Extremis MT cabinets done (pics)

Grahamt · 8th February 2005, 03:17 PM

Here is one of my MTs. They are 34L tuned to 25 Hz. They are about 10" by 17" by 21". They are made from .75" ply and 1.25" butcher block. I have some AutoCAD drawings if anyone is interested in the construction. The finish is spray on truck bed liner, a very forgiving, durable finish.

The tweeter is the LPG 26T and the woofer is the Adire Extremis 6.8. In my room these are as loud at 20 Hz as they are above 100 Hz.

The crossover isn't done yet. A friend is working on it in his spare time. It will be a 4th order Linkwitz Riley with cauer elliptic filters bringing the attenuation to about 8th order and crossed over below 1.5 kHz IIRC.

Grahamt · 8th February 2005, 03:18 PM

More pics

Grahamt · 8th February 2005, 03:20 PM

Side

Taco · 8th February 2005, 03:21 PM

Wow, that tweeter looks like if it is modified. The top-end of those Extremis woofers are not that nice, so I think an x-over of 1500Hz is a good starting point. Also that cabinet looks deep.

Grahamt · 8th February 2005, 03:21 PM

Back

Grahamt · 8th February 2005, 03:23 PM

Quote:

Originally posted by Taco
Wow, that tweeter looks like if it is modified. The top-end of those Extremis woofers are not that nice, so I think an x-over of 1500Hz is a good starting point.

Yep. It is modified using the JonMarsh method. Stuffed the pole piece and centered the voice coil.

The cabinet is deep to get the low frequency efficiency and to allow for a port long enough. The 2" port I used is about 12" long, and a 3" port that I may use would be close to 16" long IIRC. Also there will be hardly any reflections off the back wall of the enclosure.

gary f · 8th February 2005, 03:49 PM

I think the 26T tweeter don'T have a good reputation for low crossovers below 3000 Hz. The X max is 0mm because the voice coil is the same length as the gap so don'T expect it to play low.

F

Grahamt · 8th February 2005, 04:06 PM

According to the crossover designer, the low crossover point should be okay because the attenuation is so high. He is doing distortion tests on them to see how low we can go. Hopefully the modifications will help.
Here is an example of the crossover.

Radian · 12th February 2005, 11:45 AM

Hello Graham,

How is the sound of the modified LPG?
The 25FA was used in the highly regarted Silverline Sonatina I +II.
Solen has them for $17 on sale and I am really tempted to try them out.
But if the version you are using is better I will spend the extra $$.

Cheers,
Klaus

Grahamt · 12th February 2005, 12:06 PM

Hi Klaus,

I have not listened to the tweeter much since the crossover is not done. From the little listening I have done, they sound pretty good. If you want see the mod thread here it is:
http://htguide.com/forum/showthread.php4?t=11305

Sorry I could not be of more help. When the crossover is done I will know more.

12th February 2005, 11:45 AM	#9
Radian diyAudio Member Join Date: Jun 2004 Location: Wiesbaden	LPG tweeter Hello Graham, How is the sound of the modified LPG? The 25FA was used in the highly regarted Silverline Sonatina I +II. Solen has them for $17 on sale and I am really tempted to try them out. But if the version you are using is better I will spend the extra $$. Cheers, Klaus

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8th February 2005, 03:21 PM	#4
Taco diyAudio Member Join Date: Nov 2002 Location: Place in the Netherlands	Wow, that tweeter looks like if it is modified. The top-end of those Extremis woofers are not that nice, so I think an x-over of 1500Hz is a good starting point. Also that cabinet looks deep.

8th February 2005, 03:49 PM	#7
gary f diyAudio Member Join Date: Aug 2003 Location: Quebec city	I think the 26T tweeter don'T have a good reputation for low crossovers below 3000 Hz. The X max is 0mm because the voice coil is the same length as the gap so don'T expect it to play low. F

8th February 2005, 04:06 PM	#8
Grahamt diyAudio Member Join Date: Mar 2004 Location: U of Waterloo	According to the crossover designer, the low crossover point should be okay because the attenuation is so high. He is doing distortion tests on them to see how low we can go. Hopefully the modifications will help. Here is an example of the crossover.

12th February 2005, 12:06 PM	#10
Grahamt diyAudio Member Join Date: Mar 2004 Location: U of Waterloo	Hi Klaus, I have not listened to the tweeter much since the crossover is not done. From the little listening I have done, they sound pretty good. If you want see the mod thread here it is: http://htguide.com/forum/showthread.php4?t=11305 Sorry I could not be of more help. When the crossover is done I will know more.

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