Fast, fun, Inexpensive OB project

Hi


Thanks for all your positive comments!
Took some time - had to finish my amps PSU tweak first.



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panomaniac said:
Hey Michael - that's great!

I'd love to hear your version, but the hills of Austria are just a little too far from the hills of Hawaii. =)


Nice work. And thanks so much for the graphs and measurements - they go a long way to explaining what is going on. What is the crossover software you use?

I'm suprised at how flat you got it. Just seems to be a peak at 3Khz. Cone break-up? Baffle nasties?

My main question would be this:
Given that your measurements show flat (more or less) at 1M in front of the baffle, do they not sound too bright in room? Is there a lot of mid energy coming off the back of the Peerless and filling the room?

The original pair have a big midrange dip in the crossover to counter the midrange energy coming from the back. I see that your soft crossover does the same thing, but the resulting FR looks a lot flatter than I would have expected!

Thanks for pursuing this fun little speaker. Maybe it will encourage others to give it a try.



Paniomaic, the plots shown in my last posting are " in room " measurements. They show what the speaker does AND what the baffle does AND what the room does at a SPECIFIC position of the speaker AND the mic.
Please don't interpret too much from them. It wasn't meant to be scintifically but just to have a good startoing point for own experiments on a active setup with the Behringer DCX2496.
It shows that there is relative good balance obtainable with not very much effort. And that the original XO can be translated to active amping with remarkable little change.

It was a "quick and dirty" setup though, within half a day – included buying the material and producing some sawdust - heavily based on measurement and not so much on listening. Though it turned out pretty well, everybody is invited - and actually SHOULD – tweak it to his / her taste.

The brightness expected isn't there, maybe the result of the rear tweeter ( IMO its ALWAYS of benefit so I didn't even try without ) but the tweeter for me was too early unless I delayed it.





terry j said:


Hi michael, could you (and others) comment on this please. I'm curious about using white/pink noise when setting up speakers to be flat.

Basically, when do we use which?? They are very different sounds, and so when we make the speaker flat on each, well they will sound very different won't they??

Additionally, what is the difference again if we use a swept signal?

..........


TerryJ, the stimulus depends on the measurement used.
For a RTA you use pink noise to get flat reading, for FFT you use white noise for flat reading ( be aware not to overload the tweeter ! ).

Usually FFT is NOT used without windowing but you can do so and basically you get whatever is in your room at the place of the mic.

Swept signal is a good stimulus for distortion measurement at close micing. I don't use it for FR measurement.






Bratislav said:


I was curious about this too, and your guess is spot on. Would experimenting with baffle edge (making it progressively narrower, to a point) help, or should we attack it differently (moderate Q anti resonant LCR targeted at 300Hz) ? I'm extremely intrigued by this development as I still like the idea of multiple SLS's on a large-ish baffle as bottom end of a Arvo/R909 like 'clone'.

Bratislav

Bratislav, no need for correction at 300 Hz - its an artefact.




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I did some FFT measurements that exclude the room.
Naturally it reveals a lot of details one normally doesn't like to see, though we have to keep in mind that a good looking FR has NOTHING to do with good sound from a speaker.




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This plots show the Peerless SLS12 without XO but with the high shelfing EQ.
What can be seen is that there is NO stored energy at 300 Hz. Though the window used limits the valid FR range to above 300 Hz – indicated with the yellow bar at the X-axis – we would see a severe peak for sure.

What jumps into the eye are the resonance in the cone break up region.




Greetings
Michael
 
Hi


For those who have a DCX and would like to give that nice design a try here is the setup for kind of improvement in the cone brake up region.
Though my impression is that you trade in slight refinement in terms of imaging and tonality against unique character and fun factor.





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A setup file for the Behringer DCX that you can downloaded from my site :
http://members.aon.at/kinotechnik/d...nita_12/sls/peerless_SLS-Millenium_tweak4.xpc



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The EQ'd Peerless rolls off more early and this has to be compensated by a lower XO frequency for the tweeter at around 1100 Hz or so.
Again its only meant as a good starting point for own experiments.

It would take a LOT MORE time than I had to provide a really sophisticated XO / EQ tuning to bring out all the strengths the Manzanita 12s is capable of and I am quite sure the original passive setup still is superior in this respect.

Greetings
Michael
 
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Thanks Michael for posting your results. Very encouraging.

So those are screen shots of the software interface to the DCX2496? I've used the DCX, but never the software. Looks very handy.


mige0 said:
The brightness expected isn't there, maybe the result of the rear tweeter ( IMO its ALWAYS of benefit so I didn't even try without ) but the tweeter for me was too early unless I delayed it.


As orgianlly built, there is no britghtness, unlike a lot of full range speakers. Good to know that your different tweeter gives you good results, too.

Not sure what you mean by the "tweeter was too early." Do you mean the front facing or rear facing tweeter? The passive crossover design takes the driver alignment into account by spreading the LC values a bit, so some delay on the active crossover would make sense. But if you mean the rear tweeter, then that's another matter. :)
 
panomaniac said:
Thanks Michael for posting your results. Very encouraging.

So those are screen shots of the software interface to the DCX2496? I've used the DCX, but never the software. Looks very handy.

I had someone setup a dcx in my system, using the buttons on the front panel. Talk about a nightmare to understand.

However, using the interface on the computer it was as simple as pie, very easy to grasp and understand.

You can download it and just muckabout (no unit hooked up) and get a feel for it, very much recommended.

thanks Michael for the explanation.
 
Hi

panomaniac said:
Thanks Michael for posting your results. Very encouraging.

So those are screen shots of the software interface to the DCX2496? I've used the DCX, but never the software. Looks very handy.





As orgianlly built, there is no britghtness, unlike a lot of full range speakers. Good to know that your different tweeter gives you good results, too.

Not sure what you mean by the "tweeter was too early." Do you mean the front facing or rear facing tweeter? The passive crossover design takes the driver alignment into account by spreading the LC values a bit, so some delay on the active crossover would make sense. But if you mean the rear tweeter, then that's another matter. :)



Panomaniac, yes the Millenium works well, though probably the Seas 27TDFC might blend even better – do not know. Its pretty close in data and FR only slightly less excursion.

http://www.bmm-electronics.com/document.asp?document_id=1702&link=datasheets\seas\h1189.pdf
http://www.bmm-electronics.com/document.asp?document_id=596&link=Datasheets/seas/t25cf002.pdf


You can vary the phase by tweaking the XO but sound wise its not exactly the same as delaying the tweeter. At least this is my impression.

The rear tweeter is not dominant, its ~ 3-6 dB down in SPL and just there to illuminate the room. Better stage and more natural ambience are my findings here.





terry j said:


I had someone setup a dcx in my system, using the buttons on the front panel. Talk about a nightmare to understand.

However, using the interface on the computer it was as simple as pie, very easy to grasp and understand.

You can download it and just muckabout (no unit hooked up) and get a feel for it, very much recommended.

thanks Michael for the explanation.



Spot on! Its a pain to do all manually.
I made the my DCX setup file available to give a VERY quick entry to what I did for everyone interrested.
:)


Greetings
Michael
 
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Re: Re: Simple cheap OB's

panomaniac said:

An externally hosted image should be here but it was not working when we last tested it.


These have a circular central cutout... not the bestr shape. You'd do well to incise a star -- even just 3 points (i like 11 & 13) -- for much wider distribution of the srface wave off the inside of the ring.

Something like this:

felt-star-BD-pipes.jpg


dave
 
hi panomaniac,

nice OB design! Did you ever think about using a waveguide with the tweeter?
I'm using a seas 27TDFC/TV in the Monacor WG-300 (7" waveguide), the directivity works pretty well with 8" and stiil with 10" woofers, I haven't tested 12" yet.

Here two quick and dirty graphs of the tweeter without and with waveguide in a small testbaffle (~14" x 11.5")

without waveguide
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with waveguide
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edit: 0°, 15°, 30°, 45°, mic distance round about 30"

cheers,
LC
 
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lovechild said:
nice OB design! Did you ever think about using a waveguide with the tweeter?

Thanks LC. It's a great sounding design. Wish I could take credit for it, but all I've done is document it. =)

I don't know if a waveguide would be much help in this design. The tweeter has to be padded down so much that the gains might all be traded away. (Not if bi-amping). What advantages other than efficiency gain do you find with the wavegude?


MisterTwister said:
has anyone tried to remove dust cup and put phase plug in SLS 830669 ?

That would be a big phase plug! Might be worth a try, but I'm like you - don't want to be the fist to try it....
 
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Thanks! It's a great sounding speaker, excellent tonal balance.

I guess it cold be turned into a floor stander. But the longer baffle will give you a different EQ, you'll get a bit more bass and a different F-peak and F-equal. So the crossover will have to be adjusted to suit. Might need a little smaller R on the tweeter, as the bass will now be stronger.

You'll need to play with the crossover some, for sure. But what's there will be a good start.

FWIW, I'm running a similar rig now. 16x35" sitting on the floor. Different drivers, so different x-over points. But the overall response seems similar.
 
I've been looking for a fairly inexpensive speaker project for my mains, and these look like a good fit. Unfortunately, I have very little experience in speaker building and none with open baffles. What kind of work would I have to do to the crossover if I made floorstanding baffles? I'm curious if the off-axis response is any good, I like to listen lying down on my couch, so I need a speaker that can match my laid-back disposition :) . Also, how would these compare to say planet10's modded b200s on an open baffle.

Thanks in advance for answering an inquisitive novice's questions.
 
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Hi-

I don't think the floor standing part would change much, except maybe to pitch the tonal balance down some, i.e., give you some more low midrange. The crossover as described would be a good place to start. I'll ask JB what he thinks, as a number of people would like this as a floor stander.

Off axis response is pretty good, they seem to have the same sonic signature over a wide are of the room, so I don't think it's a worry.

As for how they compare to the B200 on open baffle, I can only guess. Having heard the 8" Hemp solo on open baffle, I can tell you I'd take the Manzanita-12s hands down, no contest. But I have not heard the B200 so can't really judge.
 
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Thanks for the graph, Pete.

Yep, that looks about right. Making the baffle taller gives you a bigger F-peak and some more energy in the mids. That's going to change the tonal balance some, so you may, or may not want to juggle crossover values a bit. Looks like about 1dB difference, so it shouldn't be a big deal.

When (or if) I find a good answer to the shift, I'll be sure to post it.
 
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Just for fun I ran the response of the Peerless woofer on 2 different baffles sizes to compare.

Green is the original baffle, Red is a 1M tall baffle (puts the tweeter at ear height when sitting).
As you can see, only about a 1.5dB gain. So it should be easy to handle. Maybe just a smaller resistor on the tweeter to make up for the slight gain from the 12".

Note that the graphs are before any EQ and the side wings are not accounted for.
 

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Bizwacky said:
Also, how would these compare to say planet10's modded b200s on an open baffle.

Given that no-one, not even me has heard the latest version of my B200, comments will be scarce :)

The 1st of the new drivers just needs the phase plugs EnABLed and then they are off to Oz.

At the fest this summer, the concensus was that the B200 with phase plug killed the FR8c on an OB, but that is not a fair comparison because the B200 is designed for OB, and the FR8c is ill-suited (that was also before the FR8c got a whizzerectomy, phase plugs and a bit of noise lowering C37.

How it compares to a well done cheap, "conventional 2-way" on an OB i could only guess.

dave