Barstow U-47 Mod of Marshall MXL2001

[mtl777diy]

I was finally able to remove the damn screws!  I had to do it differently, though, because my smallest drill bit is not small enough and using a hack saw would hit other parts not intended.  So I used a small xCelite cutter with very sharp blades, positioned the cutter perpendicular to the head of the screw, firmly gripped the screw head with the cutter which cut a little bit into the sides of the screw head, then turned the cutter counterclockwise.  It worked! 

So I see that there are three layers in the headbasket - a coarse mesh outer layer, a fine mesh inner layer, and a coarse mesh inner layer - in that order.  I have removed the coarse mesh inner layer.  Still deciding if I should remove the fine mesh inner layer, too.  There seems to be two opinions on what's best - one layer only or two layers. 

 

[ln76d]

Keep more layers on the back side of headbsket and remove all from the front - if you didn't try you will never know.
You can always reverse headbasket

 

[mtl777diy]

Keep more layers on the back side of headbsket and remove all from the front - if you didn't try you will never know.
You can always reverse headbasket

I think it's hard to put the coarse inner mesh back.  It's a thick gauge and not easy to bend.  But the fine inner mesh is very thin and may be easy to put back, so I'll remove it.

For the back side of the headbasket, I'm not removing any layers at all.

Question: Should I solder the outer mesh to some points on the headbasket frame to make sure that it's connected to ground?

Thanks!

 

[ln76d]

If it's not moving inside the frame, rather you don't need to solder anything.
Rather you will not put i back, thin are the worst
Don't be a chicken, remove both

 

[mtl777diy]

If it's not moving inside the frame, rather you don't need to solder anything.
Rather you will not put i back, thin are the worst
Don't be a chicken, remove both

OK, I will remove both, but why are thin the worst?

 

[Gus]

I am not a fan of removing the inner mesh(s).
They help keep contaminants out
Helps keep the RF out
Microphones often sound better with the mesh in
Also if this is the same Royer circuit as in the tape op article the overall circuits(microphone and power supply) works fine with the China 32mm and the MXL2001 type body

 

[ln76d]

If you don't know how to storage microphone and not using pop filter at close distance it's not big difference in case of contaminants. Am cleaning capsules very often and with inner mesh or without don't make such big difference.
"Helps keep the RF out" - i could also argue here, if the backside have that inner crust it shouldn't make much difference, when overall connection of whole hedbasket is proper.
With backside or even without it - i did this on many microphones, working in really different environments - no one ever had problem with RF.
"Microphones often sound better with the mesh in" - It's a matter of taste, so i can't argue here, but my opinion is:
- best headbasket is no headbasket at all - from sound quality side - of course we can't remove it completely
- painted meshes, especially chinese are worst in case affecting overall tone of microphone
- with K67 which have bumped HF region it makes only more "scratchy" hi mid and hi frequency range (also it's a  flat circuit) so at the end we get that typical chinese sound quality.
(am not the fan of royer mod as also its commercial release as mojave - for me is same league as chinese tube microphones)

There's a difference between Neumann or AKG (except some chinese models) headbaskets for example  and most of chinese headbaskets. All affect sound of microphone, but the serious manufacturers rather know how to make overall good sounding microphone.
For example in C414EB change of inner mesh don't make any pleasant difference - also there isn't any "mojo" in it. With both options it sounds really close and good.

 

[mtl777diy]

I ended up with a corrugated high density rubber foam tape that's used for sealing windows (see picture).  I figured that the corrugation of this material will provide some diffusion.  So I get both absorption and diffusion by using this.

 

[mtl777diy]

Here's the corrugated high density rubber foam tape applied to the frame of the headbasket (see picture).

 

[Khron]

Sealing windows, you say? Isn't that stuff like, really fluffy & lightweight? Since it's usually meant to get compressed to barely nothing...

 

[mtl777diy]

And here's the corrugated high density rubber foam tape applied to the base of the capsule mount (see picture).  The foam tape may look big or thick but that's only because the raised ridges are tall.  Looking from a cross-section, the base of the foam tape is only 1/18" thick and the total thickness including the ridges is 1/8".

Please let me know what you think. 

 

[mtl777diy]

Sealing windows, you say? Isn't that stuff like, really fluffy & lightweight? Since it's usually meant to get compressed to barely nothing...

There are some, like this one I used, that are high density.  When you look at it from the top or sides, you don't see any cells.  You'd have to cut the tape and look at the cross-section with a magnifying glass to see the very tiny cells (these are closed cells, btw) which even then are hardly discernible.

This material is almost like rubber band.  On the package it says, "X-Treme Rubber WeatherSeal".

 

[ln76d]

You really don't have to put it on the saddle plastic base, instead you could put it on the headbasket base from the inside.
If there is space between headbasket base and metal plate bottom saddle base, you can fill it with something.

 

[mtl777diy]

You really don't have to put it on the saddle plastic base, instead you could put it on the headbasket base from the inside.
If there is space between headbasket base and metal plate bottom saddle base, you can fill it with something.

I have a Joly-modded Oktava MK319 and he put the foam on the saddle base.  I'm just copying what Joly did.  I hope it's not wrong. 

 

[ln76d]

Test it

 

[Gus]

There can be issues with plastics

The plasticizer can outgas and coat surfaces

You also need to think about what is in the adhesive

Also check if the material supports bacteria growth

 

[mtl777diy]

Test it

I have tested it and it sounds great! 

BTW, as per your advice, I have added foam tape to the headbasket base from the inside.

Thanks!

 

[mtl777diy]

"Microphones often sound better with the mesh in" - It's a matter of taste, so i can't argue here, but my opinion is:
- best headbasket is no headbasket at all - from sound quality side - of course we can't remove it completely

Could you please tell me more what you noticed about how the mic sound changed when you removed the inner mesh in the mics you modified?  What are your before and after comparisons of the sound?  Like, was there more clarity or articulation after the mesh was removed, did the low end response increase or decrease, etc.?  Did you ever have a need to adjust some electronic component values in the circuit because the mic did not sound right after removing the mesh?

 

[ln76d]

No, i didn't need to change any electronic parts after removing inner mesh.
Never was sounding worse.
To be honest, i don't want to describe difference due to poor translation and i have no "flow" in that type of descriptions.
Audiophiles have best poetry for subjective feelings related with audio equipment
Only difference which you should notice is in high-mid and high frequency area. It doesn't affect low end response.
Check by yourself. Don't screw headbasket, grab microphone (don't touch circuit) for a metal base or body pipe, with other hand grab headbasket. Make voice test and gently take off headbasket. If you will get hum, try to ground yourself to the preamp case (with a wire or bare feet ).  You need to place PSU far away from the microphone.
If you will hear difference between mesh and no mesh at all - with one mesh your final sound should be somewhere in the middle. Don't touch circuit!!!

 

[micaddict]

... especially on bare feet.