My Favorite Waste of Time . . .

[MicMaven]

Occasionally, when I cannot sleep, I find myself in the workshop making something I don’t need, but it is good therapy and takes my mind off matters keeping me awake. I am retired and, while do not miss my old job, I do miss being productive.

Handheld Condenser Project No. 62024B -

This model is constructed with a new, unmarked $14 Shure Beta 57a microphone handle, a $3 grill, an electret circuit board, and $10 condenser capsule, all purchased on eBay.com sometime ago and just collecting dust in my parts closet. The capsule mount is a hand-cut PVC pipe fitting shaped to suit the purpose. The capsule is mounted on toothpicks set in holes I drilled in the PVC bit, affixed for all time with with excessive globs of CA glue. The last image depicts one of my little watchmaking desk vices which are very useful in this type of project. Every man needs at least one vice, eh?

That’s it. Nothing fancy and certainly no big deal, but it sounds OK and provides a low cost, yet effective, microphone with computer speech recognition software and (with 10dB attenuation) with an amateur radio transceiver. The photos tell the rest of the story. As always, it is gratifying to enjoy that sweet sense of personal satisfaction derived from a successful home-brewed project. A man needs a hobby, right? // James

(PS - I cannot decide which grille I like better. )

 

[pmfalcman]

Toothpicks! Of course! Great, simple solution.

I've been toying with an idea of making front address mics in BM-800 bodies. And for lamentable lack of a 3D printer I was dreaming up some complicated constructions.
Silly me. Toothpicks, matches - ready-made, slightly vibration dampening supports.
Thank you

 

[MicMaven]

Toothpicks! Of course! Great, simple solution. ........Toothpicks, matches - ready-made, slightly vibration dampening supports. Thank you

I have a similar notion of using stiff wire, like stiff 12 or 14 gauge copper wire and drilling holes in the base and a PVC ring, which would be more stiff and secure.

Another notion I once used was a foam foot made from a lavalier size pop filter. I ran the wires from the capsule to the board through the foam and let the capsule sort of float in the middle of the head basket. Worked a treat. See photos.

I made an end-address model with a bit of flat aluminum bar stock and a 25mm PVC pipe hanger that can be glued or screwed to the bar stock. This works well and can be sized to fit the space. See Photos.

Crazy, eh? Thanks for the kind words - James.

 

[pmfalcman]

Same here with wires. But only as an (abandoned) idea - I wanted something that dampens vibrations. Or at least does not conduct them as metal does. So toothpicks/matches feel better.
Set in large holes, in a rubbery base, filled with silicone, for additional dampening.

The PVC clamp is great too!
Funny I didn't think of it having already used such clamps to hold my mics on a lenght of a tree stump in "tree ears" array. And for other, experimental placements. And to hold my OPICs in BM-700 bodies (large clamps) in ORTF array. Mainly ORTF, that is, for they can easily be rotated to different positionings.
Piece of 20x30 mm, two drilled holes, two screws, two large pipe clamps, washers and you have a very flexible mic mount. Stiff but flexible
Lousy dampening though. But I found a solution for this - I don't kick the stand. Works like a charm.

Crazy? Naah

 

[k brown]

Toothpicks!

Great minds . . .

 

[rock soderstrom]

The PVC clamp is great too!

 

[k brown]

View attachment 140632

I agree it's handy, but way too much surface area in the immediate vicinity of the diaphragm for my money.

 

[rock soderstrom]

I agree it's handy, but way too much surface area in the immediate vicinity of the diaphragm for my money.

I think you're right. On the other hand, you often see in microphones with smaller capsules that the front boundary surface is deliberately enlarged with various constructions.



What are the specific influences on the acoustics caused by these disks? What happens as a result? Changes in the recording of lower frequencies (analogous to a baffle for a free standing loudspeaker)? Does the directional characteristic change from cardioid to rather omnidirectional? Comb filter effects that negatively influence the frequency response?

We've discussed it a bit in this thread before, but it's not really clear to me yet.

Just be aware that this thick material effectively increases the diameter of the capsule, delaying the time it takes the sound to travel around the capsule, changing the sound.

 

[k brown]

The rings create a boundary effect at frequencies above those determined by the diameter of the ring; that is, from that frequency on up the output is increased about 3-5dB or so and it becomes more directional at those frequencies.

It's a less elegent way of doing what the sphere (APE) does in the Neumann M 50, but with significant diffraction effects from the edge of the ring. Also these rings affect freqs about an octave higher than the 40mm sphere of the M 50.

Attached is a full article on the Schoeps V4U, which shows the effect of such a ring on a cardioid capsule (they were usually used on omnis). A full sphere can't be used on cards, for obvious reasons.

And the thread on my DIY approximation:
https://groupdiy.com/threads/cool-use-for-primo-em200-204.78994/

 

[rogs]

When it comes to end address in BM800 body..... I've used toothpicks - or more accurately 'cuticle sticks' - and sleeved them with heat shrink for mounting those cheap (but really quite good ! ) 25mm electrets.
I also created some 'mounting rings' using rubber bands - slightly tensioned and super glued. I wasn't sure how long the super glue might last, but I have one that is 4 years old and it seems fine. I think super glue (is that 'krazy glue' in the US?) works really well with rubber anyway....

For LDC end address in a BM800 I use a custom 3D mount (stl files here: https://www.thingiverse.com/thing:3085428 - really cheap 3D printed mounts from here: https://jlc3dp.com )

 

[MicMaven]

I wanted something that dampens vibrations. Or at least does not conduct them as metal does. So toothpicks/matches feel better.

Funny I didn't think of it having already used such clamps to hold my mics on a length of a tree stump

Ha! Good idea using pipe hangers as mic holders in the field! You could use a larger size and wrap the mic bodies with packing foam or silicone or rubber sheeting to dampen vibration, although I concede not kicking the log probably works best, as you suggest.


FLASH - I just remembered I once used hollow plastic stems from cotton swabs instead of toothpicks. These worked just as well as the toothpicks. (See photos)

BUT the FOAM lavalier pop filters WORKS BEST BY suspending the capsule and isolating it from handling vibration on a "cushion of air." I suspect one could use more or less foam depending on the mass of the capsule.​

James

 

[rock soderstrom]

The rings create a boundary effect at frequencies above those determined by the diameter of the ring; that is, from that frequency on up the output is increased about 3-5dB or so and it becomes more directional at those frequencies.

It's a less elegent way of doing what the sphere (APE) does in the Neumann M 50, but with significant diffraction effects from the edge of the ring. Also these rings affect freqs about an octave higher than the 40mm sphere of the M 50.

Attached is a full article on the Schoeps V4U, which shows the effect of such a ring on a cardioid capsule (they were usually used on omnis). A full sphere can't be used on cards, for obvious reasons.

And the thread on my DIY approximation:
https://groupdiy.com/threads/cool-use-for-primo-em200-204.78994/

Thank you!!

 

[rock soderstrom]

When it comes to end address in BM800 body..... I've used toothpicks - or more accurately 'cuticle sticks' - and sleeved them with heat shrink for mounting those cheap (but really quite good ! ) 25mm electrets.
I also created some 'mounting rings' using rubber bands - slightly tensioned and super glued. I wasn't sure how long the super glue might last, but I have one that is 4 years old and it seems fine. I think super glue (is that 'krazy glue' in the US?) works really well with rubber anyway....

For LDC end address in a BM800 I use a custom 3D mount (stl files here: https://www.thingiverse.com/thing:3085428 - really cheap 3D printed mounts from here: https://jlc3dp.com )

View attachment 140646View attachment 140647

Cool stuff, one reason more to buy a 3D printer.

 

[k brown]

The best 'object' behind a cardioid capsule is a cone or hemisphere, as seen in countless commercial products (sometimes with a ring of foam on top of it). These shapes produce no edge diffraction.

These can easily be DIY'd with almost any moldable material; modeling clay, orthodontic wax, etc. My favorite is the stuff I've posted about in several threads: Coax-Seal. https://www.amazon.com/Fittings-Universal-Waterproof-Non-Conducting-Wire/dp/B00UZWM1U0/ref=sr_1_2?crid=2R65N4S5JL34P&dib=eyJ2IjoiMSJ9.IPIKWKc3z_WoSmw1Kh6acgHUBz7UuVzakZFNg5f4Q5g629ZxLPYi6r06H1c-fuvo5JT5KSjzCoa6iG010cOc9YD6g1xYk2UvlbB50WSaNob3hoVDvWP7GyZG5z3scR3GxVP1PgY1o6KHbs3Ff671isIG3Jvzy7OIDFFAMlg0wSRIIcI4D9aYeHDxmAWj0qsURuGDUYunvn3sPuo2RXAio2QgFA2rpCcbUgV0m3kvi6A.rvcrsfhQzhCr3slgVtKIHgFvb3TnznZNr4dD0J7QW7Q&dib_tag=se&keywords=coax-seal&qid=1732745348&sprefix=coax-seal,aps,282&sr=8-2

It never hardens, is removable, and sticky, so it doesn't have to be glued into place. Simply mold into desired shape with wet fingers.

It's what's under the capsules in the photo in post #5.

Since it has high mass, I also use it to deaden mic bodies.

 

[k brown]

I think you're right. On the other hand, you often see in microphones with smaller capsules that the front boundary surface is deliberately enlarged with various constructions.
View attachment 140637
View attachment 140638

What are the specific influences on the acoustics caused by these disks? What happens as a result? Changes in the recording of lower frequencies (analogous to a baffle for a free standing loudspeaker)? Does the directional characteristic change from cardioid to rather omnidirectional? Comb filter effects that negatively influence the frequency response?

We've discussed it a bit in this thread before, but it's not really clear to me yet.

Here's a graph showing response at different angles, with and w/o the ring (which they call a "shutter"), for the M 221 B capsule shown (M 934 B):

 

[rock soderstrom]

Here's a graph showing response at different angles, with and w/o the ring (which they call a "shutter"), for the M 221 B capsule shown (M 934 B):

Thanks, interesting. The german expression "Umwegscheibe" (detour?? disk) is a pretty accurate (and better) term IMHO.

 

[amplexus]

The best 'object' behind a cardioid capsule is a cone or hemisphere, as seen in countless commercial products (sometimes with a ring of foam on top of it). These shapes produce no edge diffraction.

These can easily be DIY'd with almost any moldable material; modeling clay, orthodontic wax, etc. My favorite is the stuff I've posted about in several threads: Coax-Seal. https://www.amazon.com/Fittings-Universal-Waterproof-Non-Conducting-Wire/dp/B00UZWM1U0/ref=sr_1_2?crid=2R65N4S5JL34P&dib=eyJ2IjoiMSJ9.IPIKWKc3z_WoSmw1Kh6acgHUBz7UuVzakZFNg5f4Q5g629ZxLPYi6r06H1c-fuvo5JT5KSjzCoa6iG010cOc9YD6g1xYk2UvlbB50WSaNob3hoVDvWP7GyZG5z3scR3GxVP1PgY1o6KHbs3Ff671isIG3Jvzy7OIDFFAMlg0wSRIIcI4D9aYeHDxmAWj0qsURuGDUYunvn3sPuo2RXAio2QgFA2rpCcbUgV0m3kvi6A.rvcrsfhQzhCr3slgVtKIHgFvb3TnznZNr4dD0J7QW7Q&dib_tag=se&keywords=coax-seal&qid=1732745348&sprefix=coax-seal,aps,282&sr=8-2

It never hardens, is removable, and sticky, so it doesn't have to be glued into place. Simply mold into desired shape with wet fingers.

It's what's under the capsules in the photo in post #5.

Since it has high mass, I also use it to deaden mic bodies.

That looks a lot like a butyl based mastic- i use it to replace the various “seals” around wires in powered speakers that go into the speaker cabinet from the isolated box for the plate amp.

 

[MicMaven]

That looks a lot like a butyl based mastic- i use it to replace the various “seals” around wires

I understand it was originally developed as a moisture seal and sound dampening substance in automobiles to seal doors, windows, and so forth. I purchase it several feet at a time in large spiral rolls for very low cost. I buy in bulk, and split it up between several local ham radio friends. Search for: "Double Sided Butyl Rubber Tape Sealant Mastic Tape Car Van Bus Auto Repair" and it should be cheaper than paying the Coax-Seal company a lot for a little! Just my take. James

 

[13engrsapper]

Thanks, interesting. The german expression "Umwegscheibe" (detour?? disk) is a pretty accurate (and better) term IMHO.

View attachment 140843

Gotta love the German compound words.