[FredT300B]

Here's a new project I completed this morning using an OB Dayton Audio PS220-8 with an H-Frame Eminence Alpha 15. A DEQX processor is used as the crossover (150hz) and for equalization. My first impression is the subwoofers have a rich "vintage" quality, full and powerful but not especially well controlled. The Dayton point source drivers sound surprisingly clean, with a broad 6dB peak around 3.5khz that sounds bright on axis, but not so off axis. Just to get things going I added some equalization to minimize the 3.5khz peak and some other smaller anomalies, and I'm listening with the speakers toed-in, facing the listening position. For now I'm driving them with a pair of Emotiva UPA-2 stereo amps.

[gab]

Here's a new project I completed this morning using an OB Dayton Audio PS220-8 with an H-Frame Eminence Alpha 15. A DEQX processor is used as the crossover (150hz) and for equalization. My first impression is the subwoofers have a rich "vintage" quality, full and powerful but not especially well controlled. The Dayton point source drivers sound surprisingly clean, with a broad 6dB peak around 3.5khz that sounds bright on axis, but not so off axis. Just to get things going I added some equalization to minimize the 3.5khz peak and some other smaller anomalies, and I'm listening with the speakers toed-in, facing the listening position. For now I'm driving them with a pair of Emotiva UPA-2 stereo amps.

Fred - will you be bringing these to LSAF this year?

[Ric Schultz]

You need to do three things to the Eminence woofers to get good sound:

1. You MUST burn them in at high volume for hundreds of hours......you can use a 40hz tone while you are gone.  They are very stiff at first and sound really sluggish.  They will start to "snap" after several hundred hours of hard movement. 

2. You MUST damp the ringing speaker frame.  Use EARSD40AL on all the struts.  Much tighter and more musical sound.

3.  You MUST damp the magnet from any movement.  Even though you damp the struts the magnet will still have microvibrations.  You want to brace the magnet to the sides of the H-Frame.   

Please check out my gallery and in my open baffle folder you will see a pic of an Eminence driver in an H-frame with the EAR mounted and a magnet mounting system.  I epoxy 13 ply piece (not blocking hole in driver) to back of magnet and then bolt another 13 ply piece to it that is mounted to H-frame.  The ply that is attached to the H-frame also has a notch cut out so the air from the vent in the magnet can excape.

Your bass will be much better after the three above.  An Ncore amp will tighten it up more.  Of course, you must have great spikes and solid mounting to floor or else you will hear mud.  You might want to add more mass/weight to the top of the H-frame to create a more solid mounted mass.  The extra weight will also damp the top of the H-frame from ringing.  You can double or triple up the bottom of the H-frame as well and use green glue between the layers......so many possibilites for better sound.  Have fun.

Also, I hope you are doing time alignment with your deqx.  The mid/tweet is way forward of the woofer so you need to delay the mid/tweet quite a bit to get them to align for best sound.  You can hear even 1mm of change.  You are inches off!

Also, also......since you have such a wide baffle it is going to sound much better if you felt the whole thing (If it does not move...then cover it...is my motto).  This will make the baffle disappear....so to speak.  Remember to felt the speaker sides that stick out beyond the baffle.....they are seriously reflecting sound.

[jparkhur]

Does the wide baffle effect the sound much?  I have seen the other versions of the oB dayton and noticed that increasing the baffle beyond 10 inches increases some of the driver issues-others are just fine.

JP

[FredT300B]

You need to do three things to the Eminence woofers to get good sound...

Ric, thanks for the suggestions.

[FredT300B]

Does the wide baffle effect the sound much?
JP

I don't know. I've never used this driver in any baffle width, so I have no basis for comparison. Baffle step shouldn't be an issue since I'm using active equalization. I did some preliminary frequency response measurements without and with equalization. The files are bmp's, which I can't post in the gallery, but they do appear in this thread: http://audioroundtable.com/forum/index.php?t=msg&th=18144&start=0&

[FredT300B]

Gab, if I like the sound when I'm done tweaking, they will be coming to the LSAF with me.

[tryman]

Does the wide baffle effect the sound much?  I have seen the other versions of the oB dayton and noticed that increasing the baffle beyond 10 inches increases some of the driver issues-others are just fine.

JP

my experience with EV12trxb (12inch) with 65cm wide  baffle compare to  40cm. the  40 cm make smooth curve 
With 65 cm. I got peak at 6k frequency. hope this help.

[FullRangeMan]

This Yamamoto test may help:
http://www.6moons.com/audioreviews/yamamoto9/speaker.html

[underdawg]

interesting bracing of driver

[-Richard-]

Hi Fred ~

I have the same drivers in a modest size OB... I used Erling's suggestions for 'taming' the 8" Dayton Neo driver using a passive EQ arrangement (except I have not yet implemented his further addition which he was kind to share with me/us... I have been quite busy for almost a year).

What "active" EQ are you using?

I toy with the idea of purchasing a (relatively) inexpensive Behringer EQ (I forgot which one our Augiocircle members recommend) but I have not yet got around to that either. It seems the Behringer works in-between the preamp and amp... now I have that setup but before I used an integrated amp.

Very substantial looking design... you are fortunate to have the room necessary for them. I can only imagine the enveloping sound you must be getting. What kind of amplification are you using?

With Warmest Regards ~ Richard / Ojai, California

[galyons]

You need to do three things to the Eminence woofers to get good sound:
...
2. You MUST damp the ringing speaker frame.  Use EARSD40AL on all the struts.  Much tighter and more musical sound

I am working on an OB with the Eminence Alpha 15.  I appreciate your thoughts on getting them to sound better.  I looked at the pic in your gallery.  I plan to brace the magnet as described. Can you tell what EARSD40AL is?  Tried googling to no avail! (other than right back to your post here!)

Cheers,
Geary

[SAC]

That EARS stuff is the stick on dampening sheets, commonly used on car doors to reduce noise/vibration.  I use it on my alpha 15a drivers.  My UK stuff has a foil outer, then a soft black layer, than a sticky surface for adhesion.

[FredT300B]

Hi Fred ~

What "active" EQ are you using?

I was using the DEQX HDP Express as an active crossover and for equalization, but I quickly realized, except for the Dayton driver's peak that's centered around 3.6khz, this speaker doesn't sound too bad with no equalization. So I decided to see what I could do using only some passive equalization, and the result sounds very good to my ears. The equalization is done by a parallel notch filter consisting of a 6.8uF cap, a 0.2mH inductor, and a 12.5 ohm resistor, all wired in parallel into the driver's positive lead. This reduces to peak to almost flat. For the subwoofers I'm using a couple of 100 watt subwoofer plate amps. I've found the plate amps must be set to the highest crossover point, which is 180hz for these, to eliminate a broad null below about 200hz. Because of this high crossover point I recommend using a dedicated sub amp for each channel. With the notch filter and sub amps the frequency response still has some significant peaks and nulls. The in-room response is flat within +/-5dB from about 37hz to 20khz.

Even with the notch filter in the circuit, the Dayton drivers still retain most of their 95.6dB sensitivity, and are easily driven by my four watt OddWatt amp.

Without the active crossover and dsp equalization this becomes a more affordable project, and because of the simplicity of the H-frame, full range driver baffle and side panels, it's also one that's easily built by a beginner. I'll be taking these speakers to the Lone Star Audio Fest in May so others will be able to hear them and comment on their performance.

[galyons]

That EARS stuff is the stick on dampening sheets, commonly used on car doors to reduce noise/vibration.  I use it on my alpha 15a drivers.  My UK stuff has a foil outer, then a soft black layer, than a sticky surface for adhesion.

Perfect!  Thanks, that will be easy....
Cheers,
Geary

[Ric Schultz]

EARSD40AL is a constrained layer damping material made by EAR.  SD is the type.....40 indicates it is .040 thick and AL is the version with alluminum layer on top.  They make a EARSD40 but it sounds no way as good.  The only place that I know that stocks it is Michael Percy Audio (page 19 in his catalog).  Not cheap but the best sounding constrained layer material I know of.  First listen to the woofer stock....then put the EAR stuff on.....then magnet damp/mount.....you will hear a substantial improvement with each mod.  Of course, you want the baffle its mounted on to be rigid and braced.

[FredT300B]

... I used Erling's suggestions for 'taming' the 8" Dayton Neo driver using a passive EQ arrangement ...
With Warmest Regards ~ Richard / Ojai, California

Can you give me a link to this? Thanks.

[galyons]

EARSD40AL is a constrained layer damping material made by EAR... The only place that I know that stocks it is Michael Percy Audio (page 19 in his catalog).  Not cheap ....

Thanks Ric,
Should have known it would be Percy!  Michael and I are on the outs!  It just got so, based on the money I send him, that I could claim him on my taxes as a dependent.  Then, showing an utter lack of consideration, he ups and moves to Maine!!! 

I will do as you described.  Currently have run wife out of house playing the bass 1/3 octave signals off the Stereophile test disc VERY LOUDLY!

Cheers,
Geary

[FredT300B]

The Audio Circle gallery doesn't accommodate bmp files, so you'll have to go here and scroll down to messages #75587 and 75588, both dated 2/21, to see the measured frequency response, first without the notch filter and then with it. I realize many full range single driver speaker fans prefer to listen with no passive parts in the signal path, but without the filter these speakers are in-your-face bright, and with the filter they sound much more like other uncolored high end speakers I've become accustomed to hearing. I will be taking these to the Lone Star Audio Fest with the notch filters installed.

http://audioroundtable.com/forum/index.php?t=msg&th=18144&start=0&

[FredT300B]

Finally got them painted.