I need site members help in building an open baffle speaker with 2 Eminence Beta 15a woofers (45-3.7k hz), Tang Band W1808 (45-20K hz) and MiniDSP 2x4 HD active Crossover. I have the following questions:
Greg
- What would you use as the MiniDSP crossover setting for the Beta 15a woofers?
- What would you use as the MiniDSP crossover setting for the Tang Band W1808
- Any additional comments in setting up the MiniDSP would be greatly appreciated (first time using an active crossover).
- Would you wire the 2 woofers in series or parallel?
- I have two OddWatt Mono Tube Amps (45 watts each) and Hafler 200 solid state stereo amp. I was planning to use the tube amps for Tang Band speakers and Halter for woofers. Is this a good configuration.
Greg
Why did you choose drivers that overlap in the lower mids? That seems like a
squandering of bandwidth....
squandering of bandwidth....
What are you trying to say??
The Eminence will not sound very good playing up high and the Tangband won´t go deep on a baffle.
Driver choice seems absolutely reasonable enough for a 2-way OB.
And of course you will need "overlap"! You don´t have to be a speaker design expert to know that.
Greg,
did you google your choice of drivers? There seems to be lots of projects around these drivers and you can probably catch lots of valuable information from these.
Example:
asr
You could try and simulate your baffle with these drivers (Basta or similar) and see what you can get, then measure and modify your simulated crossover values.
You can also just build a baffle (similar to other projects like the PAP whose dimensions can be found), measure and modify DSP settings.
I´d probably start with a crossover around 350-400Hz and see what I´d get.
Do you have access to a microphone?
These are some very poor choices for an open baffle system. Are you trying to copy a Pure Audio Project design? Do you have any prior experience with OB speakers and crossovers? Have you modeled or can you measure the driver responses?
Siegfried Linkwitz was probably the most knowledgeable on all things Open Baffle.
I'd recommend a deep dive on his website as a great start on your journey.
https://www.linkwitzlab.com/
I'd recommend a deep dive on his website as a great start on your journey.
https://www.linkwitzlab.com/
Good enough for lots of DIY projects (incl. Martin King who IMHO chose even less ideal drivers with the tiny FF85) and commercial manufacturers like PAP & Spatial with many fans amongst the DIY crowd.
I´d repeat that every speaker is a compromise and a 2-way OB is just another.
You are no doubt an OB expert Charlie but this is a DIY site and a place to encourage people to tackle totally sane projects.
Of course a 4-way OB is more ideal but not easy to tackle for a newbie and quite naturally so more expensive too.
I think it's pretty clear what I mean, but not for you.
Others have already interpreted it correctly.
Now, if the OP already has THOSE speakers in his possession and is hoping for guidance on how to tamper with his Mini DSP, we look forward to your revealing insight.
Academia50, thanks for your input. I choice the design from the the following site https://ikeahackers.net/2012/02/numerar-loudspeakers.html. It is a three way OB. I spoke with Parts Express and the recommended the tweeter since the tweeter from the link was not available. I spoke with GR Research about designing a XO for me put he said I had the wrong tweeter. So I decided to go with a two way OB with active crossover. I realize that will to lap on the crossover but did. not know how much. A few years ago I spoke with Pure Audio Project and they said they did not feel a tweeter was necessary with the Tang Band and Eminence woofersI am a novice in speaker building. I appreciate any help. Greg
Joensd thanks for responding to my request. I am a novice and the is my first speaker build. I got my driver choice from the following link https://ikeahackers.net/2012/02/numerar-loudspeakers.html. Thanks for suggestion on overlap and crossover suggestion at 350-400Hz. How much overlap would you recommend. Had a three way setup put decided to go with 2 way after talking with PAP and GR Research. I have tried to find resources for designing the active crossover even contact in MiniDSP and looking at their website but it did not help. So far my research I cannot find any link that describes setting an active crossover. Can you please advise what you mean by "ASR"? I purchase a mic and stand but have not used yet.
Attached are pictures of my current OB. Thank you for your kind help and comments.
Attachments
CharlieLaub thank you for your response. I based my design on the following link. https://ikeahackers.net/2012/02/numerar-loudspeakers.html. Also obtained recommendation from Part Express for drivers for the OB. I am a novice and and do not have experience with OB speakers and crossovers. I have rebuilt a couple of crossovers and bought a kit for small 2-way box speaker and made the crossover based on their design. I did have a 3 way OB but decided to go with 2 way based on discussions with PAP and GR Research. I do have the miniDSP software, mic and a stand. Any help and suggestions would be greatly appreciated. Thanks for your help. Greg
Joensd thanks for your input. This is my first diy OB speaker and I am trying to learn. The following are the OB speakers I made. I tried a 3-way but after discussions with PAP and GR Research I decided to go with 2-way. Pictures are attached of my try in building my first OB speaker. What would be your suggestion for a 4-way speaker? Any suggestions are help would be greatly appreciated. Greg
Attachments
In my mind, OB/dipole systems have an informal division: large baffle and small/no baffle.
The PAP type systems are the "large baffle" type. These use the large baffle to increase the distance between front and rear and reduce low frequency losses. The main benefit of this kind of system is that you need only a few drivers/bands, since each driver can operate over a relatively wide band and dipole losses are lower. The large baffle blocks some rear radiation from reaching the listener, and it is the reflection off of the front wall that can give a dipole system a very 3D soundstage. With a large baffle, and with drivers that in some part of their band do not radiate to the rear, the system is more like an "inifinite baffle" closed box in some ways. But many successful systems have been built this way, and it is certainly valid to do that.
On the other extreme are systems with small (e.g. Linkwitz LX521) or no (100% nude driver) baffle dipole systems. With no baffle present, there are higher losses for the drivers used in the lower part of their passbands. This typically means that more drivers/bands are required and each driver is best when restricted to about 2 octaves only. The performance requirements for drivers are also higher in terms of distortion and other characteristics. Here it is best to use DSP and multiple amp channels are needed. The minimal baffle allows the front wall reflection to reach the listener, so the rear radiation is just as important as the front to keep the tonal balance correct. Also, the front wall should allow for a broadband reflection and use of adsorption materials should be minimized - a larger, more live room is best.
It seems like you want to try the "large baffle" system. I suggest as a first step to become familiar with what the driver responses will look like on the baffle. I urge you to do some modeling. A good program for that is theEdge by Tolvan Data. You can start by modeling the baffle with your two woofers on it, and then you will see the high frequency limitations and the low frequency losses you can expect. This will also help you to figure out where to cross over to your other driver. Martin King designs systems like this, and I recommend that you look at some of his designs. He is also on Facebook and runs an open baffle group there that you might join so you can ask questions to OB specific DIYers.
Very nice speakers you have there!
I don´t have any suggestions as I never digged deep enough into the topic of OB.
It is quite involving to build a 4-way anyway, OB especially so.
Charlie already gave reasons for a 4-way: Minimal baffle systems have advantages but can´t be used over a wide bandwidth and thus you will end up with 4-ways.
You will find lots of posts on the subject if you want. Just dig a little.
Especially "OB experts" like Rudolf, Juhazi, John K. and many others have written a lot about OB:
Aino (just one of many examples)
And of course the great Linkwitz and his creations. (RIP; see his website)