you never said
anything about the voice recordings being for ham radio. I erroneously
made that connection and came to the wrong conclusion. Sorry for the
added confusion.

Dave AB7E

On 1/9/2012 6:54 PM, Erik Basilier wrote:

> Dave,
>
> Please understand that my audio recording need has nothing to do with my K3
> or with ham radio. The USB/RS232 line connecting the computer with the K3 is
> there, but the K3 is powered down. And I have no bonding between the chassis
> of the two. I never had a problem, but then I never tried to record radio
> output on the computer, and I never tried to feed a computer voice recording
> to the K3. I have done some PSK, using a previous desktop computer as well
> as the old laptop, but then I was always using a homebuilt interface that
> contains isolation transformers. Yes I know, overkill, but that interface
> was built before I got the K3. I am currently not interested in doing PSK or
> other digital modes again, but when I get the urge, I will probably have
> purchased an external soundcard that will be better than the current
> computer's motherboard-integrated audio. Just for fun, because you seem to
> focus on it, I made an experiment: I disconnected the RS-232 from the
> computer by unplugging its USB. Then I made a recording using a dynamic
> microphone and found the same noise as before. The powered speakers were
> disconnected from the computer during the recording. Still connected were
> other items such as monitor, keyboard, mouse, two printers and wired
> Ethernet. It would certainly be possible to test with more stuff
> disconnected, but that is all I have time for right now.
>
> When you mention twang on the audio, I assume you were recording the audio
> on the computer while using the noise reduction associated with its
> microphone input? That is the only condition under which I hear the twang
> (and then it replaces the noise). If I turn the noise reduction off, the
> twang disappears and the noise comes back.
>
> Erik K7TV
>
>
>
> David Gilbert wrote:
>
>
>
> OK, now that sounds a lot like the issues I had when I first began using
> pre-recorded .wav files for contesting. I got several reports of "hum",
> "noise", or "whine" on my transmitted signal ... all of which went away when
> I disconnected the RS-232 cable from between the computer and the K3. As I
> have mentioned several times here before, it took a very short piece of
> shielded braid between the chassis of the K3 and the chassis of the computer
> to fix it so that I could reconnect the RS-232 cable without issues. I
> started with a couple of feet of braid and had to go all the way down to
> eight inches before I could no longer notice the problem.
>
> You don't say what measures you've taken to bond the chassis of your K3 to
> your computer, but that would be my first suggestion. Your symptoms sound
> almost identical ... even with respect to the noise during pauses and the
> metallic twang at the end of words.
>
> Regarding sound cards for SDR use, certainly the great majority of cards out
> there would have major deficiencies ... most especially for noise, but also
> for dynamic range and sampling rate. And as you say, many don't even have
> stereo inputs. N8LP keeps a list of recommended cards on his web site with
> good information on the pros and cons of each.
>
> 73,
> Dave AB7E
>
>
>
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Mike Reublin

Re: OT - sound cards

In reply to this post by k6dgw

While the connector is a good bet, I can't help but wonder it it's attached to a
"chassis" inside. The Mac bottom comes off easily enough. I took it off to upgrade
memory. I'm surprised Apple made it that easy.

73, Mike NF4L

On 1/9/2012 5:37 PM, Fred Jensen wrote:

> On 1/9/2012 2:00 PM, Mike wrote:
>> How does one bond a flaptop? Most of the Win machines I've seen have a plastic case.
>> My Macbook Pro has a metal case, but the screws that hold the bottom cover are tiny.
> It can be hard to find metal. My laptop has a DB-15F for an external
> monitor or projector on the side, and I get a chassis connection there
> using a short screw in one of the two tie-down nuts. Seems to work fine.
>
> FWIW: Youngest son and family gave me the Steve Jobs biography for
> Christmas. I'm about half way through, but far enough to understand
> that Jobs very specifically intended that users not be able to take the
> Mac apart, to the extent that they used some screws that required a
> special tool. Don't know about the Macbook Pro, but if I had one, I
> don't think I'd take the screws out. He was pretty paranoid about this
> ... it might self-destruct. :-)
>
> 73,
>
> Fred K6DGW
> - Northern California Contest Club
> - CU in the 2012 Cal QSO Party 6-7 Oct 2012
> - www.cqp.org
>
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Mike Reublin

Re: OT - sound cards

In reply to this post by alorona

Neither of the flaptops (Toshiba & Mac) have a connector that has any way to attach a
wire to (like a DB-9), and neither has a cable lock point. :-(

73, Mike NF4L

On 1/9/2012 5:40 PM, Al Lorona wrote:

> Shell of one of the metal connectors; or use a cable in the cable-lock jack.
>
>
>> How does one bond a flaptop?
>> 73, Mike NF4L
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Bruce Beford-2

Re: OT - sound cards

In reply to this post by K7TV

Could you carefully solder a wire to the shell of a USB plug to use as a
bonding point?
73,
Bruce, N1RX

> Neither of the flaptops (Toshiba & Mac) have a connector that has any way
> to attach a wire to (like a DB-9), and neither has a cable lock point. :-(

> 73, Mike NF4L

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Mike Reublin

Re: OT - sound cards

Maybe some could, but I don't think I could. It would have to be right next to the
plastic/rubber cover.

73, Mike NF4L

On 1/10/2012 6:20 AM, Bruce Beford wrote:

> Could you carefully solder a wire to the shell of a USB plug to use as a
> bonding point?
> 73,
> Bruce, N1RX
>
>> Neither of the flaptops (Toshiba& Mac) have a connector that has any way
>> to attach a wire to (like a DB-9), and neither has a cable lock point. :-(
>> 73, Mike NF4L
>
>
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David Windisch

Re: OT - sound cards

This post was updated on .

In reply to this post by Bruce Beford-2

CONTENTS DELETED

The author has deleted this message.

Brgds,
Dave, N3HE
Cincinnati OH

WE5ST

Re: OT - sound cards

Anyone have a source for Sal-Met? I can't find it on the web.

________________________________
From: David Windisch <[hidden email]>
To: [hidden email]
Sent: Tue, January 10, 2012 6:23:16 AM
Subject: Re: [Elecraft] OT - sound cards

Could you carefully solder a wire to the shell of a USB plug to use as a
bonding point?
73,
Bruce, N1RX

Btdt: use SAL-MET flux after carefully filing/scraping a target bare spot
on the shell. XACTO the boot carefully if needed to expose a target spot.
SAL-MET works on every substance I've attempted, including stainless steel.
I've kept the same bottle of the stuff around since the '60s when I bought
it. Algalw.
Brgds,
Dave, N3HE

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Jack - WE5ST

Eric Swartz - WA6HHQ

Re: OT - sound cards

Administrator

In reply to this post by David Windisch

We're hitting the single topic posting limit. Let's wind this thread down this morning.

73,
Eric
List Manager
www.elecraft.com
_..._

On Jan 10, 2012, at 4:23 AM, David Windisch <[hidden email]> wrote:

>
> Could you carefully solder a wire to the shell of a USB plug to use as a
> bonding point?
> 73,
> Bruce, N1RX
>
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