Eden Glowplug Bass Tube Warmer Pedal

Eden Glowplug Bass Tube Warmer Pedal

Can it give a solid state amp a warm tube glow?

By Phil O'Keefe

Bassists have embraced solid state amps far more than their guitar-playing bandmates. In the past decade or so there has been a big increase in the popularity of high-power but very lightweight Class D heads. All of this is great in terms of power, projection and ease of transportation, but many players miss that tube-seared tonal bliss.

Well, Eden thinks they have a solution that will benefit many players with solid state amps - why not put a tube in a pedal that you can run with your solid state amp? Wouldn't doing so bring some tube warmth to an otherwise all-solid-state rig? That's exactly what their new Glowplug Bass Tube Warmer pedal is all about.

What You Need To Know

• The Eden Glowplug gives solid-state bass amplifiers some of that characteristic tube warmth, growl and coloration. It's not a typical distortion or fuzz pedal, but uses saturation from a real 12AX7 preamp tube to give your low end some serious warmth.  

   

• The tube at the heart of the Glowplug is built into a heavy duty folded steel enclosure measuring 2.4" H x 5.7" W x 3.5" D. The front of the pedal is angled, which somewhat helps to keep your foot away from the pedal's knobs.

   

• Speaking of knobs, the Glowplug features some really cool looking black chromed knobs with red stripe indicators that are not super easy to see, but I have to admit that white stripes wouldn't look as cool. Many users will probably treat this as a "set it and forget it" type pedal, so it's not really a deal-breaker.  

   

• The Eden Glowplug is powered by an included 15V DC power adapter. Powering the pedal with a battery is not an option. A 2.1mm center-positive socket is located on the rear of the pedal, which also proudly displays the Eden name in large letters.

The controls on the Glowplug are very simple to understand, but provide plenty of capabilities for the pedal's intended use. There are four knobs:

• Warmth: Labeled from Cool to Hot (full-up), this knob adjusts the amount of tube warmth and saturation. The goes from subtle coloration to a smooth growl, but with most basses never gets to fuzz or distortion pedal territory.

   

• Crossover: This adjusts the pedal's built-in crossover from 100 Hz to 1.3 kHz. Frequencies below the crossover point will be affected by the Glowplug's tube warming circuitry, giving you a warmer and fuller-sounding low end while higher up, the highs remain undistorted and detailed.

   

• Mix: This adjusts the ratio of processed and unprocessed signal, from 0% processed to 100% processed when it's dimed. I found setting this knob full-up was helpful when dialing in the Crossover and Warmth controls, and then I dialed Mix back to where the sound had the desired amount of coloration.   

   

• Volume: Sets the Glowplug's overall output level. Unity gain is about 10 or 11 o'clock on the knob, depending on where you have everything else set. You can go way beyond unity gain with this control, so it's possible to use the Glowplug as a boost too.  

   

• The expected 1/4" input and output jacks mount on the right and left sides of the pedal, respectively.

• Switching is buffered bypass and a bright red LED right next to the switch illuminates when the Glowplug is active. There's also a second red LED located at the top of the pedal, just to the right of the Eden logo, that indicates when power is on.

   

• The entire bottom surface of the pedal is lined with a thin sheet of rubberized foam material that gives the pedal a good grip on the floor and helps to keep it from sliding when you step on it.

Limitations

• Eden states that there are no user serviceable parts inside, and that attempting to open the pedal will void your warranty. The good news is that the Glowplug's "starved plate" design means the tube is never driven at high voltage and so it should last indefinitely.  Here's a "gut shot" to satisfy your curiosity.

   

• While the angled front does help you hit the pedal's footswitch, the location of the knobs near to the front of the pedal means there is still the potential to accidentally hit them with your foot. Take care when switching the pedal on and off to avoid possibly damaging one of the controls.

   

• A word of caution about powering the Glowplug: The pedal uses a center-positive wiring configuration rather than the far more common center-negative configuration, so you can't use it on a power daisy chain with other pedals, and won't be able to use it with your brick-style pedalboard power supply (unless it has an isolated 15V DC output). The included 15V DC 400 mA power supply should not be used with other pedals since it has a higher-than-usual voltage, and a center-positive wiring configuration that may damage them.

Conclusions

The external build quality of the Eden Glowplug is excellent, with a beefy feel and solid, cool-looking knobs that exhibit nary a trace of wobble or flimsiness. Good thing too, since the placement of the pedal's knobs means they're probably going to take the occasional kick from your foot unless you're careful.

As far as sound, can the Glowplug really turn your solid state bass amp into a fire-breathing tube monster? Not really - with only one tube it can't give you the same coloration you'd get from an all-tube amplifier's preamp and power amp tubes, but it does exactly what Eden claim in the product's name: give your powerful but overly clean solid state bass rig some extra warmth and tube coloration. To that end, the Crossover function really surprised me. Initially I expected it to act like some bass distortion pedals that let you process the highs and mids above the crossover frequency while leaving the lows alone so you don't mess up the all-important fundamental, but it essentially works in the opposite way. I expected this to lead to lack of focus in the lows, but even at fairly high Mix and Warmth settings, it gave my bass tone a bigger, fuller and subjectively "better" sound without getting flabby or farting out.

When the crossover is turned up higher you can also affect the mid frequencies. This gives more obviously "distorted" sounds, but they always remain fairly smooth and not too heavy - if you're looking for a dedicated bass fuzz, then you'll probably want to look elsewhere. Where the Glowplug shines is in warming up the sound of your solid-state bass amp and giving your low frequencies a more tube-like glow. It's very easy to use and remarkably effective, so if you rig needs more girth and glow, go give this a go. 

Resources

Eden Glowplug Bass Tube Warmer pedal ($240.00 MSRP, $199.99 "street")

Eden's product web page (which also includes sound clips)    

Eden Glowplug quick start guide (PDF file)  

You can purchase the Eden Glowplug Bass Tube Warmer pedal from:

B&H Photo Video

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Phil O'Keefe is a multi-instrumentalist, recording engineer / producer and the Senior Editor of Harmony Central. He has engineered, produced and performed on countless recording sessions in a diverse range of styles, with artists such as Alien Ant Farm, Jules Day, Voodoo Glow Skulls, John McGill, Michael Knott and Alexa's Wish. He is a former featured monthly columnist for EQ magazine, and his articles and product reviews have also appeared in Keyboard, Electronic Musician and Guitar Player magazines.