About Revalverb Full Tubes design
Official PCB board for my Spring Reverb! 310 mm X 200 mm. Large enough !
I try to push my limits as a PCB designer, I have been learning intensively for 2 years, almost every day. So I synthesize all the knowledge accumulated with the precious help of wonderful people and books, especially those from Valve Wizard. I use the development board he designed to bring my prototype to life. I ask him if I have the authorization to use it for my gear and my business. He says yes (maybe because in his "business" this PCB does not have the success it deserves)
. For me it was just "WOW", like a perfect balance between old school (point to point) and new school (PCB boards)
In fact, the "problem" for me is the time I spend building tube reverbs for "you". So with the number of mails on "my reverb" .... I decide to create a dedicated card in a 3U, the specifications here:
Preamp:
ECC81 + shielded input transformer for balanced XLR / Jack input. Unbalanced connection also available. DWELL control to vary the signal sent to the pilot stage. This step sends a very strong signal which helps vibrate the spring inside the tank. In Reggae Dub, we need it. Warm, rich and deep
Reverb Recovery Amplifier:
Low noise 7025 tube / parallel stage + Mofset follower for better output impedance because the final output stage . The function of this preamp is to receive and amplify the pan / tank return. This stage is very important too
As an added bonus, I also put a notched passive selector to choose the reverb output texture with 3 Films capacitors .( call coupling capacitors )
Driver + high voltage transformer :
6V6GT / 6K6GT + Hammond transformer with 5K primary or 8K Primary choice with a 2 way selector .
Output Impedance is fixed at 8 ohms . ( Tank AB )
You can also put a speaker and use the driver stage as a small amplifier ,You NEED a cabinet with a 8ohms Speaker if used ( really cool for guitar / lead keyboard that need natural room characteristic .
Tips : if you have a talkbox ...you will try it for sure !
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 ( US 110-120V and Europe 220-240V )
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 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 Calibration ) , 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 .
A lot of demo is in my Facebook Profile HERE
and Audio 48khz 24Bits no master boost , no EQ or other Fx in the reverb path > DOWNLOAD
A similar reverb model is used in My Project with Marcus I and Horning Sound
https://horninsounds.bandcamp.com/album/2000-years-showcase