Two pair in parallel - 16 ohm and 8 ohm

[oldman55]

Given same efficiency, would the 8 ohm have more "volume" and would you run them on the 8 or 16 ohm tap?
Or better to add an 8 ohm resistor to the one pair and put on the 8 ohm tap?

 

[onplane]

Given same efficiency, would the 8 ohm have more "volume" and would you run them on the 8 or 16 ohm tap?
Or better to add an 8 ohm resistor to the one pair and put on the 8 ohm tap?

Your request is most confusing. What do you want to do?

If you have two sets of 8 ohm speakers and you want to run them in parallel, you must select the 4 ohm tap (if indeed you have a tube amp, which isn't terribly clear from your post).

Regards,
Jerry

PS: To prevent responses off target, you should post pics of your amp and the amp's back panel.

 

[oldman55]

One pair of speakers are 16 ohm, the other set are 8 ohm. Both supposingly 92db. Wanting to connect the two pair to one tube amp. The amps all have 4, 8 and 16 ohm speaker taps.
Dont know how much power I will be needing until I test so dont know which amp I will using. Guess it is a theoretical question.

 

[onplane]

One pair of speakers are 16 ohm, the other set are 8 ohm. Both supposingly 92db. Wanting to connect the two pair to one tube amp. The amps all have 4, 8 and 16 ohm speaker taps.
Dont know how much power I will be needing until I test so dont know which amp I will using. Guess it is a theoretical question.

OK! That's a lot clearer. The answer is still the same - 4 ohm tap.

The combined impedance is 5.3 ohms which is closer to 4 than 8.

One thing you should understand is that speaker sensitivities are all suspect. Chances are one set will dominate the other. You'll undoubtedly get better sound by running a separate amp for each speaker set.

Regards,
Jerry

 

[oldman55]

Thanks. In theory, would the 8 ohm get more current and more volume?

 

[drumbum]

Plenty of 8ohm speakers dcr at 5 something ohm.

 

[onplane]

Thanks. In theory, would the 8 ohm get more current and more volume?

In theory, both should put out 92db at one watt. For an 8 ohm speaker, one watt is 2.82 volts. For a 16 ohm speaker, one watt is achieved at 4 volts.

So in theory you'll get to one watt on the 8 ohm long before you do on the 16 ohm, so it should be louder. Again, this goes back to my earlier statement about sensitivity ratings. You just can't put a lot of faith in them.

Regards,
Jerry

 

[onplane]

Thanks. In theory, would the 8 ohm get more current and more volume?

I just had another though about getting your speakers to put out similar sound. Specifically, the issue is could you connect the 16 ohm set to the 16 ohm tap and the other set to the 8 ohm tap?

Turns out this is NOT recommended at all. You must connect to the tube amp taps in such away that the net impedance determines which tap to use. Any other way is just asking for trouble.

Regards,
Jerry

 

[oldman55]

Guess putting L pad on the 8 ohm may be an option and monitor the the impedance of the combined load?

 

[bowtie427ss]

The combined impedance is 5.3 ohms which is closed to 4 than 8.

While this is true, it's best to try that load on both(NOT at the same time) 4 and 8 ohm taps and go with which sounds best.

 

[Katalyst]

Some answers could be found here . The tube tap issues would be a separate issue. http://speakerimpedance.co.uk/?act=two_parallel&page=calculator

 

[bowtie427ss]

Some answers could be found here . The tube tap issues would be a separate issue. http://speakerimpedance.co.uk/?act=two_parallel&page=calculator

That's a handy calculator for us lazy academics, i like it! Thanks for posting.