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New Tremolux 5G9 build --> input welcome!

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  • #31
    I would try to find any cap other than the Sprague Atoms. They are over priced and of questionable quality. Sometimes the leads on caps won't reach between the eyelets or turrets on vintage boards. This is unfortunate. If you know about it in advance, you can move the eyelets closer together or just solder some bare wire to the leads. It's ok to go to higher voltage if needed to get parts that are slightly larger.

    The small differences in capacitor nominal values usually don't make very much difference. The actual tolerance of the capacitance in an electrolytic is usually +/- 20% or higher. That's why you rarely see it quoted. In the past, when they were making tweed amps, it was -20%/+100%.
    WARNING! Musical Instrument amplifiers contain lethal voltages and can retain them even when unplugged. Refer service to qualified personnel.
    REMEMBER: Everybody knows that smokin' ain't allowed in school !

    Comment


    • #32
      Originally posted by klooon View Post
      Ebay seller: doublenickels_55. Great guy to deal with.

      If somebody wants more info, please send a private message to me.

      hi kloon,

      its sound like your doing a good job, alot detail goes into to an amp.
      what dimensions did you go with? Narrow panel,tweed tremolux
      1955: 16¾" x 20" x 9½" (42.5 x 50.8 x 24.1 cm) or
      55-60: 20" x 22" x 10" (50.8 x 55.9 x 25.4 cm)
      thanks dandrix

      Comment


      • #33
        Originally posted by Dandrix View Post
        hi kloon,

        its sound like your doing a good job, alot detail goes into to an amp.
        what dimensions did you go with? Narrow panel,tweed tremolux
        1955: 16¾" x 20" x 9½" (42.5 x 50.8 x 24.1 cm) or
        55-60: 20" x 22" x 10" (50.8 x 55.9 x 25.4 cm)
        thanks dandrix
        Hi Dandrix,

        The size of the cab is the original size for a 5G9 circuit, so that means: 55-60: 20" x 22" x 10" (50.8 x 55.9 x 25.4 cm), aka the big box tremolux (yes, a narrow panel, tweed). This is the same as a Pro cabinet, but then instead of a 15" now the 12". I thought that a 5G9 chassis would not be available, so I have chosen for a bigger cut-out in the cab so that it can fit a 5F4 Super (= 5E5A Pro) chassis. Now I have two extra knobs available, one will be a standby switch and the other will be used for a attenuator.

        You're right - a lot of detail. This is the first time that I am not building a kit. You have to search for every small component (grommets, standoffs, etc...).

        Comment


        • #34
          Originally posted by klooon View Post
          Hi Dandrix,

          The size of the cab is the original size for a 5G9 circuit, so that means: 55-60: 20" x 22" x 10" (50.8 x 55.9 x 25.4 cm), aka the big box tremolux (yes, a narrow panel, tweed). This is the same as a Pro cabinet, but then instead of a 15" now the 12". I thought that a 5G9 chassis would not be available, so I have chosen for a bigger cut-out in the cab so that it can fit a 5F4 Super (= 5E5A Pro) chassis. Now I have two extra knobs available, one will be a standby switch and the other will be used for a attenuator.

          You're right - a lot of detail. This is the first time that I am not building a kit. You have to search for every small component (grommets, standoffs, etc...).

          klooon,

          what about adding reverb? do think from your experience that you would have enough room? even using the 5f4 chassis? never thought of the pro cabniet for the replacement for the big box tremolux( with a different baffle board). good thinking!

          Comment


          • #35
            Originally posted by Dandrix View Post
            klooon,

            what about adding reverb? do think from your experience that you would have enough room? even using the 5f4 chassis? never thought of the pro cabniet for the replacement for the big box tremolux( with a different baffle board). good thinking!
            I have no experience adding reverb, would be interesting though. Maybe somebody else can comment on this?

            But my experience with tweed amps (5E3 Deluxe and 5F4 Super) is that they are quite airy! So you don't need to add reverb when you're in for some subtle reverb - of course if you want to go surfing, you need more.

            About 'enough room'. I think I am already stretching the space when putting the 4x 20uF caps on the board instead of on top of the chassis (cap can)...

            At the moment I am stocking up the parts (FR4 board, eyelets) and will be able to see if the caps will fit... To be continued...

            Comment


            • #36
              Layout version 8

              I got the advice to put the four 68k resistors on the input jacks instead of on the board to get rid of oscillations that may appear after a while.

              Further, I couldn't get (easy) a DPDT switch for the attenuator that is make-before-break (MBB). If you would use a break-before-make (BBM) there is no speaker load during switching, which is not okay for the OT. Therefore, I will use a 2P6T rotary switch (MBB) that I have lying around. I will use 3 positions:
              1) No attenuation (18 Watt)
              2) -3dB attenuation (= half power --> 9 Watt)
              3) -6dB attenuation (= quarter power) --> 4 Watt)
              I will use 10 Watt power resistors, but the maximum power per resistor is about 5 Watt (instead of one 15 Ohm, I use a combination of 8.2 Ohm and 6.8 Ohm).

              Here is the new layout (version 8):
              Click image for larger version

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              I ordered F+T caps (Frag Jan zuerst --- Ask Jan First) and I will use an FR4 board instead of the classical Fender fibre board. There are several reports about moisture problems with these fibre boards. Here is the board layout sketch (355mm x 70mmx1.6mm):
              Click image for larger version

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              and the (backside) board ready to drill (3mm eyelets):
              Click image for larger version

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              Comment


              • #37
                Work in progress

                Some pictures of the eyelet board.
                -drilled:
                Click image for larger version

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                -with eyelets:
                Click image for larger version

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                Click image for larger version

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                -populated with F+T (FJZ-AJF.de) and Russian PIO (mostly K40y-9) caps and Allen Bradley resistors:
                Click image for larger version

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                Last edited by klooon; 03-12-2012, 06:13 AM.

                Comment


                • #38
                  MM transformers received!

                  Today, I received the Mercury Magnetics transformers.
                  Thanks Chris for the excellent info and service @ CMW AMPS

                  PT: Axiom FTTP-M/E (0,100,120,220,230,240V | 320-0-bias-320, |6.3V|, |5V|)
                  OT: FTTO ToneClone
                  Choke: FC-TTREM

                  Looking at the PT and OT wires, I see some differences. Some of the grounding points are 'missing'. I rearranged the layout (and updated the colors). Is it right what I did to the layout? (version "9")

                  1) PT: No 0V wire for the Filaments --> I just deleted the wire that went to 'point (1)' at the grounding point of the first 20uF cap. Okay???
                  2) PT: No 0V wire for the Bias (50V) ---> I also deleted that wire that went to 'point (4)'. In the new layout I connected point (4) to (3). Okay???
                  3) Further, I added an eyelet ('x') next to and connected to point (6), because I could not put 7 wires into one eyelet...

                  4) OT: Grounding 'secondary' is connected to the OT and thus grounds to the chassis. --> I changed the grounding on the attenuator wiring. Not sure what is better: from 6.8R resistor to the ground of the output jack or close to the 6.8R to chassis????

                  Here is the version 9 of the layout:

                  Click image for larger version

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                  PLEASE NOTE: I added a wire from V2 pin 2 to 1M and 0.1uF (that I forgot in previous versions of the layout): fat blue line...
                  Last edited by klooon; 03-12-2012, 09:33 PM.

                  Comment


                  • #39
                    1.) No... you need to balance the filament string with some resistors.... 100 ohm 1/2 watt across the two leads with the common point of the two resistors at a quiet ground point in the chassis.
                    2.) Should be OK,,, the center tap of your high voltage leads... is probably the center tap.
                    3.)OK... but I don't subscribe much to the daisy chain grounding method or the daisy chain to star ground method. You have the first preamp, the input jacks and the phase inverter all grounded to the same place. I'd ground the input jacks, and the last 20uF-500v cap differently.
                    4.)I don't even know what the heck you are doing there with those resistors, attenuation and the ground point of the jack. Chassis grounded is usually OK here.
                    Bruce

                    Mission Amps
                    Denver, CO. 80022
                    www.missionamps.com
                    303-955-2412

                    Comment


                    • #40
                      Thanks!
                      1) and 2): okay!
                      3) I have to digest this and see what are the options now.
                      4) regarding the attenuator (-3dB and -6dB), this is the layout (the total resistance stays very close to 8 Ohm (both 7.8 Ohm)):

                      Click image for larger version

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                      Originally posted by Bruce / Mission Amps View Post
                      1.) No... you need to balance the filament string with some resistors.... 100 ohm 1/2 watt across the two leads with the common point of the two resistors at a quiet ground point in the chassis.
                      2.) Should be OK,,, the center tap of your high voltage leads... is probably the center tap.
                      3.)OK... but I don't subscribe much to the daisy chain grounding method or the daisy chain to star ground method. You have the first preamp, the input jacks and the phase inverter all grounded to the same place. I'd ground the input jacks, and the last 20uF-500v cap differently.
                      4.)I don't even know what the heck you are doing there with those resistors, attenuation and the ground point of the jack. Chassis grounded is usually OK here.

                      Comment


                      • #41
                        Here is a new version of the layout (v10).
                        Click image for larger version

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                        - I have put the 2x 100R 1/2W resistors for the virtual center tap on pins of the the second 6V6.
                        - I have added two gridstoppers --> 1k5 1/2W between pins 5 and 6 and lead the wires from pins 6 to the 220k's.
                        - For the grounding, I will stick to the current layout for the moment (maybe there are more 'best' options ;-) ). I will make some changes later if this version is not satisfactory.
                        - I have rearranged the orientation of the input jacks a little bit (more like they do in the blackface Fenders).

                        Comment


                        • #42
                          Are your input jacks insulated from chassis ground for some reason? If no, you do not need those black wires connection all the ground lugs.
                          With the 68K resistors up on the jacks, you might want to consider using shielded cable from the jacks to lug 2 and 7. Ground the shield at the jacks and leave the other end of the shield trimmed back and not connected to anything.
                          I'd still break that lead from #11 to X.
                          You do not need that extra wire from lug 8 of the power tube to the bottom of the bias supply rail.
                          And there is a small chance your bias supply will create a power tube hum with the filter caps and trim pot wired that way.
                          Bruce

                          Mission Amps
                          Denver, CO. 80022
                          www.missionamps.com
                          303-955-2412

                          Comment


                          • #43
                            Hi Bruce,

                            Thanks for your comments. I made changes to the layout (now new version 11):
                            Click image for larger version

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                            - Re input jacks: they are all ground to the chassis. So I have removed the extra wiring. (in my previous ('hum-free') 5E3 build I connected these extra wires to a bolt on the side of the chassis - a bit like my version no. 4 of this thread).
                            - Re shielded wire: what kind of shielded wire do I need??
                            - Re break the lead of #11 to x: Okay, fine --- although I cannot oversee the consequences (for me the grounding is still a bit of 'magic').
                            - Re extra wire lug 8: Yes, of course, I can see the point!
                            - Re bias supply wiring: what would be a better wiring design??
                            Last edited by klooon; 03-19-2012, 07:01 PM.

                            Comment


                            • #44
                              Updated layout (version 12):

                              - I found an error in my previous layouts. 320V wires should of course go to pins 4 and 6 (instead of 3 and 5).

                              - I changed the ground layout. Instead of point 3 to x, I changed this to point 4 to x. Can someone let me know if this is fine?

                              Click image for larger version

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                              Last edited by klooon; 03-28-2012, 06:51 PM.

                              Comment


                              • #45
                                Originally posted by Bruce / Mission Amps View Post
                                And there is a small chance your bias supply will create a power tube hum with the filter caps and trim pot wired that way.
                                What should I do to improve the bias supply wiring??

                                Comment

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