TNC ACM-1200 Microphone Mod
Posted by DibS in 
ACM-1200 Mic
I purchased a pair of these through the TNC group buy. Again, these are rebadged Apex 460′s (among others) so the same mods apply. See my DIY Meta for more details. Overall I would say they sound bright. The bottom end certainly filled in after initial tube burn in. That bottom wasn’t exactly the most defined bottom I’d ever heard, though. This post will be updated to include all of the mods I’ll be doing to these mics. So with out further delay, the mod:
The first thing I’ve done is order new tubes. I bought a pair of Phillips JAN 5751s from tubedepot.com. I had them tested for noise and microphonics. I put them in last night and let them burn in overnight. The sonic difference was slight. I would say that the center frequency of the high end bump that this mic naturally has moved down slightly. The top end isn’t quite as sizzly and there seems to be a slight boost in upper mids. The difference is minute, however. This week I will order some transformers and caps.
Michael Joly says:
Try swapping the stock capsule for a K47-type. Most folks mod the electronics but the leave the stock capsule in place. The flat response circuit in these mics really begs for a K47-type capsule. best, M
DibS says:
I was lucky enough to get a pair of M7s from Dales recent run. I haven’t updated the post here yet, but I’ve already started experimenting with the circuit. My experimentation seemed to mirror the experiences of the guys on the APEX 460 thread on the now defunct studioforums.com. I’m pretty much in line with LDT2′s hybrid mod. He used a K47 with 2480 and did things like increase the value of C8 to 3.3uf. He didn’t remove the cathode follower in that one but I’m going to try it both ways and see what I like better. I’m transformer shopping now… Hint hint…
Thanks!