Proac 2.5 clone few questions ???

[kimel]

Hello,
I decided to build the Proac 2.5 clone. This is going to be my first DIY speaker project.

I am going to build Troels Gravesen 8535+9500 model.

I have few questions:
1) Troels writes a warring on page 25 of his PDF file:
http://home1.stofanet.dk/troels.grav...ne%20paper.pdf
Troels say that new models of the 18W/8535-00 were “heavily coated on the rear of the membrane”
And suggest a modification to the crossover should be made.

Does anyone know what kind of modification should be made?
How would the sound be without any modification?
Does anyone knows if I can order the right driver (not coated) ? dose it have a certain serial number?

2) I checked in local carpentry workshop, and I might not have the exact width.
How important is the MDF width?
Does 19 mm MDF instead of 20 mm makes a sound difference?

3) Also does you know any site that shows step-by-step box building for this clone?

Thanks
Tsachi kimel

[tktran]

A1) A re-design of crossover is required because of the 8535's early high frequency roll-off. A 2Khz to 2.5Khz crossover point is suggested, however Troels has not made this crossover.

Unless you have measuring equipment and time to learn about crossover design you'll have to live with the standard XO.

The dry look "non-coated" drivers are not available, and are not differentiated from the current batch of "coated" drivers.

The sound of the 2.5 clone and it's derivatives have been covered. I suggest you search this forum.

A2) No difference worth worrying about.

A3) No. A detailed construction article really is boring to write (and read). With something like the 2.5 clone boxes, cabinet plans are all that is necessary. Do some planning before you cut your wood and be prepared to do some research/learning about woodworking. This is half the fun.

Bite the bullet. Do more reading before diving in.

[phibes]

Hi Kimel,
Do another search on the Proac 2.5 clone, there is an absolute load of information on design, construction and particularly x-over modifications. The coated driver I believe you'll find was a batch issue problem and not any particular way they were being manufactured.........plenty of disclaimers out there in this regard!!
As far as 19mm to 20mm mdf is concerned, it will not make one iota of difference.........I'd recommend you look at retaining the same internal box volume and use 25mm or 33mm mdf instead.
Cheers,

[kimel]

Thanks for your replay , I will do some more reading.
Anyhow I ask at http://www.audiocomponents.nl/
And the guy told me that :
"The 18W8535.00 has an impregnated membrane, so it's not
coated on the rearside"

[tktran]

kimel,

regardless of whether any dealer claims whether it is "coated" or "uncoated" etc etc, the fact is that 2 batches that Troels had were different. And since he developed his crossover with the first batch, his warning is that your results may vary.

Purchased in Sept 2003, I was assured that my drivers were claimed to be "uncoated" by my dealer,

Coated or not, after I took a photo it looked just like the one with the shiny rear cone in Troel's PDF.

[Eran]

Hi Kimel,

I'm also planning on building the ProAc2.5.

Do you have any expirence with importing to Israel(VAT, costumes?)

Did you look into similar designs? The Eros, Human 88-41?



Thanks

[kimel]

Hi Eran,

I must admit I took only a short glance at other project.
I chosen this clone b/c I heard both the Proac 125 and 15D at a local dealer and I liked there sound, I really likes good stage sound.
I read many review of the clone sound and I guess I will also like the clone sound.
Regarding VAT/costumes I asked at the costume department and I was told that when the parcel arrives, I would be charge for taxes that is 30% – 40%, which include all taxes together ( VAT, import etc…).
It was hard though to get a proper answer, I guess only when the parcel arrives ill know for sure.

Tsachi