First Amp Build Component Options

Discussion in 'Building the Classics' started by myself80, Apr 20, 2015.

  1. Guitar-Rocker

    Guitar-Rocker Well-Known Member

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    That drawing has a few errors. On a 8 pin rectifier pins 4 & 6 are the HT secondary, while pins 2 & 8 are the 5v source with pin 8 usually going to the standby switch.
     
  2. myself80

    myself80 Active Member

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    Yes, I got the 50 watt chassis from Valvestorm. I am going to do the build without the switchable rectifier first to make sure I get it right. I will add the switchable rectifier once I get it up and running. This is my first build.......less variables = better:). I am going with a chassis mount pre-amp filter cap as per the original I am trying to clone so, I do have to punch the hole for that one.
     
  3. myself80

    myself80 Active Member

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    edit: It looked to close but wrong to me when I found it. The simplicity of it made me look in to it. Being that the OP never followed up on the thread, I figured he gave up. I have been trying to use the wiring diagram from the Tube Depot JTM45 kit. The circuit is somewhat different from my '72, but it looks like I can incorporate it into my build. I will draw a wiring diagram that I think will work when I get to that point. I am not sure about a wire going to a filter cap for it. My build has the filter caps wired very differently, maybe I need another just for the rectifier?
     
    Last edited: May 21, 2015
  4. danman

    danman Active Member

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    I was asking about the chassis because I remember you saying that you had purchased the 50 watt chassis from Valvestorm. If you do want to add the tube rectifier option, you will need to get the chassis punched for the extra tube socket that you will need. It would be better to take care of this now while the chassis is empty.
     
  5. myself80

    myself80 Active Member

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    Agreed. I was thinking about relocating one of the filter caps to the underside of the chassis and then use the hole for the rectifier. I am not sure whether the hole will work for the rectifier socket (don't have it yet). I hope it works without alteration, but I will make it work either way:D. I am going to install the switch for the rectifier on the rear of the chassis now so all that is needed later is a soldering iron and screwdriver. I may install a second cap bracket underneath in case the rectifier ends up needing it's own filter cap. Better not to have to use any power tools on a finished amp I figure.
    Thanks! Have a great weekend.
     
  6. myself80

    myself80 Active Member

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    Finally got a 2nd package today from Triode with the OT, PT and Choke. They look good. If only I could get the rest of the order:scratch:. I worked on the chassis over the weekend. Got the hole for the laydown trans. filled in. Note: if any one else is thinking of this, use a TIG welder. I have a MIG and it's a bit hot for this fine work. Now I need to clean up and finish the the chassis to look good, which it will:D. Also cut the hole for the chassis mount pre-amp filter cap. After this I will start a build thread w/ pics (once I actually get all of my order delivered). Hopefully I will have the chassis finished and get the build going by next weekend.
     
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  7. myself80

    myself80 Active Member

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    I have a couple of these vintage Erie 500pf ceramic discs. Can these be used instead of the 500pf silver mica caps (I think) in the circuit? What would the difference be and would it affect the sound of the amp at all? I like vintage parts, thought it would be cool.
    Thanks for any opinions.
     

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  8. myself80

    myself80 Active Member

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  9. neikeel

    neikeel Well-Known Member

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    Those ceramic disc caps will be fine. Ceramics tend to add a bit more grit to the tone so in a rock amp are fine, not quite as smooth as silver mica but certainly more reliable than some modern silver micas that crap out prematurely.

    The filter caps are more worthy of discussion. I have no problem with F&Ts - typically germanic and efficient. I have used them in a number of amps (in fact as I type this my son is banging away on a DR103 with his bass in the annexe - sound great!). The amp medic cans are good (even if he is a bit OTT) they are the right size (c.f. ARS which are a bit skinny) and dimensions/spec correspond with LCR cans which for me are the best amp cans you can (well, could) buy. I have a few left but all my 50/50s and 16/32s have now gone:(

    If I were in the US I would probably go with them (postage less) but then I would have gone Marstran or Merren for the iron so why not go with the F&T?
     
  10. myself80

    myself80 Active Member

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    I think I will use those ceramics in the build then. Worst case I swap 'em out for the silver micas.

    I find it tough to drop $75.00 on 3 filter caps, but I am only building this amp once. I might go with these. He also says that they are preformed which will save me a step. I was just looking at ARS caps. Aside from being a bit thinner, they get good reviews and are less than half the price. Although if I have to form them before use, the lower price becomes less attractive. I know F&T's are fine to use (and I already have 3), but I like the matching dimensions of these to the original Daly style.

    So many choices!:D

    Thanks!
     
  11. danman

    danman Active Member

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    The forming process is not absolutely necessary, although I do it with my new builds. You can bet that Marshall or other big manufacturers are not forming any caps being used in the amps though. With the 50 watt it is incredibly easy. Just solder a 100k/2watt resistor across the standby switch and turn on the power switch. once the voltage across that resistor is below 5v, you are ready to go. You must perform this step without tubes and before your initial power up and testing phase. The ARS caps that Valvestorm sells have always worked great for me and he will form them before shipping if you ask.
     
  12. myself80

    myself80 Active Member

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    I am going with the ARS caps. If forming is that simple I will do it. I hear it takes about 4-24 hours to finish? I may as well learn these procedures while I am doing this build.

    I actually got the last of the parts from Triode today! It took almost a month, but it is all here. This weekend I will finish the chassis mods (hopefully) and start a real build thread.
     
  13. Micky

    Micky Well-Known Member VIP Member

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    If a cap doesn't come formed from the manufacturer then it is bad.
    End-users do not need to form caps...
     
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  14. myself80

    myself80 Active Member

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    Well, have not truly started the build yet:ugh:. Reality gets in the way, 2 jobs, leaky plumbing, etc. Anyway. here is the wiring diagram with the dual/selectable rectifier. Does anyone see a reason why this will not work? If it is good, do I need to twist the output lines of both rectifiers when they go to the switch?
    Thanks for any info. I should :)laugh2:) have time to finish the chassis this weekend and get going for real on this thing.
     

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  15. Gordon Thunderfuck

    Gordon Thunderfuck Active Member

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    Do you have a video or sound clip you could demonstrate both modes? I was thinking of doing the same Mod as well ass changing the bright filter caps from .022 to .0022 and making that switchable as well.
     
  16. Garrett

    Garrett Well-Known Member

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    On the last page of the assembly manual they had a few suggested mods. I completed;
    2. Change the value of the bright channel coupling cap (C4, between T12 and T13)

    6. Install a different master volume, PPIMV kit from Triode

    9. Link together the first gain stage cathodes

    Also changed R5 and R6 from 470kOhm to 100kOhm as suggested on the schematic for 2204 added gain.

    The coupling cap change did tighten up the bottom end a bit from the stock build.

    The shared/split change is a bit more subtle but you can tell the difference.

    The PPIMV works well, but it has to be turned up at least half way. Add an attenuator and you can get decent power tube distortion at much lower volume.

    The #4 mod is very tempting, maybe some day....

    I must say, when this amp is cranked plugged straight in it sounds great, pure Marshall sound, but very freakin' loud. It also is a great pedal platform as well. I can run a digitech hardwire tl-2 into the amp and get great early Metallica tones.

    For early rock and metal I run it SS rectified, split cathode, Marshall NFB. Very tight compared to the stock build (and tube rectified). But that is the beauty of this design, use the tube rectifier and shared cathode and NFB to taste and it gets nice and loose, a fuzz pedal becomes heavenly.

    Even though it's based on a Bassman circuit, the cleans are not as fat and warm as a Fender. A-B'ed them with a friends Bassman. But as they say, if you want Fender cleans...buy a Fender.

    I have the ability to do some simplistic recordings but don't have the skill level that so many of the other members of the forums posses. I'm afraid I wouldn't do the amp the justice it deserves.
     
  17. stringer

    stringer Member

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    Did this ever get finished...
    just wondering...
     
  18. ampmadscientist

    ampmadscientist Well-Known Member

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    Start the reactor... Free Mars!
    MMMMMMMM,

    I am not too crazy for the ARS caps.
    I tried some ---and was not thrilled....they are cheap...probably made in China.
    Besides that there is no spec sheet, and no life ratings for them...

    When there is no spec sheet, I am suspicious.

    I took out those ARS caps...and ordered something else.

    I think I will just go with F&T.

    I'm still going to use silver mica, but high grade ones like Cornell Dubilier.
    I don't believe that there is anything wrong w/ using silver mica caps.

    Resistors: I'm not using carbon resistors for anything. Too noisy.

    As far as amp kits: I'm using a steel chassis, aluminum has too many issues.
    But on a steel chassis: I'm hard soldering all the grounds to the chassis.

    One other source that might come in handy is "Just Radios."
    http://www.justradios.com/
     
  19. myself80

    myself80 Active Member

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    Yes, I did finally finish it about 2 years ago now. I am most happy with this build! :)
    Here is the link to the build thread:

    http://www.marshallforum.com/threads/1972-50-watt-clone-build.81682/

    I do not think I ever posted the final correct wiring/component layout. Some things changed along the way!

    Cheers!
     
  20. myself80

    myself80 Active Member

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    "I am not too crazy for the ARS caps.
    I tried some ---and was not thrilled....they are cheap...probably made in China.
    Besides that there is no spec sheet, and no life ratings for them..."

    Those are concerns i heard about before using them. I mainly used them at the time (my first build)
    because they were closer in size to the original daly's. The amp only gets a few hours a week of use.
    So far they are still o.k.. At least I have F&T's on the side should I need them.

    Are there any sound issues with them that you know of, or is it more of a matter of not trusting them?

    Cheers!
     

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