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Old 9th February 2009, 05:06 AM   #2881
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Disregarding any enclosure related limits, the power handling for a multi-driver enclosure is calculated by multiplying the power handling per driver by the number of drivers. Double-click on the Eg box and Hornresp converts watts and nominal impedance to volts for input power.

As others have said, the best way to check your design is to run your hornresp model with the output of your amp (or amps you are considering) at max power (max RMS wattage into your impedance) and look for excursion issues. Hornresp has a max SPL function - when on the SPL response, select tools, then Max SPL. Enter your maximum wattage and xmax, hornresp does the rest. The red portion of the SPL curve mean that you are excursion limited, black indicates that excursion is within xmax.

For example, I am currently constructing a tapped horn subwoofer for my brother. It will use 4 Tang Band W6-1139SI. They are wired series-parallel, so the net impedance is 4 ohms. These drivers are rated at 50 W RMS power, or 100 W music power. When summed, 4 of them will handle 200 W RMS or 400 W music.

According to the spec sheet, the BASH amp is capable of delivering 500 watts into a 4-ohm load. In this enclosure, applying all 500 W into the 4 drivers results in a maximum of 12 mm of excursion within the design's pass-band (30 Hz-100 Hz), but applying 500 W of test-tones to coils that can only handle 200 W will result in thermal failure (the magic smoke comes out). Applying all 500 watts also indicates that there will also be excursion problems below 25 Hz and from 34 to 46 Hz.

Realistically, my brother will probably not be listening to test tones at 120 dB, so in this case, the oversized amp is not a concern, and is actually a benefit, as it will be able to supply clean power for transients without clipping. When set in the final location, it will likely be listened to with the amp supplying less than 1 watt average to the sub, with 10 watt peaks. This will provide almost 100 dB, which is louder than he generally listens. Excursion at these levels is a non-issue (under 1 mm regardless of frequency).
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Old 9th February 2009, 09:18 AM   #2882
AndrewT is online now AndrewT  Scotland
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The mid range power handling will be doubled when you parallel the drivers.

But you're not using them in the midrange.

The low frequency SPL is dominated by Xmax limits, although the TH gets much more out of just about any driver cf. boxed (vented or sealed) driver/s
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Old 9th February 2009, 09:22 AM   #2883
AndrewT is online now AndrewT  Scotland
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Quote:
Originally posted by littlemike
Realistically, my brother will probably not be listening to test tones at 120 dB, so in this case, the oversized amp is not a concern, and is actually a benefit, as it will be able to supply clean power for transients without clipping. When set in the final location, it will likely be listened to with the amp supplying less than 1 watt average to the sub, with 10 watt peaks. This will provide almost 100 dB, which is louder than he generally listens. Excursion at these levels is a non-issue (under 1 mm regardless of frequency).
I suspect you will be even better than that.
Listening with just 250mW to the TH and peaks of +20db (25W) that are passed through cleanly. They will not "sound loud" because there is almost no distortion indicating over-driven, but they sure will have an audible effect.
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Old 9th February 2009, 11:34 AM   #2884
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Hi,
since it is some kind of quiet here in regards to design new suggestions,
I like to contribute what's spooking in my mind for some time:

I modeled a TH which is (net volume wise) similar to the TH-Mini.

As a driver I choose the B&C 12TBX100.

Click the image to open in full size.
Click the image to open in full size.

I think this is a pretty good sample for that you have to put the right driver into the right sized TH
in order to make it work (at least in the simulation).

The typical two resonance peaks are not existing and the it seems
that you do not have to worry about the response above the upper xover frequency.

Some lining inside the horn (as seen in the DTS-50 or the TH-SPUD)
might be required.

What do you think?
Erik
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Old 9th February 2009, 02:14 PM   #2885
GM is online now GM  United States
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Greets!

Yes, as TD has repeatedly stated WRT horn design in general and TH design in particular and as I've 'proved' with some theoretical sims much earlier in this thread, it's possible when the right driver specs are used for the intended app to get a ~ideal maximally flat band-pass response across ~three full octaves with its FL6-Fh6 being 'close enough' to the driver's calculated mid-band efficiency without the sharp phase inversion in its pass-band that HR normally predicts, so factor in the real world smoothing effect of the TH and while some have questioned the validity of at least some of DSL's TH product's claimed performance, I never did.

GM
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Old 9th February 2009, 02:25 PM   #2886
tinitus is online now tinitus  Europe
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So which sub will you use to complement it joke aside, I suspect its intended fore pro use
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Old 9th February 2009, 02:44 PM   #2887
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Another TH with the right specs for the desired BW of course!

GM
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Old 9th February 2009, 06:30 PM   #2888
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@Tinitus
He He... you're right. Good point.

Actually one thing is the interest in the matter, the other is how such
a thing might sound compared to my Tangband 38Hz TH. The later is
based on a heavy mass "car style" sub with weak motor, whereelse the the B&C driver is more or less the oposite of that.

How much might this change the ability of similar TH's in regards to punch and attack (but not max. possible SPL)?

What do the experts think?

Erik
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Old 9th February 2009, 07:17 PM   #2889
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Just an update, in case anyone is interested in my progress. I'm hopelessly stuck on measuring driver parameters, and until I figure out what I'm doing wrong I'll stay stuck.

I've refined my procedure quite a bit, and now within either method the results are basically identical in consistancy but the 2 methods still don't agree with each other.

For example, every single time I run the closed box method I get ~6L vas.

Every single time I run the added mass method I get ~9L for vas.

(Factory vas spec is almost 12L. Qts stays constant regardless of the testing method.)

So it's a simple task of finding my error but I'm WAY behind schedule now with no idea how long it might take.

And no, I'm not buying a woofer tester, this should be something I can do myself.

I won't litter this thread with any more mundane details unrelated to tapped horns, just wanted to say don't hold your breath waiting on me.
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Old 9th February 2009, 08:23 PM   #2890
jm_kzo is offline jm_kzo  France
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Hi Tapped Gurus,

I have been lurking at this thread for a while now but I must admit I still do have difficulties figuring out if tapped horn is a design for me..

For this project , I will soon be looking at a good sub to take over from my (Beyma 10G40 powered) mains from about 100Hz/150Hz down to as low as possible (and as cleanly as possible). Say 30Hz if I'd have to throw a figure...

The use will be 50% HC 50% hifi at "modest" SPLs (home use, not a fan of high SPLs).

I would like the budget to remain... frugal (as it is a word I read here )... Say 150/$ for the driver (preferabily "sourceable" in Europe) and the same for the amp (give or take 50 on the total).

I am going the hardcore DIY route for my mains (starting from scratch) and having the hell of a job at filtering the mains but I must say that I would happily go the "lazzy route" and use a proven design for the sub, this has been too much hard work and I need a rest .

My first actual question :
-do you think tapped horn is design for me ?

Collateral question :
-in a nutshell, what are pros and cons of tapped horn vs. more "traditional" designs (vented). I vaguely remember reading some posts about this earlier in the thread, but i maust say that it is still fuzzy for me and I am not sure there is a consensus (furthermore I cannot find these posts anymore).

My second actual question :
-is there somewhere a list of design "that work" ?

Even a list of designs (speaker + cabinet sketch/plan) with expected/measured output would be really great (like the one from steve71 on page 95).

If you have any other pointers at tapped hor designs in "reasonably sized" enclosures that are proven and useable that would be fantastic.

The design from steve71 where the cabine is about 130 x 80 x 50 cm is OK but a maximum for me. Ideally, I would rather have something that could be a bit taller (more than 130cm, up to 160 cm is still good) and less wide (bringing back the 80cm to 60/50cm).

Many thanks (many many many) in advance for your help and advices.
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