Seymour Duncan Vise Grip Compressor Review – Best Compression Pedal?


Mostly known for their pickups, Seymour Duncan recently released a new line of guitar pedals, including the amazing Vapor Trail Analog Delay, the Tube Screamer-inspired 805 Overdrive, and a revamp of their famous Pickup Booster. I’m glad to see the Santa Barbara based company getting more active in the pedal game again, as they have consistently been manufacturing great pickups for very honest prices for over 3 decades. They’re somewhere in between a big company and a boutique operation, considering they have around 120 employees, and they have been around far too long to benefit from the hype that new companies generally get, so their pedals have perhaps been flying under the radar of many gear-heads. However, their new compressor, the Vise Grip, at first glance seems quite promising, and could be a serious competitor to some of the more expensive compressor pedals out there.


  • Controls for Volume, Blend, Attack, Sustain
  • Compression Ratio: Soft-knee, adjustable from 1:1 to > 20:1
  • Maximum Compressor Gain: +50dB
  • Attack Speed: Adjustable from 2.0ms to 50ms
  • 3 Way toggle switch for selecting dry signal frequency range (mid/full/high)
  • DC input (9-18v) and dedicated battery compartment with ‘easy access door’
  • True Bypass

Seymour-Duncan-Vise-Grip-Compressor-Review-Best-Compression-Pedal-02The build quality is straight forward and solid, on the inside there are three separate circuit boards connected via molex connectors, one for the foot-switch, one for the connectors and another for the pots and toggle switch. It’s clearly not hand built, but I’m a fan of the efficient layout and design. The enclosure, like the rest of their pedal range, is built especially for them, as it’s a little quirky. It’s slightly bigger than usual, it seems like the top side (where the jacks are located) is removable, which I assume makes the pedal easier to assemble, and of course there is that battery compartment with the ‘easy access’ door, which allows for battery changes without removing the backplate.

The glossy finish, a classy dark blue, is maybe somewhat prone to scratching, but mine still shines nicely after a couple of gigs.

Also, considering compressors sometimes aren’t the most straight forward effects to use, compression novices will appreciate the informative user’s guide, which had some very useable suggested settings.

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Sound & Performance

A compressor when used in the conventional way isn’t really so much an ‘effect’, but rather a way of ‘polishing’ your dynamics and sometimes tone, making them more manageable and pro sounding while preserving the character of your guitar, and any time you clearly detect the signal being compressed you are probably using too much.

Most of the time I started off with one of the suggested settings, slowly tweaking as I went along, and as recommended in the user’s guide, I generally used it as the first pedal in my chain (unless there was a vintage style fuzz or envelope pedal involved). I also unfortunately did not have to the opportunity to try it in the effects loop of an amp, which is another useful placement, and this might be where the 18v operation can come in handy. Effects loop signals can be hotter than normal, so the Vise Grip might benefit from the added headroom here since I did notice some clipping when feeding it a heavily boosted signal.

Seymour-Duncan-Vise-Grip-Compressor-Review-Best-Compression-Pedal-03The first thing I noticed when playing around with it was that I was able to dial in just the right amount of compression with the extremely useable ‘Blend’ control. This allowed me to keep the guitar sounding natural by blending in the unaffected ‘dry’ signal, a studio technique otherwise known as ‘parallel compression’. Important to note is that this control works somewhat counterintuitively from most compression pedals. When turned all the way down only the compressed signal is heard; when at maximum only the dry signal is.

The ‘Attack’ control adjusts how quickly the compressor reacts to the notes and allowed me to keep my picking dynamics intact, or get rid of them altogether for a more consistent volume level. At extreme settings, with the sustain on high and the attack low, the Vise Grip can create a heavy ‘pump/suck’ sound, which is way over the top for a lot of playing styles but certainly does have its uses, mainly when doing more ambient/swell type stuff where the attack is removed altogether. The Vise Grip did a great job in this regard, especially in combination with some delay and light modulation.

When using the compressor as an ‘always on’ effect I also generally set the level control to boost the signal, which also seemed to somewhat even out the overdrives further down the signal chain. When dialing in a more distorted sound (using either pedals or amp drive) for lead stuff, setting the Sustain to maximum would let notes go on for as long as desired while enhancing feedback and harmonics. It’s worth noting that placing a compressor before or after any drive effects will yield different results, especially when using it as a volume boost, and some experimenting is definitely advised.

One of the biggest issues regarding compressors is their ‘transparency’, or how much they color your tone, since in a perfect world only the dynamics would be affected, and not the harmonic content, but the Vise Grip performs surprisingly well in this department which is no doubt due to it being of the studio-grade VCA variety as opposed to the OTA type (à la Ross, Dyna Comp, etc).

If you are looking for some tonal changes however, using the toggle switch to compress only a certain frequency range can have quite an interesting effect. Although I generally preferred it set to ‘Full’ (i.e. neutral), the switch is capable of changing the character of your sound quite a bit, focussing on the top end or mids while leaving your bass notes intact. Keep in mind that this switch does not have any affect if no dry signal is blended in as it only affects the uncompressed signal. It’s clearly voiced for guitar, especially considering Seymour Duncan also released a dedicated bass compressor which I suspect is a tweaked version of the same circuit. And understandably, on the ‘Studio Bass’ compressor, as they named it, the ‘High’ setting has been replaced by a ‘Low’ toggle setting.

Like all compressors, depending on how it’s set, it also tends to bring out the noise in your signal, and although I didn’t feel like it adds much noise by itself, with single coils and some overdrive this can be a reason to not crank the sustain too far. And while there are much fancier and more flexible studio-grade compressors out there, those pedals are often at least double the price and footprint and are probably overkill for most pedalboards.

Seymour-Duncan-Vise-Grip-Compressor-Review-Best-Compression-Pedal-04Having gigged with it for a while, I really like the solid overall feel of the Vise Grip. The fact that it’s quite chunky allows for clear labeling and plenty of space between the knobs, making adjustments in a live situation a breeze. The only thing I’m somewhat skeptical about is the ‘easy access’ battery door; being plastic, I’m not sure how it will hold up over time with regular battery changes. On the other hand, I’m often times somewhat worried about batteries being able to move around freely in the same space as the circuit board and wiring, so having a separate compartment definitely solves that.



The Seymour Duncan Vise Grip offers good value, great sounds, and plenty of flexibility for a straight forward guitar compressor without unnecessary frills. Stylistically, it’s quite versatile as well, thanks to its controls and Mid/High/Full tone switch, and I could see it working well in a variety of different genres. It might not qualify as ’boutique’ and definitely has more of a mass produced feel to it, but Seymour Duncan certainly had their priorities straight when designing this workhorse compression pedal. While some guitarists may never need a compressor, I do think the Vise Grip would be a great buy for the type of guitarist who is going for a slightly more elaborate setup than the basic drive/modulation/delay pedalboard. I have to say I’m enthusiastic about Seymour Duncan’s complete pedal line-up, and the Vise Grip is no different. I’m definitely a fan.

That concludes our Seymour Duncan Vise Grip Compressor review. Thanks for reading.


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Keeley Electronics C4 4-Knob Compressor Review – Best Compression Pedal?


Reviewing the Keeley Electronics “4-Knob” Compressor almost seems redundant. After all, this is the pedal that put Keeley Electronics on the map and helped make Robert Keeley one of the most respected names in the boutique pedal industry. There’s no question as to whether the 4-Knob Compressor is a good pedal. It’s a certified classic in the realm of boutique guitar pedals. But with new pedal builders practically coming out of the woodwork and countless compression pedals released since Keeley’s classic “2-Knob” version came on the scene, it’s Best Guitar Effects’ continuing mission to discern which pedals remain at the top of the pecking order. Does the classic 4-Knob Compressor still hold up today? Is it the best guitar compression pedal around? We’ll help you answer that in our Keeley Electronics 4-Knob Compressor review.

Here’s a quick feature rundown before we jump right in with this one.


  • Controls for Sustain, Level, Clipping & Attack
  • Tone-tested components
  • True bypass switching circuit
  • Triple-pole double-throw switch
  • Powered by 9-volt battery or 9VDC power adapter (current draw: 5mA)

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Sound & Performance:

The Keeley C4 4-Knob Compressor is designed to do two things: compress your guitar signal and provide smooth sustain. It does that with four easy-to-use controls: Sustain, Level, Attack, & Clipping. The old 2-Knob Compressor (now discontinued) had the Attack & Clipping controls inside the pedal. The 4-Knob version, or “C4” as it’s now called, puts these essential controls on the outside as they’re quite useful for configuring the pedal to your current guitar and style of playing.

The Sustain and Level controls will be familiar to anyone who’s ever used or at least heard of the old Ross Compressor or Dyna Comp. The Sustain control essentially increases the amount of compression (ratio) and puts more of a squeeze on your guitar signal as you crank up the knob. The Level control sets your overall volume level. Easy enough.

Keeley-Electronics-C4-4-Knob-Compressor-Review-Best-Guitar-Compression-Pedal-02The Clipping and Attack controls are where things get interesting. The Clipping control limits the input signal going into the pedal before it hits the Sustain section. Think of it as a sort of pre-gain control. For lower level signals you may want to increase the setting or max it out. If you’re running a hotter signal or noticing additional noise or distortion, cut it back a bit. While the manual generally recommends leaving it all the way up, I find myself sometimes liking to pull it back a bit to decrease the amount of saturation produced from higher Sustain settings. What’s really interesting is how higher Clipping settings can liven up your tone and impart a very unique character on your overall sound. It adds to the vibe of the 4-Knob Compressor and contributes to why so many people love this pedal. The Keeley C4 Compressor has its own unique vibe and sound, a quality shared by the most famous studio compressors.

The Attack control adjusts the recovery time of the compressor, seeming almost more like a “release” control. Attack and release seem like both sides of the same coin here. A higher Attack setting gives your guitar a quicker, punchier sound, while lower settings make the sound “bloom” after your initial pick attack. The lower Attack settings are more useful for light chordal work and slower, fragmented playing for sounds that are lush and beautiful. The higher settings are preferable for quick, single note playing and when you’re using the pedal for singing solos that sustain at consistent volume levels.

And that’s part of what makes the 4-Knob Compressor so versatile. Whether you’re playing clean chords, dialing it in for searing leads, getting your funk on, or going for some country twang, there’s a setting here that’ll get the job done. This pedal is also the first stompbox I ever discovered was being used by studio engineers on a variety of instruments and audio signals. The Clipping knob comes into play here for handling higher line levels.

While Keeley Electronics have since released the GC-2 limiting Amplifier & Keeley Compressor Pro pedals, the classic 4-knobber is still going strong and stands out among other similarly Ross-inspired guitar compressors. I always look forward to seeing older designs reimagined. I’m one of those few guitarists that always think the best is still yet to come. But the 4-Knob Compressor got something right, and few pedals can even come close to the quality that Robert Keeley cooked up with this pedal.

The Keeley Electronics 4-Knob Compressor has still got it after all these years. It’s still up there with the best guitar compressor pedals. Let’s see the final result.



The Keeley Electronics C4 4-Knob Compressor lives up to its reputation and is still one of the best guitar compression pedals available today. While inspired by some classic compressors, Keeley’s pedal has become just as much a legend in its own right. Whether you want subtle compression or heavier squashing of your signal, the 4-Knob Compressor always remains musical while adding a pleasing sustain to your guitar. And it has a unique tone of its own among stompbox compressors. Nothing around sounds quite like it. And fewer pedals still can compete with this level of sheer overall quality.

That concludes our Keeley Electronics C4 4-Knob Compressor review. Thanks for reading.


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Pigtronix Philosopher’s Tone Germanium Gold LTD Review – Best Compressor?


For ancient alchemists, attaining the legendary Philosopher’s Stone was the result of a lifetime of dedication to the Great Work. Many of them did not succeed. But the engineering wizards at Pigtronix have turned lead to gold once again. Behold the Pigtronix Philosopher’s Tone Germanium Gold LTD. For those who already regard the original Philosopher’s Tone as one of the best guitar compressors available, this limited edition variation of that classic pedal may be your new holy grail.

As Above, So Below

The Philosopher’s Tone Germanium Gold LTD uses 1N60 Germanium Diodes in an asymmetrical clipping format. This results in a very smooth top end and midrange response, resulting in even more character and punch than the original Pigtronix Philosopher’s Tone. The differences in these two guitar pedals become apparent when you compare the sound of the grit settings on offer. More on that in a moment. Let’s run down the features and dive into our Pigtronix Philosopher’s Tone Germanium Gold LTD review.


Germanium Enhanced GRIT.


Handpainted by Jason Myrold in a Gold Sparkle Finish.

Limited Edition.

Exclusive for ProGuitarShop.

Grit control mixes in a smooth layer of distortion into the effect.

Sustain control sets the threshold for the compressor. Turn it up for more intense compression and sustain.


Blend control determines the mix of effected and dry signal.

Treble control buts or boosts frequencies at 2k.

Volume control sets the overall output level of the device when engaged.

Super compact form factor.

No noise operation.

Powered by included 18VDC 300ma negative tip power supply.

Visit Pigtronix for more info about the Philosopher’s Tone Germanium Gold LTD.

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Sound & Performance:

Be sure to check out my Pigtronix Philosopher’s Tone Review for comparison. I tested and reviewed both at the same time.

The Pigtronix Philosopher’s Tone Germanium Gold LTD is very similar in most regards to the original Philosopher’s Tone with the exception being the different tonal character provided by the Germanium Diodes.

Using an American Stratocaster and a clean amp sound, I was pleased to find that the Germanium Gold LTD is just as pristine and quiet when using it at flat knob settings.

I did a lot of A/B comparisons between the two pedals. The Philosopher’s Tone Germanium Gold LTD does have a little more power than the original Philosopher’s Tone at extreme settings. With no Grit and the Volume maxed out with the other knobs at noon, the Philosopher’s Tone Germanium Gold LTD punches through with a bit more authority.

The tone of the Pigtronix Philosopher’s Tone Germanium Gold LTD just seems a bit more colorful than the original Philosopher’s Tone which sounds a little more dry by comparison. The variation in tone between the two Philosopher’s Tone pedals is so subtle that it’s difficult to say one sounds better than the other. It’s simply a matter of personal taste that warrants close listening from ears experienced enough to hear the subtle differences.

The Philosopher’s Tone Germanium Gold LTD packs in the same level of versatility as the original Philosopher’s Tone, making it ideal for any compression need whether it’s country twang, warm jazz, bright funk, or saturated lead tones. Like the original, this pedal does it all and does everything exceptionally well.

Turning the Grit knob allows the differences of these pedals to become more apparent. I find the Germanium flavor of the Grit to be a bit thicker and a little fuzzier. The original Grit is a little more transparent in nature. The Germanium grit of the Philosopher’s Tone Germanium Gold LTD is just as adept at enhancing your drive sounds when used in front a distortion pedal or overdriven amp.

While the original Philosopher’s Tone specializes in really preserving the character of your guitar on every setting, the Philosopher’s Tone Germanium Gold LTD infuses your tone with the added character of the Germanium Diodes when blending in the Grit. This is a very welcome addition for anyone who appreciates that sought after character afforded by quality Germanium Diodes. For those who appreciate the Germanium flavor, you’ll certainly feel that Pigtronix have taken a good thing and made it even better. P.S. Try this pedal in front of the Pigtronix Mothership guitar synth pedal for a more consistent signal and epic guitar synth tones.

Let’s have the final result.



The original Pigtronix Philosopher’s Tone is a modern legend in it’s own right. The new Philosopher’s Tone Germanium Gold LTD adds a welcome chapter to that legacy. This is a truly versatile compression pedal that will turn any sound to gold. The Germanium Diodes add a unique character that makes this pedal a great alternative to the already amazing Philosopher’s Tone. If you’re looking for the best guitar compressor out there, be sure to try out the Pigtronix Philosopher’s Tone Germanium Gold LTD. It may be the final alchemical stage to perfecting your ultimate guitar tone.

That concludes our Pigtronix Philosopher’s Tone Germanium Gold LTD review. Thanks for reading.


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Xotic SP Compressor Review – Best Guitar Compression Pedal?


There are many guitar compression pedals available on the market, several of which seek to emulate and surpass the famed Ross Compressor. Xotic decided to have a go at creating a compressor in the vein of that classic pedal while adding more versatility and sound-shaping options than most pedal makers have ever packed into such a small enclosure. Is this the best guitar compression pedal out there? Our Xotic SP Compressor review will help you decide if this is the compression pedal you’re looking for.



Uses the same OTA (operational transconductance amplifier) technology use in the famed Ross Compressor.

Tones ranging from vintage, to subtle, to modern, and more.

Volume knob for up to +15db of boost.

Blend knob for finding the perfect balance between the dry and compressed signal.

2 Attack/Release internal dip switches.

High Cut Filter internal dip switch for controlling high frequency roll off capacitor (220pf).

Input Pad internal dip switch for preventing distortion and low cut filter control.

True bypass for eliminating any signal interference when switched off.

Powered by 9-volt batter or 9VDC power adapter. May also be run at 18-volts with the Xotic Voltage Doubler.

Visit Xotic for more info about the Xotic SP Compressor.

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Sound & Performance:

I had a feeling this was going to be a really interesting pedal right when I pulled it out of the box. The Xotic SP Compressor has a real simple, yet sleek look, similar to the Xotic EP Booster and Xotic SL Drive pedals. It’s also surprisingly heavy for such a tiny little pedal. You instantly get the feeling that Xotic built a real solid and durable pedal. This isn’t some low-budget knock-off pedal.

Having a glance at the included manual reveals that this pedal contains 4 internal two-way dip switches in addition to the 2 surface knobs and three-way Lo/Mid/Hi toggle switch for a total of 7 parameter adjustment controls. That’s a lot of options for such a small unit. You can really tell that Xotic spared no consideration for offering the most versatility they could squeeze into the SP Compressor.

I went ahead and unscrewed the bottom of the enclosure to allow instant access to shaping my tone while testing this pedal for my review. I recommend doing the same when you un-box your SP Compressor to spend some time finding your preferred settings. Although, it does sound pretty great in it’s default settings. You may just want to leave it as is.

Xotic-SP-Compressor-Review-Best-Guitar-Compression-Pedal-03I started with a single-coil Strat sound with a clean amp and the SP Compressor in between. With the knobs on the pedal at noon and the Sustain/Compression toggle switch set to Lo, I activated the effect and was greeted to a nice boost in volume.

At this setting the compression is quite subtle, but there is a slight increase in sustain. Tweaking the Volume and Blend knobs in the range of 10 to 2 o’clock helps to find a good amount of blended compression level. The effect is smooth and pleasing to the ears, and this is a great starter setting for adding just a bit of clarity and boost to your clean phrasing.

Things get a bit more interesting by flipping the Sustain/Compression switch to the Mid position. With the internal dip switches at their default position this puts you in what the SP Compressor manual labels as a Classic Vintage style compression. I find this setting to be a great all-around compression sound for most applications.

Again, just a slight tweak of the Blend knob really lets you dial in the compression just the way you like it. The Blend knob really is the most ingenious function on this pedal and really sets the Xotic SP Compressor apart in a crowded market. This pedal really is something special and is surely to become a secret weapon of many guitarists. Did I mention the pure, near-transparent tone? For an OTA style comp it’s not as overly colored as some lesser compressor guitar pedals.

Flipping the internal Attack/Release dip switches to the On position for quicker attack and release times brings in the twang if country-style compression is what you’re after. Flip the High Cut filter dip switch from its default position if you want to make your sound even brighter. Watch out though. This pedal really cuts though. The SP Compressor never ceases to amaze me with how much control it offers for crafting your ideal compression sound.

The SP Compressor works exceptionally well for really making your lead sounds cut through with singing sustain. Try it with a humbucker equipped guitar for some really fat sounds. Flipping the Compression/Sustain switch to Hi may raise the noise level a bit too much for most clean applications, but it may just be perfect for your gain-saturated guitar solos. No matter what your compression needs may be, there is a setting to be found in this pedal that will get the job done.

If you’re a session player who travels light when it comes to effects, you may appreciate that this pedal is so tiny while still offering 9-volt battery power. Huge tonal options, minuscule size, and plug-and-play convenience. The SP Compressor is hard to beat in every category.

UPDATE: I had the opportunity to try the Xotic SP Compressor with the Xotic Voltage Doubler (as seen in the video above). This allows you to achieve even more headroom from the pedal. It’s definitely worth trying as it provides a subtle sonic upgrade to what is already a great sounding compressor. The difference isn’t night and day, but it’s certainly noticeable and may offer a sound that you like even more. You can also use the Xotic Voltage Doubler with the Xotic EP Booster and SL Drive (and other 18-volt compatible pedals), making it a useful accessory to have indeed.

Let’s have the final result.



Xotic really went all out with the SP Compressor. This pedal offers more versatility than most compressors out there while remaining small enough to find a home on any crowded pedalboard. Whether playing sparkly cleans or distorted leads, the SP Compressor will bring your tones to life with unrivaled clarity. The SP Compressor has positioned itself in the top tier of the battle for best guitar compression pedal on the market. This may just be the only compressor you ever need. I’ll be spending a lot more time with this pedal myself. I suggest you get acquainted with it, also.

That concludes our Xotic SP Compressor review. Thanks for reading.


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