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Thread: b-52 at112 60 mod for el 34's

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    b-52 at112 60 mod for el 34's

    Hey, can one of you fellow tube ampers please help me to mod my b-52 at 112 60 to accept el 34's? I finally got a schematic for this amp and need a little guidance on which resistors to change. I love the sound of 34's and would love to make this happen...thanks 😎

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    Lifetime Member Enzo's Avatar
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    Hi.

    It would be helpful for us if you posted that schematic so we too could see the circuit.

    Converting any amp from 6L6 (presumably) to EL34 includes the following considerations:
    1. EL34 needs 1.5A for heater instead of 0.9A. SO a pair needs 1.2A more heater current from the power transformer. SO is your transformer able to do that?

    2. The EL34 does not have internal suppressor to cathode link, suppressor is on pin 1, which needs to be linked to pin 8. Are your sockets on a pc board or hard wired? If they used pin 1 as a tie point - as is often done in 6L6 amps - that will have to be rewired.

    3. Screen grid resistors would want to be 1K 5w, the 6L6 probably has smaller resistors there.

    4. The EL34 probably wants lower bias voltage. If the 6L6s are running at -55v say, the EL34s will want more like -42v. SO your bias needs to be adjustable with range to cover that need.

    Cover those things before worrying further.

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    Hey enzo...i appreciate your reply. I have not been on a forum before...can you tell me how to go about posting that schematic with my post/ question...i apologize for being a dumbass..,��

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    Lifetime Member Enzo's Avatar
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    CLick reply.

    To post attachments like schematics or photos, click Go Advanced, lower right. That just opens the full featured posting window instead of the quickie one.

    Scroll down to see Additional Options, wherein find Attachments, and click the Manage button.

    That opens a new little box where you enter the link. If your schematic is from some other web site, enter the URL for it in the box Upload from Website. If it is stored on your computer, then click a Choose File box and you will be in a file listing you can select from your stuff.

    My example is something on my hard drive. I found it in the listing, highlighted it with my mouse and hit enter. Now that file name shows in the box nect to Choose. Now I click Upload just under there, and off it goes.

    Voila:
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	aaaa thermal fuse.jpg 
Views:	64 
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ID:	43618  

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    Enzo...man , i cant download from me phone...when im lookin at the schematic...it appeats pins 1and 8 are connected. Is there any way you can check a schematic for this amp from your end....please��

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