Can You Help? How Would I Wire Up This Cab??

[boneyguy]

I'm thinking of making a 3x10 cab for my old Traynor YSR-1 head. The cab would need to be 8ohms. What ohmage of speakers would I need and how would I wire it to wind up to be 8ohms overall? Is it even possible?

[Joe-Bob]

IIRC, 3 32 ohm 10s wired parallel. The Jensen Mod 10-50 is available in 8, 16, and 32 ohm models.

[Billm]

Three 32's is 10 ohms; close enough.

Two 8's in series is 16 ohms. Add one 16 in parallel and you're back to 8.

[boneyguy]

Originally Posted by Joe-Bob

IIRC, 3 32 ohm 10s wired parallel. The Jensen Mod 10-50 is available in 8, 16, and 32 ohm models.

Originally Posted by Billm

Three 32's is 10 ohms; close enough.

Two 8's in series is 16 ohms. Add one in parallel and you're back to 8.

Cool. Thanks guys.

Hey Billm, could you post a diagram (or a link) of how to do the 2 in series, 1 in parallel. Please.

Thanks again guys.

[Joe-Bob]

Originally Posted by Billm

Two 8's in series is 16 ohms. Add one 16 in parallel and you're back to 8.

Yes, but I wonder if that will distribute the workload evenly?

[Billm]

[Billm]

The workload distribution should be fairly even. The same amount of current flows through the single- and double-speaker branches. Series speakers always sound a bit different from parallel, which might be a good thing tone-wise. 16- and 8-ohm speakers of the same model often sound a little different anyway.

[Greg Seaman]

Why not go for 4-10's? The cabinet would be only slightly larger. Then you could use identical speakers and not have to worry about differences in tone or power handling from speaker to speaker. Conventional series/parallel wiring schemes could then be used.

For 3-10's I like Bill M's idea. Bill knows his stuff!

[robt57]

http://www.duncanamps.com/zips/speaker5.xls

This excel sheet/book will tell you about every possible combination, and how the wattage will be distributed to each driver

[boneyguy]

Originally Posted by Joe-Bob

Yes, but I wonder if that will distribute the workload evenly?

Originally Posted by Billm

The workload distribution should be fairly even. The same amount of current flows through the single- and double-speaker branches. Series speakers always sound a bit different from parallel, which might be a good thing tone-wise. 16- and 8-ohm speakers of the same model often sound a little different anyway.

Originally Posted by robt57

http://www.duncanamps.com/zips/speaker5.xls

This excel sheet/book will tell you about every possible combination, and how the wattage will be distributed to each driver

Thanks for the responses guys.

In terms of the workload distribution in Billm's wiring diagram (according to the Excel sheet that robt57 linked to) if I was using a 100 watt amp then each of the 8ohm speakers in series would be handling 25 watts and the one 16ohm speaker wired in parallel would be handling 50 watts.

Is that an okay distribution of power?

Originally Posted by Greg Seaman

Why not go for 4-10's? The cabinet would be only slightly larger. Then you could use identical speakers and not have to worry about differences in tone or power handling from speaker to speaker. Conventional series/parallel wiring schemes could then be used.

For 3-10's I like Bill M's idea. Bill knows his stuff!

I'd like to use my existing cab that I built a while back. I don't really want to build another cab.

[Billm]

As long as the 16 ohm speaker can handle 50 watts, you're fine. If you play with heavy distortion, however, your speakers should be rated for at least twice the clean output power of the amp.

Who the heck uses a 100 watt amp anymore?

[boneyguy]

Originally Posted by Billm

As long as the 16 ohm speaker can handle 50 watts, you're fine. If you play with heavy distortion, however, your speakers should be rated for at least twice the clean output power of the amp.

Who the heck uses a 100 watt amp anymore?

My amp is actually about 45 watts, give or take. I was just using the ready made 100 watt example from the Excel sheet.

So using 45 watts the calcualtor tells me the distribution is 11.25 watts each for the series 8 ohms and 22.5 for the single 16 ohm.


So then Bill, those numbers just mean the peak watts that the speakers would be asked to handle, correct? It's not like the single 16 ohm speaker is being given more of a workload, so to speak. In otherwords the volume output that would be coming from each of the 3 speakers would be equal. Correct? I think I already know the answer but it's nice to have it confirmed by someone who is actually knowledgeable about these things.

Thanks for all your help Bill.

[Billm]

The volume should be fairly equal.

[boneyguy]

Originally Posted by Billm

The volume should be fairly equal.

How is it that they would all not be equal volume Bill? Can you elaborate please. Thanks.

[robt57]

Originally Posted by boneyguy

How is it that they would all not be equal volume Bill? Can you elaborate please. Thanks.

Because twice the cone area/vol on the two 8s as the 16, it should be pretty well balanced IMO


Not considering resonance of the drivers, or rather assuming similar resonance...

[Billm]

As I mentioned earlier, manufacturers sometimes list different efficiency numbers for the same speaker model but with different impedance. It stands to reason: If you add more wire, you need less magnet or larger gap or some other adjustment to keep the speaker's action relatively the same.

In any event, they'll be close enough, within a couple of dB. And that's all that matters.

[Greg Seaman]

A Fender Vibro-King has three 8 ohm 10's wired in parallel producing a 2.667 ohm load. How does the amp match it? The output transformer is tapped to accommodate a 2 ohm load (close enough). You could upgrade the output transformer and add an impedance switch. This is a bit more complicated but would make the amp much more flexible. What do you think Bill?