# Another set of monitors!



## fusseli (May 1, 2007)

I am going to be making two sets of smallish monitors for some friends. The design is inspired by my previous "HT 1.0" build with the TangBand W5-704D woofer. It works well in smaller boxes, it's forgiving roll-off is easy to work with, and it has good looks. This time I'm going with the Vifa XT25TG30 tweet for a little more gusto, and going with larger cabinets for deeper extension. Also only going with about 3.5dB of BSC this time.

Here's the first hack at an Xover using Zaph's data, my drivers are in the mail. Upon their arrival I will measure true .zma's with my WT3 and make tweeks if necessary. Behold, "HT 2.0"!


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## robbo266317 (Sep 22, 2008)

That looks good. It should be a worthwhile project/gift which I am sure they will cherish.


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## hjones4841 (Jan 21, 2009)

Giving audio gear as wedding presents, what a great idea! Starting them off right


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## Jstslamd (Nov 30, 2010)

You've got my attention!!


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## ALMFamily (Oct 19, 2011)

Very nice gift - looking forward to the build!


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## fusseli (May 1, 2007)

With drivers in-hand, tweaked up the Xover after taking some measurements. Not too much changed. Per the measured T/S params, I changed box tuning a bit. I also added more BSC.


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## Brewski (Jan 8, 2010)

It looks really promising in PCD they should make a pretty nice speaker for them.

Take it easy
Jay


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## fusseli (May 1, 2007)

More progress, just missing some cabinets. May rotate one of the coils on their side when I put them in if they end up being in very close proximity.


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## Brewski (Jan 8, 2010)

Is there enough room to lay the P-cores on there sides and zip tie them to the crossover board at each end of the P-core? I've seen a couple case of P-cores cracking during shipping and tend to think with them tipped there would be less stress on the "bobbin" if the speakers ended up shifting quickly. (car ride, opps, etc)

Take it esy
Jay


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## fusseli (May 1, 2007)

It's almost a year later and I'm just now getting around to finishing up these speakers. Per the end user request, I reduced cabinet size as much as possible on one set (to .25cuft tuned to 51Hz), so I re-modeled all of my impedance files after WT3 measurements. The baffle is tight but it should work out okay. This resulted in some tweaks to the tweeter HPF since at the same time I noticed a mistake in the .zma file I generated for the 704Ds in Response Modeler, which was not having the rising impedance of the woofer lined up correctly.  

Final acoustic crossover is about a 2.4kHz 4th-order Linkwitz Reilly. Working on cabinets and making the crossover changes now in the coming week :bigsmile: Compared to the "HT 1.0" build, these will have a 2" port tuned higher to 59Hz, which is the longest possible with the orientation constraint in the cabinet. This actually slightly lowers the f3 and will reduce any port noise possibility. Intention being to have them used with a sub, crossed at 60-70Hz.


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## fusseli (May 1, 2007)

Here are the PCD shots using traced and processed FR data and my own measured impedance data, looks +/-1dB from about 90Hz-16kHz and +/-3 for 70-20kHz+. I included 4dB of BSC into the crossover. There is a large bump in impedance phase at 2k but I'm not too worried about it. The rise at 20kHz is a 2dB bump in the XT25's normal FR, also not worried about. To "deal" with it I plan on using an ordinary wire round resistor for the 2.2 Ohm one out front of the HP section, hoping that the tiny bit of inherent inductance will trim it down (about .03mH would do it).


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## fusseli (May 1, 2007)

Almost finished with the first set. Construction is essentially complete and I'm just waiting for paint to dry on the baffles. Decided they were too scratched up during cutting and needed to be painted. Overall the finish of the PE cabinets is very nice, and well worth the money in my opinion. Days of work and headache is saved with these things. I routed a minor round over on the back of the woofers to hopefully reduce any diffraction in the midrange. This was the first time I've done routing with a router that has dust collection, and boy is that an awesome feature. Hardly a shred of sawdust in my garage afterwards :bigsmile: The woofer section of the crossover is glued down into the rear of the box, the heavy p-core inductor is a concern to me. The tweeter sections are zip-tied to the bracing with some foam cushion. I added a few ounces of Acousta-stuf to the lower area of the box and formed a sort of pillow to sit behind the woofers, for controlling internal reflections in the midrange. I've seen this done a few ways so I've made up my own solution. I am unsure of how this works versus using solid acoustic foam.

I verified the crossover impedances with the WT3 and it looks to be a close match to the PCD model. I started a thread in the REW forum with some near field measurements, results are looking great. There is a slight drop in SPL in the tweeter section which I have adjusted for by changing the parallel 4 ohm resistor up to 8 ohms, adding about a 2dB boost. This seemed to agree with initial listening impressions that they sound great and clear, but a little dark. I will post final measurements once I'm done tweaking. Interestingly, my UMM-6 does not measure the 20kHz hump that is in the published FR of the XT25TG tweeter. Perhaps it isn't there, or is less pronounced.


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## fusseli (May 1, 2007)

Well, they are finished. I ended up swapping out the 4 ohm tweeter attenuator resistor to boost up the high end. They sounded a bit dark at first and sure enough, REW measurements show about a 2dB drop after transitioning to the tweeter. A simple swap to an 8 ohm resistor and it's nearly a +/-1.5dB speaker :sn: I re-painted the baffle with a dark walnut brown instead of the original satin black. I think it's a better compliment to the veneer when the grills are off. The speaker look and sound awesome. Pictures and plots don't do them justice!


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## lfergus08 (Jan 25, 2012)

Finally got the new speakers up and running in the new place. I will post pics of their final resting place. Needless to say these are the best wedding presents ever! (even a year and a half late ) Spent the majority of the day listening to new and old music.


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