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#1
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Question about impedance matching mic & pre
Just got an MXL R40 ribbon mic. Never had a ribbon before. I see the
mic specs say 250 ohms. My VTB-1 pre has settings of 50 & 200. I'm not versed in electronics, does this mean it's not optimally suited for this mic? I get sound out of it, I understand that a ribbon sounds much different than a condenser and needs more boost, I don't have a basis for comparison as to whether it sounds the way it's supposed to. Thanks |
#2
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Question about impedance matching mic & pre
On Dec 7, 10:12*am, muzician21 wrote:
Just got an MXL R40 ribbon mic. Never had a ribbon before. I see the mic specs say 250 ohms. My VTB-1 pre has settings of 50 & 200. I'm not versed in electronics, does this mean it's not optimally suited for this mic? I get sound out of it, I understand that a ribbon sounds much different than a condenser and needs more boost, I don't have a basis for comparison as to whether it sounds the way it's supposed to. Mics aren't operated into matching impedances. They're typically designed to operate into an impedance about 10 times their own. Your preamp has impedance settings of 50 and 200 ohms? Is there a third setting, unlabeled or with some other kind of name on it? That's probably something like 1500 ohms, and that's what you want for this mic (and most others). Peace, Paul |
#3
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BUYING RENAGEL ONLINE
ORDERING GENERIC RENAGEL ONLINE |
#4
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Question about impedance matching mic & pre
On 12/7/2011 11:12 AM, muzician21 wrote:
Just got an MXL R40 ribbon mic. Never had a ribbon before. I see the mic specs say 250 ohms. My VTB-1 pre has settings of 50& 200. I'm not versed in electronics, does this mean it's not optimally suited for this mic? I get sound out of it, I understand that a ribbon sounds much different than a condenser and needs more boost, I don't have a basis for comparison as to whether it sounds the way it's supposed to. Thanks Check your manual, http://www.studioprojects.com/pdf/vtb1_manual.pdf Page 4, 'Feature Control Description' mentions you should have the 50/200 switch set to 50 for 'low impedance ribbon mics.' Myself, I'd try it in both positions and use the one *I* like the sound of. |
#5
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Question about impedance matching mic & pre
PStamler wrote:
On Dec 7, 10:12 am, muzician21 wrote: Just got an MXL R40 ribbon mic. Never had a ribbon before. I see the mic specs say 250 ohms. My VTB-1 pre has settings of 50 & 200. I'm not versed in electronics, does this mean it's not optimally suited for this mic? I get sound out of it, I understand that a ribbon sounds much different than a condenser and needs more boost, I don't have a basis for comparison as to whether it sounds the way it's supposed to. Mics aren't operated into matching impedances. They're typically designed to operate into an impedance about 10 times their own. Your preamp has impedance settings of 50 and 200 ohms? Is there a third setting, unlabeled or with some other kind of name on it? That's probably something like 1500 ohms, and that's what you want for this mic (and most others). Maybe those numbers apply to the impedance of the source, instead of to the input? -- shut up and play your guitar * http://hankalrich.com/ http://www.youtube.com/walkinaymusic http://www.sonicbids.com/HankandShaidri |
#6
Posted to rec.audio.pro
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Question about impedance matching mic & pre
muzician21 wrote:
Just got an MXL R40 ribbon mic. Never had a ribbon before. I see the mic specs say 250 ohms. My VTB-1 pre has settings of 50 & 200. I'm not versed in electronics, does this mean it's not optimally suited for this mic? I get sound out of it, I understand that a ribbon sounds much different than a condenser and needs more boost, I don't have a basis for comparison as to whether it sounds the way it's supposed to. Many ribbon and moving coil mics do need to be operated into approximately the correct impedance (capacitor mics, in general do not). In the case of moving coil mics, the terminating impdance damps down some unavoidable resonances in the audio spectrum. If your termination impedance is a long way off the manufacturer's recomendations, you could get a slightly wonky frequency response. In the case of ribbon mics, the sensitivity is low and the correct matching is needed to transfer as much power as possible from the ribbon to the input stage of the pre-amp. If the matching is badly wrong, you could finish up with a less-than-optimum signal-to-noise ratio. Having said that, the matching isn't critical and a moderate error will make very little audible difference. In your case, the 200-ohm termination is as close as you need for a nominally 250-ohm microphone - in all probability the normal factory variations in the construction of the mic and ribbon will cause at least as much error as that. If this is your first experience of using a ribbon microphone, read the AES paper "The Bidirectional Microphone: A Forgotten Patriarch" by Ron Streicher & Wes Dooley, it is an excellent guide to the understanding and the correct use of ribbons: http://www.wesdooley.com/pdf/Bidirec...icrophones.pdf -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#7
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Question about impedance matching mic & pre
On 12/7/2011 11:12 AM, muzician21 wrote:
Just got an MXL R40 ribbon mic. Never had a ribbon before. I see the mic specs say 250 ohms. My VTB-1 pre has settings of 50& 200. They do that just to confuse you. The microphone probably has an output impedance of somewhere around 250 ohms. As far as the preamp goes, the specs read: Mic Input (Rear switch in 200 ohm position): 2000 ohms Mic Input (Rear switch in 50 ohm position): 300 ohms Now how is anyone supposed to make sense of that? What Studio Projects means is that in the 200 ohm position, it's suitable for connecting to a mic with an impedance of about 200 ohms (150 is more typical, yours at 250 is close enough) BECAUSE it has an input impedance of 2000 ohms. So misleading or "seems right, but for the wrong reason" as it may be, the 200 ohm position is correct for your microphone. I understand that a ribbon sounds much different than a condenser and needs more boost, Oh, poobah! It's true that classic ribbon mics do have a somewhat lower output level for a given sound pressure level than classic condenser mics, but because people like you (nothing personal) come up with questions like this that most dealers aren't smart enough to answer correctly, they've sort of dumbed down most mics so modern condenser mics are a little less sensitive than they used to be, and with modern magnet materials, they're able to make ribbon mics a little more sensitive than they used to be. If you're recording a quiet source, you'll probably need to run the gain pretty close to full up, maybe add some gain with the Output Level control. Don't worry about it. You're getting sound out of it, now go record something! -- "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 http://mikeriversaudio.wordpress.com - useful and interesting audio stuff |
#8
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Question about impedance matching mic & pre
On Dec 7, 8:31*pm, Mike Rivers wrote:
On 12/7/2011 11:12 AM, muzician21 wrote: Just got an MXL R40 ribbon mic. Never had a ribbon before. I see the mic specs say 250 ohms. My VTB-1 pre has settings of 50& *200. They do that just to confuse you. The microphone probably has an output impedance of somewhere around 250 ohms. As far as the preamp goes, the specs read: Mic Input (Rear switch in 200 ohm position): 2000 ohms Mic Input (Rear switch in 50 ohm position): 300 ohms Now how is anyone supposed to make sense of that? You anticipated my next question on that very point. |
#9
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Question about impedance matching mic & pre
On Thu, 8 Dec 2011 01:06:33 -0500, muzician21 wrote
(in article ): On Dec 7, 8:31*pm, Mike Rivers wrote: On 12/7/2011 11:12 AM, muzician21 wrote: Just got an MXL R40 ribbon mic. Never had a ribbon before. I see the mic specs say 250 ohms. My VTB-1 pre has settings of 50& *200. They do that just to confuse you. The microphone probably has an output impedance of somewhere around 250 ohms. As far as the preamp goes, the specs read: Mic Input (Rear switch in 200 ohm position): 2000 ohms Mic Input (Rear switch in 50 ohm position): 300 ohms Now how is anyone supposed to make sense of that? You anticipated my next question on that very point. They obviously need better writers,,,,,, Ty Ford --Audio Equipment Reviews Audio Production Services Acting and Voiceover Demos http://www.tyford.com Guitar player?:http://www.youtube.com/watch?v=yWaPRHMGhGA |
#10
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Question about impedance matching mic & pre
muzician21 wrote:
Just got an MXL R40 ribbon mic. Never had a ribbon before. I see the mic specs say 250 ohms. My VTB-1 pre has settings of 50 & 200. The original RCA designs basically are designed to work into an infinitely high impedance. You can present them with a lower than open circuit impedance but the lower it is, the more the top end is affected. Those MXLs are basically RCA copies, made by people who don't really understand the physics or how to make high ratio transformers, so I would expect the loading problems to be similar or worse. So use the highest impedance you can get. The odds are the "200 ohm" setting on the VTB-1 is an impedance of a couple kiloohms, designed for mikes with a 200 ohm output impedance. You really want more than that for a ribbon if you want good top end detail, but try it and listen and see for yourself. I'm not versed in electronics, does this mean it's not optimally suited for this mic? I get sound out of it, I understand that a ribbon sounds much different than a condenser and needs more boost, I don't have a basis for comparison as to whether it sounds the way it's supposed to. Same effect that you get with an SM-57.... decrease the input impedance, you increase the current load on the mike, so the damping on the diaphragm is increased. It's like reducing the tension on a string or a drum head. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
#11
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Question about impedance matching mic & pre
On 12/8/2011 8:57 AM, Ty Ford wrote:
They obviously need better writers,,,,,, They know where to find me. Actually, what they need is better people to design the labels for the controls so people won't be confused. Or just leave the switch off entirely and sell the preamp for $5 less. You have more mileage than I do so you may have encountered more mics that really sound better with a low impedance load, but I've only had one here that did, a CAD Trion ribbon which sounded flabby (best word I could use to describe it) on the low end until I switched the Mackie 800R to 300 ohms. Then it cleaned up nicely. I don't know why any preamp manufacturers looking for a gimmick haven't included an "SM-57" switch with a 600 ohm load that Paul Stamler wrote about several years back. But they all seem to skip over that number. -- "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 http://mikeriversaudio.wordpress.com - useful and interesting audio stuff |
#12
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Question about impedance matching mic & pre
On Dec 9, 7:05*am, Mike Rivers wrote:
On 12/8/2011 8:57 AM, Ty Ford wrote: They obviously need better writers,,,,,, They know where to find me. Actually, what they need is better people to design the labels for the controls so people won't be confused. Or just leave the switch off entirely and sell the preamp for $5 less. You have more mileage than I do so you may have encountered more mics that really sound better with a low impedance load, but I've only had one here that did, a CAD Trion ribbon which sounded flabby (best word I could use to describe it) on the low end until I switched the Mackie 800R to 300 ohms. Then it cleaned up nicely. I don't know why any preamp manufacturers looking for a gimmick haven't included an "SM-57" switch with a 600 ohm load that Paul Stamler wrote about several years back. But they all seem to skip over that number. I think Presonus had it on the ADL-600 preamp that Anthony De Maria designed for them several years ago. But the input impedances were actually different from what the labels said. By the way, Mike, I had the occasion to transfer a recording you did from LP to the computer and thence toCD a couple of days ago -- Mike Seeger's "New Freedom March". Going to play it on the radio on New Year's Day. Nice tune, nice recording! Peace, Paul |
#13
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Question about impedance matching mic & pre
Mike Rivers wrote:
On 12/8/2011 8:57 AM, Ty Ford wrote: They obviously need better writers,,,,,, They know where to find me. Actually, what they need is better people to design the labels for the controls so people won't be confused. Or just leave the switch off entirely and sell the preamp for $5 less. You have more mileage than I do so you may have encountered more mics that really sound better with a low impedance load, but I've only had one here that did, a CAD Trion ribbon which sounded flabby (best word I could use to describe it) on the low end until I switched the Mackie 800R to 300 ohms. Then it cleaned up nicely. I don't know why any preamp manufacturers looking for a gimmick haven't included an "SM-57" switch with a 600 ohm load that Paul Stamler wrote about several years back. But they all seem to skip over that number. McQuilken built a touch of inductance into the RNP to mimic iron inputs just so it would work well with the 57 and the 58. -- shut up and play your guitar * http://hankalrich.com/ http://www.youtube.com/walkinaymusic http://www.sonicbids.com/HankandShaidri .. |
#14
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Question about impedance matching mic & pre
Mike Rivers wrote:
I don't know why any preamp manufacturers looking for a gimmick haven't included an "SM-57" switch with a 600 ohm load that Paul Stamler wrote about several years back. But they all seem to skip over that number. It is an oooooooooold microphone, just like the B&O's and RCA's I've just been reading about how to deploy (Thanks Adrian!) and thus supposed to "go legacy". But perhaps asking them to label it a "legacy" switch would be better spin? Kind regards Peter Larsen |
#15
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Question about impedance matching mic & pre
"Peter Larsen" wrote:
Mike Rivers wrote: I don't know why any preamp manufacturers looking for a gimmick haven't included an "SM-57" switch with a 600 ohm load that Paul Stamler wrote about several years back. But they all seem to skip over that number. It is an oooooooooold microphone, just like the B&O's and RCA's I've just been reading about how to deploy (Thanks Adrian!) and thus supposed to "go legacy". But perhaps asking them to label it a "legacy" switch would be better spin? Kind regards Peter Larsen I've tried to remain on the sidelines for this thread. I thought it had run its course, but no. "Legacy"? I think Scott Dorsey made it clear that "oooooooooold" mics expected *NO* loading. When I climbed on the Audio Systems Engineering bus the rule of thumb for preamp input impedances was "2K ohm, or greater". As far as I can determine, that rule continues to be valid today. Yes, the inductive impedance of transformer-coupled inputs can modify performance in mysterious ways, but all-in-all, the rule stands. The real problem here is a matter of words. Many published input impedances are "Nominal". That means "Named"! *Actual* impedances tend to be on the order of "times ten, or greater", the standard rule for "bridging" A.K.A. "non-loading". It pushes me over the edge to see that preamp makers are offering choices. Oh, yeah, the SM57 sounds better with Paul Stamler's "gimmick" 600 ohm load. That's because it is a mediocre mic that became successful largely because it made an average PA system (with a 2K or greater input impedance) sound a little better. Decades later we have learned that it really is not a very good tool, and that there are many better choices in the same price range. Why, oh why, can't we overcome this "Legacy" problem and, instead, choose the best that modern technology has to offer? Good grief! Aren't we using Pro Tools because of the magic it delivers? Must we celebrate "Legacy" by going back to using non-magnetic surgical scissors for cutting paper-backed audio tape? I know I'll take some flack from some readers. Shrug. I made my living using my own brain to figure out what works best, not playing "monkey see, monkey do" or using inferior "Legacy" tools when there were far better modern choices. Bring it on! -- ~ Roy "If you notice the sound, it's wrong!" |
#16
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Question about impedance matching mic & pre
Roy W. Rising wrote:
[...] I've tried to remain on the sidelines for this thread. I thought it had run its course, but no. "Legacy"? I think Scott Dorsey made it clear that "oooooooooold" mics expected *NO* loading. It is clear from all the literature published at the time, that most old designs of microphone only gave their intended performance when they were correctly loaded. I am not referring to sales literature, I am talking about the research papers published by the designers of those microphones. Good quality mixing desks, in some cases, had tapped input transformers to allow a range of different microphones to be use. In other cases, such as the BBC, the types of microphone were standardised to one particular impedance value and the mixers were designed accordingly. When a 'foreign' mic had to be used, a separate matching transformer was interposed to match it to the 'standard' impedance of the studio. It was an expensive business, but it was necessary in order to meet specification. In those days it was far easier and cheaper to obtain really high input impedances, straight into the grid of the first valve, than to use a matching transformer. So if the no-loading approach had worked, they certainly wouldn't have bothered with the bulk and expense of transformers. [...] Why, oh why, can't we overcome this "Legacy" problem and, instead, choose the best that modern technology has to offer? One of the better aspects of 'legacy' technology was the necessity to understand what you were doing in order to use it at all. Modern technology does not need a deeper understanding of what you are doing. It gives better average results with less effort in an average situation when used by an average person. (It does not help much in a difficult situation unless it is backed by good fundamental understanding of the relevant disciplines: physics, electronics etc.). It works even better in skilled hands and can can give phenomenally accurate results, far better than anything legacy equipment offered, if that is what you want. Legacy equipment used properly by a skilled operator can also give excellent results, but it take a bit more effort on the part of the user. Sometimes it's shortcomings can actually be turned to advantage to produce a pleasing sound quality which is lost with 'better' equipment. However, legacy equipment used as part of a cult by the unskilled or technologically-ignorant operator gives the worst of all worlds. I think it is that aspect of 'Legacy' which gives it a bad name. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk |
#17
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Question about impedance matching mic & pre
Mike Rivers wrote: I don't know why any preamp manufacturers looking for a gimmick haven't included an "SM-57" switch with a 600 ohm load that Paul Stamler wrote about several years back. "Peter wrote: It is an oooooooooold microphone, just like the B&O's and RCA's I've just been reading about how to deploy (Thanks Adrian!) and thus supposed to "go legacy". But perhaps asking them to label it a "legacy" switch would be better spin? On 12/18/2011 8:43 PM, Roy W. Rising wrote: I've tried to remain on the sidelines for this thread. I thought it had run its course, but no. "Legacy"? I think Scott Dorsey made it clear that "oooooooooold" mics expected *NO* loading. I hardly consider the SM57 a "legacy" microphone, though I exoect that Shure would be proud of that designation. It's still a very popular mic, both among old and new users. RCA "legacy" ribbons indeed work best into a high impedance load but most of today's preamps that provide a choice of input impedance rarely go above 3k Ohms, but often go as low as 500 or even 300 Ohms based on the "ribbon mics are very low impedance" myth (which is true for the element, but not of the microphone). When I climbed on the Audio Systems Engineering bus the rule of thumb for preamp input impedances was "2K ohm, or greater". As far as I can determine, that rule continues to be valid today. Yes, it does. I've run across some preamps in the past year that have a (fixed) input impedance around 5k Ohms. This tends to sound pretty good with modern transformerless condenser mics and puts the preamp and mic on a pretty even price-and-quality match. It's probably a good choice for someone who is going out to the music store today to equip his first studio. But it may not be such a great choice for someone who has been acquiring mics over a 25 year period and has the itch to buy a new preamp. The real problem here is a matter of words. Many published input impedances are "Nominal". That means "Named"! *Actual* impedances tend to be on the order of "times ten, or greater", the standard rule for "bridging" A.K.A. "non-loading". This is indeed something that confuses newcomers. Some mic manufacturers swing both ways and state something like "Impedance 200 Ohms, suitable for preamps with an input impedance of 2000 ohms." Most, but not all, preamp manufacturers usually just specify the input impedance. Oh, yeah, the SM57 sounds better with Paul Stamler's "gimmick" 600 ohm load. That's because it is a mediocre mic that became successful largely because it made an average PA system (with a 2K or greater input impedance) sound a little better. Decades later we have learned that it really is not a very good tool, and that there are many better choices in the same price range. Who's this "we?" While today I would advise someone setting up a home studio fir the first time to look further than an SM57 for his first mic, I'd suggest that a band putting together their first PA system get a couple of SM57s because they're just so useful. But, on the other hand, you don't usually look at the impedance of the mic inputs on a PA mixer. Why, oh why, can't we overcome this "Legacy" problem and, instead, choose the best that modern technology has to offer? Good grief! What "Legacy" problem? Aren't we using Pro Tools because of the magic it delivers? We who? What magic? I don't use Pro Tools. I don't believe in magic when it comes to audio or software. Sure, I appreciate editing on a computer rather than with a razor blade, and hard drives save money over magnetic tape. But that's not magic, it's progress. Pro Tools is rapidly becoming the SM57 of DAWs. Let the clamor begin! -- "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 http://mikeriversaudio.wordpress.com - useful and interesting audio stuff |
#18
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Question about impedance matching mic & pre
Adrian Tuddenham wrote:
Legacy equipment used properly by a skilled operator can also give excellent results, but it take a bit more effort on the part of the user. Sometimes it's shortcomings can actually be turned to advantage to produce a pleasing sound quality which is lost with 'better' equipment. However, legacy equipment used as part of a cult by the unskilled or technologically-ignorant operator gives the worst of all worlds. I think it is that aspect of 'Legacy' which gives it a bad name. Spot on, Adrian. Ignorance may be bliss, right up until it plugs an SM58 into a Mackie 1202. -- shut up and play your guitar * http://hankalrich.com/ http://www.youtube.com/walkinaymusic http://www.sonicbids.com/HankandShaidri |
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