Classic Audio Products Inc. VP-26

How I Learned to Stop Worrying and Love Saturation


I remember the first time I used the output knob on a microphone preamp.  I was interning at a recording studio built into a old farmhouse right next to the historic Antietam battlefield.  Although I try to make recordings that transcend place, I am also a firm believer in the power of location to shape performances and inform creative decisions.  Watching the fog nestle itself among the blades of grass in the morning helped me clear my head and prepare myself for the day.  Sometimes it felt like I worked in a place untouched by humanity, as ironic as that statement might seem.


A freshly minted CAPI VP-26.

The studio owner, for whatever reason, liked to keep his preamp tones as clean as possible and kept the output knobs in the furthest clockwise position.  This was around the same time I was trying to understand what saturation was, and the myriad ways in which it could be used.  It was hard to separate the facts from the marketing hype surrounding all of the products promising that magical “warmth,” “fatness,” “glue,” and the other buzzwords that are used to describe the qualities of analog gear.  Looking at the different plugin offerings, it was hard to discern whether this saturation came from tape, tubes, transformers, or some combination -- and whether the magic could really be reproduced digitally.  All I knew was that dirtying my tracks in some way could make them sound more like a record.  How this happened exactly was a mystery to me.


One day, I was recording acoustic guitar by using a Royer 121 pointed at the bridge, and a small diaphragm condenser aimed at around the 12th fret.  The musician was playing a folk tune with lots of intricate picking.  The R121 was picking up the body and warmth of the guitar, while the small diaphragm condenser captured the detail.  I turned the gain up on my preamps until I had a good level.  Everything was there, but something unquantifiable was missing.  I couldn’t place it until I trimmed the output knobs on my preamps and drove the gain some more.  The signal thickened in an incredible, musical way, and the harmonics came to life.  There it was -- the sound of a record.  Vibe.  Character.  Mojo.  These things that I was convinced were just bullshit marketing terms suddenly became real and meaningful.  I felt like I’d stumbled onto some deeply held secret about how to properly make records.  Needless to say, this experience will forever be one of my favorite, most eye-opening moments as a recording engineer.


How Does It Sound?


The preamps I used that day were CAPI VP-25s...and yes, I know this post is supposed to be about the CAPI VP-26.   Bear with me.  Classic Audio Products, Inc. -- or CAPI, for short -- is a company that produces DIY versions of preamp, EQ, dynamics, and other modules that were included with vintage API consoles.  These consoles are commonly regarded as some of the best ever made -- up there with Neve, Trident, and SSL.  Moreover, with their punchy, mid-forward sound, they are the quintessential consoles for rock music.  Sourcing original API modules can be an expensive proposition, but luckily Jeff Steiger, the owner of CAPI, has gone to great lengths to clone these classic circuits for the 500-series format.  With detailed building instructions available online, it’s relatively simple and inexpensive to order a kit from CAPI and build one of these wonderful modules yourself.  


Back to the VP-25s I was using to record that folk guitarist: these preamps are nearly identical to the VP-26s, the only difference is that the VP-26s have a slightly smaller 2623-1 output transformer, which was used in API console preamps.  The rest of the circuit is identical.  What does this mean for the sound?  Tonally, the VP-26 is the more “vintage” sounding preamp, with the VP-25 representing a halfway point between it and the more modern VP-312, the latter of which is a clone of the legendary API 312.  Both the 25 and 312 feature the 2503 output transformer.  I have not done a head-to-head comparison with these preamps, but from what I’ve read, the VP-312 is slightly more open sounding, whereas the VP-26 is bigger and tighter in the lows and lower-mids.  For those wondering -- don’t worry, the VP-26 can produce that same euphoric saturation I got from the VP-25.


To date, I have built 5 VP-26 preamps, 4 of which reside in my home studio.  I’ve used them to record a ton of sound sources: vocals, overheads, drums, acoustic guitar, electric guitar, electric bass, and upright bass.  Considering that it is a clone of a console preamp designed for everyday use, it isn’t surprising that the VP-26 performed well in all of these applications.  It can produce a pristine sound that’ll have you opening up the module to check if you accidentally installed a John Hardy 990 opamp, or you can trim the output and drive the input gain for a killer retro tone.  I find it particularly useful on drums and acoustic guitar.  On the former, it delivers the punch and aggression that is so strongly associated with API preamps, and on the latter it produces a smooth, well rounded tone with plenty of transient detail.  As a vocal pre, the VP-26 doesn't always sound quite as upfront as I'd like, but does produce balanced, usable results.  When I first built a pair of VP-26 pres, I was upgrading from the pres in my Avid Mbox.  It's worth noting that in any application, the VP-26 is a major step up from the preamps included with most audio interfaces, which tend to be IC-based and offer a flat, colorless sound.  CAPI preamps certainly made me a believer in transformers and direct opamps, and I'm willing to bet they'd make a convert out of anyone looking for a more analog-sounding recording chain.


Build Review


As of writing this, I've built 5 VP-26 preamps, and 4 of them worked perfectly right out of the gate.  The one that didn't (my first) had a resistor in the wrong place, which, after the unit was plugged in for a few minutes, burst into a tiny flame.  Now I get why they call it the “smoke test.”  Anyway, there aren't too many parts in the VP-26, and there are build tips and a bill of materials (BOM) available directly from CAPI, as well as a build guide (with full HD photos!) from DIY aficionado Chunger.  Out of all the preamps I’ve built, the VP-26 is the least complicated.  Part of the reason for this simplicity is inherent in all 500-series modules -- no power supply is required, since the 500-series rack already provides power.  Another reason why the 26 is so easy to build is that it is a single stage preamp, as opposed to a two stage preamp.  Lastly, this is a simple, tried-and-true design that works as well today as it did in the 1970s.  Personally, when I build a VP-26, I like to print out the CAPI BOM, arrange my parts on top of it, then follow along with Chunger’s guide.  Be careful that you check the support documents on CAPI beforehand -- there are several revisions of this preamp so make sure you have the most up to date BOM.  Schematics and overlays are also available through CAPI.  

The author building a VP-26.

Although the VP-26 is relatively simple to build, if you're a true DIY novice it might be a better idea to start with something with even fewer parts.  If you've already built some preamps, it's almost guaranteed that the VP-26 will be easier by comparison.  You will probably find the hardest part of the build to be the direct opamp, of which CAPI offers several choices for slightly different tones.  There's the GAR2520 (a clone of the famous API 2520 opamp), as well as the GAR1731 (a clone of the Melcor 1731).  Or -- if you're like me and don't feel like building an opamp -- the Scott Leibers SL-2520 is available pre-assembled for an extra charge.  I haven’t tried the other op amp choices, but the SL-2520 performs perfectly and has a great tone.  In addition to having different opamp choices, you can also choose to build your preamp with variable or stepped input gain controls.  The stepped option costs more and requires you to solder a few more resistors, but it may be a worthwhile investment for those who need recallability.


If you're looking to get into the world of high quality, external preamps, and want something with serious vintage character to boot, the CAPI VP-26 is one of your best options, not to mention the most affordable.  Plus you get to work on your DIY skills while you're at it. For more information: