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amp hum after mod - help!

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  • #46
    Originally posted by gusfinley
    As far as chokes in the amp go - I was using the power supply desinger from dancanamps.com. I had it set up to a CL filter with a choke in place of where the resistor would be on a RC filter....

    I'll check the suggested websites for more info...

    Also, Do you where I can pick up a replacement 15mm dual ganged A200K pc mount pot from? Is there some place I can order marshall replacement parts from?

    thanks so much for all of your help, I've really enjoyed the discussion....


    You are most welcome, I have enjoyed it too. This is one link for trafo info-
    http://www.londonpower.com/hammond/matching.htm
    I would ask a local repair guy for the pot. If he does Marshalls maybe he has one. I know there are on-line parts places that offer special Marshall parts, try a search maybe?

    Comment


    • #47
      I found ONE place that stocks them and they are .95 each!! Sadly they require a $25 minimum order, so I am getting some parts for my new amp, too!!

      Comment


      • #48
        Originally posted by gusfinley
        I found ONE place that stocks them and they are .95 each!! Sadly they require a $25 minimum order, so I am getting some parts for my new amp, too!!


        That's an OK price. $25 is far too easy to spend now a days. So what brand of terminal strips do you use? The ones I get are made by Cinch. I like them because they have an upper and lower of holes for each spot. Ends up looking far better. My last amp was so crazy complicated I had to get a friend to make a super PCB. No problem as I never plan to mod it. At worst I will build a preamp to plug through the FX loop. I built a Bassman but added two levels of Dumble style OD and a whole pile of extras. Mang just thinking about the amp makes me feel like playing so we'll talk later

        Comment


        • #49
          Originally posted by guitarzan


          So what brand of terminal strips do you use? The ones I get are made by Cinch. I like them because they have an upper and lower of holes for each spot. Ends up looking far better.


          I haven't got any terminal strips yet, to tell ya the truth I don't even know what to look for!! I was thinking about some singal row barrier strips... could you post a link to a few good examples of terminal strips... I have seen the kind with the screw terminals - this would be nice for testing purposes.. then i have seen sme really thin ones.....

          Consequently I have also been looking at how to build the amp and test it first before commiting it to a chassis.. I went to the hardware store and found that the puchouts in electrical sockets are 7/8" so I could probally mount preamp tube sockets in them for the time being.. I also found some octal relay socket that have octal sockets and then screw terminals to the "pins" - it will be great to get it up and working before I throw it in a box... I saw some guy do this on his website although he did have to punch holes for the preamp tubes....

          I need to see if anyone in town will punch the chassis for me - I'm on a budget being a student and don't went to $pend lot$ of ca$h on punches - especially the non-round ones that run $200+!!!

          also what kind of wire with I need to hook this up - I know that I'll need stranded 600V, but some wire isn't rated - is there a safe gauge that will work in the same setting..

          once again thanks for all the help.....

          Comment


          • #50
            just got my new digital camera today...

            here a pic of the fried resistor....

            still reads 100 ohms, too!!

            Comment


            • #51
              here are some pics of the tip jacks / pin jacks that I installed to monitor the bias without having to take the amp apart...

              I think I'll put them in all my projects from now on - you just plug your leads right into them!!

              Comment


              • #52
                and the other

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                • #53
                  Originally posted by gusfinley


                  I haven't got any terminal strips yet, to tell ya the truth I don't even know what to look for!!
                  Look here-
                  http://www.cinch.com/view_item.cinch?item_id=98&section_id=28&sub_secti on_id=35&section_title=Barrier%20Blocks&sub_sectio n_title=Accessories%20-%20Lug-Type%20Terminal%20Strips

                  I was thinking about some singal row barrier strips... Like these-

                  http://www.cinch.com/view_product_line.cinch?id=28
                  could you post a link to a few good examples of terminal strips... I have seen the kind with the screw terminals - this would be nice for testing purposes.. Maybe but they are costly. I did it once for a Hiwatt clone, sure they worked great but almost broke the bank.

                  Consequently I have also been looking at how to build the amp and test it first before commiting it to a chassis.. I went to the hardware store and found that the puchouts in electrical sockets are 7/8" so I could probally mount preamp tube sockets in them for the time being..
                  You will prolly end up with a mess of wires. Just buy a chassis from Weber SVT, the rejects(minor flaws) for dirt cheap.Best to work with what you are going to ideally want. Any time working with make shift items is prolly time wasted

                  I also found some octal relay socket that have octal sockets and then screw terminals to the "pins" - it will be great to get it up and working before I throw it in a box... I saw some guy do this on his website although he did have to punch holes for the preamp tubes... IMO just get a hole saw. About $20for a good one, you need two at most. One for 9 pin miniatures, and one for Octal and big caps like the JJs

                  I need to see if anyone in town will punch the chassis for me - I'm on a budget being a student and don't went to $pend lot$ of ca$h on punches - especially the non-round ones that run $200+!!!
                  As above, should be no more that 20/each
                  also what kind of wire with I need to hook this up - I know that I'll need stranded 600V, but some wire isn't rated - is there a safe gauge that will work in the same setting.
                  Stranded??? Use solid because it stays in the shape you make it, is way easier to solder...The only stranded wire I use is 3 conductor double shielded for sensitive areas in th preamp. It is not the gauge as much as the insulator that is crucial for voltage. PVC is fine, Teflon is better, cloth looks nice. Use 20 gauge for the heaters and 22 @ 600V for everything else. Use the wire that comes with the trafos as much as you can in the power supply...

                  once again thanks for all the help.....

                  Just get the lug type terminal strips and some Solder Wick...
                  Have fun, always remember safety first.
                  RE Lee

                  Comment


                  • #54
                    Originally posted by gusfinley
                    just got my new digital camera today...

                    here a pic of the fried resistor....

                    still reads 100 ohms, too!!


                    Cool, if I were you I would redo the DSL stock just to get it working. Then think about making your own super amp. The DSL is not bad but you could do better if you took your time and did it right, without those tone sucking anode caps!

                    Comment


                    • #55
                      Thanks for the input on those anode caps - I wondered what all those extra caps were for, and I especially wondered why I could never get my amp to feedback!!

                      I've determined that I will also put in some headers were the caps go also, Then I can experiment with having them in/out and see what I like. I've been wanting to play with some good feedback for quite some time now!!

                      I'll be using this amp for recording in my apartment (yeah, I know not the best, but it does have a great tone after a few touchups) and the nieghbors have been very willing to deal with the noise becuase the say they enjoy hearing me play - but they might not like the feedack - so it would be handy to be able to put them back in...

                      This is turning into quite the good project!! And it will be very easy to swap caps / transitors with the headers I will install - and I could put it all back to stock by just putting the right value of caps back in and hotgluing them in place - no one would ever know the difference - well excpet for the whole I drilled in the front panel for the "right swtiches" better make those functional I guess....

                      seriously, Guitarzan, you have been a great help and I'm gathering some good info for my upcoming DSL401 website... I'll be sure to give you credit - although i am not sure how you would want that done.... (guitarzan from the HC boards)

                      Thanks again!!

                      Comment


                      • #56
                        Originally posted by gusfinley
                        Thanks for the input ...

                        Thanks again!!


                        You're welcome. I was suggesting you build your new amp without the tone sucking anode bypass caps. The DSL may need them to keep out noise for some reason. As long as you are careful it could not hurt to try without them. It will feedback easier without them but you may get some surprizing parasites... IMO if you want to experiment you should get started on your DIY and spend the extra effort on that. The DSL will always be limited to mods by the PCB. Nice to have good neighbors. One of the reasons I live in a house! Give credit to Robert E. Lee if you like. No real need, just remember tone is in your head and my opinions may differ from others. There is no perfect tone, it is a individual experience. Electrical Laws are another thing. Get an ARRL handbook for easy understanding & quick reference to those equations if required. The 2002 Ed. I have even has a chapter on the benifits of tubes and how to use them properly.

                        Comment


                        • #57
                          Yeah, I won't be putting anode caps in my DIY - its going to be based off a marshall JMP 1987 - except is gonna have A LOT of switches on it to make it really CUSTOM. I am currently working on a USA/UK switch, which is gonna take some crazy "trickery" to get to work - might have to consult a professor on this one... So far its gonna half to use a 5PDT switch!! and they don't make those in the ratings that tubes are going to need!!

                          What does ARRL stand for - something to do with ametuer radio I'd guess... I'll see if I can find that book, still waiting to hear back about "The ultimate tone" I ordered it over a week ago and have recieved nothing!!!

                          As far as wiring goes, you suggested not getting stranded wire - does this include the AC heater wires that will be twisted to reduce interference?

                          I still plan to mod my DSL while I am getting ready to build my DIY - at least I will be modding something thats sound I am familar with the see, how different compenents, etc effect the tone....

                          Comment


                          • #58
                            Originally posted by gusfinley
                            ...effect the tone....


                            I have no idea why you would need a 5P/2T just to switch to UK volts. Are you trying to re-invent the wheel? If you use the right power trafo, see here-http://www.hammondmfg.com/300series.htm
                            it will have the right windings so all you should need is a 2P/2T.
                            The components that effect tone are many. Pretty much everything in some way, from the layout to the type of Rs you use. The big contenders IMO are the size of blocking caps, higher values yeilding lower FQ roll off and the cathode bypass caps that boost the gain of different FQs. Yes the heater wires can be solid core. Those are usually thick twisted wires.
                            ARRL= American Radio Relay League. I have two copies, 1952 and 2002.

                            Comment


                            • #59
                              Originally posted by guitarzan


                              I have no idea why you would need a 5P/2T just to switch to UK volts. Are you trying to re-invent the wheel?


                              Yeah, I am probally trying to reinvent the wheel here in a way - the USA/UK isn't a voltage switch, its a preamp thing- I am also planning on putting a Vox/Marshall switch in there to see if I can get an AC30 kind of tone. Like I said - this amp is gonna be crazy and its gonna require a lot of planning for it to work right, but its gonna be sweet when it is done!!

                              Comment


                              • #60
                                Originally posted by gusfinley


                                Yeah, I am probally trying to reinvent the wheel here in a way - the USA/UK isn't a voltage switch, its a preamp thing- I am also planning on putting a Vox/Marshall switch in there to see if I can get an AC30 kind of tone. Like I said - this amp is gonna be crazy and its gonna require a lot of planning for it to work right, but its gonna be sweet when it is done!!


                                The biggest difference between Vox & Marshall tone IMO is brought about with Marshall using global feedback but Vox using no NFB, aka open loop. There are way more than 5 things I can think of that are also different; Tone stack, cathode Rs & bypass Cs, Blocking caps, phase inverter, master volume, topcut/presence...

                                Comment

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