Zaph ZA5.2 Ported/Vented 7L (.25 cf) Design

[pirate121]

Hi,
I've decided to make Zaph's ZA5.2 speakers as my new computer speakers. Because they're computer speakers they need to be nearfield.
On the speaker website (Zaph|Audio - ZA5 Speaker Designs with ZA14W08 woofer and Vifa DQ25SC16-04 tweeter) for making the ZA5.2 nearfield monitors, Zaph recommended this: "All of this in relation to the ZA5.2 would mean the following tweaks: using the reduced BSC crossover, using an enclosure of .25 cu ft, a front mounted port of higher tuning, maybe 55-65 Hz depending on taste." And on the site there's a diagram for for the sealed 7L (.25 cu ft) ZA5.2 enclosure, but not for the vented.

As this is my first DIY speaker I decided to choose a good, proven design and not to modify it. Although I don't know where the best place to put the port tube is.
So my question is what would the Zaph ZA5.2 vented 7L design be? Where would the port go?

This was also mentioned: "If you choose a smaller enclosure, be sure to keep the same baffle width and tweeter location relative to the woofer and nearest edge."

Thanks,

Andrew

[hpolkerman]

You'd best put the BR on the front, if you're close to the walls/monitor and so on. The bass-extention with my RS125S-8 dayton+XT25SC90's are quite high. So tuning about 55-65Hz should do the trick, of you're close to a wall/monitor, front BR.

Now the placing of the BR is totally up to you, wherever you can fit the BR in in your plans... don't forget a slot is also possible ( if the room for a round BR isn't an option)

[pirate121]

Hi, thanks for the reply

Sorry, I forgot to mention that I'm buying this from madisound (Zaph|Audio ZA5.2 TM 2-Way, Pair from Madisound) which comes with a 1.5" port which flares at the end making it 2.95" (75mm) on the front baffle. This presents a problem as it is only able to fit if I move the tweeter accross, but I'm not sure if this will change the sound? (The normal sealed design has the tweeter directly above the woofer with a gap of 0.35" (9mm) and 0.58" (14.75mm) from the edge.)

Well anyway, I had a crack at a diagram (http://img717.yfrog.com/img717/3030/za52ported.gif) and I was wondering if this will be alright? As instructed, I kept the tweeter location the same between the nearest edge and the woofer.



Is the location of the port alright? It seems close to the edge (and the tweeter), although that's the flared end and the actual port won't be that close.



hpolkerman, by slot do you mean just a hole in the mdf to vent the speaker? It would certainly be easier, but what would the difference in sound be and would you still be able to tune it to 55-65hz?

Thanks

[giralfino]

I would opt for a rear mounted vent, right behind the tweeter. A vent needs only a small amount of space (some 10 cm) to work properly.

Keep in mind that the xo depends also on the driver position on the baffle, so you should use the same layout of the original design - it is important the position from the top of the enclosure, please note that the layout is the same for both the vented and sealed versions.

Ralf

[pirate121]

Rear mounted vent would be a lot easier, but I was avoiding that as the speakers will be reasonably close to other objects and the wall and I'll be sitting close to them (nearfield), and from what I've heard, rear mounted vents aren't great for this particular application.

I'd like to keep the same layout to the original design, but this particular port will not fit any other way. Would using a smaller or non flared port be the best way?

Thanks,
Andrew

[giralfino]

I missed the explanation why it is advisable to use front ported vents for a nearfield application.

In this case use the Zaph layout and add 2 small (1" ID 4" long) ports like those of the Wharfedale 9.1.
They should fit easily between the woofer and the bottom edges.

Ralf

[preiter]

A vented design requires more internal volume than a sealed design. That is why there is no 7L vented design. You are going to have to choose between less bass extension (sealed) or a larger box (vented).

If you don't have a large enough desk for the larger box, try the sealed design with a subwoofer.

As this is your first project, I would take one of the designs and build it exactly as specified. Don't try any modifications until you know a whole lot more about speaker design.

[pirate121]

Yeah I wouldn't even think of doing a 7L vented design if it wasn't for the designer specifically saying that for nearfield use of the ZA5.2 it is best to use a vented 0.25cu ft (which is 7L) enclosure of higher tuning (55-65hz). I don't know all that much about speaker design which is why I'm asking here, hoping more experienced people can help!

I wouldn't mind adding a subwoofer, however, powering it seemed to be too expensive and/or impractical (awkward access to a sub plate amp)

I don't know that much about ports. Will the sound be altered by using a smaller port/multiple ports/slot if still tuned right?

Thanks,
Andrew

[giralfino]

I don't know that much about ports. Will the sound be altered by using a smaller port/multiple ports/slot if still tuned right?

The tuning depends on the combination of volume of the box and number, length, diameter of the port(s). With respect to a base port, tuning go lower with a longer port, and higher with a wider port, and also if you increase the number of ports. Wider ports have the advantage of a lower air speed into the port thus minimizing the risk of whistle. The same apply with more ports. The goal is to have the air speed lower than roughly 25m/s. If you exceed this value you hear the noise.

This is the reason I suggested 2 small ports, instead of only one. 2 ports of 1" ID and 4" long in a 7L cabinet give a tuning in the 60Hz area. I suggest also to download Unibox (free, and easy to use).

Ralf

[pirate121]

Sorry for late reply, but yeah 2 small ports sounds like a great way to go for this.

Although I decided not to make this for computer speakers as they're a little large and I'd prefer a more 'coloured' sound which I personally think is better for the style of music I listen to (Rock and such).
Designing my own 2.1 system instead.

Thanks for your help,
Andrew