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Open Baffle Epiphany!

I only use line level RCA's into the plate amps.

The splitter shown above ( found it as an image on the net ) I've used at the CDP outputs to feed it's signal to two separate amp's inputs. It's a good way and a cheap way to bi-amp OB's without a preamp.
 
Compared to box speakers, open baffle speakers are far more room friendly. They work for me in my many windowed room whereas the Zu's couldn't.

If you want to get a taste of the OB sound take your box speakers outside and listen to them with your back against the wall of the house. You'll hear openness that OB's have without the room coloration.
 
I'm amazed at some of the knowledge being offered in this thread, I hope there is a way we could make it a sticky because I would hate to see all this great information get buried in the speaker forum.

For those that have done the H frame - Has anyone measured the F3 yet? I'm picking up my Alphas Thurs and am planning on doing an H frame where the front part folds into itself when not in use - for high WAF :D

Also, if your ears (and eyes) are out of view of the woofer, for instance if you are standing close to the speakers and cant see into the woofer cavity, do you notice and loss of upper bass frequencies? How directional are the woofers?

Something tells me that what we are seeing today is just the start of open baffle technology, I can't imagine what ingenious designs some folks will come up with in the future!

Looking forward to recycling my cardboard baffles and going full throttle into the real deal!
 
Poultrygeist said:
Unlike the box sub I was able to integrate the H-frames with the folding wing Betsy's. Perhaps because they're both open baffles or maybe the Velodyne was problematic? But I suspect it's because the H-frames are so speaker friendly.
Click to expand...

I have to agree with you, when I had my Paradigm sub and the FE103a's in OB there was a separation in the voice of the speakers, but when I added OB woofers the two just blended together beautifully.
 
sempai said:
On Siegfried Linkwitz's site he recommends that speakers be placed at least 3' from reflective surfaces and that a delay of greater than 6 ms of the first reflections is required to perceptually mask them.
My point source speakers are slightly tighter to the sidewalls (out of necessity) than this with about 4' behind them. This changes frequently as I struggle to find the optimal placement in my smallish room.
Open baffles are very room dependent and very sensitive to placement.
Moving them forward and backward you can hear the bass appear and disappear.
Changing the toe-in you can hear the tonality change. More toe-in = greater tonality, less toe-in = less tonality. I'm finding that changing the toe-in by fractions of an inch can make an audible difference.
Some people suggest that closer coupling to side walls benefits your sound in that the walls become an extension of the baffle in the same way that the floor does with drivers that are positioned lower.
There seems to be no end to theories on placement with open baffles.
Experimentation seems to be the key.
It would appear that the rule is free standing out in the room is better.
By at least 3 feet.
But don't feel bound to those measurements.

Other than the research done by luminaries Siegfried Linkwitz and Michael K. King there seems to be little scientific study on dipole speakers.
So hard and fast rules are hard to come by.

It's like the wild wild west out there.

Art
Click to expand...

There are some hard and fast rules.....

1) The boundary layer behind the speakers should not be absorptive. Reflective is preferred and diffuse is better. 1D quadratic diffusion is optimum.

2) A minimum of three feet spacing should be established from the back of the driver to the boundary layer behind it to establish the proper delay in arrival time (to the listener) between content dispersed directly from the front of the driver and reflected content fired from the rear of the driver.

3) Because the radiation pattern of a dipole is in a figure-of-eight pattern, or having two identical lobes with one firing to the front and one to the rear (out of phase with one another), there is cancellation directly perpendicular (to the sides) of the baffle. This reduces interaction with the boundary layers to the sides and therefore reduces the detrimental effects of early reflections that are generated from those locations.

And there has been much research conducted wrt dipoles. SL and MJK are great sources for some of this research, but they certainly haven't been the only "players". It's not really as much of a "black science" as you are suggesting.
 
cptnCanada said:
I'm amazed at some of the knowledge being offered in this thread, I hope there is a way we could make it a sticky because I would hate to see all this great information get buried in the speaker forum.

For those that have done the H frame - Has anyone measured the F3 yet? I'm picking up my Alphas Thurs and am planning on doing an H frame where the front part folds into itself when not in use - for high WAF :D

Also, if your ears (and eyes) are out of view of the woofer, for instance if you are standing close to the speakers and cant see into the woofer cavity, do you notice and loss of upper bass frequencies? How directional are the woofers?

Something tells me that what we are seeing today is just the start of open baffle technology, I can't imagine what ingenious designs some folks will come up with in the future!

Looking forward to recycling my cardboard baffles and going full throttle into the real deal!
Click to expand...

You should email (or pm...he's a member here) MJK about F3...or maybe try the MathCad worksheets he makes available on his website.

Open baffle technology is older than monkey coffin technology. There's just a lot more info out there on monkey coffins because they're easier to implement in a domestic environment which, of course, makes them easier to market and sell.
 
The reasons open baffles haven't made it commercially has nothing to do with sound and it's a fact that most buyers put more stock in appearance than performance.

The weak bass criticism doesn't hold water. With the wide spread use of high Q pro woofers, OB bass it's now an advantage.
 
True, open baffle system are one of the oldest ways to project sound. Back in the day I don't think there was much science behind the theory, just like the early acoustic suspension, and bass reflex of the day, they were crude in design. Over the years manufactures have put millions into perfecting these two designs, and there are now thousands of variations out there that sound terrific.

Open baffle, used in early consoles, etc, was mostly abandoned when manufacturers went for the box type speakers we know today. Do box speakers sound better? You have to hear OB to be the judge. It seems like only recently that there has been a renewed interest in OB speakers, and it looks like there are a few very nice commercial OB's being produced such as Decware's ZEN OB which seems to take it to the next level.

The idea being, with live music there is more than two points of sound, as there is with traditional box speakers. I think OB speakers (i.e.dipoles), with my limited experience, open up the soundstage from two focal points and attempt to create a soundstage that equals the entire area in front of the listener. When I hear music being played live in front of me, this is how I hear it. Not to mention box colourations, etc, etc ...

Tomlinmgt, you are correct that monkey coffins would be probably be easier to commercially sell than an open baffle design, but I do think public views can evolve; once the sheep see the light things change pretty fast. Think vinyl and its premature demise. Im sure if Polk or Klipsch came out with an OB system mass marketed in big box stores that got great reviews, opinions would change..of course it would have to have some serious eye candy to appeal to the un-edumacated masses.

Until then, I'm happy to listen to my cardboard OB's while enjoying a fine Canadian malt beverage. Wait, one of the boxes is starting to keel over, better go prop it back up! :beer:
 
tomlinmgt said:
There are some hard and fast rules.....

And there has been much research conducted wrt dipoles. SL and MJK are great sources for some of this research, but they certainly haven't been the only "players". It's not really as much of a "black science" as you are suggesting.
Click to expand...

Didn't mean to suggest that it was a black science.
There is however a great deal of anecdotal information being passed off as research.

A great source of information explaining the science behind open baffle in a way that makes sense of all the variables involved in a way that is understandable to those of us that are new to the game is this site :

dipolplus.de

It should be noted that the author of the site makes extensive use of the MJ King Worksheets.

My apologies to Mr. King for referring to him as Michael K King in my previous post.
I have gone back and corrected the typo.

Art
 
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Really the only sticky we need is a reference to MJK's Quarterwave website. The basic dimensions are there for flat baffles and H-frames.
 
Didn't want to see this thread die so here's a Frankenstein OB I had fun stitching together.

The big silver FR driver is a Zenith alnico pulled from an old console. I added some PE buy out Pioneer horn tweeters and attached everything to some Alphas
I had been using as stand alone bass augmenters.

Hiding inside those old open back consoles are some OB worthy full range drivers. :yes:




picture.php
 
I'm just gonna grab some old speakers, stick em in some cardboard, hook em up and see what happens. Then if it sounds good maybe use a nice piece of veneer plywood.

This looks way more satisfying than last winters "" Why don't I spend every weekend working on prototypes for my own Lounge Chair design that will never be as comfortable as an Ikea Poang" adventure.
 
Poultrygeist said:
The reasons open baffles haven't made it commercially has nothing to do with sound and it's a fact that most buyers put more stock in appearance than performance.

The weak bass criticism doesn't hold water. With the wide spread use of high Q pro woofers, OB bass it's now an advantage.
Click to expand...

There are some beautiful OB's out there, check this OB gallery thread, if you haven't already. Look por posts 1143 and 1149, among many others.

I agree regarding your comment about bass performance, but the reality is that if you have woofers with low QTS, you can always go hybrid, and do a semi open baffle or a vented/sealed enclosure for them, leaving the other drivers in the OB configuration.
 
PR Audio said:
There are some beautiful OB's out there, check this OB gallery thread, if you haven't already. Look por posts 1143 and 1149, among many others.

I agree regarding your comment about bass performance, but the reality is that if you have woofers with low QTS, you can always go hybrid, and do a semi open baffle or a vented/sealed enclosure for them, leaving the other drivers in the OB configuration.
Click to expand...

Great link!
Great thread!

Going over there now to spend some more time.

May not be back for a while.

Thanks PR.

Art
 
PR Audio said:
There are some beautiful OB's out there, check this OB gallery thread, if you haven't already. Look por posts 1143 and 1149, among many others.

I agree regarding your comment about bass performance, but the reality is that if you have woofers with low QTS, you can always go hybrid, and do a semi open baffle or a vented/sealed enclosure for them, leaving the other drivers in the OB configuration.
Click to expand...

There are some great looking OB's in that thread. I see that Nelson Pass also has a pair of Lowther/Alpha's ( post #19 ).

Going hybrid with low QTS woofers in a box is an option but you lose out on the magic of OB bass.
 
Great thread! I am cleaning up the garage today, tomorrow I am going to buy some plywood and get a pair of betsy's singing again! I like the Target box idea for bass reinforcement! those alphas are very reasonably priced, but I have some car woofers I may experiment with first. and I will need a plate amp. I also have a Audio Control EQX crossover and EQ that run on 12 volts that may be my active xover. any thoughts?
 
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