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The EQUALIZER model one b has an understated, clear front panel.
The EQUALIZER model one b has an understated, clear front panel.

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Square State Solid State EQUALIZER model one b
By Scott Dorsey
Date: May 2010

The Square State Solid State EQUALIZER model one b is a single-channel 3-band LCR-filter eq with 1/4" TRS balanced I/O. It's the first product from Square State Solid State, a Colorado-based firm that designs and builds its products entirely at its Denver-area workshop.

It's a new take on an old classic design with some serious attempts made to keep the costs down. Engineers who have used old-style inductive equalizers will immediately find a familiar sound. Younger folks who grew up with inexpensive gyrator equalizers in low-end consoles will find it a pleasant step up at a reasonable price.

Build: something old, something new

With respect to the general construction quality, Square State Solid State did some good things and some less-good things. First of all, the case is stamped from steel, which is a very important thing in the case of an inductive device because it helps to block hum from being induced by outside magnetic fields. The case is solidly built and the two PC boards are solid and well laid out; there's an external power supply, which can help a bit with hum issues and keeps costs down.

In contrast to the case, the internal carbon-element pots and rotary wafer switches look like typical consumer-grade electronics parts from the 1970s—the kind of stuff that you'd expect to find in the blister packs at Lafayette. Still, for the price point you can't complain; they operated reliably in my testing period and they don't feel bad.

Internally the unit uses inexpensive rod inductors that are designed for switching power supplies rather than a big multitap inductor. I was surprised when I saw this, because really the thing sounds better than I would expect from powdered iron rods, although the fairly wide filters may have something to do with that. Because of these inductors, though, the unit is somewhat more sensitive to stray magnetic fields than it otherwise would be.

The op-amp used in the circuit was a rather standard type, and the good news is that they socketed it so that you could try other op-amps if you were curious. In this case, though, the inductors probably affect the sound more than the op-amp, and I expect they selected the op-amp to make sure this was the case. I didn't hear any slew limiting when I used exaggerated equalization settings, like you would expect to hear if the op-amp was running out of steam.

The bypass button is not a true bypass; if you press it with the power disconnected, no audio passes through the device. (That is, the bypass button disconnects the filter networks from the feedback path of the op-amp without bypassing the op-amp itself.) This is not a huge concern since the unit is still very neutral-sounding in bypass mode, but it's something to watch out for.

Even with its steel case, you'll want to be careful about hum pickup with this eq. Don't put it right on top of a power amplifier. If you notice 60 Hz hum, move it around in your rack and try and allow a little rack space between it and the sources of the magnetic fields. For example, the power transformer on my HHB CD-R unit is on the lefthand side of the case inside the box, the same side as the Square State eq's inductors, so the HHB needs to be kept away from the Square State by a couple of rack spaces. On the other hand, the power transformer on my Great River preamp is on the righthand side of the case, and there's no problem racking it next to the Square State eq. The manual doesn't warn you about this, but it's something you will encounter with just about any inductive equalizer to some extent.

Sound: (almost) like an old friend

Normally with a review unit, I spend a lot of time listening before I pop open the case and look inside, but with this equalizer I had a good idea of what was inside the box as soon as I started turning the knobs. This is basically the same design that I used in the DIY Equalizer article in this very magazine back in December 2003. I learned about the design from the great Bel Losmandy of Opamp Labs. I don't know where he learned about it, but it's in the Audio Cyclopedia, that versatile collection of audio theory, philosophy, and circuits published in 1969.

So.... when you turn it on, what you get is the same kind of eq that you got from a high-end mixing console in 1970 or so—boost and cut equalization, with fairly wide filters. Not a huge amount of aggressive boosting and cutting, but enough for most tone shaping. The center frequencies of the filters are adjustable with a few different settings: four peak and two shelving frequencies on the low end, six peaks in the midrange, and then three peak frequencies and two shelf frequencies on the low end.

Most of the time when I use the low- and high-end eq, I tend to be using shelves and not peaks. This device doesn't have a separate switch to flip between a shelf and a peak and keep the same frequency, but instead you have to move the rotary frequency switch from one position across several others to get to the equivalent frequency. This makes it a little more difficult to compare a peak and a shelf at the same frequency—a small weirdness.

The sound? It's just like I'm used to from a really nice console eq: very neutral when you want it to be neutral, reasonable control when you want broad sweeping tonal changes. You can't do surgical eq with the thing, but that's not what it's for. You can make a bass guitar a little heavier, you can make a trumpet a little less blatty... you can do the kind of basic musical things you would otherwise use a console eq for, and you don't find yourself noticing that things start sounding grainy or harsh when you are using a lot of eq (as they do on a lot of inexpensive consoles today).

All in all

To me, this eq looks and feels like the kind of thing that, thirty years ago, you would expect the maintenance tech at a major studio to piece together from spare parts in order to meet a need not met by the studio's main board. It sounds like that, too, and that's a good thing. It's not built like a tank, it's not very elaborate, but it does one thing and it does a good job of it. The world needs more products like that.

Don't expect it to be useful for surgical eq. Don't expect it to last like a $5000 equalizer with Penny and Giles pots. But if you're looking for a simple but useful tone-shaping equalizer with a neutral but classic sound, this eq would go very nicely with a transformer-input mic preamp to make a good channel strip for tracking into a DAW. If you're working on an inexpensive console that has crude but bypassable eq, adding one of these equalizers into an insert may well give you a much more pleasant working experience.

Over all, at $499 the EQUALIZER model one b is about the only thing out there that does anything like this at this price unless you want to build your own. Good for Square State Solid State, for seeing that folks need boxes like this and for delivering them at a reasonable cost.

One final thought occurred to me as I was completing this review, that I felt I should share. Remember I said this looks and feels like something built in a studio thirty years ago? Well, if it had been, this box would be selling on Ebay for $1000 right now, if you could find one.

Price: $499

More from: Square State Solid State,; dist. by ZenPro Audio,


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