Hi Simon,
The moment you put box like sides on a baffle you set up a reflective pressure differential which might well sound like an upper bass peak.
'H' sides are better than 'U' sides because the front-rear reflected pressures are better balanced with respect to the cone.
Your capacitors not warm - you are not shaking the place then !
(I do!)
Frequency doubling - a driver characteristic - esp smaller ones - could contribute to pressure differential induced re-radiation not adequately controlled by drive/Qes.
Cheers ...... Graham.
The moment you put box like sides on a baffle you set up a reflective pressure differential which might well sound like an upper bass peak.
'H' sides are better than 'U' sides because the front-rear reflected pressures are better balanced with respect to the cone.
Your capacitors not warm - you are not shaking the place then !
(I do!)
Frequency doubling - a driver characteristic - esp smaller ones - could contribute to pressure differential induced re-radiation not adequately controlled by drive/Qes.
Cheers ...... Graham.
Thanks for the interesting comments Graham.
Intuitively, I suspect the peaking is mostly because I've raised the bass output by using more drivers but am losing lower bass due to the dipole roll-off.
I will experiment and measure.
Does anyone ever line the inside of their wings with foam to reduce any possible standing waves? They're supposed to be out of those drivers' range but I think a little is creeping through (obvious when behind the speaker).
Simon
Intuitively, I suspect the peaking is mostly because I've raised the bass output by using more drivers but am losing lower bass due to the dipole roll-off.
I will experiment and measure.
Does anyone ever line the inside of their wings with foam to reduce any possible standing waves? They're supposed to be out of those drivers' range but I think a little is creeping through (obvious when behind the speaker).
Simon
Another thought - the rear of baffle sides could be intensifying corner reflection of high bass frequencies.
Try giving the outside wall of the back a panel to reflect rear waves into the centre of the front wall. Might not work but worth a try.
Cheers ........... Graham.
Try giving the outside wall of the back a panel to reflect rear waves into the centre of the front wall. Might not work but worth a try.
Cheers ........... Graham.
I can try this.... The left speaker (corner!!) is much more droning in the bass than the right. I've had each running individually and whilst they work fine near walls, they'd sing even better in more space.
No choice for me right now though.
Simon
No choice for me right now though.
Simon
SimontY said:
For side wings only, in other words still open at the top, you will not get any standing waves in the cavity formed by the front baffle and the side wings. You will hear a change due to a different sound radiation pattern but not due to any standing wave resonances.
Thank you Martin.
I have ordered some coils to play around with. I will roll off the bottom two woofers differently from the top two.
Simon
I have ordered some coils to play around with. I will roll off the bottom two woofers differently from the top two.
Simon
richie00boy said:
You think that one's causing issues?
I think I'm going to leave it till I get some coils. There's definitely missing lower midrange and too much upper bass, which they can cure by tailoring what each of the 4 woofers does.
In the meantime I'm trying, in vain, to find my cheapo microphone so I can get some idea of what's really going on. I've already turned over several boxes of junk 😀
Simon
Nuuk said:It won't turn up till you stop looking for it Simon!😉
Don't I know it?!
I need to look into a more suitable measurement microphone anyway. A friend bought a Behringer ECM8000 for me to use on his behalf, but it was DOA and they never actually replaced it! I then gave up
SimontY said:
What you´ve got here now is a U frame for the woofers. Since the frame is rather shallow, the quarter wavelength resonance should be quite flat and up in frequency - perhaps outside the woofer passband.
I would not cut those holes.
What I don´t like is the midrange near to the top brace. Maybe you want to test some absorbing material on top of that brace.
Rudolf
I considered this Rudolf. Tonight I will add some damping material there and report back.
Simon
Simon
It may not make a hell of a difference, because it is in the back. But since it is easy to try out ...SimontY said:
Indeed. By the way, what a shame I can't read German because your website looks very interesting!
Simon
Simon
I was just thinking of one of the comments about standing waves being possible between the top and bottom braces, but if you are filtering the woofers to cut a good way below the frequency where standing waves would happen to a significant extent maybe it's not necessary.
richie00boy said:
At present the woofers come in, first order, at 180hz. I intend to raise this for the top two, and lower it for the bottom two. The idea is to improve the lower midrange response and mate with the little Audax mid better, and to reduce the upper bass peak I can hear.
Simon
weidok said:
I have the same fostex 167E on open baffle, I found the sound a little thin, overall sounds OK however if you have a better quality midrange driver the midrange would sound much fuller(I like fuller sound). On top of that it cannot handle power. For the price it is selling it is well worth it for the sound.
BTW I use an old alnico mid/woofer it sounds better than Fostex 167E
Cool designs guys, I heard a speaker with some old Goodmans 12" full range drivers and was impressed. I can imagine the Fostex being hard to get just right.
Weidok,
How did you tackle the dipole peak? Or is it left as-is?
Simon
Weidok,
How did you tackle the dipole peak? Or is it left as-is?
Simon
I decided to stop merely guessing at the frequency response so I ordered a pre-amp kit and electret capsule from Mad About Sound (Vikash's web-site).
(I can't remember if I mentioned that before or not.)
Simon
(I can't remember if I mentioned that before or not.)
Simon
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