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In the Forum: Audio Discussions
In the Thread: Constructing LF modules to the limits
Post Subject: Big vs. small.Posted by Romy the Cat on: 9/22/2011
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This is very interesting observation. I am in away envy that Petar went for a set of large woofers (4x23”!). This is the way to go! Unfortunately I did not experiment with it even I had the drivers and means to do it. My problem was with the fact that I need the woofers to be in time alight position and faced directly to the listening location. Pilling up the boxes of multiple 18” or 24” footer in the mid of my room would be very destructive to the way how my room “feels”. So I juts can afford to do it from decor perceive, so I never went there.  Still, the biggest reason however was not the decor consideration but that I feel very satisfied with the 25W drivers. I would like to add even more of 25W drivers, in fact I did plan to rebuild my woofer towers, putting 8-10 drivers per channel and increasing the depth of the boxes: I do not want to ad width of the baffle that I would like to keep at 12”. I never went anywhere with this project and I do not know if I will.

 haralanov wrote:
The second reason why I switch to considerably bigger woofer units is because they have much better tone (if properly made!). It is the same as reproducing a midrange with an optimized for midrange reproduction driver, instead of array of 10 tweeters. Well, using 10-20 tweeters to reproduce midrange will give you some midrange sound, but that sound is very far behind the sound of the dedicated midrange driver in context of tonal department.

With my very enthusiastic support of the haralanov’s bass move I would like to tone that the above quite is not truly accurate presentation of what is going on. First off all the collection of 10 tweeters are not the same of the collection of 10 woofers. Woofers do not suffer from HF lobbing and Woofers can form line-array that has a LOT of benefits at LF. It is not only about the better or worse individual woofer but about using the line-array benefits as well. Also, about the “tonal department” – it is depends how the woofers are used. In my case I cross then at 3rd and 4th order (different for L and R channels) at 20Hz. There is truly no “tonal department” in those frequencies and with such a steep orders.  I would say that it more colors the midbass channel then indicate own tone. So, I presume that in this context we can talk about tone of woofers. It of cause would be very different if the woofers are cross as 40Hz or at 80Hz… I do not insist that 25W drivers are great tonal drivers at any range and I do admit the there are many other woofers with paper suspension that are much more tonally capable.

 haralanov wrote:
There is another reason why I switch to bigger woofers, but this reason is indirect, because I can get the same effect by using a lot of 10 inchers. This is because sometimes I really love to listen at ultra loud levels, and I don’t want to have compression, distortion and dynamic restrictions in the low bass range when listening at 110-115dB. There will be around 2500 (there is no mistake in the number) liters of air behind EACH of the 4 woofers. May be in future I will add another pair of 23 inchers per side in order to have better dynamic reserve when listening at 120dB levels.
And not at the last place, I kicked the 25W woofers out of the system, because they tend to have just a slight taste of very soft rubber in the bass tone. This taste is very delicate, because the soft rubber is not directly in your mouth, but you feel the rubber as some kind of after taste after eating rubber in the previous day (just like eating garlic) but you can still feel it in your mouth/ear...

I am with you with the dynamic restrictions at 115dB. I do feel that 25W have it but are you sure that it is drivers but not your amplification? To drive them to 115dB at 20Hz would take an immense amount of power. What I observe is that with multiplication of 25W driver the effect of dynamic restrictions much softening and become very malleable, up to the point to be addictive in a way. I kind of like that very sort of “soft clipping”. It might not “impressive” but it is more forgiving and more naturally sounding to me.

About the “taste of very soft rubber in the bass tone”. At wish range? If you use then at 150Hz then they do sound like rubber garbage and nothing else. With drop of crossover point the rubber tone is gone and get converted to own very interesting infection of almost 2 harmonics. If you use them at let say 60Hz and sharp filter then I would not disagree that they have rubber sound. I do know rubber sound and it is not what it is as Sound of 25W does have differences that usually are eaten by the rubber suspension in the rubber sounding drivers. I would call it not “taste of very soft rubber in the bass tone” but rather the “driver own character” and I would like to note that I am not hate this character and differences of the bass notes are still well exposed though the 25W own character.

In the end I think the real test would be to make the an array with 8 or 10 ScanSpeak 25W drivers per side and to make two boxed with large woofer and compare at 20Hz. If one would ask me then I would bet on the large woofers. Still I do not think that line-array of the small drivers will be uncontestable. I do feel that line-array of the small drivers might be “enough”.

I know that it sounds like by saying all of it I justify my laziness not to going for large woofers. Still, I would like to remind you folks that among many of my diagnoses I am very prone to undertake some crazy audio projects. I have drivers, I have machines in the basements and I have a carpenter who only expects the command “fetch” as he will start to cut the wood in my basement -  when I get back from work the woofer boxed would be sitting there. I never went for it as I feel that the even my current small-array of 25W drivers is enough and does not give me a any frustrations for now.

Rgs, Romy the Cat

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