Coliseum Bass Head: What Cabs Should I Run?

BRAILLE · 06-20-2007, 03:51 AM

This is my first ever bass head and I'm very excited about it. The head is rated at 200 watts and 2 OHMs. I've read a few articles on OHMs and wattage but I can't seem to fully understand the concept... I will read a few more articles later but for right now I'm sick of sitting infront of the comptuer. Anyway, I was curious what you'd reccomend I run out of this amp? Would it be possible to run a 1x15 and 4x10? If any of you could reccomend me combos of what I could run out of the amp I'd appreciate it! I would also appreciate it if anyone could post useful websites that have info on OHMs and wattage!

Thanks

David Schwab · 06-20-2007, 11:16 PM

OK, it's like this. Here's a simplified example... If you have two 8-ohm speakers, and plug one in each speaker jack, that's 4 ohms. If you have two 4-ohm speakers, that gives you 2 ohms. If you have 4 8-ohm speakers, that's 2 ohms (wired in parallel).

With solid state heads, you can run them at higher impedances, but not lower than rated. So if you ran that head at 4 ohms, you'd get less than the 200 watts, but it would work fine.

So for a 15" and 4x10's, each cabinet will have to be 4 ohms to get the full power. So figure on a 4 ohm 15", and each 10" speaker would have to be either 16 ohms, so all four in parallel would be 4 ohms, or 4 ohms each, with two pairs in series (8 ohms) and then the two pairs in parallel to give you 4 ohms.

2 ohm heads are pretty rare these days. And if you are buying speaker cabs already loaded, it might be hard to get them at 4 ohms.

Two 8 ohm cabs would work, but you'd get a bit less output.

Those are nice heads. I used to use one back in the 70's. You can hear them on the Who's Quadrophenia album.

BRAILLE · 06-23-2007, 04:53 AM

Awesome, I understand now! I posted the same thread on the sunn forums and they recommended that I use a 4 OHM load rather than a 2 OHM load because "it's better to be safe than... on fire" Do you think I should take their advice in running a 4 OHM load rather than 2? I am very tempted to run 2 OHMs!

Thanks for your help!

P.S.

Your icon freaks me out!

loudthud · 06-23-2007, 05:32 PM

On the Sunn forum you called the amp a Concert and on here you called it a Coliseum. They are two different amps, which do you have?

Early versions of the Concert series were 150W @ 4 ohms. There may be later versions rated at 200W but I have never seen one. Early versions of the Coliseum series were 300W @ 2 ohms and later they were rated at 320W @ 2 ohms. At 4 ohms, a Coliseum puts out about 200W.

A Coliseum will safely run 2 ohms as long as the fan still works and air is not blocked. It's a good idea to open the thing up and blow out any dust that has accumulated inside. Replace the rubber feet on the bottom of the amp if they are broken or missing because the air intake is on the bottom of the amp.

An early Concert will probably die at 2 ohms because there is no current limiting on the output transistors.

If you are playing outside on a hot day, it's a good idea to get a box fan to blow on the back of either amp.

David Schwab · 06-23-2007, 07:54 PM

Quote:

Originally Posted by BRAILLE

Your icon freaks me out!

Why's that?

I do need to smile more...

BRAILLE · 07-02-2007, 08:23 PM

Loadthud - Oops... The amp is a newer Concert bass, it's all black with a red logo and knobs. Do you think I could run 2 OHMs with this version?

Dave - No hard feelings! The look you're giving is just kind funny... I don't know there's just something weird about the picture.

BRAILLE · 07-09-2007, 08:08 AM

I have a question regarding this OHM buisness:

Recently picked up a concert bass head that's rated at 200 watts and 2 OHMs.

I plan on building two 8 OHM cabs to run my amp at 4 SAFE OHMs.

The cabs I want to build are 1 4x12 and 1 2x15 (or instead of the 2x15 one 1x18)

Anyone know if the concert bass could handle this combo? Would each individual cab need to be close to 200 watts? Or 100 watts to equal to 200 watts? Or could the cabs be built with around 500 watts? Please fill me in on this!

black_labb · 11-08-2007, 02:56 AM

Quote:

Originally Posted by BRAILLE

I have a question regarding this OHM buisness:

Recently picked up a concert bass head that's rated at 200 watts and 2 OHMs.

I plan on building two 8 OHM cabs to run my amp at 4 SAFE OHMs.

The cabs I want to build are 1 4x12 and 1 2x15 (or instead of the 2x15 one 1x18)

Anyone know if the concert bass could handle this combo? Would each individual cab need to be close to 200 watts? Or 100 watts to equal to 200 watts? Or could the cabs be built with around 500 watts? Please fill me in on this!

you want them together to equal something equal or higher than 200 watts. for example, the 15" speaker will be taking 50 watts each (think of the unit splitting to the 2 cabs, then splitting again to get to the individual speakers) and the 12" taking 25 watts each. aslong as the values are equal or larger than these values then you will be fine. you would be hard pressed to find a 15" bass speaker rated at under 100 watts, nevermind 50, and 12's would be the same, so you can virtually use any speakers aslong as they are the correct impedance.

06-20-2007, 03:51 AM	#1
BRAILLE Junior Member Join Date: Jun 2007 Posts: 5	Coliseum Bass Head: What Cabs Should I Run? This is my first ever bass head and I'm very excited about it. The head is rated at 200 watts and 2 OHMs. I've read a few articles on OHMs and wattage but I can't seem to fully understand the concept... I will read a few more articles later but for right now I'm sick of sitting infront of the comptuer. Anyway, I was curious what you'd reccomend I run out of this amp? Would it be possible to run a 1x15 and 4x10? If any of you could reccomend me combos of what I could run out of the amp I'd appreciate it! I would also appreciate it if anyone could post useful websites that have info on OHMs and wattage! Thanks

06-20-2007, 11:16 PM	#2
David Schwab Pickup Maker Join Date: May 2006 Location: Montclair, NJ Posts: 5,624	OK, it's like this. Here's a simplified example... If you have two 8-ohm speakers, and plug one in each speaker jack, that's 4 ohms. If you have two 4-ohm speakers, that gives you 2 ohms. If you have 4 8-ohm speakers, that's 2 ohms (wired in parallel). With solid state heads, you can run them at higher impedances, but not lower than rated. So if you ran that head at 4 ohms, you'd get less than the 200 watts, but it would work fine. So for a 15" and 4x10's, each cabinet will have to be 4 ohms to get the full power. So figure on a 4 ohm 15", and each 10" speaker would have to be either 16 ohms, so all four in parallel would be 4 ohms, or 4 ohms each, with two pairs in series (8 ohms) and then the two pairs in parallel to give you 4 ohms. 2 ohm heads are pretty rare these days. And if you are buying speaker cabs already loaded, it might be hard to get them at 4 ohms. Two 8 ohm cabs would work, but you'd get a bit less output. Those are nice heads. I used to use one back in the 70's. You can hear them on the Who's Quadrophenia album. __________________ Those who create are rare; those who cannot are numerous. Therefore, the latter are stronger. - Coco Chanel www.sgd-lutherie.com www.myspace.com/sgdlutherie www.myspace.com/davidschwab

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06-23-2007, 04:53 AM	#3
BRAILLE Junior Member Join Date: Jun 2007 Posts: 5	Awesome, I understand now! I posted the same thread on the sunn forums and they recommended that I use a 4 OHM load rather than a 2 OHM load because "it's better to be safe than... on fire" Do you think I should take their advice in running a 4 OHM load rather than 2? I am very tempted to run 2 OHMs! Thanks for your help! P.S. Your icon freaks me out!

06-23-2007, 05:32 PM	#4
loudthud Supporting Member Join Date: May 2006 Location: Texas USA Posts: 923	On the Sunn forum you called the amp a Concert and on here you called it a Coliseum. They are two different amps, which do you have? Early versions of the Concert series were 150W @ 4 ohms. There may be later versions rated at 200W but I have never seen one. Early versions of the Coliseum series were 300W @ 2 ohms and later they were rated at 320W @ 2 ohms. At 4 ohms, a Coliseum puts out about 200W. A Coliseum will safely run 2 ohms as long as the fan still works and air is not blocked. It's a good idea to open the thing up and blow out any dust that has accumulated inside. Replace the rubber feet on the bottom of the amp if they are broken or missing because the air intake is on the bottom of the amp. An early Concert will probably die at 2 ohms because there is no current limiting on the output transistors. If you are playing outside on a hot day, it's a good idea to get a box fan to blow on the back of either amp.

07-02-2007, 08:23 PM	#6
BRAILLE Junior Member Join Date: Jun 2007 Posts: 5	Loadthud - Oops... The amp is a newer Concert bass, it's all black with a red logo and knobs. Do you think I could run 2 OHMs with this version? Dave - No hard feelings! The look you're giving is just kind funny... I don't know there's just something weird about the picture.

07-09-2007, 08:08 AM	#7
BRAILLE Junior Member Join Date: Jun 2007 Posts: 5	I have a question regarding this OHM buisness: Recently picked up a concert bass head that's rated at 200 watts and 2 OHMs. I plan on building two 8 OHM cabs to run my amp at 4 SAFE OHMs. The cabs I want to build are 1 4x12 and 1 2x15 (or instead of the 2x15 one 1x18) Anyone know if the concert bass could handle this combo? Would each individual cab need to be close to 200 watts? Or 100 watts to equal to 200 watts? Or could the cabs be built with around 500 watts? Please fill me in on this!

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