chops

This is what I have come up with. Also, according to the calculator in this link, the F0 should be 66Hz for my room... However, when I put 66Hz into the Linkwitz transform, it says that my sub is down -3dB at 14.69Hz! [*-)][8-)] Everything between both the blue and yellow are identical except for the F0. http://www.sengpielaudio.com/calculator-wavelength.htm

Understood about the room gain setting. The 10dB at 20Hz thing I'll have to play around with to figure out exactly what you're talking about. All I have to take measurements with anymore is my old Rat Shack spl meter. I'll have to dig up that correction guide for it so the readings will be somewhat accurate. As far as music, most of it is pipe organ, most of which are pipe organs that are capable of 16Hz at Low CCC, and a couple that are capable of 8Hz. However, some of the recordings pick up the sound of the tremolo, which depending on it's speed will produce a beat somewhere between 10-15Hz. I also have a couple of test CDs (Chesky, Stereophile, Telarc) that I can try, one of which has a signal all the way down to 5Hz. As for making waterfall plots of any of these, I have no way of doing that. I wish I did though. Is there any free software out there that can do this? "I'm just saying that it's struggling at the lower frequencies (much less control) and that there are some psychoacoustics involved that make room gain seem unnatural" I wouldn't say that the sub is struggling, especially being the fact that even at the loudest levels, I'm only pushing about 50 watts into the sub, and I can visually see the drivers moving only about a .25" MAX, which that's down around 16-20Hz. That's only about 8mm, and if I remember correctly, these subs can handle 15mm x-max. And true, I may be wrong about this sub going as low as I think, but I'm sure happy with it. It is definately cleaner, tighter, quicker, more accurate and hits harder than the SVS PB12-ISD/2 did. At any rate, this sub is leaving a smile on my face.

Cool. Thanks! I do have a few questions... So when you entered my sub's information, you did it as a 6.3 cu.ft. enclosure with 2 Dayton drivers, right? (I just want to make sure I'm doing it right on my computer) Depending on how well sealed the room is, do I go higher or lower from 10-30Hz? IOW, if my room isn't very sealed at all, do I go towards 30Hz more or 10Hz? And what did you mean by "Whatever results in 10dB at 20Hz"? Do you think that the hallway in the right rear corner of my room in anyway influences the "F0" at all? The reason I ask that last question is because this sub is putting out some seriously low bass below 16Hz to the point that you ONLY feel it and hear various things around the house oscillating at unknown frequencies. [] Thanks again!

DrWho, which version of WinISD are you using? I have the Pro version and am trying to figure out how you got the room gain?

Nope... it can be done both ways... as long as they share the same hole. In other words, you'll have to plug one hole... and install the two drivers in the other (in your case, face to face is the only way they'll fit) ROb Rob, You are referring to an isobaric configuration, not push-pull. However, according to DrWho, what I have is still not push-pull. That, I don't understand. [:|] BTW, I now have one driver physically inverted.

So what you are saying is that for me to have a "true" push-pull configuration, one driver has to physically be inverted? I hope so anyway because I'm in the middle of inverting one of them right now! LOL Anyway, my room is 13x17 with an 8' ceiling. There is a hallway opening in the right rear corner of the room, probably about 25' long. (if that helps at all) []

Okay, you guys are starting to comfuse me. LOL So you are saying that I have it where both drivers are working against eachother, both pushing in towards eachother then away from eachother? I think it's supposed to be as if both woofers are physically attached to eachother, and move in unison. [:^)]

Yes, both drivers are mounted facing away from eachother. As far as some bass being cancelled between the one phase inverted driver and the K-33 in the CW, I don't know if that's an issue or not. They are both crossed over at 50Hz, so... This is what you're talking about, correct? Here's a couple pics showing both sides...

Thanks for the pics Mark. I hope you didn't go out of your way to take those pictures just for me.

No problem. BTW, it doesn't shoot mellons, but it does a great job of smashing them! LOL

The sub is crossed over at 50Hz via the subwoofer output on my Pioneer Elite receiver. I'm not sure if it's a 16, 24, or 36dB crossover or not though. A passive radiator is nothing more than a tuned port, without actually being a vent. The drivers are in fact out of phase being that they face away from eachother. At the very bottom of this page, it gives you a good explination of the push-pull concept. This has been the design choice of M&K subs for years, since 1989 with the introduction of the MX 2000... http://www.danmarx.org/audioinnovation/theories.html http://www.mksound.com/timeline.htm

As Michael stated, they all used the K-33 woofer. However, I was told that all the pre-1985 K-33 were the only ones that met PWK's specs and the ones post-1985 did not. Also, eventhough some of the Heresys and Cornwalls used the same K-55V and K77, the squawker horn itself was different. (K-600 vs K-700) BTW, forum member BEC sells both the K-33 (post-1985) and his own CT1526 woofer which is custom made to PWK's pre-1985 specs by Eminence.

LOL Come on people, let's not crap up this thread now. And to answer your question jacksonbart, I am quite capable of multitasking. Please, let's stay on topic.

The drivers have dual 8 ohm coils. I wired the VCs in parallel for 4 ohms per driver total. I am powering each driver with one channel of the amp. It's a 2-channel amp, one driver per channel.

Sat night, 9pm: So I decided to do something with the two spare Dayton 15DVC drivers I had sitting around (1 used, 1 new), so I built a push-pull subwoofer to save space and still get max output and extension. After driver and brace displacement, I'm guessing it's about 6.3 cu.ft. sealed from it's original 6.59 cu.ft. It's a 24" cube. It's not the prettiest thing, but certainly sounds darn good! Sun, 1pm: So once I figured out what I was doing for a sub, I went up to Lowes with my "other" brother and his SUV to get the 4x8 sheet of .75" MDF and have it cut there to my specs. I'm just tired of building all of my projects with a stinkin' jig saw all the time, hence why I had them do the cutting. I was expecting to pay $30 or so for the wood and cuts. The MDF was $20 and there were about 7 or 8 cuts @ $.50 each. The guy that was helping me was the department manager. He was a little light in his loafers too, if you know what I mean, but he was pretty cool and funny as hell. Anyway, he said he hadn't used that vertical saw in a while, and he made a couple of mistakes, being about an 1/8" off on a couple of cuts. So he ended up giving me the 4x8 sheet and all the cuts, plus corrected the cuts for a grand total of $10!! All because he appreciated us being so patient with him! 2pm: We get back home and I start measuring out the voids to cut out of the brace and the driver motorboards. I then ask my brother jt1stcav to give me a hand in cutting and assembling the cabinet. 6pm: After a lot of drilling and screwing and siliconing, and lunch break, I wire up and install the drivers (both VCs wired in parallel for 4 ohms on each driver) and connect them to the amp. Between 6-8pm, I clean up everything, eat dinner, play several different choice CDs, then setting down around 8:30 or so for a movie... AEon Flux According to one of the guys on the DIY Audio forum, he says that my sub should have a Qtc of about 1.0 and an F3 of 30Hz via BassBox software. Then when you consider the room gain (which comes on strong in my room below 30Hz), I'm getting solid clean output well below 16Hz. Efficiency is another amazing thing about this sub. With moderate volume levels, the amp is only reading between 0.5 and 1 watt! When I'm really cranking the volume with some of my CDs or in the movie last night, the meter only reached 30 watts and peaked 50 watts once or twice, and it was loud as heck in here. Louder than I would normally ever play my system. I would really love to know what the actual efficiency of this sub is. I'm thinking that it's maybe up there around 100dB or so. The amp I'm using is an old Technics SU-8099 integrated that was bought back in 1979 with the Cornwalls new. It's rated at 115W @ 8 ohms per ch and 180W @ 4 ohms per. I have the drivers wired to a 4 ohm load to each channel of the amp and have the sub line-out on my receiver going into the "Main In" on the SU-8099 which bypasses ALL tone and volume controls. Right now, it is nothing more than just a two-channel amp. Plus its freq resp is rated down to DC (0Hz) for the first 5 watts or so! I was thinking about getting a Samson Servo 600 amp to put 600 watts into this sub, but now I'm not sure I even need it. And I think I can safely say that this sub outperforms my old SVS PB12-ISD/2 that I used to have, even when tuned to its 16Hz setting. I know this thread should probably be in the "Subwoofer" section of the forum, but with all the stuff going on down there right now, I'd rather not have to go there. So with that all out of the way, on with a few pictures... of course! []

Ah... So the K-33 must be rolled off a little early instead of being allowed to run all the way out like on the Type B. Thanks fritz.

I don't know, but I'm kind of thinking that maybe that 20uF is for the woofer. Not sure though. And thanks for the kind words. What can I say, I like takong pics of my mods. []

Once you sit and listen for a while with the new caps, you'll find a bunch of things you didn't hear before. [] BTW, what exactly on the B2 network takes 20uF?! That network must be quite a bit different from the stock Type B. [:^)] And yes, I can't wait to see the pics. []

Yeah, the two of us are brothers, but you're more of an idiot than I thought if you think one of us are logging on as someone else. LOL Heck, maybe because you thought of it, maybe YOU are the one logging on as Puz. You both DID join right around the same time here. Hmm... Imagine that! BTW, YOU'RE the one making a fool of himself. FOOL!

Look, I don't know or care who you are. For one thing, you are some jack@$$ that has just started on this forum, and I WILL NOT put up with your crap, especially when it comes to using MY FULL NAME on the forum all the time, and making fun of or making nicknames of MY NAME! I don't let my family or friends call me nicknames, and I'm sure as heck not going to let you do it! So cut the crap now before I take it up with the moderators!

Umm.... What in the world are you talking about, man?! Most of Bose is manufactured in Mexico, not Guatemala. Sounds like someone has gotten ahold of some bad ditch-weed. You know, ganja... monn.

If you're concerned about the sub pressurizing the PR on the II's, don't worry about it. The sub would have to overload the entire room before effecting the PRs. Plus the fact the II's own woofer is going to have a lot more influence on the PR than an outside source will (a.k.a. - the sub) []

It's a shame you didn't fire up the 901s. It would have been interesting.

For some reason, I don't think false corners work for traditional loudspeaker designs as they need the actual room boudaries to reinforce the bass output. Khorns are different in that respect as the false corners act as extensions of the folded bass horn itself. However, I could be somewhat wrong. I'm sure someone else will chime in soon.

Oddly enough, I didn't see any Klipsch of any kind there. However, I am very interested to see what you all had to say about the Bose 901's compared to the other speakers in the room. Who's were those anyway? (I'll understand if you rather not say) [] Looked like a nice gathering. Lots of neat equipment too! Charles