Floorstander w/ Vifa P13 & D27 based on Wiki?

[nrgy]

I have a pair of Vifa P13 and D27 speakers lying around from a project I planned to undergo last year but never got around to it. I am interested in doing something with these again...and am looking at building some floorstanding speakers. First off, I planned to build the Wiki project using the single cap on the tweeter. I would still like to go this route as I am not comfortable with building complex crossovers, and I would rather concentrate my efforts on building the enclosure.

My question is, the Wiki was intended for a bookshelf enclosure...if I try to use this design in a much larger floorstanding enclosure, how will this affect the sound? Also, can I expand this idea into a MTM or TMM design using the D27 with the cap, and 2 P13s running fullrange?

Once again, many questions for a first timer. Thanks.

[planet10]

ChrisB used these in a daline, but even better performance can probably be had from a line optimally designed with MJK models (maybe an ML-TL)

dave

[clm811]

Just saw thread.

Have built several speakers using these drivers. I found the best advice on using the p13's from Lynn Olsen at:

http://www.nutshellhifi.com/Arieltxt1.html#td

[rabbitz]

I have to agree with dave as a TL such as the TLb would be the best way to use those drivers in a floorstander as the design as is would not be suitable.

x. onasis who built and tested the different variations said he was amazed at bass in the TL version.

BTW, the Wiki has been updated with thoughts on a larger bookshelf box (no good) using the same number of drivers as well as some alternative series crossovers.

An option has been added in the Wiki of a vented box using a 0.5 woofer on the back for BSC which IMO is better way to use the second P13 than a MTM or TMM with all the drivers on the front. This could be adapted to a floorstander with the excess volume closed off. It still would not be as good as the TL IMO as it could not compete with the bass extension, but would still make a very nice speaker.

An MTM needs a more complex crossover to be successful and the TMM could be done with the bottom woofer used as a 0.5 and not fullrange.

Ah... build them all and let us know

Cheers

[fazman]

I can't see there being a real issue using the second p13 as the .5 woofer in an MTM arrangement.
I use 2 p17's in an MTM configuration and using the bottom woofer as the .5 for a 2 and a half way seemed to work pretty well.
This might cut down on some possible lobing issues.

If you keep the crossovers outside the enclosures while you experiment it's worth the effort to try
Whatever you end up doing the p13 will need some sort of BSC even if you are using 2 per speaker because they can tend to get a little midrangy if not compensated for

Best of Luck

[planet10]

I'll chime in with Rabbitz here... the best place for a 0.5 woofer is on the back of the cabinet where its phase roll as it rolls off is in the shadow of the cabinet and not fighting the other driver.

dave

[rabbitz]

I tried the 0.5 woofer on the front in a TMM arrangement and on the back which was far better IMO and really helped the speaker perform. An elegant and efficient way to solve BSC as you only get back what you lose when done right and the SPL of the speaker benefits compared to doing it in the crossover where you reduce the speaker SPL to bring it in line with the BS. The benefit is you need less power to make them sing.

If the little D27 / P13 in the Wiki is used close to a wall, no BSC is required but be aware that it is light on the bottom end but majors in the mids and upper bass. Soon as you bring them into the room away from the wall, then BSC is a must. There's a great graph on the TLb pages that demonstates this by having the second woofer on the back as well as showing where the BS starts on the monopole. BTW, the complete article on the TLb is a worthwhile read.
http://homepage.mac.com/tlinespeaker...ges/Fig52L.gif

If the top end is too bright, then it can be brought down with an L-Pad or single series resistor which would need a different single cap value. The alternative series xo's suggested take care of that and can be tweaked.

[fazman]

rabbitz and Dave...
I don't doubt that the woofer on the back of the speaker is a more effective way of baffle step, I tied it myself and it worked well but it may not be solution for every situation.
Placement to the back wall now becomes more sensitive because of this and in my experiments , the woofer on the back provided me with pretty much all of the 6 db baffle step which was a little too much. You may require only a moderate amount of BSC in which going the .5 woofer on the front may provide a little more flexibility.
There are also dispersion advantages going MTM if the speaker is going to be used for both home theater and music so if this configuration is desired then you could do effective BSC if you needed to.
Just wanted to give him an option if in fact this style of speaker was desired thats all.

[planet10]

Originally posted by fazman
Placement to the back wall now becomes more sensitive because of this and in my experiments , the woofer on the back provided me with pretty much all of the 6 db baffle step which was a little too much. You may require only a moderate amount of BSC in which going the .5 woofer on the front may provide a little more flexibility.

In an x.5-way speaker the amount of BSC provided should be no different if the driver is on the front or the back. On the back thou, placement close to a wall can be more problematic.

There are also dispersion advantages going MTM if the speaker is going to be used for both home theater and music

A true MTM pushes the required XO lower than i like to think about. Many are more about marketing than anything else. I did the math last night -- 2 3" Auras, + a tweeter small enuff that if i offset the tweeter i could still get the M baskets to touch, and the interdriver distance suggested an XO less than 4 KHz. With the P13 and the D27 it will be alot lower than that -- lower than the tweeter can really go i bet.

dave

[jleaman]

Hope you don't want any Bass for this design..