Amp Building Notes for a Friend - Feedback Appreciated, Thanks

Discussion in 'Shock Brother's DIY Amps' started by mabinogeon, Nov 18, 2019.

  1. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Hi all,

    I cross-posted this over on TGP, but I just discovered this fine website and thought I'd post here as well. I'm not sure how much overlap there is between memberships here and there. Apologies for such a long first post.

    A good friend of mine would like to try his hand at building an amp. Specifically, a 5F2A Tweed Princeton Weber kit. He’s a responsible adult and more than capable.

    He asked me a few preliminary questions, and I told him I’d write up a few notes about my observations, opinions, and (limited) experience on amp building and repairing. Much to my chagrin, it snowballed into a 35-page treatise. I am kind of embarrassed about that, but it does use a large typeface and includes many large pictures. It is not a how-to manual, nor an in-depth explanation of how amps work. I am also just starting a 5F2A build, so I was happy to collect my thoughts. And I have built a Weber kit, so I included notes about that.

    Long story short, I’d like to put a link to the PDF here and ask that if anyone is interested and has some spare time, they give it a quick read-through just to ensure I don’t have any outright falsehoods in there before I send it along to him. Or maybe anything I left out that really should be in there - I still have much to learn (you'll notice I'm still a little hazy on transformers).

    He and I are both Tolkien nerds, so there may be an occasional Tolkien reference. Sorry.

    I took all the pictures. I think this little project cost me $30 in shipping charges alone... o_O

    No hard feelings if you'd rather not read it, I get that we're all busy.

    I’m not sure what the TDPRI policy is on sharing PDFs, but here’s a link:

    https://drive.google.com/file/d/1_t_KJEOxSNNhyHWRXaVZ8HYpNnqTq69B/view?usp=sharing

    If that’s breaking protocol (or poor internet form), I am happy to remove it.

    PM me comments, or post ‘em here for discussion – just don’t be too hard on me…! :D

    Thank you very much for your time.
     
    Last edited: Nov 18, 2019
  2. muchxs

    muchxs Doctor of Teleocity

    Posts:
    11,893
    Joined:
    Aug 14, 2004
    Location:
    New England
    Overall a solid piece of technical writing with a few omissions. You should hike over to your local quick printer and print a bunch of copies. Have 'em GBC (comb) bound. There's your book! Sell it. It's worth ten bucks a pop on eBay.

    You could sell it as a data file. I'm Old School. I like books.

    Omissions:

    Page numbers.

    Frequent reference to Weber kits can be consolidated in to one general statement. Start with a Mojotone kit. I used to use Weber's chassis products and load 'em with my own parts kit. Their stainless steel chassis products were superior in many ways to the ubiquitous chromed steel "tweed" style chassis. The offshore chassis products look like they were "polished" with a belt sander while Mojotone's EPA approved chrome exhibits "nickel flash" and comes off in sheets if you try to drill though it.

    Ted Junior (Weber VST) first omitted the spotwelds on the chassis ends. I was told future batches would again be spotwelded. Future batches not only weren't welded, their jobber omitted the tabs negating any possibility of having them welded. I had considered buying batches and sending them over to our local aerospace fabrication shop. I'm fortunate to have various industrial resources humming away literally next door. Well... two doors down. Close enough!

    I'm tempted to do the legwork and offer my own high quality chassis products. If the money were there as per the tube hi fi market... but it isn't. Weber correctly identified the race to the bottom. It's super easy to comparison shop by price on the internet, not so easy to shop for quality. Even in industry "quality" has been subverted to mean cutting cost.

    If you want the high priced spread you need to pay for the high priced spread.
     
    King Fan, D'tar and mabinogeon like this.
  3. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Thank you very much for taking the time to read through that, and for your detailed response.

    I actually wrote each section separately in Word, converted each section to a PDF, and combined the PDFs into one with PDF-Redirect. I haven't figured out how to add page numbers to the PDF, so I may have to combine all the Word files into one and number them that way. There has to be an easier way... But I agree that they should be there.

    I have never used a Mojotone kit, so I didn't feel it was my place to compare them - but I will work in a reference based on your recommendation.

    Now that you mention it, I remember running a bead of clear silicone up the open seams in my Weber chassis to try to supress vibration noise - I noticed they weren't welded. I wonder how the Zach Hunter 6G2 chassis I just ordered on eBay will arrive... Might have to break out the welder to tack the corners.
     
  4. muchxs

    muchxs Doctor of Teleocity

    Posts:
    11,893
    Joined:
    Aug 14, 2004
    Location:
    New England
    Zach's chassis products aren't welded, either. It's less critical in a '60s style chassis. The chassis straps bear the weight of the transformers and everything else. Silicone in the corners damps vibration.

    I prefer welds when I can get 'em.
     
    King Fan and mabinogeon like this.
  5. mjcyates

    mjcyates Tele-Meister

    Age:
    55
    Posts:
    235
    Joined:
    May 4, 2010
    Location:
    louisville ky
    Thanks for putting that together! I have saved it for future reference. Very informative.
     
    mabinogeon likes this.
  6. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Thank you for taking the time to read it, and for your kind words.
     
  7. D'tar

    D'tar Friend of Leo's

    Posts:
    2,295
    Joined:
    Jan 11, 2013
    Location:
    WNY
    "A few notes" LOL:cool:

    Saved for casual reading at a later date!

    Welcome to the forum and thanks. Great first post and contribution.
     
    mabinogeon likes this.
  8. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Thanks much!
     
  9. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    KPAE likes this.
  10. Paul-T

    Paul-T Tele-Meister

    Posts:
    243
    Joined:
    Nov 23, 2018
    Location:
    London
    I enjoyed it. Very nicely spelt and punctuated too.

    At some point, if you want a comprehensive document, my take would be that exploring different transformers and issues around them, notably B+ voltages, might be even more helpful than different capacitor brands. There's a lot of good debate on these pages about voltages, and the impact it has, plus Classic Tone, for example, do a wide range of OT - even for something simple like a Champ, there are regular ones, beefed up ones, and even tiny vintage style ones. I think they're all really worth discussing given you're so near to a comprehensive document. But good work, sir!
     
    mabinogeon likes this.
  11. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Thank you very much for your time and your input.

    I agree that my transformer section is lacking - I definitely need to read up on those.

    I see that ClassicTone has a 5W and a 15W OT for the 5F2A Tweed Princeton - I'm building mine in a large chassis and wondering if I could use both transformers, and make the switchable, since there is room.
     
  12. DavidP

    DavidP Friend of Leo's

    Posts:
    2,514
    Joined:
    Mar 16, 2003
    Location:
    Vancouver, BC
    Wish I had a friend like you when I started building amps nearly 20 years ago!
     
    mabinogeon likes this.
  13. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Thank you for the kind words.
     
  14. King Fan

    King Fan Friend of Leo's

    Posts:
    4,259
    Joined:
    Jan 1, 2013
    Location:
    Salt Lake City
    Welcome to the forum. Based on your "Notes", you'll fit right in -- fun style, good sense of humor, willing to do empirical tests and wide research. Not to mention sharing your own preferences, experiences, choices, and (let's be fair) prejudices. Yep, for sure you're one of us!

    I sat down to write you a long list of suggestions, but after a while I decided your hard work deserved, how do you say, less? :)

    Every time we see 'first build questions' here, we gotta wonder why there isn't a concise, unified, respected, general guide. But I suspect there's a reason we don't have one. We're hobbyists; professional accuracy, concision, priority, and summary are not in our nature.

    Your letter to your friend is rich with charming, thoughtful personal choices, opinions, experiences, and varied but selected facts. Fun read. Did I agree with a lot of it? Well...

    Not a criticism; I think those notes will serve your friend well, and even more, I bet you'll find them a nice record of your amp building and research journey so far.
     
    mabinogeon and Paul-T like this.
  15. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Fortunately I have no issues radically altering my beliefs at will, so my prejudices could be different next week :D

    Don't be bashful about sharing - I am learning every day and wouldn't want to miss an opportunity to pick something up. I am always open to suggestions. When I started writing, it was just a few notes about tools and my experience with a Weber kit. As it snowballed into what it is now, I decided it would be a good idea to ask for some outside input in case I was way off base on anything. Had I set out knowing I might present it to a large audience of strangers on the internet, I probably would have approached it differently and written it a bit more professionally.

    I know what I know and nothing more, right? I don't claim to be an authority on anything... Except to my kiddos - they think I'm an authority on everything. For now. They're 5 and 8 and I'm sure their opinion of me will change as they get older! :eek:

    I would genuinely like to hear your feedback. When and if you have time, that is. I get that it's a big time commitment.

    Thank you for your time and for the warm welcome.
     
    Last edited: Nov 19, 2019
  16. muchxs

    muchxs Doctor of Teleocity

    Posts:
    11,893
    Joined:
    Aug 14, 2004
    Location:
    New England
    I'm not sure what the time limit is but beyond a certain point your posts are carved in stone so to speak. The option to edit is removed.

    I wish I had half an hour to correct spelling and grammar.

    Lotts guys try to do everything and make it all switchable. I like to arrive at a near optimum combination and hardwire it.

    I diligently avoid setups that are hot switched or may have configurations that unload the PA.

    Build a 5F2 with the 5 watt OT this time and 15 watts next time or the other way around.

    There's not much to lose by using premium transformers aside from a few dollars.
     
    mabinogeon and Mr Ridesglide like this.
  17. muchxs

    muchxs Doctor of Teleocity

    Posts:
    11,893
    Joined:
    Aug 14, 2004
    Location:
    New England
    Maybe devote a page to the (not so) intangibles?

    The short dissertation on pilot lights is spot on. My measure of a good kit vs. not so much is literally the pilot light. Or maybe the pilot light and the knobs.

    There were "metric" pilot lights that looked just like the good old Drake Industries pilot lights that Fender used. Aeronautical Electric Company beat the imports by bringing us U.S. made quality at a reasonable price.

    If you're into vintage electronics you will come across Dial pilot lights. Dial parts and Drake parts are interchangeable as are the Aeronautical Electric Company Chicago reproductions.

    We are musicians as well as technicians. How something feels is almost as important as how well it works. While quality feel in an amplifier is a little less tangible than quality feel in a guitar it's still there.

    The Aeronautical Electric pilot light is analogous to a Patent Pending bridge plate in a Telecaster.

    Real bakelite Heathkit knobs make the whole more than the sum of its parts.

    Switchcraft jacks and a Buss or Littlefuse fuse holder are visible parts that add to the quality feel.
     
    mabinogeon and D'tar like this.
  18. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    Good point. The last one I built has a couple switchable options and do I ever use them? Nope.

    Also a good point. I'm building this particular amp as small, around the house amp - so the 5W really is the most logical way to go.
     
  19. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
    I'll have to send him a monthly supplemental :lol: "This month's topic: Steel Vs. Aluminum Chassis" "Next Month: Cotton Vs. Linen Tweed" "Special Report on Boiled Linseed Oil, Shellac, and Polyurethane and their Effects on Pine Cabinet Resonance"

    Nah, I don't want to lose his friendship.

    Couldn't agree more. I am definitely a function-over-form person (hence the label-maker labels rather than custom faceplates), but high-quality components absolutely make or break the design. There is a certain beauty to a part that marries function with aesthetics and longevity. I don't even know how to properly articulate the sentiment. Some things just look cheap and it ruins the design. (I'm looking at you, crappy plastic pilot light holders).

    Thanks again for all your input.
     
    Last edited: Nov 19, 2019
  20. mabinogeon

    mabinogeon TDPRI Member Silver Supporter

    Posts:
    65
    Joined:
    Nov 16, 2019
    Location:
    Upper Michigan
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.