How to Create a Bluesy Slide Guitar Sound on an Electric Guitar: A Comprehensive Guide

Summary

This guide distills the art of crafting an authentic bluesy slide guitar sound into four critical operational stages—each designed to help both beginners and intermediates capture the raw, soulful tone of classic blues. By systematically addressing equipment selection (from the right guitar body to slide materials), string tuning for fluidity, core finger techniques, and tone-shaping with effects, players gain actionable frameworks: whether chasing the gritty growl of a bottleneck on a Les Paul, the warm sustain of a chrome tube slide on a Gretsch hollow-body, or replicating BB King’s signature glides with precise EQ and compression. Practical examples anchor abstract concepts, like Muddy Waters’ tuning secrets or DIY slide lubrication, ensuring tangible progress with every practice session.

1. Equipment Setup and Preparation

1.1 Guitar and Amplifier Selection for Slide Tone

1.1.1 Choosing the Right Electric Guitar

When selecting an electric guitar for slide work, two primary considerations shape tone: body construction and neck profile. Solid-body guitars like the Gibson Les Paul (mahogany body with mahogany neck) excel for raw, focused grit, as their rigid woodframe minimizes feedback while maximizing string resonance under sliding motion. The sleek mahogany neck on a Les Paul measures ~0.875”-0.9375” at the 1st fret, providing a smooth platform for glass bottlenecks or metal slides to glide without excessive string noise. Hollow-body guitars, such as the Gretsch Streamliner G2622T (maple top with birch body), offer a warmer, more nuanced voice by leveraging their resonant hollow chambers. The Gretsch’s thicker maple neck—typically 1.0” at the 1st fret—complements heavier slides (0.3”+) without deadening tonal complexity, ideal for soulful slides in open tunings. A good rule: test neck thickness with a dry-wipe between the thumb and index finger when lightly pressing the fretboard; look for a profile that allows the slide to rest ½” from strings without pinching the palm.

1.1.2 Amplifier Pairing for Bluesy Slapback and Warmth

Amp selection directly translates to slide tone character. Tube amps (e.g., Fender Blues Junior IV) deliver the quintessential “50-80% power” saturation for blues: pushing an amp to 60% of its wattage generates subtle harmonic overtones (think B.B. King’s “Lucille” grind), while solid-state amps (e.g., Roland JC-120) offer cleaner definition, better for precision slides but less organic grit at full volume. Speaker cabinet choice is critical: Celestion G12-65 “V” speakers deliver a vintage 65-watt “V”-shaped frequency curve (enhanced midrange at 300-500Hz, perfect for growl without harsh treble). Pair with a 2x12” cabinet to capture slapback reverb decay; a single 1x12” (e.g., 1x12” Celestion G10) works for country slide but risks muddiness in blues mixes. For slide warmth, aim for preamp tubes (5881s or 12AX7s) rated for subtle overdrive—avoid 100-watt “brutal” amps if after a warm, controlled growl.

1.2 Slide Tool and Accessory Setup

1.2.1 Slide Materials: Tone Variations

The slide—often an overlooked but foundational element—shapes timbre dramatically. Glass bottlenecks (e.g., empty amber beer bottle) produce muted, earthy tones with natural harmonic coloration, ideal for Deep Delta blues (Muddy Waters’ signature). Their lack of sharp edges creates friction-born overtones that pair well with solid-body guitars. Chrome-plated metal tubes (0.5” diameter) offer a brighter, more sustained tone, perfect for hollow-body slide with blues choruses (e.g., Gretsch’s Nashville-style twang). Thickness dictates tonal range too: a 0.125” diameter glass bottleneck (thin) works on baritone guitars for piercing high-end growl; a 0.375” chrome tube (thick) warms low-end notes on tenor or electric steel guitars. Test thickness by pressing the slide against a string—if it bends the note flat immediately, the diameter is too large; if it slips freely, too small.

1.2.2 Slide Positioning and Comfort

Proximity to the fretboard is key: positioning the slide ⅛–1 inch from the strings (measure with a 5/32” rule for precision) ensures notes ring clear without muting all volume. Too close (＜½″) traps strings, creating buzzing; too far (＞1″) causes drop-off in sustain. For “growl” effects, tuck the palm of the picking hand against the guitar’s body near the strings, applying light downward pressure to mute overtones and accentuate gritty harmonics (Muddy Waters’ trademark technique on “Hoochie Coochie Man”). Conversely, a relaxed palm position (open, fingers hovering) enhances warmth for ballads. Pro tip: Polish the slide with fine steel wool before use to remove surface imperfections; if using a glass slide, lightly apply petroleum jelly to the metal neck for smoother glides during long sessions—this prevents tone-dulling “sticking” while reducing fretboard wear.

2. String Tuning and Intonation Adjustment

2.1 Open Tunings for Slide Fluidity

2.1.1 Standard Tuning Adaptation (EADGBE)

Standard EADGBE tuning forms the foundation for blues slide proficiency, but requires subtle fretboard optimization to unlock fluidity. For smooth slide bends, players often lower open strings by targeting either the 5th fret of a root string (e.g., bending the high E string to G at the 5th fret) or freeing up tension on the open 3rd string (G on the E string, D on the B string). Muddy Waters’ iconic slide style exemplifies this: on his D string (5th string, default 10th fret octave tuning), he shifted the open G note to the 3rd fret (a minor 2nd flat), creating the distinctive “drunken” Gb to G natural pullback that defined tracks like “Hoochie Coochie Man.” This subtle microtonal adjustment works by leveraging the D string’s 12th fret harmonic (a perfect octave shift), allowing the slide to land 3 frets below—amplifying the low-end growl while maintaining harmonic structure.

2.1.2 Alternative Tunings for Mastery

Pushing beyond standard tuning opens doors to chordal simplicity and tonal versatility. Open G tuning (DGDGBD) simplifies blues power chords by arranging the root strings (B, D) open, allowing barre chords at the 3rd fret (common on Gretsch guitars). For instance, the open 5th string (G) in DGDGBD creates a low-note “rumble” that pairs perfectly with the slide: barring the 3rd fret across all strings forms a G7 base (G-B-D-G), requiring minimal chord changes. Meanwhile, Dropped D tuning (DADGBE)—lowering the 6th string to D while keeping 5th as F#—adds a resonant open 2nd string (A). This A string becomes the “slide lane,” allowing players to glide vertically without re-tuning: slide from A (open 2nd string) across to B (1st fret) and C# (3rd fret), creating the staggered “staircase” pitch that defines slide blues riffs like “Cross Road Blues.”

2.2 Intonation and Compensation for Smooth Slides

2.2.1 Fretboard Intonation Check (12th fret tuning benchmark)

Accurate intonation is critical for slide consistency across the fretboard. The 12th fret acts as a universal reference: in equal temperament tuning, every string’s 12th fret should be a perfect octave above the open string. To verify, tune the open G string (6th) to G on a chromatic tuner, then place the slide on the 12th fret of the G string—if the pitch rises to G, intonation is correct; discrepancy (e.g., A-flat) signals compensation needs. Stray from equal temperament, and the blue note (e.g., 5th fret F on the A string) will clash: sliding into a fret with flat intonation causes a “dead spot” where the note loses resonance. Guitarists aiming for bluesy microtonal bends must first ensure the 12th fret aligns with the harmonic series, eliminating unexpected drop-offs mid-slide.

2.2.2 Slide-Related Intonation Issues & Fixes

Two factors define slide intonation conflicts: equal temperament’s precision versus bluesy microtonal expressiveness. Equal temperament forces all 12 notes after the 12th fret into uniform ½-step increments, but blues slide craves more nuanced bends (e.g., a G to Gb slide on the D string calls for a 10-cent flat adjustment, not full semitone). Fixes involve compensated fret slots—luthiers mill bass strings 2-3 cents flatter (to counteract the “slack” natural tension of heavy slides), while treble strings may need smaller adjustments. Players can also manually refine by honing bends: when sliding from G to G# on the B string, an equal-tempered bend requires 20 cents; a bluesier phrasing might use 40 cents, creating a soulful vibrato effect. The key is reconciling both systems: start with 12th-fret benchmarks, then adjust microtonal overtones by 10-cent increments (via fretboard filing) to match bluesy lead phrasing.

3. Core Techniques for Bluesy Slide Fingering

3.1 Fretting, Picking, and Sliding Synergy

3.1.1 Hands-Free Slide Movements

True blues slide transcends mechanical gliding—it becomes an extension of the hand’s natural motion. The “fretless concept” eliminates the need for strict fretting by leveraging string tension: on the 2nd string (B string in standard tuning), sliding from G to Ab demonstrates this principle perfectly. Players press lightly over the 3rd fret, allowing the slide’s edge to catch string tension, creating a seamless pitch bend without lifting fingers off the neck. For vibrato-free slides, hammer-on/-pull-off techniques act as silent vibrato alternatives: a hammer-on at the 10th fret (from the 9th) on the 6th string (E) for G note warmth and a pull-off from G to F# at the 8th fret for controlled descending tension mirror classic Robert Johnson’s bottleneck phrasing, where such movements maintained vocal quality without added effects.

3.1.2 Palm Positioning for Volume Control

The palm is the unsung architect of slide dynamics, a tool that shapes growl and aggression. For light palm positioning (fingers hovering over bass strings), the slide’s wood or metal edge rests near the bridge, creating subtle string contact that generates a “growl”—think of Johnny Winter’s slide on “Rock Me Baby,” where his palm grazed the A string (5th string) to introduce grit without muting. Conversely, aggressive palm muting on bass strings (low E or A) requires firmly pressing the palm against the upper bass strings, reducing string decay while accenting slides into 7th chords. This technique is vital for tracks like “Key to the Highway,” where bass string growl syncs with a muted slide to sharpen the harmonic attack. The palm’s angle key: 45° to the strings for controlled sustain, 90° for percussive muting, avoiding the dead spot at 0° (excessively light palm) or 180° (over-muted “thwack”).

3.2 Chord Theory for Slide Blues Progressions

3.2.1 I-IV-V Slide Blues Foundations (E-A-B progression example)

The bedrock of blues-slide theory lies in the I-IV-V framework—translated to slide, it becomes a study in open voicing mastery. Taking the E-A-B progression: instead of static fretted chords, open chord voicings act as anchors. For example, the G major 7 chord on slide guitar (E-A-B foundation) often features the open 6th string (E) playing the root, with the slide bar at the 3rd fret of the 2nd string (A) and 5th fret of the 1st string (B), creating a lush G7/E7 transition. This mirrors Peter Green’s Fleetwood Mac work, where the open high E formed the “hover” note for smooth I-IV-V movement. The key: maintain the 1st string’s A open over slide, while the 2nd string’s 3rd fret (C#) and 5th fret (E) anchor the chord shifts smoothly without drop-offs.

3.2.2 Slash Chord Scales for Lead Lines

Slide lead lines demand tonal agility, answered by slash chord scaling. Over dominant chords (e.g., A9), the D mixolydian scale excels: rooted on D, it spans mixolydian’s tonic (D) through submediant (F#) to flat7 (C), a structure that glides naturally under slide bends. BB King’s “Sweet Little Angel” exemplifies this: using an A9/SG chord (A-C#-D-E on slide) paired with D mixolydian, he slides from A7’s 12th fret (over the 5th string) down to D (mixolydian’s root), leveraging G as a passing tone for seamless lead between A9 and Bb13. By pairing dominance with specific modes—Dorian for minor bends, Lydian for upward slides—players avoid mechanical scales, instead creating phrases that “breathe” like vocal lines, a technique Eric Clapton mastered on “Crossroads” with B7b9 chords over E phrygian slide.

4. Amplifier Effects and Post-Processing

4.1 Distortion and Saturation for Gritty Tone

4.1.1 Distortion Pedals for Vintage Blues Fuzz

• Tube Screamer vs. Pro Co Rat for Delta blues: The Tube Screamer’s germanium diode-tinged warmth (e.g., JCM800 amp mid-gain at 70% power) delivers smooth, singing fuzz ideal for Robert Johnson-style bottleneck, while the Rat’s silicon clipping produces brutal, aggressive grit (think Stevie Ray Vaughan’s overdriven tones). The contrast shines in Delta blues riffs: Johnson’s “Last Fair Deal Gone Down” uses a Tube Screamer’s clean headroom boost to mimic vocal vibrato, while Vaughan layered Rat drive for “Texas Flood”’s distorted midrange aggression, creating a tonal spectrum from honeyed growl to raucous intensity.

• Crank amp to 70% power (avoiding clipping at peaks) and mid-range boost (300-500Hz EQ cut/boost) replicates the tube “breakup” that defines Vintage Delta tones. Players dialing in 300-500Hz midrange emphasize the chest voice frequency of real blues vocals, as this range aligns with amp’s natural harmonic saturation and slide-induced string overtones.

4.1.2 Effects Pedal Chain Synergy

• Overdrive → Compressor for sustain: A Boss OC-3 octave + Blues Driver serves as a blueprint. The Blues Driver’s soft-clipping boost (at 2 o’clock gain) feeds into a Boss CS-3 compressor’s slow attack (20ms) and 4:1 ratio, creating “invisible sustain” that preserves note decay while taming dynamics. This chain mirrors Muddy Waters’ approach on “Hoochie Coochie Man,” where overlapping overdrive-compressor interaction thickened his bottleneck slides, avoiding the “washboard” flatness of unprocessed amplifiers. The octave layer adds 2 bass strings of octave-down sustain, replicating the “vocal octave” sound essential for traditional blues.

• Alternative chains: For more subtle grit, a MXR Distortion Plus (hard clipping) precedes a TC Electronic Squeeze compressor (1.5:1 ratio) to retain note definition while adding harmonic weight—a common choice for slide players who use volume swells between phrases.

4.2 Reverb and Delay for Authenticity

4.2.1 Room vs. Plate Reverb: 1.2-1.5 Second Decay

• Room reverb (e.g., Fender Rumble Stage’s 1.8s decay) adds intimate, hall-like depth, perfect for small club tones but risks tonal muddiness on smaller stages. Plate reverb (Yamaha SPX-90’s “600ms plate”) is preferable for vintage authenticity, with 1.2-1.5s decay replicating the shadowy, cathedral-like resonance of pre-digital recording studios. The plate’s smooth decay curve enhances the “bleed” between chords, as heard on B.B. King’s recorded tones—his 1978 stage rig used a 1.4s plate reverb to mimic the vinyl recording’s spatial warmth, while modern players like Gary Clark Jr. blend 80% plate with 20% room reverb for live authenticity.

• EQ tweak: 600Hz boost (3dB) in plate reverb settings neutralizes high-end harshness (8kHz) to focus on the “vocal mid” that makes slide lines feel like storytelling.

4.2.2 Slapback and Delay for Vintage Depth

• 1/4 note delay (e.g., 120BPM = 300ms per note) creates a “glassy” vintage depth. Pair with 15-20% feedback to replicate the “echoey” slap effect on early Memphis soul records. For slide depth, use Boss DD-500 with “70% wet” wet/dry control, bypassing 1/4 note delays on the bridge pickup for a “duet” feel.

• Slapback delay (100-150ms decay) pairs with 3rd string (G) slide runs in keys of E and A, mimicking the “walk-up” echo on Howlin’ Wolf’s harmonica slide lines. The 1/4 delay’s syncopated feel (e.g., 16th-note taps) adds staccato depth without overwhelming the slide’s pitch accuracy.

• Avoid overcomplicating: Most blues legends capped delay at 20% feedback, as excess feedback (“howling room”) destroyed the “conversation” between slide and vocals—a lesson learned from Stevie Ray Vaughan’s refusal to use feedback-heavy effect pedals on studio recordings.

5. Tone Shaping with Effects and Gear Adjustments

5.1 Post-Guitar Signal Chain Upgrades

5.1.1 Essential Gear Picks for Professional Tone

A DI box + preamp functions as the ideal post-guitar hub for stage-to-studio transitions, particularly the SPL Transient Designer. This unit’s dual benefit—cleanly capturing string attack dynamics while adding subtle harmonic enhancement—bridges the gap between raw guitar tone and recording-ready polish. For blues slide, where note separation and sustain matter, pair the DI with a compressor set to a 4:1 ratio with a slow attack (20-30ms). This configuration preserves the percussive snap of slide glides (e.g., when sliding from B3 to A7 roots) while smoothing out volume fluctuations, ensuring consistent tone even during dynamic vocal accompaniment.

5.1.2 DIY Slide Guitar Modifications

Elevate slide comfort and tone with two practical upgrades. First, applying a light coating of Teflon or graphite dry lubricant to guitar strings (prior to sliding) creates a friction-reduced surface, allowing smoother notes and reducing string “stutter” during bar or bottleneck slides. Second, magnetic pickups built for slide-specific use, such as Gibson’s magnetic slide bar, integrate by clamping to the guitar’s control cavity, eliminating the lag between slide movement and pickup signal. The Gibson slide bar review highlights how its precision-finger design adds 2dB extra midrange warmth compared to wooden slides, perfect for replicating BB King’s 1970s guitar tone.

5.2 Real-World Blues Slide Tone Examples

5.2.1 Step-by-Step: Replicating BB King’s “The Thrill Is Gone”

BB King’s signature tone relies on two key elements. For the B3-A7-E7 progression, after strumming the open-E chord (6th string’s 12th fret), slide upward along the 12th fret from E (6th string) to F (half-step up) by pressing the slide onto the fretboard’s crown edges, ensuring no wrist twist. To mirror his “bend and release” technique, practice 100% slide—hinging only the finger, not the entire wrist—maintaining constant pressure to avoid pitch deviation. This method preserves the seamless transition between note decay and vocal-like vibrato on string bends, as seen in the track’s iconic opening slide runs.

5.2.2 Recording Studio Blues Slide Setup (EQ Details)

In a studio setting, EQ processing can make or break slide clarity. Boost 500Hz by 4dB to emphasize the slide-induce string overtones’ “chest voice” quality, aligning with vocal pitch projection. Conversely, cutting 8kHz by 2dB reduces high-end harshness, preventing the overfrequent “slide squeak” that muddles tone in close-mic’d studio recordings. Pair this with a subtle 200Hz boost (≤2dB) to round out the guitar’s lower midrange growl, ensuring the slide’s growling harmonics sit cleanly in the mix. These final touches refine the already-built groundwork of blues slide tone, ensuring both live authenticity and studio-grade polish—turning each slide into a story of grit, warmth, and emotional resonance.

6. Fixing Common Slide Guitar Mistakes (Future Extension)

6.1 Buzzing and Uneven Tone Issues

Slide guitarists often encounter buzzing strings or inconsistent tone when the slide or playing mechanics interfere with proper string contact. The first troubleshooting step involves inspecting fretboard contact, especially the area around the 7th to 12th frets where most slide passages reside. If strings buzz against frets during low slide positions (e.g., bottleneck slides on open chords), check for fret crown wear – worn fret edges create uneven surfaces that catch the slide or string mid-glide. Replacing these frets with rounded, flat-top replacements (available at luthier shops) restores the smooth, consistent contact needed for even tone across all slides. A second common culprit is string tension inconsistency. Slides with excessive tension or improper placement on the string (e.g., dragging the slide too far under the string instead of resting on top) can cause the string to "jump" or "stutter" between frets. Ensuring the slide is centered over the fretboard's crown rather than pinching strings against metal capo-like edges prevents this. For beginners using metal bars, testing slide-on tension by lightly pressing the slide against frets and comparing string "playability" with lubricated strings (e.g., using a graphite-finished bottleneck) can reveal whether friction or tension is the issue. Lastly, pickup alignment for slide often goes unaddressed—a magnetic pickup misaligned (e.g., too close to high E string) may dampen string vibrations, causing "choked" tone. Reconfiguring pickup screws to keep the slide-induced harmonic content (overtones) in the mix, or retrofitting a vintage-style humbucker with wider pole pieces, can optimize vibrational transfer. For acoustic-electric conversions, using a capacitive pickup system with adjustable string height (e.g., Fishman Presys II) ensures that slide pressure doesn’t trigger unwanted feedback or ground hum, resolving uneven tone between adjacent notes. With these fixes, slide transitions will consistently maintain both resonance and clarity, laying the foundation for flawless, professional-grade slide performances.

7. Advanced Slide Techniques (Future Extension)

7.1 Tapping and Travis Picking for Slide Mastery

To elevate slide guitar proficiency beyond basic bottleneck glides, integrating tapping and Travis picking creates dynamic, multi-dimensional blues improvisation. In blues tradition, these techniques expand the single-movement slide approach into a rhythmic, note-bending art form, ideal for songs demanding both percussive and melodic complexity. Complex fingerpicking patterns for blues improvisation: When combined with slide, Travis picking (alternate bass and high-string arpeggios) introduces syncopated basslines and rapid up/down strums while maintaining smooth slide transitions. For example, a G7 blues progression paired with Travis-style arpeggios (e.g., G root on 1st string, B bass on 6th string, High E 3rd fret B note) creates a "walking bass" effect that mirrors the fluidity of jazz-improv. Fret-hand tapping adds percussive accents midway in the progression—tapping the 12th fret’s open string (E) while sliding up to the 14th fret on the D string (A flat) produces a percussive "slap" that contrasts the slide’s drone. A critical element is rhythmic coordination between the picking hand (travis thumb/ fingers) and slide hand: the thumb alternates bass notes while the fingers perform rapid 16th-note runs on the higher strings, with the slide executing targeted pitch-bends (e.g., bending a C note on the 12th fret to D by sliding 2 frets on the G string). Beginners should practice with metronomes at BPM 60, isolating the slide’s role as the melody while the picking hand establishes a steady acoustic-guitar-inspired Travis rhythm. For electric guitarists, a clean amp setting with subtle delay (200ms) helps reinforce the complex layers, and light palm muting on bass notes clarifies the interplay without muddying the slide’s tone. As skill progresses, integrating double-stocked Travis patterns (fret thumb and index finger plucking adjacent strings) with slide bends (e.g., from E to E♭) introduces harmonic tension, mimicking the call-and-response structure of Chicago blues sessions. This requires mastering silent slide movements—using the picking hand’s fingers to pluck strings without disrupting the slide’s position, a technique best practiced on slow tempos with a metronome, gradually increasing speed while maintaining string contact for unbroken tone.

8.1 Iconic Players and Setup Breakdowns

Muddy Waters, a towering figure in Chicago blues, revolutionized slide technique with gear that blended raw Delta grit and electrified Chicago edge. At the center was his 1952 Gibson ES-350T hollowbody, selected for its resonant bass response—a necessity for cutting through brasseries while maintaining the warmth of delta blues. He paired this with a National resophonic guitar (later swapped for a metal bottleneck in studio recordings), favoring a chrome-plated brass slide (0.250”) for its bright, piercing tone. For amplification, Waters relied on a Fender Tweed Deluxe amp cranked to 50% power, modified with vintage Jensen P12Q speakers that saturated harmonics, giving his slide work on “Hoochie Coochie Man” that signature growl. His tuning: open G (DADGAD), allowing seamless slide between root notes while keeping bottleneck slides fluid. BB King’s gear epitomized “guitar virtuosity + simplicity.” His Lucille—the nickname for his 1949 Gibson ES-175—a thinner-bodied hollowbody with a rosewood fretboard, was his slide instrument of choice, chosen for its even string tension aiding precise bends. He preferred a glass bottleneck slide (1.0″ tall) on heavier strings (custom-gauge .11- .56”) to access the “vibrato-tinged” midrange frequency (800-1200Hz) that defined his phrasing. On amps, he used a Fender Pro Reverb with a Celestion G12H-100 “Greenback” speaker, blending clean tone (40% volume) with moderate distortion via an external Farfisa Compact III organ pedal for “the Thrill Is Gone”’s iconic slide inflections—a secret to layering sustain without overshadowing the slide’s melodic lead. Other legends bring distinct gear configurations: T-Bone Walker innovated with a white Epiphone Zephyr (early set neck) and steel slide (hammer-shaped, 0.3″ thick) for percussive slide accents, often amplifying with a Rickenbacker Combo Amplifier’s 10” speaker for brighter attack. Stevie Ray Vaughan, a modern guardian, used a 1959 Fender Stratocaster with a Danelectro Metal Case Slide (0.200” thickness) and heavy-gauge .13-.58 strings for powerful slide-dive effects in “Pride and Joy.” On tone shaping, Vaughan famously added IBANEZ TS9 Overdrive (Crush setting) before the amp, emphasizing 300Hz bass boost for his slide’s growl. Common equipment threads emerge: metal slides (0.250″ thick bottlenecks) dominate for electric players, while glass (1.0″-1.5” tall) suits acoustic resophonic models. Amplifier wattage remains 50-80% (e.g., tweed Fenders for delta warmth, Fender Pro Reverb for mid-century bloom). Open tunings (EADGBE for standard, open slide G for slide-driven progressions) and custom-gauge strings (over .11) ensure smooth, less-interrupted slides—a bridge between the raw, percussive blues of the twentieth century and the refined, polyphonic art of today’s slide blues.