Dayton IB385 vs Alpha's

espressif · « **on:** 13 Feb 2016, 10:32 pm »

Hi all,

I have an opportunity to get 2 IB385. I wonder if their much heavier cones (200 gr vs 60 gr for Alpha's ultra light ones) will result in a somewhat slow bass and worst watch with my full ranges.

My current target is about improving low range definition and maybe get a better low end extension, but I don't care for excursion limit, power handling and shaking the house...

My current setup:
Open baffles with Alpha 15A (MiniDSP and 150 w solid state) and Mark Audio Alpair 12P (SE 2A3).

Should I pass on these and get something like Deltalite? What do you think? Thanks for your input,

FullRangeMan · « **Reply #1 on:** 13 Feb 2016, 10:43 pm »

Heavy cones are a prob for small amps.
Its know that the ideal QTS is 0.9, considering the Alpha QTS=1:26(bass too soft).

The dayton ib385 is awful for OB, sensitivity is low 88dB, QTS 0,6 dont works as OB, its suggested to Infinite Baffle(sealed box);
http://www.parts-express.com/dayton-audio-ib385-8-15-infinite-baffle-subwoofer--295-455

espressif · « **Reply #2 on:** 13 Feb 2016, 11:21 pm »

Thank you for your input Fullrangeman,

Maybe I wasn't clear enough, but this is an active setup and the Alphas are connected to a very beefy Kyocera Power amp (around 200 w).

JohnH12 · « **Reply #3 on:** 14 Feb 2016, 03:49 am »

You can get lower frequency response with the IB385 over the Alpha. Active, I think the choice is easy, IB385. What size is your baffle?

espressif · « **Reply #4 on:** 14 Feb 2016, 03:54 pm »

It is 20" wide by 40". I have a +6dB low shelf filter.

espressif · « **Reply #5 on:** 14 Feb 2016, 03:55 pm »

My fear is that heavier cone will make the transition with the Alpair light cone very audible.

JohnH12 · « **Reply #6 on:** 14 Feb 2016, 10:37 pm »

Here are a few baffle (not driver responses) The IB will get your low FR. Look at the data under the Equivalent Circular baffle.

If you can cross under 500Hz you should be OK. I'm thinking if this is the 3 inch Alpair it's too small for the IB.

espressif · « **Reply #7 on:** 14 Feb 2016, 10:52 pm »

John, that is really enlightening ! Thanks a lot.

No problem, cause I actually use the 8" Alpair. No passive high level xover, only high-pass at 130 Hz inside the 2A3 amp. Acoustic roll off of the full range begin at 160 Hz...

nicoch · « **Reply #8 on:** 17 Feb 2016, 02:44 pm »

really wrong ob speakers this dayton ,you want one AE 18OB or try beta in H baffle
you use one alpha ?

JohnH12 · « **Reply #9 on:** 18 Feb 2016, 04:18 am »

It's only wrong if going passive. Low FS, high xmax, large SD. Volume displacement is going to give a good spl.

Linkwitz has a decent spread sheet where you can compare drivers spl_max1.xls

Note that this spreadsheet is 4pi space so depending on your configuration you need to add 6 dB. You can do the same with ABC Dipole posted above but it's a bit less intuitive.

nicoch · « **Reply #10 on:** 18 Feb 2016, 10:00 am »

sure ?

JohnH12 · « **Reply #11 on:** 18 Feb 2016, 11:54 am »

Your graph is correct. Now boost the low end with a DSP. The alpha runs out of x-max at 91 db and 40 hz while the IB gets 102 db at 40 hz. The graph below shows the alpha only. The equivalent circular baffle data shows the max SPL for the alpha. The previous post shows the IB. If you can't find spl_max1 and are interested I'll post that when I'm back Friday.

nicoch · « **Reply #12 on:** 18 Feb 2016, 01:18 pm »

what ? at 91db 40hz the alpha is at 1w no need boost
you want put a 14db boost on dayton ? you know the watt needed ?! the thermal compression and distortion ?!

OB_Newbie · « **Reply #13 on:** 18 Feb 2016, 08:26 pm »

I believe John is correct. After boosting LF, the Dayton IB385 would be an excellent choice and have been thinking about that driver for use in OB for some time now.

Remember, Martin has stated that that the Alpha is not as efficient as the specs state...91dB for the Alpha, IIRC, so the 88dB of the Dayton isn't much off the mark. The extra Xmax will indeed allow it to go lower than the Alpha.

Not a knock on the Alpha in any way... I love Eminence products myself and think highly of the Alpha; especially for a passive OB system as Martin has so elegantly designed and has to be thee most copied OB format!

Kind regards to all,
Rich

nicoch · « **Reply #14 on:** 18 Feb 2016, 10:25 pm »

Not correct at 50hz the alpha is 95db the dayton 87db that's 8db down.....
plus the dayton don't go lower , at 85db he is at 41hz the alpha 33hz !
sure alpha is not perfect I think we must use a pair for side....

JohnH12 · « **Reply #15 on:** 19 Feb 2016, 01:11 am »

Here's Linkwitz spreadsheet.

nicoch · « **Reply #16 on:** 19 Feb 2016, 01:03 pm »

john you miss the point
Is clear the with more xmax we can push more spl ...but at cost of lot distortion for sure !!
we cannot ignore thermal compression too, 10w on alpha=70w on dayton
I use a 93db 8" in OB with 300b never see move too much! I have never see a 15" move in normal domestic hifi use , espressif dont have this problem
alpha go lower than dayton that's quite important , at85db D.is at 41hz, alpha 33hz

nicoch · « **Reply #17 on:** 19 Feb 2016, 01:05 pm »

espressif you could add a beta in parallel....

JohnH12 · « **Reply #18 on:** 20 Feb 2016, 04:08 am »

I believe the point of this discussion is there are two types of OB systems active and passive. We should consider the driver with respect to the application. Linkwitz has many interesting articles for those who would like to investigate further.

I also find this discussion a bit ironic as I prefer to design passive OB systems.

nicoch · « **Reply #19 on:** 20 Feb 2016, 10:35 am »

HI John fine I take your point,