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Watts and ohms


hitchy64
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Hi all,
I am currently using a Carlsbro 4x12 cab and an Ashdown EB180 115 combo on top, conected together.
This works well and I'v got a great sound, but I don't want to cart around the Ashdown combo as well when we start gigging. I want to DI straight into the mixer and am looking for a head to cut down on space/weight. I'm thinking of the Marshall MB450H head, my mates got one and says it's good.
I don't understand Watts and ohms and what means what!!
My Carlsbro vintage 4x12 says 120 watts, 16 ohms.
Is this good or bad, and will a 450watt head sound ace with this cab.
Thanks in advance,
Hitchy.

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Sounds like your Carlsbro is a guitar cab if it's only 120 watts. You'll be ok driving it with the Ashdown because you'll only be putting about 90 watts into it, but the Marshall is a different matter. You could well blow something.

How about getting a smaller extension speaker for the Ashdown?

Doh! If it's 16ohms you won't be getting 90 watts out of the Ashdown

Edited by AndyMartin
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[quote name='hitchy64' post='696530' date='Dec 30 2009, 05:54 PM']Hi all,
I am currently using a Carlsbro 4x12 cab and an Ashdown EB180 115 combo on top, conected together.
This works well and I'v got a great sound, but I don't want to cart around the Ashdown combo as well when we start gigging. I want to DI straight into the mixer and am looking for a head to cut down on space/weight. I'm thinking of the Marshall MB450H head, my mates got one and says it's good.
I don't understand Watts and ohms and what means what!!
My Carlsbro vintage 4x12 says 120 watts, 16 ohms.
Is this good or bad, and will a 450watt head sound ace with this cab.
Thanks in advance,
Hitchy.[/quote]

That amp is rated at 450W into 2 ohms, which is the equivalent of a rusty nail over the outputs. It's rated at 300W into 4 ohms and dunno what into 8 or 16. 16ohms is a really weird rating. It was probably designed to be used as two 16 ohm cabinets which together (in parallel) give 8. It would probably work and the amp would **probably** not blow it up but that's only because it would be massively down on power. It's going to be a bit tricky to do anything with a 16ohm cab frankly.

Dunno if any of this helps. I can go into (lots) more detail if you want.

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[quote name='AndyMartin' post='696536' date='Dec 30 2009, 05:59 PM']Sounds like your Carlsbro is a guitar cab if it's only 120 watts. You'll be ok driving it with the Ashdown because you'll only be putting about 90 watts into it, but the Marshall is a different matter. You could well blow something.

How about getting a smaller extension speaker for the Ashdown?

Doh! If it's 16ohms you won't be getting 90 watts out of the Ashdown[/quote]

Agree completely... that's a guitar cab. That's always going to be a problem. If you're spending money then better get a proper cab IMHO (or sell everything and start again)

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[quote name='hitchy64' post='696530' date='Dec 30 2009, 05:54 PM']Hi all,
I am currently using a Carlsbro 4x12 cab and an Ashdown EB180 115 combo on top, conected together.
This works well and I'v got a great sound, but I don't want to cart around the Ashdown combo as well when we start gigging. I want to DI straight into the mixer and am looking for a head to cut down on space/weight. I'm thinking of the Marshall MB450H head, my mates got one and says it's good.
I don't understand Watts and ohms and what means what!!
My Carlsbro vintage 4x12 says 120 watts, 16 ohms.
Is this good or bad, and will a 450watt head sound ace with this cab.
Thanks in advance,
Hitchy.[/quote]

4 speakers 16 ohms...interesting....wonder how its wired...or if it uses 4 ohm speakers

?

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Was just thinking, if it uses 4x 4 ohm speakers in series, you could easily rewire it to make a 4-ohm cab (or a 1-ohm, lol)

But, as correctly stated above, you'd blow it up unless you were very careful how you drove it.

A lot of guitar extension cabs are 16 ohm - my guitarist's Vox modelling amp requires a 16 ohm extension, and can't drive an 8-ohm. Maybe it's cause a lot of cabs are 8 ohm standard and they want people buying a same brand cab? Sneaky buggers.

I have the MB4210 combo which is the MB450 head you're considering bolted into a 2x10". It definitely kicks arse. If you want to downsizse your rig and like the MB range, maybe sell your existing combo and extension cab, and buy either a MB head and 4x10, or the 4x10 combo they do? (Be warned that thing is b45t4rd heavy though, seperates might be well advised)

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[quote name='mrcrow' post='696557' date='Dec 30 2009, 06:10 PM']4 speakers 16 ohms...interesting....wonder how its wired...or if it uses 4 ohm speakers

?[/quote]

The only thing I have seen like this actually had 16 ohm speakers. You had two 8 ohm (paralell) "stereo" channels or a single 16ohm (series, parallel), switchable. Wonder if this is the same?

EDIT:
Of course, 4 16ohm speakers in parallel gives you 4ohms, but the cab will only ever be 120W power handling which isn't a great deal of use for bass. The Marshall head would cook it.

Edited by thepurpleblob
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[quote name='Tinman' post='696541' date='Dec 30 2009, 06:01 PM']Stacks of info here - [url="http://wiki.basschat.co.uk/info:amps:impedance_and_wattage"]http://wiki.basschat.co.uk/info:amps:impedance_and_wattage[/url]

It's written by some very knowledgeable people and should tell you all you need to know :)[/quote]

Yes. Read that sticky. READ IT.

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most of the original 4x12s in the 60s which designed to pair up with a 50 or 100w valve head.were 16 ohm

there were ususlly 4 x 15 ohm speakers wired up as series / parrellel. 2 pairs each wired in series giving 30 ohms, and then those 2 pairs wired in series coming back to 15 ohm.

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Thanks for all the replys.
I'v only had the cab maybe 2 months, I'm gonna take it back to the shop first thing in the morming and demand my money back. The idiot should have known what he was selling me, I bought a Carlsbro head off him at the same time and took that back the same day because it was'nt working properly ( second hand). I tried the cab with one of his bass's in the shop, so he knew what I wanted. The Twat!!!!

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Oh dear. Have you googled the model number to double check what it is actually for. I would go armed with all the facts.

Don't let them bullshit their way out of giving you a refund. If they sold you it as a bass cab and it is definitely a guitar cab then it really isn't suitable for bass. Probably the only reason it hasn't fried is because you haven't been putting a lot of power into it

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[quote name='thepurpleblob' post='696547' date='Dec 30 2009, 06:05 PM']Agree completely... that's a guitar cab. That's always going to be a problem. If you're spending money then better get a proper cab IMHO (or sell everything and start again)[/quote]

+1 regardless of the power ratings and resistances a guitar cab is a guitar cab and a bass cab is a bass cab, you shouldn't run a bass at anything more than bedroom practice volume in a guitar amp or speaker.

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Check first!

Marshall made 120 watt 4x12 cabs which could be used for both bass and guitar - they were designated seperate model numbers on the rear panel. The cabs were known as models 1982A and 1982B, and contained 'heavy duty' Celestion G12 speakers.
Many variations of the G12 speaker were being made available, and Marshall did not always increase the power capacity of their cabinets at the same time as Celestion improved the spec of their speakers - for a while Marshall claimed a capacity of 120 watts for one of their 4x12's when in fact the cabinet could handle in the region of 320 watts.

I think all the 4x12's were only available in 16 ohm format - as previous post mentions,this was to marry up a pair of cabs to valve heads thus
giving an ideal load of 8 ohms. 16 ohm cabs not therefore great to use alone with a transistor head!

Hope this helps!
Pete.

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[quote name='casapete' post='696977' date='Dec 31 2009, 09:45 AM']Check first!

Marshall made 120 watt 4x12 cabs which could be used for both bass and guitar - they were designated seperate model numbers on the rear panel. The cabs were known as models 1982A and 1982B, and contained 'heavy duty' Celestion G12 speakers.
Many variations of the G12 speaker were being made available, and Marshall did not always increase the power capacity of their cabinets at the same time as Celestion improved the spec of their speakers - for a while Marshall claimed a capacity of 120 watts for one of their 4x12's when in fact the cabinet could handle in the region of 320 watts.

I think all the 4x12's were only available in 16 ohm format - as previous post mentions,this was to marry up a pair of cabs to valve heads thus
giving an ideal load of 8 ohms. 16 ohm cabs not therefore great to use alone with a transistor head!

Hope this helps!
Pete.[/quote]

+1 Hiwatt did cabs for both bass and guitar as well.

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[quote name='bumnote' post='696605' date='Dec 30 2009, 06:39 PM']most of the original 4x12s in the 60s which designed to pair up with a 50 or 100w valve head.were 16 ohm

there were ususlly 4 x 15 ohm speakers wired up as series / parrellel. 2 pairs each wired in series giving 30 ohms, and then those 2 pairs wired in series coming back to 15 ohm.[/quote]

magic!! :)

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