# Looking for help with OBs



## krips (Sep 7, 2008)

I want to pull the trigger and get dipoles in my living room. They would be used for ht/gaming. If you think the design is good, this is what I am thinking of getting. Of course other options/opinions will be greatfully considered.

Per Speaker
4x Dayton RS225-4
2x RS28A (One mounted on rear of baffle)

How does this driver compare to the RS180 in terms of distortion? They are similar in price and the RS225s displace a fair bit more for the money. Total cost of drivers would be ~$770 CDN + taxes and shipping.

Sketchup - 'Cabinet' Drawings

Dimentions - ~ 63'Hx13"Wx6"D with 1.5" deep driver cutouts. This leaves 2.25" past the front and the back of 'H frame'. I'm not sure how this effects the higher frequency dispersion etc...

The Edge - Predicted Dipole Response


WinISD 






Any comments will be appreciated .


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## jackfish (Dec 27, 2006)

Your model shows a larger baffle (68"x25") than your cabinet designs (63"x13"). For proper frequency response in an open baffle design you can't shortchange the baffle.


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## krips (Sep 7, 2008)

That was after I added 1/2 the distance on both sides that the wave would have to travel with the 6" 'h frame wings'...is that not the correct approach for modeling?


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## Anthony (Oct 5, 2006)

That's the approach I used in OB design. It works to a point, but you are unfolding the baffle now and not a true flat or H baffle, so the responses won't be perfect (but close)

Also, check your mic position, it looks low. That will affect some of the higher end effects as the path lengths differ.

I played around a while with the RS225s. Good tight low end, fairly wide range. NASTY breakup mode at 1.8kHz. So if you are doing a 2 way, you need to cross at least an octave below that, preferably more, which puts a tremendous requirement on your tweeter (or moves you to a 3 way system). The BG Neo8 is up to the task, albeit with a really weird top octave response (which doesn't actually sound that bad).

The 180s won't give you the LF extension (always a major design point in an OB speaker) but I imagine their breakup mode is higher, which might let you get away with a higher tweeter crossover point. I haven't played with them, though, so I can't say for sure. Maybe Zaph Audio tested them (www.zaphaudio.com)?

Sadly, my project is on hold pending a move. Just last night I boxed up all my RS225s, Neo3s, Neo8's, and B3N drivers. That box was really heavy.  But I remember enough of my build that I can probably help out, so keep us posted.

Just be prepared to prototype, build, measure, and modify (then repeat). Seems to be the only way to make these OB's work right.

Good luck.


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## krips (Sep 7, 2008)

A DCX2496, Behringer 802 Mixer, and ECM8000 Mic would be helpful for design (this is my first Design IY)....no?


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## Anthony (Oct 5, 2006)

I did not use the DCX (old fashioned way, passive crossovers and lots of tweaking), but the 802 and ECM8000 are a good combo. I assume you have a good sound card that can take the line in from the 802?

But yes, measurements are key (and be prepared to make hundreds of them  )


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## krips (Sep 7, 2008)

IIRC I opted for no sound card in my current PC, just using the onboard. Could be wrong though. I can pick up a sound card though. Whatever I need to get this hobby up and running full steam. Is there a 'go to' soundcard? Or does it just need some sort of line-in?


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## Anthony (Oct 5, 2006)

I have an M-Audio external one for my laptop, but there's a whole forum in the Room EQ Wizard (REW) section of the site devoted to hardware and setup of REW. Lots of threads regarding good soundcards (and the ones people have problems with).


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## krips (Sep 7, 2008)

I'm building an order at PE...looking like RS28/RS225 with either the TB W4-1337 or the RS150 for mids in a WWMTMWW setup. What's everyones vote on the mid choice? Both seem pretty popular.


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## Anthony (Oct 5, 2006)

I like the 225's and could sell you my extras, but they are the -8's and you are in Canada (extra shipping cost, duty, etc, -- probably cheaper to get them from PE  )

I tried a WMTMW arrangement with the W3 Tang Band Bamboo and it sounded really good. The open back makes it easier to install (no need to chamfer an obscene amount of material from behind to open up for the back wave). I was impressed. No direct experience with the W4 or the titanium lines, though.

The RS150's are 6" drivers, a bit big for mids, unless you need them to play really low it might be tougher to mate them with the tweeter (i.e. the tweeter might not go low enough). The RS225's will play high enough to get them handed over to a 4" or 3" mid driver. They are all good drivers though, so you probably will still be happy with the results either way.

The only other thing I would worry about is efficiencies. It's easy to pad down the mid and tweeter, almost impossible to do so with the woofer. An old dipole trick is to use a really large iron core inductor on the woofer crossover to cut some efficiency and start the crossover frequency well below the intended frequency. With the right size baffle (and baffle hump), the combination matches efficiencies and flattens the woofer response (while keeping the overall crossover point to the mids). Of course, if you go active, this isn't as much of a problem, but you still need a shelving filter to handle the baffle hump.

Good luck and keep us posted!


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## Superstatic (May 8, 2009)

It looks very nice, have you started building? Are you using passive filters? 


regards, Jonas


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## krips (Sep 7, 2008)

Hello Jonas. Welcome to HTS . I have not started yet, I have yet to order the drivers! Soon though I hope. My behringer DCX2496 is ordered though (which I beleive answers your second question). I've never designed a crossover so I thought the 2496 would be a good place to start. I will be sure to update this when notable progress is made .


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## krips (Sep 7, 2008)

http://www.usspeaker.com/ciare 6.38ndw-1.htm

Perhaps there is some funky measuring procedures going on, but the inductance on this driver is stupidly low! Would it make a very good mid in a 3 way? The Seas W22 is a bit out of my range and rather insensitive.


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## 1Michael (Nov 2, 2006)

I am no expert on OB but the ones I did build sounded much better with the bass drivers as close to the ground as possible. Of course your mileage might vary.


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## krips (Sep 7, 2008)

Probably due to the floor reinforcing the bass frequencies I'm guessing? I will keep this in mind.


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## mongo22 (Dec 2, 2007)

I would google "Hawthorne Audio" for some open baffle drivers before you buy anything. They come with passive crossovers built specifically for the drivers, all you need to do is build a simple baffle. Ive had mine ( a pair of 15" Silver Iris) for over a year now and they are absolutely amazing. You can get more info on open baffle speakers over on their forum as well.

-andy


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## mayhem13 (Feb 2, 2008)

Hey Krips, like the OB idea, just not the driver choices as has been pointed out with the RS225 breakup. PE has a great buyour deal on the 6.5" Peerless Nomex woofers that can easily do 2.5khz with four and are very efficient and handle gobs of power. To keep C to C spacing down they have truncated frames and would be a perfect match to the smaller SB Acoustics SB29 which is an excellent tweeter. I'm doing some high efficiency work with it now and different waveguides and i'm amazed at how low this can go. I've got one paired to an Eminence Deltalight 2510 10" woofer in a ported two way with a 10" qsc waveguide crossed LR2 at 1.6khz and i'm stunned at what it can handle. Given the buyout price of those peerless nomex's, they're hard to pass up. You'll have to cross high with OB though.


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## Jason Schultz (Jul 31, 2007)

Hi Krips. seems OB is popular at the moment. I'm in the middle of designing an OB with 4" TB mids (w4 616 SA) and vifa D27 tweeters. and a 12 inch paper woofer. WMTM. I'm going to use the woofer in a U frame though for stronger bass. I haven't done any testing yet. Hope to post when under way.


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## krips (Sep 7, 2008)

I was looking at all the HDS buyout drivers at PE. They always seem to be getting different ones...does anyone know if this will be a continuous thing? Also, I look forward to your OB project. Please keep me updated!


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## krips (Sep 7, 2008)

Apparently the Neo3s and 6.5" peerless HDS drivers will be showing up tomorrow, along with a mic and preamp. The DCX2496 already came. Once that gets here, I just need to figure out what to order for cables and it's go time!  Oh, and a soundcard I suppose.


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## Anthony (Oct 5, 2006)

What cables are you concerned about? 

For everything other than S-video and HDMI, I usually make my own. Canare, F-Conn, and Neutrik make very good quality ends for just about anything you'd need. 

Let me know and I (we) can narrow down some recommendations.

Good luck! Exciting to get all the toys, isn't it?


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## brianpowers27 (Sep 7, 2008)

I have done several OB experiments with rs225. I don't think it sounds great past 1khz and lacks the extension for impressive bass. It sounds very good as the woofer in a monopole but not so much in a dipole. The driver's q is too low to operate efficiently in an open air setup.


I hate to be a naysayer. I just can't see the reason for building this as a 2 way. I would strongly suggest using something to this effect.

Eminence Alpha 15" ob woofer (near the floor in a u or h frame.) 
Dayton rs150 x2 mids crossed at 1.8khz
Dayton rs28 x2









Also.. Consider that the dipole directivity is dependent on baffle width. When you can use the driver in a frequency range below the dipole peak, directivity is improved.


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## krips (Sep 7, 2008)

Anthony, I'll be needing XLR to RCAs for my receiver-->DCX2496-->gainclones (75% done those). I don't really have speaker cables right now, but I'm happy with my OFC wire for the moment .
Brian, I gave strong consideration to the dual RS28 idea, but at somewhere between double and triple the cost of the Neo3 I thought this was a more economical option. The Neo3 seems to be loved by many.
I have given up on my hopes of a two way. The Fi IB318 and Eminence Alpha 15A are both ones I'm looking at for the low end. It seems that my two 6.5" peerless HDSs will be able to cross somewhere in the 150-200hz range if I so desire.  Still waiting on fed-ex!


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## Anthony (Oct 5, 2006)

If you don't mind soldering, Neutrik makes great XLR and RCA ends. Get some two conductor wire (or three or four -- I use Canare Star Quad microphone cable) and solder away. There are several wiring diagrams on the internet for how to make an XLR unbalanced to RCA connection. I always forget the pins and have to look it up each time (or look at a cable I already did :duh: )


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