JMK Audio are now using the SonicImageryLabs 990Enh Op Amp.
JM-130/JM-530 Features not found on most other mic pres:
Very high Input headroom: for a very wide Dynamic range, ov
er 131dB for the JM-130, >128dB for the JM-530.
The Pad is on the output: this has several advantages; One it does not affect the loading and sound on the mic, Two; Since No DC voltage goes thru the switch (Phantom) like most Mic pre pad circuits on other mic pres there is NO pop when the switch is engaged. Third; being on the output allows the output transformer to be driven harder for a warmer sound.
(JM-530) Added Brass thumb screw to aid in removal or installation of JM-530 Module into Lunch Box. (See Bottom Picture)
The Phantom switch: the phantom voltage ramps up to reduce the pop when powering a Condenser mic.
All switches on both the JM-130 & JM-530 are the large Gold plated switch, to provide very long life and improve the clarity of the signal path, and greatly reduce the probability of noise and static.
Jensen JT-16B Input Transformer
Very high headroom & Wide Dynamic Range
Input Impedance: 1.6K @ 1Khz
Output Transformer Option: Nickel or Steel
Hand wired point to point
THD+N: .006% @50dB Gain @ 1Khz
.025% @-5dB In @ 50Hz
.044% @ +5dB In @ 50Hz
.0125% @ 0dB Input @ 100 Hz
.025% @ +10dB Input @100Hz
.007% @-10dB Input @15Khz
990 Op Amp Slew Rate: 18Vus @ 150 Ohm Load
Frequency response: +- 1dB 10hz to 170khz ; +-.25dB 10 to 50Khz
Max Gain: -3dB @174Khz.
990 Op Amp Only: +-1dB 5Hz to 500Khz
Output clips at +32dBu
CMRR: 117dB @ 60Hz, 85dB @ 3Khz
E.I.N. Noise: -128.5dB w/ 20 to 20kHz filter w/150 ohm load @62dB Gain
-127dB W/20 to 20KHz Filter W/300 ohm load @62dB Gain
Dynamic Range: >128dB; 20 to 20KHz filter w/150 ohm load @ min gain
> 105dB; 20 to 20KHz filter w/150 ohm load max gain
Maximum Input: +8dBu
Hand selected .1% Phantom Resistors
Pad: 8dB on output, enabling the output transformer to be driven harder.
Phantom switching: voltage ramps up to reduce popping with condenser mics.
Laser Engraved lettering, letters will not wear off.
Note: 20 to 20 kHz filter used; -10dB @ 38 Hz & 32 KHz, -20dB @ 90 KHz
Far wider than the typical Brick wall filter, which is -20dB @36Khz