The Gamma Ray Tube Vocal Preamplifier with Spring Reverb, Delay and Tremolo






Built for Gemma Ray

Gemma Ray's Gamma Ray Vocal Preamplifier is one of my favorite projects to date.  The idea was to build a device that Gemma could use on stage to not only enhance but to effect the vocal signal live.  Therefore, we decided on a spring reverb, tremolo, and a delay built in parallel to the preamplifier.  These can all be turned off and on with an external foot switcher box.  All four signals are mixed together and and sent through a balanced output to the front of house mixing desk.  

As the original Siemens test equipment used a plethora of EF95 and EF94 tubes, I decided to stick with these as the base for the circuitry.  The EF95 makes for an excellent triode and the EF94 in pentode mode delivers enough current to drive the spring reverb.  The microphone preamplifier consists of a two stage circuit with a gain and high pass filter as well as an output level which allows for more control-- anything from a growly distortion to extremely clean is possible.

The case is robust and built to last.  With an excellent leather handle and large front grips, it is easy to carry and makes a nice impression.

The White Chocolate Super Filter / Auto-Wah Wah






Built for Yavor Yordanov

Hot on the heels of the Hot Chocolate Filter and Auto-Wah comes the newest incarnation-- the White Chocolate Super Filter / Auto-Wah Wah.  Yavor contacted Rerun about making a pedal similar to that of the Hot Chocolate Filter after seeing Tim Gane with Cavern of Anti-Matter playing live.  For Yarov's model we changed a few elements but kept the same basic shape and circuit.  

The first thing we both agreed on was that having an input level control could be handy.  This allows the user to adjust how fast the envelope attack comes as well as offering the chance to overdrive the filter.  The filter itself is the same State Variable filter used in countless synths and so on but offers the control of Low Pass, Band Pass and High Pass concurrently.  Even without the envelope control, this filter is extremely flexible and can make some extreme sounds from chocolate thick to eye-watering harsh!  

When the envelope section is brought in, the signal is typically compressed and makes for loads of fun playing off the crazy duck and bwahhh tones.  By mixing in the various filters, one can have more or less of the original signal.  As the unit uses a bipolar power supply, headroom is no problem for most instruments and line-level signals, it sounds great on bass and guitar but also drum machines and clavinets.  






The Diatherapuncteur 6 Channel Tube Mixer with Spring Reverb and EQ






Built for Larry Mullins

The Diatherapuncteur Tube Mixer is a 6 channel unit with built-in spring reverb, "tilt" equalizer, headphone amplifier as well as separate outputs for the mix (transformer balanced), monitor, reverb, and channel direct-outs.  The idea for this unit came about as Larry was looking for a stage mixer to go on tour with Nick Cave.  He is playing keyboards and effects therefore a line level mixer was needed-- channels 1 and 2 offer a slightly higher gain and can accept guitars as well.  

The circuit is relatively simple with a regulated power supply and ECC82s providing the channel gain.  The signal is then led into a passive "tilt" EQ to adjust the frequencies.  This allows for a smooth, but dramatic if needed, change of the original character.  The signals are then mixed together with the reverb return (or this signal can be sent separately to the FOH) and amplified again by the driver circuit to allow for a transformer balanced output.  As this is primarily a stage mixer, the headphone output was taken before the master so that it is entirely independent, thereby making headphone listening a bit easier on the stage.  

The case comes from the same Diatherapuncteur model as the previous equalizer I made, this time inverted for table top use.  All the internal structure and front and back panels were built separately.

The Messgenerator Tube Bass Amplifier





Built for Elli Fugmann

The Messgenerator bass amp is another example where the case suits the end result perfectly.  Because it is big enough, the case could accept large transformers, tubes and the main filter capacitors which are of polypropylene.  They will last a lifetime and are very effective.  There is no hum, the amp is absolutely silent.

I did take some liberties in this amp to add transistors where they would improve the reliability or tone of the amp.  That means there is an "electronic choke" to improve filtering.  As well, the KT88 output tubes are direct coupled with source follower inputs to allow for less blocking distortion which is always a big problem with bass amps due to the large coupling capacitors.

The amp sports a pretty classic circuit with a triode input feeding a pentode and direct coupled cathode follower.  From there is a James tone stack with treble, mid and low controls.  The triode section can also switch between three different bass eq settings-- thin, thick and obese!  Naturally, the normal optical compressor is also included.

The unique touch however is a suggestion from Elli.  She wanted to have a built-in fuzz sound that could be controlled by a footswitch.  It's a cool idea because it allows the amp to mix the original signal with the fuzz so there is never the problem of a weak, thin fuzz sound.

The Piano 88 Dual Tube Microphone Preamplifier







Built for Ed Carlsen

The latest microphone preamplifier from Rerun comes from a request from Ed Carlsen to create a unit that will respond well while recording piano.  Most of the time condenser microphones are used to record piano in the studio.  This means that a dedicated preamplifier doesn't need a lot of gain but does need to be very low noise and not prone to distortion.  For this preamp I set a goal of around 45dB of gain and tried to keep things as simple as possible.  Due to the restrictions, a transistor-regulated power supply was a must which does add a certain amount of complication; however the benefits of doing so outweigh any hesitations.  

The name come from the fact that I used two different "88" tubes-- the ECC88 as output driver and an ECC808 as gain stage.  Of course the fact the piano has 88 keys is just a happy accident!





The Stingray DRT 25 Watt Reverb & Tremolo Combo





Built For Nick Berry

The Stingray is the latest Rerun amplifier.  It is in a combo format with an output of 25 Watts.  It also includes Tremolo and Reverb functions as well as the normal Mids and Tone frequency controls.  Nick was specifically looking for an amp to pair with his Nick Page Les Paul style guitar.  As the guitar had a wide variety of sounds, he needed an amplifier that could reproduce them effectively.  

The main goal with this amp was to produce a warm, compressed tone.  For this reason, I chose to use a pair of 5881 output tubes in cathode bias.  With enough voltage and the proper output transformer ratio, this circuit can produce wonderful clean tones as well as smooth dirty sounds with ease.  The rest of the circuit is also very simple with a pentode front end and a paraphase inverter.

The lovely bespoke knobs and controls were produced here in Berlin by Bremio Instruments who also work with Nick Page Guitars.  


The Rectifa Power Supply Unit & Magnetic Sound Preamplifier





Built for Doug Henderson of micro-moose-berlin

This project came out of the fact that Doug had a full set of the General Precision Laboratories preamplifiers as well as the enclosure to go with them.  These preamplifiers were designed to amplify the signals from cinema projectors and as such had an enormous amount of gain as well as noise-- simply too much for a typical studio environment.

Doug's idea was to modify the circuit to allow for line level signals thereby using the wonderful sounding UTC transformers but having much less overall gain.  Because it would be a shame to not have some flexibility in the preamps, I used a switch in the level pot to activate another gain stage which means dynamic and ribbon mics can also be used.  

The power supply, besides having the correct looks to match the preamps, also utilizes an EZ81 for the high voltage supply and a series DC supply for the heaters.  The two meters on the front indicate the voltage (19 VDC) and current (1A).  


The Suprem Club Rehab Amplifier






Built for Jorge Gonzalez

This nice little amp was originally a Suprem Club amplifier, built in Germany in the beginning of the 1960's.  I bought it in terrible condition-- lots of rust, mouse droppings and spider webs!  However, the cabinet and the transformers were in decent condition so it made a great base for a rehab project.
As Jorge was looking for something that could be used in a small club setting and the studio, we decided on using 6V6 output tubes for a good balance between clean sounds and some tube overdrive.  The amp includes controls for gain (a pot that switches the input tube between pentode and triode mode), reverb, and tremolo (the indicator light flashes in time with the speed of the oscillator).  
One unique feature was something Jorge requested which actually makes a lot of sense, namely, a line-level input.  This comes in on a separate jack and eliminates the need for an external re-amp transformer as the line-level signal from a mixer or sound card can be plugged directly into the amp. As well, it makes overdriving the signal very easy, even at low volume, as there is a general volume control after this first input stage.  This would also be an easy mod on an existing two channel amplifier.


The Morse Code EL34 Bass Amplifier





Built for Jörn Magens

This is one of those times when the case really makes the project.  No changes were made to the case because it didn't need anything else-- the knobs, the VU meter, even the "porthole" were already there.  Originally, the unit was part of a morse code testing unit.  It is a big and heavy case but that is how a proper bass amp should be!

The amplifier has 100 Watts output into 2,4 or 8 Ohm.  As Jörn was looking for an amp that would distort more easily than the usual bass amp, EL34s were chosen as they need less drive.  Also included on the front panel is a knob to control the amount of distortion: similar to a power soak but without the wasted heat, this changes the phase inverter's bias.  Otherwise there are the normal controls of Volume, Tone and Mids.  As well, the switch next to the input lets the user choose between three different sounds-- lo gain, normal gain and a parallel mode which adds a little gain while boosting the low mids somewhat.  

Finally, a quick mention of the big black capacitors.  They are polypropylene and have an incredible lifespan, essentially making their replacement unnecessary.  Under normal conditions they should last well over 100,00 hours of use!  As a bonus, they make fantastic filter caps such that this is easily the quietest 100 Watt bass amp I have heard.  

The 235 Stereo Tube Spring Reverb Studio Unit





Built for Ben Boysen

The 235 Stereo Tube Spring Reverb Studio Unit is the latest development of the Rerun studio spring reverbs.  In this case the driver and return sections are pared down to the minimum-- there is no input control as the unit receives signal directly from an AUX send bus from a mixer or sound card.  From here the signal goes to a high pass filter which sets the length of the reverb from cavernous to room size.  

The 235 moniker comes from the fact that the unit uses a pair of spring units per side: one with 2 springs, the other with 3.  The difference between the two is subtle but each has its own uses.  With the switch in position 5 the springs are put in parallel for an even richer sound.  Due to the compact size of the case, the springs are external which allows for the elimination of hum and noise from the power transformer. 

Finally, all inputs and outputs are transformer balanced, the VU meter uses a switch to determine which signal to monitor and the case itself includes a classic Made in Germany tag!  In all, the compact size and simplicity belies the usefulness and variety of sounds possible with this unit.  

Diatherapuncteur Stereo Parametric Equalizer






Built for Øyvind Hågensen

This particular case comes from an interesting old medical device called the Diatherapuncteur.  The unit 
came with many strange and wonderfully-made devices that look they were meant to send a low level of 
current through the body.  

Øyvind was interested in having a sloped cabinet for the equaliser and I think this one stood out as a 
perfect example.  The 4 band parametric EQ circuit is based on an UREI unit because it was anything 
but clean and precise-- the application called for something extreme and wild so a tube front end and 
output was also included.  

Fully transformer balanced in and outs are included and all connections are made via tails coming from 
underneath the unit.  


The Golden Beetle Tube Vocal Preamplifier with Effects





Built for Sarah Bolen

The Golden Beetle began its life long ago as an Echolette guitar amplifier.  Unfortunately, when I received the chassis, both transformers were shot and heat damage to the PCB board made the unit irreparable.  Of course, the next best option is always to repurpose the case and here it has become a vocal preamplifier.

The first stage uses a pentode tube and 1:10 transformer to bring the signal to line level.  From here it is mixed with an instrument input and sent in parallel to various outputs via a cathode follower.  The parallel mixing allows the clean signal of the vocal to always stay true while adding distortion and reverb or delay.  As well, there is an option to add external effects for extra options.  

From here the signals are brought together via the individual level controls and a virtual earth mixer which feeds the equalizer section.  Finally, there is a paralleled ECC82 output section to drive the transformer for a low impedance balanced output.