Cat Scratch 50 FX Amp

Today I started the building of a new tube amp for one of my customers .

The amp will be a 50 Watts all tube circuit model of my own design and will have 3 channels ,clean ,crunch and lead,also on the amp I will put inside the chassis 3 analogue boutique effects pedals that will be switched from the front panel or by the included pedal-board.

The effects are Reverb, Chorus and Delay and when they are off they are true Bypass for keeping out of the amp circuit and not alter the sound of the valve circuit.

The idea is like having an all tube amp circuit with 3 effects placed on the effects loop path ,but in this case they are inside of the amp and when they are switched off is like they are not there at all and the amp circuit will remain all valve.

On the front panel will be all the controls for the channels and effects and on the back panel will be the various output jacks for the effects loop and output speaker jacks.

Also will be a recording output and a switch for the Tube Output valves working as a pentode or triode option.The output valves will be a pair of 6L6 GT.

Today I started to build the chassis from a sheet of aluminium an trued the edges of the sheet and opened the holes for the various pots,switches and jacks.

                  08/30/2012

   Continuing with the building of the chassis  all the holes for the various switches,jack sockets ,potentiometers,tube sockets and power supply transformer are now open.

 The next step was bending the front and rear panels for forming the chassis  and I made that with the aid of a metal bending tool that I made myself.The machine does a great job bending the aluminium to forming the box of what will be the chassis. After that I had to cut the two sides of the panel and then welding them in place.

  Aluminum is very difficult to weld  but with the new aluminium low temperature welding rods the job was done with success ,and now the chassis is ready for receiving a coat of ink to protect the aluminium from oxidation.

          09/10/2012

  Continuing with the amp construction now is time to start building the cabinet for the amp.    The cabinet will be made from Pine Wood because is a very nice wood when  finished .On this cabinet I will give a stain treatment before the final varnish be  applied to enhance the wood grain and give a more brownish color to the wood..                                                                                                                                         Also the pine is a very resonant wood and will increase the speaker response improving the sound quality of the amp.

After the staining I will give several coats of clear hard polyurethane lacquer to protect the wood from scratches and also let the wood resonate well.                        

    Softer lacquers or the more common used Tolex materials they act like sponges absorbing the sound and not letting the woods vibrate leading to a  decrease in the quality of the speaker and cabinet response. 

   I started by cutting the sides,top and bottom boards to the correct dimensions and then I made the finger joints that make the junctions of the four boards.          This   kind of junctions is very strong and prevents that the wood could move in the future,making a very tight joint of the cabinet,also on the finger joints I will apply some wood glue to make it even more strong construction.

After the cabinet was formed I applied the inside bars that serve as supports for the chassis and front speaker panel.

 On next time I will continue with the construction of the back panels and opening the holes for securing the chassis to the cabinet.

                    10/19/2012

     After some weeks without working on the amp,today I am back again  to continue with the project.

 I had to improve the stiffness of  my home made CNC machine because I need to use it to engrave the front and rear panels of the amp,and because the rigidity is not good enough and caused a lot of vibration that ruined the graphics when I try to engraving something with it.

   Now after some changes on the structure is good enough for engraving small letters ,but took me a lot of time to make the improvement .

  Today I returned to the amp cabinet and I build the front panel that supports the speaker and the the front frame that will cover the speaker after a wood grill mesh be applied on it .

 For the front grill I choose to apply the same kind of grill wood mesh that Mesa Boogie apply on some limited edition combos.I opted for this because I have it and the future owner of the amp wanted  it.

 After all this I finalised the day by doing the lower back panel.

On next week I will continue the amp work doing the front and rear face plates and engraving them with the graphics for the pots and switches .Now is time to enjoy the weekend.

3 thoughts on “Cat Scratch 50 FX Amp

    • Hi Paulo
      I have been working on my cnc machine for making it more precise in order to engrave the letters on the front and rear panels of the amp.
      That is the reason for holding the amp building but now the cnc is running fine and I will continue the amp work tomorrow !

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