Re: [Flexradio] Flex 5000A w/earbuds
There is indeed dc on the 5kA phones output. When I plug in a headphone I hear a loud pop (almost to the level it makes me think it'll be blown). I asked once why on earth this is needed, and got the answer that blocking this DC (by transformers or capacitors) would also block the lowest audio frequencies. I simply don't use the headphones output. BTW: I never heard that high end audio required our equipment to run DC through our voice coils. Rob, PA3CNT 2014-11-23 5:06 GMT+01:00 Bill Guyger via FlexRadio flexradio@flex-radio.biz: Forgot to add grab a voltmeter and check for DC Bill Sent from my iPhone On Nov 22, 2014, at 10:04 PM, Bill Guyger via FlexRadio flexradio@flex-radio.biz wrote: Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz -- Rob Keijzer PA3CNT ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds
A capacitor in-line of sufficient rating to handle the voltages to be encountered and with sufficient capacity to pass the lowest freqs of interest will turn off your ear heaters. Maybe you want to wire in a Summer-Winter switch to be able to select cool or warm operation as the seasons change. 73, Patrick NJ5G -Original Message- From: Bill Guyger via FlexRadio Sent: Saturday, November 22, 2014 10:04 PM To: Mike Sonn Cc: flexradio Subject: Re: [Flexradio] Flex 5000A w/earbuds Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds etc.
Yes, this is a very good solution! I had to do something like this but without the summer/winter switch when I decided to modify an ARC-5 BC453-B WWII receiver for SDR. It had occurred to me that it would be a good idea to explain to a local club how easy it was to convert the old radio to SDR. I proceeded to remove all of the original internal components from the BC-453 and then put a Flex1500 plus power supply plus cooling fan plus speaker plus audio amp in the box while carefully maintaining the original appearance of the old radio. I used an on line purchased small audio amp and computer speaker without giving thought to what I might be doing to the audio out of the Flex1500! Not at all smart and it resulted in an unplanned visit of my 1500 back to Austin! But that capacitor should be a word to the wise! 73 Lee K9WRU - Original Message - From: Patrick Greenlee patric...@windstream.net To: Bill Guyger bguy...@yahoo.com; Mike Sonn fatfend...@sbcglobal.net Cc: flexradio flexradio@flex-radio.biz Sent: Sunday, November 23, 2014 7:37 AM Subject: Re: [Flexradio] Flex 5000A w/earbuds A capacitor in-line of sufficient rating to handle the voltages to be encountered and with sufficient capacity to pass the lowest freqs of interest will turn off your ear heaters. Maybe you want to wire in a Summer-Winter switch to be able to select cool or warm operation as the seasons change. 73, Patrick NJ5G -Original Message- From: Bill Guyger via FlexRadio Sent: Saturday, November 22, 2014 10:04 PM To: Mike Sonn Cc: flexradio Subject: Re: [Flexradio] Flex 5000A w/earbuds Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds etc.
Yes, this is a very good solution! I had to do something like this but without the summer/winter switch when I decided to modify an ARC-5 BC453-B WWII receiver for SDR. It had occurred to me that it would be a good idea to explain to a local club how easy it was to convert the old radio to SDR. I proceeded to remove all of the original internal components from the BC-453 and then put a Flex1500 plus power supply plus cooling fan plus speaker plus audio amp in the box while carefully maintaining the original appearance of the old radio. I used an on line purchased small audio amp and computer speaker without giving thought to what I might be doing to the audio out of the Flex1500! Not at all smart and it resulted in an unplanned visit of my 1500 back to Austin! But that capacitor should be a word to the wise! 73 Lee K9WRU - Original Message - From: Patrick Greenlee patric...@windstream.net To: Bill Guyger bguy...@yahoo.com; Mike Sonn fatfend...@sbcglobal.net Cc: flexradio flexradio@flex-radio.biz Sent: Sunday, November 23, 2014 7:37 AM Subject: Re: [Flexradio] Flex 5000A w/earbuds A capacitor in-line of sufficient rating to handle the voltages to be encountered and with sufficient capacity to pass the lowest freqs of interest will turn off your ear heaters. Maybe you want to wire in a Summer-Winter switch to be able to select cool or warm operation as the seasons change. 73, Patrick NJ5G -Original Message- From: Bill Guyger via FlexRadio Sent: Saturday, November 22, 2014 10:04 PM To: Mike Sonn Cc: flexradio Subject: Re: [Flexradio] Flex 5000A w/earbuds Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds
I once had a tube type lab grade audio power amp with a switch on both channels to roll off freqs below 8 Hz for uses such as music so power would not be wasted in reproducing infra-sonic signals from such as footsteps vibrating a phono cartridge. Not sure what benefit audio down in the infra-sonic domain has for hams but if someone is doing something down there then please speak up as I'm sure lots of us would be interested. Crystal headsets would be immune to the DC. PatrickNJ5G -Original Message- From: Rob Keijzer Sent: Sunday, November 23, 2014 7:34 AM To: Bill Guyger Cc: Mike Sonn ; flexradio Subject: Re: [Flexradio] Flex 5000A w/earbuds There is indeed dc on the 5kA phones output. When I plug in a headphone I hear a loud pop (almost to the level it makes me think it'll be blown). I asked once why on earth this is needed, and got the answer that blocking this DC (by transformers or capacitors) would also block the lowest audio frequencies. I simply don't use the headphones output. BTW: I never heard that high end audio required our equipment to run DC through our voice coils. Rob, PA3CNT 2014-11-23 5:06 GMT+01:00 Bill Guyger via FlexRadio flexradio@flex-radio.biz: Forgot to add grab a voltmeter and check for DC Bill Sent from my iPhone On Nov 22, 2014, at 10:04 PM, Bill Guyger via FlexRadio flexradio@flex-radio.biz wrote: Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz -- Rob Keijzer PA3CNT ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds
A couple of separate answers: - Capacitors in series do roll off the lows, but if you pick a cap whose reactance at one octave below the lowest frequency that you wish to be flat is equal to the reactance (though you can probably get away with simply using the DC Resistance of the headphones for all practical purposes...) of the phones, the frequency response will be 3 dB down at that frequency but will be back to flat at one octave above the corner frequency. So if you assume a lowest desirable frequency of 300 Hz. for communications purpose pick a corner frequency of 150 Hz. - And back in the day (1920's - 1930's) the voice coil of the speaker was used for the filter choke, and if you look at old radio schematics, say in the ARRL Handbook, you will see the headphones in series with the B+ for the amplifier tube. But that went the way of the Dodo when transformers became more readily available. Most high end amplifiers either use a transformer, or in the case of transistor amps have complimentary output devices with B+ and B- supplies so (in theory) there is very little DC at the common point the speaker is connected to. If you do loose one side of the power supply the full tilt boogie voltage of the other supply will be applied to your speaker and you have a good chance of blowing the voice coil.I have literally seen a speaker cabinet catch fire and burn because the amp went into DC. High quality amps have protection circuits to prevent that, but the Certain Vagrant (Cerwin Vega) amp that caused the fire did not because Vega was really cheaply designed. Bill AD5OL From: Rob Keijzer pa3...@amsat.org To: Bill Guyger bguy...@yahoo.com Cc: flexradio flexradio@flex-radio.biz; Mike Sonn fatfend...@sbcglobal.net Sent: Sunday, November 23, 2014 7:34 AM Subject: Re: [Flexradio] Flex 5000A w/earbuds There is indeed dc on the 5kA phones output. When I plug in a headphone I hear a loud pop (almost to the level it makes me think it'll be blown). I asked once why on earth this is needed, and got the answer that blocking this DC (by transformers or capacitors) would also block the lowest audio frequencies. I simply don't use the headphones output. BTW: I never heard that high end audio required our equipment to run DC through our voice coils. Rob, PA3CNT 2014-11-23 5:06 GMT+01:00 Bill Guyger via FlexRadio flexradio@flex-radio.biz: Forgot to add grab a voltmeter and check for DC Bill Sent from my iPhone On Nov 22, 2014, at 10:04 PM, Bill Guyger via FlexRadio flexradio@flex-radio.biz wrote: Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz -- Rob Keijzer PA3CNT ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds
On 11/23/2014 08:31 AM, Bill Guyger via FlexRadio wrote: A couple of separate answers: - Capacitors in series do roll off the lows, but if you pick a cap whose reactance at one octave below the lowest frequency that you wish to be flat is equal to the reactance (though you can probably get away with simply using the DC Resistance of the headphones for all practical purposes...) of the phones, the frequency response will be 3 dB down at that frequency but will be back to flat at one octave above the corner frequency. So if you assume a lowest desirable frequency of 300 Hz. for communications purpose pick a corner frequency of 150 Hz. - And back in the day (1920's - 1930's) the voice coil of the speaker was used for the filter choke, and if you look at old radio schematics, say in the ARRL Handbook, you will see the headphones in series with the B+ for the amplifier tube. But that went the way of the Dodo when transformers became more readily available. Most high end amplifiers either use a transformer, or in the case of transistor amps have complimentary output devices with B+ and B- supplies so (in theory) there is very little DC at the common point the speaker is connected to. If you do loose one side of the power supply the full tilt boogie voltage of the other supply will be applied to your speaker and you have a good chance of blowing the voice coil.I have literally seen a speaker cabinet catch fire and burn because the amp went into DC. High quality amps have protection circuits to prevent that, but the Certain Vagrant (Cerwin Vega) amp that caused the fire did not because Vega was really cheaply designed. Bill AD5OL From: Rob Keijzer pa3...@amsat.org To: Bill Guyger bguy...@yahoo.com Cc: flexradio flexradio@flex-radio.biz; Mike Sonn fatfend...@sbcglobal.net Sent: Sunday, November 23, 2014 7:34 AM Subject: Re: [Flexradio] Flex 5000A w/earbuds There is indeed dc on the 5kA phones output. When I plug in a headphone I hear a loud pop (almost to the level it makes me think it'll be blown). I asked once why on earth this is needed, and got the answer that blocking this DC (by transformers or capacitors) would also block the lowest audio frequencies. I simply don't use the headphones output. BTW: I never heard that high end audio required our equipment to run DC through our voice coils. Rob, PA3CNT 2014-11-23 5:06 GMT+01:00 Bill Guyger via FlexRadio flexradio@flex-radio.biz: Forgot to add grab a voltmeter and check for DC Bill Sent from my iPhone On Nov 22, 2014, at 10:04 PM, Bill Guyger via FlexRadio flexradio@flex-radio.biz wrote: Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz In the old days the loudspeaker used a field coil instead of a permanent magnet. The B+ supply had a capacitor input, then the field coil, then the rest of the radio. A hum bucking winding was sometimes used. I don't know of any radios that had B+ on the headphone terminals. A bit shocking I'd think. -- Chuck Forsberg WA7KGX c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds
Very dangerous, but that's the they built radios back then. Everything was open, you could grab a hand full of electrons real easily ! Bill Sent from my iPhone On Nov 23, 2014, at 10:45 AM, Chuck Forsberg WA7KGX c...@omen.com wrote: On 11/23/2014 08:31 AM, Bill Guyger via FlexRadio wrote: A couple of separate answers: - Capacitors in series do roll off the lows, but if you pick a cap whose reactance at one octave below the lowest frequency that you wish to be flat is equal to the reactance (though you can probably get away with simply using the DC Resistance of the headphones for all practical purposes...) of the phones, the frequency response will be 3 dB down at that frequency but will be back to flat at one octave above the corner frequency. So if you assume a lowest desirable frequency of 300 Hz. for communications purpose pick a corner frequency of 150 Hz. - And back in the day (1920's - 1930's) the voice coil of the speaker was used for the filter choke, and if you look at old radio schematics, say in the ARRL Handbook, you will see the headphones in series with the B+ for the amplifier tube. But that went the way of the Dodo when transformers became more readily available. Most high end amplifiers either use a transformer, or in the case of transistor amps have complimentary output devices with B+ and B- supplies so (in theory) there is very little DC at the common point the speaker is connected to. If you do loose one side of the power supply the full tilt boogie voltage of the other supply will be applied to your speaker and you have a good chance of blowing the voice coil.I have literally seen a speaker cabinet catch fire and burn because the amp went into DC. High quality amps have protection circuits to prevent that, but the Certain Vagrant (Cerwin Vega) amp that caused the fire did not because Vega was really cheaply designed. Bill AD5OL From: Rob Keijzer pa3...@amsat.org To: Bill Guyger bguy...@yahoo.com Cc: flexradio flexradio@flex-radio.biz; Mike Sonn fatfend...@sbcglobal.net Sent: Sunday, November 23, 2014 7:34 AM Subject: Re: [Flexradio] Flex 5000A w/earbuds There is indeed dc on the 5kA phones output. When I plug in a headphone I hear a loud pop (almost to the level it makes me think it'll be blown). I asked once why on earth this is needed, and got the answer that blocking this DC (by transformers or capacitors) would also block the lowest audio frequencies. I simply don't use the headphones output. BTW: I never heard that high end audio required our equipment to run DC through our voice coils. Rob, PA3CNT 2014-11-23 5:06 GMT+01:00 Bill Guyger via FlexRadio flexradio@flex-radio.biz: Forgot to add grab a voltmeter and check for DC Bill Sent from my iPhone On Nov 22, 2014, at 10:04 PM, Bill Guyger via FlexRadio flexradio@flex-radio.biz wrote: Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz In the old days the loudspeaker used a field coil instead of a permanent magnet. The B+ supply had a capacitor input, then the field coil, then the rest of the radio. A hum bucking winding was sometimes used. I don't know of any radios that had B+ on the headphone terminals. A bit shocking I'd think. -- Chuck Forsberg WA7KGX c...@omen.com www.omen.com Developer of Industrial ZMODEM(Tm) for Embedded Applications Omen Technology Inc The High Reliability Software 10255 NW Old Cornelius Pass Portland OR 97231 503-614-0430 ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex
Re: [Flexradio] Flex 5000A w/earbuds
On 11/23/2014 9:19 AM, Patrick Greenlee wrote: I once had a tube type lab grade audio power amp with a switch on both channels to roll off freqs below 8 Hz for uses such as music so power would not be wasted in reproducing infra-sonic signals from such as footsteps vibrating a phono cartridge. Not sure what benefit audio down in the infra-sonic domain has for hams but if someone is doing something down there then please speak up as I'm sure lots of us would be interested. [...] For audio _inputs_ that might be used to transmit highly-processed waveforms, I can see great advantages to DC coupling. Orban recommends flat frequency response down to a least 0.16 Hz (not a typo!) for AM broadcast transmitter audio stages in which the actual audio frequencies are no lower than 30 Hz. Without such extended response, processed audio waveforms (which are sometimes flat-topped like square waves) would be unacceptably distorted. Perhaps some other modes have similarly stringent requirements. But I don't see why a headphone output needs to be DC-coupled. A capacitor-coupled output that gives flat response down to 30 Hz should be fine even for audiophiles listening to ESSB operators or organ concerts on broadcast stations. 73, Kevin, WB4AIO. ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds
I think I found my answer and you guys were right... Quote: The headphone circuitry in the FLEX-5000 uses Output Coupled Load (OCL) amplifier with a 2.5V bias. Headphone requirements for the Flex 5000 That sucks, love my earbuds, they're so much better due to weight, but don't really want to mess around adding a capacitor. Thanks,Mike KF9AF On Sunday, November 23, 2014 10:31 AM, Bill Guyger bguy...@yahoo.com wrote: A couple of separate answers: - Capacitors in series do roll off the lows, but if you pick a cap whose reactance at one octave below the lowest frequency that you wish to be flat is equal to the reactance (though you can probably get away with simply using the DC Resistance of the headphones for all practical purposes...) of the phones, the frequency response will be 3 dB down at that frequency but will be back to flat at one octave above the corner frequency. So if you assume a lowest desirable frequency of 300 Hz. for communications purpose pick a corner frequency of 150 Hz. - And back in the day (1920's - 1930's) the voice coil of the speaker was used for the filter choke, and if you look at old radio schematics, say in the ARRL Handbook, you will see the headphones in series with the B+ for the amplifier tube. But that went the way of the Dodo when transformers became more readily available. Most high end amplifiers either use a transformer, or in the case of transistor amps have complimentary output devices with B+ and B- supplies so (in theory) there is very little DC at the common point the speaker is connected to. If you do loose one side of the power supply the full tilt boogie voltage of the other supply will be applied to your speaker and you have a good chance of blowing the voice coil. I have literally seen a speaker cabinet catch fire and burn because the amp went into DC. High quality amps have protection circuits to prevent that, but the Certain Vagrant (Cerwin Vega) amp that caused the fire did not because Vega was really cheaply designed. Bill AD5OL From: Rob Keijzer pa3...@amsat.org To: Bill Guyger bguy...@yahoo.com Cc: flexradio flexradio@flex-radio.biz; Mike Sonn fatfend...@sbcglobal.net Sent: Sunday, November 23, 2014 7:34 AM Subject: Re: [Flexradio] Flex 5000A w/earbuds There is indeed dc on the 5kA phones output. When I plug in a headphone I hear a loud pop (almost to the level it makes me think it'll be blown). I asked once why on earth this is needed, and got the answer that blocking this DC (by transformers or capacitors) would also block the lowest audio frequencies. I simply don't use the headphones output. BTW: I never heard that high end audio required our equipment to run DC through our voice coils. Rob, PA3CNT 2014-11-23 5:06 GMT+01:00 Bill Guyger via FlexRadio flexradio@flex-radio.biz: Forgot to add grab a voltmeter and check for DC Bill Sent from my iPhone On Nov 22, 2014, at 10:04 PM, Bill Guyger via FlexRadio flexradio@flex-radio.biz wrote: Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz -- Rob Keijzer PA3CNT ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds
The 5000a uses an LM4911 in an OCL configuration. See the device data sheet. The barrel of the headphone jack IS NOT GROUNDED. Rather it is biased to half the 4911's supply voltage, as are the left and right headphone outputs. The barrel and the stereo headphone outputs all show 2.41 volts on my Chinese DMM. The results are undefined if you short any part of the headphone connector to ground. I listened very carefully with my headphones while plugging them in to my 5000a and heard NO clicks or pops. If you measure a DC voltage between the headphone wires, something is wrong. On 11/23/2014 07:52 PM, Mike Sonn wrote: I think I found my answer and you guys were right... Quote: The headphone circuitry in the FLEX-5000 uses Output Coupled Load (OCL) amplifier with a 2.5V bias. Headphone requirements for the Flex 5000 That sucks, love my earbuds, they're so much better due to weight, but don't really want to mess around adding a capacitor. Thanks,Mike KF9AF On Sunday, November 23, 2014 10:31 AM, Bill Guyger bguy...@yahoo.com wrote: A couple of separate answers: - Capacitors in series do roll off the lows, but if you pick a cap whose reactance at one octave below the lowest frequency that you wish to be flat is equal to the reactance (though you can probably get away with simply using the DC Resistance of the headphones for all practical purposes...) of the phones, the frequency response will be 3 dB down at that frequency but will be back to flat at one octave above the corner frequency. So if you assume a lowest desirable frequency of 300 Hz. for communications purpose pick a corner frequency of 150 Hz. - And back in the day (1920's - 1930's) the voice coil of the speaker was used for the filter choke, and if you look at old radio schematics, say in the ARRL Handbook, you will see the headphones in series with the B+ for the amplifier tube. But that went the way of the Dodo when transformers became more readily available. Most high end amplifiers either use a transformer, or in the case of transistor amps have complimentary output devices with B+ and B- supplies so (in theory) there is very little DC at the common point the speaker is connected to. If you do loose one side of the power supply the full tilt boogie voltage of the other supply will be applied to your speaker and you have a good chance of blowing the voice coil. I have literally seen a speaker cabinet catch fire and burn because the amp went into DC. High quality amps have protection circuits to prevent that, but the Certain Vagrant (Cerwin Vega) amp that caused the fire did not because Vega was really cheaply designed. Bill AD5OL From: Rob Keijzer pa3...@amsat.org To: Bill Guyger bguy...@yahoo.com Cc: flexradio flexradio@flex-radio.biz; Mike Sonn fatfend...@sbcglobal.net Sent: Sunday, November 23, 2014 7:34 AM Subject: Re: [Flexradio] Flex 5000A w/earbuds There is indeed dc on the 5kA phones output. When I plug in a headphone I hear a loud pop (almost to the level it makes me think it'll be blown). I asked once why on earth this is needed, and got the answer that blocking this DC (by transformers or capacitors) would also block the lowest audio frequencies. I simply don't use the headphones output. BTW: I never heard that high end audio required our equipment to run DC through our voice coils. Rob, PA3CNT 2014-11-23 5:06 GMT+01:00 Bill Guyger via FlexRadio flexradio@flex-radio.biz: Forgot to add grab a voltmeter and check for DC Bill Sent from my iPhone On Nov 22, 2014, at 10:04 PM, Bill Guyger via FlexRadio flexradio@flex-radio.biz wrote: Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz -- Chuck Forsberg WA7KGX
[Flexradio] Flex 5000A w/earbuds
Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds
Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
Re: [Flexradio] Flex 5000A w/earbuds
Forgot to add grab a voltmeter and check for DC Bill Sent from my iPhone On Nov 22, 2014, at 10:04 PM, Bill Guyger via FlexRadio flexradio@flex-radio.biz wrote: Heating in headphones and speakers is usually caused by D.C. coming out of the amp. I underline usually maybe something I'm not considering though. Bill AD5OL Sent from my iPhone On Nov 22, 2014, at 8:27 PM, Mike Sonn fatfend...@sbcglobal.net wrote: Anyone else use earbuds? I've used a set for years with my Flex 3000. I now have upgraded to a FLEX 5K and when I stuck my earbuds in for the first time, they were very warm. I thought I had them leaning against something warm in the shack, but after sitting on the desk for 10 minutes, they are still warm. My ear canals won't get cold, but clearly, there's something strange going on here. Any ideas? ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz ___ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz To opt out of the Reflector: http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz
