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Old 29th September 2012, 04:08 AM   #21
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Quote:
Originally Posted by Silent Screamer View Post
Just trying to get some sort of an idea how far a larger OB bass driver should move in regular music use.

I keep reading that you need drivers with a big excursion and mine is capable of some fairly big numbers (several inches), but the cone would be lucky to be moving .5mm-1mm.

Just trying to work out what is normal for OB.
I think you answered your own question.
If it only moves a little bit then it only moves a little a bit.

Stop listening to the rubbish people tell you and have faith in yourself

My dual 15s also barely move. My fingers and mach 3 calibrated eyeball tell me roughly +/- 0.5mm, (and obviously less than that as you go up in frequency)
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Old 29th September 2012, 04:16 AM   #22
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Quote:
Originally Posted by Silent Screamer View Post
Just trying to get some sort of an idea how far a larger OB bass driver should move in regular music use.

The reason I ask is that I have my new 18" Tc Sounds Pro 5100 (only the one) just sitting propped up on the floor.

It seems to put out a reasonable amount of sound (although currently crossed over a little high ~300Hz) but I notice the cone barely moves.

I keep reading that you need drivers with a big excursion and mine is capable of some fairly big numbers (several inches), but the cone would be lucky to be moving .5mm-1mm.

Just trying to work out what is normal for OB.
It doesn't move a lot until you equalize for dipole roll off (doubling excursion for each octave) and run low frequencies through it.
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Old 29th September 2012, 04:29 AM   #23
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Originally Posted by Drew Eckhardt View Post
It doesn't move a lot until you equalize for dipole roll off (doubling excursion for each octave) and run low frequencies through it.
Even then, it is not going to move much listening to regular music
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Old 29th September 2012, 04:31 AM   #24
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Quote:
Originally Posted by Drew Eckhardt View Post
It doesn't move a lot until you equalize for dipole roll off (doubling excursion for each octave) and run low frequencies through it.
Guess this really sums up what I have found. Theory is one thing but hands on experience is quite another. In hindsight for OB bass woofers I think I would probably consider Xmax less next time, because as you say unless you are really pumping up the EQ to compensate for dipole roll off it really doesn't even come into the equation.

Currently I am listen to Brian Cadd and it sounds fine, a tiny bit short on mid bass / vocals but not much, and I dont have the woofer in the best configuration to maximise the larger driver, so there is more free stuff to come (and a second channel).

And what it is missing is probably in the 100-1000hz range where the mid woofer I dont currently have would fill in.
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Old 29th September 2012, 04:36 AM   #25
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1mm xmax is plenty for me on my dual 15s on open baffle (Eqd flat to 40Hz)
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Old 29th September 2012, 04:54 AM   #26
boris81 is offline boris81  United States
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I'd say most thumping bass in electronic music is 50-100Hz and generally large excursions happen below that. Equalizing for OB roll-off adds about 10-20dB which is a lot!
I can rarely hear (or feel) the sound when I see the woofers move a significant amount. If there is a visible large excursion it's most likely caused by subsonic content.

The ending of Tchaikovsky's 1812 Overture bottoms out my woofers pretty bad. Give it a try!
Tchaikovsky's 1812 Overture, Op. 49 - TELARC Edition - WARNING! Digitally Recorded LIVE Cannons! - YouTube
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Old 29th September 2012, 05:05 AM   #27
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Thanks everyone for their input, I guess the "average" (of those that offered measurements) is "very little" (~+-1mm) for typical music at listenable levels. Which does make me feel better that what I have is not uncommon.

Quote:
Originally Posted by Silent Screamer View Post
Yep the booklet shows two different configurations serial and parrallel have them hooked up 2 + 2 for a 4ohm output, serial produces 1ohm (which I think my amp might just protest slightly)
Slight correction, back to front, I have them hooked up in series not parallel as stated earlier. I have my 8ohm mids in parallel.
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Old 29th September 2012, 05:15 AM   #28
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Regarding your setup, I would use the TC pro below 40Hz and get 2 pairs of GPA 416 woofers between 40Hz and 500Hz.
You will save yourself some money and end up with something that will match better with your mids.
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Old 29th September 2012, 05:32 AM   #29
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It is worthwhile breaking your woofer in.
I have found big woofers take quite a bit of exercise to break in, and for TS parameters settle down.
4Vpk at 20Hz will get those woofers moving. Or if you can sweep between 20Hz and 40Hz contiuously at 4Vpk
Let it run over night

Last edited by Murphys Law; 29th September 2012 at 05:36 AM.
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Old 29th September 2012, 05:38 AM   #30
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Cost has never been a strong consideration in this build...

I quite like the sound of the Pro 5100 in the current frequency range, if they had sounded boomy or unatural, I would have religated them to sub duty, and put something else in their place, but I quite like the very subtle blend they provide.

You would think that crossing over from a pair of 120mm mids to an 470mm woofer would sound like absolute crap, but nothing could be further from the truth.

The mids needs some vocal propping up, they measure down to a few hundred hz but there is no real body to them. They have great definition and work higher up but I'm not covinced they have the oomph to pull off really low frequencies.

I have them crossed over to to RAALs at 4000hz at the moment. What I need is a strong vocal mid woofer around 8"-10" so I can cross the mids over higher.

The TC Sounds 18" does a really nice job in the intended 50-200hz range I bought it for, it was never designed to be an all out wall shaker. I have planned sub woofers for that duty.

I know you keen on those GPA 416 and I would like to give them a listen sometime but not for this build.

Next step is to find a suitable mid woofer to replace the 10" hard paper Vifa drivers I had standing in for a temporary bass.

Before I side tracked myself going down the OB route I was actually looking at some folded horn for bass. Might even do that rather than a BR sub cabinet.
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