An ambitious evaluation of microphone preamplifiers, encompassing 33 preamp and four sound sources, has been conceived and implemented by Lynn Fuston of 3D Audio Inc. of Franklin, TN. Billed as the First Annual Invitational 3D Audio Preamp Listening Party (PreLP), the event took place April 1 and 2, 2000, at Franklin's Classic Recording. "After 20 years of evaluating preamps on different instruments and vocalists myself," Fuston comments, "I decided it would be very valuable to come up with a way for other people, who don't have the luxury of having 5 or 10 preamps in the same room, to be able to hear the differences for themselves." The preamps assembled range from $100 to $8000 for a stereo pair, from manufacturers as diverse as Presonus and D.W. Fearn, and including some vintage preamps from the likes of Neve and Focusrite. The results of the experiment were recorded to hard disc to be released on a pair of compact discs.

 

Procedures for the evaluation were developed through consultations with designers Dan Kennedy (Great River), George Massenburg (GML Labs), John LaGrou (Millennia Media), Greg Mackie (Mackie Systems), and Tim Farrant (Buzz Audio, NZ), all of whom had their product lines represented in the test. Dan Kennedy constructed a custom ten-channel passive attenuator network that provided the means of calibrating the various pres to within 0.02dB. Kennedy was on hand to personally implement the level-matching scheme. A tone source was fed to an Auratone cube affixed to a mic boom arm rigged to provide the stimulus at a repeatable distance from the microphones. The calibration routine was repeated for each source and microphone combination in ten channel groups, with the reviewers out of the room, and the front of the preamps were covered so no visual cues were given to the participants. Musical performances were repeated for each preamp.

 

Four sound sources were used during the tests: a female vocal sung into a Manley Reference microphone, a modified AKG C-414B-ULS on male vocal, a stereo configuration consisting of a Neumann KM-84 and a Audio-Technica AT4033 on acoustic guitar and a Shure SM57 on snare drum. The listeners rated each pre in subjective terms without knowledge of the pre being listened to while documenting their opinions. Once the identities of the preamps were finally revealed, the attendees report being surprised at their inability to distinguish the differences between tube and solid-state pre-amps, or to correctly identify some of their favorite devices. The performance of some preamps expected to perform well proved disappointing, while others provided a pleasant surprise.

 

Volume 1 of the 3D Pre CD, comprised of the female vocal and guitar tests, and Volume 2, featuring male vocal and snare drum, are both shipping now. The discs are priced at $29.95 each, and are available through the 3D Audio website, www.3daudioinc.com. Early release discs have received a range of comments, from enthusiastic praise for the project as a valuable reference, to those who heard no significant differences between any of the devices. These reactions reflect the goals of the project, letting the potential end-user hear for themselves and draw their own conclusions. More detail and photos from the testing can also be found at the 3D Audio website.

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Some people might consider Lynn Fuston a bit of a maniac. After all, what else would you call someone who spends two months planning and arranging a weekend-long listening comparison between 33 microphone preamps?

 

Fuston is the owner of 3D Audio, a mastering and mixing facility in Franklin, Tennessee. He claims to have been crazy about mic preamps since he bought his Focusrite ISA-110's in 1987. Given the myriad of preamps on the market these days, he was curious as to just how much sonic difference there really was between the various offerings. Were the expensive preamps really worth that much more than the inexpensive? What was the truth behind all the hype and opinion out there? Lynn set out to examine these questions with the help of some friends. Here's how 3D Audio's Great Preamp Listening Party went down.

EQ: So what was the premise of the 3D Audio Preamp Listening Party?

 

Some think it was a shootout, but it started out as a party, a bunch of engineers getting their preamps together in a single room to listen to all of them with a single source. We weren't trying to pick winners and losers. We wanted to find out once and for all what differences, if any, we could hear when the pre's were accurately level-matched. Some console manufacturers insist that the differences people hear between preamps are volume related, due to inaccurate calibration. I couldn't disagree with them until I scientifically set up a listening test that absolutely ruled out that variable. That's what I wanted to accomplish with this party.

 

EQ: How many preamps did you have all together?

 

I was able to get 33 preamps in one control room for two days. We had a price range from the Mackie 1604 VLZ Pro at $65 per channel all the way up to Neve 1081 modules at $4000 per channel. All told it was over $75,000 worth of preamps.

 

EQ: That's quite a lineup! What acoustic source did you use? Or did you listen to several?

 

Originally, I considered just auditioning female voice. I do a lot of female artist records and I've found the preamp makes a huge difference. But after getting all these preamps together, I wanted to hear as many sources as possible. I added acoustic guitar (in stereo), male voice, and also snare drum. Those are the primary instruments I use external mic pre's for in the studio anyway.

 

EQ: How long did you spend on this project? How many days did it take in the studio?

 

The planning stage took about two months. Once all the preamps arrived, we spent one day setting up and two days listening, broken into three-hour sessions per source. Add in a BBQ dinner, lots of tech talk, a few hours of looking "under the hood" at several preamps, and then several hours boxing them up, and we had a very long weekend. I called it Preamp Boot Camp. Very tiring but very rewarding. And very revealing.

 

EQ: Revealing? In what way?

 

We all thought we "knew" certain things, like the way our personal preamps sounded. Like the sound of a tube preamp versus a solid state design, or the sonic difference between a discrete component design versus an all IC design. These are things you learn after years in the studio. Like the "sound" of a Neve preamp versus a Mackie or a Manley or an API. The listeners, ranging from professionals to weekend recordists, had dozens of years of experience with many of these preamps.

 

What we discovered is that if you wipe away all the preconceived notions about brand names, designs and circuitry, and just let your ears decide, you might be surprised at what you prefer.

 

EQ: How could you listen without those biases?

 

All the tests were completely blind. No one but the tech staff knew which was which until after the listening was complete. The listening order was completely random, determined by drawing names out of a coffee mug.

 

EQ: How could you keep their identities secret while sitting in front of the rack?

 

We stacked them all up and hung fabric in front of them while we listened so we couldn't see the meters or peak LEDs. It was absolutely fair in that regard. Dan Kennedy of Great River supervised the patching and calibration.

 

EQ: How did you calibrate them?

 

We used an Auratone duct-taped to a boom stand that we would swing into position in front of the mic. We used a pencil taped to the speaker to keep the mic-to-speaker distance consistent. We connected each mic to one preamp at a time, fed a test tone into the speaker and then adjusted the gain on each preamp to within .02 dB. That was close enough to make sure the "volume difference" argument wouldn't come up.

 

EQ: Two hundredths of a dB? Seriously?

 

Yes. Dan Kennedy used a Tektronix scope to check for polarity and a Fluke meter to calibrate the gain. He also built a very minimal circuitry trimmer box to allow calibration that accurate.

 

EQ: What mics did you use?

 

I wanted a variety of mics ranging from expensive down to a common mic that everyone owns. I chose a Manley Reference for the high end, then a modified AKG C-414B, a Neumann KM-84, an Audio-Technica 4033 and the standard Shure SM-57.

 

EQ: So how did you conduct the listening tests?

 

I would decide on the mic and position for each instrument, the female voice for instance. We listened to solo voice with no processing or reverb. The signal path was mic > preamp > trimmer > console. We also recorded the results to hard disk so we could listen back later.

 

We sat at the console and listened as she sang through Pre #1, then we wrote down our impressions. We each had a list numbered from 1 to 37 (some of the 33 pre's had alternate settings), so we would repatch, resing, and write down our impressions of each one, until we had heard them all.

 

EQ: Could you possibly make meaningful judgments after listening to the same thing 37 times?

 

Absolutely. It was amazing how much difference each one made. The comments would range from "nasal, yuk" to "sublime." Sometimes several in a row would sound similar , but then I would hear one that just blew me away. Each of us picked our favorites, and among the six listeners, every person had a preference. Usually we each chose different favorites. On snare drum we had a more uniform consensus.

 

EQ: Did you rank the preamps by preference or make a list of favorites?

 

I didn't do any tabulation of the results to determine a winner or most-preferred mic pre. That would be missing the point. There are lots of written reviews that will give "one man's opinion" about the sound of a pre. I don't agree with making sonic decisions based on written opinions. I wanted this event to let listeners decide for themselves using their own ears. When it comes to preamp differences, one man's "subtle" is another man's "sublime." You've got to hear them to decide.

 

EQ: So tell us what you learned. Were there any startling revelations?

 

I learned that you should rely on your ears alone to judge preamps. That sounds obvious, but there are so many biases and prejudices out there, unless you listen blindly, as we did, you can't be truly impartial.

 

The big surprises? Some "revered" preamps didn't blow us away. Some that we expected to hate, we actually liked. Some we thought we would recognize, we didn't. Some we had never heard before jumped to the top of our "must have" lists. I think everyone who was there discovered that there is no "one best preamp" for recording everything. We all became more aware that we need to invest in more preamps.

 

I think that the CD of this event, the 3D Pre CD, will be very valuable in helping people decide just what they can or can't hear. It also comes with an encoded "key" so people can listen and make their notes before seeing which pre was which. Some people may not be able to hear the differences. I think most engineers will. Then they'll recognize the limitations of their current preamp lineup.

 

EQ: How can someone get a copy of the CD?

 

The ordering info is at my website, www.3daudioinc.com. There are also pictures and a complete list of the preamps. I had to break the recordings into two volumes just because we had so many preamps. Volume 1, which is shipping now, has female voice and acoustic guitar. You should hear the acoustic guitar samples. It is absolutely amazing the recording you can make with just two mics, absolutely flat, with the right preamp. You need to hear it.

 

Eddie Ciletti (contributing technical editor to Mix Magazine) writes:

Congrats on getting the levels so close. You succeeded in making evaluation more difficult!! <G> And congrats on choosing a vocalist capable of being so consistent. With just a few exceptions where the pitch was different the performances made a difficult evaluation easier.

Overall, you are to be commended for every facet, especially patience if not tenacity. I can just imagine how much work went into this -- and you're still married?

 

Doug Fearn of DW Fearn preamp fame writes:

 

I received the 3D Pre CD yesterday and gave it a quick listen last evening. You are to be congratulated on an excellent job!

The performers are excellent, with amazingly consistent performances from cut to cut. And the calibration and recording of the preamps is truly the best I have heard on a project like this.

I listened through the first time without reference to preamp list, and was impressed with how many great-sounding units there are out there. Although there were a few obvious second-rate preamps, most sounded very good, with their distinctive flavors...

There were a few surprises, both good and bad, but in general, I think engineers will have a great tool for objectively evaluating preamps. Plus I think it will dispel a few cherished notions held by many.

 

The 3D PRE CD-The easiest way to hear $75,000 worth of preamps in your own studio.

 

To order your copy of the 3D Pre CD, Volumes 1 and 2, click here.