Micro Terror 8 or 4 Ohm? What wattage?

Orange Amps Technical Q&A's

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guitarmikey
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Micro Terror 8 or 4 Ohm? What wattage?

Post by guitarmikey » Fri Sep 29, 2017 11:46 am

Hi there!
Proud owner of a Micro Terror, using it with different speakers (Ragin' Cajun, another Eminence, etc...)

I see now newer MT have written 8 Ohm on the back, mine has 4 Ohm. Any changes inside? If not, is there SAFE to connect to 4 Ohm speaker? Would it be a problem (so I've heard, seems to...)

If I connect to 8 Ohm speaker what will be the maximum output power, still 20W?
As I understood 20W are only in 4 Ohm, correct me if I'm wrong, please...

guitarmikey
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Re: Micro Terror 8 or 4 Ohm? What wattage?

Post by guitarmikey » Sat Oct 14, 2017 5:42 pm

Yeah... I see the answer is... no answer... Really Appreciated...

bclaire
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Re: Micro Terror 8 or 4 Ohm? What wattage?

Post by bclaire » Sat Oct 14, 2017 10:16 pm

Sorry - I have no idea. I think you'll be fine with either connection and I don't know that you could hear a difference in volume.

Rlw59
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Re: Micro Terror 8 or 4 Ohm? What wattage?

Post by Rlw59 » Sun Oct 15, 2017 4:32 pm

If you go to Orange's website and look up the Micro Terror you can download the manual for the current version labeled "8 ohm minimum". It says "A 4 Ohm load can be connected but may cause the amplifier to overheat if used for prolonged periods at high volumes. In this case the amp should be switched off and allowed to cool."

The original "4 ohm minimum" MT's sometimes triggered the thermal shutoff when cranked all the way up for long periods. Your playing style, ambient temperature, and the actual impedance curve of the speaker you're using all contribute to that, so some people had trouble and others didn't.

The thermal shutoff cycles on and off automatically. So as the amp's limit is approached it'll shut off, cool down a little, come back on, heat back up, shut off again, over and over. The hotter it gets the longer it stays shut off.

No reports of any damage, just annoying.

The thermal protection may be in the power supply rather than the amp. The power supply can only put out 30 watts, and several watts are used just to heat the tube so the power supply just barely puts out enough juice when the amp is putting out 20 watts. Some people say their shutoff problem went away when they used 15 volt power supplies rated at 2.5 amps or higher.

Orange worries about legal liability so they won't suggest/approve using a different power supply.

That's also why they don't release schematics or give in-depth technical details. So it's unclear if they changed anything internally when they changed the impedance labeling.

Since the manual says you can still use a 4 ohm load, that suggests they just changed the labeling on the speaker output jack. But if that's true, the 20W rating is a bit misleading. If it's still electronically the same you can only get 20W with 4 ohms. With an 8 ohm load it's roughly a 10 watt amp, with a 16 ohm load it's approximately 5 watts.

The difference between 20 watts and 10 watts is about 3dB. Not really a huge difference. Playing by yourself it's barely noticeable, but in a band it can be the difference between being heard and being buried.

In my apartment, with the gain halfway up I can barely crack open the master running into an 8 ohm load. And it sounds kind of strangled with the master that low. Into 16 ohms I can turn the master up a notch and it sounds better. Even better with two 16 ohm speakers in series for a 32 ohm load. Still can't turn the master much higher than 10 o'clock unless I have the gain very low for clean sounds.

But I have efficient speakers and live in a small apartment. One watt gives around 100dB at 3 meters. So 32 ohms vs 8 ohms is noticeable. In a bigger room in a house it would be less significant.

bclaire
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Re: Micro Terror 8 or 4 Ohm? What wattage?

Post by bclaire » Sun Oct 15, 2017 5:18 pm

Thanks - I should have mentioned the manual.

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