Trying to make sense of this Ohms stuff ...

[AMp'D.2play]

From what I've been reading, is this an accurate 'Clif Notes' version of acceptable combinations? (2 cabs max):

• 4 / 8 Ohm head + (1) 8 Ohm cab = ok
• 4 / 8 Ohm head + (2) 8 Ohm cabs = ok (4 Ohms each; more power than above)
• 4 / 8 Ohm head + (1) 4 Ohm cab = ok
• 2 / 4 or 2 / 4 / 8 Ohm head + (2) 4 Ohm cabs = ok (2 Ohms each)
• 4 / 8 Ohm head + (2) 4 Ohm cabs = no-no (2 Ohms each)

One of the combinations I'm looking at includes a 4 Ohm cab (Berg HT322 800w @ 4 Ohms). Unless I get a head that can run @ 2 Ohms, I wouldn't be able to add another cab down the road, correct? (not that I'd need to)

[smogg]

Correct,
Either 2ohm capable or 2X4ohm head like a Little Giant 1000 (2X500w @ 4ohms) or Shuttle Max 12 (2X600w @ 4ohms) or a Carvin BX1500 (2X450w @ 4ohms) just to name a few.

Also could go with a traditional rack set up pre + power amp.

[DWBass]

Originally Posted by AMp'D.2play

• 4 Ohm minimum head + (1) 8 Ohm cab = ok
• 4 Ohm minimum head + (2) 8 Ohm cabs = ok (4 Ohms total)
• 4 Ohm minimum head + (1) 4 Ohm cab = ok
• 2 Ohm minimum head + (2) 4 Ohm cabs or (4) 8 Ohm cabs = ok (2 Ohms total)
• 4 Ohm minimum head + (2) 4 Ohm cabs = no-no

Do not go below the minimum rated Ohms!

Fixed and easier to dicipher.

[Lazarus.Bird]

Seems it's a growing trend that more modern amps are able to go down to 2 ohms. Most tube amps also can go down to 2 ohms or have a selector switch. However, in general a lot of amps won't go below 4 ohms.

As smogg mentioned, some amps and power amps have two separate power amp channels, which is very beneficial if you plan on running two 4 ohm cabs but sometimes want just one. You'll still be able to send full power to one cab if you are doing a smaller gig and only want the one cab.

[AMp'D.2play]

Originally Posted by DWBass

Fixed and easier to dicipher.

Much obliged!

[bassplayerbob]

Originally Posted by smogg

Correct,
Either 2ohm capable or 2X4ohm head like a Little Giant 1000 (2X500w @ 4ohms) or Shuttle Max 12 (2X600w @ 4ohms) or a Carvin BX1500 (2X450w @ 4ohms) just to name a few.

Also could go with a traditional rack set up pre + power amp.

Add the Hartke LH1000 to this list. 450 bucks and you can run 4 cabs @4 ohms each in stereo mode. At 1st i wasnt sure on this,but an e mail to Larry Hartke's tech dept confirmed it.

[seamonkey]

Even when you get the ohms right, the speaker combination is what matters.
Mixing different size speakers is the luck of the draw

[DWBass]

Originally Posted by bassplayerbob

Add the Hartke LH1000 to this list. 450 bucks and you can run 4 cabs @4 ohms each in stereo mode. At 1st i wasnt sure on this,but an e mail to Larry Hartke's tech dept confirmed it.

4 4Ohm cabs or 4 8Ohm cabs? I thought that amp is still 4Ohm minimum per side??

Edit: Looks like that amp does go down to 2Ohms. Quoted from the manual below.

LH1000
Dual Parallel mode
2 x 225 watts @ 8 ohms
2 x 320 watts @ 4 ohms
2 x 545 watts @ 2 ohms
Bridge mode
1 x 750 watts @ 8 ohms
1 x 1100 watts @ 4 ohm

[bassplayerbob]

Originally Posted by DWBass

4 4Ohm cabs or 4 8Ohm cabs? I thought that amp is still 4Ohm minimum per side??

Edit: Looks like that amp does go down to 2Ohms. Quoted from the manual below.

Here is the e mail i sent to Hartke tech Dept to ease my mind:

From: Bob H [mailto:ribob@cox.net]
Sent: Sunday, February 28, 2010 11:25 AM
To: hartke@samsontech.com
Subject: LH1000 setup
Hi,
I am thinking of purchasing this head. My question is can I run (2) 4 ohm cabs on this head in parallel mode? I have owned Hartke heads in the past and the output jacks always say 8 ohms on each jack. These say 4 ohms on each jack, so in parallel mode does this mean I could use a 4 ohm cab in EACH speaker output? Since this is my only option because I really can’t afford to purchase 2 new 8 ohm cabs. Right now the 2 cabs are running on a qsc plx5 power amp at 700 per side with no problem.
Thanks
Bob
Answer

Bob,

Yes, you can run a 4ohm load out of each output in parallel mode.

Thank You,

Anthony DiMaggio
SamsonTech Product Specialist
800.372.6766
adimaggio@samsontech.com
www.samsontech.com

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So after that i headed down to grab the head and they were on backorder!! So i got the LH500 instead and use my single 15 with it.