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London Power Standard Amp

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  • #16
    Nice link!
    Thank you!

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    • #17
      Hello LooseChange,

      I don't know if you're still checking this thread or not, but I'd be very interested in hearing about some of the mods you did and why you did them.

      I'm currently working on a scaled down version of the Standard. It will only have a 2xEL34 output. I'm also ditching the FX loop, body & limit controls, triode/pentode switching, and line out.

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      • #18
        Ptron,
        Yes, I check in when I can.
        I am working on a new build myself with many changes. See the Standard II on my website:
        www.loosechange.freeservers.com

        The types of mods are mainly value changes and switch options as related to your build.

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        • #19
          Nice job! I see you've opted to drop the "dual" output stage too. Tube rectifier too, eh. It looks like your keeping the "body" and "limit" controls. It also looks like you have the power scaling card in there but no controls, is this right? You said something to the effect of it not being that useful for you. I'm curious if that's because you don't like the way it sounds or if you just usually need all the power. The power scaling is the main thing that drew me to this amp. I bought TUT mostly to get the schem for the power scaler and add it to my own design. When I saw the standard I realized it was pretty close to what I wanted and probably much more likely to sound good than some crap I just made up

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          • #20
            No body, no limit and no powerscaling in the Standard II. I added the tube rectifier because I like the sag best. I didn't really find much use for the powerscale.

            I like the effects loop and reverb. On this amp, I concentrated more on the switching preamp.

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            • #21
              I almost left the reverb off, but I will probably occasionally use the amp with pedal steel, so I dicided to go with it just for that. I only use floor pedals so the effects loop is pretty useless to me.

              What I'm curious about is why you don't find the power scaling useful. Do you think it sounds funny or do you just like the full headroom?

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              • #22
                Exactly, I built the amp to play with my band. It's really no use.
                I find the parallel effects loop great for time based effects like my Memory Man Delay. It puts the effect exactly where it belongs in the signal chain.

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                • #23
                  looks like you've changed up the rest of the power supply as well(besides dropping the power scaling). Are you just getting the -bias and switching voltage off a leg of the HTsecondary? I've wonder why Kevin O'Conner chose the complex method he did to derive the -V supply. For those who haven't seen it, he uses The 5V secondary, normally used for tube rectifiers, and steps it up with second transformer. This seems unnecessary to me: extra transformer, extra winding on the PT. Doesn't seem like the switching circuit would draw enough current to worry about. Maybe the power scaling causes more current to be drawn from the bias supply than normally would be.

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                  • #24
                    I went traditional on the power supply filtering because I used a Tube Rectifier. My B+ is at 460 with the 5AR4 so I had to beef it up.
                    I used a Weber transformer which is very well suited for this project. It has two sets of HT windings 720 and 660. I used the 720 for the B+ and I built my V- (bias) off of the lower winding (set at max of -75v). The transformer also has a Bias winding which I used for my switching card (derived -18v).

                    I guess I really can't call it a Standard anymore. I'm looking for another name.

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                    • #25
                      What did you use for the reverb transformer and pan? All I can see in TUT5 is that it says "316" for the transformer. This doesn't appear to be a Hammond #.

                      I just now noticed that this amp has no standby!?! What's up with that? There's no soft start circuit.

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                      • #26
                        The 316 is a proprietary transformer that London Power has produced. You need to buy it from them. The only way around is to change that part of the circuit to a Fender type and use the everyday single ended transformer.

                        There is no standby on the "Standard". If you read TUT books they explain it's not needed on low power tube amps like this one.

                        My newest build is a Standard lookalike with the Fender style reverb circuit, a standby, no powerscale, a tube rectifier and only 2 power tubes. Take a look at that.

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                        • #27
                          Update - long overdue!
                          I finally went back and changed around the powerscaling. I am now powerscaling only the power tubes. I like it. It seems to give me better tone when I scale back for more power tube distortion.

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                          • #28
                            Great thread Dan, I will be building a Standard in the near future.

                            Mike

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                            • #29
                              Originally posted by teleamp View Post
                              Great thread Dan, I will be building a Standard in the near future.

                              Mike
                              Let me know how you progress. I can add some wisdom as you build.
                              Dan

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                              • #30
                                Haven't really worked on it since. My hobby time has been spent building a few pedals and playing in four bands, but I'm starting it up again. I was going to drop the reverb and the reverb mix/gain recovery stage (as well as the fx loop) http://music-electronics-forum.com/s...ead.php?t=3132

                                One of my main goals is to simplify the amp and make it as light as possible. (see the line about playing in four bands and think about all that amp schlepping) This was supposed to allow me to use the Hammond 272FX instead of the original JX, saving 4 lbs. I thought the 150ma rating was enough but now I see this thread which blows that whole idea to hell
                                http://music-electronics-forum.com/s...ead.php?t=3235

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