The return to open baffle madness....

tomlinmgt

tomlinmgt

Lunatic Member
Madness because, with just a little forethought regarding driver choice, getting impressive results is just too damn easy. Easy in the sense that I'm also building cabinets for another speaker project and that is friggin' beat down.

Decided to try out my new Jasper circle cutting jig Sunday evening and the first two cuts I made in some scrap OSB turned out so good I wound up cutting out baffles, making stands and mounting a few of the Tang Band 1808's I recently acquired. I had the u-frames already made up and the AE Dipole 15's already mounted so I combined the package to see if a quick throw together of some well-regarded drivers could result in anything worthwhile. I let the TB 1808's play by themselves while I was hooking up the Ashly active for the u-frame subs and that 1808 is a really nice sounding unit from top to bottom...and there is a bottom. It's the first FR driver I've ever messed with and with the exception of still being a little ragged around the edges (because it's brand new) I enjoyed what I heard from it. When paired with the Dipole 15's in the u-frame subs (crossed at around 75) the package has a ton of potential. I've done no measuring so all adjustments were just by ear and there is still a good bit of tweaking needed to dial them in. But even in its unrefined state the combination is a lot of fun to listen to with the u-framed Dipole 15's being very close to dialed in as they sounded almost identical to my DRC filtered distributed bass rig....which I had of course turned off....and reminded me why I like h/u-frame subs so much.

The 1808's are running full range in a 24" wide baffle and are being driven by a TAD-60 with KT-88's operating in triode (so a little over 30 wpc). I tried the F5 with them also but it wasn't warmed up and sounded thin compared to the tubes.

The Dipole 15's are 4ohm DVC units and are being driven by a Threshold s/300 (so 300wpc) and filtered through a an Ashly 2001 active xover.

These are the second OB's I've built (first were Poultygeist's 3-way OB's using Alpha 15 in h-frame and Beta 12A/BG Neo 3) and I have a good number of different drivers (including four more 1808's) that are all good candidates for OB so consider this the first step to more OB madness.

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Cool...thanks for sharing the picture!

The 1808's do seem to relax some over time. Maybe changing over a couple weeks.

A couple questions....do you hear any effect as you go up in levels from the 1808 starting to complain trying to do the LF? Have you tried using a HP on it yet? Running multiples, I really go back and forth at my normally modest levels of advantage/disadvantage of putting any filtering in. And I'm talking only line level, have not wanted, at all, to do it high level.

Also, have you tried the 15's up from the floor boundary at all? Being close to the floor you think an advantage or not? I've also got a pair of those Dipole 15's that I've never taken out of the boxes yet so I've got learning to do on those.

Is the spacing and the openness between the drivers a 'just for now' or a cunningly careful planned maneuver? Drop in another 1808 between maybe to see....?

EV3
 
Thanks guys, but these are 100% "wham, bam, thank you maam" with a few angled cuts to add something that resembles effort. I mean, I didn't even intend to take it beyond cutting holes in the OSB...I was truly just trying to get my feet wet with the Jasper jig.

Ok, maybe I thought about it a little. :scratch2: :thmbsp:
 
evsentry3 said:
A couple questions....do you hear any effect as you go up in levels from the 1808 starting to complain trying to do the LF? Have you tried using a HP on it yet? Running multiples, I really go back and forth at my normally modest levels of advantage/disadvantage of putting any filtering in. And I'm talking only line level, have not wanted, at all, to do it high level.EV3
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Yes, as I pushed the volume up they did start to lose composure as a result of excessive excursion and it occured to me that I need to try moving the xover point up higher and actually limit full range operation for a single. The Dipole 15 is good up to 1K so LOTS of wiggle room there but I doubt I'll have to go over 200 Hz with it....give or take 50 Hz. I'll get a handle on the sonic characteristics of a single then start venturing into multiples.

evsentry3 said:
Also, have you tried the 15's up from the floor boundary at all? Being close to the floor you think an advantage or not? I've also got a pair of those Dipole 15's that I've never taken out of the boxes yet so I've got learning to do on those. EV3
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I tried h-frames with Alpha 15's about five inches off the floor and it killed 'em. I think the quasi-enclosed design benefits from some floor loading.

evsentry3 said:
Is the spacing and the openness between the drivers a 'just for now' or a cunningly careful planned maneuver? Drop in another 1808 between maybe to see....?EV3
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Like I said, "wham, bam, thank you maam". The vertical posts were already cut to 48" so that's where I set the top of the baffle. This puts the bottom of the driver just a little higher than ear level. I sit a little over ten feet away so it put's me just about as off axis in the vertical plane as I prefer to be in the horizontal plane. I like to think the air gap between the subs and main baffle allows more rear wave information to come back into the reverberant sound field around me...which is always a good thing.
 
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I strongly recommend adding a high pass filter to the full range driver. It will protect the driver and clean up the sound by controlling the displacement at low frequencies. Without the crossover you are getting an elevated mid-bass hump due to the overlap of the two drivers which leads to a pleasing for a while sound, but eventually it will sound unbalanced and unnatural. Been there done that.
 
MJKing said:
I strongly recommend adding a high pass filter to the full range driver. It will protect the driver and clean up the sound by controlling the displacement at low frequencies. Without the crossover you are getting an elevated mid-bass hump due to the overlap of the two drivers which leads to a pleasing for a while sound, but eventually it will sound unbalanced and unnatural. Been there done that.
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Agreed. By the end of a one hour listening session the reproduction of content in the second and third octaves started to sound crowded and a little sloppy. With some tracks it wasn't too noticeable, but with others it really stood out.

The Ashly has a "response" control....not exactly sure what it does but it did have a noticeable effect on the LF response with a setting a one extreme having significantly less body and punch than at the other extreme. I just set it somewhere in between and will play with it some more when I have the measurement gear out. Do you have any idea what it's actually controlling?

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From the picture below the knob I would guess it controls the spread between the crossover frequencies, the amount of overlap. But I am only guessing since I have never seen or used and Ashly crossover.
 
Here we go....

Response -
adjusts the damping of the filter affecting
the response shape at the crossover point. The dial
calibrations refer to the amount of attenuation effected
by the filter at the crossover frequency, i.e., a setting
of 3dB means that the filter’s high-pass and low-pass
outputs are each “rolled off 3dB at the crossover
point”. This describes Butterworth filter response, or a
gentle 3dB peak at the crossover point where the two
filter output signals overlap. To obtain a flat signal, or
“Linkwitz-Riley” response, set the Response control to
“6”. To obtain a notch at the crossover point, turn
down the response control past “6” to best suit your
needs. The purpose of this control is to help offset the
inaccuracies inherent in typical loudspeakers, helping
you to achieve a flat system response.
NOTE: The
Response control is not a “slope” control. The
Response control only affects filter response shape in
the immediate vicinity of the crossover frequency; the
ultimate crossover slope is a fixed paramete

I have a feeling that little dial is going to be very useful. :yes:
 
Hot damn!!

Who here will be surprised to hear that by following the advice of MJK I was able to achieve some excellent results?

No one?

That's what I thought.

So last night I ran the signal for the 1808's through the Ashly and started with a crossover frequency of 125 Hz and the payoff was particularly generous. The bottom end gained articulation, weight, tonal clarity, scale....practically every performance characteristic for LF reproduction improved considerably. And of course since the full range driver wasn't being asked to do any heavy lifting it could focus all its energy on reproducing melodic rich and percussive content and it did this marvelously. I still haven't broken out any measuring equipment and my tweaks have been minimal but this combination is extraordinarily promising. I was very engaged track after track and spent much less time noting shortcomings compared to the first listening session. I can say, without hesitation, that initial impressions are that this combination of drivers is in the same league as the the Acoustats, the big JBL's, the big Altecs, the big Infinities....the best I've ever heard. The 1808's still have a touch of upper mid/ lower treble glare, but I have faith that it will diminish as the drivers continue to break in. And there are few other characteristics regarding presentation that I'm going to address with driver positioning but in spite of the few expected developmental hurdles this is becoming a very exciting and productive audio adventure!

I picked up some used Kef LS50's (should be here by the end of the week) to use as a sort of reference for my DIY speaker efforts so before long I'll be able to offer a comparison against what's widely regarded as one of the best little monitors around. Should be interesting.
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Can't wait to hear the comparisons between the OB and the Kef's...both speakers that I'm very interested in!!! I'll be living vicariously through you until then! Heck, I'm also very interested in your other speakers...

Been debating building some OB's for my basement...this thread may end up pushing me over the edge!
 
PastTechFan said:
I did. You SHOULD!!
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Hey, I've been thinking about getting W90's too! I think about getting lots of speakers, lol!

Need to research open baffles more...I get the impression they do better with tubes...what about "tube-like" solid state? Like an old Pioneer SX-535? Ultimately I want to get some proper tubes, but for now, I have the Pioneer in my basement setup. It's going to be open baffles or some vintage speaker down there for now...KLH's, W90's, Bozak...something like that.
 
^^^

Before proceeding with OB's make sure you can satisfy their unique placement requirements...which is at least three feet away from the front wall. If you can check off that box then strap in for one hell of a ride!

I don't think there is anything written in stone or implied wrt OB's needing tubes. OB's are no different than any other speaker in that whether or not it will benefit from tube power or SS is gonna' be case by case. For instance, my first (and only other) OB project used the Eminence Beta 12 and I tried it with a restored ST-70 and Soundcraftsmen MA5002 and preferred the MA5002 by a fairly large margin.
 
If you use my OB recipe (Alpha 15A + full range driver and a passive crossover in the 200 Hz region), tube amps have been known to struggle. I have tried it and others have reported back that the tube amps do not like the low crossover frequency, the bass output is significantly compromised. Stick with a SS amp in this style of passive OB configuration.
 
Interesting...

tomlinmgt said:
...I like to think the air gap between the subs and main baffle allows more rear wave information to come back into the reverberant sound field around me...which is always a good thing.
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I would have thought the open space between drivers might lead to some "cancellation" effect. Not saying that is a bad thing.

You're positioned only 10' away? I would have thought further judging by the size of the drivers.

One day I have build some OB speakers. Sounds like a fun project. Problem for me is where to place them.
 
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