|
|
Post by chrisbee on Apr 6, 2012 9:15:30 GMT -7
Thank you, Thomas.
I have been doing some swift homework around the forums on H-frames. I quite like your horizontal arrangement of driver pairs or preferably four singles. Pairs of 15" drivers would be vertically challenged under my sloping ceiling. They'd be at least 36" high if any meat was left around them on the baffles.
Sunburn? Just be grateful I didn't go with my natural green. ;D
|
|
|
|
Post by FOH on Apr 6, 2012 10:44:06 GMT -7
Nice goatee, I recently took mine off, ....... I do however, see the problem. You're missing your pinna. The spectral shaping and lack of direction cues must psycho-acoustically drive you nuts*.
I'm not well versed in OB bass what-so-ever. I do have a much better understanding of what's going on,...so thank you both for that.
*A Pirate walks in a bar, bartender says "why you got a steering wheel sticking up out of your pants"?
.......The Pirate replies "aaarrrrrrr, it's drivin' me nuts" ;D ;D ....
Good luck Chrisbee
|
|
|
|
Post by chrisbee on Apr 6, 2012 13:56:28 GMT -7
Forgive me if I don't continue with this enjoyable discussion. We have just heard of the loss of a family member. There is absolutely no need for messages of sympathy. Just thought I'd explain why I'm going to be busy elsewhere for a while. Thanks for all your responses.  Back soon.  Chris |
|
|
|
Post by chrisbee on Apr 8, 2012 10:32:45 GMT -7
Bad penny? What bad penny?  Thomas, From a mock-up I have discovered that I have just enough room for two H-frame dipoles. These would be two drivers high and of minimum size to house the drivers. As they would be tucked under the sloping ceiling all discussion about having air around them becomes superfluous. Though I can always fix them to the ceiling to stop them rocking if it proves necessary. This is hardly the place to discuss H-frames so I shall continue my research elsewhere. I already like how the Orions sound on YT. Many thanks for the suggestion. Chris |
|
|
|
Post by ThomasW on Apr 8, 2012 10:47:28 GMT -7
Hi,
Good to know they'll fit in the space.
There is a TON of info on the web regarding OB/dipole designs. Obviously Linkwitz's site is where to start.
BTW is it out of the question to make a hinged door that lowers to cover the stairwell?
|
|
|
|
Post by chrisbee on Apr 8, 2012 11:26:40 GMT -7
Hi, Good to know they'll fit in the space. There is a TON of info on the web regarding OB/dipole designs. Obviously Linkwitz's site is where to start. BTW is it out of the question to make a hinged door that lowers to cover the stairwell? It's a tight squeeze but two dipoles will just fit in the gaps behind and between the TV and speakers. I'm still unsure how deep I can make them (front to back) They will hit the ceiling or push the speakers into the stairwell void if they are made too deep. I'm not looking for infrasonics from them. Because the 4 x 15" iB will fill the bottom end as usual. I have been trawling for info on dipoles for the last couple of days. Read much of what is out there. A hinged trapdoor won't work on the open stairwell unless I remove the banisters. This has always been the impossible hurdle to overcome. The stairs are about 60 degrees so it just isn't safe without something firm to hang onto. Each tread hits the back of one's calves on the descent. We have become incredibly nimble on them but safety comes first. Thanks |
|
|
|
Post by ThomasW on Apr 8, 2012 12:10:34 GMT -7
A hinged trapdoor won't work on the open stairwell unless I remove the banisters. This has always been the impossible hurdle to overcome. I wasn't advocating removing the banisters. I assume the banisters form a square 'U'? If so here are more free ideas.... ;D 1) A sliding hatch type door 2) A split down the middle door (similar to cellar) where 1/2 rests on each long banister when open  |
|
|
|
Post by chrisbee on Apr 8, 2012 13:55:14 GMT -7
If the banister was horizontal I could quite like your double cellar doors. Sadly the handrail in question follows the line of the stairs and sticks out into the stairwell by over 6". Only half of the stairwell opening could be covered without the hatch colliding with the banister rail and newel post. As you may imagine, I have stared at this intractable problem for over 15 years. Without ever coming up with a practical solution. I have considered a door at the bottom of the stairs and filling in the open side to the room. There is simply no room for a door to swing. It might be worse acoustically if I could put one down there. I'm not fond of sliding doors. Thanks for the excellent ideas though. |
|
|
|
Post by chrisbee on Apr 10, 2012 9:35:39 GMT -7
I threw together one 2 x 15 H-frame OB using only 100mm frames front and back. The idea being to push the expected baffle resonance up out of harm's way. I wasn't looking for deep bass anyway. I put the OB on the right of the TV with a clear view inside the right speaker. I haven't cleared any storage from behind the OB yet. It was driven by my old SVS Bash amp for REW tests. Set at maximum, 120Hz crossover. Measured at the listening position. It sounds very different from the IB but not offensive. I will have to connect it to the system tomorrow to see if it fills the ~150Hz trough. Then I will have BFD EQ and a free choice of crossover point. Attachments:
|
|
|
|
Post by chrisbee on Apr 10, 2012 9:43:51 GMT -7
Crossover bypassed on SVS amp. 2 x 15" OB vertical 4"/ 100mm frames measured at listening position. Attachments:
|
|
|
|
Post by chrisbee on Apr 11, 2012 23:53:52 GMT -7
The OB has been returned to the wood shed.
The response was just too strange to do anything about my sub-200Hz cancellation trough.
Though very powerful, the OB's SQ wasn't as good as the IB. It had similar properties to a bandpass sub. Though with a very narrow power band.
I was pleasantly surprised how little it vibrated even at 100+dB levels on Bass Outlaws. I'm putting this down to limited infrasonic reach compared to the IB.
The OB was a great idea because it was all inside the warmed room and not obstructively large. Perhaps it would have been better as a simple open baffle to reduce that 30-50Hz hump?
But this is all digressing from the core topic of IBs.
Had I followed foh's expert advice... I really ought to have fitted my IB with a steering wheel by now. ;D
|
|
|
|
Post by FOH on Apr 12, 2012 10:22:25 GMT -7
........ Had I followed foh's expert advice... I really ought to have fitted my IB with a steering wheel by now. ;D aaaaarrrrrr,.....  |
|
|
|
Post by FOH on Apr 12, 2012 10:24:51 GMT -7
That's all I got in this regard,..OB stuff I've never ventured into...I defer to yourself, and our leader ......  |
|
|
|
Post by ThomasW on Apr 12, 2012 11:49:46 GMT -7
OB/dipole is to the woofer and midrange passbands as IB is to the sub passband, the best sound possible because the 'box' is virtually eliminated.
OB/dipole designs also help eliminate some of the detrimental effects caused by forcing a speaker operate inside a 'room'
The deep nulls at the sides of the baffles combined with the out of phase rearwave bounding off the backwall makes the sound overall more 'open' and 'airy'.
|
|
|
|
Post by chrisbee on Apr 12, 2012 12:06:20 GMT -7
OB/dipole is to the woofer and midrange passbands as IB is to the sub passband, the best sound possible because the 'box' is virtually eliminated. OB/dipole designs also help eliminate some of the detrimental effects caused by forcing a speaker operate inside a 'room' The deep nulls at the sides of the baffles combined with the out of phase rearwave bounding off the backwall makes the sound overall more 'open' and 'airy'. Thank you, Thomas, I'm not going to argue. OBs were a great idea in theory. I think my problem was that the OB was under the overhanging, sloping ceiling. It was also enclosed by the TV and main speaker. This all increased the effective baffle size to boost the lower bass out of all proportion. The hump at 30-50Hz easily made me feel nauseous. While the upper bass was just too ragged to be worth persevering with. I made the frames deliberately narrow to try and limit the lower bass. It didn't work. These plastic coned IB drivers may not be ideal anyway. Smaller, plain baffles made them sound very "jangly". A couple of 12" or even 10" might have been a better idea. In a normal room I imagine much could be done with OBs. Some of the YT videos sound very decent indeed. Despite the inevitable, technical limitations of the recording and playback process. |
|
|
|
Post by chrisbee on Apr 12, 2012 12:11:38 GMT -7
That's all I got in this regard,..OB stuff I've never ventured into...I defer to yourself, and our leader ...... You give me far too much credit and are far too modest about your own skills and experience. |
|
