|
 | A volume control is one necessity that even the
most hair-shirt purist could not forgo. Balance control expendable; tone
controls unnecessary but control over music’s volume - essential. Problem
is that in most applications a potentiometer (variable resistor) will be
used directly in the delicate signal path. This can have potentially
disastrous effects on sound quality.
Nowadays any £500+
amplifier worth its salt should have at least an Alps Blue pot fitted, its
metallised, conductive plastic track offering audible advantages over the
most basic carbon-track variant. But beyond the potentiometer lies the
stepped attenuator.
This uses a multi-way rotary switch with a
'ladder' of high-quality discrete resistors making up its rungs. You move
up and down the ladder to change volume by simply turning the
knob.
Danish Audio Connect makes one such device, their £105 CT1
Audio Attenuator with its 24 steps. We tried their 250kohm version in our
World Audio Design KLPP1 valve line and phono pre-amp as well as in front
of some DPA amplification (although 10kohm would be a more normal value
here).
Hooking up the CT1 instead of a DPA's 50S pre-amplifier
was certainly chucking it in at the deep end as the DPA is already a
seriously good preamp thanks to its extremely high-grade Penny and Giles
pot. Used as a passive volume control and connected directly to DPA's 50S
power amp, there was just about enough volume but we had to use most of
the attenuator's travel.
Our first impression was of a
'stripped-down' sound that initially lead us to think that something was
missing. Further listening showed that the DPA pre, in contrast, was
actually laying a thin veil over the sound.
Another bonus with
the CT1 was an increase in the boogie factor - rhythms had greater
conviction and transients were that bit more precise and snappy. Subtle
details previously overlooked made themselves felt - tonal colours were
more realistic and sound staging that much more focused, with images
firmly located. After this promising start, next up was the
KLPP1.
A few wafts of multi-core flux later and the re-tweaked
KLPP1 was mated up to a Chord SPM 400 power amp for auditioning. One
ability of this attenuator that's very obvious is its truly crystal
clarity. The spaces in a sound stage between the various images were
clearer and more open, as if a fine coating of mush had been peeled off
them. The top end was more extended and a little sweeter, while lower down
bass and midrange had lost some of their slightly tubby cuddliness in
favour of a drier, more detailed character.
The CT1 's
'invisibility' was its finest asset. If you're accustomed to cheaper pots,
you might think the CT1 a touch grey and lean when you first encounter it.
Give its sound a chance to sink in though, and you'll wonder how you never
noticed the blatant colorations of less elevated volume
controls.
There are other claims made for the CT1 by the
manufacturer on top of the purely sonic: increased reliability, lower
distortion and better tracking accuracy between channels. The reliability
factor I am not inclined to question given the superb build quality and
use of gold-plated contacts on precision wafers sourced in Switzerland.
And precise channel matching comes from the high-tolerance surface-mount
Metal Film resistors.
Danish Audio Connect CT1 attenuators are
available in 10kohm, 20kohm, 50kohm, 100kohm and 250kohm values, with a
four-wafer version for balanced audio applications priced at £165 each.
|
HI-FI WORLD MAGAZINE
(SUPPLEMENT),
UK, APRIL 1998
(the above is a 100% reprint
of the original review) |
|
Danish Audio ConnecT
Thailand)
Ltd.
Rm. 1501/3 Ban Chang
Glas Haus Bldg.
1 Sukhumvit
Road Soi 25
Bangkok
10110
Thailand
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