Rewiring reverb tank in mid 1960s gibson guitar amp all. The driver was feed from the second stage via a voltage divider and the recovery went to the effects send via a mixing resistor. Use an input highpass filter to compensate for the input coils inductive reactance. Just like in the case of the driver above, the details of the circuit can reveal the z out characteristics of the reverb tank. The black art of reverb steve carr explains circuits and troubleshoots common problems. This driver tube and the reverb transformer are a small singleended output stage, and if there is no load from the tank the reverb transformer can be damaged just. Everything i know about spring reverb music thing modular. The question is how would you go about installing a reverb tank in an amp without the driver circuits for the sendreturn, mix or level controls. The amplified current is sent to the reverb tanks input transducer see tank detail below. Without the transformer, one of the opamp outputs may be shorted to ground at the reverb case.
To be clear, it requires a small power amplifier, rather than voltage amplifier to drive it, so you would have to reproduce that circuit. The commonly used driver circuit drives a low impedance tank via a small transformer. I do not use this resistor on any of my reverb circuits. Solid state spring tank reverb circuit telecaster guitar. Driver circuits were all working though the tank was not. Care and feeding of spring reverb tanks elliott sound products. I am planing on putting a tank in a champ sized amp, a 17 length might be a bit much. This one was pulled from a wurlitzer ss amplifier with 4x8 speakers. Six springs, counterwound, coupled and placed in parallel, combine to create sound enhancements fullest, richest reverb effect throughout the full range of musical sound. I also added a 1k drive pot instead of the 660r resistor. 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. For most mesa amps with tube reverb circuits, the reading at the shielded cables jack will be approximately 200. The reverb circuit is inserted just before a guitar amplifiers phase inverter in a pushpull amp or just before the driver. Ideally suited for keyboard, sound reinforcement and pedal steel applications.
No way to test them currently but the folded line lo. The input and output transducers can be characterized as essentially inductive, with impedance rising with increasing frequency inductive reactance. I have a fender 3 spring reverb tank that i would like to set up so it can be used. I heard that using a 12ax7, which is a higher gain tube, would make the reverb strongerdeeperwetter but elsewhere i heard that it is current and not gain which would increase the reverb and that the 12at7 is higher in current than the 12ax7. Beltonaccutronics reverb tank 4ab3c1b long 2 spring long. Using a high impedance tank and a constant current pentode driver that eliminates the drive transformer, it is possible to build a simpler and superior spring reverb unit. I think the biggest improvement will be noticed in head setups because they tend to have noisier reverb circuits because of the tank being so close to all the other stuff in the head, like transformers. The input impedance to the reverb tank is almost purely reactive and proportional to signal frequency. First test if your spring will reach both sides, then glue the speaker and piezo into the box.
Nov 12, 2017 everything i know about spring reverb an mk2 version of music thing modulars spring reverb module went on sale this weekend. Connecting to and from the spring reverb and the tank driver is easy and. This particular circuit used the 6973 power pentode as a reverb driver coupled with a singleended output. Playing amp with reverb tank removed the gear page. Hi, id like to make a lofi pedal or tank with an actual spring reverb unit mod, accutronics, etc. Im not sure if it will definitely work but the first tank i would try is the 4ab3c1b. This helps a lot when switching in different spring tanks via the handy phono jacks on. Transistor recovery on early magnatone amps 19611964, the reverb tank s output is connected to a potentiometer, like in the 480 schematic below. These are some notes about what the module does, how it.
On some amps you can remove the tank, then connect the amps out jack to the in jack via a pot, and use the reverb circuit as a solo gain circuit. I recently purchased a used mid 60s gibson explorer amp ga15rvt. Just be sure you connect the low impedance end of the tank to the driver amp, and the high impedance. One of the previous owners for some reason removed the amps reverb tank so my goal is to install a new reverb tank and get the reverb working. In addition, a plugpack power supply similar to the one used in the lamington junior amp can be used to. My friends fender amp the reverb would not always work. Rewiring reverb tank in mid 1960s gibson guitar amp home. The drive coil has a nominal impedance specified at 1khz. In addition, a plugpack power supply similar to the one used in the lamington junior amp can be used to simplify the power supply and make it a cheap build. The labor intensity of building handwired amps, whether truly pointtopoint or using handwired eyelet or turret boards, means that these often cost more than amps built with printed circuit boards pcbs. The lamington reverb a better valve reverb unit valve. These are some notes about what the module does, how it was designed. You would also need another 12ax7 section on the output to amplify the reverb tank output to something actually useable. With the tank driver, you can take any balanced line level signal or.
How to build your own spring reverb unit all things. Accubell specifies that the signal should rise 6 db per octave to deliver constant current over the frequency range, or to use a constant current driver circuit. Bass drives more current and can unpleasantly dominate the reverberated response. Ryan shoots out the stock accutronics 47604 against the mod 4ab3c1c. Check the resistance of the reverb tanks output using an ohmmeter. Released in 1981, the pro one featured a single voice but two oscillators for added sonic flexibility, a fourpole low pass filter, two adsr envelope filters, along with an arpeggiator and a very. One reader reported having good results using a mouser 42tu0 1k to 8 ohm transformer. Glue it to the inside of your box with the glue gun. To do this, put your ohmmeter leads across the tip and shield of the reverb tanks return cable the shielded cable.
To mitigate this effect, fender attenuates bass through the use of a tiny, 500pf coupling capacitor between the secondstage voltage amplifier and the 12at7 grids. The transformer adapts the dual opamp output impedance to the reverb driver coil impedance. From the schematic floating around online, this amp has a reverb driver transformer with an 8 ohm secondary. With a decent reverb spring tank in overdrive, this circuit will produce an incredibly thick and grungy sound. Hoffman amplifiers tube amp forum, ss spring reverb. A transformerless constantcurrent reverb driver introduction. Guitar reverbs require a reverb tank driver on the input of the tank. Use the 12au7 side for the driver and the 12ax7 side as the recovery. The folded line is the same model found in roland space echo. A look at an accutronics spring reverb themaritimegirl. It also serves to isolate the ground on one side of the reverb coil from the opamps. The reverb circuitry consists of two tube sections reverb driver v3 and reverb recovery v4 and the physical reverb tank.
Built the stage center as a stand alone unit with the spring reverb tank inside it was a pedal that is about 35 cm long by 15 cm high and wide. The reverb circuits on this page arent guitar stomp boxes. The accutronics tank came from a webb steel guitar amp with a 15 speaker. Avoid mounting the outer channel of the reverb tank directly to the mounting surface by using grommets, rubber standoffs, reverb tank bag and liner or other products designed for mechanical isolation. 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. R17, a 220k resistor was added to the reverb recovery circuit. This simple, inexpensive spring tank reverb circuit is taken from the fender hot rod deluxe.
Drill holes for the pots of your amp, jack inputoutput, light if your amp has one. I put it right before the amplifier if using it as a reverb unit for guitar. This one was inserted a little bit different than the usual way. Information on driving spring reverb using valves tubes seems to be rather. I have a fender 63 reverb clone and a princeton reverb ii both of which use a 12at7 to power the reverb.
Handwired circuits will always sound better than printed circuit boards. The drive circuit for any spring reverb tank is critical by far the most critical part of the final system. Wetness seems to be effected by how hard you drive the tank, how long the tank is, how many springs the tank has and how much gain you have in recovery. Driving a reverb spring tank presents some challenges.
This article considers only the driver stage, and not the reverb recovery stage which is usually a simple triode gain stage, unfortunately. Unlike driving a speaker, the drive signal to a reverb tank is ideally not flat, with respect to frequency. Forrest cook this is a circuit for a guitar spring reverb pedal, it has dry, wet, and drive controls for a wide variety of sounds. R16 was added to present a load to the reverb output transformer secondary winding in case there was no reverb tank plugged in. The drive coil has a nominal impedance specified at 1khz, but it also has considerable inductance. This driver tube and the reverb transformer are a small singleended output stage, and if there is no load from the tank the reverb transformer can be damaged just as with an output transformer with no speaker load. This resistor is standard on most fender reverb recovery circuits on the reverb combo amps. Although the previous circuit produces reasonable results, it is not without its. I suggest you try googling driver amplifier for spring line reverb.
One of the previous owners for some reason removed the amps reverb tank so my goal is to install a new reverb tank and get the reverb working again. Single 12ax7 reverb circuit telecaster guitar forum. If you can spare 3 triode elements, then a medium impednace tank driven by a ssrp and recovered by a 12ax7. Nov 14, 20 i have a fender 3 spring reverb tank that i would like to set up so it can be used. Spring reverb tanks explained and compared amplified parts. If building for a spring, ignore all components in.
The real tank sounds better, but is physically bigger and liable to hum. The driver stage also requires a voltage amplifier to drive the reverb tank driver, meaning you would need at least a single 12ax7 section to drive the 12at7 tank driver. Vacuum tube reverb circuits traditionally have used a lowimpedance reverb tank coupled to the driver tube by a small output transformer. Spring reverb tanks explained and compared antique electronic. I extended the wires for the battery compartment and. Transformerless reverb driver channel road amplification. And finally some short demos with the specified 3 spring 8eb2c1b tank, just to give an idea of what it sounds like. Vaguely recall the amps coming with a short tank but later ones with a long one. The brick is small and selfcontained, with a distinctive reverb based on pt2399 delay chips. From dave smith of todays dave smith instruments, the sequential circuits pro one is a lowercost, monophonic adaptation of the classic prophet 5. Rewiring reverb tank in mid 1960s gibson guitar amp. The 629052agvc9052a came equipped with a very nicely designed reverb circuit.
The output of the reverb tank is sent to the reverb recovery amp, it is also a 2n3906 class a low noise. Reverb tank short tank for tube reverb circuits mesaboogie. Oct 14, 2017 a look at an accutronics spring reverb themaritimegirl. I was able to repair the original reverb however the new reverb tank sounded better was more vivid and present. 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. More information on reverb tanks is also available at rod elliots site. The lamington reverb a better valve reverb unit valve heaven. This tank driver is an amplifier with a high impedance front end. Spring reverb a flexible, easytobuild voltage controlled. Reverb tanks are supplied in a variety of input and output impedances measured at 1khz to allow for flexibility in designing drive and recovery circuits. For the reverb driver i have used a 1 watt amplifier n48fl see attachment i have got this to drive the strings in the reverb tank quite nicely but only when i power it with a 12v dc supply connected in parallel with a 9v battery. Accutronics products and specifications amplified parts.
It uses a single, less than one dollar tl072cp op amp as the reverb driver and reverb recovery amps. A modern reverb tank consists of drivers, transmission springs, pickups, and a. 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. Reverb tank short tank for tube reverb circuits mesa. Dec 08, 2017 ryan shoots out the stock accutronics 47604 against the mod 4ab3c1c.
The amplified current is sent to the reverb tank s input transducer see tank detail below. Everything i know about spring reverb an mk2 version of music thing modulars spring reverb module went on sale this weekend. If you can find a reverb tank with a high impedance driver coil, the transformer may be eliminated, the driver coil will require isolation from ground. All these components will drift during age and minor differences in component values are noticeable to mans ear. If you choose to unplug the tank in your fender amp, also remove the 12at7 reverb driver tube. The input transducer of a reverb tank is a coil of wire wound around an iron core. This is the standard tank used in fender amps which as also use reverb driver transformer with an 8 ohm secondary. How to build a tubedriven spring reverb module based on classic ampeg and swartstyle circuitry that can be retrofitted to loads of different.
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