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Trace Elliot Bright Box Question


DiMarco
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You guessed it. One of the four 5" speakers in my brightbox has turned to pulp.
I am looking to replace all four of them wit Monacor msh-115 midrange units that go up to 10khz.

A cheaper option is using Celestion TF0510 units which go up to 8khz which should also be enough. These are only 30w each though instead of the 50w rated Monacors but are 2 to 3db louder at 1 watt then those Monacors.

What do you guys think?
Does anyone know at what frequency the Trace Elliot high pass filter in the brightbox operates?

Thanks in advance, Marco

Edited by DiMarco
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The Monacor isn't sensitive enough. You'd be better off with the cheaper Celestion, which is likely to be better quality anyway. I have a couple of Fane Studio 5Ms (on cast chassis) which last retailed at about £80 each, which will outperform both of them and which I could sell you for less than the cost of a pair of Celestions as I don't need them any more. £40 delivered - how's that? They go up to 8kHz (not that you really need it). However, if you really want to replace all four - get the Celestions.

I can't help you with the crossover frequency, unfortunately.

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Thank you Stevie, I think I'm going to have to go for those celestions considering the costs involved replacing all four those speakers unless I can find another bright box that has at least one working speaker left in there.

I have just found the original specs of the bright box state it runs from 4khz up to 15khz. That 4khz probably means the passive filter in there sits somewhere between 4khz and 5khz which should make it safe to use 30watts speakers summing up to 120 watts for the whole cab.

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Interesting. I know those midrange units and they don't by any stretch of the imagination go up to 15kHz - although they go plenty high enough. There's not much energy from the bass above 4kHz - so I wouldn't worry about power handling. You'll be fine with the Celestions. The original Audax units were quality drivers, but Celestion are making good stuff nowadays and I'm sure you'll be pleased if you fit them.

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The 15kHz stated might be marketing blah. 8k should be high enough indeed as 10 is "treble" on a hi-fi amp. :) (I'm trying to rely on simple logic).

Thomann sell those Celestions for 23 euros a piece. I will go with that almost for certain now.

Thanks again Stevie your help is much appreciated!

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Stuff is worse then I expected. I just took the cabinet apart and it occured to me what has happened with this cab.
Someone tossed it around, threw it on the floor or whatever.

The glue holding the four magnets to the speaker frame came loose on all of the speakers, on the top speaker the magnet + phase plug are separated completely from the speaker frame and the actual coil is ripped in two.

So... one of the previous owners abused this poor little cab.

First the good news:

- The three other speakers still work, I just gotta glue them back together so the phase plug and coil stay aligned in the future.
- I have taken detailed photos of the strangely named "1818 XO2" crossover that's in the brightbox so I can figure out exactly what it does.
- I now know the 5" speakers with phase plugs used in a brightbox are Trace Elliot lsp-s508 and am hoping to get some parameters on them.

By posting all this I hope someone can use this information some time as none of it seems to be online.

Then the bad news:

I payed 100 euros for the sucker so yeah. I got ripped off.

[attachment=150802:foto 1.JPG]

[attachment=150803:foto 2.JPG]

[attachment=150804:foto 3.JPG]

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[attachment=151039:brightbox_celestions.jpg]

Right. Cutout for a Celestion 5" is 3mm larger then that of the original Trace Elliot speakers.
Making those four holes bigger in a sensible way took some time, I did it so now they are conical and everything fits nicely.

Had a solo test run connected to a Trace Elliot AH300-12 and this little fella can go LOUD for its 120w (everything below 4kHz is filtered off).
Speakers are (of course) wired as two series pairs in parallel keeping the load at 8 ohms.
Speaker grille is currently in the garage drying, Not sure if anyone will like the colour I gave it but I do :-)

I think the Celestions will do fine. Can't wait to take the revived brightbox to the studio and test it with the 2x15.

Thanks for reassuring me Steve.

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[quote name='DiMarco' timestamp='1388175879' post='2319227']
[attachment=151039:brightbox_celestions.jpg]

Right. Cutout for a Celestion 5" is 3mm larger then that of the original Trace Elliot speakers.
Making those four holes bigger in a sensible way took some time, I did it so now they are conical and everything fits nicely.

Had a solo test run connected to a Trace Elliot AH300-12 and this little fella can go LOUD for its 120w (everything below 4kHz is filtered off).
Speakers are (of course) wired as two series pairs in parallel keeping the load at 8 ohms.
Speaker grille is currently in the garage drying, Not sure if anyone will like the colour I gave it but I do :-)

I think the Celestions will do fine. Can't wait to take the revived brightbox to the studio and test it with the 2x15.

Thanks for reassuring me Steve.
[/quote]
What an excellent little project. Look forward to hearing how it works out.

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  • 2 weeks later...

It will fall if I use it upright. I use it for more clarity in personal monitoring only. Besides that, Trace Elliot put rubber feet under it so they reckoned this position is okay too...

But I will put it upright next week to see if I notice any improvement. Thanks for the tip.

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[quote name='DiMarco' timestamp='1389286493' post='2332407']
Ow and comb filtering? The 2x15 doesn't go above 4kHz and the brightbox not under 4kHz.
[/quote]For there to be no comb filtering the drivers in the bright box would have to be no more than one wavelength apart center to center. At 4kHz that's 3.4 inches. At 6kHz that's 2.26 inches.
Also, that box should be run down to where the fifteens start to beam, which would be around 1.2kHz. To run them only above 4khz wastes their capacity as midrange drivers. But that only applies when vertical. Those drivers will act as one below their 1 wavelength CTC frequency. Assuming them six inches apart CTC that means below about 2260Hz. Placed horizontally they will beam below that frequency just as if they were a single 20 inch driver, so they'd have narrower dispersion than the fifteens.
[quote]Trace Elliot put rubber feet under it so they reckoned this position is okay too...[/quote]If they reckoned anything it's that the average user would have no idea that drivers should be placed vertically, nor why, and that they'd best show them that way in their advertising, lest people not buy them because they 'didn't look right'. Never forget that what sells most speakers isn't technology, it's looks.

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  • 2 weeks later...

[quote name='DiMarco' timestamp='1390688930' post='2348409']
I tried the brightbox both horizontal and vertical. There is no difference in the sound whatsoever (even when walking up n down the room) by putting it up straight so it is going to remain horizontal.
[/quote]That's not where you'd notice a difference, it's side to side. The reason why can be found here:
[url="http://www.gtaust.com/filter/05/07.shtml"]http://www.gtaust.co...ter/05/07.shtml[/url]

Edited by Bill Fitzmaurice
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  • 3 weeks later...

Hi DiMarco,

Great project.

After trying for ages to get a Brightbox it appears the only way to have one is to do a build. I'm good on the materials and speakers but I'm looking to find a schematic on the wiring, circuit, etc. I can use the photos you posted of the board but some of the values on the parts are hard to see in the photos. I would also need to know where the black and red wires are connected and how to the speakers. Also where to hook up the input in the wiring scheme of things. Anyhelp would be appreciated.

Thanks,
Quentin

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