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Mics For Amp Cabinets & Their Sensitivity Spec?

Discussion in 'Ampage Area' started by GarethJWilliams79, Aug 3, 2018.

  1. I’m looking into mics to mic a guitar amp, and trying to compare the sensitivity. I’ve googled this and tried to find out on TY videos but I can’t work out what is more sensitive a low number or a high number (of mV/Pa). So the ones I am looking at are Shure SM57 which is 1.60mV/Pa and Sennheiser e609 Silver which is 1.5mV/Pa. Which is the most sensitive?

    I thought this might be important because I don’t play my amp really load. I use a Vox AC30C2 and I play with the volume so it’s only about 30% up on both master volume and normal volume knobs with clean and distorted parts. So I figured the more sensitive mic would be better as I’m not really maxing out volume. Does that make any sense? or doesn’t it really matter how loud you have your amp when you are choosing a mic?

    Thanks for your help,
    Gareth
     
  2. stevo

    stevo Country Gent

    May 1, 2012
    Atlanta
    Sensitivity isn't as important for micing amps as isolation, hum cancellation and sound pressure handling. Smaller diaphragms and dynamics are preferred because of less off-axis coloration and greater ability to handle the head-on sound pressure. SM57 is plenty fine most of the time. e609 is designed for amps by having a super cardioid pattern which provides great isolation and hum cancellation which is nice for situations like live stage.

    And even with all that, we mic our Vibrolux Reverb 2x10 with a Røde M5 small diaphragm condenser. It's accurate, has little to no bleed-in from other instruments and was already on hand.

    Between the Shure and Sennheiser, keep in mind that the Shure is a great all around mic that you can use for just about anything. The Sennheiser is designed specifically for guitar amps, so it will be hard to press it into use anywhere else.

    Also, the Max SPL on the SM57 is 180 db which is 20 db higher than the e609. But keep in mind, 180 db is like the space shuttle liftoff from 100 feet away. 160 db isn't perceptibly different. So either can take everything you'll throw at them.
     
    Last edited: Aug 3, 2018
  3. T Bone

    T Bone Country Gent

    I like the versatility of the SM57, also very good for vocals, yet highly respected and often used for micing amps.

    You didn't mention if this is for a live sound situation, or for recording. I suspect some mics are better for one or the other, but I'm no expert. Still hard to go wrong with the SM57.
     
    Sid Nitzerglobin likes this.
  4. Thanks guys. The one I'm leaning towards is the Shure because they have that in my local PMT store so I can go in and get it. I still would like to know if higher or lower mV/Pa is more sensitive. I'm a bit baffled by this because I've got two Sennhieser dynamic vocal mics, e845 (1.8mV/Pa) which was £99.99 and e835 (2.7mV/Pa) which was £83.00. If the higher number is more sensitive then the less sensitive one is more expensive which doesn't make much sense! I never use the e835, it's still in the box so I haven't compared them by ear.
     
  5. stevo

    stevo Country Gent

    May 1, 2012
    Atlanta
    Higher is more sensitive. It's saying how much signal you will get from a known standard signal.

    As for tracking cost vs. sensitivity, that's a futile effort as sensitivity is only one of many parameters that impacts the cost of a mic.
     
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  6. Sid Nitzerglobin

    Sid Nitzerglobin Country Gent

    Jun 8, 2015
    fROMOHIO
    I'd say volume matters when you're using large diaphram condensers and ribbon mics, you can generally blow those pretty easily if you don't maintain some distance. Dynamics are a lot more rugged in general and as a default I would have very little concern slamming those right up on the grill of a dimed 100w Super Lead > a 4x12. Stevo is spot on that the SPL limit is the spec to look at if you're wanting to compare the ability to handle volume.

    An SM-57 + Sennheiser MD421 was the go to combo for guitar cab micing 75-80% of the time for me and most of the other engineers I worked w/. I liked my EV RE-27 subbed in for the 421 for some sounds as well. Maybe a condenser a few feet back from the cab if we were looking for some organic ambience/dimension.

    If you don't have an SM-57, definitely grab one. They're built like tanks (or they were in the 90s any way) and are pretty damn versatile.

    This is all talking about a recording context rather than live...
     
    Last edited: Aug 3, 2018
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  7. LivingMyDream

    LivingMyDream Country Gent

    Hi Gareth, welcome to Gretsch-Talk!

    Honestly, the values for sensitivity of the 2 mics is so close, I don't think you'd notice much of a difference. For me, the important factor would be how versatile I wanted the mic to be. If I wanted more versatility, it would have to be the SM-57, but if I had some other mics to handle various things, then I'd go with the e609 as a dedicated cab mic.
     
  8. wabash slim

    wabash slim Friend of Fred

    Age:
    68
    Feb 10, 2010
    lafayette in
    Best bang for the buck---SM57. Nothing wrong with the Sennheiser, either, but the Shure is far more useful in many applications.
     
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  9. Thanks for all your help guys. Sid Nitzerglobin, actually it is for playing live not for studio recording, to mic the amp into the PA. It sounds like either would do a good job but the Shure I think is looking more likely at the moment.
     
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  10. Sid Nitzerglobin

    Sid Nitzerglobin Country Gent

    Jun 8, 2015
    fROMOHIO
    Ah, yeah I should have connected the dots that this was for live use.

    For live, I'd be looking at the pickup pattern (and most of the time SPL max, but you say you're generally keeping things pretty quiet so probably not a big concern if you're sticking w/ dynamics) . The narrower the the pattern, the better the mic will be at rejecting off axis signals which helps limit bleed and feedback potential. It also makes placement and orientation of the mic a bit more critical/finicky to getting the sound you're looking for. Sensitivity on specs sheet always seemed like one of the least consistent measurements between manufacturers and you can usually make up for any difference at the mic preamps. IME, high sensitivity seemed to be more of an asset w/ acoustic instruments/vocals/room mics/overheads in the studio, high sensitivity seemed like it could be more of a liability live in my more limited experience there, but ???

    Unfortunately the best judge is usually to try the options out w/ your stuff and let your ears decide IMO. Bearing this in mind I think the SM-57 is probably a safer bet as they usually sound at least pretty good on guitars and most other sources you might want to mic up to boot.
     
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  11. stevo

    stevo Country Gent

    May 1, 2012
    Atlanta
    That would be wise. If you don't already have an SM57, it's a no brainer.
     
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  12. Freshy

    Freshy Gretschie

    267
    Sep 30, 2017
    Homosassa FLA
    Always liked the 609 as the best sounding and the fact that you could keep 1 less boom on the studio was a plus too. Technically though I got nutin.
     
  13. If I got that I'd get a boom anyway (mini one) because I don't like the idea of not being able to vary and experiment with the distance from the cabinet. It also wouldn't hang over my amp without something to clip the cable to the handle, as the handle is a pretty ridged semi circle not something that would grip down on a cable and hold it, and it wouldn't hang over the right spot as I have two speaker cones (one at each side of the cab) and the handle is in the middle. Basically I'd need a boom for the e609 anyway!
     
  14. stevo

    stevo Country Gent

    May 1, 2012
    Atlanta
    You'll want to mic directly over just one of the speakers - experiment with axis placement as well as relative distance which shouldn't be very far away.
     
  15. I’ve ordered the Shure SM57 but run into a problem with getting a mini stand to go with it! I should get the Shure tomorrow so I’ll know by then anyway, but does anybody know what size screw the Shure SM57 mic holder has? My Sennhieser holders have a smaller thread that don’t fit on my Quik Lok mic stand. Instead I have a XCG microphone clip on my Quik Lok stand.

    I don’t understand the logic to this because both are European. I think they have different sizes in the US, but the Sennhieser is German and the Quik Lok stand Italian so I don’t see why the two don’t fit together. Further more it doesn’t ever tell you the screw size on the mic stands so you have to go by the picture which is a bit risky. This is a bit annoying! I don’t want to get a stand that doesn’t fit the mic holder and have to send it back! :-(
     
  16. Floo

    Floo Country Gent

    Dec 16, 2012
    Elmshorn, Germany
    There should be a threaded adaptor in the Sennheiser holder. When you unscrew it, the holder should fit the bigger thread from the stand.
     
  17. wabash slim

    wabash slim Friend of Fred

    Age:
    68
    Feb 10, 2010
    lafayette in
    5/8"-27 is mike stand standard thread size. You can easily use a desk stand. Also, you can mike a speaker from the rear. You only have to mike one speaker as well. Either one should sound the same.
     
  18. Thanks Floo, I think you're right. There is another thread size in the Sennheiser holder if I unscrew the smaller one. Like Russian dolls! It looks like it can be taken out with a large screwdriver to reveil a larger 5/8" thread. I have ordered a König & Meyer 25935 mini stand. I'm not sure what size screw it has yet, it looks like the smaller 3/8" size but either way I should be Ok. Thanks for your help. Wabash, mic the back of the amp! That's a bit unorthodox isn't it!
     
    Floo likes this.
  19. Sid Nitzerglobin

    Sid Nitzerglobin Country Gent

    Jun 8, 2015
    fROMOHIO
    For open back cabs, the back is where the tonez live sometimes ;)
     
  20. Scott Fraser

    Scott Fraser Country Gent

    Jan 14, 2012
    Los Angeles
    I've been a pro recording & live sound engineer for 45 years & I can tell you that absolutely nobody in the business cares about mic sensitivity for miking a guitar amp. We only care about how the mic sounds. Does the sound coming out of the PA system sound like what you want or not. Personally I'm not a fan of the 57 on guitar amps, I prefer various Sennheisers & always choose an MD421 or MD409 when I'm bringing my own mics to a gig, but I've used plenty of 57s in plenty of venues & they work just fine. My preference is for the Sennheiser but I can get the job done with either one.