Topic: Quick questions about dynamic mics

[vantheman]

Hi all, took a spin around some threads but didn’t find what I’m looking forward to. I’m recording a trio from stage lip and need to mic the bassist’s amp. Picking up a SM57 has been on my list for some time, and that time has come. But I have no experience whatsoever with dynamic mics and want to make sure I’m not screwing anything up - heard horror stories about ribbon mics frying, etc.

Two pieces of gear I’ll be using to record - Sound Devices MixPre6 and Tascam DR100mkiii. The former just has a wide range of gain you can give a mic, and the Tascam does as well but also has a pad switch for quick attenuation. Can I fry a Shure SM57, or is it just a matter of dialing in the gain the same way I would with a condenser? Would I generally want pad off in loud show environment with a close-miked bass amp?

[fireonshakedwnstreet]

You can mic a jet engine with this thing. It has very low sensitivity (-56 dbv) and can take up 151 spl. Turn off phantom, plug it in and crank the gain.

[vantheman]

Music to my ears. Thank you!

[rocksuitcase]

You can mic a jet engine with this thing. It has very low sensitivity (-56 dbv) and can take up 151 spl. Turn off phantom, plug it in and crank the gain.

Yes, the base line difference between dynamic mics and condensers is dynamic mics do not require phantom power.

[morst]

And the difference between dynamic mics and ribbon mics is that phantom power will not hurt dynamic mics.
It will damage most ribbon mics. But you don’t have to worry about that.


You will find the different parts of the speaker resulting in different tones. The very center of a JBL speaker typically has a lot more high frequencies. Like too much. Do not mic the dust cap on a JBL unless you need brightness.
Conversely, the outer edge of most speakers is often lacking in treble, so I usually start by aiming at the middle of one side of the cone, if that makes sense.
I would suggest starting with the pad off, unless you find that it’s necessary

[goodcooker]

There is more than one way to skin this cat. Lots of bass amps have a DI output which can send a line level signal directly to your recorder. If you have the available inputs and cables it wouldn't hurt to use it - it can bring a lot of clarity by bringing detail and harmonics but is lacking in real low end of the registers if used alone IME. Mixed with a dynamic mic like the SM57, used off center of the bass cabinet largest speaker and utilizing proximity effect, it makes for the best sound that mixes well.

Other mics I've used on bass cabinets with great success are the Sennheiser e609 (usually used on guitar amps) and the AT2020 condenser. Having a SM57 is great idea though. You can use it for all sorts of things and works as a hammer in a pinch.

[morst]

There is more than one way to skin this cat. Lots of bass amps have a DI output which can send a line level signal directly to your recorder. If you have the available inputs and cables it wouldn't hurt to use it - it can bring a lot of clarity by bringing detail and harmonics but is lacking in real low end of the registers if used alone IME. Mixed with a dynamic mic like the SM57, used off center of the bass cabinet largest speaker and utilizing proximity effect, it makes for the best sound that mixes well.

Other mics I've used on bass cabinets with great success are the Sennheiser e609 (usually used on guitar amps) and the AT2020 condenser. Having a SM57 is great idea though. You can use it for all sorts of things and works as a hammer in a pinch.

Good point, though if you are already recording a board feed, the isolated bass direct line may be of less value. Doesn't really sound like that's the case here.
In fact, if there is a PA system, the direct output is likely already used, though some units have multiple outs.


57 as a hammer? Obviously use the plug end, that plastic cap will break right off!

[vantheman]

There is more than one way to skin this cat. Lots of bass amps have a DI output which can send a line level signal directly to your recorder. If you have the available inputs and cables it wouldn't hurt to use it - it can bring a lot of clarity by bringing detail and harmonics but is lacking in real low end of the registers if used alone IME. Mixed with a dynamic mic like the SM57, used off center of the bass cabinet largest speaker and utilizing proximity effect, it makes for the best sound that mixes well.

Other mics I've used on bass cabinets with great success are the Sennheiser e609 (usually used on guitar amps) and the AT2020 condenser. Having a SM57 is great idea though. You can use it for all sorts of things and works as a hammer in a pinch.

I had no idea what a DI was until a few days ago, but the bassist uses gut strings on his upright which apparently sounds bad through a DI but fine once routed through the amp. I have no frame of reference for this but I certainly take his word for it. I got a great deal on a Shure Beta 52a kick drum mic locally, so I think we might run that and a SM57 and take the better of the two or mix them. Should be interesting, but the main goal is to do justice to his sound.

[morst]

I had no idea what a DI was until a few days ago, but the bassist uses gut strings on his upright which apparently sounds bad through a DI but fine once routed through the amp. I have no frame of reference for this but I certainly take his word for it. I got a great deal on a Shure Beta 52a kick drum mic locally, so I think we might run that and a SM57 and take the better of the two or mix them. Should be interesting, but the main goal is to do justice to his sound.

DI is short for "direct injection" which is just a way of saying direct signal feed, colloquially referred to as a DI box when it is separate.
There are two places in the signal path where one might place the DI.
The first place is to split the raw signal from whatever pickup, or contact mic is coming from the instrument.
The "guitar cable" from the instrument is plugged into the DI box, and then that feeds the player's own stage amp rig, as well as the PA system.
The second place to take a direct feed would be to take the direct signal out of the instrument preamplifier, probably a duplicate of the signal which is sent to the power stage and speakers of the bass (or other instrument) amp.
Most modern pro bass amps, especially head units (just the preamp and amp, no speaker built into this part) will be equipped with an XLR and/or a 1/4" direct output jack, usually on the back of the box.
The local PA system will usually take whichever of the two is most applicable to their circumstance... (leaving the other for the stage recordist!?)
But this operation is contingent on a line signal of some sort.
Most electric basses have one or more magnetic coil type pickups, but these rely on the the physics of a metal string oscillating near the coil.
Now we learn that this particular bassist doesn't play with steel strings.
So much for pickups.
But in order to use an amp, there must be some sort of signal coming down the cable, and the amp must make something good from it.
There are ways to pick up sound from non-metallic strings, but they are acoustic in nature, rather than the electromagnetic pickup method of a single or double coil ("hum bucking") pickup.

If you have a free channel on which to record, it may be instructive to capture the dry signal from the DI.
Going by the real-world experience of the folks who know the gear, don't expect to rely on it for best audio quality...

I hope this info is helpful and not overly obvious or superfluous/off topic

[DSatz]

rocksuitcase wrote:
> the base line difference between dynamic mics and condensers is dynamic mics do not require phantom power.

Yes.

But also: Most condenser microphones are much more sensitive than most dynamic mikes--condensers typically put out 12 - 15 - as much as 20 dB more signal for a given sound pressure level. This can be a good thing if the preamp / recorder / mixer is easily overloaded; dynamic microphones put less stress on the inputs. But it's a far less good thing in the presence of RF or magnetic fields.

And finally, moving coil microphones (the type of dynamic mike most people here are talking about) on average are less physically fragile than condenser mikes are on average. The exceptions are mostly ribbon microphones (= a type of dynamic microphone).

Yes, you should switch off phantom power before connecting any dynamic mike to a recorder / mixer / preamp input. In principle, phantom powering will not harm any correctly wired dynamic microphone provided that the cable is also correctly wired as a balanced line. But accidents do happen, and they tend (a) to occur, as Murphy's Law dictates, at the worst possible moment (just when you were about to record something) and they also tend (b) to necessitate the most expensive repair that a dynamic mike can ever require, the replacement of its element (ribbon or moving coil system). So it's safest to pretend that phantom powering is potentially harmful to dynamic mikes even though, as I said, in principle it isn't, and usually in practice it isn't, either.

--best regards

P.S.: When I started recording in the early 1970s, condenser mikes were very expensive, and rather difficult for individuals to obtain. The better dynamic microphones (e.g. from Beyer and Sennheiser) still had well-earned reputations for good sound quality, and I think they are sometimes undervalued today. That said, the price difference between good dynamics and decent condensers has come down to zero or less in the intervening decades, and I can't think of any circumstances in which I would purposely choose a dynamic mike over a condenser, unless I knew that the microphone was likely to be physically damaged, e.g. thrown around or hit against things.