Amplifying Acoustic Instruments
June 9, 2015 2:18 PM   Subscribe

After ten years in a punk rock band, I'm now in an acoustic group. I have questions on using amps vs. PA, micing instruments vs. after market pickups, and what good quality, low cost options there are for amplifying acoustic instruments.

1. What experiences have you had using an amplifier vs. going straight through the PA? I've tried it both ways at practice and I'm leaning towards an amp just because it sounds more like what I am used to. It's feels weird to have the sound not coming from behind you, but I'm sure I could get used to it if there are advantages to using the PA.
2. Any recommendations for a good acoustic amp (preferably below $500 new)?
3. I have a couple guitars without pickups I'd like to use, but have had real problems with feedback using a mic. Any tips to reduce that, or would it be better to go ahead and buy after market pickups for them?
4. If I go with pickups, how do magnetic ones sound? They seem more common, but wouldn't it sound more electric than acoustic? are any of the cheaper piezo or transducer options any good?

Any general advice or resources would also be appreciated - our first show is in two weeks!
posted by InfidelZombie to Media & Arts (9 answers total) 3 users marked this as a favorite
I work sound for small live shows (2-5 people in the band, 50-100 people in the "audience") about once a month, so I'll happily defer to anyone with real audio engineering credentials.

Most guitarists I've worked with either wanted a mic or gave me a direct input from their pickups. I think so far I've only had two people (both bassists, not guitarists) bring their own amps. Personally, I prefer either to mike the guitar myself or to take a direct input, because having someone else running his own monitor on my stage just makes my mixing that much harder.

The sound crew should be able to mike your guitar without feedback. That's a pretty basic part of their jobs.
posted by d. z. wang at 4:44 PM on June 9, 2015

Re #2: I have a Roland AC 60 acoustic amp and I've been very happy with it. It also has balanced outputs to go straight into a PA, so it's like the best of both worlds.
posted by monospace at 4:57 PM on June 9, 2015

While a small amp can be a big help in certain situations, it's also worth considering the overall sound of the group. If you have a nice balance when you play together acoustically, you might not want to mess with that. Ideally, your stage sound should be as pleasing and comfortable as your rehearsal sound. Rarely happens, though. I have a ZT Lunchbox Amp that I keep around for emergencies. It's pretty great.
posted by Jode at 6:04 PM on June 9, 2015

What size venue, quality of equipment, and caliber of sound person are you dealing with? If it's mostly small venues with low end gear and an inexperienced or indifferent sound person (or someone that sets it up and then leaves it for the evening), trying to mic it is likely to be an exercise in bad sound and feedback, so I'd recommend getting a good pickup and amp and using that so you have control over your tone on stage. Get something with a direct out so the amp can be supplemented in the FOH mix as needed. Unfortunately, my experience is mixing, so I don't know what brands of pickups to recommend. I've definitely seen a lot of the Roland acoustic amps out there.

If you're working with someone that will pay attention to the mix and knows how to work with miced guitars, one thing that can work well is using a pickup for the monitor mix and a mic for FOH (possibly supplemented with some of the pickup). I've very successfully used the $200-500 vocal super/hypercardiod condenser mics from Shure, Sennheiser, and Neumann on acoustic guitars without pickups, using the tight patterns to get good gain before feedback, even when using the mic in the monitors as well.

On the cheaper end, some of the MXL pencil mics don't suck, but their quality is uneven so it's hard to know what you're going to end up with, and live sound is less forgiving of uneven response than recording.

Part of the problem with using the amp as the primary source for your guitar sound rather than the PA speakers is the height - your amp is likely to be at a lower height than the PA speakers, which will make the guitar sound worse in the back. Again, given a good sound person, one thing to consider is using the amp on the ground tilted up facing you as your guitar monitor, so that most of the FOH mix comes from the PA speakers.
posted by Candleman at 6:23 PM on June 9, 2015 [1 favorite]

Depending on what sound you're going for, you might consider getting one guitar with a good pickup and get some processing units to get different tones out of it rather than trying to get good sound out of several guitars with cheap pickups.

Also, if you're not used to performing with a miced guitar, be really careful about moving around on stage and swinging the guitar into the mic. The audience's ears and the sound person's sanity will thank you.
posted by Candleman at 9:28 PM on June 9, 2015

The sound crew should be able to mike your guitar without feedback. That's a pretty basic part of their jobs.

Yeah, in theory. In the actual Real World, "should" takes a back seat to "is", which includes where the main PA system is placed in relation to the stage, what speakers I'm actually using as the PA (mains and monitors) and what their inherent audio characteristics are, what the capabilities of the mixing board are and whether or not I have any outboard gear, like graphic equalizers and compressors, the acoustics of the venue (including the stage), where the performer stands in relation to the monitors, how noisy the crowd is, the temperature, the humidity, how much time (if any) you have to check the bands' sounds, how well the performer knows how to actually play with some volume and how to "work" the mic, how loud anyone expects it to be. I'm dealing with 1001 variables plus laws of physics that may make it difficult to impossible to do what I "should" be able to do.

Oh, and if there's a drummer who plays with any volume? Congratulations, you've just added a second snare & cymbal mic.

I've been doing sound for a living for 20+ years, and "Uh, I don't have a pickup for my guitar" is one of my least favorite sentences.

I'll second Candleman in general, although just note that the context of the performance and space can have a big effect. I've gotten acceptable results out of your basic plain old $99 Shure SM 57 - when it's an act that's all acoustic string instruments, in situations where neither the audience nor the musicians are expecting AC/DC levels of volume and the audience is quiet and attentive. Even better if they actually know how to play.

If you're not in those kind of situations, a pickup is probably a more practical choice - whatever tonal qualities of the instrument that you like so much will be either inaudible or altered by the sound person simply in order to get some volume out of the PA.

1. What experiences have you had using an amplifier vs. going straight through the PA?

If you mean a regular ol' guitar amp, like a Fender Twin . . . . . meh. Electric guitar amps are pretty much built to emphasize mid-range frequencies that make acoustic guitars sound "boxy." Plus feedback out of the amp is a strong likelihood at common stage volumes. I'll deal with it but it's not my favorite. Acoustic amps are generally friendlier to acoustic instruments.

Although note that if you have a DI you can certainly do both amp and PA. Plug your guitar into the DI, there'll be a paralleled 1/4" output so you can run a cable to your amp, and the XLR output goes to the PA.

By far the most used DI I've seen for acoustic instruments is the L.R. Baggs Para Acoustic DI, which not only sounds pretty good on its own, but gives the player some tools to sculpt their tone and reduce feedback.

if there are advantages to using the PA.

Well, the main advantage would be that most PA speakers are less "mid-rangey" or "boxy" than most electric guitar amps, so your acoustic will sound more like an acoustic guitar "should." Also if you're playing a space large enough for a PA it's possible that there's no way to get your amp loud enough to cover the room without feeding back.

2. Any recommendations for a good acoustic amp (preferably below $500 new)?

I've heard good results out of various Fishman Loudboxes and Fender Acoustasonics, and while I don't think I've seen one in the wild, Roland has a line of acoustic amps, and they're generally known for good products - their keyboard amps are a staple in the business.

And I'm 99% sure all of these amps have an XLR output so you can use both the amps and the PA without needing an external DI.

3. I have a couple guitars without pickups I'd like to use, but have had real problems with feedback using a mic. Any tips to reduce that, or would it be better to go ahead and buy after market pickups for them?

As per my rant above, acoustics without pickups can be very very difficult to deal with. If you're running your own sound, it can help to have a Graphic EQ for your mains and each of your monitor sends (acoustics like to feed back around 125 Hz, and cutting some of the midrange between 500 Hz & 1kHz can also get you more volume before feedback.)

If you're playing gigs where you're at the mercy of whatever highly variable PA is provided and whatever highly variable skills the sound person (if there is one) may have . . . . . . get a pickup. Then you've at least got a fighting chance.

If I go with pickups, how do magnetic ones sound? They seem more common, but wouldn't it sound more electric than acoustic?

It's pretty variable - they all sound at least a little "more electric" than built-in under-saddle pickups (which can be added to a guitar, by the way, although I would have an experienced guitar tech/repair person do it rather than attempt a DIY), but some are not bad at all. My personal favorites are the various Fishman models (especially the Rare Earth series), and the L.R. Baggs M1 or M80.

are any of the cheaper piezo or transducer options any good?


Well, that is to say, I've never encountered a "transducer" - the little round thing that you stick on the body of an instrument - that's worth a damn.

"Piezo" usually means a thin strip of piezo-ceramic material that sits under the saddle of the guitar. This is what's actually used for acoustics that "have pickups", then the manufacturer adds a preamp to boost the signal level and shape the tone a little and possibly add volume and tone controls. Adding one to a guitar means doing some drilling, which, as above, I dunno that I'd attempt unless you've got some experience working on guitars.

Even if you add a piezo under-saddle to your guitar, they tend to have very low output, which means they're not much good in practice unless you also buy an external preamp, like the L.R. Baggs DI I linked above. So a magnetic soundhole pickup might actually be cheaper overall, since with almost all of them you can pretty much plug directly into any amp or DI box.
posted by soundguy99 at 9:42 PM on June 9, 2015 [2 favorites]

Oh yeah, and if you're gonna be plugging and unplugging guitars, take your pedal tuner from your days as an electric player, hook it up directly after your guitar, and use it as a "mute" switch. (And a tuner, of course.) Acoustic preamps built into the guitar and many magnetic pickups require power from batteries, and they're all wired up so that plugging a cable into the jack turns on the power. (Technical explanation is the second question here; the author is referring to guitar effects pedals, but the same principle applies to acoustic guitar jacks.)

In practice this means that when you plug and unplug your guitar, you will be making/breaking a DC power connection, which sends an incredibly loud "POP" down the cable. This will scare the bejeezus out of the citizens, annoy the soundperson, and can actually damage speakers. So you use your tuner to cut off the signal so you don't hear that "POP."
posted by soundguy99 at 6:11 AM on June 10, 2015

I was about to post "paging Soundguy99" then I got to the sig, and of course, it's himself. Heed him.

"Uh, I don't have a pickup for my guitar" is one of my least favorite sentences.

I've been at this on and off since the 1970s, and even so I think miccing an acoustic guitar in any non-concert setting is so oldschool it doesn't even count as school. There are so many good / inexpensive options that it's no longer a question of whether. The only situations I see guitars being micced anymore is open mic nights. I guess bluegrass bands don't like p/ups, but then I saw Newgrass Revival when Bela Fleck was still in it back in the 1980s and they were all using p/ups.

I used to get good results miccing and recording acoustic folk, Indian, and chamber instruments in small venues with attentive audiences. And you might get away with it as a solo act. (An SM57 or equivalent is just fine.) If you're an artiste sitting still on a stool with a little footrest not making eye contact with the audience and concerned with authenticity -- I'd recommend at least three mics.

But if there are other instruments, you'll want to use a pickup, if only to have some control of the mix. Also, unless your act is like Oregon or something, you're entertainment -- you're going to be moving around on-stage, making eye contact with your audience and cueing bandmates. So -- you won't be maintaining a consistent distance and angle with a mic. That's a formula for feedback and inconsistent sound. If, just as you're digging in for a nice run or riff, you back off from the mic -- either dramatically, unconciously, or just to give yourself some space -- you're the only one who's going to hear it. It's just a headache you don't need. Get a nice soundhole mag p/up for your existing axe and get out there.

As to amps, I've been using a Roland AC-60 for years with good results. The AC-60 is now part of a whole line of Roland acoustic amps with similar characteristics, from the battery powered 30-watt AC-33 to the 90-watt AC-90. I believe they all have XLR direct output, giving you the flexibility to provide DI to the house, while allowing yourself a little (or no) monitor. If there's no house, you can plug a mic in to the AC and you're your own PA.

Keep in mind, as Soundguy99 says, these are full-range amps (class A) -- very different circuits from electic guitar amps (class C). Differences, apart from the freq response: First, turning up too much gives you only bad distortion never good distortion. There's no cool secondary benefits from having too small an amp. Second, when shopping, you can't compare power output apples-to-apples with electric guitar amps. A 200w class C tube amp would be insanely loud -- Hendrix/Townsend loud. A 200w class A amp, turned up, will fill a nice sized room with clean full range sound.

O, brave new world, that has such technology in't.
posted by Herodios at 7:11 AM on June 10, 2015 [2 favorites]

The show went well on Saturday, so thanks for everyone here for the advice, it was very helpful. Ended up playing through the PA and spent my money on a classical guitar with built in pickups instead of buying a cheap pup for the one I had. I'm sure I'll end up getting an amp soon, if for no other reason than to have the flexibility available since I don't really know what sorts of venues we'll end up playing at. First we have to write more songs!
posted by InfidelZombie at 2:18 PM on June 24, 2015

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