Sensitivity (Gain); Cleaning The Cabinet; The Protection Circuitry; A Second Of Silence - Gamut D200i User Manual

Sensitivity (Gain)

Inside the cabinet, at the top edge of the circuit boards, is a dual piano switch marked -6 dB and
-12 dB. Normally, gain is factory set at -6dB or 29dB total voltage gain.
Your dealer can set them for you, so that you get the best match for your preampli er. To match
a passive "preampli er" like our GamuT control unit, the gain has to be high, so set both switches
to "o ". Some preampli ers also need maximum gain, others have a lot of gain in their output
section and therefore should be used with the -6 dB or -12 dB switch moved away from "o ".
If both switches are moved away from "o ", then the gain is reduced by 14 dB. We recommend
that with 4 Volt sources like our GamuT CD player. Noise levels will be lower. We use switches,
because they can be set precisely identical and will preserve the stereo balance.
The maximum voltage gain of GamuT D200i is 35dB. The GamuT C100, D100, M200 and M250i
also have 35 dB maximum gain, so they will all work together in a bi-amped system.

Cleaning the cabinet

The front panel is made of aluminium. It can be cleaned by using normal mild solvents and clean paper
tissue or cloth. Do not use excessive amounts of solvents, and do not let any of the solvent spill into
the ampli er.
The Brass logopanel is covered with a protective layer.
DO NOT USE ANY BRASS POLISH. You will remove the protective layer.

The protection circuitry

The ideas for the protection circuit come from our professional ampli ers, where it has worked
well since 1982. Due to the rugged MOSFET, we can allow high peak currents , and we only need to
mute the input signal in case of long-term overload.
The protection detects DC errors, high level subsonic signals, longterm ultrasonic signals, high
temperature, and to low impedance loads or short circuits.
If needed, the protection will simply mute the input signal, and if necessary open the output relay.
The relay will normally open only after muting the input signal to avoid relay switching of strong
currents that could corrode the relay contacts.
So in case of i.e. a short circuit the input is muted for a second. Then a 1 millisecond long pulse is
sent out to test again. If the short circuit still is present, it waits a second and tries again, and so on.
One second after the user has removed the faulty cable, the system will quickly remove the muting.
The protection also detects too low impedance loads, and alerts the user by muting for a second.
So the user can be sure to hear only clean non-distorted audio. The normal current limiting and
momentary distortions of the music are avoided in the GamuT D200i power ampli er.

A second of silence

You may experience a second of silence while the music is playing loudly. This is the protection
acting to protect your tweeters. Any ampli er will start to clip the top of the music if you exceed
the maximum power level. Technically, clipping generates a lot of high frequency energy, which
can burn out the tweeters in your loudspeakers. The protection constantly checks the energy
above 20 kHz, which humans do not hear. The distortion is momentarily very high anyway, because
you have exceeded the maximum power, so just reduce the level a bit.
You can also provoke the subsonic protection by playing warped records without using a subsonic
lter. Please check your tonearm/cartridge resonance frequency, which should be about 8-12 Hz
to reduce the e ect of warped records.