[gerG]

Fair warning: this conspicuously inconcise assemblage of verbosity contains ultra low frequency information which may result in an inexplicable craving for even more audio gear (but honey, we really neeeeed another electronic crossover to complete the system). It is another long winded gerGtome best tolerated with a good single malt and some great jazz. At least, that is how I wrote it

As some of you have no doubt noticed, I am rather fascinated with deep bass response. I have been building subwoofer/satellite systems as a hobby since it became logical to me to build a pair of 8" Phillips woofers into the back of my 69 Dodge Super Bee with a hand made x-over to augment a pair of "fake ads 200" speakers. This affront to the gods of horsepower occurred back in 1980. Unfortunately I was years ahead of the trend, and my friends just thought I was nuts. Actually they thought that for other reasons, and this just sort of fit the pattern. I was never part of the boom-boom crowd. I was after that elusive quality of realism that I have yet to achieve.

Somewhere along the line I decided that a system using "full range" speakers crossed over to some serious infra-woofers at around 50 hz would be very dynamic, accurate, and giggles galore. I set a goal of a sub that would do 110db (each, muahahaha...ahem) at 20 hz with low distortion levels. I don't know which of my scotch adulterated brain cells came up with this target, but it ain't easy! Nevertheless, my recent outdoor project subwoofers were designed to meet this goal. 10 cubic foot monsters using 16" cast frame JBL woofers in a wrapped bandpass layout (I will explain that one on another day, with photos even). I originally designed them with 2 6" ID (3 ft long) ports. Due to the twin tubes I dubbed them the "shotgun subs". I later changed the design and used an integral rectangular duct. No problem: I dropped the t and now I have the "Shoguns". Btw, can there be 2 shoguns?

I built the prototypes out of a material called multi-core. 13 ply Baltic birch was my first choice, but it only comes in 5x5 sheets, and dumb-dumb me laid out the cuts assuming a 4x8 sheet. The multi-core was a mistake. It likes to warp, but steadfastly refuses to un-warp. What a pain in the ass to assemble! It is also not quite as tough as high grade plywood. Nice maple veneer, but ugly edges. I had intended to bondo the edges, radius all corners, and spray them with gloss white urethane. Great for outdoor duty.

These beasties are big: 18"x24"x50". They are not very heavy, but no way can I move one by myself. A hand truck is required. Filled with anticipation I set them up with some small satellites in my outdoor system. Not very impressive. They go deep as hell (and then some) but lacked any sort of punch. Theoretical response is +/- 1 db from 20 hz to 70 hz. They drop like a rock on either side of the bandpass. (That is, if a rock drops at 24 db/octave). I was pissed off and was all set to convert them to a bass reflex, but I decided to drag them indoors and hook them up with my video system just for fun. Mains in this system are a pair of ADS 1290s. Beautiful slender tower using 2 very well made 8" woofers, 2" dome mid, and 3/4" tweeter. Dynamic as hell, with great imaging. I am convinced that ADS (formerly Braun) was about 10 years ahead of the rest of the US manufacturers. My video system currently has a Yamaha DSP-A2070 integrated amp, ADS active x-over, and an HK 870 amp to work the subs. What the hell, it's only my video system. Oh yeah, and my most important piece of audio gear: a gorgeous Ekornes Mobilo II chair! Why should my ears have all the fun? If you don't have one of these yet, get one!

I stood the shoguns up in the front corners of the room, which orients (subtle pun) the ducts downfiring about 2' from the side walls. The result is astounding. I have never heard bass response like this. Tight, controlled, quite punchy, and deeper than I can hear. My Richter Scale reads flat response down to 30, then a gradual increase to +3db at 20 with no equalization. Weeeeeeeeeeeeeeeee! I began by listening to some jazz which was recorded with a wide dynamic range (Flim and the BBs). The percussion was especially amazing in it's realism. I eventually worked my way up to the Telarc recording of the 1812 overture for a very inspiring listen. The cannon shots were making me flinch. Kind of like firing a 44 mag. What fun. I am not even close to pushing the capabilities of this setup, and it is frightening me.

Now, here is the punch line (not so subtle pun). Several days later when I was getting up to get ready for work, I heard water running. Very faint, like a faucet just slightly open in the other end of the house. Some investigative listening, and later confirmation by a leak detection service, indicated that I have a broken water line under the concrete pad of my house. An interesting coincidence, don't you think? Never mind the fact that I can actually feel low frequency vibrations through the concrete when I play this system.

There is probably a moral to this story, but I choose to ignore it. Keiko just got tired of shaking the earth. Time for some Tom Scott!


Adios audios

gerG

 

[raymondlin]

You broke your mains water pipe with your woofer? well done, I think that's a first! and one of the reason why I smiles when I see people with huges bass tubes in their cars and playing at loud volumn, I can see it in my head that the car actually falling apart on the streets while they are driving it.

Well done on the speakers though.

 

[legoman]

If that episode isn't worth a custom title, I don't know what is. How much more inspiration do you need. Shame, that Jude is so busy these days. Maybe we should alert him to this thread in a few months, when there is less stress

 

[grinch]

that is one of the most enjoyable threads i have ever read. i even printed this one out to show to co-workers. thanks for the good time.

 

[Budgie]

Do you by chance remember which JBL driver you used. Just curious- My sub uses a 2235H if I remember correct.

 

[gerG]

Glad you guys enjoyed it. I had the opposite of writers block that night, and just had to let loose with something non-work related.

Budgie, the woofers are GTx-15, I think. They are a hell-stout car sub which just happened to have the right characteristics for a bandpass configuration (albeit a big one). There are a couple of 12" units out there with similar cahracteristics which would give similar response in a smaller package. The tradeoff would be max spl, which I don't really need indoors. I got the GTx-15s from Damark for $100 each back in 98, and they have been laying around on the project shelf since. I have 4 total, so I will have to come up with something else (eee hee hee). The 12" drivers that I like are the NHT that Madisound sells, and the Titan 12 that Parts Express carries.

Ray, I can't be sure that the sub broke the water line, so please don't tell my insurance company. The neat thing about this system is that it doesn't resonate things. If somehing in that room vibrates I find a way to damp it. No boom or overhang. Just deep, solid bass. I am still agog at those cannon shots.

Upgrades to the system are in process. Expect an update next week.


gerG

 

[setmenu]

Fantastic!!
Reminds me of a device a friend wanted to build called a 'pile driver'.
Great big posts set into the ground/foudations with huge solenoids driving a steel weight up and down onto the post to
great that earthquake effect!!
His main worry[only worry!!] was that they would be driven further and further into the ground and eventualy disapear

He never did build them

Setmenu

 

[ai0tron]

Yeah blowing up your water mains deserves a merit badge or something.

 

[gloco]

LOL, can you post some pics of the subs, i'm curious to see what they look like.

 

[gerG]

I know I know, I owe you guys some pictures. I will get to it. I am a bit embarrassed by the appearance of these subs. Since they were prototypes for outdoor duty I had only intended to radius corners and spray them gloss white. Unfortunately I dragged them into the house, stood them in the corners, and there they set in all of their naked glory. Yech, I can do better work than this. Fortunately a panel of Auralex studio foam just fits the side! I am thinking foam covering and a granite top to reduce cabinet vibes, all done <brushes hands together in jesture of dismissal>

Since last report I dragged in a 4 channel electronic crossover, an HK pre-amp, a Carver 6 channel amp, and the Sony 333ES. Running the ADS biamped, and crossing over to the Shoguns at 60 hz. The system is becoming quite liquid. The room is next. I procured 2 cases of Auralex foam, and experimented last weekend. I need some advice on this one. I have never been able to tune a room to my satisfaction. Any boundary reflections just seem to add a noise floor. I will draw up the room and send it to Auralex to see what they have to say. Anybody had any success here? I don't want to do anything too permanent because I am going to owe my wife a new house when she figures out how far I intend to go with what used to be the living room. I did promise to get the rear projection TV out of there. I think that was sufficient warning that I am shopping for a front projection set-up, don't you?

Oh, off the record, I now have 2 broken water lines. Damn that Tchaikovsky!


gerG

 

[Dusty Chalk]

And here I was, just thinking that this story couldn't get any better...

 

[gerG]

Hear we go again!

Sorry to drop out of touch on you guys! An awful lot is going on in my cubic foot of the universe. I really need to find out what the hell they gave me prior to the surgery. I tried like crazy to remember what was going on, but there is absolutely no perception of time passing. Is that cool or what?

But never mind that, because music matters more! I came home this evening after a wasted day (presenting to the next couple of levels of management) intent on relaxing. Music and Bourbon (not necessarily in that order) were on the agenda. I rummaged through the headphones , but I was not able to go with the first choice (AKG K-1000 + PB1500 subwoofer + reading chair) because I have that combo set up in the corner of the bedroom, and my poor wife is trying to escape a migraine.

Option 2 was employed: my main indoor system with the Shoguns! Oh yeah, and my favorite chair. Unfortunately I didn't get too far into a CD before my old H&K 870 preamp started cutting out on the left channel. It is time to tear it down and clean the damned pots again. Fwiw I also have an even older 770, and it needs the same kind of care from time to time. Since I was already pissed off, and (more significantly) on my third bourbon, I shut down the kilowatt amp, pulled the x-over input cable out of the 870, and plugged it straight into the Sony 333 CD player. Is this a recipe for indoor fireworks or what? There is no way in hell that I would have tried this in a more rational state of mind. I mean, how would on know what volume levels would result? Have you ever tried to buy an ADS Cobalt tweeter? I have, and it is not a pretty process!

Fortunately, rational thought was not an impediment. Although I was risking launching 2 tweeter domes across the room to impinge on the distant back wall like a couple of toy suction darts (remember those?) the result was sensational! Ok, it was also kind of loud, but not unreasonable. The volume level was very realistic. I was listening to Keiko Matsui's "Whisper from the Mirror" at the time. This recording has some serious LF content, which the Shoguns translated into plate tectonics of course (I will check for broken water lines tomorrow). The neat part was the increment in realism. It was yet another layer of veils removed from between myself and the recording artist.

It is a very strange sensation, not being able to tweak the volume control. Sort of like a live performance in a way. On the other hand, the volume was just about perfect if I were listening without consideration for anything else going on in the world. I have no idea where this revelation will lead, but I am visualizing 6 or 8 mono-block amps soldered directly to their respective drivers (with gold solder, of course) with a very short direct feed from an active x-over with a competent source upstream. When will this madness abate???

The most amazing thing about all of this is that I have been doing goofy stuff like this for so many years, and it is still an absolute blast! I dread the day that my ears start giving out. I will have to attempt a direct feed to the brain.

Carpe audiom!!!


gerG

 

[Dusty Chalk]

Quote:

Originally posted by Greg Freeman Fortunately, rational thought was not an impediment. Although I was risking launching 2 tweeter domes across the room to impinge on the distant back wall like a couple of toy suction darts (remember those?)

Great image.

And yes, I remember those.

Here's how you adjust the volume -- you get a different amp for every power setting, and you switch amps. You have a 3W amp, a 5W amp, a 10W amp, etc.

100W amp for ...uh... I dunno, Metallica?

I've done that once, listened while it warmed up...for about a second...way too loud...

I believe the other thing you were talking about is called "bi-amping".

 

[gerG]

" Here's how you adjust the volume -- you get a different amp for every power setting, and you switch amps. You have a 3W amp, a 5W amp, a 10W amp, etc."

I like it!! Volume would be selected by a series of nasty looking knife switches bolted to the wall. I have been looking for a way to work some of those into my system.

fwiw I am already tri-amped. What the hell, if some's good, more's better.

Post hangover experimentation suggests that what I really need is a very good attenuator pot. Thanks to this very website I have a bead on several. My x-over has attenuators built in. but no fun getting the proper tool (a penny in this case) and adjusting 6 pots every time the volume is not just right.

 

[ponzio]

I vote Greg Freeman receive the Hunter S. Thompson award for substance-induced, blatant and gross disregard for convention.

Also, I would like to come to your house to play music really loud, build audio powered rocket launchers, and smash stuff in the backyard. Let me know what day is good for you!