Drawmer DS404 Quad Channel Noise Gate
Last Update 06-11-2015
The Drawmer DS404 is a quad channel noise gate with variable frequency
detection. It is designed to improve signal-to-noise ratio of
particularly noisy signals such as live vocal mics or the neighboring
on the toms of a drum kit. When I bought this one off the bay,
its operation was sporatic. I eventually uncovered a flaky power
rail that was caused by a bad capacitor following the bridge
rectifier. Beware of buying used music gear on ebay!
The DS404 is a compacted version of its famous brother the DS201.
To conserve panel space some controls were omitted but this is still a
useful device. I'll reach for the DS404 first, and if that
doesn't solve the problem I will reach for the swiss-army-knife
DS201. I have one of each in my studio and this has been an
for space and practicality - six channels of gates, four basic and two
advanced. So far the DS404 has worked quite well for live drums.
Tuning the gate is described on my DS201 page. The
the Attack and Hold controls, but internally these are automatically
set in the DS404 via program-sensitive circuitry. A simplified
version of the HOLD control is offered with the GATING switch offering
hard and soft gating (similar to hard/soft knees of DBX
compressors). Soft gating is optimized for vocals and wind
instruments, while hard gating is optimized for drums. The Range
control is replaced by a switch offering (-)90dB or (-)20dB of
attenuation when the gate is off. (-)20dB works better for live
recording and minimizes "chattering". The DS404 omits the
"ducker" function of the DS201.
Each gate channel can be slaved to the one to the left of it, meaning
that the gating, threshold, and envelope characteristics are controlled
by the "master" to the leftmost channel.
Inputs and outputs are
electronically balanced +4dBu XLR
jacks, no -10dBv 1/4" jacks here.
These boxes do have one achilles heel - the 3-way OUTPUT toggle
lose their contact integrity with age (translated: the audio cuts in
and out, and wiggling the switch handle confirms the fault). I
replace them on my unit. Unfortunately these are a custom switch
available only from Drawmer. They are a two pole switch, but not
on-off-on action - in the center position one pole is shorted to one
throw, but the other pole is shorted to the opposite throw. And
are PC board mounted switches so the replacement must be an exact
They are basically emulating the action of 3-way slideswitches.
bloody unlikely (Drawmer is british, mind you) to find these switches
on any low quantity electronic supply vendor because of their custom
operation, and I can't find ANY OEM marking on the case of these
things. So Drawmer referred me to an authorized service center
the states, which quoted me US$18 PER SWITCH. This device has
four total, adding to US$72 not including shipping and tax.
Disassembly to get
to these switches is a bit of a PITA in that you have to disassemble
the front panel (including all knobs and mounting nuts/washers), then
you have to spread the sides of the case to get the switch assembly
clear of the unit. Not fun...