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Introduction
Inspired by the original “Sound of Tomorrow U67,” the U99 is a multi-pattern tube microphone for
the recording studio and for premier live events. Featuring a k67 dual symmetrical backplate dual
membrane capsule along with the signature Soundelux USA “fat” switch featured on the U195
microphone, and an innovative new high frequency “boost-flat-cut” switch, the U99 has enough
proximity effect to sound full, but not so much that it sounds boomy. This makes it a natural on
vocals, acoustic instruments, drums, and VO.
As with all Soundelux USA mics, The U99 uses a “new old stock” tube and true linear high current power supply
for the fullest possible sound. It also features a large core output transformer to radically increase the low
frequency headroom. The mic comes with its own proprietary N470 power supply, six pin XLR cable, and bottom
thread shock mount, and is built in the same facility by the same people who build Bock microphones.
Description
The Soundelux USA Model U99 is a high quality continuously variable directivity studio condenser microphone
utilizing vacuum tube electronics. Modeled after the famous 67 designed and originally built in the 1960’s, this
mic takes that platform and expands the electronics bandwidth and feature set. It utilizes it’s own proprietary
cable and power supply. The microphone’s audio output is standard male XLR3, with positive excitation of the
diaphragm at the front of the mic resulting in a positive voltage at the output XLR’s pin 2. Audio output is fully
transformer balanced.
Additional Circuit Notes
The Soundelux USA U99 uses classic single pentode run as triode circuitry with high quality through hole
components. Through hole components are more mechanically robust than surface mount and allow for worldwide
ease of repair, as well as being the component standard for all vintage mics. Single triode or pentode run as
triode mic circuits demand excellent capsules before them and excellent transformers after them, with a reward
of low noise, simplicity of troubleshooting, and classic sound unachievable otherwise. The Soundelux USA U99
departs from the classic 67 of the 1960’s in its expansion of the bandwidth of the electronics, which has had its
low frequency cutoff frequency decreased from 40 Hz to 10 Hz, without any loss of high frequencies, by use of a
larger transformer.
As well, the cathode self bias cap is rear of mic switch selectable for “fat,” which has an increased value to
maximize warmth, or “normal” with a traditional value capacitor. For loud sound sources, or very close up use, a
-20 dB pad switch is available on the rear of the mic. As well, the rear mounted “High Frequency” switch allows
the user to tailor the desired response at 10 kHz to “flat” (capsule has natural boost of +2 dB @ 10 kHz), “boost”
(+2 additional dB @ 10 kHz, total +4 dB @ 10 kHz, a gentle shelf starting at 4 kHz), or “cut.” Cut has two corner
frequencies, 10 kHz and 5 kHz, and reduce the sibilant region 3.5 kHz - 8 kHz by 1.5 and 3 dB respectively.
Getting Started
It is recommended that the user place the mic in its shockmount on a stand and connect all the cables before
applying power to the unit. Allow a few minutes for the mic to warm up.
Soundelux Model U99
User Manual