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Old 17th February 2012, 06:29 PM   #1
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Default Extension Subwoofer for Lowther TP1

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Hey guys!

I was wondering if I could get some guidance. I have a pair of DIY TP-1 corner horns using Lowther DX4 drivers. I want to add stereo subs to these for a bit of punch. The TP-1 seem to start rolling off at about 40Hz? I'd like to do a TH design that I could fit between one side and the wall, which would restrict the dimensions to 1024mm high and 566mm deep. Width is is up in the air, but I think I'd like to try a 8" or less driver.

So, first question. What driver? Second, any existing design that you might recommend?

---

I suspect your Lowther horns start rolling off a lot higher than 40Hz.

I also suspect that there is no 8" made that can match the sensitivity of the horn in the octave below it.
A pair of 10" may have sufficient cone area to get up near the Lowther's output

---

Thanks Andrew. As for sensitivity, I see no shame in matching things via active or passive crossover, as if the pair of speakers were to be considered a single multiway speaker.
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Old 17th February 2012, 06:36 PM   #2
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Ill watch this thread intensly as im interested in something similar to woof below my dm302's and whatever fullrange design replaces them.
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Old 17th February 2012, 07:14 PM   #3
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Cool!

I think it's going to be hard not to go with the Exodus Anarchy 25Hz TH design. Flat packs are available, and I could build a small stand to make it fit nicely alongside the TP-1.

Thoughts?
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Old 17th February 2012, 08:06 PM   #4
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They're not small, but do sound rather good, and mine have no trouble filling large rooms (eg, a 20m by 10m function room at a hotel) given 120w/ch.
You'll need fairly aggressive filtering to get rid of the mush >100Hz - I used an active 4th order LR, integrates nicely.

Chris
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Old 18th February 2012, 01:35 AM   #5
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Well, the size is a good fit as it turns out. I could put them alongside the TP-1.

Any alternatives?
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Old 18th February 2012, 01:58 AM   #6
tb46 is offline tb46  United States
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Hi luvdunhill,

The Exodus Anarchy TH was my first thought too, and they have currently a pre-order option @ $68.95; but there is a definite problem with the sensitivity, only 84.7dB. Even in littlemike's TH it only hits 87.6dB @ 50Hz.
I does have good excursion capability though (Xmax=12.5mm).

In the collaborative thread (Post #3279) JLH mentioned the Ciare 10NDH-3 (as he says: it's a bit pricey). It's 10",but maybe something along those lines would get there more easily.

I once modelled the Lowther TP1 with a Fostex FE206E, and ended up with 112db 1W/1m from about 100-300Hz, the model was ~3dB down @ 75Hz / ~6dB down @55Hz / ~10dB down @49Hz (obviously, this is @ 0.5 x Pi / corner loading). Do you have any measurements?

How low do you want this new sub to go?

Regards,
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Old 18th February 2012, 07:58 AM   #7
GM is offline GM  United States
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Quote:
Originally Posted by luvdunhill View Post
Width is is up in the air, but I think I'd like to try a 8" or less driver.
This ~132 L net DSL DTS20 concept using the same two 8" TB W8-740P should have enough peak SPL capability and might can be folded up to fit or at least give you a starting point to modify.

GM
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Old 18th February 2012, 08:23 AM   #8
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Quote:
Originally Posted by tb46 View Post
but there is a definite problem with the sensitivity, only 84.7dB. Even in littlemike's TH it only hits 87.6dB @ 50Hz.
I does have good excursion capability though (Xmax=12.5mm).
I don't find the low sensitivity a problem. The Hornresp sims are (IIRC) in half space. Put them against a wall in a room and sensitivity increases somewhat. Even so, I'd advise active crossovers with the option to change the relative levels.

Even when I paired them with some 98dB@1w 12" coaxials, the THs coped fine - this was in the same 10m by 20m room in which I've tried other experiments with these. Turned it up loud (give each 12" driver around 15w to play with) playing It's Oh So Quiet by Bjork, and the bass was plentiful, no signs of giving up or indeed struggling.

Chris
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Old 18th February 2012, 04:59 PM   #9
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Quote:
Originally Posted by luvdunhill View Post
Well, the size is a good fit as it turns out. I could put them alongside the TP-1.

Any alternatives?
The T-6 is a fair bit larger, and gives up a couple Hz of extension when compared to the Insubnia, but is definitely worthy of mention because of the efficiency. With the Tang Band W8-740C drivers I am using in my T-6s (84 dB/1W), I measured 93 dB at 2.00V, 1 meter, groundplane, from one cabinet, and peak SPLs of over 115 dB at 15% THD as I approached the power handling limits of the driver.

It can be made narrower to properly load a smaller driver, but at 11.75" internal, several 8s and 10s work well in it, and it only takes a single 4X8 sheet of 1/2" ply per cabinet. With a capable 10, bracing would be a good idea, I have not braced any of mine, but I have only built them loaded with 8s so far.

I designed the T-6 to get the most sub I could out of a single 4X8 sheet of ply, and use some drivers I have on the shelf. They have replaced the Shiva X2 tapped horn I made a few years back, and they sound good enough that I've not replaced them yet. I've got several other "large" designs that will certainly replace them in the works, but nothing has been built and tested yet.

Last edited by littlemike; 18th February 2012 at 05:01 PM. Reason: Clarification
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Old 20th February 2012, 08:43 PM   #10
tb46 is offline tb46  United States
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Hi luvdunhill,

Here is a Hornresp model taken from a drawing that fits your space requirements. Drivers are two of the MCM 55-2421 in series. Does that look like something you might be interested in?

Regards,
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