Valve Spring Reverb

THE Dub Reverb Weapon
Capture d’écran 2021-04-18 à 22.24.04.
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Main board 


Official PCB board for my Spring Reverb ! 310mm X 200mm . Pretty large ! 

I try to push my limit as pcb designer but I learn intensive from last 2 years , almost every day . So i synthesis all the knowledge accumulated with the great help of wonderfull persons & Books , especially the Valve Wizard ones . I use the developpement board he design to make my prototype alive . I ask him if I have authorization to use it for my gears and stuffs . He say yes ( maybe  because in his "buisiness" this PCB board don't have the success they deserve) 

. For me it was just "WOW" , like a perfect balance between old school ( point to point ) and new school ( PCB boards )

Actually the "problem" for me is the time I spend to build gears for " you " . So with the numbers of mails about " my reverb " ....I decide to create a dedicated board ,  the specifications  here :


Preamp : 

ECC81 + input shielded transformer for balanced XLR / Jack input . Unbalanced connection avalaible too. DWELL control to varie the  signal send to the driver stage. That stage send a very strong signal that help to rattle the spring inside the tank . In Reggae Dub , we need it . Warm , Rich and Deep



Reverb recovery amplifier : 

Low noise 7025 Tube /   Parallele stage + Mofset follower for the  buffer EQ,

3 Bands EQ with "contour " shift via potentiometer ( it change the contour of EQ curves )  and  finally I add a Rotary switch 6 positions for cathode capacitors selectors with boost volume . EQ can be bypassed and create a slight boost to wet signal but with  the cathode selector always avalaible.

This part of reverb is really special and unique .A lot of different sound of reverb can be created with the same tank

In extra bonus I put a  passive saturator too at end of the chain.

This effectively adds some twangy "bite" to the sound of the distortion and will keep the sound from being too flabby.


Driver + high voltage transformer : 


6V6GT / 6K6GT or Mofset  Driver ( need a jumpers selection )  : Hammond transformer with 5K primary  or 8K Primary  choice with a 2 way selector .

Output Impedance is fixed at 8 ohms . 

You can also put a speaker and use the driver stage  as a small amplifier ( really cool for guitar / lead keaboard that need natural room characteristic . Tips : if you have a talkbox will try it for sure ! ( You NEED a cabinet with a 8ohms Speaker ) 

Last thing , a lightbulb compressor  is included ( On/Off ) .It " kill " some low frequency but can create a very cool effect on certains transient. In addition it s very cool to see the red light  flow arround the signal send  ! The Grampian reverb use a light buld too for information.


Power supply 

Maybe one of the most important part of any gears !  

I choose a Solid State Linear PSU with toroidal transformer shielded with 3 fuses protection and RFI shielded module.

The goal is to provide a very clean DC to the circuit .Especially for a Spring Reverb that have tendancy to be noisy . 

So i totally overkill the design in term of components , design and grounding sheme. 

8 smoothing capacitors that can handle more than 400VDC /  3W resistors for all plates distribution and DC distribution.

A CLC classique circuit revisited. That ensure a clean reverb sound with no buzz or hum . Like a good friend say , Hiss is hiss !  So yes a Spring reverb can hiss soon if you abuse on EQ and make bad gain staging . But if you respect some rules , it can sound very good / silent with flat value ( if tank is in correct condition and properly installed ) 

In addiction I choose a classic AC heater , because i join some little purist that claim that AC heater is just good for tube reverb sound . Placebo ? Don't know , but I keep it that way . With the board I put external connector . I use heavy twisted cable  close to the chassis to keep hum minimal . 

The DC elevation is balanced via a trimmed resistor so I can tweak it to the good sweet spot point 


 .In my studio with gain staging respected ( OVU calaibration )  , the noise appear at -105dbfs in my daw ( that record the master output of the mixing desk ) . That's good  :) 


If you research a reverb with a tons of fx , filters , lfo, gate etc  , I think you need to look elsewhere , other units exist and are good ( I hope :) . I will never say « I have the best gears on the planet .I just make circuit like I do for me. And love the Tube sound for a lot of gears

For people want a unique / classic  reverb sound with that  tube sound witch  create some unique harmonic distortion, yes is it . The passive design in addition of high voltage is special . Is better ? Not for all fi sure :)  , but it’s a YES for me,  especially for that reverb effect. 

Fender call it the « surf » reverb , because of the overkill driver that rattle the springs in really unique way

Ok , the convenient is the price , that why I create this PCB board , to minimize the time spend to build . But I don’t cheat . Look the price of a fender 3 tubes  6G15 clone ( for guitar amplifier )  .Imagine you have this one with a tons of mods  + with 1 stage added  ( SRPP Tube line out and 2 transformer for input / output ) so just the price of components is just ....expensive .The work on chassis , wiring , build add a big factor in price . 

I will propose this board as a complete DIY Kit , except the chassis .