The following article about the Innertube Audio U-87 Tube Retrofit was written by Bobby Owsinski and appeared in EQ Magazine October 16, 1996...

The Neumann U-87 is a fine microphone. In the prescence of some wonderful examples of vintage microphone like an M49, C12 or 251, however,it would not be my first choice for a lot of things, vocals, for example: nor would its tube predecessor, the U-67. So you can imagine my suprise while setting up for a recent tracking session when Richard Barron, the studio manager at Sonora Recorders, pulled out what looked to be a stock U-87 and said, "You should try this. It has a tube in it." "So what?", I thought, "67,87, it's not gonna have "the sound" I'm looking for." But, ever the experimenter and trusting the taste of Richard (who has quite a nice vintage mic selection), I figured it was worth a try.

My original feelings have now changed since using what turned out to be the new InnerTUBE Audio tube retrofit for the Neumann U-87. This retrofit utilizes the capsule and housing assembly of the standard 87 and includes a replacement internal tube preamp, an external power supply complete with pattern control, and all interconnecting cables. What's more, the retrofit is just about as instant as you can get, taking less than a minute to screw the exterior housing off, remove the solid-state preamp from the capsule assembly, and insert the new tube preamp. Plus it has the distince advantage of allowing you to return your 87 to "stock" if and when you ever want to .

It's hard not to throw superlatives around when you use an 87 with the InnerTUBE retrofit. I found it to be much, much, "bigger" sonically than a stock 87, with a lot more bottom and much more open on top.


Putting a tube into the 87 may give the impression that the mic automatically becomes a 67; nothing could be further from the truth, though the capsules are identical. "The U-67," says McLane, "is a totally different beast in that it uses an EF86, a very high gain pentode tube. It doesn't sound as good as a triode, but it has a lot of gain, which is why they used it. The tube I use is a 6072 dual triode like that used in the C-12 and 251, which-in my opinion-is much better soundng."

Although I didn't get the chance to match the InnerTUBE retrofit against a vintage U-67, I did get the chance to use it against both a stock transistor 87 and a few other vintage tube mics. I used the InnerTUBE retrofit on all the things that I might normally use a good 67 on-sax, percussion, acoustic guitar, distant guitar amplifier, even vocals. In every case, this mic blew away the standard 87 with no trouble at all. It was so much more open that it was like a blanket was lifted from in front of the mic every time we switched. And the difference was dramatic enough that not only the trained ears in the control room heard the difference; everybody heard it immediately.

When we put the InnerTUBE retrofit up against an M49 on a male vocal (which, perhaps, is like comparing apples to oranges) the difference was much less dramatic. Both sounded great, and you'd have to call it a taste judgement at that point. Still, the InnerTUBE retrofit held its own with no trouble at all vs. a very highly regarded (and expensive) vintage cousin-something that neither 87 nor 67 would be able to do.


The InnerTUBE retrofit is a real find. It is currenly in use at A&M, Bearsville and Westlake studios, and famed engineer Shelly Yakus had bought six. Yes, at $1500 it does turn your U-87 into one pricey item, but at least you know what your getting in terms of a new piece of epuipment likely to give you years of trouble-free service as compared to the sometimes finicky ways of something 30 years old. Plus, it has "the sound" and it's got it in spades. InnerTUBE will soon come out with its "Four-Fifty-Tube®" retrofit for the AKG 451/452 series-a development that I eagerly await.

Manufacturer: InnerTUBE Audio, P.O. Box 610 Los Olivos, CA 93441.
Tel:(805) 688-8286 Price: $1500.