Wednesday, April 26, 2017


by Mark King for


The EQP-WA is an equalizer based on a 1960's design by Pultec Audio. The original units are some of the holiest of grail in professional recording studios and fetch astronomical prices. For years mere mortals like me could who could not afford to drop 4000-7000 dollars on a single vintage piece (provided you could even locate one) were doomed to not know the magic of the Pultec EQ.

Warm Audio changed all that with their EQP-WA. It's a two rack space, signal-processor based on the original Pultec schematics. Rather than focus on making a product that looks identical to the original Pultec's, the brilliant minds at Warm Audio came up with a design that functions like the originals but uses modern manufacturing methods to deliver the product at an almost unbelievable price of $699. The circuit at the heart of this equalizer is based on a a seriously old Western Electric design. Warm Audio has utilized mass production to reduce the street price of these wonderful equalizer circuits.

I was an early adopter and acquired a pair of EQP-WA to use for tracking in our recording studio. The allure of a piece that has been unobtainable throughout my career was irresistible. What was it about the original that made it so magical? Buying a cheap clone is not the way to absolutely know what the original did, but spending $10,000 or more on a pair of 50+ year old tube equalizers was never ever an option here.

I'm not a fan of modern clones either, the current company that owns the rights to the Pultec name has focused on high cost metal work to achieve the look and feel of the original units. I'm sure they're also very good sounding but at $3800+ each I'm not their target market. When I hit the lotto I'll bulk up on the true brand name units.


The EQP-WA sounds great. It can achieve massive bass and luscious sounding treble frequency enhancement. This is not a surgical EQ, it is much more about broad and good sounding strokes.

The controls are so non-standard for an equalizer it's difficult at first to know what the heck you're doing. After some experimenting you'll know what it's doing when you switch it out and all the mojo goes away. The rotary knob controls utilize detented potentiometers so settings are repeatable. 

This is basically a two-band equalizer with a broad bass range and an equally broad treble range. With the EQP-WA you can boost the low frequencies like no other EQ can do, it must be experienced to be understood. The bass comes up in an organic hugeness that does not get tubby nor does it lose punch or tightness. The kick drum still kicks with all its punch, the bass guitar is made massive without walking on everything. 

I've worked hard on getting the Mastering Loop on our Neve to be absolutely balanced in volume so you're hearing the effect of the process with zero volume change when the loop is switched in or out. 

The high frequency controls on the EQP-WA affect the upper octaves. The controls can be adjusted to flatter the highs like no other EQ or processor I've ever used, that's over 50 years fiddling about with this stuff. There is lots of talk about controls that can add "air" to the sound, well this is sure one of them, if you want it to. It's easy to use too much high frequency boost, that's a sign of how friendly the overall tone of the EQ is. 

The tube circuitry in the EQP-WA is so forgiving, you can push some massive boosts into your audio and never hear this EQ get crunchy or distorted, it just goes on and on with headroom that never seems to run out.

The In-Out switch simply removes the EQ part of the EQP-WA, it leaves the tube make-up gain and the input and output transformers in the circuit providing an additional color option. Speaking of transformers, Warm Audio once again looked to Cinemag in California for the iron that makes this EQ sound so good. Cinemag also provides the custom wound inductor which is at the heart of this processor. Inductors, capacitors and tubes create entirely different timbres than those created by solid state resonant circuits. 

Sweetness is the word that comes to mind in describing what this equalizer achieves. Audio passing through it becomes sweeter and takes on some additional girth even when the controls are not set for boost.

In our studio we have a Neve 8816/8804 combo that controls everything. This mixer has a switchable pre-fader processing loop which is great for final mastering effects to be inserted in before the sound exits the stereo master outputs. Once we tried the pair of EQP-WA in the stereo mastering loop they never left there again. These are the ultimate master tone controls. The broad curves and sweet tones embellish anything passing through them. This is the reason the original units became so highly coveted, they have a character that no other EQ achieves.

One problem with the EQP-WA is that the signal level passing through the unit gets boosted. As I said earlier, we were an early adopter of these units. Units from later production runs contain a trim pot on the back for adjusting the overall gain through the unit. The pair we have on our mastering loop does not have these gain controls. I made up for this by building a precision stereo mastering attenuator which is placed right after the outputs of the EQP-WA and right before the inputs of our stereo mastering bus compressor. I actually like my stereo master attenuator better than using the trim pots on the back of the unit. You can read about how to build your own here.

Another problem for us was that we bought these for tracking use, but once we heard them in the mastering loop we could not take them out for tracking. What's a studio to do? We bought another pair. We now have four of the EQP-WA, two for mastering and two for tracking.

For vocal tracking I like to use an API 312 mic preamp, then into the EQP-WA, then into an 1176 compressor and into the DAW. In this scenario I use very small amounts of EQ, just a slight enhancement in the highs and a little more heft in the lows depending on the microphone I'm using. If you use to much it will be compounded by the EQP-WA in the mastering chain.


The EQP-WA is a hit. You may not need a $1400 vacuum tube stereo equalizer but I sure did. I love these boxes. They may or may not be exactly the same as the originals, I don't care, these sound wonderful and do things I could never achieve any other way.

If they were lost or stolen would I buy them again? Absolutely, these are such good sounding boxes, they really border on magic in my opinion. The first pair of these were my first encounter with Warm Audio products, that led to a second pair and also a pair of their 1176 style compressors. It's easy to see and hear why Warm Audio has grown to be such a household word in pro audio circles, the Warm Audio products deliver truly excellent audio performance for unheard of prices. That's another win-win in my book.

Good music to all!