[Angaria]

After some experiments with a pyle ppa15, I've concluded I can't match it up to my rd75's and still get decent sounding male vocals.  So, I'm in the market for a 75" high x2 line of midbass woofers that can go as high as 600Hz and will go low enough to mate with a dopole sub.  I'd really like the design to be all open baffle (even tweeters are neo3's without backcups).  Digital crossover and EQ are via Behringer.

I'm looking for moderately high qts options and my first choices are the RS225 or DA175 (actually qts is fairly low here, which has me worried).  The 20 of the DA's are certainly preferable price-wise.  Any other options that have worked well OB?  Thanks.

[Rick Craig]

After some experiments with a pyle ppa15, I've concluded I can't match it up to my rd75's and still get decent sounding male vocals.  So, I'm in the market for a 75" high x2 line of midbass woofers that can go as high as 600Hz and will go low enough to mate with a dopole sub.  I'd really like the design to be all open baffle (even tweeters are neo3's without backcups).  Digital crossover and EQ are via Behringer.

I'm looking for moderately high qts options and my first choices are the RS225 or DA175 (actually qts is fairly low here, which has me worried).  The 20 of the DA's are certainly preferable price-wise.  Any other options that have worked well OB?  Thanks.

How low do you want the woofers to go? Crossover point? Baffle width?

[Angaria]

Hi Rick, 

I'm still planning on having at least 4 15" woofers in an adjacent dipole bass setup, so the midbasses only need to get down to ~60-80Hz. 

Baffle width could be 3.5-4'. 

The rd75 sounds good down to 600Hz and works down to 150Hz, so I thought a 600Hz crossover point would be good.  I can control the point and slope with the deq2496.  Thanks!

[Danny Richie]

Hey Angaria,

I have already been working on an open baffle line source, and hope to have something available in the first quarter of next year.

For one I can't recommend strongly enough that you avoid those cheap metal cone drivers. IMHO they are very veiled and lifeless lacking any resemblance of realism. The Qts on those woofers is too low too.

I have some custom woofers being built just for this application. In fact I just took delivery of 30 sample units for testing.

These are 6.5" woofers with the same polymer frame as the woofers being used in the LS-6 and LS-9. The cropped frame allows easy stacking. They also use a paper cone. The low end will be very well controlled with the very linear XBL^ motor and 7.8mm of X-max each way. The response is smooth as glass and has little to no break up too.

Here are the parameters if you want to model them.

 "DCR mode: Fixed (5.42 ohms)"
 "Area (Sd): 137.07 sq cm"
    55.261 "Fs Hz"
     5.420 "Re Ohms"
    35.806 "Res Ohms"
     5.600 "Qms "
     0.848 "Qes "
     0.736 "Qts "
     0.323 "L1 mH"
     0.677 "L2 mH"
    18.881 "Vas(Sd) liters"
    11.593 "Mms(Sd) grams"
   715.509 "Cms(Sd) æM/Newton"
     5.073 "Bl(Sd) Tesla-M"
    89.270 "SPLref(Sd) dB[8 ohms]"

It will be some time though before I have stock available for sale.

Obviously I will be using some new custom built planar magnetics that are also open backed.

I also have 12" subs in the works specifically for the open baffle application and it involves some new patented technology that will put them well beyond any other open baffle sub. I'd fill you in on the details if you like, but not here.

I can't wait to get further along on it, fun, fun.

[Rick Craig]

Hi Rick, 

I'm still planning on having at least 4 15" woofers in an adjacent dipole bass setup, so the midbasses only need to get down to ~60-80Hz. 

Baffle width could be 3.5-4'. 

The rd75 sounds good down to 600Hz and works down to 150Hz, so I thought a 600Hz crossover point would be good.  I can control the point and slope with the deq2496.  Thanks!

Either Dayton driver will work well but with the RS225 you do get a lower distortion motor. Since you are running active either driver's Qts is fine. Back in the old days Bob Carver used high-Q drivers to extend the bass response; however, the definition and detail of high-Q drivers isn't very good because of the weak motor. The suspension also becomes a factor and your amp doesn't have as much control over the woofer.  That's why Linkwitz and others are using active EQ with lower-Q drivers. That approach is much better and audibly superior.

[Danny Richie]

however, the definition and detail of high-Q drivers isn't very good because of the weak motor.

This is completely false. Just because the Qts goes up does not mean the motor gets weaker. In fact the motor structure on the above mentioned woofer is the same motor structure used on the current LS series woofers.

I really don't agree with the rest of what you said either.

BTW, some of the best sounding mid-range I have ever heard was using a high Qts driver.

[Rick Craig]

however, the definition and detail of high-Q drivers isn't very good because of the weak motor.

This is completely false. Just because the Qts goes up does not mean the motor gets weaker. In fact the motor structure on the above mentioned woofer is the same motor structure used on the current LS series woofers.

I really don't agree with the rest of what you said either.

BTW, some of the best sounding mid-range I have ever heard was using a high Qts driver.

High Qes and Qts numbers often go hand-in-hand. A high Qes means low motor strength - a small magnet, low strength magnet, motor that has a magnetic field further away from the voice coil, or any combination of these factors.

[cixelsid]

The RD-75 is an excellent midrange and should be paired with something better than the DA175.

The RS225 is a very good driver, the low Qts means it's slightly overdamped, in reality that's not a problem

The RD-75 aren't that efficient so you could use the RS-180's. Those have a nice Qts 0.48 and the unshielded versions are reasonably priced in quantity.

[Angaria]

While I have the line array experts on hand - I also have 15 neo3 tweeters a side ~ 45" of treble.  Is there a point in expanding the tweeter line that handles 4KHz+ or should I should I dump my money into the midbasses?  (grad student here)

[Danny Richie]

15 Neo 3's are easily capable of handling 1,200Hz to 40kHz. Been there done that got a Golden Ear award. What more could you ask for?

[cixelsid]

While I have the line array experts on hand - I also have 15 neo3 tweeters a side ~ 45" of treble.  Is there a point in expanding the tweeter line that handles 4KHz+ or should I should I dump my money into the midbasses?  (grad student here)

The RD-75 tend to beam at higher frequencies and have the cavity resonance around 5kHz. This means having the neo 3s running around 4kHz or so is a fine idea. There's not need to run them much lower, but you can explore various crossover topologies and frequencies using your DCX2496.

The tweeter line only needs to be as tall as you want the vertical window. There's little gained by having the line as long as your RD-75.

[Danny Richie]

Having compared the RD series drivers to a line of Neo's there are a lot of good reasons to go with the line of Neo's.

For one, they sound a lot better. Then there is the much higher sensitivity and power handling. The Neo's also don't have any resonance problems, and they extend much higher on the top end.

The Neo's won't play quite as low, but pushing the RD driver that low doesn't sound realistic either. While it will play low, it won't do so with much output capability. It just has no ability to move any air in the lower ranges. I'd use a dynamic driver below 800Hz.

For example, the hit of a snare drum. Through the RD driver crossed over real low, it sounds like a snare drum, but doesn't have the feel of a snare drum. There is no sense of the impact. It is like listening to it on head phones.

Crossing in the 300Hz range puts the crossover point in the heart of the mid range and is not a good place to be splitting vocals into dissimilar drivers.

As far as making the line of Neo's longer, the more you use the higher the sensitivity (depending on grouping numbers), the higher the power handling, and the less load there is on each driver (lower distortion). Plus, the more of them you use the more gain you get in the lower region and the lower you can cross them. I have used 6, 12, 18, 20, and 21 units in a line. The larger numbers sounded better.

[Rick Craig]

While I have the line array experts on hand - I also have 15 neo3 tweeters a side ~ 45" of treble.  Is there a point in expanding the tweeter line that handles 4KHz+ or should I should I dump my money into the midbasses?  (grad student here)

45" is fine for typical listening distances of 7-15 ft. I'm not that familiar with the Behringer but you should have enough control over the gain to match the Neo3 and and RD75 levels. Once you set up the lines you should measure the response off-axis to both the left and right of the speaker. That will help you determine the crossover point.

[Angaria]

Thanks guys.

The following NHT surplus driver seems like it could work.  Reviews from its native VR3 high-end HT speaker are favorable.


6.5"   Peerless   
Basket: Stamped Steel   
Cone: Laminated poly   
Re:   8.63   
Fs:   39.4   
Qms:  2.588   
Qes:  0.633   
Qts:  0.509   
Vas:  24.29   
Cms:  0.000796   
Mms:  20.46   
Bl:   8.31   
SPL:  85.54   
Zmax: 43.9   
Sd:   .01474   
xmax(mm):  5.5   
Hg(mm):    6.0   
Hvc(mm):    17.0   
Coil layers:2   
Coil Diameter(mm): 32   
weight: 4.6lbs
$14

Source:
Specs:
http://home.comcast.net/~jhidley/NHT_Drivers-2.xls
Description:
http://home.comcast.net/~jhidley/

[Danny Richie]

The price is certainly right. The numbers don't look bad either. Let us know how it turns out for you if you go that route.

[Rick Craig]

Thanks guys.

The following NHT surplus driver seems like it could work.  Reviews from its native VR3 high-end HT speaker are favorable.


6.5"   Peerless   
Basket: Stamped Steel   
Cone: Laminated poly   
Re:   8.63   
Fs:   39.4   
Qms:  2.588   
Qes:  0.633   
Qts:  0.509   
Vas:  24.29   
Cms:  0.000796   
Mms:  20.46   
Bl:   8.31   
SPL:  85.54   
Zmax: 43.9   
Sd:   .01474   
xmax(mm):  5.5   
Hg(mm):    6.0   
Hvc(mm):    17.0   
Coil layers:2   
Coil Diameter(mm): 32   
weight: 4.6lbs
$14

Source:
Specs:
http://home.comcast.net/~jhidley/NHT_Drivers-2.xls
Description:
http://home.comcast.net/~jhidley/

That woofer should be fine for your application. Wiith the RD-75 having low sensitivity a midbass with mid 80's sensitivity is a good match. One thing you might want to check is the frame because a stamped frame typically has wide spokes that can interfere with the rear wave.

[Angaria]

Glad I've found something that could work.

Rick - on your point about not blocking the back wave, it does look kind of congested there.  I could pry off the sheilding, but I don't know how much of a difference that will make.

[jeffreybehr]

http://www.audiocircle.com/index.php?topic=32172.0

The Sonic Craft JG65 6-1/2" B/MR drivers are only $10 each in 24s and they sound GREAT.  Properly baffled and filtered they're good for about 50Hz - 2.5KHz.

Then it can be a 3-way system with 1 driver/set of drivers carrying 6/10s of the music.

I'll be rebuilding my system with 10 per channel and one point-source ribbon tweeter.

[zobsky]

http://www.audiocircle.com/index.php?topic=32172.0

The Sonic Craft JG65 6-1/2" B/MR drivers are only $10 each in 24s and they sound GREAT.  Properly baffled and filtered they're good for about 50Hz - 2.5KHz.

Then it can be a 3-way system with 1 driver/set of drivers carrying 6/10s of the music.

I'll be rebuilding my system with 10 per channel and one point-source ribbon tweeter.

Curious, .. why are you abandoning your planar tweeter solution?

Thanks

[Angaria]

wow, even google hasn't heard of the JG65.  Is sonic craft still selling these?  If not, $10... it's just too cruel.