A treasured RCA 77 DX

There are so many wonderfully documented mic shoot-outs, comparisons and evaluations (some of which are exhaustive) that it would seem that everything that can be said, has. But recently, after modding one of my pairs of ribbon mics ( I put Lundahl transformers into one of my pairs of Cascade Fat-Head mics), I was setting up for a comparison test between the un-modded and modded mics when I decided to add another 4 different ribbon mics and place them all in front of a guitar amp. Some of the results were just as expected, but a few were surprising, even after using some of these mics for decades, and I felt that this was too fun not to share.

The contestants:

note – Because I was using electric guitar for the test, I left a few of my favorite ribbons out, like the RCA 77, because they don’t like high SPL’s. Sadly, I didn’t have an R121 or 122 available for this either.

Beyer M160 – An incredibly versatile mic, the M160 actually has two ribbons, giving it a hypercardioid pattern. This has been one of my favorite electric guitar mics, I perceive it as having a smooth high end and good mid-range punch. I’ve never liked it on trombone, but it works okay on trumpet in a pop horn setting. Current price around $700 new.

Cascade Fat-Head – At $150 new, the Fat-Head is the lowest price microphone in the group. I was impressed enough with the mic during a quick shoot-out on trumpet (it beat out the AEA R92 by a landslide) that I bought a couple of pairs. I’ve enjoyed them on brass, guitar amp and as room mics for vocals, drums and strings. They tend to loose a little body (lower mid-range) when used in room configurations.

Fat-Head with Lundahl Transformers – On the recommendation of engineer Mikey Allred, I replaced the stock transformers in one pair of the Fat-Head mics with the Lundahl LL2912.

Coles 4038 – The 4038 was originally designed by the BBC for broadcast and recording use. It’s a standard in studios because of it’s extended low end (flat to around 30Hz) and high SPL tolerance. I like these mics for trombone, tuba and drum room. They are murky on electric guitar and trumpet but are glorious as drum room mics if you like a bit of “boom” in your “boom boom.” At $1200 new, they are mid to high price for ribbons.

Bang & Olufsen BM-5 – A rare mic, the BM-5 is a stereo ribbon from the 1960’s, It’s inovative design inspired the Speiden SF12 stereo ribbon mic which later begat the Royer stereo mic. I’ve used this on some group vocals and it sounds very natural drum kit in the drummer POV (right over the drummers head.) Though I had it re-ribboned (by Mr. Clarence Kane, who’s worked on all of my ribbons) it has VERY low output, even into my altec tube pre-amps which have the lowest input impedence of any of my pre’s. The BM-5 has a noticable top end roll off, making them better suited for room applications. These sell for around $500-800 used.

Altec 639 – Also known as “The Birdcage,” the 639 was developed around 1938 and has the innovative design of having both a ribbon AND a dynamic capsule in it. Heavy as hell and able to withstand virtually any SPL known to man, this mic still sounds great on a bunch of stuff… the ability to choose ribbon, dynamic or both adding to it’s versatility. I’ve seen these mics sell for anywhere between $600 – $1800 used.

The Set-up:

The six mic comparison set-up

As this was originally going to be a quick before and after comparison of my Fat-Head mics, I had set up my Marshall JCM 800 into a Mesa 4×12 cab with Vintage 30’s to test both distorted and clean tones. I ran all of the mics through the preamps on my Neve V-series so that the pre’s would all be pretty closely matched (and because of the recent renovation of the console, it sounded pretty great), and recorded all of the mics flat directly into Pro Tools via HD I/O at 96k/24 bit.

While it’s tricky to place 6 mics in similar relative positions to a speaker cone, it’s even harder when several of them have massive magnets in them, attracting and repelling any other mics near them. So I ended up using the two top speakers instead of just one, but I test-listened to both speakers with one mic and found them to be very, very close. All six mic capsules were placed equidistant from the voice coil of the speaker they were on.

The Results:

Here are soundbites from each microphone of a recorded passage. As you listen, keep in mind that ribbons have very pronounced proximity effect and that how these mics sound in this close application doesn’t offer a full picture of it’s usefulness in other, more distant, applications. Oh, and please don’t judge my playing… this wasn’t intended for public consumption!!

Beyer M160
Altec 639
Fat Head
Fat Head Lundahl
Coles 4038
B&O BM-5

The Verdict:

Based on this listening, and much to my surprise, for close mic’ing electric guitar with a ribbon mic, I’d probably grab the stock Fat-Head first. Who’da thought. It seems the most open sounding, with a nice, useful low end roll-off (though not as pronounced as the M160) and smooth highs. The Altec was shockingly good on the amp and had a cool, unusual sound I liked.

This little test was inspiring. Because we so often think that, based on past experience, we know what mic will sound best in a given application, the tendency might be to put up just one microphone and change it out only if it doesn’t sound optimum. But I now intend to repeat this test with distant mic’ing applications and on different sources, like brass (which is where I use ribbons most often) so that I might have a better understanding of the tools I use everyday and make even more informed choices. I encourage you to do the same.

Altec 639 and Coles 4038


Fat Heads, M160 and BM-5

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