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PostPosted: Mon May 22, 2017 8:44 am 
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Location: The Neterlands / Holland
After looking and comparing drivers for a cheaper driver to use I ran into this (https://www.thomann.de/nl/the_box_speaker_12_280_8_w.htm) driver and recently (last month) this review was posted "KoenVH, 12.04.2017
Used in Titan 39 and MTH30 subwoofers. Overall its an amazing thomann woofer with lots of power for an unbeatable price. "

Other reviewers are also very happy with it's use in bass horn's like a 1850. It can take a lot more power then the specified 280W (some use 400+W) and it specs are very close to the 3012lf. Biggest differences are a lesser spl response from +/- 75Hz and up and the price: €55 is 4 times cheaper then a 3012lf would cost me here in Holland and would slash total building costs in half.

Specs of this driver I did find on:
https://images6.static-thomann.de/pics/ ... online.pdf
http://www.petoindominique.fr/php/mysql ... 20SPEAKERS (2017 model)
On an other forum I found that the real Xmas is about 8mm not the 3mm or 6mm mentioned.

I'm thinking of building titan39 or slim titan48's with it. (different topic)

What do you know about or think of using this driver?

Edit: typo

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Last edited by Think on Mon May 22, 2017 10:04 am, edited 2 times in total.

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PostPosted: Mon May 22, 2017 9:02 am 
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based on the chart you linked, that speaker only has 3.0mm of xMax. That ain't gonna' cut it in a subwoofer.

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6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."


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PostPosted: Mon May 22, 2017 9:47 am 
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Location: The Neterlands / Holland
That's why I wrote "On an other forum I found that the real Xmas is about 8mm not the 3mm or 6mm mentioned."

Problem is I put this in my notes but can't find the source back, but I'm pretty positive it will be 6mm or more. It was something like: Someone did calculate the xmas based on the other specs (is this posible?) with the formula other manufacturers use and came up with 8.somewhat mm

An other specsheet (the older pre 2017 model) lists +/- 6mm Xmax on page 5 of this pdf https://medias.audiofanzine.com/files/thebox-478376.pdf

6mm Xmas would be usable not? Can you give me an estimation of how much V that would be?
Is it (easy) posible to measure the xmax? Then I just order 2 drivers first and send them back if the xmas is not enough.

edit: my notes say: "wie allgemein fast jeder Hersteller mit [(Hvc-Hg)/2]+(Hg/4) . Rechnet man so mit dem Thomann-Treiber bekommt man über 8mm xmax" which is german and translates roughtly to: when you use the standard formula as other manufacturers do to calculate the Xmax, you will get more then 8mm Xmax

edit2: an other big difference is the crappy documentation on this one! ;)

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PostPosted: Mon May 22, 2017 11:12 am 
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Think, if you are asking if we think the driver will work, it's a gamble. The spec sheet is in French, I believe. My "gut" tells me it will work, but not as well as a recommended driver. It certainly will not take as much power as the 3012LF. I realize that this driver is 1/4 the price as the 3012LF, but would you buy a Porsche Cayman GT4 and put a VW Beetle engine in, would you?

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I know money often seals the deal, but seriously, quality is an investment, not an expense... Grant Bunter
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PostPosted: Mon May 22, 2017 11:14 am 
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With a coil depth of 15mm and gap depth of 10mm the calculated xmax is 2.5mm. Measured at 10% THD it might be 3mm.


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PostPosted: Mon May 22, 2017 1:10 pm 
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2,5mm would be a big no go.

But if I look at this youtube video's the 2,5mm Xmax is probably wrong. But I'm not an expert at all. Can you guys have a look?

https://www.youtube.com/watch?v=MqknzdRjyw8

Edit: removed 2 links, wrong driver. (the box Speaker 12-280/8-A instead of W)

Maybe the chinese mixed the inches up with centimers, then the Xmax would be 2,5 x 2.54 = 6.35mm
The 280W spec is also very conservative (wrong) as I found people writing they use it up to 500W

Can I just order 1 driver and measure the Xmax by pushing the driver in?
This driver might be a well hidden gem.

It's weight of about 22lbs is a downside, but I found so many positive comments about the build and sound quality that I think I just order one, measure it and build a box for it and test it.

//edit: I have often found many bargains and my experience is that price is not an indicator for quality anymore. I have an 11Oz (!) Lepai/Lepy LP-2020A amp for $25 (new) incl shipping and poweradapter :lol: but it sounds way better then my 25lbs? $500+ ax-700a yamaha amp from the days they made quality stuff, which I used before in my living room. Together with a €50 pair second hand monitor speakers with beta 12a drivers and horns in them and a €40 second hand pioneer TS-wx206a car dual bandpass sub with an 8" driver connected to my DBX pa2 and my sound is a lot more detailed and louder then many of my friends (who are musicians) audio systems they have at home.
Knowing how to use stuff correctly is where the biggest gains can be made imho. I was looking for sub placement when I came on this forum the first time about 2 years ago, and knew Bill's advice is right. Which made me look into his designs and became enthusiastic about them.

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PostPosted: Mon May 22, 2017 2:22 pm 
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I can't say if the listed specs are right or not. If they are right the driver's no good. If they're wrong I still wouldn't trust it, because a manufacturer that knows what they're doing wouldn't get it wrong.


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PostPosted: Mon May 22, 2017 4:27 pm 
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Think wrote:
....
Can I just order 1 driver and measure the Xmax by pushing the driver in?
....

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PostPosted: Mon May 22, 2017 4:58 pm 
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Think wrote:
....
Can I just order 1 driver and measure the Xmax by pushing the driver in?
....
It can't be measured that way.


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PostPosted: Mon May 22, 2017 7:51 pm 
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Location: Tilburg, Netherlands
There are enough cheap drivers to choose from. While the 12/280-8w is not a bad driver, it's way overrated on a lot of german fora. It will work in a t39 but I rank it just below the delta12lfa. If someone wants to push his luck by feeding it 400 watts that's his problem. Hans friedrich von hotseflotsen got away with it a couple of times ..... good for him. Buy once, cry once is our motto here. A kappalite 3012lf is a lot stronger and can only handle about 300 watts in a t39 it needs excursion limiting there (at 50volts)

Most of the guys on these fora have never heard a well designed bass horn (with a good driver) so yes they will be pleased with the output they get from a 55 euro driver. That's the main difference between party PA forum (and the like) and this!


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PostPosted: Tue May 23, 2017 8:30 am 
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Location: The Neterlands / Holland
Thank you.

After searching and reading a few hours in understanding xmax I found a great duiscussion @ http://www.avsforum.com/forum/155-diy-s ... -xmax.html

I learned that:
Quote:
BFM: There's more than one way to measure xmax. One is the coil length minus plate thickness divided by two. The other is where THD reaches 10%. The latter tends to give a more generous measurement.

Quote:
diy speaker guy: More recently manufacturers have been adding a "fudge factor" to make for a larger xmax rating out of thin air. For example:


Quote:
https://www.klippel.de/fileadmin/klippe ... MAX_02.pdf : The critical review of the numerical simulation on a fictitious loudspeaker and practical measurements on real loudspeakers
show that the method in AES2-1984 does not provide a clear and useful definition of Xmax. This is mainly caused by some
ambiguities in the wording and more importantly by using assumptions, which are not valid in theory and practice. Clearly,
the measurement of harmonic distortion is not sufficient for assessing all important aspects of the large signal performance as emphasized by Voishvillo [5]. Nonlinearities inherent in transducers such as force factor Bl(x), inductance Le(x) and
Doppler produce significant modulation distortion. The current IEC standard 60268 provides all of the methods required for
assessing these kinds of distortion and for defining Xmax more clearly and reliably. The new definition is based on a two-tone measurement that can be accomplished with straightforward equipment. The resulting distortion measures are also valuable for transducer diagnostics to improve the driver design or select the optimal driver for the particular application.


Xmax values are not comparable between manufacturers and other factors can be limiting performance earlier.

Practical side of things: This cheap driver probably works, but it probably is not going to be very loud.

If I really want to know I have to test it in a box and find the limits.

I really like Eminence Drivers, but prices here are 150% of what you pay in the USA, especially the premium drivers. So I'm looking for something with better value I can buy here in Europe.

@Disco-inferno can you name a few cheap (great value) drivers? (we live in the same country)

Edit: put my location in profile

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PostPosted: Tue May 23, 2017 10:37 am 
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Think wrote:
I'm looking for something with better value I can buy here in Europe.
There are many European drivers that are high quality. B&C, Beyma, 18Sound are just a few.


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PostPosted: Tue May 23, 2017 4:36 pm 
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Think wrote:
I really like Eminence Drivers, but prices here are 150% of what you pay in the USA, especially the premium drivers. So I'm looking for something with better value I can buy here in Europe.


You are not alone.
Everyone outside the USA ends up trying to source other drivers, because only in the USA does Eminence cost what it costs.
The problem with this is, you spend a lot of time looking for drivers, and not building!

Our local importer is asking about $500AU for a 3012lf.

Other builders of Bill's designs have used the Fane Sovereign series in builds in both Europe and South Africa.
For subs, the 12-500LF. You could limit to about the same voltage as the Delta 12LFA IIRC.
That means you would have to build twice as many subs compared to building with either the lab 12 or the 3012lf. eg, 8 cabs with the 12-500lf instead of 4 lab12/3012lf loaded, for the same output.

Driver costs are still cheaper for such an 8 cab build, but then you have to double ply, build time etc etc.

Bill has pointed you to other suitable brand names. Check them out.
Check out the Europe suppliers sticky too (just in case you missed it);
viewtopic.php?f=14&t=4140

In the end, Buy once, cry once...

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Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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PostPosted: Thu May 25, 2017 5:24 pm 
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Location: Tilburg, Netherlands
If you're interested in a good deal on lab12 drivers get on ebay.co.uk search for lab12 and you'll find colosussxb has a great price! £247 for a pair. Genuine eminence!

Lab12's work very nice in a t39 plus, may the need arise you can build t60's with them. :mrgreen:


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PostPosted: Thu May 25, 2017 6:04 pm 
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Location: Tilburg, Netherlands
Bluearan has great deals on a lot of drivers. There are a couple of New drivers from beyma I want to look into and Rcf has a few drivers that have fitting specs and nice strong motors. Both brands have an excellent reputation.

If you find a driver and are not sure, check here first. If you have the driver specs Bill can tell you if it will work.


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