I brought one of my DU67s and Bock 251 to a test session where we compared them to 5 other tube mics in different applications - vocals, electric guitar, acoustic guitar, mono drum overhead, and cello. The studio owner had two Brauner VM1s (both Klaus Heyne Edition, not matched pair, about 40 serial numbers apart),a KM56, M269c, and a M49b (which sadly only got to be used in the last few tests bc the B room was using it for most of our session).
The DU67 I used for this shootout is the 2nd one I built which is using the Heiserman H67 capsule, AMI T67, and silver shield Telefunken EF86. It sounds better to me than the first one I built because of the capsule most likely. There's a little bit more low and top in mic #2. I ordered the HK67 that's in my latest 67 2 years after I ordered the first one, so it could be that the capsule construction is a bit more refined, the tensioning was different, or Eric just got better at building them. He claimed in a PM from a while ago that the construction is the same, so it could just be different tolerances between capsules. Despite what I just wrote though I still use DU67 #1 all the time.
Of course with these threads YMMV, this is not a scientific test, yada yada. I don't have the audio from this session at the moment.
So here are my comments/first hand opinions:
We put up one mic at a time, taking care to place mics in the same location every time they were swapped.
The VM1s sounded quite different from each other - one was brighter than the other, but the other had more of a defined low end. They fared well on everything and had modern clarity to them, but everyone in the room liked the DU67 better on the male vocalist (upper tenor-alto range) we were recording. The bright VM1 was particularly great on drums but the darker one felt more balanced, especially for guitars and cello where it felt like the focus was on the whole instrument instead on a specific higher frequency range.
The KM56 was incredible on drum overhead and was also really nice on guitars, but it didn't impress us too much on vocals and have the low end presence we would have liked on the cello. There's something old timey sounding about the mic with the way it saturates the upper mids that is really cool for certain applications.
The Bock didn't match well with the singer we were recording and left something to be desired when recording guitars (the studio owner said it sounded a bit "generic"), but sounded great on the cello and perfectly useable as a mono overhead. The low end on that mic is beautiful.
We only got to try out the M49b on cello and acoustic guitar but didn't really like it too much for close miking applications. The mic was backed off a feet from the source after that and we liked how wonderfully mellow the tone was. TBH, I think I have to spend more time to get to know that mic better before drawing any conclusions. It does seem to do this thing though where it takes a lot of the harshness out of whatever you're trying to record without sacrificing any high end clarity.
Going into the session I was almost certain that studio's M269c was going to straight up destroy the DU67, but the results were surprising to us because the DU67 did better in every application. This M269c was brighter in a pleasant yet somehow not sibilant way, but it lacked the midrange and low end definition/thickness that the DU67 had. Go figure. I don't know if this M269c has the original capsule, AC701k, or whether if it had been reskinned or modded. It was using a Korby PSU. I'll definitely want to look for other M269c mics at other studios in the area and compare my DU67 to those.
The only test that the 67 didn't do that great on was the mono drum overhead, which while sounding nice on the cymbals the overall sound was not as detailed on the toms and kick drum as they would need to stand on their own without any close mics for my tastes. It sounded a bit too 1960's to me in this application (which some people might actually prefer). The KM56 was the clear winner in this situation, though the VM1 and Bock 251 were quite usable too. On cello and guitars, the DU67 sounded especially great and balanced throughout with the low end that we wanted from the proximity effect (I have the 40hz filter removed on mine).
The studio owner was so impressed with my DU67 that he decided to rent it from me(!) to record cello and violin at his studio the next day. I wasn't expecting that. ;D
I was so surprised with the results of this session to the point where I am questioning my future plan to upgrade my HK67 cap to a Neumann cap and swap out the T67 for the AMI BV12. To me it's uncertain if paying $1300 for these parts would result in a mic that's better or just different. And at that price I can build myself another DU67 (lol). Maybe I should just leave well enough alone, we'll see. Like the VM1s used in this session, the vintage 67s I've used before sound different enough from each other tonewise that I know I am definitely in the ballpark with mine.
