Can I use an 8 ohm amp into a 4 ohm cab?

Zaney · #1 04-15-2010, 02:59 PM

I've been offered a Hartke 200w amp head cheap but on the back it states 8ohms. My cab is 4 ohms. Is this compatible?
Thanks for a reply

Bass_Pounder · #2 04-15-2010, 03:00 PM

If 8 ohms is the minimum, then NO you cannot run a 4 ohm cab

JimiLL · #3 04-15-2010, 03:01 PM

nooooo. id stear cclear of that head anyways.... not enough power to really efficently run anything.

Save up some cash and shoot for at least another 100 watts. And one that runs 4 ohms

Edword · #4 04-15-2010, 03:24 PM

My Traynor YBA-3 manual says I could use one or two 4-ohm cabinets with the 8-ohm amp, but it's a very old valve amp that probably doesn't have much in common with yours.

badboy1984 · #5 04-15-2010, 03:32 PM

200watt head that can drive one single 8ohm cab is not alot of power.

I say look for another head that is listed as 4ohm.

Turock · #6 04-15-2010, 04:24 PM

I would be willing to bet that head is designed to run at 4 ohms. If it is the 2000 series head, running 4 ohms is the only way to get 200 watts. Does it have two 8 ohm jacks?

RickenBoogie · #7 04-15-2010, 04:48 PM

+1, I'd be surprised if that amp isn't rated for 4 ohms.

Zaney · #8 04-15-2010, 05:08 PM

yes it has two speaker jacks. how would I connext to a single input on my cab though?

RickenBoogie · #9 04-15-2010, 05:10 PM

With a speaker cable. One output from amp, to one input on speaker cab.

Turock · #10 04-15-2010, 05:12 PM

Quote:

Originally Posted by Zaney

yes it has two speaker jacks. how would I connext to a single input on my cab though?

Just run a speaker cable from one of the jacks to your cab. Don't try to run another cabinet (4 or 8 ohms) at the same time.

Zaney · #11 04-15-2010, 05:14 PM

what is the purpose of the amp have two speaker jack outputs?

billfitzmaurice · #12 04-15-2010, 05:17 PM

Quote:

Originally Posted by Zaney

what is the purpose of the amp have two speaker jack outputs?

To run two 8 ohm cabs.

Zaney · #13 04-15-2010, 05:22 PM

so am I right in assuming it will be ok to run this 8 ohm amp from one speaker jack to my 4 ohm cab?

Turock · #14 04-15-2010, 05:28 PM

Quote:

Originally Posted by Zaney

so am I right in assuming it will be ok to run this 8 ohm amp from one speaker jack to my 4 ohm cab?

Most likely, it's not an 8 ohm amp (what is the model?). it has two jacks marked 8 ohms so that you won't try to use two 4 ohm cabinets. It should be fine at 4 ohms.

Zaney · #15 04-15-2010, 05:32 PM

Its a 200w hartke transient model 2000 head removed from a combo.
I'll find a pic and post

badboy1984 · #16 04-15-2010, 05:36 PM

i guess is all clear now that his Hartke amp is 200watt rated 4ohm.

So basically that means you can run two 8ohm cab so it becomes 4ohm to get the full 200watt power or you can run one 4ohm cab to get the full power as well.

Or you can run one 8ohm cab but you will only get around 100-120watt power.

DON'T try to run two 4ohm cab or your amp (might be cab) will get some serious damage.

Zaney · #17 04-15-2010, 05:37 PM

here it is

Name: hartke amp back view.jpg
Views: 292
Size: 1.5 KB

keyboardguy · #18 04-15-2010, 11:14 PM

Here's the Hartke 2000 specs:
==================
200 watts at 4 ohms/120 watts at 8 ohms.
Selectable tube & solid state preamps. Bass & treble Contour controls. 10-band graphic EQ. Adjustable compression. Effects loop.

Power: 200 Watts at 4 Ohms
120 Watts at 8 Ohms
Selectable Tube & Solid-State Preamps
Rotary Bass & Treble Contour Controls
10-Band Graphic Eq
Adjustable Compression
Total Harmonic Distortion: Less Than 1% At Rated Power
Signal-To-Noise: Approx. 70 dBm
Effects Send & Return
Bipolar Design
Passive/Active Input Jack
Rack-Mountable
Dimensions: 2U Space, 13" Deep

Munjibunga · #19 04-15-2010, 11:42 PM

Quote:

Originally Posted by Zaney

I've been offered a Hartke 200w amp head cheap but on the back it states 8ohms. My cab is 4 ohms. Is this compatible?
Thanks for a reply

What model is it? The Hartke 2000 can handle a 4-ohm load. In fact, it develops its 200 watts of power at 4 ohms, and only 120 watts at 8 ohms. It has two jacks marked 8 ohms, and you can plug an 8-ohm cab in each one. Since the jacks are parallel, you could plug a 4-ohm cabinet into one (but not both) of the jacks.

Here's a link to the manual.

Alex1984 · #20 04-16-2010, 04:11 PM

Yep. Like many have said, single 8 ohm @ 120W, double 8 ohm @ 200W, or single 4 ohm @ 200W.

Anything below that, even a 8 and a 4, you risk overdrawing current, causing overheating and ultimately amp failure. But realistically, that's kinda silly, 'cuz mismatching impedance means unevenly distributed power, though it can sometimes be used to compensate for mismatched sensitivity, but it's just too much of a hassle to think about.