Another impedence question

[nopicknick]

If I put a 8 ohm and a 16 ohm speaker together in a 212 cab how would that sound......also depending on how I wire it would it be what a 10 ohm cab?

 

[domct203]

Wired parallel the total load is 5.33 ohms ( (8X16)/(8+16) ). Wired in series it would be 24 ohms (8+16).

Are you talking about two of the same model speakers or two completely different speakers?

Dom

 

[nopicknick]

Speakers are a 8 ohm WGS ET65 at 65 watts and a 16 ohm WGS Green Beret at 25 watts. Will the 8 ohm ET65 be louder than the 16 ohm Green Beret wired parallel?

 

[domct203]

Speakers are a 8 ohm WGS ET65 at 65 watts and a 16 ohm WGS Green Beret at 25 watts. Will the 8 ohm ET65 be louder than the 16 ohm Green Beret wired parallel?

It may be, but I don't think it will be that noticable. Try it and see how it works, you have nothing to lose!

Also, total power handling of the cab in this config will be 50W.

Dom

 

[nopicknick]

Thanks Dom I appreciate it......I'll let you know how it works out once the speaker arrives.

 

[dodger916]

Speakers are a 8 ohm WGS ET65 at 65 watts and a 16 ohm WGS Green Beret at 25 watts. Will the 8 ohm ET65 be louder than the 16 ohm Green Beret wired parallel?

It may be, but I don't think it will be that noticable. Try it and see how it works, you have nothing to lose!

Also, total power handling of the cab in this config will be 50W.

Dom

How did you calculate that, Dom?

 

[domct203]

Speakers are a 8 ohm WGS ET65 at 65 watts and a 16 ohm WGS Green Beret at 25 watts. Will the 8 ohm ET65 be louder than the 16 ohm Green Beret wired parallel?

It may be, but I don't think it will be that noticable. Try it and see how it works, you have nothing to lose!

Also, total power handling of the cab in this config will be 50W.

Dom

How did you calculate that, Dom?

General rule is 2 X the lowest wattage speaker (for a 2-speaker cab).

Dom

 

[boogiemon]

anybody know what happens if you connect a 8ohm speaker to the 8ohm jack & another 8ohm speaker to one of the 4ohm jacks? i'm guessing this is bad, but don't know why.

tia

 

[domct203]

anybody know what happens if you connect a 8ohm speaker to the 8ohm jack & another 8ohm speaker to one of the 4ohm jacks? i'm guessing this is bad, but don't know why.

tia

This will present a lower then expected impedence through the Output Transformer, putting extra stress on the powertubes wearing them out alot quicker. In less robust amps this could lead to OT or other component failure.

It would be best to run two 8 ohm cabs in the 4 ohm jacks. The 4 ohm jacks are wired in parallel. Two 8 ohm loads in parallel is 4 ohms total.

Hope this helps!

Dom

 

[boogiemon]

yeah, i know what the recommended config is but i'm wondering about the OT seeing a load on both taps.

thnx,
j

anybody know what happens if you connect a 8ohm speaker to the 8ohm jack & another 8ohm speaker to one of the 4ohm jacks? i'm guessing this is bad, but don't know why.

tia

This will present a lower then expected impedence through the Output Transformer, putting extra stress on the powertubes wearing them out alot quicker. In less robust amps this could lead to OT or other component failure.

It would be best to run two 8 ohm cabs in the 4 ohm jacks. The 4 ohm jacks are wired in parallel. Two 8 ohm loads in parallel is 4 ohms total.

Hope this helps!

Dom

 

[94Tremoverb]

Speakers are a 8 ohm WGS ET65 at 65 watts and a 16 ohm WGS Green Beret at 25 watts. Will the 8 ohm ET65 be louder than the 16 ohm Green Beret wired parallel?

It depends on the sensitivity of the two speakers.

The 65 will be getting twice the power that the 25 gets - the power splits in inverse proportion to the impedances if they're in parallel, so the 8-ohm speaker gets 2/3 of the total and the 16-ohm gets 1/3 - so if the 65 is also more sensitive, it will sound a lot louder. If it's the same, or best of all if it's slightly less, there will be less difference or it may even sound more balanced.

The power handling is improved like this too - it's not 50W, it's 75W. The total cabinet handling is still dependent on the lower-rated speaker, but since only 1/3 of the power goes to it, you can then go to three times the rating of it not twice. (As long as you don't go above 1.5 times the higher speaker rating as well, which in this case you don't.)

In other words, it's complicated! If you don't know how to do all the math, it's best to ask someone who can first.


This is all with the two speakers in parallel by the way - in the same mono cab, or both connected to the 4-ohm jacks. If you run the speakers with the 16 from the 8-ohm jack and the 8 from the 4-ohm jack, that's then balanced and each speaker gets the same amount of power.

You shouldn't run 8 from 8 and 4 from 4 at the same time because the *total* is then a low mismatch and will stress the tubes. Worse, it will put more load on the 4-ohm tap of the output transformer because it's a *tap* on the full 8-ohm winding not a separate winding. This means that it has to carry the full current for both loads, which will stress it. I've never seen a transformer blown like this but it's a possibility.