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ohms

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(@peaveywolfgang5150)
Estimable Member
Joined: 20 years ago
Posts: 128
Topic starter  

i never really understood any of this but can someone tell me what i should put the ohms at, i have a 2 speaker outputs, one speaker is said to have a 8 ohms, and the cab says 8ohms also, i have 16 8 or 4 ohms selection, which one do i put it on?


   
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(@kalle_in_sweden)
Prominent Member
Joined: 19 years ago
Posts: 779
 

Hi
A first question; Wich equipment has the 16 8 or 4 ohms selection possibility ?
If it is the speaker cabinet , you should use the 8 ohm setting.
If it is the amp, I would also say use the 8 ohm setting.
But first READ the amps MANUAL, it should be stated there

Tanglewood TW28STE (Shadow P7 EQ) acoustic
Yamaha RGX 320FZ electric guitar/Egnater Tweaker 15 amp.
Yamaha RBX 270 bass/Laney DB 150 amp.
http://www.soundclick.com/kalleinsweden


   
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(@peaveywolfgang5150)
Estimable Member
Joined: 20 years ago
Posts: 128
Topic starter  

the amp has the 4,8,16 setting, the amps speaker is rated 8 ohms, the cab is rated 8 ohms, they run at the same time


   
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(@sophisticated-beggar)
Active Member
Joined: 19 years ago
Posts: 12
 

the amp has the 4,8,16 setting, the amps speaker is rated 8 ohms, the cab is rated 8 ohms, they run at the same time

You have 8 ohm speakers. Put the switch in the '8 ohms' position.

Ohms are the measurement of resitance in DC electronics, but in AC it is impedance.

The switch you have on your amp allows you to use 4, 8 or 16 ohm speakers. Since yours is 8, simply set it to 8.

Most speakers are 8 ohms, occasionally 4.
16 and 32 ohm speakers are usually headphones.

Setting this incorrectly can seriously damage your amp and/or speakers.


   
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(@wes-inman)
Illustrious Member
Joined: 21 years ago
Posts: 5582
 

I am not sure I follow you.
i have a 2 speaker outputs, one speaker is said to have a 8 ohms, and the cab says 8ohms also

If you are running a single 8 ohm speaker AND an 8 ohm cab off your amp you should probably put that switch at 4 ohms.

Most amp's speaker outs are wired in parallel.

Two 8 ohm speakers or cabs in parallel is a 4 ohm load.

Two 8 ohm speakers or cabs in series is a 16 ohm load.

What make and model amp do you have? Is this a combo amp with one 8 ohms speaker?

Knowing your amp and exactly what you are powering with it will help us answer you properly.

If you know something better than Rock and Roll, I'd like to hear it - Jerry Lee Lewis


   
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(@slejhamer)
Famed Member
Joined: 20 years ago
Posts: 3221
 

Two 8 ohm speakers or cabs in series is a 16 ohm load.

As an aside, why would someone wire speakers in series? Would you only do that, for example, if you had two 8 ohm speakers (or cabs) to power, but your amp's minimum load rating was 16 ohms and so you need to increase the overall impedance? Any other reason? Just curious.

"Everybody got to elevate from the norm."


   
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(@wes-inman)
Illustrious Member
Joined: 21 years ago
Posts: 5582
 

slejhamer

I am no expert on this at all, but there are times when wiring speakers in series is beneficial.

Take for instance a 4 X 12 cab loaded with four 8 ohms speakers. In parallel this would be a 2 ohms load, lower than most amps can handle.

So often two 8 ohms speakers are connected in series for 16 ohms. The other two 8 ohms speakers are also connected in series for 16 ohms. But then the two seperate pairs of speakes are connected to each other in parallel for an 8 ohm load.

So this is how they get four 8 ohm speakers in a cab with 8 ohms total resistance.

And some amps operate at 16 ohms. My Marshall DSL401 operates at 16 ohms. It can run at 8 ohms total with an extension speaker or cab.

If you know something better than Rock and Roll, I'd like to hear it - Jerry Lee Lewis


   
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(@slejhamer)
Famed Member
Joined: 20 years ago
Posts: 3221
 

Gotcha; thanks Wes. :)

"Everybody got to elevate from the norm."


   
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(@peaveywolfgang5150)
Estimable Member
Joined: 20 years ago
Posts: 128
Topic starter  

im going to tag another question on this one, i love my ultra, and the reason i got it was becasue of the warm but heavy distortion sound i can get out of the thing, but there is a problem with the clean channel, i have the volume on 6 and the master volume on .8 and its really distorting the clean channel, i thought maybe it was the guitar but i tried another guitar same problem, its a really big problem for me even though i prob use the clean channel 25% of the time im playing. any ideas?


   
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(@kalle_in_sweden)
Prominent Member
Joined: 19 years ago
Posts: 779
 

As being electronic engineer I know a bit about amps and the output impedance.

Amps with tubs power amplifiers has normally a transformer in the output stage.
The output windings of that transformer is matched for given speaker impedance (ohms figure).
Some amplifiers could therefore have several selectable output windings to match different speaker ohm figures.

Amps with transistor power amplifiers has very low output impedance (<<< 1 ohm) and can drive load impedances ( speakers) from 2 ohms and upwards.
The lower ohm figure you have on the speaker the higher output power you get until the power amps current limiting circuitry sets in ( the lower ohm figure, the higher output current in the power amp).
A good transistor amplifier design should not be damaged by driving a too low load impedance , its should protect itself with current limiting and/or overheating protecting circuitry.

But, modern guitar transistor amps can have a power amp design that simulates the "high" output impedance of a tube amp and could also have selectable output ohm figures.

You should therefore always try to match the total load impedance ( of all connected speakers) to the recommended output impedance of the amp. It will give you the optimum output power and the best sound.

Tanglewood TW28STE (Shadow P7 EQ) acoustic
Yamaha RGX 320FZ electric guitar/Egnater Tweaker 15 amp.
Yamaha RBX 270 bass/Laney DB 150 amp.
http://www.soundclick.com/kalleinsweden


   
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