2way with CA18RNX or ER18RNX

[kaiser38]

Hello,

I'm French. Here We can fin the SEAS products at a good price.

I saw a loudspeakers, ProAc 130. It seems to use a CA18 boomer and a vifa DX25 tweeter. It costs 1500€ (2000$) !

I saw the zaphaudio website, with the little SR17 with the ER18RNX and 27TDFC.

I would just build a similar speakers, but with a difference :

- I want a floorstanding speaker. Apparently, the ER18RNX (or CA18RNX) allows a 15 liters cabinet (little floorstanding)

And, is it a good idea to replace the 27TDFC by a 29TFF/W or better
T25CF001 ?

Lastly, somebody use ER or CA18RNX with a simple xover 6db, for example ?

Thanks a lot

Julien

 

[tktran303]

Build the SR71 like the way it was designed. You can build a floorstanding with same internal dimensions, or slightly larger cabinet (16-20L) without degrading performance too much.

But the chosen crossover design and drivers are fixed. Don't change one or the other.

 

[peter_m]

What "tktran303" said!

Peter

 

[kaiser38]

OK, excellent !

I think that i'll go to order the drivers and components !

What are the difference between the zaph audio design (little bookshield speakers) and a floorstanding with 15liters ?

More bass ? or not ?

 

[kaiser38]

i dont' understand peter ...

Can I build a little floorstanding speakers for the SR71 or not ?

The question is simple !

thanks

 

[sdclc126]

IMO any speaker can be a floorstander - just build it the height you want but keep the baffle width and internal volume the same.

P.S. - Regarding the T25CF001 Zaph says "Slightly expensive for what you get."

 

[Dave Bullet]

As softdome said.

Build the SR71 into a tower but use the same baffle width and tweeter and woofer offsets from the top / sides of the baffle. Design the height of the tower to place the tweeter on axis at listening height / seated position.

Keep internal volume the same by creating a false partition so that the bottom part of the tower becomes a dummy stand effectively, venting port on the top part. Baffle diffraction and step will not be affected significantly by a longer baffle.

Cheers,
David.

 

[kaiser38]

OK

the madisound cabinet is 14 liters,

I'll try to design a floorstanding cabinet with approximatively the same size.

There is just a problem with the baffle step...

Anybody can help me ? Should I modify something in the crossover ?

I saw the website of J. KIM, he proposes another xover, but his version is very different...
I would prefer use the John "zaph" version...

Thanks a lot

 

[jerome69]

Hello boy

Don't touch anything , keep the design at is, building loudspeaker requires skill and tools.

If you want a floorstander just make the cabinet longer keeping the same width, depth and internal volume.

 

[Andy G]

I have nearly finalised a speaker using the ER18 and 27TDFC

http://members.optusnet.com.au/~gradds55/Jarrah_stand.jpg

It uses an AR series type of crossover (a different x-o again), which works beautifully.

 

[kaiser38]

somebody can describe the listen results of this speakers ?

is there good bass ? how is the midrange ?

thanks !

 

[peter_m]

Andy Graddon,
do you have more details on you speaker build? Is it a TransLam?

kaiser38,
you can make the SR-71 into a floor stander as long as you don't modify the width of the cabinet. No need to modify the x-over as long as you don't change the cabinet width and don't change the driver location on he baffle. As for internal volume, you will need to put a barrier to reduce the internal volume back to the 14L of the original design. From what I understood, 14L was basically the available volume of the Madisound enclosures and Zaph might have hinted he would have preferred slightly larger volume at 16L but that is splitting hairs.

From what I've read it's a great sounding speaker. Just might build a pair some day.

Peter

Edit: http://htguide.com/forum/showpost.php4?p=411191&postcount=89

 

[Jay_WJ]

Actually, "you can freely change the baffle height---simply keep the width as specified" is sort of a general guideline because it doesn't make a big difference in general. But the fact is, not only baffle width but also height affects baffle step. In the case of SR71, a tall baffle should make a noticeable difference because the original design has already incorporated real "full" baffle step compensation. This is shown in the following sim result in my web page:

Effect of tall baffle on ER18RNX 2-way response

My crossover is not "very different" from Zaph's. Mine just has a little bit (1 dB) less BSC, and a little lower (1.55 vs 1.75 kHz) xover point than his.

If you're interested, here's a review from a Polish person who used my crossover for his build (27TBFC/G version):

http://www.diyaudio.com/forums/showthread.php?s=&threadid=123397

He was very satisfied with the result.

-jAy

 

[Andy G]

Andy Graddon,
do you have more details on you speaker build? Is it a TransLam?

Yes its a translam, using solid "Jarrah" timber (from Western Australia). Built up using curved staves for the sides and some flat plank for the top an bottom. This is lined with 'caneite' (sugar cane board) then a layer of barium rubber, then foam, and some wadding. Very inert, and heavy !!!

The highlight is a 8mm layer of Tasmanian Oak.

The narrow back is actually 1" mdf (Jarrah is quite expensive and I didn't really want to use it for the back), and the detachable baffle is also 1" mdf.

 

[kaiser38]

Hello,

Jay, I saw the curves on your website

Why do you down the xover point from 1750hz to 1550hz?

Could I use your BSC to compensate the height of the floorstanding, and keep the originaly xover point of John's design

A question, to make my cabinet :
Somebody have the exact width and size of the madisound cabinet in centimeters ?

Thanks,

PS : I don't understand the sentence in the xover plan on the zaph website. What does mean "this resistance is part of the inductor" ?
It means that I don't need to buy the R3 & R8 resistance (red color) ?

 

[Jay_WJ]

Why do you down the xover point from 1750hz to 1550hz?

The answer is also in my web page.

 

[kaiser38]

OK I saw !

I don't know what I'll do.

Now, I try to design the cabinet for my project.

 

[crazyhub]

Actually, "you can freely change the baffle height---simply keep the width as specified" is sort of a general guideline because it doesn't make a big difference in general. But the fact is, not only baffle width but also height affects baffle step. In the case of SR71, a tall baffle should make a noticeable difference because the original design has already incorporated real "full" baffle step compensation.

I agree. From a previous experience with Ellis 1801b, standed and floorstanded (same drivers location, same width, same internal shape and volume, only the baffle was prolongated under the woofer), listening results were quite different.
Edit: the b version of the ellis also used a big (full?...)BSC filter.

 

[kaiser38]

I would like to have the opinion of john about the really diffence between the kit with MD14 enclosure and floorstanding cabinet.

In his website, we can read this : ".

You may be able to build a floorstanding version of a stand mounted system, provided the width and driver positioning relative to the top and sides is close to the original. In this situation, there will only be about one dB of variation in the frequency response

Lastly, Do you think that the depth of the enclosure are important or not ?
The internal depth of the MD14 enclosure is 8.75", I would reduce this to 8" (less 3/4")

If it's a problem, I won't do this !


thanks !

 

[sreten]

Hi,

FWIW you should use all the information available to you.

i.e. that from Zaph and WJ.

The crossovers are barely different and WJ extends Zaphs options.

A floorstander will afffect BSC which can be ameliorated by making
it somewhat narrower, but more likely choose a c/o option for this.

The floorstander does not have to be 14L. Around 17L is optimum
and basically 14L to 20L will all work with the same dimensioned
port, which will adjust automatically for the different cases.
The larger sizes, 17L to 20L will give drier but more extended bass.

As the cabinet size is not large for a floorstander :

Consider reducing hieght and an angled baffle to point the
tweeter towards ear hieght at the normal listening distance.

Consider a closed off section in the base to be filled with sand.
This could also house the crossover.

/sreten.