Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
I am a CW operator for over 30 years, first professionally and now only as hobby. My measuring instruments are my ears and the operation of the K3. I never had such a good receiver but at first disliked the audio a bit. It was written in many postings and many of you gave a thorough technical explanation even with different 'colors' of the noise. Still I trusted on my ears as a judge and i can say that the new release very much improves the way of listening to CW, SSB and AM signals. The K3 now can really sound the way I like a communications receiver to do. It is just a bit 'warmer' sound than before that makes listening more comfortable and less tiring. I still have no clue about the best NR setting. It would make sense to have some background for which situation which setting is developed. Also I sometimes wonder why there is no full decoupling possibility with DSP technology, meaning what I hear in my headphone is only a clean sinus of 600 Hz, generated by the DSP based on its input . Is this strange thinking for CW, or technically impossible? (No immediate feature request ;). Anyway, thanks for all the good work and 3.33 is an improvement again. Compliments for all the development work being done. I am still proud to operate a K3. Dick PA3CW -- View this message in context: http://n2.nabble.com/K3-Audio-Response-Version-3-33-Firmware-tp3673422p3694016.html Sent from the [K3] mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
I added computer speakers to my K3 (original C9C13). It is like having a new radio. The audio is crisp, loud and much more undesrtandable. With 3.33., I am hearing all that basses generated by audio gurus. As an extra bonus the headphones plugged in the speakers have stronger sound as well. As a negative, there is some RF pickup. Ignacy -- View this message in context: http://n2.nabble.com/K3-Audio-Response-Version-3-33-Firmware-tp3673422p3687001.html Sent from the [K3] mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
On Mon, 21 Sep 2009 10:32:27 -0700 (PDT), Ignacy wrote: I am hearing all that basses generated by audio gurus. The word guru implies authoritative knowledge. Those who try to turn their ham station into a hi-fi rig are simply misguided. In a speech to a ham convention, retired FCC enforcement chief Riley Hollingsworth stated that such things were out of place on the ham bands and that they should simply get a job in a broadcast station if they wanted to do that kind of thing. Most hams who really DO know audio limit their audio bandwidth so that their transmitter runs more efficiently and cuts through noise and QRM better. For the same reason, they also use good dynamics processing of the same sort that is widely used by broadcasters. Those who transmit all that bass are wasting at least half of their transmit power! Those that transmit extended HF response are selfishly using more bandwidth and generating more QRM to their fellow hams. As a negative, there is some RF pickup. Speakers with built-in amplifiers are notorious for RFI. I often tour the aisles at audio trade shows with a THF6A VHF/UHF talkie. In ten years, I've seen only one amplified loudspeaker that didn't pick up RF. It cost about $1,500 and was made in Europe. 73, Jim Brown K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
The word guru implies authoritative knowledge. Those who try to turn their ham station into a hi-fi rig are simply misguided. Perhaps different set of interests would be more appropriate. I do not consider myself misguided in the least, thank you very much. In a speech to a ham convention, retired FCC enforcement chief Riley Hollingsworth stated that such things were out of place on the ham bands and that they should simply get a job in a broadcast station if they wanted to do that kind of thing. And that means what? Most hams who really DO know audio limit their audio bandwidth so that their transmitter runs more efficiently and cuts through noise and QRM better. Indeed. It may cut through better, but if you can't understand what's being said, what good does cutting through do. Those that transmit extended HF response are selfishly using more bandwidth and generating more QRM to their fellow hams. Well, yes -- in the middle of a crowded band or contest or whatever. No one sense there should be a lack of common sense about what constitutes good operating practice. But good operating practice is very dependent on time and place. Unless of course it's the guys over driving their amps with their politely limited bandwidth screaming CQ DX so they can be heard all over the band at once :-) Grant/NQ5T __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
Jim, K9YC, wrote: Speakers with built-in amplifiers are notorious for RFI. I often tour the aisles at audio trade shows with a THF6A VHF/UHF talkie. In ten years, I've seen only one amplified loudspeaker that didn't pick up RF. It cost about $1,500 and was made in Europe. --- Ha! Bet the vendors loved your test ;-) I've tried a couple of different computer speakers as well as conventional bookshelf audio system speakers on my K3 and have found no need for using an auxiliary amplifier. The K3 has plenty of audio power to drive external speakers in almost any Hamshack. I'm currently using a pair of LabTec computer speakers that bypass the internal amplifier by simply disconnecting the wall wart that supplies the amplifier. Ignacy, you might try that and see if they work without powering the internal amp. As Jim observes, the ancient ones (and most hams today) don't limit their audio response out of ignorance or because they couldn't. They knew that bass takes lots of power and generally interferes with intelligibility, especially in us guys. Not only do low frequencies hog power as Jim noted, they are hardly modulated when we produce speech. Our mouths and lips mostly modulate the higher harmonics, typically above 300 Hz. The fundamental tone and low-order power-hogging harmonics produced by our vocal cords are just a drone with little variation other than starting and stopping. Personally, I find that many modern SSB rigs do limit the high frequencies too much. For me, there's a big improvement in intelligibility between rolling off the highs quickly at 2.5 KHz and allowing a full 2.7 to 3.0 kHz through. 3.0 kHz was the standard communications upper frequency roll-off for many years going back through the AM days, and I find it's still preferable to me. A major difference today is that back then we simply rolled off the upper frequencies with the very simplest audio filtering - often just using bypass capacitors in the audio stages that tended to attenuate highs. The result was substantial audio energy being transmitted well above 3 kHz. Nowadays we have the filters to limit high frequencies much better. I understand that there's good evidence that, when digging for a signal in the noise, a lower upper-frequency limit can provide better communications (provided the lows below 300 Hz or so are also attenuated). It's a matter of concentrating the finite amount of RF into the most effective part of the audio spectrum. I find such pinched audio tiring to listen to for any amount of time, and losing the higher frequencies makes many phonemes harder to decode, perhaps because of the US Army's special gift to me (tinnitus from firing too many rounds from my M1 rifle parked next to my ear - our steel helmets don't come with ear protectors). Perhaps before long we'll start to see computer generated speech that is optimized for minimum bandwidth and maximum intelligibility rather than continue to use our clumsy, inefficient and highly variable biological speech mechanism called lungs, throat and mouth ;-) After all, we've largely dispensed with that personality in CW since most Hams have dumped their mechanical keys for keyers that compensate for most variations in fingers movements or even to a keyboard that eliminates any chance of human variability or inefficiency while pounding brass. Ron AC7AC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
On Mon, 21 Sep 2009 14:03:02 -0500, Grant Youngman wrote: Indeed. It may cut through better, but if you can't understand what's being said, what good does cutting through do. By cutting through I am specifically talking about speech intelligibility, and thanks to my background in pro audio and sound reinforcement, it is a topic I know quite a bit about. Sound systems that must provide speech intelligibility in difficult environments are carefully designed to limit the low frequency response. Three reasons. First, the lower octave bands make very little contribution to speech intelligibility. Second, the lower octave bands are most subject to the effects of reverberation. Third, the lower octave bands burn power that could be better used on the spectrum that does provide intelligibility. The only part of the above that doesn't apply directly to radio communications is reverberation. Note that no one is recommending excessive modulation or processing, which certainly does degrade intelligibility. The K3 can very easily be set up to limit the audio bandwidth, shape it to provide pre-emphasis for the bandwidth lost due to IF filters, and provide dynamics processing (compression). And it sounds VERY good when done properly. I'm coming at this from the perspective of an audio professional and a radio professional. I'm a Fellow of the Audio Engineering Society, passed my First Phone in 1959 and began working in broadcasting soon thereafter. For the last 20+ years, I've made my living designing sound systems for public spaces. 73, Jim Brown K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
Personally, I find that many modern SSB rigs do limit the high frequencies too much. For me, there's a big improvement in intelligibility between rolling off the highs quickly at 2.5 KHz and allowing a full 2.7 to 3.0 kHz through. 3.0 kHz was the standard communications upper frequency roll-off for many years going back through the AM days, and I find it's still preferable to me. A major difference today is that back then we simply rolled off the upper frequencies with the very simplest audio filtering - often just using bypass capacitors in the audio stages that tended to attenuate highs. The result was substantial audio energy being transmitted well above 3 kHz. Nowadays we have the filters to limit high frequencies much better. A clean square sided audio response that passes 150-200 Hz to 2800-3000 Hz (2.8 KHz bandwidth) with a notch between 750 and 1100 Hz and a response that rises at 3 - 6 dB per octave between 1000 and 3000 Hz is a thing of joy to hear. Such a response is very efficient use of bandwidth, is easy to understand but not harsh and almost natural sounding. Those who boost bass below 150-200 Hz do nothing but make their audio muddy - particularly if the bass boost is followed by any compression/clipping - and difficult to tune. I'd very much like to see the Elecraft equalizers modified to match 10 of the ISO 2/3 Octave standard (63, 100, 160, 250, 400, 630, 1000, 1600, 2500, 4000 Hz) frequencies. By having a band centered a 1000 Hz, it is possible to cut the interformat band (significantly reducing background noise in an area lacking any voice energy), to cut audio below even the most low pitched male voices (63 Hz), provide a smooth rising characteristic (1/1.6/2.5K) and sharply limit the high frequency (4K) components that cause adjacent channel interference without contributing to communication efficiency. In addition, control over the two groups (100/160/250/400 and 1600/2500) provide the ability to balance the high/low formats compensating for variations between strong/weak voices. 73, ... Joe, W4TV -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ron D'Eau Claire Sent: Monday, September 21, 2009 3:36 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware Jim, K9YC, wrote: Speakers with built-in amplifiers are notorious for RFI. I often tour the aisles at audio trade shows with a THF6A VHF/UHF talkie. In ten years, I've seen only one amplified loudspeaker that didn't pick up RF. It cost about $1,500 and was made in Europe. --- Ha! Bet the vendors loved your test ;-) I've tried a couple of different computer speakers as well as conventional bookshelf audio system speakers on my K3 and have found no need for using an auxiliary amplifier. The K3 has plenty of audio power to drive external speakers in almost any Hamshack. I'm currently using a pair of LabTec computer speakers that bypass the internal amplifier by simply disconnecting the wall wart that supplies the amplifier. Ignacy, you might try that and see if they work without powering the internal amp. As Jim observes, the ancient ones (and most hams today) don't limit their audio response out of ignorance or because they couldn't. They knew that bass takes lots of power and generally interferes with intelligibility, especially in us guys. Not only do low frequencies hog power as Jim noted, they are hardly modulated when we produce speech. Our mouths and lips mostly modulate the higher harmonics, typically above 300 Hz. The fundamental tone and low-order power-hogging harmonics produced by our vocal cords are just a drone with little variation other than starting and stopping. Personally, I find that many modern SSB rigs do limit the high frequencies too much. For me, there's a big improvement in intelligibility between rolling off the highs quickly at 2.5 KHz and allowing a full 2.7 to 3.0 kHz through. 3.0 kHz was the standard communications upper frequency roll-off for many years going back through the AM days, and I find it's still preferable to me. A major difference today is that back then we simply rolled off the upper frequencies with the very simplest audio filtering - often just using bypass capacitors in the audio stages that tended to attenuate highs. The result was substantial audio energy being transmitted well above 3 kHz. Nowadays we have the filters to limit high frequencies much better. I understand that there's good evidence that, when digging for a signal in the noise, a lower upper-frequency limit can provide better communications (provided the lows below 300 Hz or so are also attenuated). It's a matter of concentrating the finite amount of RF into the most effective part of the audio
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware [End of thread]
Guys - We've beat this topic to death. Let's end the thread, or take it off list, for the moment. 73, Eric WA6HHQ Elecraft List Moderator --- Jim Brown wrote: On Mon, 21 Sep 2009 14:03:02 -0500, Grant Youngman wrote: Indeed. It may cut through better, but if you can't understand what's being said, what good does cutting through do. By cutting through I am specifically talking about speech intelligibility, __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
On Sep 21, 2009, at 4:14 PM, Joe Subich, W4TV wrote: A clean square sided audio response that passes 150-200 Hz to 2800-3000 Hz (2.8 KHz bandwidth) with a notch between 750 and 1100 Hz and a response that rises at 3 - 6 dB per octave between 1000 and 3000 Hz is a thing of joy to hear. Such a response is very efficient use of bandwidth, is easy to understand but not harsh and almost natural sounding. Those who boost bass below 150-200 Hz do nothing but make their audio muddy - particularly if the bass boost is followed by any compression/clipping - and difficult to tune. It's natural if all of your friends are parrots. This is ridiculous. No one here is advocating 20Hz-20Khz as a regular option on the ham bands. (Well, you would if you really wanted to sound like YOU instead of a parrot, but that's another issue). There is nothing natural sounding about what you propose. Unless you have really bad hearing, or or just so used to thinking that nothing sounds better than a KWM-2 that anything else doesn't work. All of this efficiency stuff is smokescreen. You sound like a human being or you don't. You can understand (out of context) what the guy on the other end is saying or not. No one here is advocating using 20Hz to 20Khz transmit bandwidth in the context of good amateur practice. So why is there so much hard core insistence than we should have bad audio ALL of the time. Grant/NQ5T __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
I'm coming at this from the perspective of an audio professional and a radio professional. I'm a Fellow of the Audio Engineering Society, passed my First Phone in 1959 and began working in broadcasting soon thereafter. For the last 20+ years, I've made my living designing sound systems for public spaces WOW ! I am impressed,so you are the professional audio GURU in this group,we are honored to have you here.WOW!! AD4C The difference between genius and stupidity is that genius has its limits. -- Albert Einstein --- On Mon, 9/21/09, Jim Brown j...@audiosystemsgroup.com wrote: From: Jim Brown j...@audiosystemsgroup.com Subject: Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware To: Elecraft List elecraft@mailman.qth.net Date: Monday, September 21, 2009, 8:16 PM On Mon, 21 Sep 2009 14:03:02 -0500, Grant Youngman wrote: Indeed. It may cut through better, but if you can't understand what's being said, what good does cutting through do. By cutting through I am specifically talking about speech intelligibility, and thanks to my background in pro audio and sound reinforcement, it is a topic I know quite a bit about. Sound systems that must provide speech intelligibility in difficult environments are carefully designed to limit the low frequency response. Three reasons. First, the lower octave bands make very little contribution to speech intelligibility. Second, the lower octave bands are most subject to the effects of reverberation. Third, the lower octave bands burn power that could be better used on the spectrum that does provide intelligibility. The only part of the above that doesn't apply directly to radio communications is reverberation. Note that no one is recommending excessive modulation or processing, which certainly does degrade intelligibility. The K3 can very easily be set up to limit the audio bandwidth, shape it to provide pre-emphasis for the bandwidth lost due to IF filters, and provide dynamics processing (compression). And it sounds VERY good when done properly. I'm coming at this from the perspective of an audio professional and a radio professional. I'm a Fellow of the Audio Engineering Society, passed my First Phone in 1959 and began working in broadcasting soon thereafter. For the last 20+ years, I've made my living designing sound systems for public spaces. 73, Jim Brown K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
It's natural if all of your friends are parrots. It is far from a parrot and light years ahead of the muddy base rumble from the overly boosted, compressed and clipped 50-150 Hz that passes for audiophile product these days. This is ridiculous. No one here is advocating 20Hz-20Khz as a regular option on the ham bands. Even 20 Hz to 5 KHz is absurd on the amateur bands. More than 90% of all transceivers have IF filters that on their best days will pass 3 KHz ... most are less than that. To transmit a signal wider than 2.8 KHz (200 to 3200 or 150 to 3150 Hz) to 3.2 KHz (150 Hz to 3350 Hz) anywhere other than on 10 Meters for a local QSO is an absolute exercise in ego self-gratification and intentional QRM to other users of the band. Like K9YC, I have more than little professional familiarity with good audio. I spent my entire professional career in in the broadcast and recording industries and started out doing more than enough live recordings, talk shows, and live event audio to know what constitutes good and excellent audio for all purposes. More importantly, I know the difference between audio designed to go to a digital recording media and audio that needs to work through a band limited channel. So why is there so much hard core insistence than we should have bad audio ALL of the time. Nobody is insisting that we should have band audio, ever - but both Jim and I are saying that wide bandwidth and good audio are NOT the same. With the proper choice of passband, equalization, and judicious use of clipping/compression, one can have good audio in a reasonable bandwidth ... AM (5-7 KHz) or FM (12-15 KHz) broadcast audio bandwidths are not necessary or appropriate for amateur use at HF. -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Grant Youngman Sent: Monday, September 21, 2009 5:58 PM To: Elecraft List Subject: Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware On Sep 21, 2009, at 4:14 PM, Joe Subich, W4TV wrote: A clean square sided audio response that passes 150-200 Hz to 2800-3000 Hz (2.8 KHz bandwidth) with a notch between 750 and 1100 Hz and a response that rises at 3 - 6 dB per octave between 1000 and 3000 Hz is a thing of joy to hear. Such a response is very efficient use of bandwidth, is easy to understand but not harsh and almost natural sounding. Those who boost bass below 150-200 Hz do nothing but make their audio muddy - particularly if the bass boost is followed by any compression/clipping - and difficult to tune. It's natural if all of your friends are parrots. This is ridiculous. No one here is advocating 20Hz-20Khz as a regular option on the ham bands. (Well, you would if you really wanted to sound like YOU instead of a parrot, but that's another issue). There is nothing natural sounding about what you propose. Unless you have really bad hearing, or or just so used to thinking that nothing sounds better than a KWM-2 that anything else doesn't work. All of this efficiency stuff is smokescreen. You sound like a human being or you don't. You can understand (out of context) what the guy on the other end is saying or not. No one here is advocating using 20Hz to 20Khz transmit bandwidth in the context of good amateur practice. So why is there so much hard core insistence than we should have bad audio ALL of the time. Grant/NQ5T __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
Is this measured with high impedance probes? If I remember correctly, small caps limit low-frequency response of K3 especially with low impedance phones/speakers. Ignacy As a further experiment, I just added 3 dB to Rx bands 1-3 and the response is now essentially +/- 0dB between 20Hz and 3.5 kHz in SSB through the 6K filter and Fc = 1.35. You can lay the ruler flat on the response. http://216.229.20.37/images/K3-V333-EQ.jpg Paul, W9AC ___ -- View this message in context: http://n2.nabble.com/K3-Audio-Response-Version-3-33-Firmware-tp3673422p3680354.html Sent from the [K3] mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
Is this measured with high impedance probes? If I remember correctly, small caps limit low-frequency response of K3 especially with low impedance phones/speakers. Ignacy Correct, measured with a 2K-ohm load resistance at the sound card input. The purpose of the test was to measure only the response plots as a result of changes in DSP versions. To get a ruler-flat response down to 20 Hz with headphones may require a change in C9/C13 on the Main DSP Board, depending on the Z of your headphones at that frequency. I changed C9/C13 with 330uF units and this work well with any commercial headphones. If you refer to the K3's schematic, note that 8-ohm series build-out resistors are used and appear off-page. The addition of the build-out resistors has the effect of improving low-end response as the headphone Z decreases. As a practical matter, and assuming one is using newer headphones with a Z of at least 30 ohms at roughly 50 Hz, then Elecraft's revised Main DSP Board with 100uF caps at C9/C13 are completely sufficient. More info here: http://www.n1eu.com/K3/k3audiomod.htm W9AC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
Yes but unless the response remains that way when an 8 ohm speaker is there its not a very useful measurement. ~BTH On Sun, 2009-09-20 at 07:56 -0700, Ignacy wrote: Is this measured with high impedance probes? If I remember correctly, small caps limit low-frequency response of K3 especially with low impedance phones/speakers. Ignacy As a further experiment, I just added 3 dB to Rx bands 1-3 and the response is now essentially +/- 0dB between 20Hz and 3.5 kHz in SSB through the 6K filter and Fc = 1.35. You can lay the ruler flat on the response. http://216.229.20.37/images/K3-V333-EQ.jpg Paul, W9AC ___ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
Yes but unless the response remains that way when an 8 ohm speaker is there its not a very useful measurement. Since the speaker coupling capacitors are 470 uF, the roll off at 100 Hz with 8 Ohm speakers is 3 dB. That's completely acceptable for a communications receiver ... and probably less LF roll off than you will observe due to the speaker enclosure. 73, ... Joe, W4TV -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Brett Howard Sent: Sunday, September 20, 2009 7:42 PM To: Ignacy Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware Yes but unless the response remains that way when an 8 ohm speaker is there its not a very useful measurement. ~BTH On Sun, 2009-09-20 at 07:56 -0700, Ignacy wrote: Is this measured with high impedance probes? If I remember correctly, small caps limit low-frequency response of K3 especially with low impedance phones/speakers. Ignacy As a further experiment, I just added 3 dB to Rx bands 1-3 and the response is now essentially +/- 0dB between 20Hz and 3.5 kHz in SSB through the 6K filter and Fc = 1.35. You can lay the ruler flat on the response. http://216.229.20.37/images/K3-V333-EQ.jpg Paul, W9AC ___ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] [K3] K3 Audio Response - Version 3.33 Firmware
Yes but unless the response remains that way when an 8 ohm speaker is there its not a very useful measurement. The plots were meant to observe the radical changes in audio response across various firmware. These aren't subtle changes as one can see from the unloaded plots. With 330uF caps at C9/C13 and slight EQ boost (+ 3dB) on bands 1-3, I am confident that the response will appear as shown down to ~ 35 Hz with an 8-ohm load at the headphone output. The speaker output response plot should be comparable. I will be glad to make this measurement if there's any doubt. http://216.229.20.37/images/K3-V333-EQ.jpg Paul, W9AC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
