Recomendation to use one coil only !?!?

bes51659 · 10-15-2009, 03:06 PM

I am considering to buy a DLS Iridium 10 inch for a 22l sealed enclosure.

For some reason they recommend that I only use one of the 4 ohm coils for that setup. Why not use both? I can see that Q values change for 2 coils. Howcome?

soundman98 · 10-15-2009, 04:03 PM

depends on who you talk to. to some shops, this is a huge no-no, but i really don't see the dissadvantage to it-- you will get a 4 ohm load, and the speaker is powered... i always kind of thought that dvc subs are to give more options for amp configurations.

bes51659 · 10-15-2009, 05:12 PM

Will the speaker still be 500W RMS? I guess that depends on how the coils are winded. Are they normally interleaved so that heat is transported just as well with one coil as with two?

Is the only "pricetag" for using a single coil that the magnetic gap could have been made smaller without the deadweigth of the second coil, giving better dB/W ratio?

But I still not understand what difference it makes using one coil instead of two, apart from the obvious reason. Optimizing the load for the amp(s).

soundman98 · 10-16-2009, 11:55 PM

The coil that you hook up to should deffinatly still take what the manufactuers specs say it does. I think that you might have a point about the second coil being 'dead wheight', but really don't know how much it could realistly affect the sound. I doubt it would be enough to audibly hear a difference though. As long as the maker is who is suggesting using one coil, I wouldn't worry about it too much-from what I've read, dls makes some great speakers, so I highly doubt that they would overlook a detail like that

bes51659 · 10-20-2009, 07:13 AM

I have just been told by DLS that using just one coil does not affect the power handling. I still get 500W!

My guess is that this is because power handling in a sealed box is affected by how small the box is (small box will reduce movement of cone and therefore increase electrical loss = reduce max power handling), mechanical damage due to exceeding x-max (no problem in not too big sealed boxes) heat dissipation from coil (can be the same with one or two coils). All of these are more or less the same with one or two coils

But there is also mechanical stress to coil due to magnetic force. The coil will be tared apart with to much current. Not a limiting factor in the DLS element, if I can believe DLS themselves.

(Obviously the signal frequency and clipping etc has an effect, but as a comparison that does not matter. One thing I will never accept is the recommendations to use stronger amps than the speaker can handle because they are less likely to clipp. So the speaker break before clipping. What is the advantage of that?)

But I have not an answer to why they recommend using just one coil. In what way can that make the speaker work better in a certain box config?

Thoughts on this?

bes51659 · 10-22-2009, 05:47 PM

Quote: Originally Posted by bes51659

But I have not an answer to why they recommend using just one coil. In what way can that make the speaker work better in a certain box config?

Thoughts on this?

I think I am confused at a higher level now, and that the answer to quoted question is:
"Lower Qts makes the speaker more suitable for the ported box that has a higher Q by itself. Single coil, higher Q, fits better in a sealed box with a lower Q". Am I correct?

What I think I've learned is that Qts (total) changes with single coil because Qes (electrical) changes. Qes is given by Re/BL². Single coil 0.01403 and dual coil 0.00844. Now, I guess that I have lost a constant somewhere, because the relation between my numbers and DLS numbers (0.87 as single and 0.54 in dual) match. But why is Re not 1.6 ohm in parallell when the coils are 3.2 ohms on the DLS Iridium 10i?

Secondly I can't understand how qms (q mechanical) could be affected by how the coils were connected. Qms on DLS with one coil is 2.84, and with both coils 3.44. Why is Qms different?

BL (flux * wire length in cap) on the DLS iridium 10i is higher with one coil than with both. 15.1 instead of 14.6 with coils in parallell. Why is BL not the same, given that the coils are in parallell? More or less like the gauge of the wires suddently dubbled.

soundman98 · 10-22-2009, 06:56 PM

You might want to take this over to a car audio forum- I am horrible with exact numbers like this, and judging the the minimal responses to your questions, so are a lot of other members here.

bes51659 · 10-23-2009, 06:30 AM

Ok :-)
I've found one that seems good and started a thread there.

I have got an answer from DLS that seems to answer all my q's once I get the time to look into it. I even got a testreport on the speaker.

From what I understand with that element I get better fequency responce curve with one coil, and I get the same power ratio and everything but the price I have to pay is 3dB (half the) sensitivity...

Thanks for your help and interest, soundman.

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