Waveguide for XT25

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And is this also saying that if the speaker does not have a bullet there is no point in fitting a waveguide?

I supplied the links to Dave's web site. If you visit the site, he has various wave guides for many tweeters other than the XT25 that dont have the phase plug. If you look at the test results I imagine it would make clear everything that is giving rise to your questions. Many tweeters are used with wave guides. As far as dave;s product's you're limited to what he sells. Many wave guides have been used with great success with non-phase plug tweeters. I personally like the XT25/60 and think any argument against it is negated if used with a wave guide so for me, the tweeter search ends with the XT25 and Dave's 8x5 WG.
 
An 8uf cap will cut you 6db at 2500hz. You would be down about 22db by the res freq which really cleans up the lower end. You may have a slight dip at 1900 to 2200 but thats a minor 1-2db vs the suppression of higher order distortion from 4-10K and F2 and F3 at the cross over range. Your power handing also climbs a lot.

If you have EQ you can fix any irregularities. I think you said you had a minidsp.

I wish you lived closer. I would have loved to see/hear your speaker. It looks like a winning combo.
 
Many thanks for the info.
I'm looking at integrating my Symasym amps into the rear of the cabinets. I built them initially to fit into the stands of the Centaurs, but after extensive listening, decided there was no significant improvement,if any, so put the stock Apogee crossovers back. Though I must say I prefer the Symasyms actively driving my other speakers.
 
Today, I ran the speakers biamped with my Symasyms and a buffer preamp. I readjusted the minidsp and set the high and low crossover slopes to 12db LR. Now this is a WOW, only because I have just heard the most convincing piano recording (Horowitz in Moscow) as never before.
I haven't tried the cap yet, but I did find a couple of spare 6.8uf and 8.2uf caps to try when I can stop listening to these.
Peter
 
The cap removes a layer of grain you just dont realize is there until its cleaned up.

I agree. Piano, female vocals, and most of all horns sound amazing. I used to like the bass in my system the most. Four 15's and 8000watts make for the most detailed clean notes but now the midrange is what I love the most in my system. I went back to all my CDs just rediscovering what I didnt know was in the recording. These speakers are some of the cheapest I've built but give me the most satifaction which is about all money can do for you.

My next set of wave guides just shipped from Dave. I want to build a small bedroom system with them.
 
What drivers are you using?
I built these cabinets to test three configurations.
1. 2.5 towers with Xt25 and Peerless woofers.
2. Tang band full range with 5-1/4" mass loaded TL sub.
3. These WG 2 ways.
All were excellent, but the WG version is exceptional. I really appreciate all the comments in this thread that helped me along.
Peter
 
Doesn't the crossover slope in MiniDSP negate the need to put a cap on the tweeter?

Simply said - no, not just with xo slopes! minidsp has fixed xo slopes like LR12, LR24 etc. The 6dB/octave correction must be done with parametric EQ by adjusting Fs, gain and Q to simulate a cap. This should be verified with measurements to get perfect xo match.

A real capasitor works also for protection of the tweeter for accidental harsh burrs and chunks caused by the excited diyer doing misconnections with his amps and minidsp!

"Been there, done that"
Juhazi
 
Ahhh.... got it. Thank you. I am just starting to read up on the possibility of a DIY digital active studio monitor and was under the impression that a digital crossover could essentially replace any slope/eq/voicing/contour circuit that one would do passively, but I guess that is not yet the case.
 
Doesn't the crossover slope in MiniDSP negate the need to put a cap on the tweeter?

The cap is starting at the top of where the wave guide is lifting the low end. Thats not at your cross over freq but rather up near 5000 to 6000hz. The cap gets you back to flat around 1700 to 2000 and then the mini DSP is doing the cross.

Here you see the wave guide starts the lift at around 6000. The cap gets it back to flat. You arent using the minidsp from 6000,; its not the cross over frequency. You also need a cap for DC protection.

This is the Seas 27-TDFC bare response
Seas_27TDFC-FR_zps136b33f2.gif


This is the lift with a small 6" wave guide (I used a 8" wide for the XT25 = more low end lift)
hornconversion-horn-fr_zps95508c32.gif
 
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Greggo, minidsp is not just a digital xo device. It gives many possibilites to do frequency response corrections in many ways. Each output channel can hava 5 different eq settings with different parameters. Also delay and polarity inverting is possible. These and xo are adjusted indpendently. In addition each input channel can have 5 eq settings too, mainly for room correction use.

However, it can't give protection to the tweeter if the low/high level signal (hum, noise, click) comes after minidsp (it's output - power amp-speaker lines being mishandled, and that happens easily!)
 
As you already said, the cap is protecting the direct interface to an amp. Little caps starting at 6000hz are far cheaper than bigger caps starting down lower in freq, so why not just use the smaller cap?

Keep in mind for those using active crosses that every EQ adjustment uses up memory and lowers resolution such as on the DCX2496.

The tweeter is at an acoustic 2nd order with just a cap and it is aligned with the midbass because the wave guide moves it deeper into the cabinet. This eliminates the need to slant the baffle for 2nd order crosses.
 
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Instead of installing a cap, and after taking another look at the super-simple crossover in the Zaph Audio waveguide speaker, I dialed in similar crossover points into the minidsp.
I wound up with 10kHz first order on the tweeter and 1400Hz first order on the woofer. I added a -8db low shelf at 1kHz to the tweeter to reduce output at the resonance frequency further. Woofer is dialed down 4db, and a little EQ introduced to reduce room anomalies. Very smooth yet dynamic. I'll continue to evaluate and play.
Peter
 
Why would you use such a limited slope if you are active? Using the shelf from 10K and then a 4th order electrical at 1900 would increase power handling and lower distortion far more than the passive values Zaph used to keep it simple. What Zaph built wasn't optimum. Its was value and simplicity motivated. Neither is a constraint in active systems.
 
Waveguide fun

Spinmonster...
I have been playing with the waveguides and built a TMM with 6.6" Nomex woofers, since the Vifa 8" woofers are now back in my heavily modified ported Centaurs. The Apogees are firmly entrenched in my main music system and are now a huge improvement over the originals. However, the continuing lure of DIY is hard to resist - here is a picture of the TMM set up. I took your advice and wound up with a 8.2uf cap on the tweeter and added a 4.7ohm resistor to bring the level down. The woofers have a .68mH inductance on both, and a 2.9mH on the lower woofer. The result is not the smoothest speaker I have heard, but certainly the most lively. Reminds me of my Royd Heralds but with more weight and better dispersion. Should be a good match for my F5 clone - not tried yet.

Peter
PS - the cat is quite taken with the Centaurs, too
 

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It's been a very busy diy winter for me. I picked up a pair of Infinity 8 Kappas at the local thrift shop for $50 and found some decent 11 ply oak faced plywood at Lowes.
I knocked together a couple of 1 cu ft cabinets from the ply and mounted the waveguides and Peerless 6.5" Nomex mid/woofers in an mtm configuration. Using the minidsp and a 8.2mfd cap on the tweeter, these provide a stunning clarity to voice, piano guitar etc. My "sweet spot" Apogees have been in the closet for the past three months.
 

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