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| L. Stereo Pair AudioScape EQP, R. Klark Teknik and Warm Audio EQP |
For the physical size measurements I used a tape measure to check the depth of the metal enclosure from front to back, not including the knobs on the front or connectors inserted in the jacks on the rear (all of which increase the dimension from what is shown here). For context, the current Pulse Techniques, Pultec EQP-1A is 7.75" in depth (this is from data sheet, I don't have one here to measure). The three tubes used in Pulse Techniques EQP-1A model are all on the rear of the enclosure so there is no heat build up inside the box. Rear mounted tubes also allows quick tube-swaps without disconnecting, unmounting and opening the enclosure. None of the three clones in this review offer this vintage (rear mounted tubes) feature.
- AudioScape EQP-A: 3U rackmount, 19" wide, approximately 9" deep. Weight around 15 lbs. Uses their standardized house chassis shared across many of their products (same enclosure used on my Opto and Sta-Level clones by AudioScape). Tubes are fully enclosed inside with minimal venting.
- Klark Teknik EQP-KT: 2U rackmount, 19" wide x 5" deep). Weight 6.6 lbs (3.0 kg). Tubes fully enclosed with NO air vents.
- Warm Audio EQP-WA: 2U rackmount, 19" wide x 3.5" high x 6" deep. Weight approximately 10 lbs (4.5 kg). Tubes fully enclosed with NO air vents.
Construction notes: AudioScape chose to keep the front panel and enclosure at a full 3 rack spaces using their standardized box design. This has nothing to do with vintage Pultec construction — the original EQP-1A was more compact in depth and put the tubes out back on the rear for easier servicing in the rack.
With all these clones, the enclosure is purely a builder’s choice for standardizing production and controling cost. In the case of Audioscape their design choices make the units significantly larger and take more rack space area than Warm Audio or Klark Teknik (significantly more than a real Pultec). A friend who had never seen an AudioScape unit in person saw one of mine and immediately said "what a beast". I can only guess that using basically the same enclosure for multiple products helps keep cost down.
The AudioScape uses through-hole components on good-quality PCBs with minimal point-to-point wiring. It is not vintage-style turret board or old-world hand-wired construction. To get inside to where the tubes are you go in through a removable top cover (you'll need a screw driver too).
The KT uses two high-quality circuit boards and has zero air cooling vents for the two vacuum tubes inside the box. All sub-assemblies (including the external output transformer) and PCB interconnections use locking connectors, which is nice for future servicing if required. Tube replacement is still not fun though — the tubes are tucked away and a bit difficult to extract. The pots on the KT appear to be sealed types, consistent with other recent Klark Teknik products. The metal top of the enclosure is where you go in to replace tubes but you'll need a star-driver tool to remove the screws.
The Warm Audio EQP also requires removing the enclosure steel lid to replace or exchange the vacuum tubes from its unvented enclosure.
The KT and the Warm Audio EQP both use solid-state rectifiers while AudioScape chose to use the original tube rectifier design. Without methodical and careful A-B listening test demonstrations it is difficult to point at the use of the tube rectifier as a game changer sonically. These are not guitar amps and I'm feeling that passing big audio signals in and out of an EQP does not actually sag the power supply and cause compression (one of the most commonly attributed sonic characteristics associated with tube rectification).
For reference, tube rectifiers been a big part of my life, when I serviced B&W TVs in the 1960s.
TUBE COMPLEMENT
- AudioScape: Claims “full NOS” 12AX7, 12AU7, and 6X4 rectifier tube. They don’t specify which actual vintage tubes are used (different brands and vintages sound quite different).
- Klark Teknik EQP-KT: One 12AX7 + one 12AU7 — Bugera Premium Select tubes (sourced in China). We don’t know the exact sorting or selection criteria, but initial function testing showed them to be low in residual noise (quiet) with good full-range response and no obvious microphonic flaws (tested by gently tapping with a wooden pencil).
- Warm Audio: One 12AX7 + one 12AU7 (premium selected - no specific information given about what “premium selected” means or who does the selecting).
The 6X4 rectifier in the AudioScape is marketed as a key authenticity point. In reality and functionally the difference is subtle in these low-current circuits. The rectifier's job is to change AC into DC and feed a bank of hungry capacitors which smooth and filter out residual hum/noise and deliver power from a solid pool of clean DC-power. I appreciate that AudioScape is trying to stay authentic to the original schematics.
WHO IS PULSE TECHNIQUES
WHAT TUBES DOES PULSE TECHNIQUES CURRENTLY USE?
If you spend $4500 on one new EQP with the Pultec brand name on it, what tubes come in it? I'm unable to find anything definitive and the company does not disclose publicly in marketing what they use. Anecdotal information points to Electro Harmonix branded tubes from Russia.
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| Midas Transformers in KT-EQP |
TRANSFORMERS
- AudioScape: Custom-wound input and interstage transformers (HS-56 / HS-29 style) + Carnhill output transformer (a modern recreation of the rare Peerless S-217D). The AudioScape is the only one to include the interstage transformer.
- Klark Teknik: Custom Midas-designed input and output transformers. In my experience so far these are not just “budget” iron — they perform very well professionally and deliver a solid +21 dBu input and output level handling that the other two units don’t publish or discuss.
- Warm Audio: High-quality USA-made CineMag transformers (input, output, and inductor).
All three of these EQP equalizers feature transformer-balanced inputs and outputs. The AudioScape uses the rare Peerless output transformer design, which is only rare because nothing else uses these; in addition not very many were made because the EQP was expensive and specialized. While it is rare it is not magic, it IS interleaved windings with 50% nickel used in the laminations. An extra winding provides negative feedback for distortion reduction.
ABOUT THAT INTERSTAGE TRANSFORMER
If you read forums you're already aware that the Warm Audio and Klark Teknik EQP don't have the "interstage" audio transformer which connects the EQ section to the output driver section inside the vintage original design. Interestingly, the most ‘authentic’ unit in the group (AudioScape, which retains the interstage transformer) didn’t come across as the warmest or most colored. Instead it sounded like the most subtle and integrated — almost like a gentle tone control rather than an obvious equalizer. The simplified designs in the Warm and KT actually felt more forward and easier to hear the effect on aggressive settings.
CONTROLS - FREQUENCIES - WARRANTY
All three follow the classic Pultec layout and allow the famous “boost and cut at the same frequency” trick on the lows.
- Frequency selections are very similar across the board (expanded from the original).
- Boost/Cut ranges: Comparable across the models.
- Pots: AudioScape lists “Alpha Potentiometers.” To an old DIY guy like me this feels like disingenuous marketing hype portraying this brand as “boutique or even high quality”. These are standard, inexpensive carbon-track pots — the same garden-variety parts I’ve been buying from Mouser since the early 1990s. They are not sealed, don’t have tight tolerances, and aren’t known for exceptional longevity in terms of rotation cycles. Marketing them like they're high end components alongside premium transformers and NOS tubes dilutes the credibility of all the component hype.
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| Click to enlarge |
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| Click to enlarge |
BYPASS ISSUES
All three of these EQ units share a common problem (or virtue depending on marketing) - the bypass switch does not actually bypass ALL the internal circuitry. This is portrayed as an original feature which gives you the tube and transformer tone characteristics without the EQ boost/cut when bypassed position. It is just my opinion as an engineer who has struggled with gear dying in sessions for well over 50+ years, BUT, I'd like any of these better if they had an actual BYPASS IN/OUT switch which takes it completely out of the signal path for trouble shooting and sonic evaluation along with an EQ-IN/OUT switch like they currently have. With a hardwire bypass you flip the switch when a gadget dies and carry on with your session with all circuits out of the loop. With the stock setup these EQP pieces offer, you're going to need to do some wiring changes or swap units to get it completely out of your signal path.
Back in the 1950s when this EQ was first designed, everything was vacuum tube and transformer driven (very high impedance circuits). Today our studios are filled with solid-state gadgets (very low impedance circuits). When we mix old tube designs with modern solid-state gear we end up with level and frequency response shifts (you do know about terminating resistors don't you?).
A second TOTAL BYPASS switch could have been added that would shine a light on the serious level shift that happens when you pass a signal through any of these EQP brands. I use a precision Coleman TC-4 as part of my recording and testing, this allows an effect like EQ to be completely bypassed revealing a true A-to-B switch, WITH and WITHOUT which really helped me focus on these level and tone shift characteristics.
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| Level Trim on Warm Audio EQP |
Warranty & Street Price (approx. USD, 2026)
- AudioScape EQP-A: 2 years, $1,200–$1,500+ per mono unit. Sold primarily factory-direct from audio-scape.com.
- Klark Teknik EQP-KT: Typically 3 years, $285–$320. (I got a killer deal on one during a big sale, and it sounded so good stock that I decided to add the second one and include both in this comparison.)
- Warm Audio EQP-WA: 5 years (with registration), $750–$850.
AudioScape attempts to portray a lower-priced but high-end, authentic vintage experience through their marketing and meticulous front panel recreation (which looks like the original when it's in a rack). Out of ten AudioScape pieces I’ve purchased in the last three years, one arrived visibly and sonically malfunctioning (a 6V6 power tube lighting up like a light bulb). Their support was quick to send a complete replacement set of tubes which fixed the issue, but better QC should have caught it (they have since switched to Electro-Harmonix 6V6 power tubes on the V-Comp).
AudioScape has been using a large standardized chassis, modern PCBs, and standard off-the-shelf Alpha carbon-track pots. Looking inside it feels like a garden variety Mouser parts list with thru-hole (vintage?) resisters inside a standard production box rather than a true through-and-through boutique recreation. I very much appreciate their focus on “Sonic Truth” (providing gear that sounds good). In the testing/comparisons we'll shed more light on their marketing claims.
The Klark Teknik EQP-KT is the compact, low-priced, lightweight option with the best published specs and headroom. This is the low cost player in this roundup, manufactured in China using one of the world’s largest installations of Audio Precision integrated manufacturing and testing. The Midas-designed transformers punch well above their price point, the build quality is thoughtful for servicing, and the stock Bugera tubes were surprisingly clean sounding and low noise right out of the box. The enclosure is their own compact design and it is all steel which provides the best performance for rejecting hum and noise from the outside world.
The EQP-KT is on sale sometimes at even lower prices than their normal retail selling price (currently $285 each). I bought one six months ago on one of these sales and I’ve been inserting it on individual tracks when mixing (my AudioScape EQP pair usually sit on the mix bus through the Coleman TC-4).
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| UPPER: KT HF Cut, LOWER: WA HF Cut |
The Warm Audio EQP sits between the other two in this review price wise. This was one of the first lower priced clone-EQP options to hit the market and it delivers strong low-end heft thanks to those CineMag USA transformers. Sporting a reasonable price and now backed with a solid 5-year warranty this EQP is worth a look and a try. Bryce at Warm Audio is a fanatic about components and parts for obtaining good performance and sound. His company has really stepped up their game in the area of quality control.
I like that Warm Audio uses great circuit boards and quality through-hole components (instead of all surface mount like SSL and KT). Warm Audio uses off shore labor for construction to keep costs low (same as SSL) but includes American made transformers and most importantly, they maintain a staff in the USA who checks out every piece they ship.
I like that the Warm Audio EQP and the KT version both provide XLR and TRS connections on the back. I personally use TRS as much as I can for balanced wiring standardization in our studio but I know there are lots of folks who favor XLR for their “locking” connection. There are a number of Warm Audio products in our studio and we mix them in with our Neve, vintage AKG, API, Grace Design, Locomotive Audio, UA and other expensive processing without problems.
Warm Audio has also built a world class recording studio complete with dual control rooms, each outfitted with a $100K SSL automated mixing console and premium monitoring. This provides the company with a truly high-end sonic testing environment for developing their products. Industry giants like Sylvia Massey and Eddie Kramer have hosted seminars at Warm Studios so they're doing something right down there in Texas.
DEALERS VS FACTORY DIRECT
AudioScape builds to order and sells direct to you from their factory in Daytona, Florida. Build-to-order lead time varies depending on the product. Currently their web site shows EQP-A on sale and available for immediate shipment. The "Mastering" version of this unit requires 4-5 weeks of build time. When I got a bum unit from them AudioScape was fast to get me replacement tubes but I had to unmount the piece, open it, swap the tubes, reinstall in the rack and reconnect. In addition there was still a matter of testing time to see if it would be reliable. If I'd bought from Sweetwater I would have already received an advance replacement unit and they would have been the ones replacing the tubes and checking out the defective piece of gear when I returned it with them paying the shipping. I know this because they've taken care of me at least six times in the last 10 years.
Klark Teknik and Warm Audio sell through dealers, this means they build A LOT of units, ship them to dealers all over the world who then offer them to you. Dealers typically get AT LEAST 20% to 30% of the sale price for their efforts (referred to as dealer markup). Dealers deserve a slice for taking care of warranty servicing and taking care of the customer (so you can focus on making music instead of repairing gear). If you've ever tried to deal with KT or their parent company, Music Tribe, then you can really appreciate a dealer (like Sweetwater) who goes to bat for their customers.
In this day of shopping on the internet having a dealer on your side is VERY IMPORTANT because one of these days you're going to get a dud gadget. Price matters but service matters too. The cheapest price might be all you can afford but when your new darling dies where's the savings? Service matters A LOT!
SOUND TESTING
Some sonic characteristics surface rapidly when you begin using these EQP recreations side by side on the same material. (I use a variety of sounds for sonic testing which include: premium vintage Zildjian cymbals for high frequencies, acoustic guitar for character, and direct slapping funk bass for low end, as well as full mixes for overall character). Here are some overall impressions from using all three of these extensively here in the High on Technology studio.
I could use any of these three EQP clone units in music production depending on what I'm attempting to accomplish. Each has strong and unique characteristics which make them desirable. The Warm Audio model has the biggest, boldest bass boost, the Klark Teknik offering has the most Hi-Fi characteristics (clean and precise) while the AudioScape excels as a bus processing program equalizer - it stays out of the way and provides gentle, predictable sonic shaping.
AudioScape: EQP-A
This is the only one I would consider on my mix bus. It has a soft impact on the sound, it never feels clinical or precise. There is a gentleness that is difficult to describe when you're zeroing in on frequencies with the controls. I rely on quick A-B comparing with the Coleman TC-4 switcher to hear exactly what's going on. While these sound excellent as bus sound shaping tools I found them less useful patched on specific tracks when mixing. That same gentle impreciseness that allows master bus tracks to be modified carefully lacked power and precision on individual tracks. The beastly physical size of these means they need to be immobile in a rack somewhere. By the time you have XLR cables sticking out the rear these EQ are physically BIG.
Klark Teknik: KT-EQP
Patching one of these in delivers a unique and different listening experience from the other contenders. Many forum posts portray this unit as lame or distorting tone by just hooking it up, I never felt like it did any of that. The KT has a tight HiFi sound, it is crisper and more defined than the others. I really grew to like this piece inserted on individual vocal tracks when mixing. When you dial up boost in higher frequencies it is easy to hear the effect (also easy to add too much). The 20K HF Cut really has a nice vintage effect on tracks that sound too bright or leap out of a mix in an awkward way.
I'm not a fan of solid state distortion effects on guitar recorded direct but having the KT-EQP gives me a quick easy to access tool to shape that nasty rasp from a RAT or TubeScreamer into a tone that sits with other instruments in a much more pleasant way. The compact and lightweight form factor of the KT-EQP makes these easy to rack-up and stack up in compact portable racks so you can move them around the studio and use them where you need them. The KT-EQP are mass produced but the soldering inside, the components and the build quality are on par with much more expensive products like those from SSL.
Warm Audio: EQP-WA
I have literally had customers bring their mixes to me to add the bass sound of the EQP-WA. I don't make a big deal about how I do it. They get their track to me, I bounce it through the EQP-WA and record it at 192K in stereo and return the much larger file to them. They can reduce file size or upload it directly to SoundCloud. This high sample rate recorded on my Tascam DA-3000SD two-track recorder sounds super smooth and it delivers the Warm Audio EQP bass response like nothing else. This is the closest I can get to the character most people fantasize about when they think "tape".
The Warm Audio EQP is the least HiFi sounding of these three units, it's got character (and that's a good thing). This EQP makes its presence known with a great midrange-ringing inductor vibe which sounds best patched directly on a track when mixing. It's a sound quality I associate with old custom built British studio gear. This EQP excels at adding weight (huge bass), 3K smack or soaring high frequency sting.
LISTENING WRAP-UP
All three of these EQP clones sound unique and different from each other. I've found uses for each of them in production. There is not one that distinguishes itself in all applications. The Warm Audio and the Klark Teknik models have the most punch and raw power. The AudioScape sounds the smoothest but lacks the "sting" ability of the other two, very handy on a dull sounding recording of a Fender amp. All three of these EQP are TONE-CONTROLS and you use them for shaping the sound so it all congeals and sounds well integrated (many people call this "glued").
EPILOGUE
Beyond ALL the hype and marketing you pile on any of your favorite gear items, by far, the thing that matters most is whether you use these products to make music and be creative. I read forums and I’m aware of what others say about all these brands but I choose to make my own decisions based on hands-on testing, listening and actually mixing (not just posting about it). It seems like a lot of folks like to treat gear like sacraments in a religion - to me they're nothing but tools.
I only had one chance in the last 60 years to evaluate a real honest-to-goodness vintage Pultec-brand EQP - that was back around 2004 - my feeling at the time was that it severely rolled off the high frequency of the test track. It was SET right, it was just an old tired piece of gear and was clearly not functioning up to snuff (typical of a lot of used vintage gear).
These reproductions are all lower priced than the product that currently wears the official Pultec brand badge (also a reproduction since the original manufacturer closed up shop many years ago - 1981ish). I look at all these gadgets as tools to help me make the best music I can and we’ve put the music all out there on Mark King Radio where you can listen to it.
I urge you (as much as possible) to use your own ears, learn how to make your own decisions based on what you hear. I don’t spend very much time listening to YouTube or internet demos because honestly, it is just too easy to “fake” online results. The data-compression characteristics of YouTube are much worse and detrimental to accuracy than most people acknowledge.
No matter what you buy, one of the most important things your dealer/source can offer is the ability to return the product if you don’t like the way it sounds. No demo can match the results you will hear when you actually put your hands on and use a piece of gear in your own personal studio.
Thanks for reading High on Technology, Good Music To You!
©June 2026 by Mark King, it is NOT ok to copy or quote without written permission from the author.
PULTEC-STYLE EQP TRICKS - low frequency boost and cut on same frequency
On a Pultec, something weird and cool happens when you do both at the same time on the same frequency (for example, boost 100 Hz and cut 100 Hz).
What Actually HappensThe boost is wide (it affects a broad range of bass frequencies), while the cut is narrower. So instead of canceling out, you get this weird shape:
- You add a big, round, thick low-end boost.
- At the same time, you carve out a little dip right where it was getting too muddy or boomy.
- You add more ice cream → it gets thicker and richer (this is the boost).
- But then you suck out a little bit of the extra milk that's making it too watery and gross (this is the cut).
What It Does to SoundWhen you do this on a Pultec:
- The low end gets bigger and fatter (more weight and body).
- At the same time, it gets tighter and cleaner (less mud and boominess).
Originally published June 21 2026
