So it was the tnc acm-1200 which is the same as the apex 460 but with a hpf sliding switch on the mic body.
First thing I did was remove that filter - it imposes in my view some pretty major restrictions on the circuit.
Once that gone, the usual remove some other un-needed caps, change a couple of other ones, two or three of them.
After that, I rebiased the tube circuit away from the horrible state it was in due that filter.
I kept the original amp config which I like, but changed tube type to ay7.
That alone fixed a lot of the trouble.
But then, of course, I replaced the capsule. I used a good quality chinese k67 type from BeezNeez. Still very affordable.
That made a huge difference and that was that, really.
I measured up the stock traffo and couldn't see any real problem, so I kept it.
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End result was the mic, remained quite affordable but performs quite well.
However, I would be happy to do a transformer change too. Cinemag would be my choice.
Certainly the thing that bugs me now about the apex 460 style mods + ACMP81 mods chain, is now I can hear the *really* tiny hiss in the combo (I mean barely audible at typical recording levels).
The major issue is how well I can here the tinyest gnat farts in the room now!
What I thought was a very quiet computer fan is the biggest impacter on my noise floor.
So - all good. I think the Apex 460 is a really good platform to build a mid price great mic.
Cheers
September 09, 2020, 08:28:03 AM