We posted a new online calculator for computing the frequency response of the plate bypass capacitor often used in high-gain preamps.
Try out the new calculator.
What lessons can we learn from Soldano's approach to high-gain preamp design? In his latest post, Pentode Press author Richard Kuehnel draws some conclusions based on a stage-by-stage analysis of the SLO overdrive channel.
Read more.
Amp Industry News
Mack Amps is shutting down its traditional dealer network to focus on direct factory sales. Owner Don Mackrill tells us that the savings, for both the builder and the customer, are substantial. Mack's best selling Gem head, for example, had an MSRP of US$547, quite a bargain for an all-tube design, but the current factory-direct price of only US$449 still generates a profit. Even with a typical 50-percent markup from wholesale, brick-and-mortar retailers are suffering from economic recession. As boutique amp builders and guitar players continue to cut costs, the red ink that flows from traditional sales channels is likely to continue. Read more.
Amplified Parts sales engineer Kurt Prange has written an excellent article on the selection and installation of spring reverbs. He includes listening tests for units manufactured by Accutronics, MOD, and Belton, and a handy table for estimating input and output impedance based on DC resistance. Read more.
Replaced a preamp tube lately? Back in the days of Eddie Durham and Charlie Christian it was easy - even the cocktail waitress could swap a big-socket octal in a Gibson BR-3. An over-sized chassis mounted upright on the floor of a completely open-back amp made the procedure trivial. Today we get tightly packed miniatures mounted upside-down behind the screws of a cabinet panel designed to make even a simple tube substitution seem like open-heart surgery. Fryette Amplification wants to change customer perception. The company's new Memphis 30 features front-mounted dual triodes that all but beg to be swapped out. Only the reverb driver, phase inverter, and power amp tubes remain off limits to cocktail waitresses. Read more.
It's been two years since Richard Kuehnel wrote here about Push-Pull without a Phase Inverter. Now Victoria Amp Company has become the first builder to put the unusual design into commercial production. The company's 10-watt VIC105 uses a pair of EL84 power pentodes instead of Kuehnel's 6L6 big bottles, but pushes the EL84's maximum cathode-to-heater voltage to the limit to achieve a more power efficient design. Read more.
Antique Electronics Supply, a major supplier to boutique amp builders through CE Distribution, has moved decisively into the amp kit retail market. AES has launched Mod Kits DIY, backed by its musician-oriented parts subsidiary Amplified Parts. Mod Kits DIY, in direct competition with some of CE Distribution's business customers, will market kits for amps and effects pedals directly to individual consumers.
In his article "Build a Custom-Printed Circuit Board" IEEE contributing author James Turner describes how to order professionally manufactured printed circuit boards online, even in single-board quantities, for under $20. He uses Eagle, a PCB design program from CadSoft Computer and BatchPCB, which consolidates individual projects onto a single large board and then cuts them apart when they come back from the factory. A two-layer, etched, drilled, and silk-screened circuit board costs just $2.50 per square inch. Read more.
BC Audio, on the other hand, hearkens back to the days before parts were forced into a 2-dimensional layout. Owner Bruce Clement says even turret and eyelet boards are out of the question. His Amplifier No. 7 line uses precision point-to-point wiring with 90-degree bends and 3-dimensional spacing reminiscent of vintage radio. Compare this No. 7 chassis photo with a World War I military set from the Western Historic Radio Museum.
Less than a year after Grid 1 launched its unique, battery-powered guitar amplifier, market forces have convinced the company to drop the retail price by more than 50 percent. The amp combines a 1U4 preamp tube with a highly efficient Class D power amp to produce 60 watts for 4 to 6 hours on lithium batteries, very impressive compared to all-tube battery amps. Consumers balked at the $3995 price tag, however. The entry-level price is now $1799.
Trinity Amps has begun commercial production of a 2-tube, single-ended "Tramp" that features a variable DC power supply and a swappable output tube for power stage distortion at a variety of volume levels. Despite the nouveau circuitry, owner Stephen Cohrs tells us he won't be offering it in a trendy, all-metal lunchbox. The low-power addition to the Trinity line-up is available only in a hand-crafted, finger-jointed, pine cabinet.
Little Walter Tube Amps is still building octal-based preamps, most notably in the Kelton Swade Vintage Combo, despite a dwindling supply of high-mu triodes in an 8-pin format. "I am buying up all the octals I can find," says chief designer Phil Bradbury. "I sure hope they get back into production soon." Recent 6SC7 inventory at Antique Electronic Supply: zero. We hope tube manufacturers are listening.
Eminence Speaker has launched a new power attenuation technology that varies loudspeaker efficiency at the turn of a dial. Fully cranked the control provides about 10dB attenuation, enabling a guitar player to create 50-watt sounds at a 5-watt volume level.
Extreme gain often demands extraordinary measures. For its new NATAS 100-watt head, Canadian builder Fortin Amplification takes a cue from high-end audio by including a regulated DC heater supply. Minimizing hum via silicon is limited to just the low-level preamp stages where it matters most. Read more.
Orange has launched its long-anticipated guitar amp with a built-in 64-bit Intel-based PC (4GB DDR2, 8 USB, 500GB HD, WiFi, GeForce 9300) and software (PreSonus Studio One, Acoustica Mixcraft 5, IK Multimedia AmpliTube 3, Toontrack EZdrummer Lite, and LickLibrary guitar lessons). The amp, unfortunately, is 100 percent silicon. Price tag: US$1499. Watch the Video.
James Brown, Chief Engineer at Kustom Amplification and former tech guru for Peavey, has begun moonlighting with his own company, Amptweaker. An engineer going solo is hardly news, but James has adopted a bold business strategy by appealing directly to the public for amplifier and pedal ideas. Famous artists expect a request like "make it a little brighter" to command the late-night insertion of a bright boost cap or less cathode bypass. Via Facebook, Twitter, MySpace, YouTube, and his website, Brown wants to give the same power to everyday consumers. Well, maybe not "late night," unless you count answering email. Read more.
Mention "outsourcing" and most people think of local jobs being exported to some far off country. For guitar amp builders, however, outsourcing usually means supporting your local cabinet maker, circuit assembly house, chassis fabrication shop, and parts supplier to focus on what matters most: great design. Henriksen Amplifiers doesn't sell tube amps, but the company deserves credit for openly publicizing its outsourcing strategy, and for employing highly skilled workers in Colorado, California, and Kentucky. Read more.
From his basement workshop in Michigan, MetroAmp owner George Metropoulos tells WJRT television reporter Marc Jacobson that he doesn't need to be in Los Angeles or New York to build amps for big name players like John Mayer. "It's a 21st-century business model all the way. It's Internet based with a lot of networking." Watch the video.
Budda Amplification is delivering leather-covered guitar amps to retailers. The company has teamed with boot designer Mark Nason to adorn 100-watt heads and 4x12 cabinets in fine Italian cow hide.
University of Illinois at Urbana-Champaign finished another successful semester of its Physics of Music Class. Professor Steven Errede continues to push the envelope on vacuum tube amplifiers, guitar pickups, and anything else in the signal chain that can be quantified by a well-equipped lab run by highly motivated students.
Eric Collins at Speedster Amplifiers has re-created Bluesbreaker grill cloth circa 1966 and is offering it cut-to-order to retail customers. Germino Amplification now installs the new grill cloth as a $400 per cabinet option.
According to the Fort Worth Star Telegram, Mouser Electronics has acquired an additional 18.9 acres adjacent to its 432,000-square-foot facility in Texas. We have no information whatsoever that the company is planning a new warehouse dedicated to carbon composition resistors, high-voltage polypropylene capacitors, and other components for guitar amp building, but let's start the rumor here!
Return of the rack? 3rd Power has ramped up production of a 2RU rack-mounted guitar amp. The model SV3015 has four EL34 power pentodes split into two independent channels. In contrast to conventional wisdom that players want "bright" and "normal" channels, 3rd Power markets a low-frequency enhancement technology it calls Push.
Fargen Amps is adding effects pedals to its business model. Founder Ben Fargen says he is forming Sonic Edge LLC to handle the new product line. A vintage overdrive box dubbed the "J&J" is set to launch this month.
Vox Amplification says that computer design and visualization software accelerated the time to market for its AC30C2 and AC15C1 models. According to Vox product development manager Dave Clarke, Autodesk Inventor and Showcase software reduces Vox's expenditures on physical prototypes and cuts the company's product development time in half. Boutique amp builders may not share Clarke's enthusiasm for point-and-click design, however, especially at a licensing cost of $6290 per workstation.