Silktone Guitar Amplifier
By Chris Loeffler |
Could this amp be smooth as ...?
I first spoke with Charles Henry years ago when he asked me to review his Silktone instrument cables. During my fact-check call with him to dive into the science vs. mojo of a “directional” cable (FWIW, the science behind double conductor cables and single-path shielding made me a believer it is more than marketing hype), he mentioned he had been working on an amp for a few years and would likely release it at some point in the future. As he walked through his design philosophy and approach, I left the call thinking two things; this guy REALLY cares about gear and it was unlikely the amp could be as revolutionary as he described it, given we’re talking about variations on a century-old design. Then, nearly four years later, Charles called back asking to confirm my address to send out a loaner unit for me to check out.
The Silktone guitar amplifier is a Tweed-inspired 12 watt single-ended, cathode bias guitar amplifier powered with a 12AX7, 2 12AT7, KT66 , 5AR4/GZ34 tube compliment and spring reverb tank feeding a custom-designed 12” Warehouse Designed speaker with controls for volume, tone section, and reverb.
What You Need to Know
The Silktone amplifier design started from the humble (but venerated) Tweed foundation, with a single tube in the preamp (12AX7), power (KT66), and rectifying (5AR4) sections of the amp with a philosophy that getting more from a single tube in each section creates a richer, more responsive sound. The major deviance from the tradition Tweed circuit comes in the form of replacing the traditional 6L6 power tube with a true KT66 (note many modern “KT66” tubes are 6L6s with a different bottle) for stronger bass and mids. The KT66, to my ears, sounds like a sweetened version of 6L6, with less congestions in the transition frequencies and a more layered growl.
The single ended cathode design translates to a couple of things most players will hear (and feel) immediately, most obviously a livelier tone at lower volumes. This isn’t just a “low wattage” phenomena, it is directly tied to the relentless work required of a single power tube and a more immediate response than is created in a push/pull scenario of power sharing between two tubes.
It is worth noting that although I didn’t experiment beyond 6L6, the Silktone amp can run on a 6v6, 6L6, EL34 or KT66 without rebiasing (thanks to cathode biasing) for different flavors of power amp distortion (and output wattage). The designer, however, emphasizes he’s voiced the tone stack and speakers to a KT66, and that is where he believes the amp is realizing it’s optimal tone.
To that point, there’s an excellent point of flexibility in how the amp is voiced between the Chiffon and Raw Silk modes. Chiffon is the “refined” side that incorporates a tuned Bass, Mids, and Treble control section that instantly places the amp in a highly flexible variant of the vintage Fender mid-scoop base tone. The bass stays robust and the highs have a tight brightness to how they sit. I don’t want to lean too heavily on the “Silver Face” comparison, but that’s where my ear kept going. With the mid knob at 9 and treble and bass at 2-3, the scooped thing I was most present, whereas setting the treble at 11, mid at 12 and bass at 3 yielded a nice fat jazzy sound.
While I loved the Chiffon voicing and knew Silktone had a winner based on that alone, switching to the Raw Silk mode was brought my review experience to another level. What this mode does, functionally, is entirely bypass the tone stack circuit. Sonically, it produces a primitive, fat sound that jumps from the amp. Cleans are livelier and mode vivid, and the gain (which starts happening around noon with single coils) is punchy and compresses in an incredibly dynamic way, almost flawlessly shifting points of frequency overdrive based on how hard I hit it. The Volume and Tone controls on my guitars have likely never been as vital to accessing different sounds than they were with the Silktone amplifier.
I very much preferred single-coil pickups (the newest version of the Fender Vintage Noiseless and the Bareknuckle Slows hands I demoed, in particular) due to the revealing and reactive nature of the Silktone amp. Humbuckers (especially the Classic ‘57s and Mules I demoed) do sound great, but the limited dynamic range of their output stands out starkly in Raw Silk mode.
The reverb section, something I tend to use sparingly on Fender-style amps unless I’m seeking an exaggerated surf tone, sounded different from the vintage spring tanks I’m used to. It has almost none of the hollow, hazy character of a vintage Blackface, but rather a rich, almost plate-like density and bottom-end. I found myself turning the Dwell control further up than I expected and using the Mix control to dial in the wetness of the effect. There are awesomely weird sounds in Raw Silk mode when the amp was cranked with the Mix and Dwell past noon that edge on dynamic harmonic tremolo.
The speaker is a custom design in collaboration with Warehouse Guitar Speakers, and is available with Alnico or ceramic magnets. The voice coil is wound vintage style over paper (most modern speakers utilize plastics) and has an American style seamed cone tweaked to create a smoother and more open breakup than a typical American voiced speaker.
The inside of the amplifier is immaculate, and while I’m not of the persuasion to provide proof beyond visual confirmation, Charles states-
I believe an amps tone is shaped subtly but significantly by the quality of critical parts. Some capacitors and resistors can choke and smear the tone while some are too clean and end up sterile with no pleasing colorations. I tried tons of different caps and resistors and transformers of different prices and qualities and ended up with a pretty good mix. The blue sozo coupling/tone caps I use are built as replicas of the old blue molded caps used in vintage blackface amps, they allow for incredible tone. The resistors are a mix of my favorite carbon and metal film in various spots with a couple carbon comp thrown in for flavor. I ended up going with a paper wound vintage style transformer custom built by Magnetic Components Inc rather than the more common plastic wound modern style offerings. The plastic ones might have a little more detail and more of a hifi sound but the paper wound ones just had a way more pleasing sound to me overall. Very lush.
It is worth noting the Silktone amplifier is exceptionally quiet (a feat for a single ended, hand-wired turrent board circuit).
Single channel amp with no FX loop.
I’ve had the pleasure of playing through many of the big-name boutique amplifiers, whether at trade shows or through studio demos, and the Silktone amplifier easily earns its place in the upper echelon. By stripping away the circuit complexity and staging required to accommodate modern flexibility, the Silktone amplifier shows up as a reactive part of your guitar chain, giving more each step closer in the chain it is to your guitar. I’ve truly never had more fun with just a guitar, a cable, and an amp.
Chris Loeffler is a multi-instrumentalist and the Content Strategist of Harmony Central. In addition to his ten years experience as an online guitar merchandiser, marketing strategist, and community director he has worked as an international exporter, website consultant and brand manager. When he’s not working he can be found playing music, geeking out on guitar pedals and amps, and brewing tasty beer.