Crossover design for subwoofer with Orca speakers

[docbob52]

i need help designing a crossover for a bucket sub to use with my cherished Orca speakers.  The sub bucket http://www.transcendentsound.com/Transcendent/Subwoofer.html came from Ed Schilling of the Horn Shop   http://thehornshoppeforum.com/index.php?topic=406.0

Rather than buy a plate amp like the Crown XLS I plan on using my Nuforce Reference 9s.  I think that the crossover needs to be a band pass with a cut off of 12 and ideally 24db.

I am a total newbie to crossover design and so all help appreciated.

[Paul Joppa]

If you look up the speaker parameters

http://www.parts-express.com/peerless-830667-8-paper-cone-sls-subwoofer--264-1102?utm_source=google&utm_medium=cpc&utm_campaign=G_MFG_OPQ_Products_Exact&utm_group=264-1102_E_F50-100

you will see the bucket is very close to the "optimum sealed box", which has a -3dB point of 58Hz and a 12dB/octave rolloff below that frequency. Room gain will boost that giving greater in-room extension - if you have the right room.

Hopefully Clark will see this and give some guidance on sub crossovers - what frequency, whether to high-pass the Orcas, etc.

[docbob52]

Paul,

Clark crosses over his Dungeness sub at 75 Hz and he and uses a lowpass filter to the sub which derives it's input from a speaker level line.  The Orca's receive the full audio spectrum from the amp.  The Dungeness sounds great (I have one here) so I thought it would be fun to experiment with  the bucket sub, which should work in a similar fashion.

Yes the Bucket sub works best with a minimum 12 dB/octave low pass filter and best with a 24db/octave low pass filter so it looks like this is going to be a 3d or 4th order filter.

I would like to design the filter as a variable one to use with different speakers also.

[BNAL]

docbob52,

I was looking at this sub as well. I'm running my Orcas with a pair of inexpensive Yamaha subs (YST-SW215) that I used for my S.E.X.y speakers. they have served me good, but want to try something different.

I can't wait to hear what you think of the sub with Orcas.

[Clark B.]

Hi guys!

Ok...Now I really have to step in here and poke some fun.  A "redneck bucket sub?"  The description mentions Bible passages mixed in with 4:20 references?  Umm. ok?  My BS-o-meter is pegged at "11" 

Yet every time you point a finger there are 4 pointing back...(and anyone who knows me personally knows that I do "get the joke" of the bucket sub.)

  I happen to make "Thrashers."  They sound fantastic.  Now, I can't make your decisions for you, but please folks, use the bucket sub with Thrashers, not Orcas...

http://www.blumensteinaudio.com/on-sale/

As a total counterpoint to the price point of the bucket sub experiment, recently I upgraded our system to "Deluxe Dungeness" with the same 25 watt Dayton amp but built with all 3/4 inch chocolate bamboo in my reference Deluxe Orca system (driven by Paramounts) and I did notice a slight benefit to transients, bass size, and overall "disappearing act" of either a single or a pair of this 3/4in sub construction.  Now we are only talking about a roughly 5-10% "total" improvement (which is still very important to me as a designer.). Still though, along with several other improvements to the demo rig lately, and more to come, the deluxe demo system we are running right now is something we are really proud of.  Its been sounding really and truly musical lately.

The recent improvement with Deluxe was attained without any gain, tuning, or crossover changes from the normal Dungeness.  And of course there won't be a measurable difference, and I'm cool with that.  Considering how refined the construction and materials quality of a 1/2 inch dungeness already is, I was surprised to hear ANY benefit from the thicker/different cabinet wood.  Yet, aesthetically, the sound difference is there. 

 There's no way I'll be able to measure it other than to tell you to knock (with your hand) the 1/2 inch Dungeness cabinet, and then knock the 3/4inch Dungeness cabinet and you'll hear a little less resonance and different character of resonance with the Deluxe construction.  And it costs more money. 

I actually used to make a subwoofer for an older model of Orcas which used the same 8" peerless woofer Ed mentioned for the bucket sub.  Its a pretty good driver.  I tried that driver in both sealed and BR and greatly prefer the BR.  Ultimately I went for something that is a little more "chill" sounding which is the 6.5 inch woofer we are using now.  That 8" peerless ultimately sounded a little out of control down into the ultra lows to my ears, or just something not quite right but hard to put my finger on.  It might have been a problem with the cabinets I was trying it in.  Maybe I should have had the thing in a bucket?  Who knows?

Still, my answer for someone seeking more dynamics from the bass augmentation of their Orcas would probably be (as you might guess) multiple Dungeness.   We have folks sending in RTA's of their systems in room w/ single or double Dungeness showing that they are very well behaved in real rooms down into the mid 30's and that psyco-acoustically it all integrates well in either carpeted or hardwood environments.

But back to te topic of a DIY big subs - I'd recommend a pretty wide range of X/O's to experiment with - anywhere between 75-90hz (depending upon the subwoofer and X/O slope).  In terms of X/O slope range, anything between 12 and 48db could be the ticket.  It all depends on the driver and cabinet character.  I do prefer plate amps for my production models because they are cheap and easy to adjust and sound great if you get the right one for your system. 

Other subs?  The Dayton Audio reference 8" is a good driver.  As is the Eminence Lab 12.  Both need large cabinets.  the Fostex 8" woofer is also good and I've built a few.  those get down to the 20's.  Very expensive driver, and a long lead time though.  It was not as transparent/integrated as the 6.5 we are using now, and it just had unnecessary frequency response for most peoples' systems.  But that's what DIY is for, right?

Once I tried 4- 15" woofers with the Orcas.  This was nice, very natural and dynamic, but the low frequency cutoff began around 60 hz which just wasn't low enough, and the stiff suspension systems in the pro audio drivers I was using didn't "wake up" at the same time that the Orcas did, volume wise.  So I tweaked everything out to line up at the Orcas' maximum volume capability with the Paramounts.  This ended up being pretty nice overall, but again, still just didn't go low enough.  Over time, I've concluded that I really need my bass to go down honestly into the mid 30's or I just can't connect with the music the way I want to. 

Some of the best bass I've heard with the Orcas was hooking them up in my buddy Pete Riggle's room.  The Orcas were standing in the place of his 3 way horn system which normally goes down to around 100hz.   Those typically then get augmented by a true -3db at 20hz,  30 ft long horn loaded subwoofer (with a mouth so big you could drive a car into it).   We adjusted the sub for the phase of the Orcas and then after about 10 minutes of delicately adjusting gain and crossover frequency, wowee!  It really worked.  Very surprising that it mated so well.  Super subtle yet powerful.  If you've got the space in your attic...this system did pipe organ like you wouldn't believe.

Now if you really wanted to go crazy, then just get a DEQ-X or equivalent.  You can tailor the system with infinite precision.  A really good digital EQ and X/O, I don't care what anyone says, is both expensive and transparent.  Dan's mega system on the other hand uses gentler slope tube crossovers and these also sound very nice indeed.  Overall I might prefer the tube X/O's because...well, I dunno.  YMMV.

Yesterday I had a local pickup of a deluxe center channel pair/double dungeness order from the shop.  This was the first Deluxe CC/double Dungeness system I'd heard in a while and it was better than I'd remembered.  We have another order like this to send out next week and then I'll be making a system just like it for our demo space.

Overall, I guess my message is that if one is looking to out-perform the Dungeness, it might be wise to either purchase multiples, or just take a much higher end approach entirely.

(and on another note...man, the bucket sub totally cracked me up!  Took me right back to my warm and fuzzy memories of college daze of audio DIYing. Thanks for posting!)

Cheers!

-Clark

[2wo]

They actually sound pretty good...John

[xcortes]

In my experience the quality of the "sub" amp is also very important. I use Karlsons modified with the Tucker recipe from Sound Practices under my horns. Crossed at 80hz 4th order. The crossover is a Marchand passive driven by a MQed Sex amp. For some time the best bass was a McIntosh Mc275. But the champion is a Bedini 25. I guess class A has it's benefits. Of course not many SWs can be run with a 25 watt amp.

For some time I tried the Ks under my WE 755s and the blend was superb.

The second order clark mentioned of CT orcas plus Dungeness is mine. Will play in my office from a Willy Herman Nak Dragon through a pair of Co opt Paramour 2s (or if ever get them back from my friend a pair of SR45s).

[Clark B.]

They actually sound pretty good...John

For sure, John...i'm sure they do. That's why I recommend pairing the bucket sub with the thrashers, which also sound pretty good, if you dont care for looks. The Thrasher is a Bofu clone, btw.

[Doc B.]

I think the concept is cool. The first thing that popped into my head - right after a memory of this super cute girl I used to work with in the food business bending over one of those pickle buckets while wearing these really short shorts - was how those buckets make great drums for street musicians. Not sure if that kind of resonance is a great idea for a speaker cabinet, but I still like the concept as a super low budget quick and dirty project. Might be a great mate to the cardboard box speakers that were demoed at the Mid Atlantic Bottlehead meet.

All that said, after a few weeks with the Blumenstein gear in new HT I have to say that the Orcas and the Dungeness subs work exceptionally well together.

[Clark B.]

how those buckets make great drums for street musicians. Not sure if that kind of resonance is a great idea for a speaker cabinet, but I still like the concept as a super low budget quick and dirty project.

Dan, you definitely have a point there in regards to it being a drum.

I was noodling on this design last night after my best friend's birthday dinner.  He finally got a set of Orcas for which he and his fiance were very appreciative.

-----

Ok, so let me disect the bucket design - the bottom is filled with concrete.  This is good.  The cylinder of the bucket, I bet, is decent at resisting resonance.  This is what people are hearing and liking no doubt (other than the driver which is pretty good).  Yet the thin walls of the bucket are still going to wobble.  just knock around on them.  In many buckets the cylindrical layer of plastic is not perfectly even in thickness either.  This will lead to different buckets sounding different from one another(?)  Or just that the energy will dance around along the walls of the bucket in a chaotic manner.  For spherical/cylindrical stiffness to work best, irrespective of material, its got to be a good sphere/cylinder.  Like blowing bubble gum it will pop at the thinnest point.

Similarly, the top of the bucket is just the driver mounted into the thin walled plastic bottom of the bucket.  This is probably more of a problem.  The "circular plane" of plastic doesn't have the benefit of being a hemi-spherical end (like a scuba diving cylinder).  So it behaves just like a plane to resonances.  Not good when only 1/8th inch thick plastic.  but luckily - its not a huge area.

So I have some suggestions/addendums to this "cabinet design" if I can go out on a limb and call it that

Step 1: 

Epoxy a stack of multiple buckets together, using a rubber mallet to pound the stack together tightly.   

Step 2: 

Then cut the whole thing down flush to the bottom of the first bucket.  (using a sawzall to do the cut).  The multiple buckets stacked together would truly amplify the strength of the walls, and give "ribs" like a wine barrel via the multiple "projections" of the buckets in regular intervals down the outside cylinder walls.  Its like an exoskeleton.

Step 3:

The thin plastic bottom of the original bucket has got to be reinforced now in order to match up with the improvement to the cylinder wall stiffness.

---Step 3 Method 1.  In my mind, I am thinking that it would be possible to flatten the cut (gigantic piece of sandpaper?)  (Handplane and test?) (laser cutter?) but in either case just to use some method so that it would mate up decently with a flat piece of wood.

An exterior 1.5 inch (double stacked 3/4 of course) wood baffle is then epoxied or siliconed (if the juncture is rough)  and then 2.5 inch drywall screwed to the cylinder wall (end of the bucket).  So in that case, most of the bottom plate of the bucket could get cut off to make way for this new baffle.

The added wall thickness from multiple buckets stacked edgewise would probably give enough meat for the screws to get an inch or so into the cylinder wall without problems.  Countersinking and oversizing the holes that go through the wood baffle would facilitate a clamping effect with these screws down onto the baffle for a stronger junction.  This juncture could be stiffened via this method pretty handily. 

---Step 3 Method 2. Or alternatively, you could just inset a circular (enough) wood panel onto the bottom of the bucket (after chiseling off the plastic tabs) and epoxy the crap out of that juncture.  Then the whole thing would get sawn into for the driver hole.  Or stacked upon with another layer of baffle for extra stiffness.

----

Ed was saying that he's happy enough with silicone alone (without screws) to seal the driver to the bottom of the single thickness bucket.  Either of these measures would assuredly be an improvement.

And if those added measures don't help the sound, then who cares?  Its just a bucket with concrete, right?  So it might only take a few extra buckets and a piece of scrap wood to potentially improve it.

---

My only request to go along with this ammended DIY design, should you find it to be successful, is to mate your mega buckets, if you can afford it, with a pair of our Thrashers.  We've only sold 4 pair this year and 3 of them were to the same old suspects (local business owners) who already own several pair and know how awesome they are...  They are so fun!

P.S.  Oh - and I have one more request - Please keep your Orca systems pretty.  Our team puts alot of effort in taking these 3" and 6.5" paper cones and turning them into the wild animals of speakers they are.  After 7 years in business, we've found that our most effective form of "advertising" proves time and again to be through the traditional channels - friends and friends of friends of our hundreds of customers noticing how practical, pretty, and awesome sounding an Orcas systems is.  And then finally taking the plunge themselves weeks or years after first laying eyes on them.  HiFi like this needs to be brought back into the Home.  Life.  Family.  In myriad ways, its up to all of us to take pride in and proliferate truly good design.

So there's a sunday soap box/bucket

Cheers,

Clark

[docbob52]

Wow! Looks like I generated some interesting discussion in my original post. I created some confusion as I neglected to say that I already have a Dungeness sub here which I am absolutely nuts about.  It integrates seamlessly with the Orcas unlike no other sub I have ever heard and no matter where I locate it   I seriously doubt that it will leave my system unless it is stolen.  Needless to say,  I put my HSU sub in storage until I eBay it or if someone wants to buy it.

My interest in the Bucket sub was for several reasons:  It is dirt cheap, easy and fun to build.   I planned on evaluating the Bucket with my Orcas, Paramounts, and BeePre (a system I love) before putting in in a budget system for for my shop.  If I  don't like it, then we have lots of Rednecks here in Alabama just dying to have it in their pickup trucks or living room.

Thanks xcortes for the great idea about the Marchand passive crossover.  The XM1 ME board looks like it could do the job for cheap but requires manual interchanging of the resistors to change the cross over frequency.  I will keep looking for a design I could build myself or a suitable calculator to design and build a 3d or 4th order passive crossover that is variable.

Again all help appreciated.

[BNAL]

Clark,

The idea for me of building a bucket sub is in the DIY aspect of this hobby and not that the sub would sound better then the Dungeness. Based on my experience owning the Orcas and enjoying the beautiful music they convey is that the Dungeness would mate perfectly with them, since I have not heard them.

Also, there is no way that a 5 gal paint bucket could ever compare visually to the beautiful cabinets you make. I think that I would only be able to bring the buckets out in the middle of the night when everyone else was asleep. LOL and true.

Brad 

[Clark B.]

The XM1 ME board looks like it could do the job for cheap but requires manual interchanging of the resistors to change the cross over frequency. 

Again all help appreciated.

Thanks for the kind words!

I do want to make sure you guys caught my dry humor in the first response though.  I had to veto both the other members of the shop this spring to rerelease the Thrasher.  I'm the only person really building the things.  But I'm an advocate of there being "sound only" (no looks) large format solutions like these...  Who knows maybe I'll give the beefy bucket I laid out in my previous post a shot sometime.

The manual resistor change could be considered a feature.  It seems inconvinient at first, but may be the best connection quality (?) in either case, I think the reason I prefer Dan's tube X/O is that its hard wired and tube.  Once you find the right spot, it will stay that way for a long time, so keeping knobs away can be a good thing, practicality speaking.

As a suitable compromise, I remember a pass labs crossover I helped set up in one of Terry Cain's RMAF systems. It used switches underneath a cover.  It took some fiddling to get right, but worked out well.  It drove extremely well broken in double ben ES fed by electronluv 45 amps running EML 45's and stereo baileys driven by a berning Z270 OTL amp (IIRC).  This worked quite well.  I was the impressionable age of 23 and it certainly made an impression . The crossover point of that system was 75hz...


Brad: right on about the middle of the night system.  The AC sounds best then anyways.  I've recently been experimenting with ac filtration and a variac running 120 volts has been an improvement as its essentially a balancing transformer at that point.

You could carpet your bucket sub for looks and it would be a dual purpose cat scratcher/room acoustic damping cylinder.

[Paul Joppa]

Hey Clark - in a quick look at the web site, I don't see the Thrasher listed. You might sell more if customers knew it was available ... just sayin'  :^)

Seriously, last I saw it had shrunk from 2-3 cubic feet to about 1 - unless I mistook the post. Yeah, I read a lot of posts too quickly! Anyhow, I'm asking for some details.

[Natural Sound]

Hey Clark - in a quick look at the web site, I don't see the Thrasher listed. You might sell more if customers knew it was available ... just sayin'  :^)

Seriously, last I saw it had shrunk from 2-3 cubic feet to about 1 - unless I mistook the post. Yeah, I read a lot of posts too quickly! Anyhow, I'm asking for some details.

Clark posted a link above.http://www.blumensteinaudio.com/on-sale/