Jun 27th, 2016
The ART SLA-1 is an excellent quality, one rack space, 100 watt per channel amplifier. Although priced inexpensively, it is a well-built, very serviceable design that uses common parts and high-quality connectors and circuit components. The original design is done well out of the box, but we do some small and clever updates to make it a little more audiophile.
The AC switch is wired to double up on the contacts – it will probably never fail now.
A vactrol board (opto limiter) circuit is installed at the gain set resistors of the amp, creating or limiting gain with virtually no amplifier clipping. The signal gain is leveled off nicely, a little like a tube amp just at the onset of potential clipping overload. This also reduces the chance of overloading and burning woofers or tweeters, providing excellent protection for pro studio or audiophile use (or even for use with a guitar amp).
We also do some shielding or repositioning of the power transformer, to reduce any stray hum that may come into the audio circuit. The unit uses a high current toroidial transformer (like many modern designs) and correcting the location of shielding and wiring can reduce hum. We do this for many products, from $1000 amps to $200 preamps.
Also changed is the fan speed, which is reduced to lessen audible fan noise, but still fast enough to cool the circuit.
Finally, we QC check all contacts, connectors, and wattage, sometimes adding another resistor to the bias set resistor to make both channels track exactly the same.
I'm fussy, what can I say. The unit is audiophile-grade quality, but I'm making upgrades for use on the road, in the studio, with guitar and bass rigs, and for home audiophile use. The modification is $88 if your ART SLA1 was purchased from us, and $132 if it was purchased elsewhere. A good value, no doubt.