BillFitzmaurice.info

Rick James wrote:Why didn't you just build SLAs?

I have the SLA Pros and T24. I have run into a need for small set of satellite speakers, so I'm trying to build a small set of line arrays that will fit in a tight area for both set up and transportation.

Using one output channel of your amp for SLA pro's, and one for your T24, obviously you can't run in stereo.
I think one SLA pro rather than 2 would provide a good output balance with 1 x T24.
Personally, I would add another T24 (daisy chained) before I added another SLA pro...

johns811 wrote:

NukePooch wrote:

johns811 wrote:I'm attempting to make 2 small line arrays, they are 4" wide and 36" tall, Each will have 6 4 ohm full range drivers.I was hoping to have the option connecting speaker 1 to speaker 2, OR also be able to connect them each off their own channel....So think I got the wiring down to make a 6 ohm cabinet.

I'm missing something here...how do you take one 4 ohm driver and end up with a 6 ohm cabinet?

6 o

I'm trying to wire 6 4ohm drivers, the way I understand it with 3 sets of 2 the math would be 4ohm * (3/2) which would be 6 ohm cabinet.

Okay, my mistake. I thought you were putting one driver per box, 6 boxes per side...then trying to wire the whole mess externally.

It's not 3 sets of 2, it's 2 sets of 3...As Tom Smit said, you want to wire banks of three drivers in series (12 ohms), then parallel two banks to get a 6 ohm cabinet load. There is no 4 ohm measurement anywhere.

I'd just run one cab per amp channel...they're not gonna take much power, so you don't need a big amp. If you absolutely need to run off of one channel, then parallel the boxes, and make sure you've got an amp that'll run 2 ohms. (the load will be 3 ohms, but amps are generally rated 2,4,8 ohms.)

is this correct to get 6 ohm using 4 ohm driver? (wiring)

Also I found this diagram on the web which I think is the same thing. (wiring 2)

johns811 wrote:is this correct to get 6 ohm using 4 ohm driver? (wiring)

Also I found this diagram on the web which I think is the same thing. (wiring 2)

(edited)
Ugh...I was wrong , Grant's right. Both pictures will end up with the same result though they're wired differently....

NukePooch wrote:

johns811 wrote:is this correct to get 6 ohm using 4 ohm driver? (wiring)

Also I found this diagram on the web which I think is the same thing. (wiring 2)

The first one is correct. Two banks of three drivers per bank.

The second picture is incorrect, three banks of two drivers per bank. This will likely let the smoke out of your amp. (or it will just shut down)

The second one is from a set of Bill's plans I think you will find.

And it doesn't matter, either way is correct.

In example 1
3 x 4 ohms in series is twelve and 2 banks of those in parallel = 6 ohms

In example 2:
2 x 4 ohms in parallel is 2 ohms, add 2 ohms for the next pair, and again add 2 ohms for the third pair because you connected the three pairs with serial wiring, and you get 6 ohms...

NukePooch wrote:

johns811 wrote:is this correct to get 6 ohm using 4 ohm driver? (wiring)

Also I found this diagram on the web which I think is the same thing. (wiring 2)

The first one is correct. Two banks of three drivers per bank.

The second picture is incorrect, three banks of two drivers per bank. This will likely let the smoke out of your amp. (or it will just shut down)

It looks the same to me, just drawn a different way. Thanks for the feedback.

Grant Bunter wrote:

NukePooch wrote:

johns811 wrote:is this correct to get 6 ohm using 4 ohm driver? (wiring)

Also I found this diagram on the web which I think is the same thing. (wiring 2)

The first one is correct. Two banks of three drivers per bank.

The second picture is incorrect, three banks of two drivers per bank. This will likely let the smoke out of your amp. (or it will just shut down)

The second one is from a set of Bill's plans I think you will find.

And it doesn't matter, either way is correct.

In example 1
3 x 4 ohms in series is twelve and 2 banks of those in parallel = 6 ohms

In example 2:
2 x 4 ohms in parallel is 2 ohms, add 2 ohms for the next pair, and again add 2 ohms for the third pair because you connected the three pairs with serial wiring, and you get 6 ohms...

Thank you, yes the 2nd drawing in the style Bill uses, I can understand it better for some reason.

It's always good to understand.

Following the plans is always good too

I think I got the wiring correct, the volt meter said 6.5 ohms. They sound really good, should meet my needs for a small speaker that is light and easy to haul around. Total cost was about $100.

Measuring resistance across the drivers does not equal the impedance of the drivers. 2 different specs that behave and affect the cab differently.

In your picture, it appears that your drivers are spaced quite a bit apart, nearly a driver's width. This is going to cause a lot of comb-filtering. If you are happy, so be it.

Not sure how I ended up spacing them that far apart. The cabs cost $8 each and this was sort of an experiment. What is the effect of comb filtering?

johns811 wrote:Not sure how I ended up spacing them that far apart. The cabs cost $8 each and this was sort of an experiment. What is the effect of comb filtering?

I don't think it will be all that bad since it's vertical and not horizontal.

DJPhatman wrote:Measuring resistance across the drivers does not equal the impedance of the drivers. 2 different specs that behave and affect the cab differently.

In your picture, it appears that your drivers are spaced quite a bit apart, nearly a driver's width. This is going to cause a lot of comb-filtering. If you are happy, so be it.

You'll never hear it once you're about two feet from the speaker. PA line arrays have that much space between cabs easily.