[Nate Hansen]

I posted this over at DIYA but I figured I'd drop it here as well.

I'm starting a new project, so I figured I'd document my current setup. I haven't done any work on these in over a month, and the data is kinda scattered on my computer but I think I pulled together the relevant info.

These are active 4-way dipoles. I call them "Dipole Disorders" because of the impact my audio addiction has had on my life the last couple years . It's been fun though. The drivers are: Neo3, Neo8, Vifa M21, and Eminence Delta LFA 15". I chose the B&Gs due to their equal front-back radiation and small size format. The Vifa's were stand-ins until I found something better........more on those later. The Emi's were a decent price and had the parameters I was looking for when I put the u-frames together a year ago. The upper 3-ways are hung by wire from a frame attached to the u-frame. The wire hangs on grommets slipped over the bolts in the top of the frame. I can't feel any vibration transfer in the upper 3-way drivers from the woofer. Good enough for me. The u-frames are made out of .5" chipboard, just meant to be prototypes. I never got around to making nice ones. The 15s are magnet mounted as well as mounted to the baffle.





Crossovers at 250, 900, and 4000. I've played with different xo points but this is where I've settled. I wanted to get the widest bandwidth I could out of the Neo8s without disrupting the polar response too much. The filters themselves are a sort of elliptic-notch filter, with a LR4 roll-off then transitioning to an 8th order in the stop band. Tried various topologies here as well and this is what I'm happy with. Here's the individual eq'd driver responses on axis from about 60". The measurements were made with ARTA, but I haven't licensed it yet so I exported them to REW. Gating if I remember correctly was 3.5ms.



No eq driver measurements, starting with the Neo3:



Neo8:



Vifa M21:



Delta 15 in u-frame:



I suppose I should state some design criteria, so this all makes a little sense . I've been playing with dipoles for a couple years, starting with an 8" FR over a cheap 15" woofer. Intrigued, I decided to go all out on an active 4-way system. My main goal is constant directivity through as wide a bandwidth I can get. I live in an apartment so high SPLs are not required, and the woofer's eq'd response down to 40hz is plenty. With the decision made to get CD, naked drivers seemed an elegant solution. Plus, I don't have a garage and a lot of tools so ease of construction is a bonus. Due to the unbaffled response of the drivers active xo/eq was a no brainer. I think it has its benefits as well. I decided on 4-ways because I wanted to use the Neo3s, but I don't like them below 2500hz. I wanted to cover roughly 1k-5k with one driver and this is the best I could do with my design constraints. Here's the polar response at 0,15,30,45, and 60 degrees (the green measurement in the middle is ARTA's calculated power response). I lifted the top octave on-axis to get a flat power response.



The Deltas were eq'd from about 10-12 measurements taken around the listening position. I also did a bit of selective DRC from the listening position, using the same method of 10-12 measurements around the lp. Here's the left and right averages after eq:

[Russell Dawkins]

I presume you are aware of the project by "StigErik", but in case you are not, have a look:
http://www.diyaudio.com/forums/multi-way/142015-my-open-baffle-dipole-beyma-tpl-150-a-52.html

[this_is_vv]

Whats the difference between Neo3 and Neo8....i see they look preety same till 18khz or i am not reading it right.....i just got a pair of Neo8 instead of Neo3....

can you share your experience with these drivers...

V

[Nate Hansen]

Whats the difference between Neo3 and Neo8....i see they look preety same till 18khz or i am not reading it right.....i just got a pair of Neo8 instead of Neo3....

can you share your experience with these drivers...

V

The 3 and the 8 are quite a bit different. The Neo3 is a tweeter and the Neo8 is more of a mid-tweet. The 8 has roughly 3 times the surface area of the Neo3. This is up to personal preference of course, but the Neo8 can be run down to about 500-600 hz on a baffle or in an enclosure, and the Neo 3 is only good down to about 2k. Some run it lower with steep filters, I don't like it any lower than 2.5khz. I think the Philharmonic line of speakers uses the Neo8.

It really depends on what you're doing/what your goals are if you want one or the other.....or both. The fr of each really isn't that close when you look at it closer, though they do follow the same general trend of constant directivity (when baffle-less) up to an on-axis dip dictated by the width of the driver, followed by beaming. The Neo8's on axis dip comes in at about 5k, the Neo 3 about 7k. The 8 is beaming like a laser by 10k, but the Neo3 does ok till about 15khz. My goal was constant directivity to 20k. That's not attainable with real-world drivers, but the Neo3 is much better than the 8 in the top octaves.

All that said..........I really like the Neo8's. They replaced Fountek FR88-EX's in my speakers, and the difference was like night and day. I won't go into any flowery audiophile descriptions, but I will say the search was over for an upper mid once I got the 8's.

What will you be using your Neo8's for?

[studiotech]

This has got me thinking of making some little foam pads like the Raal to increase the vertical dispersion of the Neo8 while knocking down some of the top end rise in response...

Greg

[this_is_vv]

The 3 and the 8 are quite a bit different. The Neo3 is a tweeter and the Neo8 is more of a mid-tweet. The 8 has roughly 3 times the surface area of the Neo3. This is up to personal preference of course, but the Neo8 can be run down to about 500-600 hz on a baffle or in an enclosure, and the Neo 3 is only good down to about 2k. Some run it lower with steep filters, I don't like it any lower than 2.5khz. I think the Philharmonic line of speakers uses the Neo8.

It really depends on what you're doing/what your goals are if you want one or the other.....or both. The fr of each really isn't that close when you look at it closer, though they do follow the same general trend of constant directivity (when baffle-less) up to an on-axis dip dictated by the width of the driver, followed by beaming. The Neo8's on axis dip comes in at about 5k, the Neo 3 about 7k. The 8 is beaming like a laser by 10k, but the Neo3 does ok till about 15khz. My goal was constant directivity to 20k. That's not attainable with real-world drivers, but the Neo3 is much better than the 8 in the top octaves.

All that said..........I really like the Neo8's. They replaced Fountek FR88-EX's in my speakers, and the difference was like night and day. I won't go into any flowery audiophile descriptions, but I will say the search was over for an upper mid once I got the 8's.

What will you be using your Neo8's for?

Thanks for a great response...

I am using Neo8 with a SEAS 1141 two way for Nearfield PC Speakers ...earlier i was thinking to get to Seas and Neo3 but then luckily i got a great deal on Neo8 which was hard to leave and there wasnt much online data on it...

So Nearfield PC Listening...and BTW call me still naive i am using active crossover (DCX 2496) with 5 channel gainclone 40wpc amp or 4 channel B&K 125wpc amp.....

V

[scorpion]

Hi Greg,

You have tested the Neo 8S model I think. What was the outcome, how low can you go with the S-model for instance compared to the Neo 10 ? And what is the general impression ?

Neo 8 is not really a tweeter as can be seen also in Nate's measurements of the dispersion. I think you will have a somewhat tight listening spot both horizontal and vertical in the highest frequencies.

/Erling

[studiotech]

Hi there Erling!

We got a set of Neo8s about 2 months ago.  They are fine and can play lower than the regular neo8 for sure.  We are going to be using them in a three way studio monitor from about 450-3000hz.  There is a narrow dip in response around 1.5 KHz that is not present in the regular neo8, but we judged it to sound fine anyway.  I do not have the measurements right now, but will try to take some more.  I can swap the regular and 's' version in the same box for a god comparo.

Greg

[Angaria]

Hey Nate - what are you using for an XO and amps?  Looks like a lot of headroom would be necessary to EQ that response.

[Nate Hansen]

Hey Nate - what are you using for an XO and amps?  Looks like a lot of headroom would be necessary to EQ that response.

Crossover and eq are done on my pc in J River Media Center. That goes out to an Echo AudioFire 12 which is a pro multi-channel interface.  The amps aren't anything special. Upper 3-ways are powered by 6 channels of Sure tk2050 class d and the woofers are on a big Adcom. I set the gain structure of the system at the loudest I ever listen plus a bit more for headroom. This is done with attenuators on the inputs of my amps, that way I can make use of most of the bit-depth of the interface. It was a bit of a balancing act setting it up to keep from clipping the interface outputs with all the eq I use.

[JohnR]

Nice work