OK, I heard auditions of both Mark's and Papa Pass's speakers at BA 2013. I liked the bass on Nelson's system. Mark's was OK, too.
As usual, I'm lukewarm to downright down on Fostex/Lowther/(substitute yr expensive FR candidate here) single midbass drivers, as they don't do a good job (to my ears) on high volume, complex material, and high volume female voices (throw the 8" Hemp Acoustics driver on top of that pile, too, as evidenced by its performance at BA 2012)). I don't like female vocals that are a white-hot needle through my eardrums. Vibes at high volume can also elicit the hot needle. Some of this might have been due to other elements in the reproduction chain, but the speakers earn their share of opprobrium.
At any rate, I want to work on my own solution/satisfaction to the mid/HF part of the reproduction chain, but I was intrigued by the simplicity of the LF part of Nelson's demo speakers. It hasn't been nailed down exactly what was doing the low end duty - Eminence, yes, 15", most likely, facing the floor - most definitely. The mid price or high price drivers? Slot loaded or just OB facing the floor? I'm inclined to an OB line array of many speakers for mid/HF duty, and a down-firing big speaker would be just the ticket to give me the bass I want and keep the whole assemblage from tipping over. A couple of lead bricks wouldn't hurt, either.
As usual, I'm lukewarm to downright down on Fostex/Lowther/(substitute yr expensive FR candidate here) single midbass drivers, as they don't do a good job (to my ears) on high volume, complex material, and high volume female voices (throw the 8" Hemp Acoustics driver on top of that pile, too, as evidenced by its performance at BA 2012)). I don't like female vocals that are a white-hot needle through my eardrums. Vibes at high volume can also elicit the hot needle. Some of this might have been due to other elements in the reproduction chain, but the speakers earn their share of opprobrium.
At any rate, I want to work on my own solution/satisfaction to the mid/HF part of the reproduction chain, but I was intrigued by the simplicity of the LF part of Nelson's demo speakers. It hasn't been nailed down exactly what was doing the low end duty - Eminence, yes, 15", most likely, facing the floor - most definitely. The mid price or high price drivers? Slot loaded or just OB facing the floor? I'm inclined to an OB line array of many speakers for mid/HF duty, and a down-firing big speaker would be just the ticket to give me the bass I want and keep the whole assemblage from tipping over. A couple of lead bricks wouldn't hurt, either.
How about keeping the woofer tall enough to eliminate the floor bounce ?
Problems associated with arrays are well known, as the tricks to minimize them -controlled directivity and progressive crossover technique.
OB is good as the membrane movement is not influenced by changes of pressure of a box, but is bad as the back emission is the 100 % error - the negation- of the frontal one.
Problems associated with arrays are well known, as the tricks to minimize them -controlled directivity and progressive crossover technique.
OB is good as the membrane movement is not influenced by changes of pressure of a box, but is bad as the back emission is the 100 % error - the negation- of the frontal one.
No, I don't think it's well known.
One of the major deficiencies of normal boxed speakers is that the cone is pretty transparent to bass frequencies, as also the box.
By eliminating the box you just eliminate the internal pressure which modulates constantly the movement.
So with OB you hear mostly the frontal emission, but there's also the backwave which is 100% negation ( antiphase) of the frontal one.
The brain discerns the good from the bad, but it still exists.
So for OB you pick a large woofer to overcome with its possance the effect
of acoustic short circuit; big cone and long excursion.
tube amps or SS with low damping factor may become useful for this task
One of the major deficiencies of normal boxed speakers is that the cone is pretty transparent to bass frequencies, as also the box.
By eliminating the box you just eliminate the internal pressure which modulates constantly the movement.
So with OB you hear mostly the frontal emission, but there's also the backwave which is 100% negation ( antiphase) of the frontal one.
The brain discerns the good from the bad, but it still exists.
So for OB you pick a large woofer to overcome with its possance the effect
of acoustic short circuit; big cone and long excursion.
tube amps or SS with low damping factor may become useful for this task
well , there is reality and .......... reality
look at this : Tannoy OB fun ...... brute force approach - diyAudio.rs
according to MJK MathCad sims , there is no way that that combo is having any bass ; but - situated as on last pic on linked blog , speakers are not on OB anymore , but more on U frame
even if I (still ) didn't made any measurement ( in a meantime lower Tanns replaced with Beyma SM-115N ) there is more than enough bass in our smallish living room , both in quantity and quality
one of great things with OB is that room modulation is surprisingly lower than with other types of enclosure
look at this : Tannoy OB fun ...... brute force approach - diyAudio.rs
according to MJK MathCad sims , there is no way that that combo is having any bass ; but - situated as on last pic on linked blog , speakers are not on OB anymore , but more on U frame
even if I (still ) didn't made any measurement ( in a meantime lower Tanns replaced with Beyma SM-115N ) there is more than enough bass in our smallish living room , both in quantity and quality
one of great things with OB is that room modulation is surprisingly lower than with other types of enclosure
Go Wrenchone! I like what your say'in. I beleive a line array of smaller OB drivers can easily cover from 150Hz up to 2-3k. And, in doing so, aleviate the lower 6db/oct rolloff, to something more like 3db/oct, while spreading out the "6db peak", and allowing operation into the nulls, without the nulls, depending on CTC of the line drivers. Looking forward to more of these thoughts
Thanks, for the update, Nelson. I have enough info to start with, though 200 bucks/drivers is not precisely what I'd call cheap.
There are enough threads on OB that I didn't want to bloat this thread with yet another extended wrangle. My purpose for starting this thread is fufilled. Let's have it remain short so that other people can easily find the answers I was seeking.
There are enough threads on OB that I didn't want to bloat this thread with yet another extended wrangle. My purpose for starting this thread is fufilled. Let's have it remain short so that other people can easily find the answers I was seeking.
The woofer was the Eminence Definimax 15", which is not very expensive.
The crossover and equalization is detailed in the SLOB article.
As it is mounted a few inches above the floor, there is no floor bounce to
speak of.
I re-read the SLOB article. Would it be possible to post the plans for the BAF speaker?
This is already out there in the SLOB article. Anybody here know how to hook up an op amp?
I was more interested in the baffle size and woofer mounting construction. The XO has been well explained.
Would you post the construction details?
I, me, my, myself was less than interested with all the electrical filter stuff, but intensely, vitally interested in the actual physical package of 15" speaker plus "enclosure". I can work out the details for the active filter on my own (I have a Beringer mike that needs some gainful employment). This exercise might end up as a subwoofer package that ends up being coupled to various mid/high end combinations (one of which might end up at BA 2014)..
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