R/E/P Community

Please login or register.

Login with username, password and session length
Advanced search  

Pages: [1]   Go Down

Author Topic: C-37A Significant Low End Loss - Headbasket Is The Culprit  (Read 610 times)

Spindrift

  • Newbie
  • *
  • Offline Offline
  • Posts: 9
C-37A Significant Low End Loss - Headbasket Is The Culprit
« on: March 02, 2022, 04:11:22 PM »

I have a pair of C-37As in the 3XXX serial range that came with CP-3 PSUs. I also have another pair of C-37As in the 4XXX serial range that came with CP-3B PSUs.  The newer 4XXX pair have significant low frequency loss. I initially suspected the capsule but after simply swapping the head baskets on the mics, it is abundantly clear that there is significant acoustical blockage present in the head baskets that exhibit low-end loss.

The silk lined head basket makes the mic sound like a completely different model, and not in a good way: more highs and more lows are present in the head basket w/o the silk barrier.

The difference between the head baskets is that the full-sounding and airy ones have had the silk layer removed (or didn’t come with it at all?).  The latter model head baskets have a thick layer of silk installed…which is likely dirty.  I’m considering removing the silk barrier all together but I want to try cleaning the head basket first.

What is the proper way to clean mic head baskets? Sonys and Neumann U87/67 head baskets with rotted foam debris from old WS87 pop filters?

Thanks,
Keith
Logged

gtoledo3

  • Full Member
  • ***
  • Online Online
  • Posts: 119
  • Real Full Name: George Toledo
Re: C-37A Significant Low End Loss - Headbasket Is The Culprit
« Reply #1 on: March 02, 2022, 05:05:39 PM »

The easy way is to put the headbasket in the dishwasher. The problem is that this can sometimes be overly aggressive on any plating. It can often be fine, but you take some slight chance. All the same, you may end up needing to go this route if the debris has worked its way in between where the strands of mesh cross and/or you just can’t seem to get it done with a soft toothbrush.

If you use a toothbrush to clean them, I’d recommend vegetable oil or similar (mineral oil, canola) as the thing to dissolve any foam. It’s much more pleasant to deal with than alcohol or naptha, and I have also found it more effective.

After the basket dries, mildly flex the mesh, give it a flick with your finger, and make sure no foam/silk dust still comes off…that’s how I first discovered how debris can work its way in between mesh strand junctures.

Dawn type dish soap is fine for getting the oil and muck off after brushing, if you go that route.
Logged

Kai

  • Sr. Member
  • ****
  • Online Online
  • Posts: 396
Re: C-37A Significant Low End Loss - Headbasket Is The Culprit
« Reply #2 on: March 03, 2022, 04:02:15 AM »

I would agree, except for the dishwasher, or any kind of soap.
The nickel plating will certainly change its color at least.
Same applies to ultrasonic bath, a great unintentional remover of all type of coatings.

If the debris origins from rotten foam windsceens: hardware stores offer PU-foam solvents.
PU - polyurethane- is what the foam usually is made from.

Finally the oil or solvent can be removed by dripping the whole thing into cheap denaturated alcohol.

Logged

octave

  • Newbie
  • *
  • Offline Offline
  • Posts: 1
  • Real Full Name: Octave Zangs
Re: C-37A Significant Low End Loss - Headbasket Is The Culprit
« Reply #3 on: March 03, 2022, 04:58:52 PM »

Last night, with Keith, we decided to remove the silk of the two C-37As (4xxx serials) and we also did some unscientific measurement with FuzzMeasure to see the difference with and without the silk layer.

Each test is using the same microphone, psu, preamp and speaker, the only variable is the head basket.

Refer to the graph attached, for results:
  • Red curve: Basket with silk
  • Blue curve: Basket with silk removed

As we can see with the silk we start loosing low frequencies as early as ~600Hz. Also we can see a high frequency loss above 8Khz.

After removing the silk (photos attached), the microphones sounds pretty much identical to the earlier serial (3xxx) C-37As.

Does anyone know why Sony decided to starting adding the silk to the head basket around serial ~4000. It is such a drastic change. Is it for wind protection or emphasis on mid frequencies? Also lower frequencies and higher frequencies can be filtered out using the power supply if needed.
Logged

Kai

  • Sr. Member
  • ****
  • Online Online
  • Posts: 396
Re: C-37A Significant Low End Loss - Headbasket Is The Culprit
« Reply #4 on: March 06, 2022, 03:27:21 PM »

This silk looks like someone else - not Sony - has stuffed it in.
It‘s obviously much too thick and dense for the purpose.
And the make looks unprofessional.

Silk away - problem solved!
Logged
Pages: [1]   Go Up
 



Site Hosted By Ashdown Technologies, Inc.

Page created in 0.067 seconds with 21 queries.