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Square State Solid State EQ One B
Single Channel Equalizer, Inductor Based 3 Band w/ Bell or Shelf
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Fake Price................................... $599.00
Real Price............... $499.00
2 or more$475.00
Power Supply 115v / 230v
Status: Usually Ships Same or Next Business Day

SquareState Solid State EQ Model One B Description

Read Scott Dorsey's Recording Magazine Review: CLICK HERE

Read TapeOp reviewer Joel Hamilton's initial thoughts: CLICK HERE

Introductory Offer: $950 Pairs (add 2 to cart and save)

It kind of looks like an old Urei offers similar but more points than a has an electric "tingle" to the sound, reminiscent of old Electrodyne or Pultec style EQ's...the bell bands are wide enough for 2 buss use...and it's made in the USA for $499. Well kick me in the head...

Square State Solid State model one b is a single channel, three band equalizer housed in a 1 RU chassis. The equalizer stages are comprised of inductor-capacitor filters, components commonly found in classic EQs. The EQ offers 6 frequency selections per band, each offering roughly 20 dB of cut/boost. The bell-shaped (bandpass) response curves are broader than similar equalizers, lending themselves to a very musical sound. Additionally, the high and low frequency bands offer both shelving and bell responses.

The model one b is a swinging input equalizer. This is an equalizer circuit topology that is based on inductor-capacitor-resistor (LCR) filter networks. These filter networks are crossfaded between the inverting and noninverting inputs of an operational amplifier, resulting in adjustable cut/boost for each band. While the LCR filters are passive, the opamp provides makeup gain and buffering, such that the overall circuit is active.

While the underlying circuit is old, the design for the model one b is new, and provides more versatility than common vintage swinging input implementations.

Square State Solid State EQ Model One B Specifications

  • Physical:
    Size: standard 1 unit rack enclosure: 19" wide, 1.75" tall, 6.375" deep overall (5.375" behind mounting rails).
    Weight: Approx 5 pounds.
  • Connectors: Audio on standard balanced 1/4" TRS connectors.
  • Electronically Balanced Input: 10K Ohm input impedance, each leg to ground.
  • Impedance balanced output: 47 Ohm Output impedance.
  • Power: 2.1 mm barrel connector for 15 VAC transformer.
  • Controls:
    Bypass switch with LED
  • Low Frequency Band:
    Filter selector switch offering 75 Hz and 150 Hz low shelving filters
    50 Hz, 80 Hz, 100 Hz and 150 Hz bell filters
    Continuously variable cut/boost control, approximately +/- 20 dB range.
  • Mid Frequency Band:
    Filter selector switch offering 220 Hz, 350 Hz, 700 Hz, 1.5 KHz, 3 KHz and 6 KHz bells
    Continuously variable cut/boost control, approximately +/- 20 dB range.
  • High Frequency Band:
    Filter selector switch offering 7 KHz, 12 KHz and 17 KHz bells
    7 KHz, 12 KHz and 17 KHz high shelving filters
    Continuously variable cut/boost control, approximately +/- 20 dB range.

Visit Square State Solid State's Website:


Bypass (44.1/24) EQ One B (44.1/24)
 Bypass (mp3)
EQ One B (mp3)
 TOM 1
 TOM 1
 TOM 2
 TOM 2
 TOM 3
 TOM 3



You can right click and "save as", then load these files into your DAW and listen in your control room.

Files are pre-recorded with no EQ, and offered here in 44.1/24 bit wav and 320k (highest) mp3 in bypass and equalized form. All cabling is Mogami, conversion done via SSL Alpha Link MADI AX / Rain Recording Element PC / Nuendo 4, monitored on ADAM P33A / Manley ML10A, mp3 processed in WaveLab 6.

Source & EQ Settings:

  • Kick: Boost 50, cut 350, boost 7k bell 
  • Snare: Cut 75 shelf, boost 220, boost 12k bell 
  • Overheads: cut 150, boost 17k shelf 
  • Tom 1: 150 boost, 350 cut, 7k boost bell 
  • Tom 2: 80 boost, 350 cut, 7k boost bell 
  • Tom 3: 50 boost, 220 cut, 7k boost bell
  • Bass: 80hZ boost, 350hZ boost, 7kHz bell boost
  • Male Vocal: 150hZ cut, 3kHz cut, 7kHz shelf boost
  • Female Vocal: 75hZ cut, 220hZ cut, 7kHz shelf boost
  • Ac Gtr: 75hZ shelf cut, 220 boost, 12kHz shelf boost
  • Cello: 50hZ boost, 6kHz boost, 17kHz shelf boost
  • Mix Buss: 80hZ boost, 350hZ cut, 12kHz shelf boost

Quick Test Notes:

  • Kick, Snare and OH work together as a group lined up at zero in your DAW
  • Toms 1, 2 and 3 work together
  • Female Voc, Ac Gtr and Cello performed by i-nine and work together as a song piece
  • Stereo Buss features Damn. The Sun
  • Drums, Bass and Vocals by The Thirsties

Square State Solid State EQ Model One B Review / See All ZenPro Audio Reviews Here: Review Page

When Joe Turse approached me saying that he and partner Byron Jacquot were about to crank up production on a USA made inductor based EQ that would nail a sweet spot of performance and price, well you know me that’s what I love! I was excited by the prospect, but the best part is being more excited once I actually got to use a final production model on all kinds of sources and hear the great character it imparts while still remaining detailed, coherent and musical. Passive inductor EQ sound meets active low noise operation that retains detail while imparting that “electric” vibe.


On the rear the Model One B features TRS in and out on and a “wall wart” AC adapter jack. The unit is transformerless in and out and utilizes a very high quality op-amp for clean gain staging and full balanced operation. There are 3 bands of equalization available and if you look at the available points you realize how friggin’ easy of a reach the EQ1B is. There is roughly +/- 20dB of cut or boost available per band (a lot).


I get very excited by EQ’s that are functional in a not too tweaky way. Having the right points to reach for on a majority of sources absolutely rules in my book. I work fast when recording and like to dial things in quickly. I also realize that tracking a record is like building a puzzle and that EQ really is the most essential reach for pop and rock recordings and that it should be committed to during the tracking process as often as possible. Why? Everything needs its own space and equalization is the way to balance and fit things, period. Mic selection is key, but EQ will mean more than any preamp selection etc beyond that. In a dense mix EQ is absolutely essential to keep things from crowding in the wrong way. Also, any fan of pushing the faders up and hearing a coherent mix instantly knows that EQ along the way got you there.


The tone of the Model One B lives in a unique place that is familiar. Unique in that it is extremely low noise and high detail thanks to the simple but top notch op-amps used for gain, but is giving you that classic passive inductor EQ sound that is so harmonically sweet and “tingly” (ala Electrodyne / MCI style designs) and delivers punch and authority.There is a life to the sound that I absolutely dig, vibrant might be a good word here.


Being able to roll off heavy at 75hZ or 150hZ on the bottom is nice on things like electric guitars and other things that collide with bass. An anemic kick drum or bass guitar will benefit also by boosting here and bringing up lower frequencies along with it. However, the four bell points available on the low end are well chosen for tweaking and if you need to boost say 50hZ on a kick drum you won’t bring up as much crazy sub stuff down below. The mid band has lots of great problem solvers, from being able to cut 220hZ from vocals, gut a kick drum or tom-tom at 350hZ, boost 700hZ to bring back the “bap” of a bass guitar, taking the pointy sting off a snare drum at 1.5kHz, pulling a bit of sibilant vocal back at 3kHz or bringing back some presence at 6kHz, well you get the point. They are a great collection of frequencies to reach for! The top end brings that more tingle-y “electric” vibe common to inductor designs, 7kHz to bring snap to drums or presence to vocals, 12kHz for cymbal and acoustic instrument brightness, and 17kHz for “air” (I find a subtle amount to be excellent to hear room detail). You need to remember that with +/- 20dB of gain per band this means that 1/3 up or down on the pot can be more than enough (many EQ offer about 12dB of control). It’s nice to be able to get extreme though if you need, like bringing the top end back on using a dark ribbon mic on drum room.


Conclusion: I think when you marry the most desirable EQ sounds with modern high detail low noise for digital recordings, you end up with a great EQ. The fact that these points just work on virtually every pop and rock recording source instantly and subtly enhance the tone without killing detail just makes them clear winners. This is not a clone but rather a unique use of classic technology and new. Kudos for not bringing another "clone" but something we all can relate to.


(3 Ratings, 3 Reviews) Average Rating:
Great price for an awesome unit!
Steven R (Calgary, AB) 11/21/2011 9:39 AM
For the price this thing is just awesome. I've gotten great results are almost every source I've tried it on. My other EQs are all plugs (UAD stuff) and although I do like some of them ever since I got the 1B it probably gets used 80% of the time. Extremely satisfied customer here.
Anthony Guyer (Lancaster, PA) 8/28/2011 10:48 PM
I love my EQ1b. It has enhanced everything I have used it on. I am not one to try to get one thing to sound like something else so I couldn't tell you if it sounds like ... But I like to turn some knobs and get a cool usable sound right away. This unit has done it marvelously for me. I am anxious to pick up a second and play with it on the 2buss.
Happy with the One B!
Brian McRae (Lyons, CO) 12/28/2009 6:47 PM
I was curious about these units after Joe Turse told me about his new company. I have always respected Joe's love for electronics and creating art. Well he delivered once again with the Square Solid State EQ Model One B. I bought 2 units sight unseen and have been very happy with them on Overheads. I look forward to using them on most everything. Thanks Joe! Brian McRae