Have just got an Inote Millenium DI box. It seems to work OK, but I'm puzzled by the instr/spkr switch. In spkr position it gives an extra 40dB attenuation plus some hf roll-off (100k/47nF). I understand the attenuation, although it seems a bit excessive, but why the hf cut?
Can't see why you'd want the HF rolloff...
My quick calculation suggests that makes it 6dB down at 33Hz - which can't be right! Would someone like to correct my sums?😕
My quick calculation suggests that makes it 6dB down at 33Hz - which can't be right! Would someone like to correct my sums?😕
I don't know what a DI box is.
The 40dB cut when in speaker position seems like it is designed to accept a line level signal without attenuation (or very little) and when the input is from a speaker, then the extra 40dB (divide by 100) brings the speaker level signal back down to near line level.
A series 100k followed by a 47nF to ground is a Low Pass Filter with F-3dB=34Hz.
It attenuates the bulk of the audio signal at a rate of 6dB per octave.
A series 47nF followed by a 100k to ground is a High Pass Filter with F-3dB=34Hz.
This passes most of the audio signal and blocks both sub bass and DC signals.
You need to tell us what you have, not making us guess.
The 40dB cut when in speaker position seems like it is designed to accept a line level signal without attenuation (or very little) and when the input is from a speaker, then the extra 40dB (divide by 100) brings the speaker level signal back down to near line level.
A series 100k followed by a 47nF to ground is a Low Pass Filter with F-3dB=34Hz.
It attenuates the bulk of the audio signal at a rate of 6dB per octave.
A series 47nF followed by a 100k to ground is a High Pass Filter with F-3dB=34Hz.
This passes most of the audio signal and blocks both sub bass and DC signals.
You need to tell us what you have, not making us guess.
It's a passive input device for musical systems. The following is a discription of one unit:
Passive direct box for connection of unbalanced musical instruments, line level sources and guitar amplifier outputs to Low-Z balanced microphone input for PA or recording. 1/4" (6.35mm) input (with parallel 1/4" (6.35mm) output); switches for speaker/line-level attenuation; high cut filter and ground lift; male XLR type balanced output. Uses DBT-1 transformer (20K/150 Ohms).
Passive direct box for connection of unbalanced musical instruments, line level sources and guitar amplifier outputs to Low-Z balanced microphone input for PA or recording. 1/4" (6.35mm) input (with parallel 1/4" (6.35mm) output); switches for speaker/line-level attenuation; high cut filter and ground lift; male XLR type balanced output. Uses DBT-1 transformer (20K/150 Ohms).
Sorry I was a bit sketchy about the attenuator. It's a series 100k with a shunt of 1k resistor and a 47nF in parallel forming a low pass filter (all before the transformer). The series resistor is switched to 1k in the "Instr" switch position.
I think the performance is complicated by the transformer load as the cut off seems to start around 100~200Hz.
I think the performance is complicated by the transformer load as the cut off seems to start around 100~200Hz.
- Status
- Not open for further replies.