LINE OUT output too low?
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Hello everyone! Greetings from northeast of Brazil! I think this topic has somehow been discussed before but it was not conclusive. Forgive-me in case I´m wrong. While trying to make audio recordings using the K3 line level output and my Marantz PMD620 handheld audio recorder (http://www.d-mpro.eu.com/index2.php?CID=3&Pid=139&action=detail&lang=eng) I found out that the output level of the/my K3 (#1164) is not high enough to make a good recording, no matter I turn the CONFIG LINE OUT to 100%.
I´ve used the same Marantz recorder many times, plugged in others receivers/transceivers, and most of the times I´ve to attenuate the input level to avoid overload and distortion.
Is something wrong with my K3? Can the AF stage upgrade help me with that? According to the K3 project, what is the nominal line level output of the K3? Thanks in advance. André Santos, PT7AT _______________________________________________ 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 |
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Andre,
I have not measured the K3 line out signal level - it does depend on the input signal level to the antenna. However, it should work fine with most recording devices, unless that device presents a low impedance input (which would require more driving power). You could try reducing the series resistors on the input side of the isolation transformers (see page 8 of the K3AFMDKT instructions) which may help. The mod kit addresses distortion, but should also help to increase the output level. 73, Don W3FPR André Santos wrote: > > Hello everyone! Greetings from northeast of Brazil! > > I think this topic has somehow been discussed before but it was not > conclusive. Forgive-me in case I´m wrong. > > While trying to make audio recordings using the K3 line level output > and my Marantz PMD620 handheld audio recorder > (http://www.d-mpro.eu.com/index2.php?CID=3&Pid=139&action=detail&lang=eng > <http://www.d-mpro.eu.com/index2.php?CID=3&Pid=139&action=detail&lang=eng>) > I found out that the output level of the/my K3 (#1164) is not high > enough to make a good recording, no matter I turn the CONFIG LINE OUT > to 100%. > > I´ve used the same Marantz recorder many times, plugged in others > receivers/transceivers, and most of the times I´ve to attenuate the > input level to avoid overload and distortion. > > Is something wrong with my K3? Can the AF stage upgrade help me with > that? According to the K3 project, what is the nominal line level > output of the K3? > > Thanks in advance. > > André Santos, PT7AT > > ------------------------------------------------------------------------ > > _______________________________________________ > 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 > ------------------------------------------------------------------------ > > > No virus found in this incoming message. > Checked by AVG - http://www.avg.com > Version: 8.0.176 / Virus Database: 270.9.18/1848 - Release Date: 12/14/2008 12:28 PM > > 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 |
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Thanks Don!
I was planning to make the audio mod anyway. It might help to increase the output level even a little bit. The actual output level (or amplification) for some reason is well below the standard for line outs. Elecraft should address this problem. Otherwise, I think the K3 is a fantastic transceiver. The best one I have ever had. 73, André, PT7AT
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IF I remember correctly, when you choose line out from the mail menu,
the MON pot adjusts the level. It then remembers it. 73 de M0XDF, K3 #174 -- Hofstadter's Law: The time and effort required to complete a project are always more than you expect, even when you take into account Hofstadter's Law. On 16 Dec 2008, at 15:03, André Santos wrote: > > Thanks Don! > > I was planning to make the audio mod anyway. It might help to > increase the > output level even a little bit. > > The actual output level (or amplification) for some reason is well > below the > standard for line outs. Elecraft should address this problem. > > Otherwise, I think the K3 is a fantastic transceiver. The best one I > have > ever had. > > 73, > > André, PT7AT > > > > Don Wilhelm-4 wrote: >> >> Andre, >> >> I have not measured the K3 line out signal level - it does depend >> on the >> input signal level to the antenna. >> However, it should work fine with most recording devices, unless that >> device presents a low impedance input (which would require more >> driving >> power). >> >> You could try reducing the series resistors on the input side of the >> isolation transformers (see page 8 of the K3AFMDKT instructions) >> which >> may help. The mod kit addresses distortion, but should also help to >> increase the output level. >> >> 73, >> Don W3FPR >> >> André Santos wrote: >>> >>> Hello everyone! Greetings from northeast of Brazil! >>> >>> I think this topic has somehow been discussed before but it was not >>> conclusive. Forgive-me in case I´m wrong. >>> >>> While trying to make audio recordings using the K3 line level output >>> and my Marantz PMD620 handheld audio recorder >>> (http://www.d-mpro.eu.com/index2.php?CID=3&Pid=139&action=detail&lang=eng >>> <http://www.d-mpro.eu.com/index2.php?CID=3&Pid=139&action=detail&lang=eng >>> >) >>> I found out that the output level of the/my K3 (#1164) is not high >>> enough to make a good recording, no matter I turn the CONFIG LINE >>> OUT >>> to 100%. >>> >>> I´ve used the same Marantz recorder many times, plugged in others >>> receivers/transceivers, and most of the times I´ve to attenuate the >>> input level to avoid overload and distortion. >>> >>> Is something wrong with my K3? Can the AF stage upgrade help me with >>> that? According to the K3 project, what is the nominal line level >>> output of the K3? >>> >>> Thanks in advance. >>> >>> André Santos, PT7AT >>> >>> ------------------------------------------------------------------------ >>> >>> _______________________________________________ >>> 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 >>> ------------------------------------------------------------------------ >>> >>> >>> No virus found in this incoming message. >>> Checked by AVG - http://www.avg.com >>> Version: 8.0.176 / Virus Database: 270.9.18/1848 - Release Date: >>> 12/14/2008 12:28 PM >>> >>> >> _______________________________________________ >> 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 >> >> > > -- > View this message in context: http://n2.nabble.com/LINE-OUT-output-too-low--tp1656257p1663210.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 _______________________________________________ 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 |
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In reply to this post by André Santos
>>> Is something wrong with my K3? Can the AF stage upgrade help me with
>>> that? According to the K3 project, what is the nominal line level >>> output of the K3? On my K3, with the AFMODKT changes in place on the KIO3 board, and driving an open circuit, I get up to 600 mV p-p of audio output if LINE OUT is set to 100 while listening to a moderately strong signal with AGC activated. This of course depends on the signal strength, AGC settings and so forth. A typical output level is less, since the LINE OUT is normally set much lower than 100. 73, Lyle KK7P _______________________________________________ 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 |
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On Tue, 16 Dec 2008 13:16:28 -0800, Lyle Johnson wrote:
>On my K3, with the AFMODKT changes in place on the KIO3 board, and >driving an open circuit, I get up to 600 mV p-p of audio output if LINE >OUT is set to 100 while listening to a moderately strong signal with AGC >activated. This of course depends on the signal strength, AGC settings >and so forth. >A typical output level is less, since the LINE OUT is normally set much >lower than 100. Consumer line level ins and outs are designed to handle levels corresonding to a sine wave of at least 1V. 1.4v peak, 2.8v p-p. 600mV p-p is 13 dB below that. So yes, I agree with the guy who says that the Line Out level is pretty low. Sorta like a hot mic level. :) Now, audio is dynamic, and except for CW, is almost never a sine wave. Rather, it's dynamic, with its level varying widely depending on program. The RMS value of unprocessed (no compression or limiting) speech and music is typically 14 dB below the peak level. But think of it this way -- the audio circuitry has to be able to handle ALL the voltage in the audio stream, including all the noise and QRM, and most of that noise is very "spiky" -- that is, their peaks are often 20-30 dB hotter than their average value, and those peaks can clip and create distortion long before the signal distorts, making the audio a real mess. Bottom line -- an audio output stage for a communications RX needs a lot of headroom. 73, Jim K9YC _______________________________________________ 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 |
RE: LINE OUT output too low?
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> Consumer line level ins and outs are designed to handle levels > corresonding to a sine wave of at least 1V. 1.4v peak, 2.8v > p-p. 600mV p-p is 13 dB below that. So yes, I agree with the > guy who says that the Line Out level is pretty low. Sorta like > a hot mic level. :) Unfortunately, amateur manufacturers have never used the consumer definition of "line level." Every manufacturer seems to have a different definition for both level and impedance ... from 100 mV at 50K to 4V p-p at 600 Ohms. With the AF output mod (47 Ohms in series with the primary of the Line Out transformers), the K3's Line Out looks reasonably clean at 1V or more of audio. Prior to the change, harmonic distortion got fairly bad above 600 mV p-p. The absolute audio level is highly dependent on AGC settings - or the gain reduction caused by AGC action. 73, ... Joe, W4TV > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Jim Brown > Sent: Tuesday, December 16, 2008 7:25 PM > To: [hidden email] > Subject: Re: [Elecraft] LINE OUT output too low? > > > On Tue, 16 Dec 2008 13:16:28 -0800, Lyle Johnson wrote: > > >On my K3, with the AFMODKT changes in place on the KIO3 board, and > >driving an open circuit, I get up to 600 mV p-p of audio > output if LINE > >OUT is set to 100 while listening to a moderately strong signal with > AGC > >activated. This of course depends on the signal strength, > AGC settings > >and so forth. > > >A typical output level is less, since the LINE OUT is > normally set much > >lower than 100. > > Consumer line level ins and outs are designed to handle levels > corresonding to a sine wave of at least 1V. 1.4v peak, 2.8v > p-p. 600mV > p-p is 13 dB below that. So yes, I agree with the guy who > says that the > Line Out level is pretty low. Sorta like a hot mic level. :) > > Now, audio is dynamic, and except for CW, is almost never a > sine wave. > Rather, it's dynamic, with its level varying widely depending on > program. The RMS value of unprocessed (no compression or limiting) > speech and music is typically 14 dB below the peak level. But > think of > it this way -- the audio circuitry has to be able to handle ALL the > voltage in the audio stream, including all the noise and QRM, > and most > of that noise is very "spiky" -- that is, their peaks are > often 20-30 dB > hotter than their average value, and those peaks can clip and create > distortion long before the signal distorts, making the audio a real > mess. Bottom line -- an audio output stage for a > communications RX needs > a lot of headroom. > > 73, > > Jim K9YC > > > _______________________________________________ > 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 _______________________________________________ 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 |
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FWIW, standard Line Out is 1Vp-p at 600 ohms line impedance.
matt On Wed, 17 Dec 2008 01:01:51 -0500, you wrote: > > >> Consumer line level ins and outs are designed to handle levels >> corresonding to a sine wave of at least 1V. 1.4v peak, 2.8v >> p-p. 600mV p-p is 13 dB below that. So yes, I agree with the >> guy who says that the Line Out level is pretty low. Sorta like >> a hot mic level. :) > >Unfortunately, amateur manufacturers have never used the consumer >definition of "line level." Every manufacturer seems to have a >different definition for both level and impedance ... from 100 mV >at 50K to 4V p-p at 600 Ohms. > >With the AF output mod (47 Ohms in series with the primary of the >Line Out transformers), the K3's Line Out looks reasonably clean >at 1V or more of audio. Prior to the change, harmonic distortion >got fairly bad above 600 mV p-p. > >The absolute audio level is highly dependent on AGC settings - or >the gain reduction caused by AGC action. > >73, > > ... Joe, W4TV > > > > > >> -----Original Message----- >> From: [hidden email] >> [mailto:[hidden email]] On Behalf Of Jim Brown >> Sent: Tuesday, December 16, 2008 7:25 PM >> To: [hidden email] >> Subject: Re: [Elecraft] LINE OUT output too low? >> >> >> On Tue, 16 Dec 2008 13:16:28 -0800, Lyle Johnson wrote: >> >> >On my K3, with the AFMODKT changes in place on the KIO3 board, and >> >driving an open circuit, I get up to 600 mV p-p of audio >> output if LINE >> >OUT is set to 100 while listening to a moderately strong signal with >> AGC >> >activated. This of course depends on the signal strength, >> AGC settings >> >and so forth. >> >> >A typical output level is less, since the LINE OUT is >> normally set much >> >lower than 100. >> >> Consumer line level ins and outs are designed to handle levels >> corresonding to a sine wave of at least 1V. 1.4v peak, 2.8v >> p-p. 600mV >> p-p is 13 dB below that. So yes, I agree with the guy who >> says that the >> Line Out level is pretty low. Sorta like a hot mic level. :) >> >> Now, audio is dynamic, and except for CW, is almost never a >> sine wave. >> Rather, it's dynamic, with its level varying widely depending on >> program. The RMS value of unprocessed (no compression or limiting) >> speech and music is typically 14 dB below the peak level. But >> think of >> it this way -- the audio circuitry has to be able to handle ALL the >> voltage in the audio stream, including all the noise and QRM, >> and most >> of that noise is very "spiky" -- that is, their peaks are >> often 20-30 dB >> hotter than their average value, and those peaks can clip and create >> distortion long before the signal distorts, making the audio a real >> mess. Bottom line -- an audio output stage for a >> communications RX needs >> a lot of headroom. >> >> 73, >> >> Jim K9YC >> >> >> _______________________________________________ >> 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 > >_______________________________________________ >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 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 |
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In reply to this post by André Santos
That may or may not be the case but it is more than ample to drive a sound card input. To drive my sound card without overload I only need the line out level set to about 4. The problem is worse for those who use laptops because most new laptops appear not to have a line input at all, only a microphone input which of course is a lot more sensitive and requires even less signal from the K3.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
Re: LINE OUT output too low?
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In reply to this post by Matt Zilmer
> "FWIW, standard Line Out is 1Vp-p at 600 ohms line impedance. matt"
I think you'll find standard, nominal "Line-In/Out" consumer levels to be referenced to -10 dBV irrespective of Z, where 0dBV = 1 Vrms. This standard started with the old IHF, merged into EIA, and then somewhere along the way I believe AES became the recognized standard-setting organization in North America. K9YC would know for sure. -10 dBV is equivalent to 0.316 Vrms. If we assume a worst-case 10 dB peak-to-average ratio (and probably a lot less depending on the K3's AGC menu settings), then the maximum distortion-free signal voltage handling required is 0 dBV or 1 Vrms or 2.83 Vp-p. Paul, W9AC _______________________________________________ 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 |
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In reply to this post by Julian, G4ILO
In the past, it was suggested that folks add a T or Pi attenuator to
bring the level down. I build two 13 dB T attenuators for 600 ohms, and this worked fine - one for MIC IN and the other for SPKR OUT - this is on a laptop. Housing them (inline) in micro-miniature plastic housings once used for a Magellan GPS PIFA antenna. Doing this allowed much finer control over levels than I had before. I had to run Line In at 2 - which for PSK or other data modes leaves no control "space" at all. Now I can run it at 14 or 15, which is just right. 73, matt zilmer, W6NIA k3 # 24 On Wed, 17 Dec 2008 02:42:10 -0800 (PST), you wrote: > > > >André Santos wrote: >> >> >> The actual output level (or amplification) for some reason is well below >> the standard for line outs. Elecraft should address this problem. >> >> > >That may or may not be the case but it is more than ample to drive a sound >card input. To drive my sound card without overload I only need the line out >level set to about 4. The problem is worse for those who use laptops because >most new laptops appear not to have a line input at all, only a microphone >input which of course is a lot more sensitive and requires even less signal >from the K3. > >----- >Julian, G4ILO. K2 #392 K3 #222. >http://www.g4ilo.com/ G4ILO's Shack http://www.ham-directory.com/ Ham >Directory http://www.g4ilo.com/kcomm.html KComm for Elecraft K2 and K3 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 |
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In reply to this post by P.B. Christensen
On Wed, 17 Dec 2008 07:28:32 -0500, Paul Christensen wrote:
>> "FWIW, standard Line Out is 1Vp-p at 600 ohms line impedance. matt" >I think you'll find standard, nominal "Line-In/Out" consumer levels to be >referenced to -10 dBV irrespective of Z, where 0dBV = 1 Vrms. Yes. 600 ohms has not been part of audio practice, pro or consumer, for at least 40 years. ALL line level and mic level audio circuits, pro and consumer, are low impedance source, high impedance termination. The signal is transferred as a voltage, not as power or current. Typical output impedances are on the order of 100 ohms, input impedances are typically 10K for pro line level, 50K for consumer line level. 100 ohms is chosen primarily because it is a good value for isolation of op amps from the capacitance of the cable that it drives. This capacitance can be significant in pro installations, but rarely in consumer applications. >This standard started with the old IHF, merged into EIA, and then >somewhere along the way I believe AES became the recognized >standard-setting organization in North America. K9YC would know I can't speak to the history of these standards, but The AES Standards Committee is an international body, of which I am a member. >-10 dBV is equivalent to 0.316 Vrms. If we assume a worst-case 10 dB >peak-to-average ratio (and probably a lot less depending on the K3's AGC >menu settings), then the maximum distortion-free signal voltage handling >required is 0 dBV or 1 Vrms or 2.83 Vp-p. Yes. For those who are interested, there's more on this in the tutorials on my website. http://audiosystemsgroup.com/publish 73, Jim Brown K9YC _______________________________________________ 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 |
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Thanks, both Paul and Jim for this information. Very useful and I'll
update my knowledge base with it! 73, matt On Wed, 17 Dec 2008 08:45:53 -0800, you wrote: >On Wed, 17 Dec 2008 07:28:32 -0500, Paul Christensen wrote: > >>> "FWIW, standard Line Out is 1Vp-p at 600 ohms line impedance. matt" > >>I think you'll find standard, nominal "Line-In/Out" consumer levels to be >>referenced to -10 dBV irrespective of Z, where 0dBV = 1 Vrms. > >Yes. 600 ohms has not been part of audio practice, pro or consumer, for at >least 40 years. ALL line level and mic level audio circuits, pro and >consumer, are low impedance source, high impedance termination. The signal >is transferred as a voltage, not as power or current. Typical output >impedances are on the order of 100 ohms, input impedances are typically >10K for pro line level, 50K for consumer line level. 100 ohms is chosen >primarily because it is a good value for isolation of op amps from the >capacitance of the cable that it drives. This capacitance can be >significant in pro installations, but rarely in consumer applications. > >>This standard started with the old IHF, merged into EIA, and then >>somewhere along the way I believe AES became the recognized >>standard-setting organization in North America. K9YC would know > >I can't speak to the history of these standards, but The AES Standards >Committee is an international body, of which I am a member. > >>-10 dBV is equivalent to 0.316 Vrms. If we assume a worst-case 10 dB >>peak-to-average ratio (and probably a lot less depending on the K3's AGC >>menu settings), then the maximum distortion-free signal voltage handling >>required is 0 dBV or 1 Vrms or 2.83 Vp-p. > >Yes. > >For those who are interested, there's more on this in the tutorials on my >website. http://audiosystemsgroup.com/publish > >73, > >Jim Brown K9YC > > >_______________________________________________ >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 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 |
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In reply to this post by Jim Brown-10
600ohms still seems to be the practice for ship and aircraft intercoms that
I've come across recently. David G3UNA > > Yes. 600 ohms has not been part of audio practice, pro or consumer, for at > least 40 years. ALL line level and mic level audio circuits, pro and > consumer, are low impedance source, high impedance termination. The signal > is transferred as a voltage, not as power or current. Typical output > impedances are on the order of 100 ohms, input impedances are typically > 10K for pro line level, 50K for consumer line level. 100 ohms is chosen > primarily because it is a good value for isolation of op amps from the > capacitance of the cable that it drives. This capacitance can be > significant in pro installations, but rarely in consumer applications. > > > For those who are interested, there's more on this in the tutorials on my > website. http://audiosystemsgroup.com/publish > > 73, > > Jim Brown K9YC > > 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 |
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In reply to this post by Matt Zilmer
Paul, Jim and everybody else:
The discursion about mVs has been excellent and pretty much instructive but all I'd like to know is why I can use my handheld Marantz recorder with every single radio in my shack that has a line level audio output but I can't use it with my K3! There is something else: when I plug a stereo cable from the k3's line out to the recorder's line in I have to change the recorder's input settings to MONO because with STEREO there is signal only on the left channel. Ok, the right channel is supposed to be used by the sub-receiver. But what if the sub-receiver is not installed? Just as additional info, I have here a Eton E1 receiver and it has line level out/in. It's manual (specifications) says: "Line Audio Output: 300 mV, 1K ohms for each output (left/right)." "Line Audio Input: 300 mV, 47K ohms." 73s André, PT7AT
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In reply to this post by David Cutter
On Wed, 17 Dec 2008 19:38:34 -0000, David Cutter wrote:
>600ohms still seems to be the practice for ship and aircraft intercoms that >I've come across recently. Maybe, maybe not. Often the people the write the data sheets are marketing dweebs, and have no technical background. I don't know anything about aircraft electronics practices. My observations are based on actual measurements of input and output impedances, and/or studying the schematics. Often, a data sheet says 600 ohms and all that they mean is that the output stage can be loaded with 600 ohms and meet its specs. When you measure it, you find a 100 ohm output impedance. Often, a data sheet will say 600 ohms because the marketing dweeb (or even the engineer) thinks that pro stuff is 600 ohms. It is not, and has not been since the days when tubes ruled. It's also common for engineers in industries unrelated to audio (like RF and vdieo) to apply transmission line methods to audio. That, of course, is completely inappropriate. The only audio circuits that are long enough to behave as transmission lines are VERY long telephone lines. At audio frequencies, the characteristic impedance of ANY practical transmission line is complex (that is, R + jX), and varies widely with frequency. There's a tutorial about this on my website. 73, Jim K9YC _______________________________________________ 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 |
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In reply to this post by André Santos
On Wed, 17 Dec 2008 16:21:43 -0800 (PST), Andr+ª Santos wrote:
>why I can use my handheld Marantz recorder with >every single radio in my shack that has a line level audio output but I >can't use it with my K3 Pull up the schematics on the internet and study how the jacks are wired. 73, Jim K9YC _______________________________________________ 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 |
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