8'' two-way any reason why not?

[dthomas]

Re: 8'' two-way any reason why not?

So if we're lucky enough to find an 8'' woofer that can extend to about 2K, that would be good?

Yeah the Vifa P21 woofers PE still has some work well for this application. I think North still has some of their tweeters that were on "last call" left. You can cross them down around 1400Hz. Also I have heard the Seas P22RNX can work quite well crossed in th 1500 to 1800Hz range.

2000Hz would be about the limit and lower will be better. I remember the AR 8" two ways from the mid 70's as being a very nice all around loudspeaker. Reasonably compact and full range. I think they were ARs hard to believe that was 30 years ago.

Unfortunately there are not any budget class 8" woofers that fit the bill that I am aware of.

[robert]

Re: 8'' two-way any reason why not?

I like the waveguide idea and may investicate that

[Shonver]

Re: 8'' two-way any reason why not?

I like the waveguide idea and may investicate that

I think that Zaph has some info on waveguides-on-tweeters, and others have likewise published some info. See also DIYaudio.com forums.

[djg]

Re: 8'' two-way any reason why not?

Gowa, do you remember your old thread at HT guide asking about the seas poly 8" on sale at Madisound? A member posted a design made from a concrete form tube and a PE horn lens. I made a couple of those and am very happy using them as surrounds. They give a very spacious surround effect in my small living room.

[Æ]

Re: 8'' two-way any reason why not?

Decades ago, 8" 2ways were fairly common... and many sounded real nice. Problem is, not many drivers are made similar to those types... which often had better upper midrange, but less low bass response/output.
I'm not a fan of ear-level tweeters, but a 8" 2way might benefit from the woofer being above the tweeter, but the xover might be a pain--Haven't studied passive filters yet, but sure one would be common... active would need delay.
Thinking about a future 8" 2way myself, and if it goes forward, I'll get a 24db active filter with delay. I'd go sealed, and might try a 3/4" tweeter to match the narrower dispersion at xover.

GC

A 3/4" tweeter will have better dispersion than a 1" tweeter in the highest of frequencies. As the frequency goes down any dome tweeters dispersion WIDENS rather than narrows! If you wanted to match the narrow dispersion of a woofer at crossover, then technically you would need a tweeter the same diameter as the woofer!
A 3/4" tweeter is a poorer choice to match up with an 8" woofer simply because most 3/4" tweeters cannot be crossed over low enough.
Better off to use something even larger than 1" for instance the Morel MDT33 (33mm) 1.3"

[jcapodieci]

Re: 8'' two-way any reason why not?

There is a dirty little secret about small woofers. To get any bass they need a long excursion. If highs, mids and lows are mixed in the same woofer, the lows cause the “Doppler Effect” on the mids and more so on the highs. When the cone is moving 10 to 20 mm to produce good bass it will modulate or cause tonal shifts in higher frequencies produced by it at the same time. The Doppler Effect can be reduced in a 2-way by setting a low crossover frequency, perhaps 1KHz or lower and use a broad band horn for the mids to highs. Below are some suggestions from the PE catalog as a start. Good luck.

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-235

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-315

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-306

Coil and Cap:

http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=255-426&DID=7

Two of the following caps:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=027-932

To really feal the bass, this option be attached to the floor or bottom of a chair:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=299-028

Here's one site to calculate your own values:

http://www.the12volt.com/caraudio/crosscalc.asp

[robert]

Re: 8'' two-way any reason why not?

So, another bennie is that there is less cone excursion for a given SPL, since the driver is larger.

Bill Fitzmaurice is right about using a pair of smaller drivers in an MMT or an MTM. Radiating area for a pair of 7's will be larger than for a single 8. However, unless you are using some buyout stuff or the rare pair of 4-Ohm drivers that let you series connect, you will end up with a 4 Ohm load, something some people wouldn't want. That said, well done MTM's and MMT's are great, though with the MMT you are building a design with full baffle step. Another consideration...

I think the simplicity of the 8" 2-way attracts me most, you get a 2-driver system that is in some ways comparable to a smaller 3-way. Every design has compromises of some sort, be they size/cost/complexity/F3/etc. and you just have to decide what you are willing to trade.

Robert

[Æ]

Re: 8'' two-way any reason why not?

My favorite 8" two way:

http://www.geezas.net/kls9/main.html

[Guest]

Re: 8'' two-way any reason why not?

A 3/4" tweeter will have better dispersion than a 1" tweeter in the highest of frequencies. As the frequency goes down any dome tweeters dispersion WIDENS rather than narrows! If you wanted to match the narrow dispersion of a woofer at crossover, then technically you would need a tweeter the same diameter as the woofer!
A 3/4" tweeter is a poorer choice to match up with an 8" woofer simply because most 3/4" tweeters cannot be crossed over low enough.
Better off to use something even larger than 1" for instance the Morel MDT33 (33mm) 1.3"

I was thinking about trying (used, sale, etc) one of the "hot shot" tweeters like a 3/4" Scan Speak, Focal, etc. Seems I remember some of them having real low Fs, and good power handling.
Guess I had it wrong about dispersion... I thought a 3/4" would have wider dispersion at higher fqs, and narrower dispersion at lower fqs, when compared to 1" domes.

GC

[dthomas]

Re: 8'' two-way any reason why not?

A 3/4" tweeter will have better dispersion than a 1" tweeter in the highest of frequencies. As the frequency goes down any dome tweeters dispersion WIDENS rather than narrows! If you wanted to match the narrow dispersion of a woofer at crossover, then technically you would need a tweeter the same diameter as the woofer!
A 3/4" tweeter is a poorer choice to match up with an 8" woofer simply because most 3/4" tweeters cannot be crossed over low enough.
Better off to use something even larger than 1" for instance the Morel MDT33 (33mm) 1.3"

Absolutely to everything AE said. Dispersion around the crossover because of the woofer won't be corrected by at smaller tweeter. Actually I am not aware of a 3/4" tweeter that will go low enough.

The North tweeter or the Seas 27TDFC or TBFC are probably the best choices out there right now. Cross at 1500Hz or so and all should be good.

[zach_t]

Re: 8'' two-way any reason why not?

I always thought an interesting project would be an 8"-10" driver with a "full-range" 2-3" cone driver. A lot of the 2-3" cone drivers have smaller "A" dimensions then the 1" tweeters. Just a thought.

[philiparcario]

Re: 8'' two-way any reason why not?

bandor makes a good 2 inch cone costly 250 a pair. this dm-4 should be a good one wait for zalph's measurments

http://techtalk.parts-express.com/showthread.php?t=207995

http://www.mark-daniel.com/Dir_En.asp?Proid=13http://techtalk.parts-express.com/showthread.php?t=207995

these are 250 a pair if they can handle 50 watts and cross at 800 to 1200hz these will work with most 8 inch woofers

[Guest]

Re: 8'' two-way any reason why not?

My favorite 8" two way:
http://www.geezas.net/kls9/main.html

Yes, yes, yes... AUDAX!!!
That's what I'm looking for now... Audax [and Vifa] 6.5" and 8" midwoofers!!!

GC

[gowa]

Re: 8'' two-way any reason why not?

I always thought an interesting project would be an 8"-10" driver with a "full-range" 2-3" cone driver. A lot of the 2-3" cone drivers have smaller "A" dimensions then the 1" tweeters. Just a thought.

Yes, I was thinking the same. The off axis seems to be lacking in this type of driver. These look interesting but not much info out there yet.

http://markaudio.com/alpair/6/round

[dthomas]

Re: 8'' two-way any reason why not?

Yes, I was thinking the same. The off axis seems to be lacking in this type of driver. These look interesting but not much info out there yet.

http://markaudio.com/alpair/6/round

Great idea but what always bothered me with this approach is that off axis response above 5KHz is really poor. The speakers never have that disappear effect in the room because all the harmonic stuff is very directional. Of course saying that I have never really tried to do it for this reason maybe it would work better than it appears.

I would think you are more likely to find an 8" woofer with good off axis repsonse at 1500 to 1800Hz than finding a 2" or 3" driver with good off axis above 5000Hz to 7000Hz.