ohms

1166 Views 6 Replies 4 Participants Last post by wallie!, Dec 22, 2005

wallie!

Discussion Starter · Dec 21, 2005

I get my JSX head for Xmas and I was wondering what do the ohms switches do?

The head can either be 4,8, or 16 ohms mono, or 8 stereo or something.

It says when it does this the tubes go to 6l6's or something.

Does this mean if i lower the ohms the amp runs at a lower wattage ?

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Ant1981

· #2 · Dec 21, 2005

The Ohms switch is for matching different speaker cabinet combinations to ensure the power output is matched with the speakers, as speakers are in a way a load with reistance to the amps power. For example, a 2 x 12" cabinet will be 8ohms, 4 x 12" is 16ohms, two 4 x 12's will produce an 8 ohm load, two 2 x 12's is 4ohms. Thats a simple way to explain this without going into ohms law and getting too technical!

I hope this helps. Let me know how you get on with the Amp.

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wallie!

Discussion Starter · #3 · Dec 21, 2005

ah k

Also i read the amp specs again and it means the EL34's can be replaced with the 6L6EC's or whatever their names are

Cool

Amp arrives friday, i get it on xmas, cant wait

My teacher who organised it is a top bloke

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Ant1981

· #4 · Dec 21, 2005

Cool, I'm thinking of getting a Marshall TSL100 so that I can channel switch clean and overdrive keeping that vavle tone, the tone is lost with a distortion/overdrive pedal. But I'm interested to know what the JSX sounds like.

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rgr

· #5 · Dec 21, 2005

1st, the ohms switch has nothing to do with the type of tubes, there is another switch for 6L6 or EL34 tubes, this needs to be set to the type you are using.

Ant1981 said:
The Ohms switch is for matching different speaker cabinet combinations to ensure the power output is matched with the speakers,

Totally correct.

Ant1981 said:
For example, a 2 x 12" cabinet will be 8ohms, 4 x 12" is 16ohms, two 4 x 12's will produce an 8 ohm load, two 2 x 12's is 4ohms.

Only if the 2-12 has 16 ohm speakers wired in parallel and the 4-12 has 16 ohm speakers wired in series/parallel. Too many assumtions here, there are 4, 8, and 16 ohm 2-12s as well as 4-12s, it depends on the speakers and how they are wired. Better to just leave it at you set the ohms to match a single cabinet. If you are using 2 cabinets, 2X 8 ohm cabinets in parallel (which is the standard way they are hooked up) is a 4 ohm load, 2X 16 ohm cabs are an 8 ohm load. Can't use 2X 4 ohm cabinets unless you run them in series, if you don't know what that means, please don't hook up 2 4 ohm cabs.

Based on your questions, you'll want to read your manual carefully on a tube amp, they aren't as forgiving as SS amps about being hooked up incorrectly.

Roger

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honky_tonk

· #6 · Dec 21, 2005

also never have your amps standby turned on unless you have a speaker or speaker's hooked to it

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wallie!

Discussion Starter · #7 · Dec 22, 2005

Ant1981 said:
Cool, I'm thinking of getting a Marshall TSL100 so that I can channel switch clean and overdrive keeping that vavle tone, the tone is lost with a distortion/overdrive pedal. But I'm interested to know what the JSX sounds like.

Ive played on it a few weeks ago (the actual one joe used on tour)and it sounds great

The clean channel is very clean

So if the need arises to use pedals, they will go well

The crunch channel seamed pretty good, the gain around 5 got me a really nice sound.

The ultra channel (my favorite) sounded great on gain 5 as well, pushing that gets that really great sustained distorsion

The noise gate is orsm, especially on the ultra channel, especially with single coils, eliminating the hum , although ive read there is a slight loss in tone

The presence and resonace controls are great as well, if ur favourite settings dont sound right (say in a hall,a few adjustments of these controls and u will be right). Aside from the fact it doesnt have reverb, it was a great amp to play on, and it did blow me away. Ill post more up after xmas

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