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#1
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dynamic mic self noise (and my re15)
I don't know enough about microphones, I do know a moving coil microphone is a fairly simple electro mechanical device.....
If I could change one and only one thing about my re15's it's that they seem to be a bit noisy. Not a terrible deal breaker, but those mics are so good otherwise it would be nice to have a specimen that went all the way. Would changing the transformer help? I don't want to use an re20 (except when I want to use an re20)- the response is crispier and that mic is more difficult to place. And then of course the low output introduces the option for preamp noise to compound the issue. I'm using good preamps (prism orpheus) but if you get up to about 50db of gain they start to add their own noticeable noise. But the mics themselves are a bit white noisy. What causes that to be the case and is there anything that can be done? It's not like anyone out there is making a comparable product..... N |
#2
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dynamic mic self noise (and my re15)
Nate Najar wrote:
I don't know enough about microphones, I do know a moving coil microphone is a fairly simple electro mechanical device..... If I could change one and only one thing about my re15's it's that they seem to be a bit noisy. Not a terrible deal breaker, but those mics are so good otherwise it would be nice to have a specimen that went all the way. Would changing the transformer help? I don't want to use an re20 (except when I want to use an re20)- the response is crispier and that mic is more difficult to place. And then of course the low output introduces the option for preamp noise to compound the issue. I'm using good preamps (prism orpheus) but if you get up to about 50db of gain they start to add their own noticeable noise. But the mics themselves are a bit white noisy. What causes that to be the case and is there anything that can be done? It's not like anyone out there is making a comparable product..... N There could be several possible causes, what does the noise sound like? -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#3
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dynamic mic self noise (and my re15)
In article ,
Nate Najar wrote: And then of course the low output introduces the option for preamp noise to compound the issue. I'm using good preamps (prism orpheus) but if you get up to about 50db of gain they start to add their own noticeable noise. But the mics themselves are a bit white noisy. In the old days we used to have 30/300 ohm input matching transformers on the amp input for those low impedance STC mics in use then. But that was with valve pre-amps. When transistors came along they were dispensed with - the transistor amps said to have a good enough noise performance even with the 30 ohm mics. -- *Acupuncture is a jab well done* Dave Plowman London SW To e-mail, change noise into sound. |
#4
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dynamic mic self noise (and my re15)
On 1/16/2015 4:13 AM, Nate Najar wrote:
If I could change one and only one thing about my re15's it's that they seem to be a bit noisy. Not a terrible deal breaker, but those mics are so good otherwise it would be nice to have a specimen that went all the way. Would changing the transformer help? I don't want to use an re20 (except when I want to use an re20)- the response is crispier and that mic is more difficult to place. The microphone itself doesn't generate noise since it's totally passive. The noise is actually from the input stage of the mic preamp as it sees the mic's source impedance. Now you know one more thing about microphones. When you need to run the preamp near maximum gain in order to get a decent record level, the hiss increases. Changing the transformer would change the mic. You might like it or you might not. A small step up transformer between the mic and preamp, maybe a 1:2 ratio, would give you 6 dB of noise-free gain. A Jensen JT-16ATB in a box would be an easy to build project and probably wouldn't change the sound of the mic or preamp much. You might even like your Prism with a transformer input with other mics. I wouldn't mess with changing the transformer in the mic, though. Now that Jensen is owned by Radial, maybe there's a ready-made Radial "problem solver" box that you could try. I'll try to remember to look for one or ask at their booth at NAMM. I'm using good preamps (prism orpheus) but if you get up to about 50db of gain they start to add their own noticeable noise. But the mics themselves are a bit white noisy. I found, when I had a Lyra here for a review, that I could hear (and hence record) a little hiss with my "M260-DX" ribbon mics, and even with an SM-57. Preamps like the AEA TRP are designed to alleviate that problem. A less expensive alternative for you to try is the Cloudlifter. That's something you can buy, try, and return if it doesn't make the mic more usable. I had the opportunity to plug the M260-DX into one once and it definitely gave me significantly more level above the hiss. I didn't spend any time trying to hear any change in the sound of the mic, but since Cloud makes it to use with their own ribbon mics which are pretty good RCA style ribbon mics, he must think it's OK. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#5
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dynamic mic self noise (and my re15)
Mike Rivers wrote:
On 1/16/2015 4:13 AM, Nate Najar wrote: If I could change one and only one thing about my re15's it's that they seem to be a bit noisy. Not a terrible deal breaker, but those mics are so good otherwise it would be nice to have a specimen that went all the way. Would changing the transformer help? I don't want to use an re20 (except when I want to use an re20)- the response is crispier and that mic is more difficult to place. The microphone itself doesn't generate noise since it's totally passive. Moving-coil microphones do generate noise: the resistance of the coil generates Johnson noise due to thermal movement of the electrons. There is also noise from the Brownian movement of the air molecules impacting on the diaphragm (you may consider that this is not actually generated by the microphone, but it is an inevitably part of the inherent microphone noise in normal use). In a well-designed microphone, the Johnson noise and the Brownian noise will be of similar magnitude. In a well designed pre-amp, the electronic noise should be significantly lower than the total inherent microphone noise. Igor M and I did some experiments on popular moving coil mics and found that the inherent noise of most of them was too high to use them for talking book work, regardless of how good the pre-amp was. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#6
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dynamic mic self noise (and my re15)
On 1/16/2015 3:47 PM, Adrian Tuddenham wrote:
Moving-coil microphones do generate noise: the resistance of the coil generates Johnson noise due to thermal movement of the electrons. There is also noise from the Brownian movement of the air molecules impacting on the diaphragm (you may consider that this is not actually generated by the microphone, but it is an inevitably part of the inherent microphone noise in normal use). In a well-designed microphone, the Johnson noise and the Brownian noise will be of similar magnitude. In a well designed pre-amp, the electronic noise should be significantly lower than the total inherent microphone noise. I know about the physics of moving molecules, both air and electrical. But every time I say that to someone knowledgeable, they always say that it's the current noise when the input of the input transistor(s) is connected to the microphone that does most of the damage. There's between 3 and 6 dB less noise coming out of a preamp with the input shorted than when it has 150 ohms or so to develop voltage across. But, for sure, if you really need quiet output with a quiet source at a reasonable working distance, you need a microphone with higher output voltage than most dynamics can provide. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#7
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dynamic mic self noise (and my re15)
On Thursday, January 15, 2015 at 10:13:59 PM UTC-5, Nate Najar wrote:
I don't know enough about microphones, I do know a moving coil microphone is a fairly simple electro mechanical device..... If I could change one and only one thing about my re15's it's that they seem to be a bit noisy. Not a terrible deal breaker, but those mics are so good otherwise it would be nice to have a specimen that went all the way. Would changing the transformer help? I don't want to use an re20 (except when I want to use an re20)- the response is crispier and that mic is more difficult to place. And then of course the low output introduces the option for preamp noise to compound the issue. I'm using good preamps (prism orpheus) but if you get up to about 50db of gain they start to add their own noticeable noise. But the mics themselves are a bit white noisy. What causes that to be the case and is there anything that can be done? It's not like anyone out there is making a comparable product..... N I learned something today. This is helpful, thanks! |
#8
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dynamic mic self noise (and my re15)
Mike Rivers wrote:
On 1/16/2015 3:47 PM, Adrian Tuddenham wrote: Moving-coil microphones do generate noise: the resistance of the coil generates Johnson noise due to thermal movement of the electrons. There is also noise from the Brownian movement of the air molecules impacting on the diaphragm (you may consider that this is not actually generated by the microphone, but it is an inevitably part of the inherent microphone noise in normal use). In a well-designed microphone, the Johnson noise and the Brownian noise will be of similar magnitude. In a well designed pre-amp, the electronic noise should be significantly lower than the total inherent microphone noise. I know about the physics of moving molecules, both air and electrical. But every time I say that to someone knowledgeable, they always say that it's the current noise when the input of the input transistor(s) is connected to the microphone that does most of the damage. There's between 3 and 6 dB less noise coming out of a preamp with the input shorted than when it has 150 ohms or so to develop voltage across. It depend entirely on the pre-amp and what it was designed to do. A pre-amp designed to match 150 ohms should give *more* noise when it is shorted then it does when terminated with 150 ohms. This is because the current and voltage noise sources should be optimally balanced at the correct terminating impedance and any move away from that impedance will give poorer noise figures (Do not be mis-led by looking only at voltage and ignoring power, which is the only true measure of noise and signal.) If this doesn't happen, the pre-amp is not correctly matched. But, for sure, if you really need quiet output with a quiet source at a reasonable working distance, you need a microphone with higher output voltage than most dynamics can provide. Or a dynamic mic with the same output voltage from a lower source impedance - again, *power* is the key to everything when you are trying to keep the noise down. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#9
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dynamic mic self noise (and my re15)
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#10
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dynamic mic self noise (and my re15)
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#11
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dynamic mic self noise (and my re15)
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#12
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dynamic mic self noise (and my re15)
Whether the Johnson noise or the current noise predominates, or the preamp's voltage noise, will depend entirely on the design of the preamp. But the fact is that dynamic mics do generate self-noise via the DC resistances of their coils and/or transformers.
And yes, a Cloudlifter may ease the problem; it has gain as well as selectable loading. Warning: just patching a transformer into the circuit, say a 1:2, as someone suggested, probably won't give good results. If the preamp has an input impedance of 1500 ohms (typical), a 1:2 transformer will show the mic a load impedance of (1500 ohms/4), or 375 ohms. The mic probably won't like that load, and it'll drop the signal level, which will aggravate the preamp noise problem as you need to dial in more gain. Plus the transformer has DC resistance of its own that adds to the mess. Go with the Cloudlifter. Peace, Paul |
#13
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dynamic mic self noise (and my re15)
On 1/16/2015 7:18 PM, Les Cargill wrote:
Has anyone tried a Cloudlifter? Does it only solve impedance problems ( (???)_, or does it help with noise as well? I used one for an hour and a half with my Stephen Sank modified Beyer M260. I was able to use less gain on the Mackie mixer's mic preamp for the same mix level, and got less hiss in the bargain. I'd say that was a good thing. I didn't attempt to evaluate whether it changed the "sound" of the mic. The bottom line is that it worked better with the Cloudlifter than without, and the quiet banjo I was miking sounded fine. -- For a good time, visit http://mikeriversaudio.wordpress.com |
#14
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dynamic mic self noise (and my re15)
Nate Najar wrote:
I don't know enough about microphones, I do know a moving coil microphone is a fairly simple electro mechanical device..... If I could change one and only one thing about my re15's it's that they seem to be a bit noisy. Not a terrible deal breaker, but those mics are so good otherwise it would be nice to have a specimen that went all the way. Would changing the transformer help? I don't want to use an re20 (except when I want to use an re20)- the response is crispier and that mic is more difficult to place. And then of course the low output introduces the option for preamp noise to compound the issue. I'm using good preamps (prism orpheus) but if you get up to about 50db of gain they start to add their own noticeable noise. But the mics themselves are a bit white noisy. What causes that to be the case and is there anything that can be done? It's not like anyone out there is making a comparable product..... N How much more gain do you desire between mic and conversion? So far I have not been impressed that much with the "good" preamps in most convertors. Most of those I have met, admittedly casually, seem almost as good as the preamps in a Mackie Onyx 1620i. I know an original Great River is not going to hiss at me wide open, unless the mic is hissing at the preamp. -- shut up and play your guitar * HankAlrich.Com HankandShaidriMusic.Com YouTube.Com/WalkinayMusic |
#15
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dynamic mic self noise (and my re15)
Well the reason I'm asking about mic noise and assuming it isn't all preamp noise is that when I plug in a 4038 with the same amount of gain, it isn't as hissy.....
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#16
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dynamic mic self noise (and my re15)
Nate Najar wrote:
Well the reason I'm asking about mic noise and assuming it isn't all preamp noise is that when I plug in a 4038 with the same amount of gain, it isn't as hissy..... RE15 roll-off switch set to Flat? A look at specs says they offer the preamp different source impedances, 150 versus 300 ohms, probably different sensitivities and max SPL specs, too. http://www.coutant.org/data/re15.pdf http://www.coleselectroacoustics.com...s/4038Spec.pdf -- shut up and play your guitar * HankAlrich.Com HankandShaidriMusic.Com YouTube.Com/WalkinayMusic |
#17
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dynamic mic self noise (and my re15)
On 18/01/2015 9:39 AM, Nate Najar wrote:
Well the reason I'm asking about mic noise and assuming it isn't all preamp noise is that when I plug in a 4038 with the same amount of gain, it isn't as hissy..... Presumably the mics are different internal impedances then. Trevor. |
#18
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dynamic mic self noise (and my re15)
On Sunday, January 18, 2015 at 12:49:53 AM UTC-5, Trevor wrote:
On 18/01/2015 9:39 AM, Nate Najar wrote: Well the reason I'm asking about mic noise and assuming it isn't all preamp noise is that when I plug in a 4038 with the same amount of gain, it isn't as hissy..... Presumably the mics are different internal impedances then. Trevor. they are. the RE15 is 150ohms and the 4038 is 300ohms. I don't know how that affects the preamp in terms of noise though. That's basically why I'm asking the questions. Don't get me wrong, it isn't too noisy to not use, not at all, but it's much noisier than most of my mics and I just am trying to educate myself as to why. |
#19
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dynamic mic self noise (and my re15)
In article ,
Nate Najar wrote: Well the reason I'm asking about mic noise and assuming it isn't all preamp noise is that when I plug in a 4038 with the same amount of gain, it isn't as hissy..... Is that a 30 or 300 ohm 4038? -- *When everything's coming your way, you're in the wrong lane * Dave Plowman London SW To e-mail, change noise into sound. |
#20
Posted to rec.audio.pro
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dynamic mic self noise (and my re15)
Nate Najar wrote:
Well the reason I'm asking about mic noise and assuming it isn't all preamp noise is that when I plug in a 4038 with the same amount of gain, it isn't as hissy..... RE15 roll-off switch set to Flat? A look at specs says they offer the preamp different source impedances, 150 versus 300 ohms, probably different sensitivities and max SPL specs, too. It's the source impedance that makes the difference in preamp noise. Notice with neither microphone plugged in, the noise is probably much higher. Marshall Leach has a paper on preamp input stage design where he actually goes through all the math for noise on fet, tube, and transistor input stages with and without transformers. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#21
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dynamic mic self noise (and my re15)
Nate Najar wrote:
Well the reason I'm asking about mic noise and assuming it isn't all preamp noise is that when I plug in a 4038 with the same amount of gain, it isn't as hissy..... If you want to see a pre-amp that was designed specifically to give the best possible S/N ratio from a 4038, have a look at the AMC/5 in: http://www.poppyrecords.co.uk/other/BBCamplifiers.pdf The key to its low noise is the combination of voltage and current feedback, which gets around the problem of noise generated in input-loading resistors. A lot of modern pre-amps don't bother with this and think that by choosing a low-noise input transistor and slapping a loading resistor across it, everything will be all right. The S/N ratio from this method is always at least 6dB worse than the best that could have been achieved by a good feedback design. Your pre-amp might fall into this category or it might have been designed for lowest noise at an impedance other than the one you are using it at - and the 4038 is nearer than the RE15 to that impedance. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#22
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dynamic mic self noise (and my re15)
Les Cargill wrote:
Has anyone tried a Cloudlifter? Does it only solve impedance problems ( (???)_, or does it help with noise as well? Or is it just another denuded emperor? Because the cloudlifter has a high-Z input stage, it will be noisier than a perfectly matched preamp. However, in practice you'll find that it's often much quieter than the preamp in an inexpensive console, even if it's still a lot noiser than the input to a John Hardy or Millennia preamp, so it can still be a useful tool for that. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#23
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dynamic mic self noise (and my re15)
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#24
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dynamic mic self noise (and my re15)
On 1/20/2015 8:08 PM, Les Cargill wrote:
Because the cloudlifter has a high-Z input stage, it will be noisier than a perfectly matched preamp. Then why does it have a big "Z" knob on the top? They don't publish the input impedance of the standard Cloudlifter, but as I recall, it's "pretty normal," maybe 1500 or 3,000 Ohms. Roger told me once, but I forgot. The one with the big Z on it is the Cloudlifter-Z. This has a pot hanging across a fairly high input impedance to vary the load on the mic from 150 ohms to 15 k ohms. -- "Today's production equipment is IT based and cannot be operated without a passing knowledge of computing, although it seems that it can be operated without a passing knowledge of audio" - John Watkinson Drop by http://mikeriversaudio.wordpress.com now and then |
#25
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dynamic mic self noise (and my re15)
Mike Rivers wrote:
On 1/20/2015 8:08 PM, Les Cargill wrote: Because the cloudlifter has a high-Z input stage, it will be noisier than a perfectly matched preamp. Then why does it have a big "Z" knob on the top? They don't publish the input impedance of the standard Cloudlifter, but as I recall, it's "pretty normal," maybe 1500 or 3,000 Ohms. Roger told me once, but I forgot. The one with the big Z on it is the Cloudlifter-Z. This has a pot hanging across a fairly high input impedance to vary the load on the mic from 150 ohms to 15 k ohms. So it is at least 6dB noiser than it needs to be. If they had varied a current-determining component in the feedback loop, the results would be a lot better. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#26
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dynamic mic self noise (and my re15)
Les Cargill wrote:
(Scott Dorsey) wrote: Les Cargill wrote: Has anyone tried a Cloudlifter? Does it only solve impedance problems ( (???)_, or does it help with noise as well? Or is it just another denuded emperor? Because the cloudlifter has a high-Z input stage, it will be noisier than a perfectly matched preamp. Then why does it have a big "Z" knob on the top? That adds a shunt resistor in parallel with the input. So the microphone sees a lower impedance load, but the noise is not decreased (and is actually slightly increased). The only way to get a real adjustable input Z that maintains noise performance at all settings is to use a multitap transformer. And that has other issues. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#27
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dynamic mic self noise (and my re15)
In article , Mike Rivers wrote:
On 1/21/2015 12:05 PM, Scott Dorsey wrote: That adds a shunt resistor in parallel with the input. So the microphone sees a lower impedance load, but the noise is not decreased (and is actually slightly increased). The only way to get a real adjustable input Z that maintains noise performance I've only found one microphone, a CAD ribbon, that sounded better with a low impedance load than it did with a conventional 1.5-2.5k ohm mic preamp input. I think it's a gimmick, but if it makes a too-bright mic sound less bright, I suppose it's good for those who have that problem (or that mic). The SM-57 sure sounds better with a low-Z load! The thing is that overall, adding 20 dB of output level to the preamp input when you need it while increasing the preamp noise by only a few dB, is better for most everyone. The only reason to fuss with that is if you insist on only using the best designs (or nothing). It sure would be better if more people used better preamps, though. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#28
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dynamic mic self noise (and my re15)
On 1/21/2015 1:56 PM, Scott Dorsey wrote:
The SM-57 sure sounds better with a low-Z load! The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The only preamp I have with a selectable input impedance is a Mackie 800R, and they missed the SM-57 sweet spot on that one (probably never knew about Paul's tests). As I recall, its choices are 300, 500, 1300, and 2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and 1300 ohms, and like an SM-57 at 2400 ohms. -- "Today's production equipment is IT based and cannot be operated without a passing knowledge of computing, although it seems that it can be operated without a passing knowledge of audio" - John Watkinson Drop by http://mikeriversaudio.wordpress.com now and then |
#29
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dynamic mic self noise (and my re15)
On Wed, 21 Jan 2015 21:10:09 -0500 "Mike Rivers" wrote
in article On 1/21/2015 1:56 PM, Scott Dorsey wrote: The SM-57 sure sounds better with a low-Z load! The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The only preamp I have with a selectable input impedance is a Mackie 800R, and they missed the SM-57 sweet spot on that one (probably never knew about Paul's tests). As I recall, its choices are 300, 500, 1300, and 2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and 1300 ohms, and like an SM-57 at 2400 ohms. This may be a silly question - squelch it if so, but what makes "good" preamps so expensive? I presume all the designers know of the good parts to use and of good designs (wrong?) but beyond that what accounts for the price? ..better design? good testing? careful component matching? just askin' |
#30
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dynamic mic self noise (and my re15)
On Wednesday, January 21, 2015 at 8:09:39 PM UTC-6, Mike Rivers wrote:
On 1/21/2015 1:56 PM, Scott Dorsey wrote: The SM-57 sure sounds better with a low-Z load! The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The only preamp I have with a selectable input impedance is a Mackie 800R, and they missed the SM-57 sweet spot on that one (probably never knew about Paul's tests). As I recall, its choices are 300, 500, 1300, and 2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and 1300 ohms, and like an SM-57 at 2400 ohms. I think they may have known; my tests were done at 2,000 and 500 ohms (the only two choices on the UA 2-610 preamp I used). Incidentally, I don't know if those settings include the phantom power resistors, but in any case adding those to a 500 ohm load makes it 482 ohms, which I'd call not enough change to shake a stick at. Incidentally, the 699 ohm Gizmo brought the 2,000 ohm load down to about 518 ohms. That was as close to 500 ohms as I could get with the resistors my surplus store had in stock. As the "Taming of the Shure" article said, I found the 500 ohm setting a great improvement over 2,000 ohms. Dunno if that's the exact "sweet spot" for an SM57, but to my ears it's close. Incidentally, I've tried changing the loading on other mics, with a null result; on most mics I tried (explicitly including the BETA 57A), changing the load from 2,000 to 500 ohms made little or no difference. One condenser mic (the Shure SM81 sounded worse at 500 than 2,000, but the only other mic I tried that was somewhat improved by a lower impedance load was an AKG D112 -- and it sounded a bit overdamped to me at 500 ohms. Would like to spend some time trying it at various intermediate loads. Peace, Paul |
#31
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dynamic mic self noise (and my re15)
On Wednesday, January 21, 2015 at 9:19:54 PM UTC-6, Jason wrote:
This may be a silly question - squelch it if so, but what makes "good" preamps so expensive? I presume all the designers know of the good parts to use and of good designs (wrong?) but beyond that what accounts for the price? ..better design? good testing? careful component matching? just askin' Depends on the preamp. The designer of the original Great River preamp once talked about the discrete-component FET-input opamp he used, and noted that it needed a whole lot of parts and careful hand-matching of the input devices to give him the kind of linearity he wanted. Then there were the input transformers at $100 a pop, with little discount for quantity purchases. Good transformers are hard to build, and there's no longer a mass market for them, so they're expensive. In transformerless preamps, the good ones also often require hand-matching of their input devices. That's labor, which costs money. What else drives up the prices of preamps? Good parts, including pots and switches that will take a lot of cycles without becoming noisy, and electrolytic capacitors that will last a long time. Those nice thick front panels cost money, and so does drilling holes in them. Robust power supplies, including good filtering to keep out line-borne and diode-generated garbage. If the preamp's transformerless, good filtering of the input signal to keep out RFI. As you mentioned, testing/quality control. And if the preamp has an inboard power supply rather than a wall wart, UL certification. There are the costs of labor and keeping a factory open. Then of course the manufacturers need to make some profit, or they'll be out of business. There are markups by distributors and dealers. I think pro audio gear still has about an 8-to-1 pricearts cost ratio; a $2,000 preamp probably has about $250 worth of parts in it, wholesale cost. Peace, Paul |
#32
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dynamic mic self noise (and my re15)
On Wednesday, January 21, 2015 at 9:58:58 PM UTC-6, Jeff Henig wrote:
Paul, I keep reading that ribbon mics like high impedance. Is that in any way accurate? Well, my experience with classic-style ribbons is limited, but it would bear out that idea. I borrowed Bill Schulenburg's RCA ribbon when I was testing out the Benchmark preamp, and it sounded a whale of a lot better than it did through a Grace preamp. The Benchmark's input impedance is about 6.8k; the Grace's is about 1.5k. So based on that one-time test, I'd go with high impedance loads for old-style ribbons. More modern ribbons seem to be optimized for modern-style preamps, with input Zs of 1.2k-2.4k,And active ribbons have their termination resistors inside, chosen by the designer, and work fine into just about anything. In fact, that's the idea. Peace, Paul |
#33
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dynamic mic self noise (and my re15)
Jason wrote:
On Wed, 21 Jan 2015 21:10:09 -0500 "Mike Rivers" wrote in article On 1/21/2015 1:56 PM, Scott Dorsey wrote: The SM-57 sure sounds better with a low-Z load! The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The only preamp I have with a selectable input impedance is a Mackie 800R, and they missed the SM-57 sweet spot on that one (probably never knew about Paul's tests). As I recall, its choices are 300, 500, 1300, and 2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and 1300 ohms, and like an SM-57 at 2400 ohms. This may be a silly question - squelch it if so, but what makes "good" preamps so expensive? I presume all the designers know of the good parts to use and of good designs (wrong?) but beyond that what accounts for the price? ..better design? good testing? careful component matching? just askin' I'm reasonably sure good preamps are still very much craft goods, where Mackie mixers have a minimum of human involvement in their manufacture. -- Les Cargill |
#35
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dynamic mic self noise (and my re15)
Mike Rivers wrote:
On 1/21/2015 12:05 PM, Scott Dorsey wrote: That adds a shunt resistor in parallel with the input. So the microphone sees a lower impedance load, but the noise is not decreased (and is actually slightly increased). The only way to get a real adjustable input Z that maintains noise performance I've only found one microphone, a CAD ribbon, that sounded better with a low impedance load than it did with a conventional 1.5-2.5k ohm mic preamp input. I think it's a gimmick, but if it makes a too-bright mic sound less bright, I suppose it's good for those who have that problem (or that mic). The thing is that overall, adding 20 dB of output level to the preamp input when you need it while increasing the preamp noise by only a few dB, is better for most everyone. The only reason to fuss with that is if you insist on only using the best designs (or nothing). Look at the input impedance of the Gordon preamp. Never heard one that sounded that good, more there there than I'd ever realized before. http://gordonaudio.com/specs.htm -- shut up and play your guitar * HankAlrich.Com HankandShaidriMusic.Com YouTube.Com/WalkinayMusic |
#36
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dynamic mic self noise (and my re15)
On 1/21/2015 10:19 PM, Jason wrote:
This may be a silly question - squelch it if so, but what makes "good" preamps so expensive? I presume all the designers know of the good parts to use and of good designs (wrong?) but beyond that what accounts for the price? ..better design? good testing? careful component matching? j Mostly it's the last little bit of performance in one or a few different ways that people who want something different. Part of the reason why we have so many expensive mic preamps is that 20 years ago there were a lot of mediocre preamps because that was all they could do for the price that would allow them to sell a whole lot of them. Today, you can make a very serviceable preamp for $25 worth of parts. Putting it in a box with a power supply, connectors, switches, etc. can add another $100, add in marketing and profit and $200 per channel will get 95% or more users a good recording, all other things being equal. The other 5% are willing to pay 5-10 times that for a special color, another 10 dB of gain without noise, and bragging rights. If you look inside a Gordon preamp, you'll easily see why it's worth $2500. If you look inside your heart, you'll wonder if you'd get more bang for your bucks with something else. Some will, some won't. -- "Today's production equipment is IT based and cannot be operated without a passing knowledge of computing, although it seems that it can be operated without a passing knowledge of audio" - John Watkinson Drop by http://mikeriversaudio.wordpress.com now and then |
#37
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dynamic mic self noise (and my re15)
In article ,
PStamler wrote: On Wednesday, January 21, 2015 at 9:58:58 PM UTC-6, Jeff Henig wrote: Paul, I keep reading that ribbon mics like high impedance. Is that in any way accurate? Well, my experience with classic-style ribbons is limited, but it would bear out that idea. I borrowed Bill Schulenburg's RCA ribbon when I was testing out the Benchmark preamp, and it sounded a whale of a lot better than it did through a Grace preamp. The Benchmark's input impedance is about 6.8k; the Grace's is about 1.5k. So based on that one-time test, I'd go with high impedance loads for old-style ribbons. More modern ribbons seem to be optimized for modern-style preamps, with input Zs of 1.2k-2.4k,And active ribbons have their termination resistors inside, chosen by the designer, and work fine into just about anything. In fact, that's the idea. Don't all classic ribbons have a built in transformer? If so you'd expect that to be designed to work best with the normal input impedance of the day. -- *24 hours in a day ... 24 beers in a case ... coincidence? * Dave Plowman London SW To e-mail, change noise into sound. |
#38
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dynamic mic self noise (and my re15)
Jason wrote:
On Wed, 21 Jan 2015 21:10:09 -0500 "Mike Rivers" wrote in article On 1/21/2015 1:56 PM, Scott Dorsey wrote: The SM-57 sure sounds better with a low-Z load! The SM-57 sounds better with the PROPER load (thanks, Paul Stamler). The only preamp I have with a selectable input impedance is a Mackie 800R, and they missed the SM-57 sweet spot on that one (probably never knew about Paul's tests). As I recall, its choices are 300, 500, 1300, and 2400 ohms. My SM-57 sounds dull at 300 ohms, about the same at 500 and 1300 ohms, and like an SM-57 at 2400 ohms. This may be a silly question - squelch it if so, but what makes "good" preamps so expensive? I presume all the designers know of the good parts to use and of good designs (wrong?) but beyond that what accounts for the price? ..better design? good testing? careful component matching? just askin' Some of it is smaller production runs. Costs don't get amortized among as many units. In the case of transformer-input preamp, a vast amount of the total cost is the transformer. The cost of the input transformer on the original Great River is greater than the total parts cost on those smaller Mackie consoles. Some of it is fancy metalwork, and these days a shocking amount of it is in the power supply. And, surprisingly, getting quiet transistors has become very difficult, since everything is digital and nobody wants to make transistors for high performance linear circuits. So we have $10 front end transistor arrays now. (In the case of the original Great River, Dan put a dozen $2 jfets in parallel for low noise... but you can't even get those jfets anymore). The industry is moving far away from low-noise low-frequency stuff, it is very difficult to find anything at reasonable prices. I keep being visited by sales reps trying to sell me three-cent transistors, and I tell them I'd be happy to pay a dollar for a transistor if they could get the 1/f noise down and they tell me that I only buy thousands of transistors, not millions, and they make parts for the people who buy millions. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#39
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dynamic mic self noise (and my re15)
Jeff Henig wrote:
Paul, I keep reading that ribbon mics like high impedance. Is that in any way accurate? For the most part, a traditional RCA-style ribbon will have more accurate high frequency response but more noise going into a high-Z load. Get Harry Olsen's book "Music, Physics and Engineering." There's a paperback reprint on Amazon for $5 and it will be the best $5 you ever spent. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#40
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dynamic mic self noise (and my re15)
On Wednesday, January 21, 2015 at 9:19:54 PM UTC-6, Jason wrote:
This may be a silly question - squelch it if so, but what makes "good"=20 preamps so expensive? I presume all the designers know of the good parts= I think a better way to look at this is to look at what makes cheap preamps so cheap. For many years, all of the professional audio gear was built and sold like the high end boutique gear today. What has changed is the introduction of cheap mass-produced gear. Take a look at what has been gone in order to make cheap gear cheap... a lot of it are things like eliminating IC sockets and internal connectorization since it's not intended to be maintained. Some of it is replacing expensive precision power supplies will wall warts. Some of it is in the control design and in the controls used; buttons are much cheaper than pots and dual pots that need to track are way more expensive than single pots. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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