I own two Heiserman H47tube mics and faced a similar issue with the second kit. See my posts on this thread from 17th November 2021 & 29th November 2021. Here is an excerpt from the latter:

"Subsequently, Matt shipped me a long 3/32" hex driver to check/tighten the PCB screws and some foam insulation tape with which to line the inside of the lid. The PCB screws did not need tightening, though I did give the other screws just a wee bit more torque. And I only applied a small square of the foam insulation tape between the bottom lid screws on each side.

Now it is quieter than the first kit's power supply. . .which is pretty quiet."

Of course, you want to unplug power and be extremely careful : High Voltage and a capacitor that holds it.


Kind regards,

Ray H.

Good to know it was addressed for you (even if it involved you doing some work on it yourself). Still I am kind of wondering if other brands have the issue as often , or ever. My nuemann power supply is dead silent sits on my desktop. Plus as soon as I came to the forum I found others with same issue. I do like the mic sound (alot) but if I knew another brand sounded close and did not have the issue I would swap it. Seems like a qc issue.

Hit up Heiserman. They replaced the transformer in mine with a toroidal transformer (which I think they ship the new ones with) and it's dead silent!

I've tried to express a desire for more (what I would classify as) qc from the firm; but I don't know how it is received. . .other than their gracious responses on this forum.

My conclusion: They just have their own way of building great microphones that seems vastly different from Neumanns or Schoeps (the latter is my favorite microphone manufacturer on the planet). But, they clearly have put a lot of love, attention, and mojo into their work. The 'fix' for noisy power supplies is trivial. And expect to replace tubes.

That said, I absolutely love my Heiserman H47tube mics. I won't be swapping them.


Best wishes,

Ray H.

I understand, hopefully they will chime in here then. I sent unrelated emails a month ago with no reply + read others on gearspace mention time delay issues.

So I understand your other comment Schoeps has great quality but they don't make any mics targeted at cloning 47s correct?

When did that occur? Did you just email them and send it in for them to work on?

No, they don't.

My feelings about mics are very far from the mean expressed here on GS. However, I do find great 47s worthwhile: especially for the performances they inspire—more than just the cloning of originalist 47 sound. It is an explicitly emotional connection. Heiserman sticks the landing for me across the board.

Schoeps sticks the landing on a different gymnastic. However, run it into an 2BA-221 to add some mojo, ingest that through a compelling channel strip like the Grace m103, tweak it around a bit. . .

Had they not been the recordist, I don't know how many people would be able to blindly tell you which is which in the context of listening to an even moderately orchestrated / arranged tune, simply from the sound? Far fewer than will admit so here.

Still, my preference is for a deep mic locker full of high-end mics. . .lots and lots of Schoeps, a couple Heiserman H47tubes, plus a collection of other wonderful choices.

I'm hoping you will come to love your Heiserman as much as I love mine.

Ray H.

Interesting you mention the 2BA-221 I have looked at that and thought it would be fun to try out (the blend knob intrigued me), very sparse to none reviews though...kind of like the Everest

Are there direct comparisons between the Wunder Cm7 and the H47?