Electro-Harmonix Hot Tubes Nano Overdrive

The return of the legendary 70s-era CMOS overdrive

By Phil O'Keefe

Vintage effects can be a funny thing. It's nearly impossible to tell you today which of the currently-available crop of effects will become highly-sought collector's items that will be prized by players thirty-five years from now. One pedal from the 1970s that has become very in-demand with modern players is the original Electro-Harmonix Hot Tubes Overdrive. Originally introduced back in 1978, this vintage pedal has enjoyed continued popularity that has only grown in recent years, and which has sent the prices for used examples soaring - often exceeding $300 for an original in working condition.

Because of continued requests by players, Electro-Harmonix has decided to reissue this classic design. While the circuit itself remains basically unchanged, there are a few minor differences between the vintage originals and the new Nano versions. The question is, did they change the sound?

What You Need To Know

• Based on the original EHX Hot Tubes pedal from 1978, the Hot Tubes Nano utilizes the exact same circuit as the vintage pedal, but it is now constructed primarily with surface mounted components and housed in a much smaller die-cast aluminum enclosure. Like the other pedals in the EHX Nano lineup, the new pedal measures 4 5/16" L x 2 1/2" W x 2" H, including the knobs, switch and jacks.

• Like the original, the Hot Tubes Nano Overdrive is made in the USA.

• The circuit is based around a CMOS (complementary metal-oxide semiconductor) FET chip, just like the original. These chips tend to be very low-noise and have low power consumption, both of which make them well-suited for use in guitar pedals.

• The Input and output (labeled "Amp") jacks are mounted on the sides of the pedal. The input impedance is 100kOhm. The output impedance is dependent on the position of the Volume knob, and varies from 350 Ohm to 3kOhm. In one of the few changes from the original pedal, there is no Direct Output jack.

• The Hot Tubes Nano can be powered either by a 9V battery (one is pre-installed in the pedal from the factory, and can be accessed by removing the four screws that hold the pedal's bottom plate in place), or an optional 9V DC power adapter with a minimum of 50mA of current (not included). The power jack is located at the top of the pedal, accepts the industry-standard 2.1mm barrel style plugs, and is wired center-negative. Current draw of the Hot Tubes Nano Overdrive is 18mA at 9V DC. Removing the plug from the input jack disconnects the battery, so to help extend its life when relying on battery power, always disconnect the input cable whenever you're not using the pedal.

• The controls on the Hot Tube Nano are very straightforward. A knob labeled Overdrive controls the amount of distortion and grit, while a Volume knob adjusts the pedal's overall output level. A Tone control rounds out the knobs, and allows players to adjust the tonal shading to their preferences. The Hot Tubes Nano Overdrive also includes a small two position top-mounted toggle switch that allows you to bypass the Tone control entirely. When bypassed, the tone stack is completely out of the circuit, and the tone gets a bit darker, and the overall output level of the pedal is slightly increased. 

• There's quite a bit of range available in terms of the amount of overdrive, from light and subtle at lower Overdrive knob settings (below 12 o'clock), to quite distorted when turned up higher. The overdrive's tonal character leans towards bright and raspy, although the brightness can be tamed with the Tone control if desired. The pedal responds well to variations in the player's touch, as well as to guitar volume control adjustments. Similarly, there is considerable range available from the Volume knob too, and it's very easy to get a significant boost above unity gain with this pedal.

• The Hot Tubes Nano overdrive features true-bypass switching. A red LED next to the switch illuminates when the pedal is active. There are no additional switches or trim pots inside, so the only reason to open it up is for changing the battery. If you use an AC adapter, remove the EHX-branded internal battery (complete with photo of EHX founder Mike Matthews) that comes pre-installed from the factory, and you'll never need to open it up again.

Limitations

• The surface mount construction means that modifications to this pedal would be difficult to impossible for most people to perform. However, since the circuit is the same as the coveted original, and with the addition of the true-bypass footswitch to the Hot Tubes Nano version, modifications are probably not going to be a major concern for most users.

• While the sound of overdrive pedals is extremely subjective, there are really no other major concerns or limitations with this pedal. Sure, it's not really capable of creating gobs of thick fuzz, but if that's what you seek, you should be looking to something like the EHX Big Muff Pi instead of at an overdrive pedal. That's not to imply that this pedal is whimpy - The Hot Tubes Nano can certainly produce some pretty heavily overdriven tones, as well as more subtle amounts of drive.

Conclusions

What can I say? It looks like we have yet another winner from EHX. While I didn't have access to a vintage Hot Tubes in order to do a side-by-side comparison, the sound of the new Hot Tubes Nano is identical to my recollections of the original units. You can get a lot of drive out of it, but it still cleans up well when you lower your guitar's volume or ease up on your picking attack strength. It's definitely something different than a TS-style overdrive in terms of tones, and players who are looking for something a bit out of the ordinary will certainly find it here. 

Electro-Harmonix has really been upping their game lately when it comes to overdrive and distortion pedals, having recently released several new models that really shine. The Hot Tubes Nano Overdrive is yet another example of that. What's more, the pricing on these pedals is almost unbelievably low, and it's possible to purchase a new nano-sized Hot Tube OD, plus a couple of additional new EHX drive pedals for less than a vintage original Hot Tubes would cost. You get the exact same circuit as the original Hot Tubes, along with a more robust and pedalboard-friendly enclosure. In fact, you could fit three nano-sized pedals into the space that a single original Hot Tubes Overdrive occupied, with room to spare. The same sound and features in less space, and for less money? Yes please!

For fans of the original, the nano version of the Hot Tubes Overdrive is a must-have; you can now get the same sound live and leave your expensive vintage unit at home or in your studio. For people unfamiliar with the original, it's a cool flavor that's not quite like any other overdrive, and it is well worth checking out if you have the opportunity. Kudos to EHX for continuing to offer great pedals like this at such affordable prices.

Resources

Musician's Friend EHX Hot Tubes Nano Overdrive online catalog page ($77.75 MSRP, $58.35 "street")

Electro-Harmonix Hot Tubes Nano Overdrive product web page

EHX Flashback page covering the original 1978 Electro-Harmonix Hot Tubes Overdrive pedal

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.