JPF Home Page Forums Musician Gear and Techniques Recording Studio and Gear Forum Let's talk Mic preamps...

What are you guys/gals using for mic preamps? ART seems to have the low-end market share and I haven't tried any of the MP line. There seems to be a bunch of new variations on that basic little preamp - which I've heard is pretty good for bass guitar.

I've used the preamps in my little 001 occasionally, but I find they're mediocre (about like pre-VLZ Mackies). I've also used the higher-end Avalon 737s, Neve 1272s, and a wonderful-sounding D.W. Fearn.

A lot of people are buying the DBX preamps it seems, too. Presonus is making some nice mid-priced gear.

My main preamp is a Studio Technologies Mic Pre-Emminence which has been highly modified by Jim Williams at Audio Upgrades. It has a sound similar to a Millenia Media (pretty much straight wire with gain).

I'd love to get a more "colorful" preamp at some point and have seen (but not heard) the newer Summit Audio pre's.

FMR Audio is supposedly (for quite some time now) coming out with a "Really Nice Preamp" (RNP) to match their RNC (Really Nice Compressor). I have the RNC and it really can't be beat for about $175.

Are you tending more to get "vocal strips" with built in EQ and compression and maybe de-essing, or dedicated preamps?



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Larry
www.audibleresponse.com

Hello, Larry!

Being on a budget, I find the Art Tube MP to be a nice general purpose tube pre -- I've used it with vocals, guitar, and you're right; it is perfect with Bass if you're doing a DI. I also rely heavily on a dbx 386, and use it mainly for vocals (it's next in the chain starting with my Vocalist EX Workstation), and guitars (warms up a Strat single coil without losing the bite...). Oh, I own three Tube MP's, two basic ones, and one "Studio" Model. No difference except for the built in limiter and cool analog meter.

Mike Melton
PanikAttack

I've just this week been putting to use my new ART Studio V3 in my project studio. I've used it for everything from acoustic guitar with my Shure AXS4 (Do they still make those?), vocals, and even an egg shaker. The ART was a "dent 'n scratch" through Musician's Friend and ran me under $100, which I figure is a GREAT deal considering the sounds I'm getting out of this thing. And it's fool proof with its preset dial settings and UV meter. On my latest album, we used Avalons because that's what the studio owner HAD to use. Sure glad I wasn't the guy footing THAT bill!

Hi Larry,
First lets discuss why you need a Mic Pre Amp. A pre-amp is used to build up a very small signal to be able to be fed into the main amp without hum or distortion. It would seem that a microphone that needs a pre-amp, would come with it as part of the package. As far as I know Condenser Mics use a pre-amp but Dynamic mics do not need a preamp because they have enough output to drive the amp to full output as is. The possible exception is if you run very long cables where you will lose something such as frequency response. I don't know what the maximum length cable you can use on a dynamic mike but specs may be included with the mic when you purchase it. Pre-amps are pretty simple items and any good pre-amp should do the job. Pre-amps should not modify the signal but give a perfectly flat response within specs which are very easy to achieve today. Once again any mic that needs a seperate Pre-amp should be included with the mic. On that note I would not mix and match pre-amps. I would use the one that should be included. If you did not get a pre-amp with a Mic you don't need it. Hope this helps.

Hi, Ray.

Wow, you’ve said a mouthful there. You’ve given me a chance to do a short dissertation in this area. I hope you don’t mind. I had to do a little research to verify my own facts before I replied to the first part, as I’m not an electrical engineer (E.E.). I can tell you easily how to use these things for recording or live use, but I really hadn’t studied the electrical component design details enough to feel confident in giving you a worthy response.

It may be that we’re simply talking about different terminology. IF we're talking about preamps which are integral to most mixing boards/PA systems, or preamps you buy separately (as mentioned above), then no microphone that I’m aware of, whether it's dynamic, ribbon, or condenser comes with a preamp as we're using the term here. This includes a lowly $19 Radio Shack special or a $7000 vintage tube mic.

This is not to say there isn't electronic circuitry in mics. However, that little bit of circuitry is not generally called a “preamp” in the recording engineering field - although it may be technically correct to call it that in the E.E. field. According to several sources I checked, the few electrical components in a mic serve two primary functions:

1. to isolate or buffer the capsule/element from the downstream electronics such as pads and filters; and
2. to provide a balanced output of a specified impedance.

This is done either with a small transformer in traditional designs, or with transistors (FETs) and a few other components in newer, less expensive designs (“transformerless”).

Now let's back up a bit and clarify the issues here.

Microphones typically put out a signal level in the millivolt range (1-10 millivolts is typical). That's the voltage that appears at the end of the cable where you plug it in to your mixer or preamp. Of course it also requires some input (sound) to generate this voltage. It has a certain impedance (resistance or "effort" to push the signal through). Professional recording/live microphones (vs telephone, walkie-talkie, or pilot mics) generally have an output impedance in the 200-800 ohm range. It’s the impedance that determines the maximum cable length, not the design of the microphone. Because of this low impedance, mic cables can easily run 200 feet or more with no noticeable (or at least significant) loss in fidelity. Anytime you’ve seen a concert at a stadium, they are running mic cables hundreds of feet through a multi-core cable. Still sounds ok, doesn’t it? They are most likely using a mixture of dynamic and condenser mics on stage.

Some very old or very cheap microphones have a high impedance output (50,000 ohms or so) and on those types of mics, you can only run the cables 15-20 feet without noticing degradation. In the past 20 years or so, components have become cheap enough to allow low impedance designs to be very affordable. However, even now when price is the major consideration (vs hi fidelity), high impedance designs still serve a function. Consider, for instance, the microphone in your cell phone or the headset you can use for it. It’s cheap, but you won’t be able to run a 50 ft extension cable on it and it won’t sound very good recording your band with it.

The difference between condenser and dynamic (moving coil) microphones is that dynamic mics produce a voltage based on moving a coil of wire within a magnetic field. ALL dynamic mics have a magnet in them and all have a moving coil. That is by definition. This includes many live recording mics such as the common Shure 57 and 58 as well as many mics also found in studios, such as AKG 421s and D112s. Dynamic mics are really very similar to a regular speaker, but used in reverse. In fact, I was just reading an article on how a couple of famous producers were using 12” and 15” speakers as microphones to get more “whomph” out of bass drums and bass guitars.

Condensers on the other hand produce their voltage because of a change in the capacitance of their two elements. No magnetic field is involved. There are two primary elements: the polymer film (diaphram) and the back plate. Sound causes the diaphram to move thereby causing (inducing) a change in the capacitance between the two elements which is then converted into a voltage. There are also TWO types of condenser microphones:

1. Externally polarized. These are usually the more expensive microphones and require an external voltage to be applied to the back plate. This voltage is called “phantom power”. 48 volts is typical although there are some very high-end mics which require 130 volts of phantom power. Most recording consoles and many PA mixers have built-in phantom power specifically for this purpose. Just about every decent preamp provides it.

2. Pre-polarized. These are also known as “electret condenser” designs. They have one of the two elements permanently charged so that all they need is a small battery to fully be operational. The battery plus the pre-polarization process replaces the requirement for phantom power although every one I’m familiar with can use phantom power if no battery is present.

Phantom power is carried through the standard 3-prong mic cable to the mic.


Preamps CAN be pretty simple devices. There are several do-it-yourself schematics available on the Internet for building your own if you like breadboard types of projects. Millennia Media has an excellent paper available on design techniques for mic preamps, also. Other than choosing a Class A design or a Class AB design and adding a few bells/whistles and ease-of-use features, there’s not much more to them. Check out their site at www.mil-media.com

Some manufacturers do believe that a mic preamp should simply be “straight wire with gain”, adding no coloration at all to the sound. Some preamp manufacturers abide by this philosophy and are used in recording orchestras, jazz ensembles, and other sources requiring purity in the capturing of audio. Some of those brands are Earthworks, Millennia Media, and Grace Designs.

Other manufacturers feel that a preamp should somehow “enhance” the sound and make it more musical. Of course it’s entirely subjective as to what will “enchance” the sound, but there does seem to be a certain amount of agreement as to which brands do this and are worth purchasing specifically for their “sound”. Brands such as Neve, API, Joe Meek, Manley, and Avalon, to name a few are noted for “something special” about their sound, but aren’t considered to be “pure” in their sound.

A new trend in preamp design is to include capabilities to change the sound of a preamp by introducing various components into the circuit or manipulating the operating levels of some of the components. For instance, several new preamps have adjustable input impedance to allow one to match it better to the exact microphone you’re using. Others can add or remove a transformer to the circuit, or run the signal through either opamps or through tubes, effectively allowing you to select some of the design elements used. Most of these preamps are on the high priced end of things ($2000+). Interestingly, Millennia Media is one of the companies with these multiple design capabilities in one of their high-end models (around $3000).

Several companies in the mid-price area are also allowing you to add a certain amount of selected harmonic coloration (distortion) by overloading one of the circuits in a very specific manner. Envoice’s Mindprint comes to mind as well as several DBX models, although there are others, too. They allow you to introduce a supposed “tube quality” to the sound, although many don’t even have tubes. In some cases, the tube is really just there for marketing appeal and doesn’t really affect the sound significantly. However, these are preamps selling for well under $1000 for a dual unit. Whether it “improves” the sound is entirely a matter of opinion. It does give you some additional flexibility. However, that price range is selling really well.

Finally, mixing and matching preamps with microphones seems to be a discussion past-time on some of the pro audio forums on the net. Much discussion occurs on whether one microphone sounds good with such-and-such a preamp and with such-and-such type of music or source (guitar, vocal, trumpet, etc). Just like questions about “Which microphone is best?”, endless discussions about “Which preamp is best?” are all over the place. And like with most things…there is no ONE right answer.

I’ve run out of breath at this point, so maybe someone can cite an example when they deliberately didn’t want the cleanest sound available from their preamp and dirtied it up on purpose…or chose a preamp for it’s “sound”, or just talk about your preamp and why you chose it.

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Larry
www.audibleresponse.com


[This message has been edited by Lwilliam (edited 08-08-2002).]

Hi All,
Perhaps I should add some items to my earlier post. The most important thing when using a Mic is what comes out to the final product be as close to what entered the Mic as possible.

I had mentioned that a microphone that needs a pre-amp should also include the pre-amp with the mic. Possibly there are mic manufacturers that do not make pre-amps to sell with the mic. In this case there should be a recommendation from the manufacturer of the mic of a pre-amp that will work with the mic. If not there could be problems in the final product.

I had mentioned that a signal has to be amplified enough to drive the main amp to full output with out distortion or hum. All circuts before the main amp such as a guitar amp or recorder are designed to require one volt of peak power to do this. Of course there are level controls on guitar amps and recorders to prevent gross distortion.

While there may also be level controls with some mic pre-amps if the pre-amp doesn't have enough "head room" it is possible to add what is known as clipping to the signal. This happens when the signal, from the mic, in this case, continues to increase but the pre-amp can no longer increase the output to the next stage. Therefore if you occasionaly get harsh sound from your system this could most likely be the cause. This is much more annoying in solid state devices than tube circuts. Well I don't want to teach a college course here, you will have to go to college for that! There is tons of equipment to record with out there. Also lots of opinions of what is best. Shop careful. RES.

Yep, every condenser microphone contains some kind of circuitry to bring the tiny, tiny output of the diaphragm up to a level suitable for plugging into what we call a "preamp". An externally-polarized mic will usually have a circuitboard inside with the circuit on it. An electret or pre-polarized mic element will have a tiny transistor pre-preamp built-in as an integral part. That's why you need a battery for that type; to power the transistor.




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Later,

Pat

transistors, resistors, it's all too much. i just want to plug and play. if i wanted to design i'd go to school.

that out of the way. i generally use an at4033sm mic as i'm sure alot of people do. i first bought an art tube mp like everyone does. but i found that the tube mp colored the low end of my recordings. great for bass yes. but if your using one mic and one preamp then you end up with mud. so i just use the built in pre's on my behringer. i picked it up at musician's friend's scratch and dent for about $100. now the model i have is $90. it is extremely clean, and i'm looking into their mics for the future.

just my 2 cents

jt

I have a MindPrint Envoice tube preamp.
It's a German-made preamp that has alot of versatility as far as sound, input/output options, and mastering capabilities.
It can go from transparent to very warm, depending on the amout of tube saturation, and also has compression and extremely accurate eq capabilities.
It also has S/PDIF in and out and the converters are phenomenal for a unit that costs less than $500.

My next preamp acquisition will be a Joe Meek VC1Q for that "British" sound.

Here's the mics I own...

RODE NTK (tube mic)
AKG C3000
RODE NT-3
Shure SM-57 (5 of them)
Audio Technica DR2000

Yeah, either I'm going to spring for an Avalon 737, or get something else (cheaper) with some kind of "personality". I've had trouble taming the compressors on the Joe Meek stuff (maybe TOO much character for me?), so I don't think I'll go that direction myself - but a lot of people like them. I'm curious about the ART preamps with different "character" switch settings for vocals, bass, guitar, etc. if anyone has tried them. I know I'd muck around and use a guitar setting for bass or something, but that's OK. If it sounds good, it IS good.

The only thing I don't like about my Studio Technologies preamp (especially since it's been upgraded) is that it's so darn clean, it doesn't have any character. What goes in, comes out - BORING!. I'm certainly glad I own it and it's been a great asset to my little studio for almost 10 years now, but I'm ready for something new, I guess (I sure won't sell it).

I've tried a few preamps that make you go, WOW! That sounds GREAT, versus preamps that make you go, "Yep, that's what it sounds like". Since I have a super clean preamp for acoustic guitars, flute or other instruments that you just want to "document", I'm definitely looking around for something with a little character, and that doesn't necessarily cost me two grand. Brent Averill (here in So Cal) makes some very nice totally refurbished Neve and API preamps; Vintech also makes a Neve-like preamp. Things just somehow sound "better" through a Neve. Most of these are around a grand or so.

Summit Audio has a new tube pre/DI for around $500; I'm waiting for the reviews to hit the stands. The Mindprint is another very curious, and versatile animal. Maybe I'll try one of those, too.

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Larry
www.audibleresponse.com

[This message has been edited by Lwilliam (edited 08-09-2002).]

I have a ART Dual MP and have quit using it for vocals. I have a low voice with a bit of growl to it and I've had a lot of problems with excessive distortion in the vocals when using this preamp. The preamp works well enough for mellower vocals. I'm presently using a preamp designed and built by one of our band members (who is an electronics engineer) which doesn't seem to have this problem.

Want a mic pre that can change character? The you should look into the Vipre from Groove Tubes. It's a variable impedence mic pre and it can make one mic into about 10 different type of mics.

Worth checking out.

Jody