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Tascam PE40

Parametric EQ By Paul White
Published January 1994

A parametric EQ might seem like a bit of a peripheral purchase, but with its flexibility and fine control, it has a host of creative and corrective applications in the studio. Tascam's 4‑channel PE40 scores for value, but how does it perform? Paul White finds out.

There are times when the fine EQ control offered by a parametric equaliser — so called because it is an equaliser on which all necessary parameters may be equalised — can be indispensable. But what exactly are the 'necessary parameters'? There are three in all: a conventional mid‑price mixing console might be fitted with a sweep mid EQ, which provides us with two of the three parameters straight away: frequency and gain. The frequency control sets the area of the audio spectrum in which the equaliser will operate, while the gain control is used to apply either cut or boost over that range. The range of frequencies covered by a sweep EQ (known as the bandwidth) may be wide or narrow, depending on the design, but the essential feature of a basic sweep equaliser is that, whatever the bandwidth, it can't be varied by the user. And there's our third parameter, because the true parametric equaliser allows the user full control over bandwidth.

The PE40

The Tascam equaliser under review comprises four separate audio channels, each of which has four parametric filters covering the High, Upper Mid, Lower Mid and Low end of the audio spectrum. Despite the profusion of controls, the box is only 2U deep, so to prevent the layout becoming too cramped, a dual‑concentric control is used to access both the Frequency and Q parameters, with a single control being used for the Gain; although it looks as though there are only eight knobs per channel, there are really 12 controls.

Unusually, the input and output connectors are on unbalanced phonos (‑10dBv) and a second phono connector is wired in parallel with each input and output socket to facilitate signal splitting in more complex systems. The unit is powered directly from the mains, and a large power button is located towards the right of the front panel.

The equaliser controls are arranged in two rows, with the Low and Low Mid on the top row and the High Mid and High on the bottom. There is a certain amount of overlap between the filter ranges, which are:

  • Low 40Hz‑800Hz
  • Low Mid 200Hz‑4kHz
  • High Mid 500Hz‑10kHz
  • High 800Hz‑6kHz.

The inner section of the dual concentric control sets the filter frequency, while the outer ring sets the Q. Unfortunately, there are no interim frequency markings so the filters must be set entirely by ear.

The PE40's Q is variable from 1.1 to 5 which, in subjective terms, means that it goes from a broad, subtle curve to a sharp, almost resonant characteristic. All the filter bands offer up to 15dB of cut or boost, and it is possible to set adjacent bands to the same frequency within their overlap range to get even more boost or cut. Applying excessive boost at one frequency may well cause the equaliser to run out of headroom and clip if the input signal level is high, but it can be useful to apply severe cut to reduce the effect of buzz, hum or other fixed frequency interference.

Each of the four parametric equaliser channels may be bypassed using the Bypass switch, but there is no bypass for each individual frequency band, which might have been useful when setting up.

All Things Being Equal...

For the newcomer to parametric EQ, the main problem is evaluating the effect of a new filter setting, which is harder than you might imagine, especially as you can't bypass individual frequency bands. Nevertheless, with a little practice, you soon develop a technique. I tend to set the filters to a fairly high Q and maximum boost in order to find the area of the spectrum that needs treating, and then when this is located, I back off the gain and readjust the Q until I've achieved the desired effect. High Q values are not a good idea for setting mid‑range boosts, but they can be useful at the extremes for bringing out bass drums or hi‑hats. In the mid‑range, lower Qs sound more natural — unless you want to apply cut at a specific frequency, in which case higher Qs are fine.

Electronically, the PE40 works very well and has a generous amount of headroom, so clipping is unlikely unless you pile on a ridiculous amount of boost. However, the close proximity of the controls makes adjustment a touch fiddly, especially the dual‑concentric controls.


Despite its rather cramped controls, this EQ is fairly easy to set up and is capable of excellent results. I used it on complete mixes to enhance the bass drum, snare and hi‑hats using three of the four filters, and it also works perfectly well on individual voices or instruments. Guitar and bass sounds can be treated quite creatively, while more mundane jobs such as reducing hum or taming the boom of an acoustic guitar are well within its capabilities.

While I wouldn't say a parametric equaliser is an essential studio accessory if you already have a desk with two sweep mids and possibly a spare graphic, it is still without doubt the most flexible and most powerful type of equaliser available. The extra effort involved in finding the best settings for a job is invariably repaid by the results obtained, and while more esoteric sounding parametrics are available, they tend to cost rather more than this one. If you feel you need a parametric equaliser that can handle professional quality jobs yet not cost the earth, this has to be one of the first ones to check out.

Filter Tips

In addition to the PE40's parametric controls, there are also two independent filters per channel. The HPF, or High‑Pass Filter provides a 6dB per octave roll‑off below 160Hz or may be switched to provide an 8dB per octave roll‑off below 60Hz. This is useful in a live situation to attenuate traffic rumble or stage vibration and may also be useful in the studio to minimise the effect of hum or passing traffic on vocals or other miked sound sources.

The other filter is Low Pass, and comes in at 15kHz with a slope of 12dB per octave, making it useful for rolling off hiss or other high frequency problems.

Join The Q

In electrical engineering terms, a filter that has a wide bandwidth is said to have a low 'Q', whereas a filter with a narrow bandwidth has a high Q. In other words, the higher the Q, the more selective the filter. A wah‑wah pedal is simply a sweep filter with a very high Q. As a rule, lower Qs sound more natural when boosting whereas higher Qs are useful when you're cutting.

Do I Need A Parametric?

A parametric equaliser isn't an essential studio purchase if you already have, say, a desk with two sweep mids and possibly a spare graphic, but it is without doubt the most flexible and most powerful type of equaliser available. Because it gives you such fine control over very precise areas of the frequency spectrum, possible uses in the studio are numerous and include:

  • Reducing buzz, hum or other fixed frequency interference; taming boominess on acoustic guitars; reducing unwanted artifacts in sampled drum loops.
  • Enhancing specific instruments or parts in a mix, for example, bass drum, snare and hi‑hats, and vocals.
  • Creative treatment of guitar and bass sounds.


  • Four fully parametric channels with high and low pass filters.
  • Good audio performance.


  • Controls a little cramped.
  • Unbalanced, ‑10dBv audio connections only.


Simple to use, cost‑effective parametric, perfect for when the EQ on your mixing console is insufficiently flexible for the job.