4 ohm head to power 600 watt 8 ohm cab.

SPAZ5446 · #1 01-31-2011, 03:19 PM

I'm buying a 8 ohm 600 watt Carvin 4x10 cabinet from a seller on craigslist and was curious as to how much power would a 4 ohm head need to at least get 400 watts into the cabinet? I don't know the math behind this, most of the amps I've looked at show 4 ohm to 8 ohm to be a 60-70 watt reduction in power. However I've seen some heads that lose half their output going into a 8ohm load.

SPAZ5446 · #2 01-31-2011, 04:06 PM

Bump.

Marko5657 · #3 01-31-2011, 04:16 PM

I think an amp rated at around 600/650 watts at 4-ohms would get you right around 400 watts at 8 ohms.

I’ve never seen an amp where the 8-ohm rating is half the 4-ohm rating.

Btw, I think you’re wise to keep it around 400 watts instead of pushing the advertised limit.

BigOldHarry · #4 01-31-2011, 04:18 PM

"4 ohm head"...

What head would that be?

Heads aren't really rated by impedance, but they will have a "minimum load" rating. FWIW, my Ashdown has a min load of 4 ohms and I often run it with a single 8 ohm cab that is rated for 200 watts more than the amp can provide - sounds fine.

fivestringgecko · #5 01-31-2011, 04:23 PM

+1 to Harry

My main amp is a Shuttle 6.0 (600/375 watts @ 4/8 ohms) and it works great with either (or both) of my 8ohm cabs. Plenty loud!

5sg.

Marko5657 · #6 01-31-2011, 04:39 PM

Quote:

Originally Posted by BigOldHarry

"4 ohm head"...

What head would that be?
Heads aren't really rated by impedance, but they will have a "minimum load" rating. FWIW, my Ashdown has a min load of 4 ohms…

Would that not make your Ashdown a 4-ohm (capable) head?

The OP was simply asking how much power at a 4-ohm rating he should shoot for to get 400 watts at 8-ohms.

Why debate the semantics?

billfitzmaurice · #7 01-31-2011, 05:26 PM

Quote:

Originally Posted by SPAZ5446

I'm buying a 8 ohm 600 watt Carvin 4x10 cabinet from a seller on craigslist and was curious as to how much power would a 4 ohm head need to at least get 400 watts into the cabinet?

Chances are it will fart out at 300 watts anyway. Your owners manual should tell you how much power your amp will deliver into 8 ohms.

BigOldHarry · #8 01-31-2011, 05:34 PM

Quote:

Originally Posted by Marko5657

Would that not make your Ashdown a 4-ohm (capable) head?

The OP was simply asking how much power at a 4-ohm rating he should shoot for to get 400 watts at 8-ohms.

Why debate the semantics?

Debate? No - I was hoping to educate a bit. I know that when I started out, I'd see "4 ohm" on the back of a cab and figure I could only use a "4 ohm" cab - whatever that was. I had to learn.

The whole idea of impedance & loading is a bit illusive until you have someone really explain it to you in detail.

SPAZ5446 · #9 01-31-2011, 08:56 PM

If I get a head that pushes 600 watts at 4 ohms (which should be 375-400 watts at 8 ohms) and buy another 8 ohms cab later on, wire the two so the impedance is 4 ohms, will that 600 watt head split the power in half or still apply 600 watts to each cab?

Bass_Pounder · #10 01-31-2011, 08:57 PM

Power is shared

Sav'nBass · #11 01-31-2011, 09:10 PM

Quote:

Originally Posted by BigOldHarry

"4 ohm head"...

What head would that be?

Heads aren't really rated by impedance, but they will have a "minimum load" rating. FWIW, my Ashdown has a min load of 4 ohms and I often run it with a single 8 ohm cab that is rated for 200 watts more than the amp can provide - sounds fine.

For some reason that just cracked me up...

I always thought that most amps nowadays can run a 4 or 8 ohm load anyway.. so what you want to do is look at an amp like maybe a Shuttle 9.0 ... Just because the cab is rated at 600W doesnt mean you have to get anamp that is exactly 600W @ 8 ohms.. a 9.0 will do 500W@8 ohms/900W @ 4ohms.... I'd consider looking in the classifieds here at TB..

fivestringgecko · #12 01-31-2011, 09:29 PM

Quote:

Originally Posted by Bass_Pounder

Power is shared

This.

300 watts to each cab.

5sg.

Vintage Guy · #13 01-31-2011, 09:38 PM

Since I own several of these cabinets,I can give you my take on them. I have had no problem running mine with one of the old Carvin Redline 600 heads. Since they are a stereo head you can run a full 300 watts or run it bridged for more. Either way that cabinet will have enough thump to give you a nice rig.

SPAZ5446 · #14 02-01-2011, 11:15 AM

Is there a possibility I could spend only $200 dollars and still get a 500-600 watt head? I'm on a pretty tight budget.

fivestringgecko · #15 02-01-2011, 11:35 AM

If that's the case, you'll probably have to go with something used and watch for a deal.

5sg.

gregoire1 · #16 02-01-2011, 12:35 PM

Quote:

Originally Posted by SPAZ5446

Is there a possibility I could spend only $200 dollars and still get a 500-600 watt head? I'm on a pretty tight budget.

Peavey and Hartke

Emm9T · #17 02-01-2011, 12:44 PM

90's GK heads?