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#1
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Headset Impedance Parameters for a typical cellphone
Can anyone tell me the impedance specifications for a typical cellphone?
I'm interested in obtaining a "high-quality" headset from Sennheiser =3F one that's not specifically intended for use with cellphones. But I wonder if it will work reasonably well with a cellphone anyway. Their fact sheet on it . . . . . . . . . . . . . . . . . . http://www.sennheiserusa.com/newsite/pdfs/HMD280.pdf .. . . . . . . . . . . . . . . . . . . . . . . . . . . lists the following nominal impedance values: headphone: 300 Ohms microphone: 200 Ohms (dynamic transducer, supercardioid pickup pattern) I've already spoken with Sennheiser from whom I've received conflicting information. So, I thought I'd run this by you in hopes that someone might take a look and offer an informed opinion. Any help will be greatly appreciated. ----------------------------------- BACKGROUND: I'm about to embark on a new career as a trucker and a crucial piece of equipment will be a good mobile phone headset. Because of engine and road noise I'd like to get one with an over-the-ear headphone and a high-quality uni-directional boom mic. ----------------------------------- Thanks. -- _______ -CH ŻŻŻŻŻŻŻ |
#2
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
Crazy Horse wrote: Can anyone tell me the impedance specifications for a typical cellphone? I'm interested in obtaining a "high-quality" headset from Sennheiser =3F one that's not specifically intended for use with cellphones. But I wonder if it will work reasonably well with a cellphone anyway. Their fact sheet on it . . . . . . . . . . . . . . . . . . http://www.sennheiserusa.com/newsite/pdfs/HMD280.pdf . . . . . . . . . . . . . . . . . . . . . . . . . . . lists the following nominal impedance values: headphone: 300 Ohms microphone: 200 Ohms (dynamic transducer, supercardioid pickup pattern) I've already spoken with Sennheiser from whom I've received conflicting information. So, I thought I'd run this by you in hopes that someone might take a look and offer an informed opinion. Any help will be greatly appreciated. As long as your high quality headphones do not have an impedance *lower* than the phone expects (in which case you'd 'overload' the phone's electronics) , you'll be just fine. This is not an example of an 'impedance matching' issue at all, so don't waste time looking for exact values. Graham |
#3
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
Eeyore wrote:
Crazy Horse wrote: Can anyone tell me the impedance specifications for a typical cellphone? I'm interested in obtaining a "high-quality" headset from Sennheiser =3F one that's not specifically intended for use with cellphones. But I wonder if it will work reasonably well with a cellphone anyway. Their fact sheet on it . . . . . . . . . . . . . . . . . . http://www.sennheiserusa.com/newsite/pdfs/HMD280.pdf . . . . . . . . . . . . . . . . . . . . . . . . . . . lists the following nominal impedance values: headphone: 300 Ohms microphone: 200 Ohms (dynamic transducer, supercardioid pickup pattern) I've already spoken with Sennheiser from whom I've received conflicting information. So, I thought I'd run this by you in hopes that someone might take a look and offer an informed opinion. Any help will be greatly appreciated. As long as your high quality headphones do not have an impedance *lower* than the phone expects (in which case you'd 'overload' the phone's electronics) , you'll be just fine. This is not an example of an 'impedance matching' issue at all, so don't waste time looking for exact values. Graham I think the issue is more the microphone than the earpieces. All cellphones, TTBOMK, use condensors. The dynamic mic of the Sennies might not like having a bias voltage applied. If it doesn't 'mind' so much, the result might still not be satisfactory. jak |
#4
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
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#6
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
If the headphone impedance is 40 ohms or greater it should work.
The microphone is a condenser type, that requires a built in pre-amp. The phone should supply about 5 to 8 Volts, about 2 ma maximum for the microphone. When wiring in the microphone, make sure that the polarity is correct, and you do not cause any type of short, or you may need to have the cell phone serviced. -- JANA _____ "Crazy Horse" wrote in message k.net... Can anyone tell me the impedance specifications for a typical cellphone? I'm interested in obtaining a "high-quality" headset from Sennheiser =3F one that's not specifically intended for use with cellphones. But I wonder if it will work reasonably well with a cellphone anyway. Their fact sheet on it . . . . . . . . . . . . . . . . . . http://www.sennheiserusa.com/newsite/pdfs/HMD280.pdf .. . . . . . . . . . . . . . . . . . . . . . . . . . . lists the following nominal impedance values: headphone: 300 Ohms microphone: 200 Ohms (dynamic transducer, supercardioid pickup pattern) I've already spoken with Sennheiser from whom I've received conflicting information. So, I thought I'd run this by you in hopes that someone might take a look and offer an informed opinion. Any help will be greatly appreciated. ----------------------------------- BACKGROUND: I'm about to embark on a new career as a trucker and a crucial piece of equipment will be a good mobile phone headset. Because of engine and road noise I'd like to get one with an over-the-ear headphone and a high-quality uni-directional boom mic. ----------------------------------- Thanks. -- _______ -CH ŻŻŻŻŻŻŻ |
#7
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
"Crazy Horse" wrote ...
Can anyone tell me the impedance specifications for a typical cellphone? There probably isn't a "typical" cellphone design, nor a "typical" earphone impedance. I'm interested in obtaining a "high-quality" headset from Sennheiser one that's not specifically intended for use with cellphones. But I wonder if it will work reasonably well with a cellphone anyway. Their fact sheet on it . . . . . . . . . . . . . . . . . . http://www.sennheiserusa.com/newsite/pdfs/HMD280.pdf lists the following nominal impedance values: headphone: 300 Ohms The headphone has a reasonable expectation of working. Since cellphones run on such a low voltage (the internal battery), the receivers likely have a relatively low impedance to achieve adequate sensitivity. If there were to be any problem with a high-fidelity stereo headphone, it would be that the impedance was too HIGH so that the cell phone couldn't generate sufficient audio level to overcome your ambient noise. microphone: 200 Ohms (dynamic transducer, supercardioid pickup pattern) The microphone may be a different matter. Since likely ALL cell phones use electret condenser mics, there may be a problem with the DC power (required for electrets) being applied to the dynamic mic coil. There may also be a problem with the audio levels (sensitivity) of the dynamic mic vs. the electret that the cell phone is expecting. I've already spoken with Sennheiser from whom I've received conflicting information. They really aren't in any position to tell you whether it would work or not. Since they know nothing about whatever cell phone you have, they would just be guessing along with the rest of us. So, I thought I'd run this by you in hopes that someone might take a look and offer an informed opinion. The earphone/receivers would almost certainly work fine. IMHO, there is a significant chance that the microphone might not work as well as an electret condenser. But it is unlikely to cause any damage to the cell phone. Any help will be greatly appreciated. BACKGROUND: I'm about to embark on a new career as a trucker and a crucial piece of equipment will be a good mobile phone headset. Because of engine and road noise I'd like to get one with an over-the-ear headphone and a high-quality uni-directional boom mic. Note that over-the-ear headphones are dangerous to drive with and actually illegal in some jurisdictions. NOT recommended. If you really insist on noise-blocking over-the-ear headphones, I'd use a conventional cell-phone headset (made for your cell phone model) and put the receiver into a noise-blocking head set like a David Clark or equivalent. DC are the kind of ear protection they wear on the decks of aircraft carriers, etc. You might find a better fit with a headset made for aircraft use like this one on eBay # 280116629433 Noise blocking AND an electret microphone. |
#8
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
"Crazy Horse" wrote ...
Hmmmm... this resonates with what one of the Sennheiser guys said. I guess I was skeptical because I doubted that your typical cellphone headset uses a condensor mic. This doubt was based on my limited experience with condensor mics which have all included their own power source (i.e., a battery). Since I was pretty sure the cellphone headset mics I've seen have not inluded batteries, I wrongly surmised they weren't condensor mics. It is likely that ALL current cellphones use electret microphones. Both internally, and they likely expect electret mics with any external headsets, also. They feed the power on the same wire that they receive the audio from the mic, so external mics don't need any separate kind of power. Electret mics are smaller and cheaper than dynamic mics. These two parameters are VERY important to people who make cell phones by the millions. The guy at Sennheiser said that another Sennheiser (CC-550) headset http://www.sennheisercommunications....nsf/root/05361 has an "electret" mic. I think he said something about "polarized" leads that draw power from the device they're plugged into. Yes, thats how electret mics work. Anyway, I guess based on this information about the need for a condensor mic, I'll have to go with the CC-550, which is a shame in a way: compared to the HMD280, it looks like a toy! It IS a toy compared to the 280. But don't limit your research to high-end hi-fi headphones (280) and low-end consumer headsets (550). I did a search on eBay for david clark electret and turned up several promising hits for aircraft headsets running $100 that would beat the socks off the 550 for price and performance. |
#9
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
Crazy Horse wrote: says... I think the issue is more the microphone than the earpieces. All cellphones, TTBOMK, use condensors. The dynamic mic of the Sennies might not like having a bias voltage applied. If it doesn't 'mind' so much, the result might still not be satisfactory. Hmmmm... this resonates with what one of the Sennheiser guys said. I guess I was skeptical because I doubted that your typical cellphone headset uses a condensor mic. This doubt was based on my limited experience with condensor mics which have all included their own power source (i.e., a battery). There are 2 issues here about the power required for condenser mics. The actual element that picks up the sound in the mic (often called a capsule) requires a 'polarisation voltage' just to operate in the first place. More recently a different type of capsule based around electret materials which store electric charge in a way like magnets store magnetism have arrived on the scene and don't require this polarisation voltage. It's 'built in' if you like. Additional to that *all* capacitor mics require an amplifier stage immediately next to ther capsule. This requires power to operate too but usually at a much lower voltage than needed for those types that require polarisation. In the low-cost electret type this buffer amplifier is usually (invariably?) incorporated into the capsule assembly so it's not obvious. Since I was pretty sure the cellphone headset mics I've seen have not inluded batteries, I wrongly surmised they weren't condensor mics. In this case, the headset mic will doubtless be an electret and the power for the little amplifer next to/part of the capsule actually goes down the same wire as the audio signal. You'll see this as a DC voltage on the wire. The guy at Sennheiser said that another Sennheiser (CC-550) headset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . http://www.sennheisercommunications....sf/root/05361# . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . has an "electret" mic. I think he said something about "polarized" leads that draw power from the device they're plugged into. This is almost certainly the right type for you. Graham |
#10
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
In article ,
says... It is likely that ALL current cellphones use electret microphones. Both internally, and they likely expect electret mics with any external headsets, also. They feed the power on the same wire that they receive the audio from the mic, so external mics don't need any separate kind of power. : [snip] : In article , says... Note that over-the-ear headphones are dangerous to drive with and actually illegal in some jurisdictions. NOT recommended. : [snip] : Richard- You've given me a wealth of information to work with, and I thank you very much. I *had* looked at Sennheiser's aviation family, but they all seemed obscenely expensive ($500+!). But the other factor steering me away from them is the safety factor -- the Sennys had noise cancellation circuitry. My point being that I'm very sensitive to your cautionary words about the danger involved in blocking out ambient noise when driving. While I mentioned the HMD280 (dual-headphone), I was really leaning toward the HMD281 (single-headphone), for just this reason. I don't know if one can get single-headphone aviation headsets, but I suspect not. This gets me back to the Senny CC-550 (the toy)* http://www.sennheisercommunications....nsf/root/05361 or its single-headphone version (the CC-515). http://www.sennheisercommunications....f/root/5002150 I more than suspect these headphones -- being what I'd term "on-the- ear" vs. "over-the-ear" (e.g., HMD280, aviation headsets) -- would be *less* effective at ambient noise attenuation, and therefore safer when it comes to driving. So, what I'm trying to sort out now is whether the "dualies" might be ineffective *enough* such that they'd be sufficiently safe. In any event, I remain very grateful for your introducing me to the wider world of aviation headsets. I'm quite surprised they're so inexpensive. If I ever get into a "team driving" situation -- very unlikely barring I meet the "lady trucker girl-of-my-dreams" ;-) -- I will definitely look into these for my non-drive time in the truck. Once again, thanks a lot for all the info. I've saved both your posts to my "headsets" directory. All the best . . . _____________________________ * Also, there's something to be said for a low-profile cabling/jacks footprint when it comes to the confines of a truck cab -- not a deciding factor, but still worth consideration. -- _______ -CH ŻŻŻŻŻŻŻ |
#11
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
In article ,
says... There are 2 issues here about the power required for condenser mics. The actual element that picks up the sound in the mic (often called a capsule) requires a 'polarisation voltage' just to operate in the first place. More recently a different type of capsule based around electret materials which store electric charge in a way like magnets store magnetism have arrived on the scene and don't require this polarisation voltage. It's 'built in' if you like. Additional to that *all* capacitor mics require an amplifier stage immediately next to ther capsule. This requires power to operate too but usually at a much lower voltage than needed for those types that require polarisation. In the low-cost electret type this buffer amplifier is usually (invariably?) incorporated into the capsule assembly so it's not obvious. Crazy Horse wrote: Since I was pretty sure the cellphone headset mics I've seen have not inluded batteries, I wrongly surmised they weren't condensor mics. In this case, the headset mic will doubtless be an electret and the power for the little amplifer next to/part of the capsule actually goes down the same wire as the audio signal. You'll see this as a DC voltage on the wire. As Mr. Spock would say, "fascinating!" Thank you. Crazy Horse wrote: The guy at Sennheiser said that another Sennheiser (CC-550) headset http://www.sennheisercommunications....sf/root/05361# has an "electret" mic. I think he said something about "polarized" leads that draw power from the device they're plugged into. This is almost certainly the right type for you. Thanks for the feedback on the CC-550. I'm now leaning toward this one even more strongly, and largely out of safety considerations (as outlined in my reply to Robert). Thanks for all the info. Really, very helpful. -- _______ -CH ŻŻŻŻŻŻŻ |
#12
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
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#13
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
The impedance for most of the cell phone earphones and microphones
characteristics are an industry standard. Some of the different manufactures are using a different connector. Most of them are using a sub-sized tip-ring-sleeve type plug and jack arrangement. For these, you can buy most any telephone earphone device, and it should work. I have wired up my share of cell phones to different devices and self built devices with great success. If the impedance and sensitivity is respected, it will work. -- JANA _____ "Richard Crowley" wrote in message ... "Crazy Horse" wrote ... Can anyone tell me the impedance specifications for a typical cellphone? There probably isn't a "typical" cellphone design, nor a "typical" earphone impedance. I'm interested in obtaining a "high-quality" headset from Sennheiser one that's not specifically intended for use with cellphones. But I wonder if it will work reasonably well with a cellphone anyway. Their fact sheet on it . . . . . . . . . . . . . . . . . . http://www.sennheiserusa.com/newsite/pdfs/HMD280.pdf lists the following nominal impedance values: headphone: 300 Ohms The headphone has a reasonable expectation of working. Since cellphones run on such a low voltage (the internal battery), the receivers likely have a relatively low impedance to achieve adequate sensitivity. If there were to be any problem with a high-fidelity stereo headphone, it would be that the impedance was too HIGH so that the cell phone couldn't generate sufficient audio level to overcome your ambient noise. microphone: 200 Ohms (dynamic transducer, supercardioid pickup pattern) The microphone may be a different matter. Since likely ALL cell phones use electret condenser mics, there may be a problem with the DC power (required for electrets) being applied to the dynamic mic coil. There may also be a problem with the audio levels (sensitivity) of the dynamic mic vs. the electret that the cell phone is expecting. I've already spoken with Sennheiser from whom I've received conflicting information. They really aren't in any position to tell you whether it would work or not. Since they know nothing about whatever cell phone you have, they would just be guessing along with the rest of us. So, I thought I'd run this by you in hopes that someone might take a look and offer an informed opinion. The earphone/receivers would almost certainly work fine. IMHO, there is a significant chance that the microphone might not work as well as an electret condenser. But it is unlikely to cause any damage to the cell phone. Any help will be greatly appreciated. BACKGROUND: I'm about to embark on a new career as a trucker and a crucial piece of equipment will be a good mobile phone headset. Because of engine and road noise I'd like to get one with an over-the-ear headphone and a high-quality uni-directional boom mic. Note that over-the-ear headphones are dangerous to drive with and actually illegal in some jurisdictions. NOT recommended. If you really insist on noise-blocking over-the-ear headphones, I'd use a conventional cell-phone headset (made for your cell phone model) and put the receiver into a noise-blocking head set like a David Clark or equivalent. DC are the kind of ear protection they wear on the decks of aircraft carriers, etc. You might find a better fit with a headset made for aircraft use like this one on eBay # 280116629433 Noise blocking AND an electret microphone. |
#14
Posted to alt.cellular,alt.cellular-phone-tech,rec.audio.misc,rec.audio.tech
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Headset Impedance Parameters for a typical cellphone
There is a phenomenom in cellphone uplink audio on GSM systems called
"bumblebee." The problem is that the phone's transmitter modulates the mic capsule and/or the wire connecting it to the input preamp, resulting in a nasty 216 Hz (13E6/48 bits/second * 1 frame/ 1250 bits = 216.67 frames/second) tone with lots of harmonics. From this point of view, it would probably be better to get a mic capsule that has simultaneously high output power (so that the input preamp AGC doesn't amplify the bumblebee) and low impedance (so less RF is induced). --Randy "JANA" writes: The impedance for most of the cell phone earphones and microphones characteristics are an industry standard. Some of the different manufactures are using a different connector. Most of them are using a sub-sized tip-ring-sleeve type plug and jack arrangement. For these, you can buy most any telephone earphone device, and it should work. I have wired up my share of cell phones to different devices and self built devices with great success. If the impedance and sensitivity is respected, it will work. -- JANA _____ "Richard Crowley" wrote in message ... "Crazy Horse" wrote ... Can anyone tell me the impedance specifications for a typical cellphone? There probably isn't a "typical" cellphone design, nor a "typical" earphone impedance. I'm interested in obtaining a "high-quality" headset from Sennheiser one that's not specifically intended for use with cellphones. But I wonder if it will work reasonably well with a cellphone anyway. Their fact sheet on it . . . . . . . . . . . . . . . . . . http://www.sennheiserusa.com/newsite/pdfs/HMD280.pdf lists the following nominal impedance values: headphone: 300 Ohms The headphone has a reasonable expectation of working. Since cellphones run on such a low voltage (the internal battery), the receivers likely have a relatively low impedance to achieve adequate sensitivity. If there were to be any problem with a high-fidelity stereo headphone, it would be that the impedance was too HIGH so that the cell phone couldn't generate sufficient audio level to overcome your ambient noise. microphone: 200 Ohms (dynamic transducer, supercardioid pickup pattern) The microphone may be a different matter. Since likely ALL cell phones use electret condenser mics, there may be a problem with the DC power (required for electrets) being applied to the dynamic mic coil. There may also be a problem with the audio levels (sensitivity) of the dynamic mic vs. the electret that the cell phone is expecting. I've already spoken with Sennheiser from whom I've received conflicting information. They really aren't in any position to tell you whether it would work or not. Since they know nothing about whatever cell phone you have, they would just be guessing along with the rest of us. So, I thought I'd run this by you in hopes that someone might take a look and offer an informed opinion. The earphone/receivers would almost certainly work fine. IMHO, there is a significant chance that the microphone might not work as well as an electret condenser. But it is unlikely to cause any damage to the cell phone. Any help will be greatly appreciated. BACKGROUND: I'm about to embark on a new career as a trucker and a crucial piece of equipment will be a good mobile phone headset. Because of engine and road noise I'd like to get one with an over-the-ear headphone and a high-quality uni-directional boom mic. Note that over-the-ear headphones are dangerous to drive with and actually illegal in some jurisdictions. NOT recommended. If you really insist on noise-blocking over-the-ear headphones, I'd use a conventional cell-phone headset (made for your cell phone model) and put the receiver into a noise-blocking head set like a David Clark or equivalent. DC are the kind of ear protection they wear on the decks of aircraft carriers, etc. You might find a better fit with a headset made for aircraft use like this one on eBay # 280116629433 Noise blocking AND an electret microphone. -- % Randy Yates % "So now it's getting late, %% Fuquay-Varina, NC % and those who hesitate %%% 919-577-9882 % got no one..." %%%% % 'Waterfall', *Face The Music*, ELO http://home.earthlink.net/~yatescr |
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