1947 br6 amp project.

Discussion in 'Amp Central Station' started by jimi6string, Mar 10, 2014.

  1. jimi6string

    jimi6string TDPRI Member

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    Hello there,

    I don't have pictures yet but I can get some soon. Due to outrageous estimates, I've decided to fix/modify my amp on my own. I was wondering if anyone can help with some info?? I'm not trying to sell this amp it was a gift from my grandpa and i want to keep it in the family. When I received this Gibson br-6 I had no idea what I had, and being a dumb teenager at the time ripped out the broken/ripped speaker and planned on fixing it later. Now 12 years later I have enough solder experience/balls to take on this project.

    Question: What output transformer would work best with this amp if i wanted to put a modern 10" jensen speaker in it???

    I've heard that some of the fender ot's work great. I also wanted to see if i can get a little guidance on this type of upgrade as well?? That is if anyone is up for it.

    Thank you for any input!!! jimi6string
     
  2. printer2

    printer2 Poster Extraordinaire

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    What is wrong with the old transformer?
     
  3. eugenedunn

    eugenedunn Friend of Leo's

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    Hey! Welcome to the Forum! Here's some advice to get you in the right ballpark possibly, since these amps are quite old and documentation on them is sketchy, at best.

    I don't know much about the BR 6, but I did something similar to what you're thinking about attempting on my 1948 BR 9.

    But first, you need to find a schematic, post some photos of your amp.....then read this thread, which will get you started with ideas:

    http://www.tdpri.com/forum/amp-central-station/181137-gibson-br-9-amp-restore-questions.html
     
  4. jimi6string

    jimi6string TDPRI Member

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    I don't have the old transformer. I was a dumb kid that ripped out the old ripped speaker and field coil.
     
  5. jimi6string

    jimi6string TDPRI Member

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    Yeah I'm behind on the time and i don't have a camera right now. But i will try and get some pic asap. I do know that the main capacitor needs to be replaced because it is busted......let alone way over due!!! I'm just a guitar player that wants something kinda unique and modified. I can't afford to have it restored.
     
  6. Mike Simpson

    Mike Simpson Doctor of Teleocity

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    It may help if you would post some pictures of the inside of the amp and the bottom of the chassis then the amp guru's could see what you currently have.
     
  7. jimi6string

    jimi6string TDPRI Member

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    Working on it.. I'm really excited about this thing. I know it's gonna take some time and patience though.
     
  8. jimi6string

    jimi6string TDPRI Member

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    http://www.tdpri.com/telephoto/showphoto.php/photo/30882/cat/500/ppuser/109245

    Hope these pics help you help me hahaha. I really want to get this thing going and sounding as good as we can get it, for my budget that is. In ADVANCE.... Thank you for any input and knowledge. I really want to learn this stuff so I don't have to pay for labor. The soldering/testing is the fun part. Why would I want someone else to do that???
     
  9. eugenedunn

    eugenedunn Friend of Leo's

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    Looks like you have the 2-input, 1 volume knob model. Here's the schematic. Can you verify the tubes are as listed here?
     

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  10. printer2

    printer2 Poster Extraordinaire

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    Not the only schematic, Gibson is known for making changes, this version of the Br-6 has a 6SJ7 on the input.

    http://www.webphix.com/schematic heaven/www.schematicheaven.com/gibsonamps/br6f.pdf

    Which brings up Schematicheaven hosting schematics, seems it is going away at the end of the month so if you need a schematic get it now.
     
  11. printer2

    printer2 Poster Extraordinaire

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  12. jimi6string

    jimi6string TDPRI Member

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    Thanks foe the info guys. I will read up on this some more. Is there any difference in the br-6 and the br-6f schematic other than the three inputs???
     
  13. Wally

    Wally Telefied Ad Free Member

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    Welcoem, jimi6string. Your last question gave me a chuckle...thanks. Gibson was notorious for changing amp circuits on the fly, so one has to look at what one has and compare it to various schematics to get a grip on what the amp actually is....and often the reality will not match the schematic. I have 3 Gibson/Epi models of the same amp made within weeks of each other and none of the three left the factory being exactly what the other two were!!! And....none of them adhered strictly to the schematic...adn this was in 1964! You would have thought that they would have settled down by then, right? LOL
    FWIW, that amp is probably a grid leak bias input amp, which is not a good thing if one wants to run pedals. IIRC< one can change the input resistance to make that circuit more pedal friendly. good luck with it.
     
  14. eugenedunn

    eugenedunn Friend of Leo's

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    And let's not forget the Gibson and evil twin sister Kalamazoo amp lines from the 60's! Wow, talk about deviations........
     
  15. jimi6string

    jimi6string TDPRI Member

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    Wow!!! I have a lot to learn. I used to work at a antenna shop for ham radios and got my soldering skills there along with some testing. I'm still a rookie i guess. I have wired up guitars and mic cables but, An AMP!!! I want to learn it though. I feel a lot of the techs in my area are ripping people off. Every time I try to talk to a tech they seem really shady. I tried to talk to a tech the other day and he just turned around and walked away!!! They don't want people to know what they are doing so they can rake in the dough. I just can't trust them anymore. Last time i took in an amp for a 3 prong cord install, when I got the amp back, the price was more than the estimate.... he gave me an old capacitor and said the amp is ready. I got home and played it for 20mins and the amp stops working????? I don't get it. I am going to replace the rectifier tube to see it that fixes it. The existing one looks very dim.


    Sorry for the ramble. I'm so glad I found this page. Back to the EVIL KALAMAZOO!!! So a new cap job, output transformer with a choke? or resistor? I need to get new tubes, speaker , and figure out where all these old ot wires go. My tube amp book is coming in soon!!!!!

    Step one: Always discharge your filter caps!!!!! Are there any good replacement multi caps out the like this one?
     
  16. Wally

    Wally Telefied Ad Free Member

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    jimi, I grew up around mechanics back in the '60's. BAck then they kept a sign on the wall...
    Labor charges...
    $10 per hour
    $50 per hour if you ask questions
    $100 per hour if you want to watch.

    Have you ever offerred to pay someone for some instruction? I woudl never expe t someoneto spend valuable work time trying to teach me something that I do for a living and into which I have put countless hours and dollars into while learning.
    There are only two ways to learn....working with someone who can teach you or by reading, studying and doing the work. Both of those methods have cost me money.

    WIth regards to the amp that got a 3-prong and one cap.....IF someone brought in an old amp that had never been serviced but all they wanted was a grounded power cord, I would turn down the 'opportunity' to work on that amp with those restrictions. Why? Because I know that that power cable can only lead to a situation where the owner of the amp will not be happy...because the amp is very like to work only for a short time...because it needs much more work than that 1) to work for any lenghth of time and 2) to sound as it should it needs fresh electrolytics. I learned this both by reading/studying and through experience. This tech with whom you are unhappy left himself open to your 'questioning' the abilities in his work. Perhaps his lack of experience with old amps lead him to try to do that limited work on an old amp....and that was his first mistake.
    IF someone demanded that such a half-stepping approach to amp work be taken, I would explain to the customer that the work would come not only without any guarantees but also with a warning that the amp's major components were being put into jeopardy due to the weakness of old electrolytics......and that I--the tech---would not be responsible for any failures that that amp might suffer. This would be in writing on the work order, also....singed by both parties. I like to eliminate the possiblitity of any misunderstanding. Both parties should know upfront what is to be expected at the end of the deal.

    Good luck with the amp work.
     
  17. Prairie Dawg

    Prairie Dawg Tele-Meister

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    No, they don't want to set you up in business by giving you their trade secrets, because it's how they put food on the table and pay their bills.
     
  18. eugenedunn

    eugenedunn Friend of Leo's

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    Go back and read that thread I linked at the beginning of this thread....... You are going end up doing pretty much what I did. Compare the BR9 schematic to the BR6 schematic and see if you can use the same type of parts list. So yeah, get a choke. Get the Weber Sig S Ceramic speaker for more headroom. The Weber Sig S Alnico has a deeper magnet assembly and may have clearance problems inside your amp's cabinet. Those are my caveats. Rock on, and keep one hand in yer pocket. (^_-)
     
  19. jimi6string

    jimi6string TDPRI Member

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    I'm sorry about the tech rant. I know there is a lot of very good techs out there. I'm a low voltage tech and to all my customers, i try to be as up front as possible as be honest with them. I look at them as a person not a dollar bill. I think everyone should have that sign wally lol!!!! Well it was nice chating with you guys. It's gonna take me a while to get everything together. I will keep this post up to date with the project. Will look at the br9 post again as well. Again thank you for all the info. and sorry for lashing out at local techs. Have a good evening.
     
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