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A Discussion on Design Philosophy - OB vs Multiway vs NOB
A Discussion on Design Philosophy - OB vs Multiway vs NOB
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Old 9th July 2014, 05:23 AM   #1
miragem3i is offline miragem3i  China
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Join Date: Jul 2010
Location: Western China
Default A Discussion on Design Philosophy - OB vs Multiway vs NOB

I have two OB projects, one on 3 inch on a wooden board and the other a 2-way with a pass filter cap on cardboard.

I finialised my 2-way TV box upgrade yesterday and it sounds good.
But it does not have the imaging of a cheap 3 inch wide range driver stuck on a board.

What I realised is that while, yes, I hear the lower end (that so many here insist I must have) from the enclosure and the 3 inch, that trying to get all things from any given design may be a mistake.

Open Baffles have natural rolloff below 250 to 200hz, Attempting to fix that, make the system do what it does not naturally wish to do, requires big baffles, BSC, more drivers, XO, and the like.

Box enclosures, ported, TL, sealed, whatever, all end up with the same issues. Integration of the drivers and crossover to present a cohesive soundstage and resonance of the enclosure. Wilson Audio goes to extremes with cast resin cabinets lined with lead to dampen resonance.

I can clearly hear the congestion, constraint, contained, caged, boxy sound of the 2-ways even though they have better slam, impact and bass FR than the 3 inch OB or the 2-way OB. The bottom end and lower mid sounds more like a band playing in the next room, but when I sit down at the sweet spot it's clear that the box is hampering the midrange, vocals and sound stage.

I can hear, clearly, phase shift and XO artifacts in the sound stage presentation when an XO is used compared to one driver connected to an amp on an OB. It's very noticeable to me especially regarding the soundstage. Midrange and vocals are also altered.

A NOBaffle has even a slightly clearer and cleaner sound as the minimal cardboard and wood resonances are absent, with the loss of a bit more slam, impact and bass. But that vocal and crucial midrange (300-3000) realism gets me every time.

For me, and I am by this point well aware of the many biases that so many here have regarding my projects and what I want to do and what I like, it seems more sensible to have several systems with their own strengths.

1) A mutli-way system that sounds good with casual listening, not critical sitting in a sweet spot. This would be my current 2-way on their stands, with a sub or bass enclosure added. Yet another XO would be added, active one to split and control the signals, but I would always be unhappy with the confined nature of the sound.

It does sound good as I walk about the house.

2) An OB one driver wide range setup on a board. No eq, BSC or any other processing. Wires from amp to speaker terms and that is it.

This would sound excellent for seated, critical listening of most kinds of music. It would excel at sound stage and vocals and midrange. I could do without the bass for rock, jazz, deepest acoustic notes of symphonic instruments, etc.

FR for this OB would be 100-9000hz or so depending on the driver used. I have experimented and I ""need"" 9000hz as the barest of minimums to hear cymbals and such with air, above that to 13,000 is noticeable but not necessary and above 13,500 is inaudible to me.

3) A NOBaffle one driver wide range , basically speaker on a stick, on a pole, hanging from a frame on wire, string or rubber elastic cord. Not as fancy as those Polish 3-ways on welded cast iron frames, but the same idea of no box no baffle.

FR for this NOB would be 250-9000hz and up.

This would be excellent for acoustic music and vocals, not rock, chamber pieces, nothing with a great deal of bass or cymbal content. The all important midrange would be the strong point here, cancellation as front wave meets back would not matter in this context.

For me, I see using several systems for their strong points as a great way to ''have it all''.

I find that 3 inch drivers are the best at wide range sound with minimal ringing and upper treble artifacts. As the drivers get larger the sound volume increases, of course, but the drivers all begin to have issues creating a full range of sound as the surface of the cone just is not meant to do this in real time. 4 inch drivers are good and can do this as well as most 3 inch, but once I get to 5 inch drivers the issues arise and increase as cone diameter increases.

Phy-HP and Lowther are great examples as they become shouty and have issues as they try to do it all at 6.5 and 8 inches in a wide range single driver context.

As far as realistic volume levels that is right out. Neighbours are 2 metres away on all sides and I do not enjoy loud music much above 100dB these days. I turn it up for a few minutes but tire, my ears tire, quickly and it's bothering all the neighbours. I estimate a dozen houses within earshot.

Perhaps I am leaning towards the 86dB perfect level that some advocate. Perhaps not. I do not have an SPL about to check.

The main constraints are that I am extremely sensitive to sound stage and mid range, and I have no wood working and cabinetry skills at all and thus cannot fabricate enclosures.

My sole question is:
Do others have multiple systems on hand that have various strengths for different musical types?

Last edited by miragem3i; 9th July 2014 at 05:27 AM.
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Old 9th July 2014, 01:30 PM   #2
zman01 is offline zman01  Bangladesh
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Join Date: Feb 2011
Location: Dhaka
A Discussion on Design Philosophy - OB vs Multiway vs NOB
I have no experience with OBs; however you can take a look at this thread for some discussion on OB with wide-band / FR drivers:

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Old 10th July 2014, 04:02 AM   #3
miragem3i is offline miragem3i  China
diyAudio Member
Join Date: Jul 2010
Location: Western China
I have thought of just such a compromise for one system but ultimately the simple signal chain benefits of improved sound stage prevail over all other considerations.

TimBoz in that thread stated something close to my viewpoint. An OB for classical jazz acoustic and another system for contemporary pop and rock.

Last edited by miragem3i; 10th July 2014 at 04:25 AM.
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