ClinchFX

What is the EP-PRE

The EP-PRE is a JFET preamplifier that is based on the preamp section of the Echoplex® EP-3® tape echo unit. It will deliver a few db of boost, but I don’t consider it as a boost.

Words such as Enhance, Fatten and Enrich all cover the effect that the EP-PRE has on your tone, but I have yet to find a word that really captures the magic of this amazing little circuit. A friend who has one of the prototypes calls it a “Tone Polisher”.

My own feeling is that it creates a “focus” in my tone and helps me to play with more confidence.

EP-PRE Background

I built my first EP-PRE prototype while recovering from heart surgery in 2007, in response to a thread on “The Gear Page”. A couple of forum members suggested that the preamp section of the Echoplex® EP-3® should be built into a pedal. I took a look at the schematic, and couldn’t really see, at a glance, how such a simple circuit could affect tone, however I was curious and built my version of the preamp. To my surprise, it fattened my tone and sounded great. At this point, I began to seriously analyze the behavior of the circuit, and found that, apart from a small amount of top and bottom cut, the circuit had a non-linear phase response. I believe that this phase response is the secret of the magic tone.

I enjoyed using the prototype and didn’t really consider building the pedal for sale, because my other pedals are my own original designs. Before long, word got out and I began to receive enquiries from guitar players who wanted to buy this pedal. I designed a PCB, and the EP-PRE is now in production.

EP-PRE Features

Volume Control

The Volume control is the equivalent of “Echo Volume” in the tape echo unit, wired in reverse, because there is no echo in the EP-PRE. Because I insisted on keeping the circuit interaction the same as in the original tape echo unit, the Volume control works for only about half of its travel. I considered replacing it with a lower value pot and a fixed resistor, but found that, as you wind it further round, while it doesn’t change the volume, it makes a subtle difference to the tone.

Stomp Switch

We have these switches custom made to our specification, which includes gold contacts for maximum reliability when switching very low current in pedals.

PCB

For best compatibility with either Lead-Tin or Lead-Free solder, the PCB has gold plated pads. The use of SMDs for most of the components keeps the PCB small, and there is a full ground plane on one side of the PCB, to minimise induced noise.

Power Supply

The EP-PRE pedal operates from a 9V DC, Centre Negative power supply that has become the standard for most pedals.

The original EP-3® preamp operates from a zener regulated supply of about 20 Volts DC. The characteristics of the power supply are significant to the operation to the circuit. It just doesn’t work properly on 9 Volts, so the EP-PRE has a Charge-Pump power supply that converts the 9 Volts to more than 17 Volts. A Charge-Pump came closer to recreating the dynamics of the power supply in the EP-3® than I could achieve with an external 18 Volt supply.

The plastic housed DC sockets that are readily available have a very small flange that can be broken if the power cable is accidentally kicked. On all of my pedals, I mount the DC socket on a nylon washer that is cut to an exact fit on the threaded part of the socket. The washer cushions any shock loading and helps protect against breakage of the socket.

Pricing

Pricing for the second build of the EP-PRE is USD $149 plus postage. The continuing variation in relative values of the US Dollar and the Australian Dollar, combined with higher than expected production costs, has made it necessary to increase the price of the second run of EP-PREs by $10.

For anyone who ordered a pedal from the first build and has not yet received it, the price will remain at $139 plus postage.

Sound Clips

I’ve been too busy building pedals to do any recording. Cary Chilton has recorded some clips, and you can listen to them on his SoundClick site here. Cary is a really hot guitar player, and I’m grateful for his enthusiasm and support.

Ordering

The first 50 EP-PREs are now sold, as are most of the second build of another 50 pedals. Early in May, things went a little pear shaped when I began to build some lead-free, RoHS compliant pedals for European orders, and had a major allergic reaction to the flux fumes from the solder. I’m finally back in harness, and the last few pedals in the first build should be ready within the next few days. I should have some second build pedals ready by June 30, maybe before, depending on a component supply problem that came up a few weeks ago.

If you are interested in ordering an EP-PRE, please use the “Contact Us” page to send an email.

® Echoplex and EP-3 are registered trademarks of Dunlop Manufacturing.