Dual Opposing Driver as Full(er) Range?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi Everyone,

First time poster and long time lurker...

I have always had an interest in audio and now have a keen interest in making my own speaker cabinet.

Now I have looked at posts like:

http://www.diyaudio.com/forums/mult...-driver-opposing-magnet-dipole-configure.html

and:

http://www.diyaudio.com/forums/subwoofers/164690-dual-opposing-drivers-cancellation-issues.html

But they are not answering my question directly and my poor overloaded (with new found knowledge) mind is struggling a little with the idea.

I would like to create a full range cabinet which is not isobarik, and I guess the correct term is bipole? This is with drivers opposing each other (wired in the same polarity) so that they get the vibration cancellation effect and still retain the increased SPL of the dual drivers. The issue comes in with the following questions:

1. Can I use these in a full range setup?

2. If not, at what frequency will they start to phase cancel, that is if they do cancel at all and is this related to the effective driver spacing between them? i.e. quarter wavelength or half/full etc?

3.With regards to enclosure as well, what would be the difference between having each driver with its own enclosure space (i.e. essentially two cabinets back to back but joined as such) vs a shared space?

4. With regards to using a mids driver if the phase cancellation issue is present, what is a good rule of thumb for power rating of mid/high drivers to woofer drivers as they require more power to obtain that low end thump than the mid to high drivers?

I apologise if this is a strange post and if I have oversimplified it, but I have read so much and I am starting to go round in circles with the sheer amount of information out there.
 

GM

Member
Joined 2003
Correct.

1. Yes.

2. This gets a bit complex, but if you don't like the added ambiance of all the extra delayed reflections from the rear driver, then roll if off with a hi-pass filter. This is called a 1.5 system.

3. Basically nothing, but the divider braces the cab, which is a good thing, so the technically preferred construction.

4. This too gets a bit complex, but ideally you use the same amp model when multi-amping except for separate sub systems typically limited to <100 Hz.

Understood and made much worse by all the [not so] well meaning 'misunderstandings' to outright 'floobydust' littering the net.

Maybe some links you missed: https://www.google.com/search?q=Jim...rome..69i57.8550j0j4&sourceid=chrome&ie=UTF-8

GM
 
Hi Shaun,

Yeah looks like you're overloaded a bit mate ;)

If you're just talking about making a full range bipole like this

DIY Sealed Bipole Speaker Project with Fostex FE127E Driver

Then you'll be fine.

Bipole need room to breath though, wouldn't be placing them close to the wall.

I'd put them in a shared enclosure, couple the magnets together as best you can.

Correct.

1. Yes.

2. This gets a bit complex, but if you don't like the added ambiance of all the extra delayed reflections from the rear driver, then roll if off with a hi-pass filter. This is called a 1.5 system.

3. Basically nothing, but the divider braces the cab, which is a good thing, so the technically preferred construction.

4. This too gets a bit complex, but ideally you use the same amp model when multi-amping except for separate sub systems typically limited to <100 Hz.

Understood and made much worse by all the [not so] well meaning 'misunderstandings' to outright 'floobydust' littering the net.

Maybe some links you missed: https://www.google.com/search?q=Jim...rome..69i57.8550j0j4&sourceid=chrome&ie=UTF-8

GM

Thanks, both these posts have restored my hope in the build again! :cheers:

I found this document though which talks about the cancellation issue, would a 4dB dip be a problem? The author does not seem to think so.

http://www.creativesound.ca/pdf/OffsetBipolarMLTL.pdf

He said this:

"While I
did notice that there was a dip of 4 dB in the on-axis response in the 400 to 500 Hz range because of the wraparound of energy from the rear driver to the front driver when the front to rear spacing between the drivers was a half wavelength, I could not hear an appreciable degradation to the overall performance of these speakers. "
 
Hi Everyone,

First time poster and long time lurker...

I have always had an interest in audio and now have a keen interest in making my own speaker cabinet.

Welcome to DIYAudio Anonymous as an active poster :D

We're all adicts here :cheers:

I started my DIY activities with a full range speaker. I enjoyed it hugely and learned a lot. The results weren't very good, I discovered full range drivers are too bright, too sharp and make my ears hurt. I started with the Fostex FE127 and it was awful (to my ears). Anyhow, it's a great hobby. My advice is 1)to invest in some good tools - I didn't do that and struggled more than I should have. And be anal about safety in using them. 2) start building something very soon or you'll end up going mad as your brain tries to absorb decades of collective knowledge through that information fire hose, the internet.

I believe I would have been happier if I had started out by copying Dave's Tysen speaker design (named after his son I believe). It has two things that I believe you will like. It has opposing drivers in a push-push and it uses that for the lower frequencies where vibrations are more of an issue. The higher frequencies are handled separately by a full range driver that is small enough to push most annoying cone resonances above the 'presence' region where my ears are more sensitive.

Thread here: http://www.diyaudio.com/forums/full-range/144099-thread-tysen-variations-fast.html

Edit: found a sketch of the design (copyright Dave)
 

Attachments

  • Tysen-V2-extents.gif
    Tysen-V2-extents.gif
    25.3 KB · Views: 234
Last edited:
+1, my first was an oval mobile audio driver stuck in a cardboard Kleenex box just because it had a 'close enough' size oval punch out. Got two [Cub] Scout badges for it. ;) Used it hooked up to a tube mono AM car radio/6 V battery in my shop till '75.

+1 on some 'flavor' of FAST bipole, best of both 'worlds', 'FR' with real bass without a huge BLH.

GM
 
Bipole need room to breath though, wouldn't be placing them close to the wall.
Every speaker needs air, well, it's the basic!

Regarding the bipole, probably :eek: it's not a good solution because the final mixing ( we're talking about audio reproduction, two tracks trackin' ) on the media it's done mostly with a forward emission in front of the listener, same as the caption, which is mostly done with the mic(s) in front of the venue.
 
Thanks Everyone,

All your posts have had some form of valid input and I will definitely get this project underway soon.

I work away and currently have been designing the speaker in the evenings so hence the mild overthinking of all the aspects. 2 and a half weeks left and then the project starts!

I have the design pretty much done. I have done the driver selection, WinISD work and the cabinet dimensions are almost there.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.