At Guitar.com, we always bring you the unbiased word on guitars. In this month’s installment of Technically Speaking, though, we’ll be indulging our bias—amp bias, that is. And, on that subject, who better to consult than the Bias King himself, Steve Wilson?

Wilson got his start as a production assistant before hooking up with Stevie Ray Vaughan. Wilson served as Vaughan’s amp & keyboard tech until the guitarist’s tragic death in 1990. Since then, through his own Ambient Sound business, Wilson has serviced or reworked amps for Marty Stewart, The Black Crowes, Cinderella, John Hiatt, Lyle Lovett, and many more. Wilson has also designed and developed his own product, the Bias King, to help amp owners keep their tubes in check. And, these days, when he’s not behind an amp, Wilson’s out on the road with the Kentucky Headhunters, serving as the band’s sound technician and friendly DVD supplier.

Wilson recently took part in an e-mail interview with Guitar.com, and we’re happy to share with you the Bias King’s responses.

Guitar.com: Where did you grow up?

Steve Wilson: Louisville, KY.

Guitar.com: When did you first start becoming interested in music and, specifically, playing guitar?

Wilson: I was in high school. I remember hearing TJW [Tony Joe White] do “Polk Salad Annie,” and that was all she wrote! J

Guitar.com: Did you play in any bands?

Wilson: I played in a band all through high school and dropped out of Speed Scientific School at the University of Louisville to go on the road and play rock n’ roll. It would be called “Classic Rock” now –Allman Brothers, Free, Bad Company, ZZ Top, etc.

Guitar.com: What was your own setup back then?

Wilson: Started out with a White Gibson Les Paul Custom (SG style) through an Acoustic 150 on a 4x12 cane front Marshall cab – still have that stack! Went to a Super Reverb on that same cabinet, but switched to a sunburst Les Paul Deluxe. Then, I found a 100W Marshall stack (the first one in Louisville!) with two cane front “greenback” cabs in the newspaper. Stayed with the Les Paul, but the 100W head was too much. Switched to a ’74 50W head with the two cabs. About that time, I switched to a ’64 Dakota Red Strat that I used until I quit playing in ’81. That’s where I stayed for the duration.

Guitar.com: How did you transition from playing in bands to serving as amp tech? What interested you about becoming an amp tech?

Wilson: I love the smell of solder in the morning. :-) I had always been a “techie.” My brother and I would build lighting controllers and “flash pots” out in the garage. I always built and hooked up the PA for our band. I recall one time having all three of our Marshall heads apart (the other guitarist had a pair) 30 minutes before the show started, installing a “new” master volume circuit [that] I came up with after studying the schematic. In this “novel” approach, I took the signal from the treble wiper to a pot and turned down the signal going into the phase inverter. I guess I found out that I would just as soon solder as play guitar.

Guitar.com: Did you have any formal background in this stuff or was it all “learn-as-you-go”?

Wilson: I had no vacuum tube background at all. All the college info was transistor-related. Ohm’s Law and Kirchoff’s Current Law are pretty universal. All the tube stuff came from old Navy electronics books [that] I found at flea markets or hamfests. The big flood came when I found the Radiotron Designer’s Handbook: Volume 4. I already had Volume 2, but there’s no comparison to the big red book.

Guitar.com: What was the biggest challenge in your early days as an amp tech?

Wilson: It took me a while to understand just how much the Screen Grid affected the operation of the tube. Once I got that, it seemed much easier.

Guitar.com: How did you come to work with Stevie Ray Vaughan?

Wilson: I was working as a production assistant for a concert promoter at a Jeff Beck/SRV show and met Rene Martinez backstage. He had a blackface Fender Vibroverb apart that had some problems. I offered assistance and gave him my card. When Cezar Diaz left to go with Bob Dylan, I was called to replace him.

Guitar.com: What were your responsibilities?

Wilson: I was Stevie’s amp tech and Reese Wynan’s keyboard tech. During the show, I would watch Reese and Tommy (Shannon), in case they needed anything.

Guitar.com: Describe a typical day with Stevie on the road.

Wilson: I would set up the keyboards and bass rig first. Then, I would break out the rolling shop. I had a scope, signal generator and dummy load in a rolling rack full of tubes and parts that I carried. I would have to replace all the arced sockets in the Marshall Major and any shorted tubes or burned screen resistors. Stevie always closed with “Voodoo Chile” and would look over his shoulder at the Major to see if the pilot light was still on, ‘cause it would blow up about every other night.

Guitar.com: What amps was he using when you were with him?

Wilson: When I started, he had a 1-15 Vibroverb driving a Vibrotone, a Dumble Steel String Singer on a 4x12 EV loaded cab, a 200w Marshall Major on a 4x12 EV loaded cab, and a pair of blackface Super Reverbs with the two bottom speakers replaced with EVs. When we did The Tonight Show, Fender brought him a pair of the new reissue ’59 Tweed Bassmans. I still have the original Fender tags off of those amps. (This was the same time Larry Brooks was taking micrometer and caliper measurements from the neck of Stevie’s “#1” Strat that later became the SRV signature model) He used these new Bassmans in place of the Supers from that point on. These were all hooked up with a passive splitter that was simply a box with several ¼” jacks wired in parallel. The signal loss was never a problem. Stevie didn’t like distortion unless he created it. He wanted to play loud and clean. That’s why he always plugged into the low sensitivity inputs on the Supers.

Guitar.com: Did Stevie himself typically sound check?

Wilson: Always! He loved to play. He even Super Glued his callouses back on when they would come off. That’s devotion!

Guitar.com: What were some of the biggest challenges during sound check? What were the typical problem spots?

Wilson: They always seemed to go well, other that a bit of monitor feedback. Stevie always wore the hat, and that would scoop the signal straight back to the wedges! (Bless you, Randy! I know that was frustrating!)

Guitar.com: Did you guys spend a lot of time refining his sound?

Wilson: He could play through any rig and still sound the same. We once spent a whole day working on the Supers. He was hearing some distortion and we were trying to get it out. Stevie had a great ear! He would tell Rene that one of his speakers was bad, and we would check it out. He was always right on. We had a fly date in Alaska where the gear had to be rented. Stevie played through a 4x12 Marshall cab loaded with Celestions. After the show we were walking around the ice, and I asked him how he liked the Celestions. He said, “What did you think?” I told him that I heard some things I liked about them. He agreed. He liked to get your opinion first, before he gave his. I guess that cut down on the possibility of being surrounded by “yes” people that just agree with everything.

Guitar.com: What was your most memorable concert with Stevie?

Wilson: It had to be Stevie’s last show at Alpine Valley. There was, as corny as it may sound, an electricity in the air that night. Everyone was even talking about it after the show.

Guitar.com: Let’s focus on amps for a bit. Tube vs. solid-state? Any thoughts? ;)

Wilson: It’s actually pretty hard to tell the difference until they distort. That’s when the “magic” happens for guitar. A mentor of mine once told me that solid-state equipment ran on “smoke.” When I questioned him on that, he told me that when you let the “smoke” out of a transistor, it would quit working. I’ve always heard “solid waste” when folks refer to transistor gear, but I just retired a pair of consecutive number Mac 60 mono blocks in favor of some solid state Carver Silver Seven-t monoblocks. The Carvers outperform the Macs in every area. I need to sell those Macs on E-bay!

The natural compression and harmonic content are very musical with tubes. From a repair and mod standpoint there’s no comparison. The tube stuff is just so easy to get around in. You usually don’t need any service info or part numbers. Can’t do that with a solid-state piece. The tube downside might be the weight from all the iron in the transformers. I just worked on an SVT for NRBQ (that’s a lot of initials!), and I could barely lift it up on the bench!

Guitar.com: Who should use tube amps and what should someone look for in a good tube amp?

Wilson: Anyone looking for an amp that will “play” back should check out a tube rig. The bounce from the compression makes it seem like the amp is responding to your touch in an almost human way. I would pick an amp that sounds good clean. It’s harder to make a good sounding “clean” amp than a “bumble bee in a box”.

Guitar.com: What are some of your favorite tube amp models and why?

Wilson: Any pre-’74 Marshall is the stuff! In your face and takin’ names. I really like the BF Super Reverb and the tweed Deluxe. The 1-15 tweed Pro from the late 50’s is a great sounding amp, as is the ’59 tweed Twin and Bassman. There are just so many great amps out there that any of them can hold their own as long as they are in good working order and set up correctly with good speakers.

Guitar.com: What is the most exotic amp you’ve ever worked on?

Wilson: I have tweed Gibson Stereo Trem-a-Vibe that had a leaky coupling cap. Now it sounds great. A 15 in the middle and a 6x9 on each end facing out. The straight sound comes out of the 15 and the tremolo bounces back and forth between the 6x9s.

Guitar.com: Tell us about Ambient Sound…

Wilson: I started Ambient Sound in 1978 or ’79. I was playing in a regional band and started doing mods and repairs on Marshalls along with some audio consultation. I needed a company to order parts through, so I set it up. Now we make the Bias King products and have a couple of other projects in the wings.

Guitar.com: Can you explain for our readers the concept of amp bias? How does bias affect the sound of a tube amp and how can it affect tube life?

Wilson: WARNING! Shameless plug to follow… The easiest way would be to check out this web site: http://www.biasking.com and click on the “What is the Bias and How Does it Work” link.

Guitar.com: When and how did you first come up with the Bias King idea?

Wilson: I’m a tube Hi-Fi buff, and a lot of the old tube Hi-Fi amps had a resistor in the Plate or Cathode to measure the bias current and a set of test points for easy meter access. I didn’t want to modify the old classic gear with holes for meter access points, so the socket idea with a meter attached came to mind. I’ve been making these ever since I can remember working on the stuff, but they looked a lot different! Big round meters the size of a ’57 Buick were the norm. Tom Keifer from Cinderella actually had me make him one with the old style meter, just ‘cause it looked so darn cool! I spent 3 days in the studio with Tom and watched him play a killer old Tele through a 200W Marshall Major (he has about 6!) with four 4x12 cabs. It was the most incredible sound I have ever heard! He would even check the bias between takes to make sure the tone hadn’t shifted.

Like anything else, necessity is the mother of invention. If you don’t want to drill holes in your mint condition ’72 100W Marshall Super Lead with Green Tolex to add meter test points, and don’t want to take the head out of the chassis every time you just want to check the bias, you gotta’ do something! :-)

Guitar.com: Typically, how often should one bias an amp?

Wilson: Every time you change output tubes is a minimum. If you want to go further, you could check it every week, every day, or between songs. I never check mine unless it’s a new set of tubes, or the amp starts sounding different. A quick bias tweak will usually set it straight.

Guitar.com: Where is Bias King available?

Wilson: There are two models. Both are only available through dealers such as: Antique Electronic Supply [http://www.tubesadnmore.com], Mojo Music Supply [http://www.mojotone.com], New Sensor Corp. [http://www.newsensor.com], The Tube Store [http://www.thetubestore.com], and TecSol [http://tec-sol.com/bias_king.htm].

Guitar.com: Can you name some of your more famous Bias King customers?

Wilson: We’ve sold Bias Kings in six countries, so far. Fender, Marshall (Korg), Trace-Elliot, Belov and Ampeg have all ordered Bias Kings for the repair bench. There are a ton of players out there with them from Billy Gibbons and Brian Setzer, to the Kentucky Headhunters and Cinderella – and all points in between. You DO have one or two yourself, don’t you? ;-)

Guitar.com: Any plans for future Bias King products or enhancements?

Wilson: We just redesigned the custom molded cable and power supply this year. I think we’ve squeezed as much juice from this grape as we can get. We’ve got a couple of other projects on the back burner, and when the Headhunters get too old for all this foolish traveling, I’ll have time to work on them! :-)

Guitar.com: Speaking of the Headhunters, how did you get together with them?

Wilson: I had known the guys for years from playing around here and worked on Greg [Martin]’s amps. After Stevie’s accident, Greg called and said, “Come hang out with us on the road and chill.” It felt so good I never left! :-)

Guitar.com: How often do you go out with the guys?

Wilson: We usually do the weekend State Fair thang or a festival along with a couple of 3-4 week runs thrown in throughout the year.

Guitar.com: What are your official responsibilities?

Wilson: I mix the FOH and take care of any technical issues that may crop up, but my main job description is provider of DVDs for the bus! BTW, be sure and check out the new Headhunter CD called Soul!

Guitar.com: One final question: When you’re out on the road and working on amps, what separates a good day from a bad day?

Wilson: CATERING!