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Multi-Way Conventional loudspeakers with crossovers

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Old 25th February 2007, 11:10 PM   #401
ScottG is offline ScottG  United States
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Quote:
Originally posted by ShinOBIWAN


I know from experience that my room has a bump between 30 and 40hz so this will likely be better. That's my reason for not porting - an 8" will almost certainly be tuned in that 30-40hz range. Most ported designs don't work well in my room, the B&C sub did because it was tuned to 19hz and didn't have to sit where the loudspeakers normally do.

That is just an spl-thing. If the thing is purposely tuned for a lower spl in this passband then it is equivalent (..or if filtered). Additionally the substantial physical separation will almost certainly alter this.

I like the mid with mid reinforcement - I've used it before to good effect. I've also done something similar with tweeters to reach a lower cut-off freq. while maintaining fairly low non-linear distortion.

Even an 8" max thing is OK (..like you an many others, I also like speakers that are slim). What I think will have to change is volume (particularly if sealed) which means either additional cabinets in the future or, like a porn star going for the money shot, "go deep".
Perhaps even including a compound configuration.
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Old 25th February 2007, 11:21 PM   #402
Salas is online now Salas  Greece
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The sub driven alone, here. The PHL receives a 6db roll off under 200Hz and its in sealed box too.

Underside, with mean level line, the total response with PHL in. One division = 1dB.

I knew that from the start, because that room gain is my room gain. And I don't predict tarantism I just say things are brighter than initially looking and a dipole monster sub with dsp is only one evening woodwork for our thread host.
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Old 25th February 2007, 11:30 PM   #403
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Originally posted by tinitus Nice pictures, Shin - something that nice will sound good, I am sure
Ah you see! You don't have to worry about whether they'll sound good, just enjoy the pretties.

If they don't sound good I'll come back, let you know and see if it can't be fixed.

Quote:
Some time ago, we laughed at a designer who proudly claimed that he could hear 20hz from a small speaker, when sitting under a table....ups, sorry Salas I was not thinking of you
I've heard 20hz on headphones. Actually it might have been a mix of 40, 60 and 80hz. I just can't tell

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Funny, sometimes when sitting at the computer, I hear very deep well defined tones coming from the other end of room opposite the speakers, but sitting in listening position, nothing of that
Move you listening position to the where the computer is
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Old 25th February 2007, 11:47 PM   #404
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Quote:
Originally posted by tinitus
Shin, I think your measurement only show a ressonance below 20hz, nothing else and certainly not the woofer playing music
Not my measurement but taken from the Swedish sub tests done by Ilkka.

Its an FR sweep and shows what it shows. Model the XLS10 in an 18ltr sealed enclosure. Do you still think its a resonance giving wholesale output over what the model predicated? I have a hard time believing room gain is responsible given that you can say best case is +3dB/oct from 100hz down. So I'd like to see a CSD to support your resonance theory but at 16hz I don't think we'll be getting an accurate one anytime soon.
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Old 25th February 2007, 11:58 PM   #405
ScottG is offline ScottG  United States
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Quote:
Originally posted by salas
The sub driven alone, here. The PHL receives a 6db roll off under 200Hz and its in sealed box too.

Underside, with mean level line, the total response with PHL in. One division = 1dB.

I knew that from the start, because that room gain is my room gain. And I don't predict tarantism I just say things are brighter than initially looking and a dipole monster sub with dsp is only one evening woodwork for our thread host.
Small room with a monsterous modal gain between 30-40 Hz? In fact it COULD be similar to Shin's - don't know.

What likely won't be the same is the driver compliance - remember he said flat to 130 Hz (which implies a reduction in spl below that). I'm guessing he spec.ed to Per more extension, as a result he has a lot less spl-level in the midbass then you have.
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Old 26th February 2007, 12:06 AM   #406
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Quote:
Originally posted by ScottG
That is just an spl-thing. If the thing is purposely tuned for a lower spl in this passband then it is equivalent (..or if filtered). Additionally the substantial physical separation will almost certainly alter this.
You've still got worse time based behavior with the ported alignment, add this to a room node and you can see why ported might not be the best choice if that tuning frequency and room node coincide. If your trying to get around that then I can't see the point of an EBS alignment on an 8", especially one that's half decent regarding efficiency. It just doesn't have the displacement/SPL at those low frequencies to be worthwhile to begin with.

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I like the mid with mid reinforcement - I've used it before to good effect. I've also done something similar with tweeters to reach a lower cut-off freq. while maintaining fairly low non-linear distortion.
I just wish there was a sanely priced wide range tweeter that you could cross from 800hz and up but that's just more audio mythology.

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Even an 8" max thing is OK (..like you an many others, I also like speakers that are slim). What I think will have to change is volume (particularly if sealed) which means either additional cabinets in the future or, like a porn star going for the money shot, "go deep".
Perhaps even including a compound configuration.
Scott are you trying to bankrupt me? Compound configuration... 8 drivers...

I think there's also a point where you have to draw a line at the relative cabinet depth in relation to baffle width. Otherwise you end up not being able to stretch your legs out
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Old 26th February 2007, 12:07 AM   #407
Salas is online now Salas  Greece
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Scott:

Why you keep saying that I compare my little 26 litre in total, cheap woofers box, to Shin's 2x35ltr super expensive custom stuff. Its another speaker and room. I say that it can do better with some luck. And I am not a supporter of low bass in small rooms. It sounds awful to me. As for what is being played by a woofer and what is a room mode, its not relevant to the final result quantitywise. Pressure is pressure and we hear it and feel it. If it was only what played by the woofers to be counting then room modes would never present a problem in acoustics. The measurements are honest and you saw I got +8dB what more?
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Old 26th February 2007, 12:21 AM   #408
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Quote:
Originally posted by salas
The sub driven alone, here. The PHL receives a 6db roll off under 200Hz and its in sealed box too.
I had a similar result for the 9" ATC in a 50ltr enclosure.

In 4pi space I was getting a hump of nearly 15dB between 30 and 40hz. After EQ'ing flat I had a response with a virtually flat(no rolloff) response between 30 and 45hz. The 30hz figure was -6dB. Still fairly low output though despite initially looking impressive for what it was (sealed 50ltr, Q=0.5).
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Old 26th February 2007, 12:57 AM   #409
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I know I really ought to try a sub once, on the other hand I dont believe in it, and the added complications
I strongly believe that with the right drivers and setup a simple EQ on the main system will do the trick
Greg(SKA) makes such a slick cheap little thing, but Im not sure if its the right alignment, but it might work and cost next to nothing - a "Linkwitz Gainer" should be right

Shin, its a bit premature I know, but what you need is a passive LCR curcuit on bass drivers ressonanse measured in box - it might also have helped on Perceives instead of dealing with it digitally

BTW, have you ordered bass drivers - I dont understand Per recommending Qts=0.6....I found that about 0.4 would suit 35liter
calculations indicated that higher Qts would need much more than 35liter to work ...
but what do I know, Per is the pro ... even so, Qts=0.6 is close to what the dipole guys use
But its your show, and money ... I dare not take any responsibility
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Old 26th February 2007, 01:39 AM   #410
ScottG is offline ScottG  United States
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Quote:
Originally posted by ShinOBIWAN


You've still got worse time based behavior with the ported alignment, add this to a room node and you can see why ported might not be the best choice if that tuning frequency and room node coincide. If your trying to get around that then I can't see the point of an EBS alignment on an 8", especially one that's half decent regarding efficiency. It just doesn't have the displacement/SPL at those low frequencies to be worthwhile to begin with.



I just wish there was a sanely priced wide range tweeter that you could cross from 800hz and up but that's just more audio mythology.



Scott are you trying to bankrupt me? Compound configuration... 8 drivers...

I think there's also a point where you have to draw a line at the relative cabinet depth in relation to baffle width. Otherwise you end up not being able to stretch your legs out

I question worrying about time behaviour at lower freq.s ..at least from a non-aligned vented system - I've been down that "road". With an eff. driver - not a problem, however lower eff. drivers - yes. In other words even up to 50 milisec.s delay below most fundamentals added onto something the room generates doesn't mean much. Now the linear decay behaviour at vent resonance AND the room mode may cause problems, but because its a very narrow passband for this resonant/linear problem - it isn't something I'd expect (or have found) to be a problem with most recordings (..as long as the resonance was slightly below 40 Hz).

As for excursion.. such a vented system would actually display less excursion in many instances (depending on the recording). Hold that - less DRIVER excursion. In fact, that was the problem with the B&C sub. Vent diameter needs to be large for a given freq. to not run into excursion problems (which effects linear decay and power effects). My bad..

Long story short: IMO its a non-issue.

Don't get me wrong though, this is not an effort to change your mind on the subject.. rather this is just something to keep in the background and perhaps investigate on your own. (..definitely not a suggestion for this project.)

There is such a tweeter! (..otherwise know as "fullrange my @ss")

http://www.ejjordan.co.uk/

It just needs better eff. (especially for a 4 ohm driver), AND a better horizontal polar response. You can even use a first order high pass with it.

8 drivers.. well not AT - thats for sure!

Thats true about the depth thing.. - go too far with the speaker depth and its called a wall.
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