Gregm said:
I'd agree with that, when I went box to dipole the difference was not really slap you in the face. It was after time and long periods of listening to music I knew well that I realised how more natural and less coloured an open baffle really is.
On the other end of the spectrum you can also get used to boxiness, really because you have not heard an open baffle, but until you do you dont fully realise what your missing. Lots of box speakers dont sound obviously boxy, seeming to add nothing to the sound. Boxy is a weird word to use also, when I thought of boxy, before I tried OB, I thought of when certain frequencies are excited the box barks at the listener, some boxed speakers dont do this becaues they are designed well, so I thought they were not boxy. However they were, boxy is what a box sounds like, not obvious colouration mind you but remove the box and you'll know what i mean.
If you A/B the same drivers in a well made box vs dipole the difference isn't subtle as long as low end extension is addressed.
I did that with some Adire HE8.1's which are a nice little bookshelf speaker. I needed some help in the bass department because the emminence beta8cx has a high Qts, so I put 4 6" TV speakers in a W baffle in the bottom with amazing difference and I just slapped a coil I already had to roll off the bottom. With more tweaking it will just get better. My 8yr old daughter asked me last night why one sounded so much better than the other. I have one of each running while I finish the 2nd dipole.
I think all you'd have to do is put dipoles where people can listen and compare them to boxes and they would be easy to sell. There's no reason they should be restricted to high-end and DIY projects. All you need is an interesting compact design and since so many are including subs in their systems for HT setups it makes the size even more flexible for an economical dipole.
I did that with some Adire HE8.1's which are a nice little bookshelf speaker. I needed some help in the bass department because the emminence beta8cx has a high Qts, so I put 4 6" TV speakers in a W baffle in the bottom with amazing difference and I just slapped a coil I already had to roll off the bottom. With more tweaking it will just get better. My 8yr old daughter asked me last night why one sounded so much better than the other. I have one of each running while I finish the 2nd dipole.
I think all you'd have to do is put dipoles where people can listen and compare them to boxes and they would be easy to sell. There's no reason they should be restricted to high-end and DIY projects. All you need is an interesting compact design and since so many are including subs in their systems for HT setups it makes the size even more flexible for an economical dipole.
I finished my dipoles a couple of hours ago and hooked them up for some listening.
First impression: Horrible!!! It sounded very thin and the sound stage was totally out of hand.
Things got *slightly* better after I discovered that I had forgot to connect the right channels midrange driver
Actually, things got MUCH better
Not bad at all, I must say!
I will post pictures and more detailed reports of the sound as soon as I get any.
First impression: Horrible!!! It sounded very thin and the sound stage was totally out of hand.
Things got *slightly* better after I discovered that I had forgot to connect the right channels midrange driver
Actually, things got MUCH better
Not bad at all, I must say!
I will post pictures and more detailed reports of the sound as soon as I get any.
Glad to hear it Glad you sorted out the problem with the mid driver. Although you've solved the problem have you got any compensation on the mid driver or even the bass drivers for open baffle roll off?? If the the frequency response is rolling off due to cancellation this could add to the "thin" sound. Mine sounded thin without compensation.
Glad you sorted out the problem with the mid driver. Although you've solved the problem have you got any compensation on the mid driver or even the bass drivers for open baffle roll off?? If the the frequency response is rolling off due to cancellation this could add to the "thin" sound. Mine sounded thin without compensation.
All this talk of OB is getting me excited to try something but I want to start small and cheap. I have some questions:
1) Is it necessary to have an active EQ and separate amps? I'd rather drive them with my Pioneer Elite receiver.
2) I built a set of HT speakers using Axon 6S3 mids and Axon T1S tweeters from www.zalytron.com (the budget kit- 3 GermanMTM's and German 2 Way for surrounds)
I'd like to experiment OB with these drivers. I have 8 6S3's and 4 T1S's to my disposal for two front speakers. If someone can be kind enough to design an OB out of these, I'd like to try.
Thanks,
Shajan
PS:
FYI: These will be used primarily for movies. I have a HSU VTF-2 sub. I'm most interested in soundstage and detail.
1) Is it necessary to have an active EQ and separate amps? I'd rather drive them with my Pioneer Elite receiver.
2) I built a set of HT speakers using Axon 6S3 mids and Axon T1S tweeters from www.zalytron.com (the budget kit- 3 GermanMTM's and German 2 Way for surrounds)
I'd like to experiment OB with these drivers. I have 8 6S3's and 4 T1S's to my disposal for two front speakers. If someone can be kind enough to design an OB out of these, I'd like to try.
Thanks,
Shajan
PS:
FYI: These will be used primarily for movies. I have a HSU VTF-2 sub. I'm most interested in soundstage and detail.
shajan said:
No, especially since you have a sub. People use EQ primarily to get more bass response.
With a Qts of .47 , although not ideal, those mids should work pretty well on OB, since you have a sub to help support the bass.
Do you have an adjustable cutoff for your sub? Where your sub cuts off will guide you on how wide to make your baffle. Here's a link for baffle width vs low frequecy roll off point. http://www.angelfire.com/electronic/DIY/OB-Speaker-concept-1b.html
Re design: That's the cool thing about OB, the sky is the limit. Many use flat baffles, but I like to sweep back the side "wings" to narrow the front profile and add stability since I have kids. Experiment with cardboard or what I use is the posterboard with the styrofoam center for a little more stability. Add duct tape to hold the drivers in place and you can be listening to a test baffle in 5 minutes. Figure out a design you like the sound of before building your permanent baffle.
You already have drivers and a crossover, so you could take the drivers out. Extend their wires from the current cab which you could use to support the test baffle and literally be listening withing 10-15 minutes. Only do one at first, so you can A/B or L/R the box with the OB.
PS- Off center mounting on the test baffle is best. Also since it's multiple drivers you might want 2 different sized trapezoid shaped wings on the sides.
Happy experimenting!
Thanks John.
Currently I let my receiver send everything under 80hz to the sub and the rest to the mains. My sub does have an independent crossover control which I'm not using at the moment.
According to the first graph from your link, I'll need a baffle size of 45" to go down to 70hz. Am I reading that right?
Is an MTM configuration suitable for OB? How about an array with 4 mids and 2 tweets?
I've never heard an OB but I'm just itching to start doing some mods
Currently I let my receiver send everything under 80hz to the sub and the rest to the mains. My sub does have an independent crossover control which I'm not using at the moment.
According to the first graph from your link, I'll need a baffle size of 45" to go down to 70hz. Am I reading that right?
Is an MTM configuration suitable for OB? How about an array with 4 mids and 2 tweets?
I've never heard an OB but I'm just itching to start doing some mods
According to that graph yes, that's where the OB bass rolloff will start, but those mids you have already start rolling off on their own below 200hz, so that might be too low of a target. Definitely experiment with cardboard or something first and see at what level you can best integrate your sub.
I'm sure MTM is fine. 4 may become problematic because the line array effect will come into play giving you a narrow vertical plain for listening. Test it to see what you like best.
If you have your computer connected to your system, I highly recommend buying a tone generator. I've found it my most useful tool in speaker projects. I paid $20 to download one online. It's the TTG Test Tone Generator.
I'm sure MTM is fine. 4 may become problematic because the line array effect will come into play giving you a narrow vertical plain for listening. Test it to see what you like best.
If you have your computer connected to your system, I highly recommend buying a tone generator. I've found it my most useful tool in speaker projects. I paid $20 to download one online. It's the TTG Test Tone Generator.
I've been listening to my dipoles for about 2 months now (Orion clones, in looks only) and I have to agree that you do get used to the boxiness of traditional baffles. After my first 'wow these sound great' impressions of the dipoles, I couldn't help feeling that something was missing. Yesterday I made a quick sealed box and mounted one of the woofers in it just for a comparison. With the sealed box connected I initially didn’t think there was much difference between them, it wasn't until I reconnected the dipole bass that I realised how much better these things sound, the bass is very precise and controlled, were as the sealed sounded muffled and delayed. In my opinion what I was actually missing was the boxiness sound that I’d grown up with and become accustomed to and when it was gone there is an empty space left and I was missing something that wasn’t supposed to be there in the first place.
Given a choice of the two alignments, dipoles win hands down.
Morning All,
My trouble with all this is that I haven't seen some nice "forumlae" or spreadsheets as the Boxed blokes have which give me guidance on where to start regarding speaker parameters and baffle sizes.
I made my first open baffle woofer two weeks ago using a subwoofer driver which was going into my subwoofer project box (admittedly chosen for making into a box) - I put it into a bedroom door which was lying in the garage. I was disappointed that it made almost no sound at all, and was alarmed at the uncontrolled excursions it made around some apparent "resonances" in the system (in the 20 - 40 Hz range).
All very spooky. Experiment stopped post-haste.
Are there any "end-user", not-quite-so-esoteric programs or spreadsheets to help me on the way?
Regards,
GB
parameters of that driver:
Qts 0.35
Qms 8.709
Qes 0.364
Vas 230 litres
Fs 21.3
Sd 494cm^2
nominal diameter 30 cm Dd 25cm
My trouble with all this is that I haven't seen some nice "forumlae" or spreadsheets as the Boxed blokes have which give me guidance on where to start regarding speaker parameters and baffle sizes.
I made my first open baffle woofer two weeks ago using a subwoofer driver which was going into my subwoofer project box (admittedly chosen for making into a box) - I put it into a bedroom door which was lying in the garage. I was disappointed that it made almost no sound at all, and was alarmed at the uncontrolled excursions it made around some apparent "resonances" in the system (in the 20 - 40 Hz range).
All very spooky. Experiment stopped post-haste.
Are there any "end-user", not-quite-so-esoteric programs or spreadsheets to help me on the way?
Regards,
GB
parameters of that driver:
Qts 0.35
Qms 8.709
Qes 0.364
Vas 230 litres
Fs 21.3
Sd 494cm^2
nominal diameter 30 cm Dd 25cm
The usual minimum recommended Qts for OB use is .50, although some use very low Qts drivers and equalization of offset the bass rolloff. I've read that Qts in the .75-1.00 range is ideal, but some use drivers with Qts well above 1.00 .
Here's a graph that shows the frequency vs baffle width. Below those frequencies the bass response rolls off at 6db/octave. http://www.angelfire.com/electronic/DIY/OB-Speaker-concept-1b.html
On OB drivers have a tendency to have peak in response at their resonant frequency Fs. Some alignments try to take advantage of this peak and have it coincide with the baffle size rolloff to obtain a flatter response with lower extension.
Off center driver mounting is recommended.
One nice thing about OB's is that you can make test baffles out of cardboard and quickly hear the results of a design and modify it in a matter of minutes with virtually no cost. It's much more fliexible in that you don't have to calculate volumes, port lengths, etc. You can make crossover changes without taking anything apart or unsealing anything. You are also quite unrestricted on baffle material and shape, so be creative and have fun with it.
Here's a graph that shows the frequency vs baffle width. Below those frequencies the bass response rolls off at 6db/octave. http://www.angelfire.com/electronic/DIY/OB-Speaker-concept-1b.html
On OB drivers have a tendency to have peak in response at their resonant frequency Fs. Some alignments try to take advantage of this peak and have it coincide with the baffle size rolloff to obtain a flatter response with lower extension.
Off center driver mounting is recommended.
One nice thing about OB's is that you can make test baffles out of cardboard and quickly hear the results of a design and modify it in a matter of minutes with virtually no cost. It's much more fliexible in that you don't have to calculate volumes, port lengths, etc. You can make crossover changes without taking anything apart or unsealing anything. You are also quite unrestricted on baffle material and shape, so be creative and have fun with it.
fdegrove said:Hi,
They really work well with ribbon tweeters.
I recall SD Acoustics using OBs in MTM configuration with a leaf tweeter in the middle plus a ported woofer for the lows.
It really worked very well; fast, hardly any colouration to speak of and very good imaging.
Cheers,
I'm using Pioneer/TAD beryllium ribbons. They are quite good. I have been considering the MTM configuration lately. The problem being I would need to pad down the mids. Thats something I've worked really hard to avoid up to now. Do you think the trade off would be worth it? I could wind up some non inductive silver resistors for the job.
I'm also considering switching to a W frame dipole like this one from S. Linkwitz.
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