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  • #16
    This is the inside of a 1987x re-issue, mine is a SLP re-issue but I think you'll get the idea:



    Close pic of the PSK...

    Comment


    • #17
      Who did your install?

      I'm thinking of doing it myself. But will probably pay to have someone else put it in, or at least help me out if I run into problems.

      I'm also thinking about swapping out the PCB with a PTP. I didn't know they made one until this guy told me about it over at 18watt dot com. I'm posting about it over at metro amp forums.
      Hold on to your dreams

      Comment


      • #18
        Originally posted by 1_Way
        Who did your install?

        I'm thinking of doing it myself. But will probably pay to have someone else put it in, or at least help me out if I run into problems.

        I'm also thinking about swapping out the PCB with a PTP. I didn't know they made one until this guy told me about it over at 18watt dot com. I'm posting about it over at metro amp forums.


        Mark Stephenson did it (www.stephensonamps.com)

        I'm not a big fan of PCB vs PTP in a Marshall. I'm more leaning towards changing the OT for overrall improvement in tone.

        take a look a www.obsoleteelectronics.com.

        Comment


        • #19
          begin_etienne
          I'm at a cross roads concerning doing one of two things. I will either do Power Scaling, or Power Attenuation (and optionally proceed from a full dummy load setting through a line out into a clean sounding slave amp, whatever works best).

          My question about Power Scaling is about what the amp sounds like before and after the mod has been done. The skeptics say that when you install the Power Scaling Kit, it changes the amp such that it is no longer the same amp. This change might not be a significant change, I am wondering if it is noticeable or not.

          Did you have your amp long before you had the kit installed and did you notice any sonic changes after having the kit installed?

          Opps, if I remember correctly, you also upgraded one of the transformers... Did that happen at the same time? If so then I suppose that it would not be possible to discern which mod made any sonic differences. Any help here would be appreciated.
          Hold on to your dreams

          Comment


          • #20
            begin_etienne
            ???
            Hold on to your dreams

            Comment


            • #21
              Originally posted by 1_Way
              begin_etienne
              I'm at a cross roads concerning doing one of two things. I will either do Power Scaling, or Power Attenuation (and optionally proceed from a full dummy load setting through a line out into a clean sounding slave amp, whatever works best).

              My question about Power Scaling is about what the amp sounds like before and after the mod has been done. The skeptics say that when you install the Power Scaling Kit, it changes the amp such that it is no longer the same amp. This change might not be a significant change, I am wondering if it is noticeable or not.

              Did you have your amp long before you had the kit installed and did you notice any sonic changes after having the kit installed?

              Opps, if I remember correctly, you also upgraded one of the transformers... Did that happen at the same time? If so then I suppose that it would not be possible to discern which mod made any sonic differences. Any help here would be appreciated.


              I have done plenty of testing, not with an SLP but a 1987x. Mark Stephenson did the mod to my friends 1987x way before my SLP.

              The amp sounds exactly the same, and will still give the available maximum output. Marshall Maniac (over at www.vintageamps.com) had issues when he installed it and documented that problem. He had installed the kit himself and did something wrong, not sure if he updated his document.

              The amp sounds extremely different at low volumes, compared to its unmoded version at low volumes. Between .5 and 1 watt, the speakers are getting pushed, and you will get all the thickness and harmonic richness. On the other hand, at the same (low) volume, the 1987x w/o the PSK sounded extremely bright, punchy and thin.

              The transformer upgrade made the amp MUCH smoother, no need to clip the bright cap, the OT was added to the 1987x months after the PSK. This could be a long shot, but I thought the amp sounded much more like a REAL plexi.

              After I was done studying what was best for me using my friend's 1987x, I have asked to have all the mods done in a batch: PSK,JJs,OT and loop.

              It's hard to say that the amp sounds exactly the same, they would have to be at the same volume, but the PSK keeps the power tube distorsion as you lower the volume, thus making it different, am I making sense ?

              Comment


              • #22
                I see. When you Power Scale, you naturally tend to include power tube saturation in the mix even at lower volumes, but not so with quiet playing w/out the PSK, it's basically just preamp tube distortion.

                Ok, how about at somewhere like practice volume with a miked drummer, where the power section is somewhat cranked. Would the amp sound about the same or would it sound somewhat different...

                ... with
                and
                without Power Scaling? Say MV around 8 or so on both amp settings w/and w/o PSK.

                See, you and others have said that changing the transformer can and does make a sonic difference. Such a claim is well established, different transformers can make a significant difference. On the other hand, it's my understanding that Power Scaling changes what is going on with the (power or output) transformer.

                Some amp techs I've been chatting with online say that once you alter the B+ voltage (that's what a PSK alters), you are essentially changing the sonic character of the amp. It's no longer the same amp, at cranked or less than cranked levels. They are into making clones of the Marshall 18watt amp, and so I tend to suspect that they understand what it takes to remain faithful to the original sound. I think this is a suspicion of theirs as they have not tried power scaling (yet), although they seem very knowledgeable and skeptical.

                I've heard your sound samples and I've heard some others from that guy who helped develop the use of the drive compensation control as a post PIMV (post phase inverter master volume).

                Here's a link to a post you might be interested in.
                CLICK HERE for more on quiet cranked amp sound
                Hold on to your dreams

                Comment


                • #23
                  Originally posted by 1_Way

                  Here's a link to a post you might be interested in.
                  CLICK HERE for more on quiet cranked amp sound


                  You will find good info at the VA forum, especially from Marshall Maniac.

                  To me, if you attenuate to 90db, you should hear no tone alteration. At 90db your speakers will be pushed hard enough.

                  But remember, with no PSK and the volume at 8, it is SO loud that you cannot really tell what it sounds like unless you isolate the cab ! You can get permanent earing damage !

                  The PSK is more a power suply mod, the OT doesn't have to be modded. I might be wrong since I'm no techy !

                  Go check out thegearpage.net and do a search on the user "kevinoconnor", you will find good information there too.

                  E-

                  Comment


                  • #24
                    begin_etienne
                    Hey, it's been a while! Hope you are doing fine. Are you still living in the temporary hotel arrangement? And how's things with your most excellent power scaled amp?

                    I'm interested in a specific issue that maybe you can help me with. I'm wondering about your ability to dial in singing sustain from feedback, the sonic relationship between your speakers and the guitar's pickups. And can you do that at lower volumes.

                    I used to own a solid state amp, the Marshall Lead 12 and I could get that thing to feedback at just about any volume, pretty cool stuff, but it lacked bottom end. Some at another forum are trying to discourage me from getting the power scaling kit if I hope to get low volume sustaining feedback. Also, do you ever use a distortion pedal up front, some say that might help me get the low volume sustaining feedback effect.

                    What are your thoughts and suggestions?

                    Thanks!
                    Hold on to your dreams

                    Comment


                    • #25
                      Bump,,, anyone seen begin_ettienne?

                      begin_etienne
                      I sent you a pm, I'm hoping to hear from you about my last post.
                      Hold on to your dreams

                      Comment


                      • #26
                        If you want controlled sustain/feedback, read this:

                        http://www.sustainiac.com/model-b.htm

                        There is a forum member who bought one, and made a bunch of clips with it and a POD... unreal stuff! The forum member is iAnders I believe... do a search for "sustainiac".

                        Comment


                        • #27
                          Wow, that's nuts! I remember when I first heard about that unit, it must have been back in the 80's or so.

                          I was hot for it then, but never got one. I did not know that they still made that thing! Thanks for the link!

                          I wonder how much it runs...
                          Hold on to your dreams

                          Comment


                          • #28
                            Bump

                            Still looking for begin_etienne, anyone seen him?

                            The sustainiac is about $300 and requires some extensive cords and such. I'm leaning towards an amp and pickup approach instead.
                            Hold on to your dreams

                            Comment


                            • #29
                              Originally posted by 1_Way

                              The sustainiac is about $300 and requires some extensive cords and such.


                              You can try their "stealth" approach too:

                              http://www.sustainiac.com/stealth.htm
                              http://www.petersamplification.com

                              Comment



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