Speaker Ohms Question:

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Inspector #20

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My 8200 Valvestate is a 4 ohm minimum amp, like my MG100. The back panel reads '4 ohms 100 watts 8 ohms 80 watts.'

On both amps, I run the outputs to an individual speaker.

20211229_210843.jpg

Now, I have read that some speakers are never right on their advertised ohms rating, for example, a 4 ohm could be 3 or 5 ohms.

My speakers are available in 4, 8 and 16 ohm variations.

Thoughts???
 
Robert Herndon said:
My 8200 Valvestate is a 4 ohm minimum amp, like my MG100. The back panel reads '4 ohms 100 watts 8 ohms 80 watts.'

On both amps, I run the outputs to an individual speaker.

View attachment 78326

Now, I have read that some speakers are never right on their advertised ohms rating, for example, a 4 ohm could be 3 or 5 ohms.

My speakers are available in 4, 8 and 16 ohm variations.

Thoughts???
Click to expand...
The only thing I know is at the maximum 4 ohms is when you get full power from the amp, both of my 3210’s see a 4 ohm load for the full spectrum ..
Never actually measured one of the cabs.
Thanks
 
Mitch Pearrow SJMP said:
The only thing I know is at the maximum 4 ohms is when you get full power from the amp, both of my 3210’s see a 4 ohm load for the full spectrum ..
Never actually measured one of the cabs.
Thanks
Click to expand...

Correct. For example, I am currently running dual 16ohm speakers and that's fine. 4ohms would (as you have pointed out) allow the amp to provide maximum output. My only concern is if a speaker had slightly less than rated ohms...
 
Robert Herndon said:
Correct. For example, I am currently running dual 16ohm speakers and that's fine. 4ohms would (as you have pointed out) allow the amp to provide maximum output. My only concern is if a speaker had slightly less than rated ohms...
Click to expand...
On a solid state amp this is true.
4 ohms maximum wattage. But also the most heat from the transistors.
8 ohms = 1/2 power.
16 ohms 1/4 power.

But the funny thing is, wattage does not = loudness.
Speaker efficiency is what makes it loud.
There is speaker which gets 102 db SPL with 1 watt input.
And there is lots of speakers which get less than 1/2 as loud.

See?
If you want wattage to = loudness, then you need a speaker that can achieve the loudness to start with.
There is lots of inefficient speakers but only a few really good ones.
 
Last edited:
Amp Mad Scientist said:
On a solid state amp this is true.
4 ohms maximum wattage. But also the most heat from the transistors.
8 ohms = 1/2 power.
16 ohms 1/4 power.

But the funny thing is, wattage does not = loudness.
Speaker efficiency is what makes it loud.
There is speaker which gets 102 db SPL with 1 watt input.
And there is lots of speakers which get less than 1/2 as loud.
Click to expand...

Ok,

I'm glad I asked.

So on my amp, the Copperback Neodymiums are available in 8
4, 8 and 16 ohms. All are 100db spl.

Which would be best in your opinion???
 
Speakers are rated at nominal impedance. It will change w frequency etc. Measuring a 4 ohm spekaer will read somewhere around 3. something. That is fine. No worries, that is what a 4 ohm rated speaker will read.
If you want max output go with the 4 ohm for each side. Otherwise no difference. 8 is fine too at 80 watts per side. I mean, how much does one need? Very little difference in output between 100 and 80.
 
Last edited:
Robert Herndon said:
Ok,

I'm glad I asked.

So on my amp, the Copperback Neodymiums are available in 8
4, 8 and 16 ohms. All are 100db spl.

Which would be best in your opinion???
Click to expand...
16 ohms is always the best choice because it gives the option of adding the most speakers.
(at 16 ohms I can run 4 speakers in parallel...)
how many 8 ohm speakers can I run? only 2.
As far as ohms goes there's not going to be a major difference in loudness unless you add more speakers...

This is because one speaker can only get "so loud," and then cannot go any louder.
The speaker saturates.
This is because it takes 10X the power to make a speaker SPL twice as loud. (up until it's limit of loud) That's only 3 db difference.

I would rather run at 16 ohms or 8 ohms and save the heat in a solid state amp.
More speakers is more efficient loudness wise.
If I need more loudness I can add more speakers. Why not let the amp run cooler?

In a tube amp, there is a difference.
It is not the same as SS amp heat wise.
The tube amp matches 4/8/16 ohm and the power heat is not changed, provided the load is correct.
 
Amp Mad Scientist said:
16 ohms is always the best choice because it gives the option of adding the most speakers.
(at 16 ohms I can run 4 speakers in parallel...)
how many 8 ohm speakers can I run? only 2.
As far as ohms goes there's not going to be a major difference in loudness unless you add more speakers...

This is because one speaker can only get "so loud," and then cannot go any louder.
The speaker saturates.
This is because it takes 10X the power to make a speaker SPL twice as loud. (up until it's limit of loud) That's only 3 db difference.

I would rather run at 16 ohms or 8 ohms and save the heat in a solid state amp.
More speakers is more efficient loudness wise.
If I need more loudness I can add more speakers. Why not let the amp run cooler?

In a tube amp, there is a difference.
It is not the same as SS amp heat wise.
The tube amp matches 4/8/16 ohm and the power heat is not changed, provided the load is correct.
Click to expand...
Unless one wants to maximize output which is a 4 ohm load. Whether that is 2x8s or 4x16s is up to Robert. 8 ohms at 80 watts is lots IMO
 
Amp Mad Scientist said:
16 ohms is always the best choice because it gives the option of adding the most speakers.
(at 16 ohms I can run 4 speakers in parallel...)
how many 8 ohm speakers can I run? only 2.
As far as ohms goes there's not going to be a major difference in loudness unless you add more speakers...

This is because one speaker can only get "so loud," and then cannot go any louder.
The speaker saturates.
This is because it takes 10X the power to make a speaker SPL twice as loud. (up until it's limit of loud) That's only 3 db difference.

I would rather run at 16 ohms or 8 ohms and save the heat in a solid state amp.
More speakers is more efficient loudness wise.
If I need more loudness I can add more speakers. Why not let the amp run cooler?

In a tube amp, there is a difference.
It is not the same as SS amp heat wise.
The tube amp matches 4/8/16 ohm and the power heat is not changed, provided the load is correct.
Click to expand...

I'm running a 2x12 with each speaker being driven by its own cable from one output of the 8200.

8 ohms would probably be a good compromise in that I could demo amps like a DSL40 or an Origin (on one speaker) with my 2x12 cabinet.
 
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