Manley MONO & DUAL MONO TUBE DIRECT INTERFACE MODELS - Manual (Page 7)

OPERATIONAL NOTES
POWER
It is not recommended that you leave your Tube-Direct Interface permanently switched on. This
only wastes electricity and tube life. Tubes filaments are more fragile when hot. Let it cool.
TUBE LIFE
As with all tubes, their quality degrades with age. This is due to cathode emission, a natural process
found in all tubes. We recommend that you have your unit checked every 4-5 years, depending on
usage. Increased microphony can indicate the need to re-tube. Each channel uses 1 x 12AX7WA.
INPUT EQ SELECT.
One should not conform strictly to the labeling of the inputs, but rather to personal taste. This
control should be called a modified "low frequency roll-off". Guitar amps generally have a fair
amount of low frequency roll-off and we approximate some of this curve on the "GUITAR" settings.
The curves are 6dB per octave and not deep cuts. The "BASS FULL" setting is closest to flat and the
3 dB down points are 12 Hz and 15 kHz. The AMP OUTPUT is EQed.
APPLICATIONS The advantage of DI's over guitar amps, cabinets, and a few mics is that for a
clean tone the DI is easier to set up, cleaner, and leakage is non-existant. The advantage to using
both is sometimes the combination is better than either alone, and if not, you at least have a choice.
With guitars it is a simple way to get a clean track in the control room or if the player has a few toys
then the sound may not be limited to clean or simple. The amp output can be used to feed an amp in
the studio and driving the long cable shouldn't be a problem. With synths - the advantages with the
MANLEY DI is a bit of tube warmth and better grounding and gain options. Some use this DI to
warm up recorded digital tracks. Expect a little high end roll-off and slightly more distortion but this
works on some tracks. To us, the most natural sounds are warmest but to others that brittle distortion
of low-cost (digital) electronics needs some good tube and transformer distortion to sound "warm".
Every studio tech has been asked to build a box that has a knob that allows the DI and
mic to get exactly in phase. It always seems that neither position of a phase switch really is perfect
when combining the mic and DI. You can get close if you delay or track slip the DI by a few
milliseconds. The exact amount of delay is not so easy to determine. This will at least compensate
for the delay of speaker to mic through the air. It will also help for the delay of when power hits the
speaker and when the speaker actually moves. The bad news is that different frequencies may come
off the speaker at slightly different times. The other bad news is that any EQ in the amp, and
resonances in the speaker will change the phase at certain frequencies. The good news is that a delay
or track slip will help if you have the patience. If both sounds were perfectly in phase - there woudn't
be much difference in tone to bother with combining them anyways. The other interesting use of the
delay is that you may find some other setting that combines in a very interesting way.
With Bass Guitars some engineers start off with the DI through just a bit of EQ to even out
the notes and gently through a limiter to smooth it a bit more. The mic signals will be more
drastically EQed and more squashed through another limiter. In mixing it might be worth combining
the tracks before EQ and compressing so that they "gell" together better and levels stay consistant.
Guitars through any DI will probably need EQ and effects but this DI has some EQ to help out.