Specifications

generally has a really wide bandwidth that couples the
RFI on the power line into the audio circuitry.
Our preamps from the 90’s (the K-1 and K-3) had phono
card options, but to avoid problems with hum had
external power supply boxes. So you end up cutting o
your nose to spite your face, because you still end up
with two boxes.
Now that digital is the dominant source for most
audiophiles, we only oer phono stages as separate
components. The way I gure it, people into turntables
these days are a dedicated bunch and really want to get
the most performance possible. After all a good ‘table,
arm, and cartridge is going to cost at least $2,000 and
more like $5,000 to $20,000 for something really nice.
To make a phono stage in the $1,000 range means it has
to be single-ended only and use IC’s. In my opinion this
won’t give the level of performance that we want to oer
in our products.
" I think that an integrated amp makes the most
sense for combining two functions into one box. "
One could make a case for combining a DAC (ie, a digital
preamp) with an analog preamp and then having a
separate power amp but to me this is much more of
tens of amperes to loudspeakers is not conducive to high
performance. Similarly, putting complex digital circuitry
in the same box with analog circuitry is going to cause
problems. The RFI from the digital circuits is going to
contaminate the analog signals.
" So to my way of thinking the best route to
reducing the overall number of boxes in your
system is an integrated amp (combining the two
analog components into one box) and then a
separate box for the digital (either a disc player
or a DAC). "
But even putting a phono stage into an integrated is
problematic. Although everything in the box is still
purely analog signals, just the problem of having a huge
power transformer for the amp section is going to make
it dicult to avoid introducing hum into a phono stage.
It’s hard enough to put a small, super-shielded power
transformer in the same box as a high-gain phono circuit,
but just about impossible with a huge transformer
required for a power amp.
Toroidal transformers tend to have less stray magnetic
elds than E-I (square) transformers, but in my opinion
they don’t sound as good. A toroidal transformer
t: 01727 865488 e: [e-mail] w: www.symmetry-systems.co.uk
Symmetry, Suite 5, 17 Holywell Hill, St Albans, Hertfordshire AL1 1DT
Page 11
The AX-5 Story
from Ayre Acoustics March 2014