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#1
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue 12H
I've got two of these mics, but their usefulness seems limited.
For one, if you try to improperly drive a low-Z mic pre, you still get a signal, but a very small one, as only pin 3 is driven, with pin 2 left open, and pin 1 grounded. And then the only XLR to 1/4" unbalanced cable that I had lying around, was actually wired with pins 1 and 3 grounded, and pin 2 as the signal wire. WTF??? I would guess there isn't a wiring standard going from unbalanced XLR to unbalanced 1/4"? Who decided it was a good idea to use an XLR connection for an unbalanced output? Where one pin is not used at all? I assume this was done just because of the popularity of the XLR, and for the purpose of confusing the public? Can I convert these mics to Low-Z, by removing the output transformers, and driving pins 2 and 3 directly from the capsules? That would seem to make them much more useful.... |
#2
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/26/2016 8:16 PM, Paul wrote:
I've got two of these mics, but their usefulness seems limited. For one, if you try to improperly drive a low-Z mic pre, you still get a signal, but a very small one, as only pin 3 is driven, with pin 2 left open, and pin 1 grounded. Well, that's not the best situation, but it's still workable if you wire it correctly. And then the only XLR to 1/4" unbalanced cable that I had lying around, was actually wired with pins 1 and 3 grounded, and pin 2 as the signal wire. WTF??? It's a historical thing. Pin 3 used to be hot with respect to Pin 2, but then about 20 years ago, the industry pretty much standardized with pin 2 hot with respect to Pin 3. You have an old mic with a new cable. But if you're connecting it to a low impedance mic preamp, you need a signal between pins 2 and 3, and if pin 2 is open on the mic, then you won't get the voltage where you need it until you ground Pin 2 on the mic. I would guess there isn't a wiring standard going from unbalanced XLR to unbalanced 1/4"? No, there isn't, because that's not a very common thing to do. Usually an unbalanced mic has a 1/4" phone plug at the end of its cable, and an adapter with a female 1/4" jack on one end and a male XLR plug on the other end is wired so that the tip goes to pin 2 and pins 1 and 3 are connected to the shield (ground). Who decided it was a good idea to use an XLR connection for an unbalanced output? The bean counters. If they used the same parts on both the high and low impedance version of what's otherwise the same mic, they can save some money. They expected you to use the cable that they probably originally provided with the mic, and they expected you to plug the 1/4" plug on the end of that cable into a high impedance unbalanced input. I assume this was done just because of the popularity of the XLR, and for the purpose of confusing the public? Nobody's confused but you. Can I convert these mics to Low-Z, by removing the output transformers, and driving pins 2 and 3 directly from the capsules? That would seem to make them much more useful.... Try the simple solution first. Modify an XLR cable so that you get signal across the inputs of your mic preamp and see what that gets you. Even though there will be some voltage drop across the high source impedance, the output voltage of the mic for a given SPL is 16 dB higher for the high impedance version than for the low impedance version, so you'll probably have enough level. What you're giving up is the common mode rejection offered by a balanced connection, and some high frequency loss if you use a very long cable. I don't know for sure, but I'd guess that the low impedance version has a transformer as well, just a different transformer. Or maybe it's the same transformer and you can convert it to low impedance by using a different tap. E-V mics did this - they brought out both the low and high impedance taps to a 4-pin connector (not an XLR) and you just wired up the mating connector for low or high impedance as you needed it. I couldn't find a detailed document for the mic on line, so I guess maybe they don't want you to mess with it. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#3
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/26/2016 7:47 PM, Mike Rivers wrote:
On 3/26/2016 8:16 PM, Paul wrote: I've got two of these mics, but their usefulness seems limited. For one, if you try to improperly drive a low-Z mic pre, you still get a signal, but a very small one, as only pin 3 is driven, with pin 2 left open, and pin 1 grounded. Well, that's not the best situation, but it's still workable if you wire it correctly. And then the only XLR to 1/4" unbalanced cable that I had lying around, was actually wired with pins 1 and 3 grounded, and pin 2 as the signal wire. WTF??? It's a historical thing. Pin 3 used to be hot with respect to Pin 2, but then about 20 years ago, the industry pretty much standardized with pin 2 hot with respect to Pin 3. You have an old mic with a new cable. But if you're connecting it to a low impedance mic preamp, you need a signal between pins 2 and 3, and if pin 2 is open on the mic, then you won't get the voltage where you need it until you ground Pin 2 on the mic. I would guess there isn't a wiring standard going from unbalanced XLR to unbalanced 1/4"? No, there isn't, because that's not a very common thing to do. Usually an unbalanced mic has a 1/4" phone plug at the end of its cable, and an adapter with a female 1/4" jack on one end and a male XLR plug on the other end is wired so that the tip goes to pin 2 and pins 1 and 3 are connected to the shield (ground). Who decided it was a good idea to use an XLR connection for an unbalanced output? The bean counters. If they used the same parts on both the high and low impedance version of what's otherwise the same mic, they can save some money. They expected you to use the cable that they probably originally provided with the mic, and they expected you to plug the 1/4" plug on the end of that cable into a high impedance unbalanced input. I assume this was done just because of the popularity of the XLR, and for the purpose of confusing the public? Nobody's confused but you. Can I convert these mics to Low-Z, by removing the output transformers, and driving pins 2 and 3 directly from the capsules? That would seem to make them much more useful.... Try the simple solution first. Modify an XLR cable so that you get signal across the inputs of your mic preamp and see what that gets you. Even though there will be some voltage drop across the high source impedance, the output voltage of the mic for a given SPL is 16 dB higher for the high impedance version than for the low impedance version, so you'll probably have enough level. What you're giving up is the common mode rejection offered by a balanced connection, and some high frequency loss if you use a very long cable. I don't know for sure, but I'd guess that the low impedance version has a transformer as well, just a different transformer. Or maybe it's the same transformer and you can convert it to low impedance by using a different tap. E-V mics did this - they brought out both the low and high impedance taps to a 4-pin connector (not an XLR) and you just wired up the mating connector for low or high impedance as you needed it. I couldn't find a detailed document for the mic on line, so I guess maybe they don't want you to mess with it. Well, indeed, they had the Hi-Z AND Lo-Z versions of the same mic: http://cdn.shure.com/user_guide/uplo...logue12_ug.pdf Not sure if the transformer has another tap I can use. "Try the simple solution first. Modify an XLR cable so that you get signal across the inputs of your mic preamp and see what that gets you." I tried shorting pin 2 to ground on one of these mics (is this the same thing you suggested to do with the modified XLR cable? shorting pin 2 to ground?). This makes one side of the pre-amp balanced transformer go to ground, instead of open. It makes the signal stronger, but not by a huge amount. Certainly not the same signal level as my Lo-Z dynamics, obviously. I guess it might be good enough...maybe I'll take one of the transformers out, and see if it has another tap..... Thanks for the feedback.... |
#4
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/26/2016 11:32 PM, Paul wrote:
Well, indeed, they had the Hi-Z AND Lo-Z versions of the same mic: http://cdn.shure.com/user_guide/uplo...logue12_ug.pdf Yes, I found that instruction sheet. But what it didn't show was the wiring of the connector, or of a transformer, but I guess you've taken the mic apart and found one. I tried shorting pin 2 to ground on one of these mics (is this the same thing you suggested to do with the modified XLR cable? What you want to do is connect pins 1 and 2 together. Pin 1 may or may not be connected to the cable shield and/or the case of the mic. This makes one side of the pre-amp balanced transformer go to ground, instead of open. Correct. You no longer have a balanced connection, but at least you have signal continuity through the cable. With only one wire actually connected to one of the signal pins on the mic preamp, the circuit is completed only by capacitance, not by a DC path. That's why you get some signal, but weak, and lacking in low frequencies. It makes the signal stronger, but not by a huge amount. Certainly not the same signal level as my Lo-Z dynamics, obviously. Right. According to the spec sheet, the source impedance of the mic is about 47 k Ohms. Assuming that your mic has an input impedance of about 2.5 k Ohms, about 47/50ths of the capsule voltage will be dropped across the the mic's internal impedance, that represents an attenuation of about 26 dB. Since the output level of the Hi-Z version is specified as being 16 dB higher than that of the Low-Z version, that means that you'll get about 10 dB less signal for the same source level (or need 10 dB more gain to get back to the same level as with the low impedance version of the mic. Use it on a drum or an instrument amplifier. Don't use it on a dulcimer or the crickets at dawn. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#5
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/27/2016 4:50 AM, Mike Rivers wrote:
On 3/26/2016 11:32 PM, Paul wrote: Well, indeed, they had the Hi-Z AND Lo-Z versions of the same mic: http://cdn.shure.com/user_guide/uplo...logue12_ug.pdf Yes, I found that instruction sheet. But what it didn't show was the wiring of the connector, or of a transformer, but I guess you've taken the mic apart and found one. I tried shorting pin 2 to ground on one of these mics (is this the same thing you suggested to do with the modified XLR cable? What you want to do is connect pins 1 and 2 together. Pin 1 may or may not be connected to the cable shield and/or the case of the mic. Ok, yes, pin 1 is grounded to the case, so your suggested cable mod would do the same. This makes one side of the pre-amp balanced transformer go to ground, instead of open. Correct. You no longer have a balanced connection, but at least you have signal continuity through the cable. With only one wire actually connected to one of the signal pins on the mic preamp, the circuit is completed only by capacitance, not by a DC path. That's why you get some signal, but weak, and lacking in low frequencies. It makes the signal stronger, but not by a huge amount. Certainly not the same signal level as my Lo-Z dynamics, obviously. Right. According to the spec sheet, the source impedance of the mic is about 47 k Ohms. Assuming that your mic has an input impedance of about 2.5 k Ohms, about 47/50ths of the capsule voltage will be dropped across the the mic's internal impedance, that represents an attenuation of about 26 dB. Since the output level of the Hi-Z version is specified as being 16 dB higher than that of the Low-Z version, that means that you'll get about 10 dB less signal for the same source level (or need 10 dB more gain to get back to the same level as with the low impedance version of the mic. Yep. For any newbies reading: 20*log(2.5/49.5) = about -25.9333dB Use it on a drum or an instrument amplifier. Don't use it on a dulcimer or the crickets at dawn. Ok, great. Thanks for the engineering review and insight...how many years have you been in pro audio? I'll mod both mics to have pin2=Hot, and pin3=grounded, to match the cable I have. Thanks again.... |
#6
Posted to rec.audio.pro
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue 12H
In article , Paul wrote:
I've got two of these mics, but their usefulness seems limited. For one, if you try to improperly drive a low-Z mic pre, you still get a signal, but a very small one, as only pin 3 is driven, with pin 2 left open, and pin 1 grounded. This is a communications thing. They often use pin 3 hot, with pin 2 used for a push-to-talk switch. And then the only XLR to 1/4" unbalanced cable that I had lying around, was actually wired with pins 1 and 3 grounded, and pin 2 as the signal wire. WTF??? I would guess there isn't a wiring standard going from unbalanced XLR to unbalanced 1/4"? For many years there wasn't any standard for balanced XLR, even. The Pin 3 vs. Pin 2 people argued for years. Well, some of them are still arguing. Can I convert these mics to Low-Z, by removing the output transformers, and driving pins 2 and 3 directly from the capsules? That would seem to make them much more useful.... Likely. There is a low-Z version of these microphones called the Prologue 12L. Get the maintenance sheet from Shure. It likely has the same element; if it's wired without any transformer, then try it. It's possible that instead it has a different transformer in the box, though. These were popular paging microphones for supermarkets and busses; they are not going to be hi-fi. Might be interesting on a guitar amp though. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#7
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/27/2016 9:25 AM, Paul wrote:
Ok, great. Thanks for the engineering review and insight...how many years have you been in pro audio? I'll mod both mics to have pin2=Hot, and pin3=grounded, to match the cable I have. Oh, about 60 years, I guess. Hard to remember just when I started, or when I became "pro." -- For a good time, visit http://mikeriversaudio.wordpress.com |
#8
Posted to rec.audio.pro
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/27/2016 6:26 AM, Scott Dorsey wrote:
In article , Paul wrote: I've got two of these mics, but their usefulness seems limited. For one, if you try to improperly drive a low-Z mic pre, you still get a signal, but a very small one, as only pin 3 is driven, with pin 2 left open, and pin 1 grounded. This is a communications thing. They often use pin 3 hot, with pin 2 used for a push-to-talk switch. And then the only XLR to 1/4" unbalanced cable that I had lying around, was actually wired with pins 1 and 3 grounded, and pin 2 as the signal wire. WTF??? I would guess there isn't a wiring standard going from unbalanced XLR to unbalanced 1/4"? For many years there wasn't any standard for balanced XLR, even. The Pin 3 vs. Pin 2 people argued for years. Well, some of them are still arguing. Can I convert these mics to Low-Z, by removing the output transformers, and driving pins 2 and 3 directly from the capsules? That would seem to make them much more useful.... Likely. There is a low-Z version of these microphones called the Prologue 12L. Get the maintenance sheet from Shure. It likely has the same element; if it's wired without any transformer, then try it. It's possible that instead it has a different transformer in the box, though. These were popular paging microphones for supermarkets and busses; they are not going to be hi-fi. Might be interesting on a guitar amp though. --scott Mike suggested drums, due to the low signal level when using with low-Z pre-amps. So maybe these would be good as tom-tom mics, or for the floor tom? |
#9
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/27/2016 4:25 PM, Paul wrote:
Mike suggested drums, due to the low signal level when using with low-Z pre-amps. So maybe these would be good as tom-tom mics, or for the floor tom? If you have drums to record, give 'em a try. At least you won't have an overloading problem, unless the mics themselves crap out due to a higher SPL than speech, which seems to be what they're mostly designed for. But other than cymbals, the high frequency droop that you might due to a long cable shouldn't be a problem. It would be about around a 6 dB drop at around 5 kHz for a 25 foot cable here, not a big deal for toms. Just this week I watched a session with Sylvia Massy producing, and she used all sorts of odd mics on the drums, including a room mic consisting of an SM-57 taped into one end of a garden hose draped around the drum kit on the floor. And some conventional mics and mic positions, too. Whatever works, you know. My fantasy session now is working with her, recording The Maddox Brothers and Rose. Too bad it'll never happen. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#10
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue 12H
Paul wrote:
I tried shorting pin 2 to ground on one of these mics (is this the same thing you suggested to do with the modified XLR cable? shorting pin 2 to ground?). This makes one side of the pre-amp balanced transformer go to ground, instead of open. It makes the signal stronger, but not by a huge amount. ** You sure your mic pre uses an input transformer ? Very few do and active balanced circuit uses twin, identical inputs ( with phase reversal ) - so you can drive one or both. It makes little difference if you short the unused one to ground. .... Phil |
#11
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/27/2016 9:04 PM, Phil Allison wrote:
Paul wrote: I tried shorting pin 2 to ground on one of these mics (is this the same thing you suggested to do with the modified XLR cable? shorting pin 2 to ground?). This makes one side of the pre-amp balanced transformer go to ground, instead of open. It makes the signal stronger, but not by a huge amount. ** You sure your mic pre uses an input transformer ? Very few do and active balanced circuit uses twin, identical inputs ( with phase reversal ) - so you can drive one or both. It makes little difference if you short the unused one to ground. That's a good point, but it did get a bit louder after I did the mod..... |
#12
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
In article , Paul wrote:
Mike suggested drums, due to the low signal level when using with low-Z pre-amps. So maybe these would be good as tom-tom mics, or for the floor tom? If you put it into a low-Z preamp, not only will the signal level be low, but the frequency response will be altered because the microphone is too heavily loaded. Likely that means no top end. Use a step-down transformer or modify the mike to be a Prolog 12L. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#13
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/28/2016 8:23 AM, Scott Dorsey wrote:
In article , Paul wrote: Mike suggested drums, due to the low signal level when using with low-Z pre-amps. So maybe these would be good as tom-tom mics, or for the floor tom? If you put it into a low-Z preamp, not only will the signal level be low, but the frequency response will be altered because the microphone is too heavily loaded. Likely that means no top end. Use a step-down transformer or modify the mike to be a Prolog 12L. --scott Ok, I'm not sure if the transformers in these mics has another low-impedance tap I could use, but if not, perhaps I could just remove the transformer completely, and try driving pins 2 and 3 directly from the capsule, as the differential signal? |
#14
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
In article , Paul wrote:
On 3/28/2016 8:23 AM, Scott Dorsey wrote: In article , Paul wrote: Mike suggested drums, due to the low signal level when using with low-Z pre-amps. So maybe these would be good as tom-tom mics, or for the floor tom? If you put it into a low-Z preamp, not only will the signal level be low, but the frequency response will be altered because the microphone is too heavily loaded. Likely that means no top end. Use a step-down transformer or modify the mike to be a Prolog 12L. Ok, I'm not sure if the transformers in these mics has another low-impedance tap I could use, but if not, perhaps I could just remove the transformer completely, and try driving pins 2 and 3 directly from the capsule, as the differential signal? Maybe, that's why I suggested you get the service manual from the Shure website for the 12L, which is the low impedance version. Does it have a transformer? Is it a different model transformer? When you know these things, you can answer that question. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#15
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue 12H
Paul wrote:
Ok, I'm not sure if the transformers in these mics has another low-impedance tap I could use, but if not, perhaps I could just remove the transformer completely, and try driving pins 2 and 3 directly from the capsule, as the differential signal? ** You need to try that idea. The capsule is very likely 600ohm and not made by Shure - since the brochure is printed in Japan. ..... Phil |
#16
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/28/2016 5:03 PM, Scott Dorsey wrote:
In article , Paul wrote: On 3/28/2016 8:23 AM, Scott Dorsey wrote: In article , Paul wrote: Mike suggested drums, due to the low signal level when using with low-Z pre-amps. So maybe these would be good as tom-tom mics, or for the floor tom? If you put it into a low-Z preamp, not only will the signal level be low, but the frequency response will be altered because the microphone is too heavily loaded. Likely that means no top end. Use a step-down transformer or modify the mike to be a Prolog 12L. Ok, I'm not sure if the transformers in these mics has another low-impedance tap I could use, but if not, perhaps I could just remove the transformer completely, and try driving pins 2 and 3 directly from the capsule, as the differential signal? Maybe, that's why I suggested you get the service manual from the Shure website for the 12L, which is the low impedance version. Does it have a transformer? Is it a different model transformer? When you know these things, you can answer that question. --scott The Shure website only has the 12L user guide, which doesn't show a schematic. But the Prologue 10H and 10L looks very similar: http://cdn.shure.com/user_guide/uplo...7a2178_ec_.pdf And you can see they simply remove the transformer to go from high to low impedance, and separate the black wire from the case-ground tab on the capsule, so they can drive pins 2 and 3 differentially from the capsule directly. Ok, since I have two of these mics, I will likely try this! |
#17
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/28/2016 8:55 PM, Phil Allison wrote:
Paul wrote: Ok, I'm not sure if the transformers in these mics has another low-impedance tap I could use, but if not, perhaps I could just remove the transformer completely, and try driving pins 2 and 3 directly from the capsule, as the differential signal? ** You need to try that idea. The capsule is very likely 600ohm and not made by Shure - since the brochure is printed in Japan. The Shure website only has the 12L user guide, which doesn't show a schematic. But the Prologue 10H and 10L looks very similar: http://cdn.shure.com/user_guide/uplo...7a2178_ec_.pdf And you can see they simply remove the transformer to go from high to low impedance, and separate the black wire from the case-ground tab on the capsule, so they can drive pins 2 and 3 differentially from the capsule directly. Ok, since I have two of these mics, I will likely try this! |
#18
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
In article , Mike Rivers wrote:
On 3/27/2016 9:25 AM, Paul wrote: Ok, great. Thanks for the engineering review and insight...how many years have you been in pro audio? I'll mod both mics to have pin2=Hot, and pin3=grounded, to match the cable I have. Oh, about 60 years, I guess. Hard to remember just when I started, or when I became "pro." Oh, come on, Mike. When was the first time you got paid for recording or PA work? I remember the first time I got paid, I was 14... --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#19
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
In article , Paul wrote:
On 3/28/2016 5:03 PM, Scott Dorsey wrote: In article , Paul wrote: On 3/28/2016 8:23 AM, Scott Dorsey wrote: In article , Paul wrote: Mike suggested drums, due to the low signal level when using with low-Z pre-amps. So maybe these would be good as tom-tom mics, or for the floor tom? If you put it into a low-Z preamp, not only will the signal level be low, but the frequency response will be altered because the microphone is too heavily loaded. Likely that means no top end. Use a step-down transformer or modify the mike to be a Prolog 12L. Ok, I'm not sure if the transformers in these mics has another low-impedance tap I could use, but if not, perhaps I could just remove the transformer completely, and try driving pins 2 and 3 directly from the capsule, as the differential signal? Maybe, that's why I suggested you get the service manual from the Shure website for the 12L, which is the low impedance version. Does it have a transformer? Is it a different model transformer? When you know these things, you can answer that question. --scott The Shure website only has the 12L user guide, which doesn't show a schematic. But the Prologue 10H and 10L looks very similar: http://cdn.shure.com/user_guide/uplo...7a2178_ec_.pdf And you can see they simply remove the transformer to go from high to low impedance, and separate the black wire from the case-ground tab on the capsule, so they can drive pins 2 and 3 differentially from the capsule directly. Ok, since I have two of these mics, I will likely try this! It's certainly worth trying. The 12 might be different than the 10, but I doubt it. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#20
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/29/2016 9:30 AM, Scott Dorsey wrote:
Oh, come on, Mike. When was the first time you got paid for recording or PA work? I remember the first time I got paid, I was 14... My rabbi used to go down to U.S. Recording Co on South Capitol Street and have them cut a disk of the chants we had to learn for our bar mitzva service. Since each week, we would read from a different portion of the torah, he couldn't just cut one disk and sell it to everyone. When I was about 12 and preparing for my bar mitzvah, he got a tape recorder so he could record the chants at home and then take the tape to the studio. I helped him set up his recorder, showed him how to use it, and how to make edits so he wouldn't have to re-record the whole thing if he made a mistake. It was a Wilcox-Gay. He charged $15 for the disks, but in exchange for my help, gave me mine for free. I guess that was my first paid session, though it was more consulting than recording. So, yeah, 61 years. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#21
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/29/2016 6:32 AM, Scott Dorsey wrote:
In article , Paul wrote: On 3/28/2016 5:03 PM, Scott Dorsey wrote: In article , Paul wrote: On 3/28/2016 8:23 AM, Scott Dorsey wrote: In article , Paul wrote: Mike suggested drums, due to the low signal level when using with low-Z pre-amps. So maybe these would be good as tom-tom mics, or for the floor tom? If you put it into a low-Z preamp, not only will the signal level be low, but the frequency response will be altered because the microphone is too heavily loaded. Likely that means no top end. Use a step-down transformer or modify the mike to be a Prolog 12L. Ok, I'm not sure if the transformers in these mics has another low-impedance tap I could use, but if not, perhaps I could just remove the transformer completely, and try driving pins 2 and 3 directly from the capsule, as the differential signal? Maybe, that's why I suggested you get the service manual from the Shure website for the 12L, which is the low impedance version. Does it have a transformer? Is it a different model transformer? When you know these things, you can answer that question. --scott The Shure website only has the 12L user guide, which doesn't show a schematic. But the Prologue 10H and 10L looks very similar: http://cdn.shure.com/user_guide/uplo...7a2178_ec_.pdf And you can see they simply remove the transformer to go from high to low impedance, and separate the black wire from the case-ground tab on the capsule, so they can drive pins 2 and 3 differentially from the capsule directly. Ok, since I have two of these mics, I will likely try this! It's certainly worth trying. The 12 might be different than the 10, but I doubt it. --scott Aren't high-Z mics something like Beta tapes were back in the day? Aren't they practically useless these days? No CMRR, etc. Or do you think I should keep one High-Z mic just in case I run into a high-Z input? The only time I can imagine needing a high-Z mic is if I wanted to use a guitar amp to sing through, and didn't have a balun transformer (XLR to 1/4"). |
#22
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue 12H
Paul wrote:
Aren't high-Z mics something like Beta tapes were back in the day? Aren't they practically useless these days? No CMRR, etc. Or do you think I should keep one High-Z mic just in case I run into a high-Z input? The only time I can imagine needing a high-Z mic is if I wanted to use a guitar amp to sing through, and didn't have a balun transformer (XLR to 1/4"). ** There are not many uses for them and very few left on sale. The original uses were with things like with consumer grade tape recorders and paging amplifiers. FYI: Nothing stops you using a low Z mic with a guitar amp - for close miced speech or singing they have enough output level. ..... Phil |
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/29/2016 11:32 PM, Phil Allison wrote:
Paul wrote: Aren't high-Z mics something like Beta tapes were back in the day? Aren't they practically useless these days? No CMRR, etc. Or do you think I should keep one High-Z mic just in case I run into a high-Z input? The only time I can imagine needing a high-Z mic is if I wanted to use a guitar amp to sing through, and didn't have a balun transformer (XLR to 1/4"). ** There are not many uses for them and very few left on sale. The original uses were with things like with consumer grade tape recorders and paging amplifiers. FYI: Nothing stops you using a low Z mic with a guitar amp - for close miced speech or singing they have enough output level. Oh, I've used Low-Z mics with a guitar amp quite often, using a transformer balun. It just seems like High-Z isn't very useful, and may not be worth keeping in my mic locker..... |
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue 12H
Paul wrote:
** There are not many uses for them and very few left on sale. The original uses were with things like with consumer grade tape recorders and paging amplifiers. FYI: Nothing stops you using a low Z mic with a guitar amp - for close miced speech or singing they have enough output level. Oh, I've used Low-Z mics with a guitar amp quite often, using a transformer balun. ** I meant use with no balun transformer. It is often quite unnecessary and only spoils the quality. That low Z mics must be only be used with balanced inputs or gain some benefit from so doing is one of the most persistent myths in audio. ..... Phil ..... Phil |
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/30/2016 12:05 AM, Phil Allison wrote:
Paul wrote: ** There are not many uses for them and very few left on sale. The original uses were with things like with consumer grade tape recorders and paging amplifiers. FYI: Nothing stops you using a low Z mic with a guitar amp - for close miced speech or singing they have enough output level. Oh, I've used Low-Z mics with a guitar amp quite often, using a transformer balun. ** I meant use with no balun transformer. It is often quite unnecessary and only spoils the quality. That low Z mics must be only be used with balanced inputs or gain some benefit from so doing is one of the most persistent myths in audio. Ok, I'll try it without a balun. But how many High-Z mics do you have in your locker, and how often do you need to use them? Have you ever run into a situation where only a High-Z mic will do the job? |
#26
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/30/2016 2:02 AM, Paul wrote:
Aren't high-Z mics something like Beta tapes were back in the day? Not really. Beta was actually a better system than VHS. However, like Beta videotape (and ultimately, VHS, too), high impedance mics have become obsolete because the equipment that they were used with has become obsolete. We had high impedance mics to use with equipment that was built without transformers to save cost. Or do you think I should keep one High-Z mic just in case I run into a high-Z input? The only time I can imagine needing a high-Z mic is if I wanted to use a guitar amp to sing through, and didn't have a balun transformer (XLR to 1/4"). Since most high impedance (only) mics usually aren't of particularly good quality, I'd rather have a decent transformer around than be burdened with a mic that I'd rather not use, even in an emergency situation. I was once working at a country music festival in rural Virginia where the temporary power they brought in for the PA system went out just before Jerry Lee Lewis was about to go on stage. They had a generator for minimal lighting, so we plugged a guitar amplifier into that circuit, put a direct box backwards between an SM-58 and the amplifier for his voice, and The Killer put on a killer show for the 100 or so people who gathered at the edge of the stage. And on the more practical side, Chicago style harmonica players have traditionally played with a cheap high impedance radio dispatcher's mic (the Shure Green Bullet) plugged into a guitar amplifier. They wouldn't let Shure discontinue it. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#27
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue 12H
Paul wrote:
Phil Allison wrote: Ok, I'll try it without a balun. ** Old Chinese staying: "Never try = never know". But how many High-Z mics do you have in your locker, and how often do you need to use them? ** None. Have you ever run into a situation where only a High-Z mic will do the job? ** As Mike R said, a harmonic mike is one - if the player is using one of those puny, tube practice amps made in the 1950s and needs to overdrive the **** out of it. .... Phil |
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
In article , Paul wrote:
Aren't high-Z mics something like Beta tapes were back in the day? Aren't they practically useless these days? No CMRR, etc. They are still very common in the communications world, for short runs from a desk mike to a radio, etc. Or do you think I should keep one High-Z mic just in case I run into a high-Z input? The only time I can imagine needing a high-Z mic is if I wanted to use a guitar amp to sing through, and didn't have a balun transformer (XLR to 1/4"). Maybe, but you should always keep matching transformers around. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#29
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 3/30/2016 4:07 AM, Mike Rivers wrote:
On 3/30/2016 2:02 AM, Paul wrote: Aren't high-Z mics something like Beta tapes were back in the day? Not really. Beta was actually a better system than VHS. However, like Beta videotape (and ultimately, VHS, too), high impedance mics have become obsolete because the equipment that they were used with has become obsolete. We had high impedance mics to use with equipment that was built without transformers to save cost. Or do you think I should keep one High-Z mic just in case I run into a high-Z input? The only time I can imagine needing a high-Z mic is if I wanted to use a guitar amp to sing through, and didn't have a balun transformer (XLR to 1/4"). Since most high impedance (only) mics usually aren't of particularly good quality, I'd rather have a decent transformer around than be burdened with a mic that I'd rather not use, even in an emergency situation. I was once working at a country music festival in rural Virginia where the temporary power they brought in for the PA system went out just before Jerry Lee Lewis was about to go on stage. They had a generator for minimal lighting, so we plugged a guitar amplifier into that circuit, put a direct box backwards between an SM-58 and the amplifier for his voice, and The Killer put on a killer show for the 100 or so people who gathered at the edge of the stage. And on the more practical side, Chicago style harmonica players have traditionally played with a cheap high impedance radio dispatcher's mic (the Shure Green Bullet) plugged into a guitar amplifier. They wouldn't let Shure discontinue it. Ok, thanks everyone for the feedback, it's been very informative. I'll likely modify both of these 12Hs to Low-Z, and maybe sell one on Ebay......those Ebay people will buy anything! Haha! |
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Silly Questions about High Impedance Dynamic Mic, Shure Prologue12H
On 30-03-2016 14:11, Scott Dorsey wrote:
In article , Paul wrote: Aren't high-Z mics something like Beta tapes were back in the day? Aren't they practically useless these days? No CMRR, etc. They are still very common in the communications world, for short runs from a desk mike to a radio, etc. Or do you think I should keep one High-Z mic just in case I run into a high-Z input? The only time I can imagine needing a high-Z mic is if I wanted to use a guitar amp to sing through, and didn't have a balun transformer (XLR to 1/4"). Maybe, but you should always keep matching transformers around. Always watch out, if you encounter a Sennheiser cable transformer at a garage sale, buy it, it will probably be practical some day .... and impossible to get on the day you need it. --scott Kind regards Peter Larsen |
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