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Old 30th December 2011, 11:32 AM   #1221
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As far as SPL is concerned, there is no maximum limit
I don't need to cross over crazy high or anything - 80, 90Hz is fine
If each cab could reach about 126dB+, that'd be nice - but, I know I'm quite limited (low frequency wise) with the fairly high Fs of these drivers.
I think jbell's Stadiumhorns get the closest for the task - they're just very large. Not his fault - the 3015LFs love a big box to play low, unfortunately.
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Old 30th December 2011, 01:45 PM   #1222
Djim is offline Djim  Netherlands
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The FuryBox (Furysub) isn’t correct in the table. The numbers are based on an old HornResp that I haven’t checked yet on accuracy. If I look to ScreamerUSA’s measurement response on his website it looks more in the order off 42Hz +/-3dB.

With the Eminence 3015LF it is not possible to reach 126dB in a TH with decent low end. The drivers Xmax is mathematically correct but in reality the motor isn’t sufficient enough to make the VC even reach the Xmax. Besides, the cone suffers from serious Dynamic Compression at max load. The so called 'new' version is even worse compared to the 'old' version on which most TH designs are based.

Last edited by Djim; 30th December 2011 at 01:50 PM.
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Old 30th December 2011, 01:50 PM   #1223
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Default DJIM - that's depressing!

When did you become so disappointed by the 3015lf

- did you reach this conclusion in your own testing - if so, what enclosure?
- has data been published about this?

Regards, Ben
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Old 30th December 2011, 02:12 PM   #1224
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by salzburgsoundsystem View Post
When did you become so disappointed by the 3015lf.
- did you reach this conclusion in your own testing - if so, what enclosure?
- has data been published about this?
Regards, Ben
Hi Ben, Several members here on DIY have mentioned the same findings and also for other Eminence drivers like the Lab series. For Europeans I really don't understand why they buy 3015LF's since there are better options for a similar price.
The reason why the RCF L15P200AK sounds less loud in a one on one test is because of its higher Re (this counts for more drivers). But with a decent amp it will be at least 2dB louder in max SPL. Remember most sims are based on 2,83V instead of 1W/1m.

Last edited by Djim; 30th December 2011 at 02:15 PM.
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Old 30th December 2011, 02:23 PM   #1225
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Quote:
Originally Posted by Djim View Post
Hi Ben, Several members here on DIY have mentioned the same findings and also for other Eminence drivers like the Lab series. For Europeans I really don't understand why they buy 3015LF's since there are better options for a similar price.
The reason why the RCF L15P200AK sounds less loud in a one on one test is because of its higher Re (this counts for more drivers). But with a decent amp it will be at least 2dB louder in max SPL. Remember most sims are based on 2,83V instead of 1W/1m.
I got sucked in to using the 3015lf when it was cheap (and when I started building cabinets using BFM plans) - with a discount and no sales tax, they were 137 Euro a piece when I bought them, and I still have 6 good ones.
JBELL - whose designs and advice I have come to respect - warned me not to exceed 200 Watts per driver in my 20 Hz tapped horns. That is an indication of their limitations!

Regards, Ben
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Old 30th December 2011, 02:32 PM   #1226
Djim is offline Djim  Netherlands
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Quote:
Originally Posted by salzburgsoundsystem View Post
I got sucked in to using the 3015lf when it was cheap (and when I started building cabinets using BFM plans) - with a discount and no sales tax, they were 137 Euro a piece when I bought them, and I still have 6 good ones.
JBELL - whose designs and advice I have come to respect - warned me not to exceed 200 Watts per driver in my 20 Hz tapped horns. That is an indication of their limitations! Regards, Ben
Jim is quiet conservative when it comes to powering but I can't blame him. Btw I don't like driving any speaker below its Fs when it comes to PA. I don't say you shouldn't or you can't but it delivers always low max SPL figures and often makes the cone excursion max at the Fs of the driver. That means extra cone losses at max SPL. But the concept of cone losses is not really discussed around here. I always try to design in such way that the -3dB point falls together with the 1/3WL and just above the Fs of the driver. That gives you the max efficiency from that driver and puts the excursion dip on the Fs of the driver. That the reason why the JBells SS15, Xoc1-TH18-2, Martinsson's Tham and Danley's TH118 for instance are so brilliant in my eyes.
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Old 30th December 2011, 02:39 PM   #1227
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Default Fs

Quote:
Originally Posted by Djim View Post
Jim is quiet conservative when it comes to powering but I can't blame him. Btw I don't like driving any speaker below its Fs when it comes to PA. I don't say you shouldn't or you can't but it delivers always low max SPL figures and often makes the cone excursion max at the Fs of the driver. That means extra cone losses at max SPL. But the concept of cone losses is not really discussed around here. I always try to design in such way that the -3dB point falls together with the 1/3WL and just above the Fs of the driver. That gives you the max efficiency from that driver and puts the excursion dip on the Fs of the driver. That the reason why the JBells SS15, Xoc1-TH18-2, Martinsson's Tham and Danley's TH118 for instance are so brilliant in my eyes.
This makes me wonder - are there actually drivers with an Fs low enough to make a really good PA subwoofer that goes down to 20, or is this simply unrealistic? Even expensive 21 inch woofers have Fs around 30 Hz!

Regards, Ben
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Old 30th December 2011, 04:11 PM   #1228
GM is offline GM  United States
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Quote:
Originally Posted by weltersys View Post
Those of us that have actually measured single TH against multiples have found the low corner does not change as it does for FLH in multiples.

Going from one to four cabinets with the same voltage drive gives a 12 dB increase in level, and the increased frontal area provides greater directivity, which can add even more level on axis.

Those level increases make it easy to think the low corner has gone lower, but so far I have not seen any actual measurements showing that to be the case.

Art Welter
OK, just so I'm clear since I still haven't built/measured a TH; you're saying that this simmed ~6 Hz downward shift of a single Vs 2S-2P and the ~12 Hz Vs 4S-4P [eg = 2.83 V, 2 pi] is all due to increased on -axis directivity? Or is HR being overly optimistic?

TIA,

GM
Attached Images
File Type: gif 1 Vs 4 TH combined response.gif (16.0 KB, 286 views)
File Type: gif 1 Vs 8 TH combined response.gif (16.1 KB, 283 views)
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Old 30th December 2011, 04:23 PM   #1229
tb46 is offline tb46  United States
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Hi Y'all,

You have been busy, just some observations:

1. Post #1217: There was an update to the Furysub drawing: see Post #535 for the updated drawing LIVE SOUND Specific Tapped Horn thread..., there is a lot of subsequent discussion; see #563 for my attempt at an AkAbak simulation; there never was any resolution as to the lack of agreement between screamer's measurement, and the Hornresp SPL derived from the drawing.

2. I don't believe that a tapped horn - optimized for the low end capabilty of the driver - ends up with the driver's Fs below the speaker's passband. On the contrary, the Fs should be in the passband if you are looking for low end extension. The 3015LF just happens to call for a big box (see stadium horn), and it works just fine as long as the box is big enough. The SS15 is optimized for a reduced low end and high output, but not for the driver's low end capability (that's where you get to the stadium horn, or larger).

3. It may just be my mistaken impression, but I have noticed a tendency in the PA world for people to overdrive and just generally abuse their speakers. Keep the power and the Xmax below manufacturer's ratings, and use adequate low-cut filters. I don't think jbell is conservative (well, he may be) just technically correct.

4. As an alternative for Crescendo: how about going the route that justin went with bjorno's T-TQWT? Maybe as a dual, a very easy build, and not as big as a tapped horn. Doesn't look like that would be hard to try.

Happy New Year Y'all. :-)
Attached Images
File Type: jpg 3015LF_Dual_T_TQWT_Input.jpg (37.8 KB, 250 views)
File Type: jpg 3015LF_Dual_T_TQWT_SPL.jpg (32.1 KB, 247 views)
File Type: jpg 3015LF_Dual_T_TQWT_Box.jpg (20.9 KB, 244 views)
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Old 30th December 2011, 06:08 PM   #1230
Djim is offline Djim  Netherlands
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Hi Oliver,

I quote myself:
I always try to design in such way that the -3dB point falls together with the 1/3WL and just above the Fs of the driver.” To me, that means the Fs falls between 1/4WL and 1/3WL and is therefore within the bandpass.

I also stated:
I don't say you shouldn't or you can't.
It’s not like a golden rule but 'accidentally' all designs with an sensitivity of >98dB and with usable volumes, seem to have it that way, Danley's notorious TH118 included.

As far as PA people, 'they' just don’t like T/S parameters that don’t hold up in reality. Driving your LF drivers up to Xmax is not a luxury but a common thing for PA. This is where PA and other sectors differ, I think. Every respected PA driver manufacturer uses certain over excursion possibility that is in ratio with the Xlim and peak power (crest factor, AES standards). Respectable Pro Sound System manufacturers don’t support brands that don’t meet up with these standards/expectations. Of course that is a different view from many DIY's for whom price/performance is often more important. Just a matter of differences and for each one there is something to say.

Happy new year to you also and all DIY members!

Last edited by Djim; 30th December 2011 at 06:23 PM.
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