OB Newbie- Lots of questions

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Built speakers before, but never OB. Was thinking about using a 12 or 15 inch coaxial for mid and upper duties with 2x15 inch for bass duties. Was thinking about possibly a Selinium or Radian or possibly if i can get a Tannoy DC. Wondering what the sound quality is like compared to each other and any other possible contenders. What does the inbuilt tweeter compare like to say, a normal separate tweeter? Was thinking about maybe using the Dayton RS 15's for bass. How would two of these per channel in parallel work with the above in regards to sensitivity? When choosing woofers, do you get sensitivity increase in OB when connected in parallel as you do with normal boxed speakers i.e. 6db increase?
Thx.
 
Hi,
You're right.
+3 dB with 2 drivers
+6 dB with 4 drivers
BUT the amplifiers has to be able to handle the lowered impedance.
I've choosen for my own project - just begun - an Executionner 21': enough sensitivity, low Fs and high Qts :D
I'm still brainstroming about baffle shape and about mouning drivers.
All the best,
Alain
 
Alain Favret said:
Hi,
You're right.
+3 dB with 2 drivers
+6 dB with 4 drivers

Nope.

If two drivers are connected in parallel, you get a 6 dB sensitivity increase for low frequencies in all directions, and also straight in front of the loudspeaker for high frequencies. Four drivers in parallel results in a 12 dB sensitivity increase.

If the drivers are connected in series, the sensitivity remains the same (0 dB), and if four drivers are connected in series-parallel, the sensitivity increase is 6 dB.

There are quite a few old threads on this, I think. One thread even ended up with someone doing the experiment, I don't remember who it was now.
 
Go here;

http://www.linkwitzlab.com/

Mr. Linkwitz is "the" expert when it comes to OB speaker designs.

Actually, from my understanding, efficiency for Dipole woofers drop by 6 db as frequency falls. That's why EQ increasing at 6db per octive must be applied from roughly 140hz (maybe 200 Hz - I don't remember) and below. The only real solution is incredibly high efficiency woofers with low Fs, like a TAD TL-1602 or multiple 12" woofers with low Fs. That's why Mr. Linkwitz prefers the Peerless XLS woofers. They have a very low Fs and have superior distortion performance.

Also, try here;

http://www.mfk-projects.com/index.htm

Monte Kaye is the author of this site. He is related to owners of the Autio Artistry. The makers of the venerable Beethoven OB commercial speaker.

I too am in the process of a similar design. So, here is the problem; It's not easy to find but as you read about OB designs you'll begin to see that overall output (Orions) and the power of the Bass reproduction are an underlying complaint about this design.

As open as the sound is few are satisfied with the overall bass response of these designs. So, to compensate many wil create large bass arrays of 4 or 6 woofers per side. I view this a terrible option. I have a very large listening room and I still don't have the space for such behemeths.

Mr. Linkwitz himself has now finally settled on stereo sealed (and EQ'd) subs for ALL of his listening (whether home entertainment or music listening). He has revised what he considers a proper crossover frequency from 40Hz to 50Hz. Also, in order to meet his needs for adequate SPL he is now recommending a rear firing tweeter.

I, as a result, have gleaned the following; SPL is a problem for these speakers. I also believe that, since SPL is a problem, the tweeters are crossed too low (1400 Hz). I also believe that the demands placed upon a single 8" midwoofer are altogether to high further preventing relaxed high SPL performance.

As a result of this, combined with Monte Kaye's finding, I believe that this should be designed as a 4 way system. The Sub-Bass being handled with an appropriate subwoofer. For myself I've decided the Servo Sub will be my choice as the base of the front two speakers. 2 15's will operated from 60Hz (maybe up to 80Hz) and below. The panel will be the remaining 3 way speakers.

Two 8" will operate from 60Hz to 300Hz. Mine are Cabasse 21 NDC woofers. They are 91 db efficiency so two will give me 94 db efficiency. These are quite unique with a Fs of 32Hz and a very high x-max. VERY low MMS so they'll be very fast.

For my system, a single Focal 6 WM from 300-3000 Hz. I'm feeling a little unsure about this one. Yet, Lynn Olson, Rod Elliott and others constantly comment on NOT crossing over in the primary listening frequencies of 300-3000 Hz. A better choice might be the PHL midranges. They are notoriously flat and have similar sensitivity. I'm going to make every effort to abide by that advice (no crossovers in the 300-3kHz region).

Many, if not most, believe a driver that is larger that 5" cannot adequately do this with precision (hence the Jamo 909). This given driver (Audiom 6WM) has an extremely low MMS at 7 grams so I'm counting on what I've learned from others about how light the diaphram needs to be in defining its ability to reproduce the indicated frequencies with clarity AND dynamics. When it comes to dynamics we all know nothing provides better than size so there in lies the conundrum. What is the best compromise?

For the Tweeter I've purchased the Audiom TD5's. They really are quite exceptional (they better be at their price). Still I'm kind of leaning toward the Raal ribbons to serve this part of the frequency (3k +).

For me the example system in the Perfect 8 system (The Point). Look here;

http://www.perfect8.com/

This system is with +- 1db from 20 Hz to 20kHz. Still I see this system has to lack at either 100-300 Hz or at the top crossover of maybe 2-3Khz. They don't define it, but, they're trying to get a 7" to repsond like a 5" would. I'll guess it's yet another crossover in our primary hearing frequencies (300-3kHz).

Well, you can see the issues that remain common to OB speakers. I believe panel design is critical beyond what has been discussed and don't forget about the EnABL process to assist you. I think this is provides assistance of huge merit. If we can tame driver modes this easily it is a superior way to plan for exceptional speaker response, regardless of the design.

Mine will be powered by individual Tri-Path amplifiers (Tri-Path 2022) per speaker (4), on-board. I will have 5 total speakers and only 2 with the subwoofers built in them. All panels (and their drivers will be "de-coupled). This is not an easy task for the builder. Panels really are not a good environment to mount dedicated amplifiers as well as the associated crossovers/EQ's. I'm still working on this one. All will be driven by a Lexicon MC-1. I doubt any ATC system will be able to sound this good, even at $93k.

Good Luck!

TEH
 
Thx for replies.Alain what are you using for mid and highs.I'm still wondering if anyone has any experience with the Daytons.What about B&C or Beyma coaxials.Or possibly a diy woofer with different compression tweeter.I've read you can change one woofers brand with a different horn if the thread size is the same.
 
Go here;

Linkwitz Lab - Loudspeaker Design

Mr. Linkwitz is "the" expert when it comes to OB speaker designs.

Actually, from my understanding, efficiency for Dipole woofers drop by 6 db as frequency falls. That's why EQ increasing at 6db per octive must be applied from roughly 140hz (maybe 200 Hz - I don't remember) and below. The only real solution is incredibly high efficiency woofers with low Fs, like a TAD TL-1602 or multiple 12" woofers with low Fs. That's why Mr. Linkwitz prefers the Peerless XLS woofers. They have a very low Fs and have superior distortion performance.

Also, try here;

http://www.mfk-projects.com/index.htm

Monte Kaye is the author of this site. He is related to owners of the Autio Artistry. The makers of the venerable Beethoven OB commercial speaker.

I too am in the process of a similar design. So, here is the problem; It's not easy to find but as you read about OB designs you'll begin to see that overall output (Orions) and the power of the Bass reproduction are an underlying complaint about this design.

As open as the sound is few are satisfied with the overall bass response of these designs. So, to compensate many wil create large bass arrays of 4 or 6 woofers per side. I view this a terrible option. I have a very large listening room and I still don't have the space for such behemeths.

Mr. Linkwitz himself has now finally settled on stereo sealed (and EQ'd) subs for ALL of his listening (whether home entertainment or music listening). He has revised what he considers a proper crossover frequency from 40Hz to 50Hz. Also, in order to meet his needs for adequate SPL he is now recommending a rear firing tweeter.

I, as a result, have gleaned the following; SPL is a problem for these speakers. I also believe that, since SPL is a problem, the tweeters are crossed too low (1400 Hz). I also believe that the demands placed upon a single 8" midwoofer are altogether to high further preventing relaxed high SPL performance.

As a result of this, combined with Monte Kaye's finding, I believe that this should be designed as a 4 way system. The Sub-Bass being handled with an appropriate subwoofer. For myself I've decided the Servo Sub will be my choice as the base of the front two speakers. 2 15's will operated from 60Hz (maybe up to 80Hz) and below. The panel will be the remaining 3 way speakers.

Two 8" will operate from 60Hz to 300Hz. Mine are Cabasse 21 NDC woofers. They are 91 db efficiency so two will give me 94 db efficiency. These are quite unique with a Fs of 32Hz and a very high x-max. VERY low MMS so they'll be very fast.

For my system, a single Focal 6 WM from 300-3000 Hz. I'm feeling a little unsure about this one. Yet, Lynn Olson, Rod Elliott and others constantly comment on NOT crossing over in the primary listening frequencies of 300-3000 Hz. A better choice might be the PHL midranges. They are notoriously flat and have similar sensitivity. I'm going to make every effort to abide by that advice (no crossovers in the 300-3kHz region).

Many, if not most, believe a driver that is larger that 5" cannot adequately do this with precision (hence the Jamo 909). This given driver (Audiom 6WM) has an extremely low MMS at 7 grams so I'm counting on what I've learned from others about how light the diaphram needs to be in defining its ability to reproduce the indicated frequencies with clarity AND dynamics. When it comes to dynamics we all know nothing provides better than size so there in lies the conundrum. What is the best compromise?

For the Tweeter I've purchased the Audiom TD5's. They really are quite exceptional (they better be at their price). Still I'm kind of leaning toward the Raal ribbons to serve this part of the frequency (3k +).

For me the example system in the Perfect 8 system (The Point). Look here;

PERFECT8 Technologies

This system is with +- 1db from 20 Hz to 20kHz. Still I see this system has to lack at either 100-300 Hz or at the top crossover of maybe 2-3Khz. They don't define it, but, they're trying to get a 7" to repsond like a 5" would. I'll guess it's yet another crossover in our primary hearing frequencies (300-3kHz).

Well, you can see the issues that remain common to OB speakers. I believe panel design is critical beyond what has been discussed and don't forget about the EnABL process to assist you. I think this is provides assistance of huge merit. If we can tame driver modes this easily it is a superior way to plan for exceptional speaker response, regardless of the design.

Mine will be powered by individual Tri-Path amplifiers (Tri-Path 2022) per speaker (4), on-board. I will have 5 total speakers and only 2 with the subwoofers built in them. All panels (and their drivers will be "de-coupled). This is not an easy task for the builder. Panels really are not a good environment to mount dedicated amplifiers as well as the associated crossovers/EQ's. I'm still working on this one. All will be driven by a Lexicon MC-1. I doubt any ATC system will be able to sound this good, even at $93k.

Good Luck!

TEH

Hello I have a pair of 6WMs doing nothing and would like to put them to use, how did you get on with them?

DM :)
 
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This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.