| Ohms and speaker cabinets/amps [message #3752] |
Sun, 22 February 2004 17:46  |
woody96
Messages: 107
Registered: May 2001
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Senior Member |
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Haven't posted here in a while...great bunch of folks this Kustom crowd!!! I have a question regarding speaker cabinet ohms and amps.....I have a vintage 1963 Gibson Atlas amp (approx. 50 watts) pushing an original speaker cabinet with a CTS 16 ohm 15" speaker.....if I change cabinets (to either Kustom 2x12 or 2x15 for ex.), what do I need to watch out for as far as speaker cabinet OHMS and this amp? OK to go with a 4ohm cabinet, 8 ohm cabinet? Can I re-wire the Kustom cabinet (series or parallel) to make it safe to use with this old Gibson head?? The original schematic for this amp doesn't state ohm outtage...all I know is it is paired with it's original cabinet with 16ohm 15" speaker....By the way, this original amp has 2 vintage 6l6 wgb's and three 12ax7's.....AWESOME tone! THANKS!!!
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| Re: Ohms and speaker cabinets/amps [message #3763 is a reply to message #3758] |
Mon, 23 February 2004 16:51  |
C4ster
Messages: 686
Registered: June 2001
Location: Mukwonago, WI (Milwaukee...
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Senior Member |
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Actually, Tube amps are less prone to shorting problems than solid state amps. The output transformer is the actual load for the output tubes. But because the transformer is inductive by nature, a high voltage will appear across the tubes if the output is opened to the speaker. For that reason, amps like Fender will have a shorting jack for the output so in case the speakers are not attached, the output is shorted to reduce the chance of blowing the tubes. The rule is: don't short a solid state amp and don't open a tube amp.
Conrad
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| Re: Ohms and speaker cabinets/amps [message #3769 is a reply to message #3767] |
Tue, 24 February 2004 09:49 |
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OK, I am not an electronic expert regarding ohms and such, but are you all pretty much agreeing that as long as I don't punch it up....I can use this amp (originally designed to work with a 16 ohm speaker cabinet) with for ex., a 4 ohm load cabinet, or an 8 ohm cabinet? If not, can I not just run 2 8ohm speakers in series to bring the total ohm load to 16, therefore matching to this old Gibson amp??
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| Re: Ohms and speaker cabinets/amps [message #3771 is a reply to message #3769] |
Tue, 24 February 2004 19:54 |
QModer
Messages: 413
Registered: June 2003
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Senior Member |
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I would just plan on bringing it up to what the amp wants to see as it sounds like you intend to be using it more. Since its easy to wire those eight ohm speakers why not do it and have a longer lived amp. The Bassman head I smoked was never run over four or ten oclock on the volume depending on what term you prefer to use hands on the clock or numbers on the volume dial. I don't think thats overdriving it too much. I have two four ohm Bassman cabs but I always just run one now to be on the safe side. Its so loud with that one I can't see me having to run the both of them. They do look cool all stacked up there. What happened was the transformer burn out. I could probably get away with dropping the impedance a time or two but I see no real reason to risk another melt down. But again its your amp so you are the ultimate judge here if you can afford a new transformer or not and don't mind running the risk of damages. I just don't think its worth as it does not double the volume at all to run under the stated amps impedance. At best you are only gonna get more disperision not doubled volume. But again I always like to er on the safe side. No offense to anyone who has done this and never had a problem though and I'm sure there are some who have gotten away with it. But the designers would not specify the impedance for no reason.
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| Re: Ohms and speaker cabinets/amps [message #3772 is a reply to message #3771] |
Tue, 24 February 2004 21:46 |
ET
Messages: 146
Registered: October 2000
Location: Charlotte NC
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Senior Member |
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I have a 4 ohm kustom 4x12 cab (old one with the ports..not the new crap).. I wanted to run it with my 64 showman head and just couldn't trust the 4 ohm load on the ol gal so I rewired the cab which put it up to 16 ohms...not what I wanted to get, but actually it tightened up the tone of the cab and the showman is still plenty bold and loud.. Irun the amp on 8.5 and get plenty of voltage signal into it as I use a pedal board with a parametric eq that is boosting the signal by a couple more db on top of my overdrive pedals, etc... I've not had a problem with the fender at the 16 ohms and am thrilled with the resulting "feel" of the cab...I'd have to agree that there's no technical reason why your Gibby can't talk to your cab as is, but I'd recommend taking the ol gals age into consideration and showing her some ohmage love...got to 16.
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