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Speck ASC Four-Band Parametric EQ

They say "Good things come in small packages," and this is certainly true of the diminutive Speck Electronics Model ASC four-band parametric equalizer ($645).

They say “Good things come in small packages,” and this is certainly true of the diminutive Speck Electronics Model ASC four-band parametric equalizer ($645). Offering a single channel with hybrid topology of a simulated inductor for the low and high filters and two true parametric low/mid-range bands, this unassuming half-rack handful puts powerful tone contouring in your toolbox.
Product PointsApplications: Studio, broadcast, location recording, commercial installations

Key Features: Hybrid of simulated inductance and fully parametric equalizing circuits

Price: $645

Contact: Speck Electronics at 760-723-4281 Web Site


+ Musical sounding tone contouring

+ Compact size

+ Modest price


– No rack ears

– Requires optional shelf to rackmount

The Score: Speck Electronics’ ASC four-band parametric EQ provides excellent design and sturdy construction at a reasonable price.

An input level master control provides -12 to +6 dB adjustment to accommodate both pro and consumer levels. The simulated inductance (SI) design on the low and high bands is similar to those found on highly prized Pultec EQs. There is no Q control on these filters, although the low tone control does provide a shelf/peak option. The ASC offers 15 dB of boost/cut control for all four bands; midrange controls are 40 to 800 Hz or 400 Hz to 8 kHz (pushbutton selector) and 400 to 10 kHz fully parametric bands with Q control fills.

Inputs are balanced XLR and TRS 1/4″; my version also sported a transformer-coupled XLR output as well as an active balanced 1/4″ TRS output. The transformer tends to saturate at low frequencies, potentially “softening” the sound, a potentially valuable commodity in this digital age. Since a transformer floats above ground, it also reduces the potential for ground loops and EMI/RFI pickup.

You can get the Speck Electronics ASC without the transformer for about $100 less – it is all up to your romantic concept of a transformer that makes it a worthwhile option, according to Vince Poulos, owner and designer.

I found its rather severe, almost military-styled gray silk-screened faceplate a curiosity considering the current vogue of iridescent red, blue and purple found on much of the new peripheral equipment and virtual plug-ins.

I took the ASC up to NPR’s shop for a peek under the hood, where I found straightforward engineering; precise board work and quality parts. Power is provided by an external supply, the connection made by a nonlocking keyed Molex connector. The top of the steel case wraps around the back, providing good protection from dust and spillage, and the XLR connectors are screwed to this folded-over backplate. Additionally, each sealed 9mm boost/cut and input gain control offers a center detent position. The pushbuttons, LEDs and TRS jacks float off the circuit board.

In use

At NPR, reports are recorded from a variety of sources. EQ is an essential tool that we employ radically when necessary. News spots are especially challenging when the reporter is in a studio using a condenser microphone and the “actuality” (quote from a newsmaker or an expert in the field) is recorded over a satellite phone from space. We have to blend these extremely different fidelities so they flow together.

I took the Speck Electronics device into Studio 2C, home of the hourly NPR newscasts, and assembled several difficult spots with it. It is very effective on dull, ugly phone-ins, warming up the low end while simultaneously brightening overall without that harsh, peaky edge I hear so often on the radio.

I then used it on a tubby ISDN feed, and convincingly matched our guest’s voice with the U-87 “in-house” clarity of Noah Adams’ voice, host of NPR’s “All Things Considered.” This matching is important to give radio listeners the illusion that the conversationalists are physically together in the same room. The ASC equalizer is very transparent and effective on spoken voice.

Transmission whines are another common problem; these pure tones get picked up somewhere between the source and the studio and require extremely steep notching to remove them without damaging the overall frequency content. The ASC was not able to counter a 7 kHz sing effectively. I don’t fault the equalizer for this, however, as it never claimed to be a notch filter.

Okay, on to the raison d’ĂȘtre, music! There was only one ASC four-band parametric available to me, so I miked up our Camco studio drum kit and applied the equalizer drum by drum. Boy howdy, does it bring the thumps and thuds to life. I often double-mic the bass drum with a Shure Beta 52 on the audience-side head and a Beta 96 on the drummer’s-side head, carefully accommodating phase and fat. With the little Speck equalizer I was able to put such a convincing peak attack on the Beta 52 that it made the drummer’s side microphone unnecessary. That is what I want from my tools – the sound I like without the work.

I use Pinstripe heads on the toms (a single-membrane center surrounded by oil-filled double membranes that attach to the tone ring); they are bright and clear, but not much oomph in the low end. Here is where the ASC really shines. The SI low-frequency shelf adds depth and power to the toms without making them sound boxy. You can get ridiculous with the amount of low end you add – full tone springs out of the drum.

On bass guitar: again, huge amounts of rich, low end can be added without the instrument losing distinction. While this band does not offer a Q control, the shelf/peak selection worked just fine to achieve the necessary change.

Lastly, I used the four-band EQ as a mastering tool on a summed stereo mix (remember, I only had one unit). The half-rack device really works splendidly as an overall tone modifier. The generous ceiling of 25 kHz can provide an exciter-like effect without the distortion. With midrange offering full Q and parametric controls, I was able to gently tailor the mix into the clarity I sought. And the low-end SI control warmed things up in the most musical way.


The Speck Electronics Four-Band Parametric Equalizer provides a blend of circuits that would conventionally take up huge rack-space real estate and create huge empty spaces in your bank account. Useful in all the audio applications I tried, the ASC proved to be an indispensable tool.