JT30 - Astatic / Hohner Bluesblaster

The Astatic is like Shure a forefather of handheld microphones, also as common and available in many different variants. I like the slightly slimmer shape and the shiny grill. I do not want to and can not go into the production history, only a few basic information. The older models often have a Switchcraft connector behind the front potentiometer. The newer, produced by Hohner (Blue Blaster / JT30 VC) have an XLR connector in the front and the potentiometer behind. More practical is the new form.


The inner life

In JT30 types, basically crystal capsules (later piezoceramic) are installed. Especially the crystal capsules are sensitive to shock and moisture, so that old capsules are usually broken.

In principle it can be divided into two groups: the old Astatic MC127/MC152 capsules and the new Hohner "Japan" capsules. About sound differences, I do not want to say anything here, these microphones are more quiet and acoustical as the Green Bullets and have a strong scattering. Thus, a 3 € Japan element can sound "better" than an "original Astatic" that currently costs 193 € at the TAD.

Potentiometer problems

In the old Astatic a 500k log potentiometer is installed. This is too little for a piezoelectric crystal (ceramics), because it can only produce minimal currents. The signal is weakened.

Later, Hohner installed a 5M log, which provides much better service here. This potentiometer is not so easy to get. I know of no source, especially since it still needs to have a long shaft.

If you install a capsule from Shure now (as many do), then 5M log is inappropriate again. In this case, a 300k lin tone potentiometer by Gibson is recommended. This is an old value, perhaps from the P90 guitars. Do not be afraid because of the linear curve, the regulation is perfect.

XLR wiring

The Hohner can not operate with the "normal XLR to jack", because the assignment is different. But that is quickly changed.

First, remove the Hohner sticker. Now turn the visible screw DOWNWARD to open! Then pull the plug with a small pair of pliers on a pin from the housing. The red cable must be resoldered, see the result in the image.

JT30 with CM capsule

The solution JT30 housing and shure capsule is a very common one, many people have such a microphone. For years my reference.