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In Reply to: Here Are The Specs Re: Do you think they would run up to 250 hertz well? posted by Dr Deville on February 5, 2007 at 14:32:38:
The dip at 750hz looks nasty,but its probably inaudible,the room will do that sort of thing too.Most people XO their high mass sub only woofers nearer 100hz so this is abit more difficult.Perhaps more prosound style woofer,with EQ will work.
Have you looked at Hawthorne Augies?I think they go ~500hz.Beaming wont be a problem,It isnt going to be beaming at something like 45* angle.
A slight amount of beaming eg 90* at 1.5 khz will help reduce room interference anyway.
Mike.e
There are three constants in life: death, taxes, and the inevitability of a (speaker)wire thread being closed -SY
Follow Ups:
Hey Mike,Thanks for the helpful thoughts! Good to hear that beaming might not be an issue.
"Most people XO their high mass sub only woofers nearer 100hz so this is abit more difficult.Perhaps more prosound style woofer,with EQ will work."
Is there a particular reason why a woofer like the Dayton or the Hawthorne wouldn't sound good above 100Hz, even if the frequency response looks good? (I'm hoping the typical 100Hz crossover has more to do with the higher frequency drivers typically used in boxed speakers, rather than an inherent limitation of the Dayton)
Yes, I am considering the Hawthorne Augie, though its website presents limited specs, and no frequency response graph. Plugging it into Thorsten Loesch's spreadsheet (and guessing at the missing parameters) gives higher efficiency than the Dayton, but much more rolloff below 40Hz.
Since I'm going to use a random solid state amp for bass, I don't particularly care about woofer efficiency, but I do care about low frequency extension.
That, combined with the fact that the Dayton shows a response graph, is cheaper ($110/ea for four), and has a Q of 0.69 versus 0.92 for the Augie, has me leaning towards the Dayton.
I'm thinking dual Daytons per side--sort of a knock-off of quarter-wave.com's Project 7:
http://www.quarter-wave.com/Project07/Project07.html
He crossed-over at 100Hz, but I'd like to experiment with higher frequencies, with 100Hz as a fallback.
All comments, insights, and suggestions appreciated.
Thanks!
George
Is there a particular reason why a woofer like the Dayton or the Hawthorne wouldn't sound good above 100Hz, even if the frequency response looks good? (I'm hoping the typical 100Hz crossover has more to do with the higher frequency drivers typically used in boxed speakers, rather than an inherent limitation of the Dayton)The problem is in the measurements themselves. Conditions such as boundarys,indoors or out,smoothing applied etc.
You probably already know about people measuring nice responses and not hearing a nice musical result.Interpreting graphs brings in psychoacoustics,low Q vs high Q resonances for example.
The alpha15 looks good according to that site.Xmax is a little low,but 4 total should be enough for sane volumes.
Can you post more detail about what the entire system eg why 250hz XO.
Regards
Mike.e
There are three constants in life: death, taxes, and the inevitability of a (speaker)wire thread being closed -SY
Mike Wrote:"Can you post more detail about what the entire system eg why 250hz XO."
Thanks Mike--Oh boy can I (grin).
The starting point is I'm building a 300B SET (my first SET experience), and want to hear that fabled SET goodness hooked to a driver with no passive elements.
I decided to start with a Fostex fullrange, as a good bang-for-the-buck starting place.
Reading up, I found a lot of issues in coaching simultaneous bass, volume and clarity from a FR Fostex, so I decided to bi-amp to take the burden off the Fostex.
I was originally going to go with something like Bottlehead/Paul Joppa's S.E.X.y speaker--FR Fostex in small sealed box, dual inexpensive bass reflex subwoofers. But my love for dipole systems (Magnepan, Dahlquist DQ10) pushed me towards open baffle, and my desire for well integrated bass led me towards open baffle bass.
Which leaves me at my current bogey: digital crossover/equalizer sending highs to a 300B SET wired straight to an open baffle Fostex fullrange, and lows to a random sand amp wired straight to open baffle woofers, probably two per channel.
Bottom line is, the 250Hz crossover point is far from set in stone, but I would like drivers, particularly bass ones, that would allow me to experiment with XO points between 100Hz and 500Hz.
If a relatively low crossover point, say in the 250 to 350Hz range, sounds good, it will unburden the SET/Fostex combo, allowing higher volumes. Vocals are my main priority, so if moving the transition up towards 300Hz hurts the vocals, I'd set it lower.
My current choices are the Fostex FX120 and the Dayton 15" OB Woofer.
My thinking is the high end of the FX120 looks flat and extended, it has no whizzer to resonate, and biamping will effectively raise its sensitivity 6dB to 95dB, which I'm hoping will be fine with the 8W 300B SET.
The Dayton IB Woofer (part number 295-455, 15", Qts 0.65, Fs 20.8Hz) has smooth response up to 700Hz and very extended bass. Using Thorsten Loesch's Xlbaffle spreadsheet and plugging in a 40" baffle, I get +-1.5dB down to 30Hz, -6dB at 20Hz, before equalization.
So I hoping those two would be good fodder for experimentation--I could mess around with the digital crossover until I get slopes, frequencies and equalizations that I like. Then I could hardwire a line-level crossover with analog components if I wanted.
Of course that's all theoretical, and I've don't have the components to audition, so I'm just winging it as best I can.
So there are the specifics and my rational/preferences. All comments, insights, suggestions greatly appreciated. Thanks for the help you've already given me.
Best,
George
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