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Topic: 4 Ohms or 8 Ohms |
Larry Moore
From:
Hampton, Ga. USA
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Posted 10 Aug 2018 3:30 pm |
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How do you tell what the Ohms output of a amp is with a meter?
Larry |
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David Higginbotham
From:
Lake Charles, Louisiana, USA
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Posted 10 Aug 2018 3:57 pm
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| Put your dial to the ohm symbol and connect the electrodes. 4 will read anywhere from 3 to 5....8 ohm will read anywhere from 6 to 9. |
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Larry Moore
From:
Hampton, Ga. USA
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Posted 10 Aug 2018 4:31 pm
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| Do you mean with the wires not connected to the speaker? |
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David Higginbotham
From:
Lake Charles, Louisiana, USA
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Posted 10 Aug 2018 5:56 pm
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That's correct. Disconnect the speaker wires from the amp first.
Dave |
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Larry Moore
From:
Hampton, Ga. USA
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Posted 10 Aug 2018 7:24 pm
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Thanks David I thought so but was not sure.
Larry |
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Stephen Cowell
From:
Round Rock, Texas, USA
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Posted 10 Aug 2018 8:30 pm
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You cannot measure the ohms output of an amp with a meter. David probably thinks you're trying to measure the speaker's ohms.
You have to either look at the back of the amp, read the owners' manual, or otherwise find the information from a reliable source. One important source would be the original speaker installed... what ohms was it marked?
Chances are if you mention to us the make/model etc of the amp we'll know almost immediately what load it expects.
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David Higginbotham
From:
Lake Charles, Louisiana, USA
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Posted 10 Aug 2018 10:26 pm
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Stephen,
You are correct in my assumption that Larry was wanting to measure the ohms for 4 & 8 ohm speakers in an amp. Looking back on his question I may have been incorrect and your answer is spot on.
Larry, if this was your question please disregard my reply as I misunderstood. I can also interpret your question as asking what the power output would be using an 8 ohm vs a 4 ohm speaker. There's a formula that I'm sure Stephen can easily recite but it's a little more than half of what your power would be with a 4 ohm speaker. Sorry if I misunderstood what you were asking.
Dave |
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Tony Prior
From:
Charlotte NC
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Posted 11 Aug 2018 1:08 am
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good catch David !
_________________
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Pro Tools 12 on WIN 7 !
jobless- but not homeless- now retired 9 years
CURRENT MUSIC TRACKS AT > https://tprior2241.wixsite.com/website |
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Larry Moore
From:
Hampton, Ga. USA
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Posted 11 Aug 2018 5:15 am
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the amp is a Sho~Bud Christmas Tree.
The only ID # 1068 is stamped on the back of the Amp next to the on/off switch.
Larry |
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J Fletcher
From:
London,Ont,Canada
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Posted 11 Aug 2018 9:14 am
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| My Sho~Bud Xmas tree amp had an 8 ohm JBL installed. Pretty sure it was the original speaker. |
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Stephen Cowell
From:
Round Rock, Texas, USA
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ajm
From:
Los Angeles
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Posted 12 Aug 2018 11:18 am
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Stop.
First, amps do not output ohms. And in spite of what I have read numerous times in numerous places, pickups do not output ohms either.
Larry Moore: What are you trying to find out?
What are you trying to do?
We still really do not know.
Also........
Do not disconnect a speaker from the amp output with the amp powered up, ESPECIALLY with a tube amp.
Last edited by ajm on 12 Aug 2018 7:17 pm; edited 1 time in total |
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Larry Moore
From:
Hampton, Ga. USA
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Posted 12 Aug 2018 12:49 pm
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So am I to assume the Christmas Tree amps are all 8 Ohms
I have a JBL D-130 8 Ohms speaker.
It had a M-31 JBL 8 Ohms speaker when I bought it 2nd hand.
Someone told me it was suppose to have a D-130. at the time I did not know you could get a D-130 in 8 or 4 Ohms.
This is the question..
Which one is correct?
Larry |
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David Higginbotham
From:
Lake Charles, Louisiana, USA
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Posted 12 Aug 2018 1:11 pm
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Larry,
Since your inquiry has been somewhat vague and misunderstood by yours truly, I assume that you're actually trying to find out whether you can use an 8 ohm or 4 ohm speaker in your amp? Most amps will tolerate a 4 ohm speaker but some require an 8 ohm load minimum. The current solid state Boss Katana is an example of wanting to see a minimum 8 ohm load and the original Vibrosonic tube amps also are best with an 8 ohm load. This is also true with power amps in the bridged mode where you can only use an 8 ohm speaker.
Your particular amp will be fine with an 8 ohm speaker and in the case where it doesn't have the ohms posted on the magnet, the process I mentioned above will answer your question. Some speakers have been reconed and the magnet may have 8 ohm stamped but the cone was changed to 4 ohm and vice versa.
Disconnect the speaker from the amp and check the ohms with a meter. If it's in the 8 ohm range or even 16 ohm range then you will be just fine with your amp. If it reads 4 ohm range then it will overheat the amp and possibly cause damage to the amp and voice coil of the speaker. If you have a D-130-8 speaker you will be just fine. I don't remember the output (wattage) of these amps but it's less than 100 watts so the combination will work just fine.
Sometimes we're all guilty of looking to deep into a problem when the solution is quite simple. Hope this helps!
Dave  |
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Larry Moore
From:
Hampton, Ga. USA
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Posted 12 Aug 2018 1:36 pm
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David thanks for the help.
Im going to put the D-130-8 Ohms into the amp.
Someone also told me the M-31 is the same as a D-130 ??
Thanks from all that helped me through this mess.
Larry |
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J Fletcher
From:
London,Ont,Canada
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Posted 15 Aug 2018 5:18 am
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| I remember my Xmas tree amp had a JBL M31. I think that was stock , not a replacement. |
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