The Signature Series models are the finest work I’ve done in 30 years of amplifier design.   They are the product of extensive research and an uncompromising devotion to innovation and craftsmanship  in pursuit of a bold new voice in guitar amplification.   It’s a voice rooted in sonic purity and rendered with a vibrant, deeply resonant, and totally unconstricted sound  – like an acoustic instrument.   Every note is round and full,  with intense clarity and vivid dynamics.  

I build every amplifier myself at my Baltimore craft shop, working to the absolute highest standards of crafstmanship.   I craft the cabinetry myself from fine solid woods, assemble and wire all of the electronics on handmade turret boards, and even fabricate many custom parts such as knobs and other appointments.   

The Signature Series consists of three models:  the 12W Sugarland, the 28W Starwood, and the 45W Roseland.   These three models are very different from the designs I’ve done in the past and are loaded with innovation, artistry, and craftsmanship for a uniquely pure, natural, and resonant sound.   

Previous
Next

Innovation

Multi Voice Preamp

The innovative Multi-Voice preamp offers an incredibly broad palette of tones in a simple, sonically pure single channel design.  Using only bass and treble controls and no other switches or knobs, you can dial in anything from sparkling 60’s clean tones to fat, resonant tweed tones to plexi crunch, and everything in between.  This is a very different circuit from a traditional guitar preamp.  While a typical guitar preamp simply offers subtle tonal variations of the same general voicing, the Multi Voice preamp offers a wide range of distinct voicings because it varies both the frequency content and the gain / headroom in a more sophisticated manner, offering more headroom for mid-scooped clean tones and more gain for midrange-heavy overdriven tones.

Instrument Grade Cabinetry

The Signature Series cabinets are radically different from typical amplifier cabinets.   They are designed to perform like an acoustic instrument in which the natural acoustic properties of the solid wood components contribute to the sound and feel of the amplifier.   The result is a natural and unconstricted sound that’s uniquely deep, full, and resonant but also punchy and alive with intense clarity and definition.

Most amplifier cabinets are built with a plywood baffle board attached to the cabinet body with screws and cleats.  The Signature Series cabinets have a  multi-part solid pine baffle board with an integrated African Mahogany speaker flange which eliminates beaming, provides a firm mechanical connection to the speaker, and tunes the response of the baffle.  This baffle is bonded directly to the cabinet body without screws or cleats so that the entire cabinet participates fully in the acoustical behavior.  

This construction, along with a number of other details and treatments, add up to a  unique sound and feel – more like an acoustic instrument which fills the room with sound and every note blooms with unconstrained power and vivid clarity.

Custom Interstage Transformer

The Signature Series amplifiers employ a custom designed interstage transformer to balance the phase inverter and couple it to the output tubes.  Interstage transformers have  rarely been used in guitar amplifiers (because of the the high cost of high quality transformer) but they offer significant sonic benefits.  An interstage transformer retains symmetry in the phase inverter even in hard clipping.   This means that overdrive and distortion produced by the amp is rich in consonant harmonics for incredible clarity and note separation even when driven into fully saturated distortion.  It also means that the transition between clean and overdrive is extremely smooth and gradual and that the the raspy, ragged edge that most amps produce on the edge of breakup is eliminated.  Since the interstage transformer is dc coupled to the output tube grids, it also eliminates blocking distortion (the extreme “cutting out” type of compression most amps exhibit when pushed too hard).       

Innovative Master Volume

All Signature Series models are equipped with an innovative master volume circuit which goes beyond the limitations of other volume management schemes by preserving the harmonic balance and dynamic response.  The result is extremely transparent performance all the way down to bedroom volume.   Even at very low volume levels, the sound retains harmonic richness and presence without sounding buzzy or harsh.  It also introduces a hint of controlled compression on the leading edge of notes to preserve the tactile feel and response to your playing.    

Construction Details

The Signature Series are masterbuilt amps with obsessive attention to details.  As you would expect, I select only the finest components, but that’s really just the beginning.   Here’s a look inside at some of the details that make these amplifiers genuinely unique.    

The quality of the circuit layout is critical in achieving the best sonic performance and reliability.  For each model, I applied extensive R&D efforts to develop a circuit layout with ideal component placement and electrical/ grounding properties, then implemented the layouts with artistry and precision.  The result is unmatched sonic purity, extremely low noise, and rock solid reliability.  

I use vintage style, paper bobbin, layer wound transformers including a custom interstage transformer.

Cabinets are loaded with Celestion Alnico Blue or Alnico Cream speakers, depending on model. 

I fabricate custom footswitches to match the appearance of the amplifier.  They are finished in lacquered tweed with a bakelite top plate. 

Cabinets are crafted from solid Eastern White Pine with a unified body/baffle construction.

An 8-piece African Mahogany speaker flange tunes the response of the baffle and ensures proper acoustical coupling between the speaker and cabinet.

Cabinets are finished off with a custom handmade leather handle by Brookwood Leather of VA. 

Custom Fabrication

With the Signature Series, I made no compromises in implementing my design concepts.   I often found it necessary to make my own parts when off-the-shelf parts wouldn’t do.   Here are a few examples of custom parts I make myself to add refinement and distinction to my designs:

Currently available chickenhead knobs just don’t have a nicely refined profile like some of the vintage originals, so I developed the skills to make my own knobs.  I mold them myself in small batches.

I’m very particular about the way wires are routed inside the chassis.  I prefer that the wiring be tidy and well secured, so I designed these “wire tree” fixtures to help with wire routing.  This type of part isn’t available as an off-the-shelf item, so I’m molding them myself with shop-made molds.  

I make my own turret boards for every amp so I have total control over component placement and wiring.  This way, I can produce an electrically ideal layout for ultimate sonic purity and low noise.

I fabricate the rear control panels from a bakelite-like material which has a really nice look and feel.   I also silkscreen all faceplates, rear panels, and tube charts in-house.

Craftsmanship

The Signature Series models are built like no other guitar amp.   The craftsmanship and build quality are inspired by the work of fine instrument makers and are executed with care and precision.  Here are a few examples of the craftsmanship that is built into every Signature Series amplifier:

Component placement and wiring are performed with care and precision by designer Mark Bartel.
Cabinets are built with great attention to detail and meticulous craftsmanship throughout.
The cabinet body is formed with precision cut finger joints for superior strength and durability.
The cabinet is coated with a special recipe sizing compound which preserves and enhances the natural acoustic properties of the wood much better than paint. It is a rather impractical process, as the compound must be mixed for each batch and applied hot with a brush. However, the results are well worth it.
Upholstery operations are done with natural hide glue rather than contact cement. Unlike contact cement, hide glue cures to form a stiff bond which enhances and preserves the natural acoustic response of the cabinet.
A shop-built jig is used to stretch the grill cloth in two directions simultaneously while attaching it to the cabinet trim piece. By doing this, the grill cloth is properly and consistently tensioned, and the lines of the pattern are kept ruler straight.
The tweed covering material is coated with five hand-brushed coats of lacquer for a durable, attractive finish.
Chassis back panel pieces are made by hand from an attractive bakelite-like material.
Turret boards are custom made for each individual model design. Boards are cut, drilled, routed, polished, and cleaned in-house.
Each cabinet is glued up in a unified construction so that the entire cabinet participates in the acoustic response.
Footswitches are crafted by hand and upholstered in lacquered tweed to match the amplifier.
Previous
Next
Component placement and wiring are performed with care and precision by designer Mark Bartel.
Cabinets are built with great attention to detail and meticulous craftsmanship throughout.
The cabinet body is formed with precision cut finger joints for superior strength and durability.
The cabinet is coated with a special recipe sizing compound which preserves and enhances the natural acoustic properties of the wood much better than paint. It is a rather impractical process, as the compound must be mixed for each batch and applied hot with a brush. However, the results are well worth it.
Upholstery operations are done with natural hide glue rather than contact cement. Unlike contact cement, hide glue cures to form a stiff bond which enhances and preserves the natural acoustic response of the cabinet.
A shop-built jig is used to stretch the grill cloth in two directions simultaneously while attaching it to the cabinet trim piece. By doing this, the grill cloth is properly and consistently tensioned, and the lines of the pattern are kept ruler straight.
The tweed covering material is coated with five hand-brushed coats of lacquer for a durable, attractive finish.
Chassis back panel pieces are made by hand from an attractive bakelite-like material.
Turret boards are custom made for each individual model design. Boards are cut, drilled, routed, polished, and cleaned in-house.
Each cabinet is glued up in a unified construction so that the entire cabinet participates in the acoustic response.
Footswitches are crafted by hand and upholstered in lacquered tweed to match the amplifier.
Previous
Next
Component placement and wiring are performed with care and precision by designer Mark Bartel.
Cabinets are built with great attention to detail and meticulous craftsmanship throughout.
The cabinet body is formed with precision cut finger joints for superior strength and durability.
The cabinet is coated with a special recipe sizing compound which preserves and enhances the natural acoustic properties of the wood much better than paint. It is a rather impractical process, as the compound must be mixed for each batch and applied hot with a brush. However, the results are well worth it.
Upholstery operations are done with natural hide glue rather than contact cement. Unlike contact cement, hide glue cures to form a stiff bond which enhances and preserves the natural acoustic response of the cabinet.
A shop-built jig is used to stretch the grill cloth in two directions simultaneously while attaching it to the cabinet trim piece. By doing this, the grill cloth is properly and consistently tensioned, and the lines of the pattern are kept ruler straight.
The tweed covering material is coated with five hand-brushed coats of lacquer for a durable, attractive finish.
Chassis back panel pieces are made by hand from an attractive bakelite-like material.
Turret boards are custom made for each individual model design. Boards are cut, drilled, routed, polished, and cleaned in-house.
Each cabinet is glued up in a unified construction so that the entire cabinet participates in the acoustic response.
Footswitches are crafted by hand and upholstered in lacquered tweed to match the amplifier.
Previous
Next

Copyright 2018 Bartel Amplifiers LLC

All Rights Reserved