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Another Ohm question

#2
The Artist said:
Hi
I have a Trace Elliot GP7SM 200 which gives out 200w at 8ohm
My cab is a 4x10 400w 4ohm

I have played like that for years and only just noticed:hiding:

What difference does it make?
May I be doing damage to either part?

Thanks ;)
Alexx
Click to expand...

Most amps can be run at a 4ohm load, but that generally means you are producing more wattage and consequently pulling more amperage. Most amps will NOT like running at 2ohms though, and will damage an amp that is not rated for it.

If you're pushing 200W at 8ohms, that means you're pushing more than that with the 4ohms.
 
#5
The Artist said:
There are only two "8 Ohm" outs on the back and nothing to change this.

Thanks ;)

...so the amp will be suffering and not the cab?


cheers
Alexx
Click to expand...

From what I've been able to find, that amp will work down to 4 ohms. You've been running it into a 4 ohm speaker so you're okay. Just don't add another speaker with that setup or you'll drop below the minimum 4 ohms.
 
#8
maxbass said:
You amp puts out 200 watts at 4 ohm.
At 8 ohm, you are getting about 130/140 watts I think.

There's nothing armful, of course your cab would sound louder and better with a more powerful amp.
Click to expand...

does it?
Seeing as there are two 8ohm plugs at the back, does that mean if i only use one of then that I am running 4 ohms?

hypatheticly: what would happen if I plug in both 8ohm outs to my cab (which has two sockets on the back)
cheers Alexx
 
#10
The Artist said:
does it?
Seeing as there are two 8ohm plugs at the back, does that mean if i only use one of then that I am running 4 ohms?

No. The impedance of your cabinet determines that.

hypatheticly: what would happen if I plug in both 8ohm outs to my cab (which has two sockets on the back)
cheers Alexx
Click to expand...

It should work just as well. There's no real advantage to doing it though, assuming your speaker cable is of sufficient guage already and you're using a regular speaker cable (not an instrument cable) and it's not ridiculously long you're fine..
 
#11
62bass said:
It should work just as well. There's no real advantage to doing it though, assuming your speaker cable is of sufficient guage already and you're using a regular speaker cable (not an instrument cable) and it's not ridiculously long you're fine..
Click to expand...

I hate to sound horrably noobish, but what is the difference between speaker and instrument cable? (exept length)
:hiding:

I have never realy concerned myself with these things, but wish to and should learn more as to evolve ;)
 
#12
The Artist said:
I hate to sound horrably noobish, but what is the difference between speaker and instrument cable? (exept length)
:hiding:

I have never realy concerned myself with these things, but wish to and should learn more as to evolve ;)
Click to expand...

This is something that came up in a thread a few weeks ago.

Basically, instrument cables are meant to be used between your bass and the amp. The speaker cables are meant to run from the amp to the cab.

The power running from your bass to the amp is very minimal and therefore needs only so much wire thickness in the cable. But, it is not suitable for amp-to-cab applications because the power running between those two means a thicker guage wire is needed. Thin wire with high wattage could mean a glowing red wire. :hmm: At low volumes (like practicing in your bedroom) it would not be an issue. If you're at a gig and cranking, it would soon be an issue using the instrument cables between amp and cab.
 
#17
The Artist said:
does it?
Seeing as there are two 8ohm plugs at the back, does that mean if i only use one of then that I am running 4 ohms?

hypatheticly: what would happen if I plug in both 8ohm outs to my cab (which has two sockets on the back)
cheers Alexx
Click to expand...

You would definitely harm the head and probably the cab. DO NOT do this!!!
I can't go into depth, trust me there are people who will explain this and already have in other threads.
 
#18
It sounds like your head has two 8-ohm outputs. If you connect two 8-ohm speaker cabinets to the two 8-ohm outputs, you end up with 4-ohms of equivalent impedance. It is most likely that the 8-ohm outputs are connected to the same point in the amp. Meaning if you connected them both to the same cabinet, you would just have less wiring loss (no big deal). But if the two 8-ohm outputs connect to different power amp stages, you would not want to connect them to the same load. That would be bad.
 
#19
AfroMan Skeeter said:
You would definitely harm the head and probably the cab. DO NOT do this!!!
I can't go into depth, trust me there are people who will explain this and already have in other threads.
Click to expand...

Not unless each of those 8 ohm speaker outputs came from a separate amp--in other words, if it was a stereo amplifier. His amp is a Trace Elliot GP7SM which is not a stereo amp. It's one amp. Mono. It's rated to operate safely to 4 ohms. He can connect an 8 ohm cabinet to each of those speaker cabinets safely and will thereby be operating at 4 ohms, and getting the full power available from his amp.
 

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