Vifa P17/D25 floorstander + XLS subwoofer finished!

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Err...

David that's actually a carport. :)
We swept up after each job, because the cars have to go back in.

Considering the low cost of the drive units, I think they're a decent speaker. It's a bit difficult to evaluate them critically because they're in a room I'm not familiar with (modern decor, reflective surfaces, not unlike a typical kitchen).

The owners seem very happy with them. I think that's more important considering it was his first DIY speaker project.
 
They look very good :)

I would be afraid of making ported anything in australia. Only thing i see about australia up here in Canada is that all things that slither crawl fly and swin can kill me. SO for your next DIY build a speaker that has self defense lasers for wasting FST's (flying and stingy thingys)

I hope they sound as good as they look.
 
Hey guys, Thought I better start posting instead of getting my friend (tktran) to always post on my behalf.

The Vifa P17/D25 floorstanders are working but I still need to sand and finish the veneer. The XLS sub is also finished, but a few days ago some smoke came out of it after i was driving it quite hard. I quickly disconnected and pulled it apart. The driver was fine and the amp was barely warm with no char marks/poped caps. Very bizaar and hassn't happend since.

I am very pleased with the sound from the sub/floorstanders together, but there seems to be a room resonance around 100-200Hz. Any ideas of how this could easily be fixed? I can't move the sub around much unfortuately.

http://kram0.com/gallery
 
Mark brought his subwoofer over to my place, and it sure sounded great. I didn't notice any boomy notes or resonances, but then the room is also a lot larger and the placement was totally different (well clear of walls)

Unfortunately I don't think there are easy solutions to this. At the end of the day, Audio is Acoustics. The source/amplifier/speaker is the playback part of the chain ie. performers, but the rest of it is the room, ie. venue.

Have you tried moving that subwoofer to the opposite side, on the left of the couch facing the tv?
 
The speakers have been finished! At last a project that has made it out of the garage finished leaving behind numerous other half completed projects. Might put another couple of coats of Danish oil on though. The Organoil Danish Oil I used smells really nice: piney/citrousy like some cleaning products.

As for Madmike2's comments on creepy crawlies: I had never considered that. Hopefully the handful of resident redback spiders (dangerous) living in our garage haven't migrated to the padded confines of one of my speakers.

As with all projects something always goes wrong. With my excitment of a finished project I accidently mixed up the wires from amp to sub to speakers and hooked up the left channel to the right channel. Short circuit protection kicked in but the right channel blew. Have to live with mono music for a fews days until I fix the amp. :(

I would like to thank Dennis Murphy for his crossover design and driver placement design.

A completed photo and my speakers & crossover blueprints at:

http://kram0.com/gallery
 
I have a digital equilizer I made a while back that I could setup. Would some sort of notch filter be the best way to remove the resonance? The equalizer I have uses a TAS3002 IC from TI. They actually provide software where you can input the actual measured response and desired response (flat) and it programs the IC with the desired filter parameters. However that requires me to make/buy some sort of accurate microphone setup. :(

What are room resonances normally? Just 1 peak? Or are there many siginificant modes ( muliples of the room length or something) Could I make some small analog variable notch filter? Would that surfice?
 
Mark, there are a number of modes in any room, you need to measure to know. Normally they occur up to about 200 Hz. My room is a medium sized room 4 x 5m with 3m ceiling and I have a peak around 35 Hz and a dip around 80 Hz that stand out the most.

Here is a screenshot of the eq I use to get it flat.

A mic is not that hard! You can either do a diy mic with a diy preamp. Or you can get an inexpensive Behringer ECM mic for about $100. You can build your own for about $30. That is AUD. Preamp is another matter.
 

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An alternative way to use the P17

Greetings all,

Long story here, but I have just added a free P17 glue, notch filter, and "phase" plug modification design to my Web site.

As long as I did not mess something up while making the changes to the Web site, this url should get you to the P17 mod.

http://madspeaker.com/Projects/VifaP17/P17mod.htm

A transiently aligned two-way using the P17 and a TB tweeter is coming.

A pair of the speakers have been in use for about 8 months now. I would say the modifications and tweeter offset design for transient coherence are well worth the effort.

Now, the long story. I offered this mod to PE's Project Showcase around November 2004. Although I reposted it twice to cover e-mail problems, there was never any reply. I decided I sat on the modification long enough and so have added it to my own site.

Good designing and good building,

Mark
 
Mark, I have speakers with the Vifa P17 and D25AG in an MTM and I'm keen to try the mod. The phase plugs look great! I think I'd like to put the glue on the rear.

Could you explain a bit more about the nature of the problem the glue addresses?

I'd also like to hear your comments on the phase plug and what it does. My understanding is that it reduces power compression under the dustcap, and improves thermal power handling via heatsinking. What about the impact on bass response and efficiency due to making the driver lighter and reducing SD slightly? I would have thought that a phase plug alone would make the driver lighter and actually mess with the smoothness of the driver in the top end of its passband. This seems to be the case in the Peerless HDS drivers which have a phase plug, in comparison to the shielded versions which do not.
 
The upper range performance of the stock P17, while nicely controlled, is complex. Despite how well controlled they are by the high mass of the mineral doped cone, there are several cone breakup problems plus the vibration modes of the dust cap.

Removing the dust cap extends HF just a little and simplifies the vibration mode complexity. Getting rid of the dust cap gives a more shallow slope to the hf cut-off. This allows adding a tweeter with no additional low pass filter components. The glue applied to the cone further reduces the vibration modes of the cone. You can see the impact of this in the decay response of the stock compared to the modified driver.

If you work with the stock driver, you probably have seen how the hf response resists attempts to roll it off with a low pass filter. If you add a typical filter to this driver, the performance will not change in the way predicted. Much of this problem is caused by the vibration modes of the dust cap.

Otherwise, there is almost no change in LF performance or in sensitivity by replacing the dust cap with a plug.

I hope that this helps,

Mark
 
Mark, you've inspired me! I have a big chunk of copper in the garage and access to a metal lathe, and even if I don't notice an audible improvement, I'm sold on the idea even just for looks! Heck, if I sell them to finance my next project, they will look a lot more expensive! One thing holding me back is being able to measure before and after. If I just go ahead and do it, I won't be able to measure (another thing on my to do list is a mic preamp).

Mike,
which amp do you mean? I have a NAD power amp I haven't gotten back from the repair man yet, and I have a chip amp that works nicely apart from the hum (grrrrrr) - I use it for my tweeter but unfortunately it sends a hum through the whole system! :xeye: :smash:

It's in an ugly box, but I'm thinking of making a decent looking box for it. But ahhhhhhh, so many projects I want to do - fix the amp hum, fix 2nd sub processor to get subs in stereo, box for sub processor, midbass horn sub, vented LFE sub boxes, try OB mains with waveguide for tweeter, build a "hush box" for my PA sub amp to quiet fans, hifi rack, decent diy cables and RCA and speaker walls plates ......... then when all that's done, figure out a way to turn it all on and off safely (no thumps) with one switch!
 
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