100v speakers at 8 ohms

[IA76]

Hi

 

When using a 100v amp why is it that if you run a 30w speaker at 100v it is much quieter than running it in 8 ohms mode.

 

What damage can be caused to the amp/speaker by running the speaker at 8 ohms on a 100v amp?

[paulears]

Damage depends on the design of the amp. However, the amplifier is expecting to drive into a high impedance load, and by comparison, you're applying essentially a short. The amp may be able to cope with this, maybe not. The entire point of a 100V system is that you can simply add in extra speakers, and as long as the total load doesn't exceed the amp's capability,volume at each speaker remains the same. With just one amp - one speaker, then you may get away with it. Long ago I had a TOA 100V line amp, 50W. Connecting an 8 Ohm speaker shut it down instantly. Many high impedance systems have good output protection because they may be driving different temporary systems each outing, so cable faults are pretty common - hence why they are well protected.

 

Do you really have no alternative to misloading the amp like this - many do have 8 ohm outputs too?

[BigKev]

Hi,

 

It will be louder for certain as you will be driving the amp into a much smaller load than it is supposed to be. The result will be a much higher current draw from the amplifier.

 

It will just be a case of waiting for either the speaker internals to melt or the transformer / protection circuitry on the amp to break. One of them will though.

 

Whats the rated output watts of the amplifier?

 

 

[IA76]

It's 360w 100v amp.

 

I don't intend on using the speakers in 8ohm mode. I just wanted to know why there was such a volume difference which had now been explained.

 

Thanks

[mario_s]

See other thing what cause volume difference in the example:

Speaker specification:

- resistance: 8Ohm

- power handling:100W cont. / 400W peak (8Ohm)

- transformer: 30W

In this case, SPL diference is almost 6dB(100W vs 30W) or even 12dB in peak(400W vs 30W) when You connect loudspeaker to 100V tap and to 8Ohm conector. Transformer of 100W would be too big, heavy and expensive and that is why many manufacturers use smaller transformers.