Shure ILP-1 Questions

[sr1200]

I have a pair of sm98s that I LOVE on toms. One of the pres has been acting a little wonky lately. I found the schematic (LINKED). There are 2 symbols ive never seen before and perhaps someone can chime and explain wth those are (L1/2 all the way to the right, before the XLR out) and D1Q1 looks like a pair of diodes but not quite?). In addition, i would love to clone these and make a more serviceable box to plug the mic's into, but i can't seem to find a 183A01 (all i could find on it is that its a PNP, SOT23 (MMBT5087)) if theres something equivalent. Apparently shure makes a "newer" version of this amp, but its not exactly made FOR this mic (but shure claims it works just fine). I dont want the sound to change on these guys to any great degree. If anyone has suggestions, im all ears.

LINK TO SCHEMATIC

 

[mad.ax]

-L1/L2. This is the standard graphic symbol for ferrite bead.

-D1Q1. MMBD2838 is a double diode. Obviously they use only a single diode here, hence the strange look.

-MMBT5087 is available at digikey.

 

[sr1200]

thanks for the insight. Why use a double diode if you're only using one? (out of curiosity) was all they had at the time instock? lol something along those lines?

 

[mad.ax]

My guess is it's a production line optimization mater... They must have that double diode loaded on their pick'n'place machine, and it's cheaper to waste half of a double diode rather than load another reel with a single diode....