[Fjendbo]

Hi,

New here!

I am sorry if a similar topic has been made many, many times. Feel free to link to any relevant topics.

I currently have planned 2xBG Neo8 and 1xBG Neo3 pr. side and would like to use them with 2x15" in OB. The speakers will be crossed actively with a MiniDSP OpenDRC-DA8 and powered by an 8 channel amplifier. The woofers will need to be available in Europe and my budget is about DKK 1000, EUR 135, USD 145 pr. woofer. Cheaper will do no harm

I've read that the Neo8 will perform best if crossed around 700Hz so the 15" woofer will need to perform fairly well to around 900-1000Hz, I assume, but at the same time perform in the low end. The candidates I have come across are:

PureAudioProject OB-A15se (pushing the budget)
Monacor SP-382PA (Fs 25Hz)
Omnes Audio OBW 15PA

I'm sure I have missed some candidates.

Thank you!

[AJinFLA]

https://www.intertechnik.com/Shop/Loudspeakers/Dayton/Dayton-Subwoofer/_-DCS385-4_1768,en,7053,135363
9.3mm xmax, strong motor with copper shorting ring for lower inductance, distortion and better control over long strokes.
Cone is well behaved to 900hz (look at impedance) https://www.parts-express.com/dayton-audio-dcs385-4-15-classic-subwoofer-4-ohm--295-206
You would want to run pair is series unless you're using pro or potent home amp. Daytons QC is good, not problem doing so.
Yes, I have used dipole before. 
Mechanical/aerodynamic noise is "ok", most likely as good/better than your candidates. I would recommend stiffening frame with some bracing.
Best of luck!

cheers,

AJ

[nicoch]

 OB-A15se do really good on OB.....

[Fjendbo]

AJ, Thank you for the recommendation. I have actually been looking at that Dayton driver a while ago, but I thought Qts was too low requiring a too much EQ/power.

Regarding the amplifier, I have a NuForce MCA-20 8 channel 150watt/8 ohm, 278watt/4ohm per channel. I know it's nothing fancy but I like the small package and flexibility of 8 channels - and I found it used for less than 1/4 of the new price.

Maybe the low Fs compensates for the higher roll-off/Qts?

nicoch, good to hear!
Do you have personal experience with the driver? And even better, have you had the chance to compare them to other drivers often used in OB?

[nicoch]

is the upgrade of  alpha eminence  .... a real winner respect all the speakers in this thread
only the neo will be better that is a ob version of deltalite 2515 eminence

[AJinFLA]

AJ, Thank you for the recommendation. I have actually been looking at that Dayton driver a while ago, but I thought Qts was too low requiring a too much EQ/power.

No. High Qts makes for easier passive OB bass, but your system will be active. As such you can shift poles and create whatever desired LF alignment you wish. I hope you are planning to measure!
Start here: http://www.audiocircle.com/index.php?topic=149607.0
http://www.linkwitzlab.com/faq.htm#Q34
You don't need over boost the low end. Depending on your woofer/baffle response, you might only need 4-6db boost in the low end below certain frequency, 4-6db cut above this to flatten the response. The advantage of a strong motor woofer with shorting rings like the Dayton, is more low LF output (below 30hz) and greater linearity/lower distortion without exceeding xmax during LF transient peaks. It really comes down to how low you want to go, at what clean volumes.

cheers,

AJ

[nicoch]

6 to 10db  is a lot power under 100hz....

[JohnH12]

+1 AJ

Also note that a flat baffle for the woofer(s) will allow you to reach the BG without the resonance issues of an H or W frame woofer.

[Fjendbo]

Thank you for input!

My plan is a flat baffle with some kind of fabric back cover to increase WAF. The boss wasn't too happy with the idea of visible drivers on the back - fair enough.
The drivers will be placed (as it is right now) with the 15" woofers above each other with Neo8-Neo3-Neo8 placed next to them to keep the height of the speaker below 1 meter, with a slight tilt to aim the Neo drivers at the listening position. And I will be looking to stiffening the frame, as well as using multilayer front baffle with absorption between layers (rubber cork and/or "soft glue") and woofer magnet support.

I'm only able to place the speakers maximum approx. 75cm/30 inches from the back wall. Will that have any impact on driver selection as in will a lower Q woofer require even more EQ to compensate for the distance to the back wall opposed to a higher Q woofer?
And with the EQ of a low Q woofer won't I see sensitivity go down quite a bit, or shouldn't that concern me at all? I usually don't play very loud.

Also, I'm having this idea that the Dayton won't do as well in the midrange compared to OB-A15se for example due to heavier cone and higher LE. At the cost of low-end extension, of course. Or shouldn't that concern me either?

What about beaming? Large woofer, high crossover point.

A lot of questions, sorry!

If anyone else has anything to add, please do so

[nicoch]

a point to start : OB live in diy's world  thanks to Alpha and Beta Eminence !
700Hz is good for 15"

btw take a look for Slob by Nelson Pass the improved version ,the link is the old ones
www.firstwatt.com/pdf/art_slob.pdf

[JohnR]

The drivers will be placed (as it is right now) with the 15" woofers above each other with Neo8-Neo3-Neo8 placed next to them to keep the height of the speaker below 1 meter

I would suggest considering using a single 15 with the Neos above it, and then separate subwoofers.

I'm only able to place the speakers maximum approx. 75cm/30 inches from the back wall. Will that have any impact on driver selection as in will a lower Q woofer require even more EQ to compensate for the distance to the back wall opposed to a higher Q woofer?

My "rule of thumb" for bass response is a meter - see Figure 4 here: http://www.hifizine.com/2012/03/on-dipole-subwoofer-placement/

However the effect on midrange might be greater.

What about beaming? Large woofer, high crossover point.

You will need to measure it on your baffle. At 700 Hz you are (probably) above the dipole peak - which has a way of messing everything up.

If you haven't already bought the drivers, I would consider a single Neo10 instead of the two Neo8s.

[JohnR]

The boss wasn't too happy with the idea of visible drivers on the back - fair enough.

The boss has a good point actually... some of my drivers look much the worse for having dust collecting on them for years, a well done system would (I imagine) have a fabric dust cover that could be removed and washed.

 

[Fjendbo]

JohnR, thank you for input.

My initial idea was actually 4x8" + separate subwoofer in a closed box per side, but the idea with 4 "boxes" was ruled out 

Here is a quick sketch of how I imagined it:


She would rather have two larger speakers. A quick sketch of how that could look here below:



I also think it looks better to get the drivers covered up as long as the shallow (right word?) look remains.


Thank you for the link - will give it a good read later. And I will move the speakers away from the wall each week - just a little bit. I'm sure she won't notice

I already have the Neo8's and 3's. The Neo drivers are almost unobtainable in Europe and fairly expensive from the US (and Europe as well). I bought my 6 units used for EUR 260/USD 280 in total. I would prefer the Neo10 but that's currently not a possibility.

Regarding woofer/Neo placement, I also considered doing as the Oido Audio 12 speaker, but the Neo8/3 section would be at least 50 cm long looking kind of funny
http://www.oidoaudio.com/

[JohnR]

Hey, sounds like you got a great deal

I'm sure you can appreciate that it's hard for people on a forum to help you negotiate WAF constraints (too many variables and unknowns)

[AJinFLA]

And with the EQ of a low Q woofer won't I see sensitivity go down quite a bit, or shouldn't that concern me at all? I usually don't play very loud.

All your questions would be answered if you modeled your baffle design with both drivers in the free programs linked. You have more than enough power to exceed xmax of both drivers at very low frequencies, though one will reach xmax before the other, a situation usually undesired. YMMV.

Also, I'm having this idea that the Dayton won't do as well in the midrange compared to OB-A15se for example due to heavier cone and higher LE.

Those are ideas based on intuition and inexperience. Again, look at the inductive rise in the impedance measurement and resonances. Used below 700hz (your target), both drivers will be fine. The heavier Dayton cone extends lower and is better damped, so no severe breakup requiring a notch filter one octave above XO, like the other driver. No free lunch. Both drivers will work, though at 700hz, there will be significant asymmetry in the front/rear response due to the rear basket/motor structure.

At the cost of low-end extension, of course. Or shouldn't that concern me either?

That, only you can answer.

What about beaming? Large woofer, high crossover point.

See above. There are sometimes benefits to having a more cardioid response in many rooms, which is what you will have below 700hz down to around 300hz.
Measurements will tell you all you need to know  .
Actually, if you are limited by height/budget to a single 15, you may want to consider going full cardioid in the bass with what you have drawn. Though a sigle 15 dipole may just be enough if you listen at modest levels and not too much pipe organ.

cheers,

AJ

[JohnR]

If you don't mind my saying, low end extension is not really a valid concept - it really depends on what you are aiming for but the low end "carries" everything else. So it's not "extension" per se, it's either there (in that "Hercules" role), or not. Anyway that's my experience and why I suggest separate subs

[Fjendbo]

Yes, WAF will be my headache - or challenge

All your questions would be answered if you modeled your baffle design with both drivers in the free programs linked.

I have tried doing a quick simulation in Basta - I'm new to it so please advise me if something looks off.



I will end up with a sensitivity of about 79,5 dB 2.83v/1m if I'm correct. 85,5 dB with EQ sound alright. But maybe there's some additional baffle loss and possible room gain that Basta! can't include? Where would realistic sensitivity figures end up?

I would really like to stay with dipole bass - I've read so much good about it
And though I don't listen to pipe organ music yet (maybe really good speakers will make me appreciate it), I don't like to have that limit hanging over me. I think I will stick with 2x15".

If you don't mind my saying, low end extension is not really a valid concept - it really depends on what you are aiming for but the low end "carries" everything else. So it's not "extension" per se, it's either there (in that "Hercules" role), or not. Anyway that's my experience and why I suggest separate subs

I will try getting my terms right, thanks . And you are right, it's either there or not. I'm not very used to talk or write about speakers in English so I'm still learning on that front as well.
Again, seperate subs will mean 4 "boxes" which didn't receive the "approved" stamp . And it would probably also mean no OB bass?

[JohnR]

Actually that would have been me not getting my terms right Not really sure how to explain it, to be honest.

I would really like to stay with dipole bass - I've read so much good about it
And though I don't listen to pipe organ music yet (maybe really good speakers will make me appreciate it), I don't like to have that limit hanging over me. I think I will stick with 2x15".

You have to be realistic... I suppose that's part of what I mean... if you are keen on designing a system that produces 16 Hz tones (at any reasonable volume), OB isn't a good place to start.
 

Again, seperate subs will mean 4 "boxes" which didn't receive the "approved" stamp . And it would probably also mean no OB bass?

No, you can have separate OB subs. Moving them close to the listening position will make them a lot more effective.

However, there's a point where you have to build (and measure) something to learn

[Fjendbo]

You have to be realistic... I suppose that's part of what I mean... if you are keen on designing a system that produces 16 Hz tones (at any reasonable volume), OB isn't a good place to start.

I have no intention to reach 16 Hz . I'm happy with 30 Hz.

No, you can have separate OB subs. Moving them close to the listening position will make them a lot more effective.

However, there's a point where you have to build (and measure) something to learn

And I will measure.
I have been offered 4 15" woofers used in the Dali S1.5 subwoofer (+ 12 other drivers (Infinity, TVM, BG)) at a reasonable price (EUR 200) which I will have a look at this weekend. Being unable to get any driver info from Dali, I have been able to borrow DATS V2 and will measure the drivers. That just won't tell me Xmax. I have read 10mm on a forum but cannot get it confirmed by any.

[Fjendbo]

I got the Dali drivers and measurements looks quite alright, I believe.