Replaced the 1/2" polycarb with 3/4" acrylic and the mud went away. I think that the poly bib was resonant in the low mid frequencies. The big problem is going to be supporting this thing- it's fairly heavy.
Now, a clear top for the bib.
Not acrylic- polycarb. Polycarbonate was available as 1/2" thick material, and I wanted to try something lighter than acrylic. It's a beautiful look, I think. Sit in chair, play guitar, and hey, you can see your fingers through the bib!
The guitar PZM mic (near) is being held in place on the underside with magnets. Powerful magnets- magnets that will hurt if they snap together accidentally and pinch your fingers. There is a technique to using them... like, only ever move one pair at a time, and always keep them mated, even if it's only temporarily. A loose magnet will find the one you're holding.
This view is looking down from the other end. You can see the stand and the bars that support the top. I thought they were stainless steel, but the magnets say otherwise.
So great! I can adjust the locations of each mic, I can see what's going on under the bib. I made seven more recordings of The Great Ticking Heart adjusting the mic locations, which mic was on guitar and which on voice, which power supply was used on the new mic, and even which way the bib was set on the support bars. The results?
Not so good. There was excellent rejection of the voice in the guitar mic, but try as I might, I could not get the same isolation on the vocal mic. The guitar always leaked through, even with baffles set up close to the bib.
There was also a change in the quality of the sound of the mics- they sounded muddier than they were with the plywood bib. I can only conclude that 1/2" polycarb makes a poor bib. So... 3/4" acrylic?
I also need to eliminate the support bars- they get in the way of mic placement, and small changes in mic location are making a big difference. I also want to be able to swing the bib away from the player when they need to stand, so there has to be a hinge of some sort. The coyote might call Acme.
The new mic inspired me to take inventory.
Here's the working mics in the Steam Powered Studio mic cabinet:
Crown PZM-30FS, silver, 5”x6”
Crown PZM-6LPB black, 2.5”x3”
Crown PZM-31S, silver, 5”x6”
AKG C2000b (LDC)
AKG C3000 (LDC)
AKG Perception 420 (LDC)
Audio-technica AT825 stereo
Audio-technica AT4033A (LDC)
3x Audio-technica AT4041 (SDC)
Audio-technica AT4049 (SDC)
Audio-technica PRO 37 (SDC)
Audio-technica ATM73M (headset mic)
Audix SCX-one (SDC)
Crown CM-700 (SDC)
ElectroVoice EV-200 (SDC)
ElectroVoice RE1000 (LDC)
M-Audio Solaris (LDC)
MiLab DC96B (rectangular)
MiLab LSR 3000 (end address)
MXL 990 (LDC)
MXL 990 USB (LDC)
Rode NT1-A (LDC)
Sony C37A (MDC)
Beyer Dynamic M420N (c)
Beyer Dynamic M88 TG
2x Peavey PMH
Shure Beta 58
3x Shure SM 57
2x Sony MTL F-96
2x Beyer Dynamic M160N(c)
It's an oddball collection, with some valuable mics and some rare ones, as well as cheapo and common ones. The Peaveys and the Sonys and the Astatic have been around since the Cat Ranch.
And today the package arrived! I rigged up a new version of the bib to support the second large pzm mic for some tests.
This hacked-together support works pretty well, and by leaning in I'm getting even better separation between the vocal mic (red star) and guitar mic (blue star).
Looking very serious here, so you can see how this works.
The green star is showing the power supplies for the newer (older) pzm mic. One is an active supply, using transisters to boost the voltage of the phantom power, and one uses a transformer. There's a big difference in sound between the two, allowing for fun options!
Next- an acrylic bib???
A perk where I work is scrapping. This little item showed up in a recycling bin last week. At the least I'll turn it into a table, but it's more likely to be the base for the singer/songwriter bib I want to make.
These "casters" also showed up in the bin. They're actually meant to be used as load bearing bearings, but what's most interesting about them is that they can wobble to the left or the right. When bolted on the bottom of the thing above, the wobble bearings let the whole assembly roll and turn a little- just enough, as it turns out- without the instability of using swiveling casters.
Another option for the thing is to use it as a base for a boom microphone, one that can be used as a drum overhead. The "real" booms are pricy-
-but I don't need quite that much extension!