|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
68.205.89.159
Has anyone here ever used dipole subwoofers ---{such as a pair of Acoustic Elegance Dipole 18 per channel}--- with OB dynamic speakers, Maggies or ESL speakers? If so how did they sound and how low did they go? I ask this because I have recently spoken with a speaker manufacturer who told me a pair of the A.E. Dipole 18 per channel is pretty darn amazing sounding! Also has anyone here ever used Nelson Pass' OB, PPSL design? If so do you believe this would be better option used as a subwoofer for 100Hz and below? Just attempting to learn about OB woofers & subs and what their strengths and weaknesses are!
TIA
I'm listening to: One More Once by Michel Camilo
Thetubeguy1954 (Tom Scata)
Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers
Follow Ups:
Hi Tom. As your question specifically relates to the ESL or Maggies, I figured it best to address this. Back in 1999/2000, Nick McKinney wrote up an article that discussed the motor design on the Lambda motor design. I have since made a revised version for our website. In this article, he states that the primary thing that differentiates ribbons, planars, and electrostatics from coil based transducers is the inductance. Inductance is virtually non-existent in those drivers because there is no coil of wire. As a result, they are extremely "fast" without any time differences introduced by inductance. It is a misconception that mass is the determining factor in "speed". Mass however changes the amplitude of the output, while inductance changes the time. In applications where you want to mate with those drivers, the ideal driver has the lowest possible inductance. All of the drivers using the Lambda motor have very low inductance due to the Full Copper Faraday Sleeve on the pole.
Nick developed the Dipole series back around that time as well. The short underhung coil had the lowest inductance of any woofers offered. They also had optimal Q for open baffles, soft suspension for good low end efficiency, inductance as low as many dome tweeters, and a very linear underhung motor with ruler flat BL out to over 15mm each way. There are no drivers anywhere at any price that offer the combination of those 4 factors.
Some drivers such as the Alpha15 have a high Q to begin with. This looks good until you realize that the Xmax is very low. In open baffles you lose a lot due to the baffle rolloff so high excursion is needed to make up for this. If you start with a high Q driver, but don't have a linear Bl curve, the Q quickly goes up. The Alpha15 with rest Qts around 1.3 quickly increases to nearly 3.0 by +/-3mm. Any accuracy achieved by having an open baffle is gone at that point. This is why Bl linearity is so important.
Determine how low and how loud you want to play. Then do a model of the baffle with Basta! and you will be able to determine how much displacement you need to achieve those goals. One Dipole15 can displace as much as 4-5 Alpha15 so if you are trying to play low, keep that in mind. The Dipole18 as mentioned is a great option. I should have some measurements from an open baffle subwoofer comparison this week. I will show a flat baffle, U, and H frame so people can see the differences. I will also show the effects of slot loading. In most cases this should be avoided. Having a woofer that is already optimized for OB/U/H baffle is preferred over trying to force a low Q driver to perform in this application by adding acoustic loading in a slot.
Hi Stryke!
It might come as a surprise to you to discover I actually know Nick McKinney! I meet Nick around 2001 through Paul Butterfield and Mike Rispoli at a Central Florida Audio Society meeting at WMFE. I've also been recently been talking with Clayton Shaw about my using a pair of your A.E. Dipole 18s mounted on a baffle, one next to each of the Spatial Audio M3 speakers as subwoofers! I'd like them to cover from 100Hz and below and look quite similar to Clayton's M3 speakers. That would be the bomb! Providing one heck of a impact below 100Hz, no?
I'm Listening to: Across The Rubicon by Silhouette
Thetubeguy1954 (Tom Scata)
Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers
Hi Tom, I definitely remember you from in the past. Were you on the basslist back in the day? I met Nick at the get together at Tom Danley's back in 1998 or 1999 I believe. Sadly Nick passed away this past year. I had taken over things for Nick after he went out of business in 2005. Would never be here doing this if I hadn't met him back then. Added a few things since that time. I think the Dipole18 with the M3 could be very cool. Clayton and I have discussed OB subwoofers as well.
Tomorrow I will be constructing a very simple H baffle and U baffle to take some measurements of. It looks like a single coil and resistor can be used to get quite flat response from below 30hz on up to 400hz or so. I will have results soon.
"Tomorrow I will be constructing a very simple H baffle and U baffle to take some measurements of. It looks like a single coil and resistor can be used to get quite flat response from below 30hz on up to 400hz or so. I will have results soon."
What kind of efficiency do expect to get with that configuration?
Dave
Hi Dave,
Open baffles in general are very inefficient due to the significant rolloff caused by the baffle. Adding the H frame or U frame does help increase the low end efficiency but can only do so much.
A single Dipole18 is about 93dB 1W. With the dual 8ohm coils in parallel for 4ohm, 2.83V input gives a max efficiency of about 96.5dB way up at 400hz. Modelling a 24" x 24" flat baffle shows a drop of of about 16dB from there to 30hz giving 80.5dB 2.83V at that point. The U baffle or H frame should get back somewhere between 6-10dB efficiency at 30hz which is quite good. It also increases the max output by the same amount. The OB is capable of about 98dB at 30hz, again with the U or H frame giving 6-10dB more maximum output. This requires only 20V input to do so, about 100W. Proper placement in the room will get back several dB more output. The plan is to measure the OB, U, and H all outside. Then bring into our well treated 13' x 21' room with 9ft ceilings and get some measurements at the listening position as well.
That is a lot better than I thought it would be. Will you be posting your results?
Dave
Hello again!
I would be very interested in your results of the H baffle and U baffle baffles. If you can get baffles like that to obtain flat response from below 30hz on up using just a single coil and resistor I'd be very, very interested in knowing more. If you wouldn't mind would you email me the results at: thetubeguy1954@yahoo.com I'd really appreciate it!
I'm Listening to: Across The Rubicon by Silhouette
Thetubeguy1954 (Tom Scata)
Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers
For years I have been using dipole subs.
I began with 2x2 Eminence Alpha-15 subs.
Now I use 3 paralleled 15" Eminence Beta-15A per side. Use a graphic eq. to attenuate the bottom octaves. The attack, clarity end ease these dipoles handle the bass with is outstanding IMHO.
In the midrange I use Supravox 8" FR and a Faital HF driver from 8Hz.
Rgds Jan
Jan,
What's the ohm rating of those 3 paralleled 15" Eminence Beta-15A per side? Also are you saying the bass is so loud at the bottom octaves they actually need to be attenuated? Finally what's the dimensions of the baffle they're mounted on?
I'm listening to: Elixir by Fourplay
Thetubeguy1954 (Tom Scata)
Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers
Hi Tom
The Beta-15A units are 98db/ a piece, so 3 paralleled are quite sensitive.
I think the resulting impedance of the 3 woofers are around 2 ohms which is no problem with the MC2 poweramp I`m using. I have to attenuate the bass system which is easy since there is gain control on the power amp and also on the Eq.
The baffle is 160cm high and 54cm wide with small wings like this
I___I
The wings are 12,5 cm. They function as kind of stabilization and also works to broaden the baffle.
Rgds Jan
Jan,
It sounds like you're quite happy with your OB, dipole subs. I had never heard of the MC2 power amps but I just checked them out and they look like they'd be very good to use as subwoofer amps. Thanks for your input...
I'm Listening to: Across The Rubicon by Silhouette
Thetubeguy1954 (Tom Scata)
Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers
Tom,
Have you ever thought if a real, true, infinite baffle sub woofer installation would be possible in your home ?
Scott I live in a manufactured home and don't see where or how I could install a true IB subwoofer system in my home.
I'm listening to: Elixir by Fourplay
Thetubeguy1954 (Tom Scata)
Central Florida Audio Society -- SETriodes Group -- Space Coast Audio Society
Full-range/Wide-range Drivers --- Front & Back-Loaded Horns --- High Sensitivity Speakers
A false wall built a couple feet inside the original wall? Or little speaker "sheds" mounted on the outside walls? (^;
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: