Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TIMBO on February 05, 2012, 12:07:44 am
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Hi Guy's. Not sure what tabs to hookup the ECL84s to for a 8 and 4 ohm speaker, the only info i got is 15k:8ohm
http://www.hammondmfg.com/125.htm (http://www.hammondmfg.com/125.htm)
I usually have 8 and 4ohm speaker connections in my builds, Also is the size of the speakers a problem to the small tubes as my speaker box has two 12" Mod 50's wired to 4 ohms. Thanks
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15000 : 4ohm use 1 & 3
12800 : 8ohm is close enough to 15000 so use 4 & 6
--DL
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Thanks DL :icon_biggrin:
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Thanks guys,got that part sorted but if i was to have only one 4ohm speaker jack that would be easy but if i have 1x 4ohm and 1x 8ohm jack do i need to ground tag 4 as i have grounded tag 1 as you would. :help: Any problems on the size of the speakers for these little TUBES ??? Thanks
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Any problems on the size of the speakers for these little TUBES ???
Not sure that I understand the question, but I run my SoLow Watt into one 8 ohm Cannibis Rex (Emminence speaker).
With respect, Tubenit
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if i have 1x 4ohm and 1x 8ohm jack do i need to ground tag 4 as i have grounded tag 1 as you would.
no, you use one pair or the other pair exclusively - not both, unless you use a switch - simplest method would use DPDT sw - a 2A toggle or rotary will work fine. you need only one jack. still two holes in chassis though. use a 4TDP rotary and wire up 2, 4, 8, & 15ohm.
4ohm
1 x x 3
| |
spk (-) x x spk (+)
4 x x 6
8ohm
--DL
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Thanks DL, Tubenit, what i mean is does the actual size (8",10",12",15")speaker make the tubes work any harder to push the cone. Thanks
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Thanks DL, Tubenit, what i mean is does the actual size (8",10",12",15")speaker make the tubes work any harder to push the cone. Thanks
don't worry about that.
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> make the tubes work any harder
Cathode-bias amps, the tubes "work harder" when _silent_. They take-in all the power they will ever put out, waste most of it, but divert some power to the load and run cooler.
> does the actual size
For a given acoustic level in the room, more/bigger speakers need _less_ power from the amp. Take a flea-watt amp. Connect it to a Full Stack (eight 10"s) and to a car door speaker. You can annoy the whole neighborhood with the Stack. Doing the same with the car speaker needs 10+ times the power.
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Thanks guys :icon_biggrin: