Tube reverb driver circuit

The output of the preamp stage is sent to three places. Fender amp preamp tube layout and recommendations kca. The amplified current is sent to the reverb tanks input transducer. It uses a single, less than one dollar tl072cp op amp as the reverb driver and reverb recovery amps. This is necessary to conform to modern day nemko safety requirements. Spring reverb tanks explained and compared antique electronic. The commonly used driver circuit drives a low impedance tank via a small transformer. Can i use 12 a tube to drive the reverb and the other 12 as the recover. The reverb circuit uses one triode of a 12ax7 half the tube and one whole 12at7 tube.

The wave is a versatile standalone, tubedriven analog springreverbunit kit. What other items do customers buy after viewing this item. The design of the reverb driver section is not exactly the same as the design used in the fmi 93 super amp. Some fender amps use one tube to activate the reverb, and other fender amps use two tubes. Cr7 56v zener protects c4 from exploding if v2 develops an internal short. Real tube by tube works other than one being in super cool enclosure, and the other in a buttugly enclosure, the 4 knob 911 tube drivers and 5 knob real tube versions are basically the same patented b. Because of the high demands placed on this tube by the fender reverb driver design, its important to get a good quality 12at7 for this slot. How to troubleshoot the reverb on fender amps our pastimes. Replace the tubes with duplicate tubes, and test the reverb. A modified schematic, based on the original fender 6g15 reverb unit, but updated. It is important to match the original tank input and output impedance as closely as possible in order for the reverb effect to work properly. Butler designed tube driver circuit with some component differences. Compatible with all electric guitars and amplifiers.

Reverb tanks are available with input impedances from 8 ohms to a few k ohms. You can think of the reverb driver circuit as being a fender champ running inside a larger amp circuit. The 10pf capacitor in parallel with the reverb mix resistor is simply a bright cap. Fourth tube is the driver and reverb recovery amplifier. Handwired circuits will always sound better than printed circuit boards. The ones buit for solid state are much lowered impedance than those for tubes. You should be able to get a new 12ax7 tube and swap it out with the faulty reverb tube. Tombolas diy spring reverb driver circuit 8th july 2012 ive been fiddling with spring reverb for a while, probably because of reading gabriel roths famous shitty is pretty article in the late lamented big daddy magazine, where he talked about his way of using spring reverb on his throwback funk. From studying old tube amp schematics it seems the reverb portion of the circuit is usually after the the preamp, but obviously the pedal configuration of the stage center would need to be placed before the preamp unless you put it in an fx loop. The lamington reverb was designed as a stand alone reverb unit and that application requires quite different design to a built in reverb. Better 12at7s notably, the mullard cv4024, mullard ecc81 or rca 12at7 s will also improve the tone of. The 1965 m10a switched to a tube recovery section and moved the reverb level pot to the other side of the tube its predecessor, the 19631964 m10 used a transistor recovery. All these components will drift during age and minor differences in component values are noticeable to mans ear.

This means that under ideal conditions infinite load the tube could deliver a. A quick look at your circuit shows that the use of v1a as the reverb preamp means that when reverb is switched in, the dry signal only has two rather than the three gain stages required for the lamington. Fender used a parallelled 12at7 as an output tube for some tanks. More information on reverb tanks is also available at rod elliots site. Read the instruction manual for your fender amplifier. Two controls allow you to serve up a wide range of wetness from just a touch to over the top psychedelia. The reverb driver amp consists of a phase inverting pushpull circuit made from dual sections of a 5532 high quality audio opamp. Im doing an amp project and id like to include reverb in it, but i only have three preamp tubes, one of which is the pi. Guitar signal enters at upper left and gets amplified by the reverb driver both stages of a 12at7 tube in parallel then flows into the reverb transformer which trades high voltage for current. The amplifier and output transformer that drive the tank, the tank itself, and the final.

Reverb driver question12ax7 vs 12at7 a guitar forum. Lets say that you have an amp with a power transformer that could supply the heaters and high voltage for an additional small signal tube like a 12dw77247. The drive coil has a nominal impedance specified at 1khz. Theres a limiter circuit on the input of the tank because. The overall circuit is broken down into three sections. The amplified current is sent to the reverb tanks input transducer see tank detail below.

Not all amplifier models of the same name use the same transformer model. The footswitch turns the reverb on and off by grounding the input to the reverb recovery circuit. The lamington reverb a better valve reverb unit valve. The best reverb driver tubes telecaster guitar forum. The driver was feed from the second stage via a voltage divider and the recovery went to the effects send via a mixing resistor.

The driver is a parallel 12au7, and there is no cathode bypass capacitor so the cathode resistor of 270. The reverb circuit is inserted just before a guitar amplifiers phase inverter in a pushpull amp or just before the driver last gain stage before the power tube in a. Reissues also have two printed circuit boards potentiometers are mounted on the smaller of the two and a mix of hand wiring and spade connectors. The tube was used in a number of american guitar amplifiers.

This one was inserted a little bit different than the usual way. The schematic i have for a reverb circuit calls for using both sides of the tube as the driver. This simple, inexpensive spring tank reverb circuit is taken from the fender hot rod deluxe. How to build your own spring reverb unit all things. A transformerless constantcurrent reverb driver introduction. I may be wrong, but i think the reverb tube on the super reverb is the. Dwell sets the signal level entering the reverb circuit, and tone is a simple. The mosfet driver is based on the legendary bk butler tube driver. Suggest a 12ax7 with high gain and reasonable quality, though very low noise or hum might not be required. Many notable players have achieved this with other lowergain tube types, the late stevie ray vaughan for one, who often used a 5751 somewhere between a 12ay7 and a 12ax7 gainwise in his amps first position.

But that is not the only way to drive a reverb tank using a vacuum tube, and in fact it is not the best way. Some changes in the circuit were made to accommodate a 6v6 reverb driver tube, replacing the obsolete 6k6. The ampbased version is just as much a real tubedriven spring reverb circuit in that it carries a small ot to drive a portion of the signal through a longspring pan, but instead of the reverb units large 6k6 output tube, 12at7, and 7025 a 12ax7 type it uses just the latter pair, one as driver and one as recovery tube. Vacuum tube reverb circuits traditionally have used a lowimpedance reverb tank coupled to the driver tube by a small output transformer. Td752 tube driver comb amp tube works same as the td742 combo amp above, but this is a 100w version with additional features. So if youve got a circuit board thats problematic, the problem was built in to the design, its not central to the quality of the material.

And this was in two different fender tube reverb circuits a brownface and a blackface. The filtered signal then gets boosted by the reverb driver amplifier. Spring reverb tanks explained and compared antique. This article considers only the driver stage, and not the reverb recovery stage which is usually a simple triode gain stage, unfortunately. Spring reverb tanks explained and compared the reverberation effect.

For example, fender typically uses two parallel sections of an 12at7 in a class a single ended circuit as the reverb tank driver in their tube amplifiers. A pair of adjustablebias mosfet gain stages take the place of the 12ax7 vacuum tube, otherwise the. Just gently tap on all the tubes and see if one makes lots of noise. The best reverb driver tubes discussion in amp central station started by yamatele, feb 3, 2011. Some time in 1966 or 1967, valco started using a hammond reverb tank instead of the cardboard box tank they had been using since 1961 this particular circuit used the 6973 power pentode as a reverb driver coupled with a singleended output transformer. I often find a weak reverb is the wrong tank for the circuit. Find out which tube is responsible for controlling the reverb unit. The dc conditions have been verified to hold true up to about 500 khz, well beyond the capabilities of the driver tube. Featuring a unique circuit design, the mxr fet driver captures the rich, creamy sound of an overdriven tube amplifier by cascading an opamp gain stage into a fet stage.

I have even seen some bargain bin circuits that are simpler than that. Getting 17v rms at 6khz is easy, and only needs an input voltage of a little over 1. The reverb circuit is inserted just before a guitar amplifiers phase inverter in a pushpull amp or just before the driver last gain stage before the power tube in a single. The ampbased version is just as much a real tubedriven spring reverb circuit in that it carries a small ot to drive a portion of the signal through a longspring. A follower whether tube, bjt or mosfet is used when you want to transform an rather high impedance tube plate into a low impedance reverb tank.

Driving a reverb spring tank presents some challenges. Please make sure the amplifier transformer which you are replacing has a fender number matching. The 629052agvc9052a came equipped with a very nicely designed reverb circuit. Hobbyists and amp builders can now use some of the same highquality transformers and chokes found in london powers own amp line.

As seen from figure 4, the actual reverb drive coil impedance varies over a wide range, but that will not cause stress to the driver circuit shown in figure 7. Although the previous circuit produces reasonable results, it is not without its. Fender licensed the reverb circuit from hammond and surf guitar was born. A 2n3906 pnp tranistor is used for a low noise design on this stage. The reverb circuitry consists of two tube sections reverb driver v3 and reverb recovery v4 and the physical reverb tank. To be clear, it requires a small power amplifier, rather than voltage amplifier to drive it, so you would have to reproduce that circuit. Information on driving spring reverb using valves tubes seems to be rather. Hoffman amplifiers tube amp forum, ss spring reverb.

Depends on the reverb tank, but you can substitute a 12at7 or 12au7. Notable is the dynaco st70 stereo amplifier introduced in 1959 which used a. A reverb tank takes a small amount of power to drive it. Tube reverb driver circuits the amp in question used a primitive solid state driver straight from the guitar input and returned the reverb signal via the cathode of the first 12ax7. Aa763ab763 tube layout seen from behind, v1 is to the right side v4 12ax7 12 reverb recovery and 12 gain stage for vibrato channel. Big difference is headroom and reliability of the tube. A reissue of the original tube reverb was introduced in 1994 and manufactured through 2016.

There are many varieties of tube and solid state drive and recovery circuits used in guitar amplification resulting in different input and output impedances. The fet driver thickens up lead tones with musical, amplike distortion and sustain without the fragility and inconsistency associated with tubes. See the note on the archived circuit diagram pdf above the reverb driver tube from dave zerycks california dreamer plus v 2. It is important to match the original tank input and output impedance as closely as possible in order for the reverb. Heart of the tube driver is a real handselected 12ax7 tube by bk butler himself. The driver circuit is basically just a normal grounded cathode stage but with a beefy tube and a pretty high idle current and therefore low output impedance which is needed to drive the tank. Use an input highpass filter to compensate for the input coils inductive reactance. Preferred series 7025 and tungsol 12ax7 are suitable, 5751 not recommended. It can be used in front of your guitar amp or as a linelevel analog reverb effect for the recording studio. Transformerless reverb driver channel road amplification. How to build a tubedriven spring reverb module based on classic. The drive circuit for any spring reverb tank is critical by far the most critical part of the final system. The input transducer of a reverb tank is a coil of wire wound around an iron core. The usual choice for a tube amp is something in the 1 to 5 k ohm range, which can be driven from a dc blocked tube plate.