Epiphone Blues Custom 30 All Tube Guitar Amp
The Epiphone Blues Custom 30 is a two channel tube amp made for the professional guitarist. It’s been designed by Gibson Labs in Seattle, WA. The amp is a great blues amp but is also a very versatile sounding and capable of more aggressive rock tones. It has both American and British voicings which give it a range of tonal colors: from harmonically rich clean tone to creamy distorted tones to high-gain crunch the amp can do it. It Along with its channel 2 high gain channel with mid-rang control it has two output options for 15/30 watts of power in to two 12 inch speakers.
The two channels are foot switchable with an optional footswitch or you can simple press the button on the front panel. The amp uses 12AX7 (ECC83) tubes in the preamp section as well as to drive the built-in spring reverb. Channel 1 consists of a single volume control. This is the clean channel and is routed to the 3-band EQ which is shared between both channels. When in Pentode mode you can get an aggressive sound by turning this channel up loud but you’ll probably use it for your more clean tone. It sounds very warm and friendly in Triode mode. Channel 2 is the more aggressive channel with its DRIVE and VOLUME controls. It allows you to over drive the preamp stage before it gets to the EQ and power amp. It also has a mid EQ boost that gives the tone more definition and presence. The heater filaments in the preamp tubes are DC rather than AC. AC adds a 60 cycle hum to the signal even though it may only be small amount its done in the right place.
The 3-band EQ is shared between both channels. It has an interesting feature called the “Independent/Interactive” EQ switch. This allows the EQ to behave more like a Fender (Independent) or light a Marshall (Interactive). This may be a too generalized description but its close enough. In interactive mode when you change one of the bands it affects the sound of the other bands. I find the Interactive mode better for me however it’s mainly for tonal variation.
The two power output tubes are 5881 and can operated in either push/pull (A/B) mode at 30 watts RMS or in Class ‘A’ mode at 15 watts. In Pentode mode the amp operates in Class A/B mode which gives it more power as well as distortion at lower volumes. This mode tends to also output more even as well as odd harmonics in comparison to Class ‘A’ operation. When running in Triode mode the tubes are bias to operate in Class ‘A’ mode. This mode is less efficient but outputs more even harmonics at all volumes. Use this mode for a more ‘American’ sound. Use Pentode mode for a more British sound.
The 5881 is really one of the 6L6 variations and is found in many older Fender and Gibson amps. The KT-66 is also one the 6L6 variation that was originally used in the Marshall JTM-45. The term “Ruggedized” means it was made for military use (durability) and mobility. You really don’t want to move your amp around especially while the tubes are hot. The sound of the tube is pretty much the same as the 6L6. They are obviously more expensive than other tubes but the Blue Custom has two of them J
When running in Triode mode the amp is -3dB quieter than when running in Pentode mode. This is mainly because in order to double the actual volume you hear you’ll twice the amount of watts which is exactly what the Triode/Pentode switch located on the back panel of the amp does. The Pentode/Triode switch allows you to decrease the output power of the amp by removing two elements found in the 5881’s output tubes (which are Pentode). This basically makes the 5881 output tube run in triode mode which changes the tonal characteristic of the amp as well as reducing the output power. This is the cheapest way to reduce the output power of an amp without having to remove any tubes (and re-calculating the transformers load requirement which is usually cut in half). The Pentode/Triode switch is the cheapest way to reduce the power. When in triode mode the amp breaks up a little sooner and has a smoother sound with more mids. The high frequency chimey sound is also reduced when in triode mode. For full on tonal crank distortion obviously run it in Pentode mode at full volume. You may also be happy to know that Epiphone added a somewhat quiet fan to keep the tubes cool. This is a nice touch because you don’t have to worry about it getting too hot or putting your own fan back there to keep it cool.
The amp can output to 4, 8, or 16 ohm load speaker cabinets and comes with two 12 inch Eminence Lady Luck speakers. These are 74 watt 16 ohm speakers and have a frequency response of 80 to 5 kHz and are fairly bright sounding. There are two 4 ohm jacks, two 8 ohm jacks, and a single 16 ohm jack on the back panel.
Another great feature is the addition of the 5AR5 tube rectifier. If you’ve ever played through an older Bassman cranked you’ll know the sound. The tube rectifier gives you a compressed sound (dynamically speaking) especially in Triode Mode (Class ‘A’). This is because of what is called “Power Sag” where the 5AR5 can’t supply enough rectified power to the power tubes and a slight drop in output power is heard. It also helps to contribute to a more defined sound. I’m a fan of this type of sound and find it a welcomed addition.