Who can explain amplification to me?

[Jordan S.]

My experience with plugging in instruments is confined to routinely connecting my Stratocaster to my Fender amp as a 15 year old Nirvana fan, turning the volume to 10, and blasting out power chords until the police showed up.

Now, I'm no longer 15, and I'm looking for some help understanding the process of amplifying my mandolin in a more, well, refined way. I.E. What's a preamp and how does it work? What are the various setup options? What works well/what doesn't? Different types of pickups? That type of stuff...

[kkmm]

Seem to be a simple question, but it's not. It takes quite a lot of life experiences with sound systems, combo amplifiers, preamps, effect boxes, etc... to have a good feel of what they will do to different types of pickups.
I have gone thru many types of pickups and finally settled down to: under the saddle pickup for guitars / mandolins / ukulele. These usually come with a preamp that need to be integrated in the instrument body (on the side). A multi effect box helps a lot in enhancing the sound (regardless of the amplifier it got plugged in, no effect in this case). It has to please my ears for me to play confidently loud for a large audience. If it sound bad, better not to play.
Acoustic electric guitars from GC is a perfect example of my preference (and remember, you get what you pay for).

[Nevin]

Most acoustic instruments use a piezo pickup if they are going to be plugged into anamplifier. The output from a piezo is very different from your old Stratocaster. There are two ways of dealing with this. There are amplifiers that are specificly made for acoustic instruments and handle a piezo level input just fine. If however you want to plug into your old Fender amp or the like you can have problems with what is called an impedence mis-match. This tends to give low volume and poor tone. The answer is to put the signal from the piezo pickup through a pre-amp that boosts the signal to the level the amplifier is designed for. Piezo pickups can give good sound and while feedback can be a problem, unless dealing with very high stage volumes they can be made to work.

Some people use contact microphones. These are essentaily microphones that use the instrument itself to act as the diagphram. Many of them are condesor microphones and require phantom power which can be supplied by a special pre-amp. Even when phantom power is not required, most require a pre-amp unless being used with an acouatic instrument amplifier (and some even then). Contat microphones can have very good sound but are more prone to feedback problems than piezo pickups.

Some mandolins are equiped with electromagnetic transducers which are the kind found in your old Sratocaster. They work fine with ampls like your old Fender amp but do not work well with acoustic amplifieers unless they have a dedicated imut for them. Electro magnetic transducers tend to sound the least like the acoustic instrument but they have a unique sound that some people like. They are the least prone to feedback but any amplified instrumetn can feedback.

[almeriastrings]

What is a preamp...

It takes a low level signal and makes it 'louder', in simple terms. For example, the very small voltage generated by a dynamic microphone. It amplifies this and greatly increases the voltage ready for passing along to the next stage in the chain, which is usually equalization ('tone controls'). There is quite a lot of confusion about this. Mixing desks have preamps built in, for example, designed for the microphones.... and as mentioned above, some instruments have active electronics, which also means they have a preamp built in. Some don't, though, and for these you may well need a separate, external preamp.

Preamps can do more than just adjust the level, though, one important function is to match the impedance (a kind of frequency dependent resistance) of the pickup or microphone to the input. This is a complex area, but microphones tend to need quite low input impedances, from a few hundred to a couple of thousand Ohms, magnetic pickups as used on electric guitars tend to need a few tens of thousands of Ohms, while piezo transducers as used on acoustic instruments may need anything from one to ten million Ohms. Big difference! If you have the wrong input impedance match it can cause various problems.... so it is a good idea to make sure the 'match' is about right.

One other function often built into preamps designed for instruments is some form of specialized EQ. Often a 'notch filter' and some EQ (tone controls) designed to help everything sound more natural and combat feedback.

So preamps can differ quite a lot. They go from built-in sub-miniature units in a guitar, to large rack mounted, tube powered things in studios... and can range in price from $10 to several thousand. It all comes down to what you need to do, and how well you need to do it.

[Bertram Henze]

I always found I understood that "impedance mismatch" thing easier when given a mechanical analogy:
Any oscillation has those two features: forces and paths, i.e. how hard is it to move the oscillating medium, and how long are the paths travelled back and forth by the medium's particles. Both multiplied always yield the energy contained in the oscillation. Thin media (e.g. air) have low forces and long paths, thick media (e.g. water) have high forces and short paths. This "thick/thin" difference is the mechanical counterpart of the electrical impedance mismatch. Sound travelling across a media boundary (e.g. air to water) will be split into a small portion that actually permeates the boundary and a big portion that's reflected (when you dive in a swimming pool, you'll hardly hear the merry chatter from the party above any more).
So what you need to to get the whole sound through the boundary is some lever contraption that turns small forces and long paths into big forces and short paths. One such contraption is those three tiny middle-ear bones that connect your eardrum to your cochlea. You middle ear is a mechanical impedance adapter (or, if you like, a preamp)

Just like that, electrical impedance is made up of high voltages and low currents (= high impedance) vs. low voltages and high currents (= low impedance), and different impedance components need adaptation accordingly.

Enough physics lecture for today.

[Atlanta Mando Mike]

It's pretty easy these days. I've had a lot of success using high quality acoustic amps that already have great preamps built in like The fishman loud box and the AER compact amps. I use a K&K twin pickup and plug it directly into the amp with a volume pedal or boost pedal for solos then run the amp directly to the sound system. If you want to use a preamp instead of an actual amp, 2 very popular preamps are the LR Baggs Venue DI and the Fire Eye Red Eye preamp. They booth sound good.

[Londy]

All I can tell you is, playing louder does not make you play better!

[Jordan S.]

This is all really helpful stuff, guys, thanks. I appreciate the technical explanations.

I understand there are essentially four components. The instrument, the pickup, the preamp and the amp. Or, I could skip the amp and plug right into a PA system if the situation dictated, I suppose?

Short of being able to actually test several different setups, is there a *generally* accepted setup or brands/models that are recommended if I'm doing my best to keep the instruments natural tone? I'm particularly curious about amps.

[Austin Bob]

To me, any discussion on amplification equipment should start with asking what kind of group you are playing with, and what is your typical venue.

There's a reason lots of string bands use condenser mics for the instruments; they provide the cleanest sound. But the pros are usually connected to a mixer with a sound person controlling the output, and there are stage monitors present so the performers can hear themselves in the mix.

I play in a choir, with a mix of two guitars, a flute, viola, and twelve or so voices. We have about 5 minutes to set up and do a sound check, so I use a K&K pickup and run it to a LR Baggs Venue pedal. This gives me a pre amp and volume switch for solos, and I can teak the output on the pedal to allow the settings on the mixer to be flat. It also is battery powered, which is important because we only have one power outlet and it is already overloaded.

When I play in coffee houses and the like, I use the same pickup and pedal, but run it through a Fishman loudbox.

There are trade off from pickups vs. mics. Pickups are easier to use and set up, but the output is not quite the same as from a good mic. Mics can be temperamental and it takes practice to stand in the right spot.

I use a condenser mic for the times when I want the cleanest sound, but for me, the K&K into the Venue pedal is my go to setup.

[Nevin]

There almosty as many combinations as there are mandolins. As Austin Bob said the choices are dependent on the kinds of vnues you are playing and the kind of music. Others who have far more experience than I do can give you more specific advice but here are some generalizations.

If you are just getting together with friends to jam or playing small coffee house type venus, unless everyone else is amplified, you probably don't need to be. I played a gig a few months back at a loud bar. I was only playing one tune on mandolin. There were two singers going through the PA an electric bass, and an amplified acoustic guitar. The soundman forgot to turn on the microphone for the mandolin. Apperently I came through just fine.

If you are playing somewhat louder or bigger venues, consider using a microphone. They tend to give you the sound closest to your mandolins acoustic sound, they are easy to transport and setup and can be relatively inexpensive. While many people would recomend a condensor microphone (and there are many threads talking about the various options in condensors) don't overlook the simple and inexpensive option of a dynamic mic like the Shure SM57. It does take some practice playing into a mic and your ability to move around the stage is limited.

When you play with other instruments that are amplified or other situations where the onstage volume creates problems with feedback it is time to look at pickups and amplifiers. There are many threads on the virtues of various combinations of pickups, pre-amps and amps. I suggest you spend some time going through them and try and find a way to try some out. The simplest would be to get a mandolin that already has a pickup installed and run it into an amplifier designed for acoustic instruments such as the Fishman amps mentioned above.

[Atlanta Mando Mike]

I will respond as if you have decided you are looking for a plugged in optiion as opposed to going inot the plugged in vs. microphone debate. If you get a good acoustic amp- the fishman or AER are great choices that I've had success with, you really don't need a separate preamp because there is already one built in. I play in both a bluegrass band that plugs in and strives for as acoustic sound as possible and I play with an electric band. I use the same set-up for both. I go from my mandolin to a volume pedal (which one is important-I use the Ernie Ball that has a setting for how much volume the pedal has at open position), a tuner (this acts as a mute too which is helpful), and to the amp. At the amp I very aggressively pull out frequencies. I pull out almost all of the mids, most of the highs and 75% of the lows. This, to me, gives the most acoustic like sound-it really sounds very similar to my mandolin. If a mandolin is treble heavy, I will pull out all of the highs. Even then, its a mandolin, its still got plenty. I get lots of compliments for the tone of the plugged in mando with this set up. The plus of an amp vs. just a preamp is you can control your tone/volume on stage, which really helps your playing. You always hear yourself and once you understand how to get the tone you are looking for, its easy to replicate.

[JeffD]

Jordan I feel your pain.

I am absolutely new to the world of microphones and amps and electric instruments. I am reeeeely ignorant about this stuff. I don't even know enough to be able to use the information in the above and other posts.

What I am finding is, like lots of things, there is no front door to this stuff. Everyone is where they are at, and while they are generous with their experience and understanding, (which I appreciate) I know I am just not getting it. What is a pre-amp, why do I need one, what is a DI, why do I need one, what is an equalizer, why do I need one. All I want to do is make this <pointing to my mandolin> really loud.

What I have decided to do is to just jump in. <I hear others shuddering>. I am going to budget a fixed amount of money, I am going, with a friend, to the store and say, flat out - here is what I want - here is what I have - tell me what I need. In other words, just get started. I am 100% sure that in five years I will look back on what I bought and feel like an idiot. But, I also know I will feel like an idiot anyway, cuz when it comes to this part of it, face it, I really am. I don't even know enough to act smart.

I found this article informative, and not too far above my present level that if I hand on tight, I can just reach it.

[Atlanta Mando Mike]

We are finally at a point where, if done thoughtfully, pickups can get you 70%-80% of the way tonally by using readily available, somewhat affordable equipment. Amp will cost 700-1300 bucks, that's the big spend-100-200 for the pickup, 100-200 for pedals, cords, and really you are pretty good. You can spend a lot more money-pickup plus a mounted mini condensor mic, very high quality preamps through a custom stand alone speaker cab with rackmount effects like full EQ (to pull feedback frequincies), compression, high quality effects... I think this will give you another 10-15% tonal quality but costs a ton more. Without a dedicated soundman, this is a tough sell

[Atlanta Mando Mike]

OK, last thing and I'm done.

I think there are 2 great options for a person trying to get a plugged in rig together for the first time:

1. (easy, most simple) Get a luthier to install a K&K twin pickup, get either a LR Baggs Venue DI Preamp http://www.sweetwater.com/store/deta...kHgaAr3v8P8HAQ or a Fire Eye-Red Eye preamp http://www.amazon.com/Fire-Eye-Devel.../dp/B0089EUZ4A , then plug into the preamp from your instrument, plug into the sound system from your preamp and you are done. Very easy, compact and works well.

2. Get a luthier to install a K&K twin pickup, Get a quality acoustic amp http://www.sweetwater.com/store/deta...pjEaApcw8P8HAQ, http://www.musiciansfriend.com/ampli...mbo-amp/h86846, plug directly into the amp, plug the microphone cord into the back of the amp to the sound system. Add a volume pedal or boost pedal if you want to to turn up when you take a solo.

[Jordan S.]

Get a luthier to install a K&K twin pickup...

The internal or external? I'm assuming it's largely personal preference, but is there a strong preference either way within the mandolin community?

[kkmm]

Here is a link to an ukulele topic about amplification, there are plenty of details there.
http://forum.ukuleleunderground.com/...-Amps-Feedback
I hope this helps.

[Atlanta Mando Mike]

Jordan, I only have experience with the internal. With that, they have to make 1 small mod to the mando. They have to enlarge the end pin whole a little so the quarter inch plug can fit. Its pretty minor but it is a modification.

[Austin Bob]

The internal or external? I'm assuming it's largely personal preference, but is there a strong preference either way within the mandolin community?

Go with the internal. Like Michael says, it does require proper installation and enlargement of the standard endpin hole, but a competent luthier should be able to install it easily and quickly.

The external is the same pickup, but it simply mounts to the outside of the body with a carpenter jack. I've used those before on a different pickup, and it never really felt secure, plus it did leave a small mark when I removed it.

Here's a pic from K&K's site showing how the external one is mounted.

[dang]

Jordan, I only have experience with the internal. With that, they have to make 1 small mod to the mando. They have to enlarge the end pin whole a little so the quarter inch plug can fit. Its pretty minor but it is a modification.

If you have a really nice mando you don't want to drill you can use the Vintage Jack. But you apparently would have to do a little wiring.

Never used one, NFI, just wanted to add that as an option.

[mandroid]

One thing .. dynamic Mics survive being spit into , your p's and t's & such ,
much better than moisture sensitive condensers..
so a foam wind screen can have a second function

My Rode mics came with silica desiccant packs that can be recharged heated in the oven and some Zip Lock bags ..

[Steve Lavelle]

Jordan-You can save yourself some money (~$100) by buying a pickup from JJB electronicshttp://www.jjb-electronics.com/prestige-220.html. Then go to a luthier to get it installed.

Piezo pickups are very simple devices, K&K are selling you a brand name. When I had my JJB installed, my luthier at Gryphon told me a story about a customer who stripped the alarm sensor (A piezo crystal with wires attached) from one of his windows at home and put it in a mandolin, and it sounded just like any other he had heard. Not sure if I'd go that far, because there are packaging considerations, but I am very happy with my JJB pickup. It sounds way better than the Fishman pickup built into the bridge that I used to use.

[Jordan S.]

...get either a LR Baggs Venue DI Preamp or a Fire Eye-Red Eye preamp...

If I understand correctly, these do essentially the same thing except if I get the Red Eye, I also have to get a boost pedal and chromatic tuning pedal, right? And the LR Baggs already has those functions?

[pops1]

If I understand correctly, these do essentially the same thing except if I get the Red Eye, I also have to get a boost pedal and chromatic tuning pedal, right? And the LR Baggs already has those functions?

I have had many preamps, the redeye is the one I am using now. It has a boost that you can set the amount of boost (gain) that you want. It's a simple preamp with a great sound. Go straight to the board, if you put a tuner or anything between the mandolin and the preamp you will not have the impedance match you need and will have to EQ a lot to get a decent sound instead of playing flat. Most preamps have an output for a tuner or, aux out, so you can use those with the preamp and maintain the match you bought the pedal for in the first place. A headstock tuner is cheaper and works well and you don't have to worry about anything else as far as pedals goes. Less batteries is better. The redeye will work with the phantom on the board so it won't wear out batteries and the headstock tuner is a small battery that last a long time, depending on the tuner of course.

By the way most tube amps work well without a preamp, if you are looking for that sound.

[Br1ck]

Take a look at the Carvin AG 200 or AG 300 acoustic amps. These are very good and both are less than $500. My AG 300 handles bass guitar to Uke and everything in between. Very much like a powered PA cab.

I'm a huge RedEye fan, simple high quality components. Not for someone wanting to twiddle knobs.

The K&K is a popular go to.

If you don't need a lot of power or a great vocal sound, plenty get by with a modest Fishman mini.

[Sheryl McDonald]

The RedEye does have a effects loop (in and out) you can run a tuner through, and not affect the sound.