AudioCircle

Audio/Video Gear and Systems => Open Baffle Speakers => Topic started by: MJK on 15 Sep 2007, 06:31 pm

Title: Design of an Open Baffle Speaker with Passive Crossovers
Post by: MJK on 15 Sep 2007, 06:31 pm
I have posted a new article on my site documenting an OB speaker design study I have been working on for the past six months. Basically it shows some of the trade-offs that need to be made to select an appropriate woofer driver, baffle size, and crossover to produce a balanced SPL system response. If interested, you can find it under the General Speaker Related Articles link.
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Scott F. on 15 Sep 2007, 08:21 pm
Very nice job Martin  :thumb:

I still haven't had the gumption to try a true open baffle (including the woofer). One of these days I may start playing around with it after I've had my fill of the BR bass. Your article will be a good guide for where I need to start  :green:
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: opnly bafld on 15 Sep 2007, 08:30 pm
Very nice job Martin  :thumb:

I still haven't had the gumption to try a true open baffle (including the woofer). One of these days I may start playing around with it after I've had my fill of the BR bass. Your article will be a good guide for where I need to start  :green:

Have you had a chance to listen to Bob's system?
OB bass is  :thumb:

Martin,
Thanks for taking the time to research and document the information.

Lin
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Scott F. on 15 Sep 2007, 08:39 pm
Have you had a chance to listen to Bob's system?
OB bass is  :thumb:

Yeah Bob, wheres the invite  :scratch:  :rotflmao: :rotflmao:
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Danny Richie on 16 Sep 2007, 12:53 am
Hey Martin,

I noticed a couple of things that I would like to point out to you.

1. There is no "T" in Danny Richie

2. Our OB-5 and OB-7 designs are completely passive. No active crossovers or EQ filters are needed.
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: MJK on 16 Sep 2007, 01:44 am
Danny,

Sorry about the mistakes, I'll update the article tomorrow.

Martin
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Bob in St. Louis on 16 Sep 2007, 12:23 pm
Have you had a chance to listen to Bob's system?
OB bass is  :thumb:

Yeah Bob, wheres the invite  :scratch:  :rotflmao: :rotflmao:

Lin, Thanks for the complement man.  :wink:
Scott, Regarding the invite: I suppose "third times a charm" as they say.  :lol:
Martin, Thanks for the article. Skimmed so far. Will re-read when time allows.

Bob
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Bob in St. Louis on 17 Sep 2007, 03:58 pm
Martin,
If I may, with all due respect, I'd like to make a correction regarding the Hawthorne Audio Duet.

Found in your first paragraph regarding Active XO'd OB's:
Each features active crossovers and EQ filters requiring at least two amplifiers.

And in comparison the passive XO'd OB's found in your second paragraph:
Being passive crossover designs, these speakers do not have requirements for sophisticated electronic filters and multiple amplifiers.

You are correct in that the Duets do not require "sophisticated electronic filters", but they do require two forms of amplification. The top driver is a coaxial design. A 'mid-woofer' with a compression tweeter in the rear. These are the two drivers that required the built-in (and included) XO network. The lower driver "Augie" (bass augmentation driver) is a stand alone driver. Meaning it is in no way "electrically associated" with the top driver(s). No XO exists between the Augie and upper Coaxial unit.
So minimun two channels of amplification are needed for a pair of Duets.

A factory build pair of Duets come equipped with three sets of inputs on the back panel. Minimum of two are required to power all of the drivers. However, some folks choose to eliminate the factory XO and utilize the third set of inputs jacks to effectively tri-amp. Powering the compression tweeter separately.
With this option, a third amplifier would be needed.

Duets can be very simple in implementation, or as complicated and complex as the user wishes.
Versatility, and adjustability at it's best.  :wink:

Thank you for your time Sir. Hopefully I've explained well enough.


Bob
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: MJK on 17 Sep 2007, 04:49 pm
Bob.

Thanks for the heads-up. I'll swap the reference to the Hawthorne Audio Solo.

I am taking lots of flack over this article, what a pain. I think this will be the last document I write on OB speakers for quite a while. I'll go back to TL's and horns.   :D

Martin
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Bob in St. Louis on 17 Sep 2007, 05:11 pm
I think this will be the last document I write on OB speakers for quite a while. I'll go back to TL's and horns. 

No Sir... Don't you dare.   :nono:
In fact, I'd love to see what you could do with a bare pair of Hawthorne Audio Coaxials and complementing pair of Augie's.
I've been waiting patiently a very long time for this.  :wink:

Bob
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: MJK on 17 Sep 2007, 05:32 pm
In fact, I'd love to see what you could do with a bare pair of Hawthorne Audio Coaxials and complementing pair of Augie's.
I've been waiting patiently a very long time for this.

Bob,

I am sorry but I don't think that is going to happen. I have the rough design of the three way OB like the Jamo worked out, I probably will finish that design and then actually build it.

I also have a back loaded horn build started in the basement and plan to spend a lot of time on that set of speakers.

Too many things to do and not enough free time.

Martin
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Bob in St. Louis on 17 Sep 2007, 06:09 pm
I am sorry but I don't think that is going to happen.

I understand Martin.  :cry: No really....  :cry: I'll be ok....

Maybe someday. I'm patient.  :wink:

What drivers do you have in mind for the three way (or is it a secret)?

Bob
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: doorman on 17 Sep 2007, 09:19 pm
There are a number of drivers and configurations to implement OB's OB's. Coaxial's being only one! The Visatons are worth a listen.
                                                                                    Don
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Bob in St. Louis on 17 Sep 2007, 09:22 pm
???? What ????  :scratch:
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: MJK on 18 Sep 2007, 12:39 am
What drivers do you have in mind for the three way (or is it a secret)?

Hi Bob,

For right now I am going to keep the limited details I have worked out to myself. This is a project in its early stages and I really don't want to start discussions of how or why I might make any decisions. Heck, even my wife does not know yet (actually, she does not care).

Martin
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Bob in St. Louis on 18 Sep 2007, 01:03 am
Martin, Understood. (especially the part about the wife)  :wink: Please keep us posted.

Don, Thank you. I've heard them. They do sound very nice, however what I've chosen is what sounded best in my opinion. I've made my decision and have zero desire to switch manufactures. My selfish (jovial) pleading to Martin was merely to see what a man of his calibre is capable of with the drivers I own. Call it, "an experts perspective that relates to me", if you will. I like his open baffle papers and have learned much from his writings.  But will never implement anything he does unless they are with the drivers I have.
(interesting how you were able to change your post without the 'edit' line showing as evidence. Neat trick, I'll have to learn that one.)

Bob
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: el`Ol on 18 Sep 2007, 08:38 am
In fact, I'd love to see what you could do with a bare pair of Hawthorne Audio Coaxials and complementing pair of Augie's.
I've been waiting patiently a very long time for this.  :wink:
Bob
Do these two drivers really belong together?
In my eyes the Silver Iris is for people who have the space for huge OBs and the Augie is for people who can live with lower sensitivity or go active.
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: scorpion on 18 Sep 2007, 10:19 am
Martin,

I am glad to have put you on this track, excellent paper as usual !
By chance I just got a pair of 15" from Germany for a similar design, A&D 1524, Fs 44, Qts .7 and Cast Frame Basket that will be paired with
Monacor 130X/8 fullrangers passively. All simulated with your Math Cad model and with on paper very similar results. We will see when they are finished.  :D

/Erling
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Bob in St. Louis on 18 Sep 2007, 12:23 pm
Do these two drivers really belong together?
In my eyes the Silver Iris is for people who have the space for huge OBs and the Augie is for people who can live with lower sensitivity or go active.
Yes el`Ol, I do believe so. The high sensitivity and precision of a tube amp driven coaxial unit mixed with the large Augie run from a powerful sand amp for lower end, open baffle grunt seems a match made in Heaven. Multiple Augie's per channel help raise the effective sensitivity as well. I have no complaints el`Ol, and from the folks that have heard the system they didn't seem to have any concerns regarding the synergy of the two drivers.
Regarding the size of the drivers, yea they aren't small by driver standards, but when you look at the required baffle size of an 8 or 10" driver, in some cases the Hawthorne drivers can actually have a smaller footprint. I've run the Coaxials "baffleless" (mounted like a stop sign), crossed the Augie's over a little higher and had amazing imaging and crystal clear clarity. Something that in my opinion diminishes as the baffle size increases. My current 'baffle' consists of a 2" ring around the coaxial driver so my baffle width is 19" wide. The Augie baffles are 21" wide.

Bob
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: el`Ol on 18 Sep 2007, 01:35 pm
I just visited the Hawthorne Audio website and saw they now also have a 10" coaxial. Better than letting a 15" run into the midrange in principle. But what I don`t understand: Why do they sacrifice sensitivity due to an Fs of 40Hz (knowing almost nobody of their customers uses them in large baffles)?
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Bob in St. Louis on 18 Sep 2007, 04:42 pm
el`Ol, Unless I'm missing something, the Fs of 41.8 of the 10" is identical to the 15". The drop in Spl of 1.6Db would seem almost irrelevant....no?? Of course being a HT guy as well as 2 channel, I have a little knob that makes up for small Spl differences. But even so, 1.6 shouldn't be too big of a worry.
BTW I have a pair of the tens for rear surround duty.

Bob
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: MJK on 18 Sep 2007, 11:15 pm
I am glad to have put you on this track, excellent paper as usual !
By chance I just got a pair of 15" from Germany for a similar design, A&D 1524, Fs 44, Qts .7 and Cast Frame Basket that will be paired with
Monacor 130X/8 fullrangers passively. All simulated with your Math Cad model and with on paper very similar results. We will see when they are finished.  :D

Erling,

Thanks for the positive feedback, it is greatly appreciated.

When you are done with your OB design and build the speakers, send a picture of them for my gallery. I don't have many OB designs shown in the gallery.

Martin
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: stereogeek on 22 Sep 2007, 01:41 pm
Martin-

Good work! It's always interesting to see what the "gurus" of the hobby come up with.My next project will be a pair of Alpha 15's and a pair of Neo 8's I have sitting around.Your paper will aid in my design.


Bob-Sic Em!!! good to see you over here at AC standing up for the cause!

Steve :D
Title: Re: Design of an Open Baffle Speaker with Passive Crossovers
Post by: Bob in St. Louis on 22 Sep 2007, 01:56 pm
Bob-Sic Em!!! good to see you over here at AC standing up for the cause!
Thanks Steve, but I think el`Ol would kick my butt in an all-out debate, he's much more knowledgable.
I'm treading lightly.  :lol: Real glad he's had no rebuttal (as of yet)  :wink:
I just know how good my rig sounds and have to defend it.  8)

Bob