Post by buzz on 12/09/06 at 00:54:55
Stereo Imperial
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https://www.decware.com/cgi-bin/yabb22/YaBB.pl SUPPORT FORUMS FOR DECWARE SPEAKER PLANS >> DECWARE Imperial support forum >> Stereo Imperial (picture) https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1165629295 Message started by buzz on 12/09/06 at 00:54:55 |
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Title: Stereo Imperial (picture) Post by buzz on 12/09/06 at 00:54:55 Stereo Imperial
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Title: Re: Stereo Imperial (picture) Post by buzz on 12/09/06 at 02:49:10 Drivers are Audio Nirvana Super 10" fs36hz SPL96db XMax1mm Qts0.286 This sounds so fantastic I haven't been able to turn it off long enough to finish the 'wings'... something really special. I can't imagine any speaker being more emotionally engaging. Although its not true to the mono Imperial design I understand how this speaker fueled Steves' first interest in audio. If any one would like to know more just ask. And a special "Thank You" to Steve! |
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Title: Re: Stereo Imperial (picture) Post by gexter on 12/09/06 at 04:50:15 thats a pretty nice looking IMP. who would have thought of using drivers on the side and reflecting the sound. |
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Title: Re: Stereo Imperial (picture) Post by buzz on 12/09/06 at 08:03:32 Steve gave me the idea one day when he mentioned that he had played around with using a cd to horizontally disperse the sound of an up-firing driver. I then tried all sorts of speaker arrangements using various 'reflectors' in the coming months. In my tests I was blown away to hear the 'hyper-stereo' imaging in this arrangement. If you want to hear the effect yourself, turn your drivers 90 degrees away from your listening spot and use LP covers as reflectors. The real magic happened when I bowed or curved the cardboard covers. The transformation was absolutely stunning... from a beamy driver, with my head locked in a vise to get imaging, into speakers with a HUGE sweet-spot! Dispersion like the Gallo Reference 3.1 tweeter but FULL RANGE. And if you get that effect using a piece of cardboard, imagine how great a properly designed arrangement can sound. Even my wife loves the speaker! 
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Title: Re: Stereo Imperial (picture) Post by paulc on 12/09/06 at 11:17:02 WOW! It looks like an antique. Good work! |
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Title: Re: Stereo Imperial (picture) Post by buzz on 12/09/06 at 14:16:15 Thank you! I was really only trying to make this beast look good enough to be in the house instead of in the garage. Here are a couple more detail shots... Maybe they can help someone increase the WAF of their own Imperial. (Everything was purchased at Lowes. Total cost was around $500 including drivers. Assembly and finishing took two days.)  
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Title: Re: Stereo Imperial (picture) Post by Chris K on 12/10/06 at 15:56:50 Hey Buzz, That is a cool Idea you came up with there!!!! ;D Is that Imperial scaled up or is your wife a very petite gal? The original Imperial is 62" or 63" tall. What did you do (if any) to modify the driver chamber size? Did you extend the throat any? This can be done by running a board down the front behind the (what would normally be) the front baffle thus narrowing the throat a bit for better or more optimal loading at low bass frequencies. This information I read in the tech papers by Jensen engineers at the time of the design (1956?) Interested to hear what you did with these points of detail. If it is as simple as doing a standard Imperial and putting the drivers and wings on you may well have revived the standalone console stereo!!! |
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Title: Re: Stereo Imperial (picture) Post by buzz on 12/10/06 at 18:41:51 The only modification to Steves Imperial plans was to port the middle support of the chamber. In this way left and right channel cross talk is eliminated, however bass frequencies are summed. This also is a fantastic solution to in room bass node cancelation that all stereo two woofer systems have to deal with. The effect of summing L&R channel low frequencies is a perceived increase in bass response, even-though actual response is flat everywhere in the room. This was a groundbreaking realization to me. P.S. My favorite quote from the Imperial build was when my petite wife said "These things are huge!" My response ?... "No honey they're not big, you just think that because of their dimensions." |
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Title: Re: Stereo Imperial (picture) Post by buzz on 12/10/06 at 18:53:49 I forgot to add that the 'wings' are on hinges. The reflected sound can be focused from a tight window with tons of detail (critical listening), to a room full of stereo sound with less detail (party time!). 
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Title: Re: Stereo Imperial (picture) Post by footstony on 12/13/06 at 02:51:59 Buzz that speaker is awsome! really nice finish, I can't think of what to type I am so totally stunned by your original thinking. Last night I was looking at the JBL paragon and this design has some similar ideas. http://www.audioheritage.org/html/profiles/jbl/paragon.htm Thanks for sharing. Philip |
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Title: Re: Stereo Imperial (picture) Post by buzz on 12/13/06 at 11:13:30 Nothing is new under the sun. The JBL is proof. Speakers that use reflected sound probably have been around since the begining of audio. Thank you for the info. Now I may try to build that paragon! I wonder what drivers are availible for this application... Any Ideas? And what in the world is a "Ring Radiator Overtone Reproducer"? ???  
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Title: Re: Stereo Imperial (picture) Post by footstony on 12/13/06 at 22:44:58 Buzz, I'm not really a JBL expert but I think it was a bullet tweeter. As used in the bel-aire http://www.audioheritage.org/html/people/wolf/connection.htm More info on the Paragon's indusrial design press the "next" button at the bottom of the page Regards Philip |
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Title: Re: Stereo Imperial (picture) Post by dank on 12/22/06 at 13:31:51 Buzz You are an experimenter. Here is something you might want to try. If your room responds the same way mine did, you will be shocked, stunned, and amazed. Turn your Imperial around so the horn fires directly into the corner. You will have to reverse your deflector "wings". Also, if you haven't read Steve's paper "how to set up a room with no treatment", available under the "my room" tab on the Decware home page (www.decware.com), you might find that interesting as the second half of the paper basically talks about a setup that you would have if you have a single sub in the corner of a listening room with your mains positioned appropriately on either side of the sub. If you try this, please let me (us) know what your results were. My room sees a bass increase of 6db plus a wonderful feeling that the bass is enveloping you rather than just being played at you. Dan |
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Title: Re: Stereo Imperial (picture) Post by buzz on 12/23/06 at 12:16:17 Thank you Dan for the tips. Give me some time to put my thoughts into writing on corner firing horns. Yes, a substantial rise in bass output... any trade offs? I haven't decided yet. I also have a new project in the works. Plus, a Gallo Reference 3.0 vs. Jensen Imperial shootout I want to share my thoughts on... All the best! Buzz |
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Title: Re: Stereo Imperial (picture) Post by 60ndown on 12/23/06 at 14:22:06 buzz wrote on 12/09/06 at 08:03:32:
whats going on in bottom left corner of this pic? there seems to be a piece of wall out in the middle of the room? ??? |
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Title: Re: Stereo Imperial (picture) Post by buzz on 12/23/06 at 16:32:48 The time/date stamp of my camera was wrong, I decided to block if off to not confuse everyone... I guess I was unsuccessful. :'( |
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Title: Re: Stereo Imperial (picture) Post by BIG_GEOFF on 12/23/06 at 21:42:17 I think hes hiding something ???... |
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Title: Re: Stereo Imperial (picture) Post by Terry on 12/24/06 at 07:49:31 Yes he is hiding his bottle of beer, but what brand. TG :) |
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Title: Re: Stereo Imperial (picture) Post by buzz on 12/24/06 at 11:57:46 You caught me, Only the BEST in my home... 
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Title: Re: Stereo Imperial (picture) Post by Jet-Lee on 12/25/06 at 16:00:58 ewww :spit: :spit: :spit: The right stuff...  Back On Topic.. How much did those speakers set you back, if I can ask? Worth it, or can better be had for the money? |
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Title: Re: Stereo Imperial (picture) Post by serenechaos on 02/05/07 at 02:25:27 buzz wrote on 12/10/06 at 18:41:51:
I'm not sure I understand what you did here. By "port the middle support of the chamber" do you just mean divide the chamber in two halves, sealing the drivers from each other? I think I want to try building one of these, about like you did, but starting with the corner version, instead of the rectangular version. Robert :) |
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Title: Re: Stereo Imperial (picture) Post by buzz on 02/05/07 at 07:16:21 The idea is to keep the compression chamber volume the same as called for in the original Imperial design. It is tuned for low frequencies because of its large volume. If you divide that chamber into two halves you will change tuning (bad for the design of this bass horn). However we need to separate the higher Left and Right channel stereo frequencies. How can we do that while still maintaining the full compression chamber volume? It can be accomplished buy cutting holes in that center 'divider', the important part is to cut holes that only allow the frequencies you need the chamber to resonate at to pass through. Here is a hint... just like any ported box or even any guitar, two smaller diameter ports can resonate at a lower frequency than one larger diameter port of the same length. |
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Title: Re: Stereo Imperial (picture) Post by serenechaos on 02/06/07 at 01:01:44 ??? So it's a secret, & you're not telling? |
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Title: Re: Stereo Imperial (picture) Post by buzz on 02/06/07 at 08:13:47 :-[ Try two 3" diameter 'ports'. It may or may not work depending upon the drivers you choose. |
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Title: Re: Stereo Imperial (picture) Post by serenechaos on 02/06/07 at 17:52:15 buzz wrote on 02/06/07 at 08:13:47:
I had in mind trying those Audio Nirvana Super 10" you said worked so well. If i couldn't get them to work, trying a JBL D130 in the center as a woofer, and "something else???" in the sides. Robert :) |
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Title: Re: Stereo Imperial (picture) Post by buzz on 02/06/07 at 21:31:19 Oh, you mean something like this?...  The top driver is the Decware 10" woofer, DHM108B. Four ten inchers, they rattle my brain. |
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Title: Re: Stereo Imperial (picture) Post by serenechaos on 02/07/07 at 00:40:36 No, I meant the Audio Nirvana Super 10s in the sides, and the JBL 15 in front. Seperate compression chambers for each, opening into the throat, which becomes common. The 15 would be mono, the 10's stereo. Don't know if it would work at all. ??? Did the extra 10s help? More bass? What are you side "wings" made of? Wood? Fabric? (Reflective or absorbant)? Thanx again, Robert :) |
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Title: Re: Stereo Imperial (picture) Post by buzz on 02/07/07 at 00:48:42 If could do it over again I would not put in the second set of drivers. The Audio Nirvana drivers have such tight realistic bass it is amazing. I may end up trying a second set of AN in place of the Decware. I think the key is the small Xmax. For your 15" woofer keep the Xmax a short as possible, the Qts as low as possible. Fast tight bass is what makes the Imperial horn so engaging. But without a second set of drivers I felt that I was wasting SPL that the Imperial is capable of. The 'reflectors' are 3/4" kerfed (so they bend) oak plywood. I also tried acrylic, lexan, glass, cardboard and foam. Oak was by far the best that I tried... but maple would probably be better. |
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Title: Re: Stereo Imperial (picture) Post by serenechaos on 02/07/07 at 02:52:02 The D130s are 0.25 qts, 0.76 X-max, light paper cones. Should work well in horns. About how big are they; how much bow? Have you played around with that much yet? Did you make the cabinets out of oak ply? What did you stain them with? Sure do look nice! |
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Title: Re: Stereo Imperial (picture) Post by buzz on 02/07/07 at 10:42:10 serenechaos wrote on 02/07/07 at 02:52:02:
To me the Xmax of the D130 is still too high at 3/4". Remember total cone travel will be double the xmax (1.5 inches!) (OOPS .76mm! WOW!) The Audio Nirvana only 2 millimeters. But your right, the D130 is a good driver, and will probably have tons of bass. The kerfs in the plywood have not been glued yet. The reflectors can be flexed from flat to convex to a concave shape. This is easily done and you should decide for yourself what sounds best. They are sized to the dispersion pattern of your driver. The cabinets are pine floor sheathing ~ $20 / sheet (the same as what Steve used on the walls of his shop, and have suprisingly great sound https://www.decware.com/cgi-bin/yabb/YaBB.cgi?board=room;action=display;num=1169858290 ) But, I would use maple next time. The finish is Minwax oil based one step gloss stain. 1st, Bombay Cherry and then Natural Cherry. A couple coats of each. Your house will stink for weeks. ;) |
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Title: Re: Stereo Imperial (picture) Post by dank on 02/07/07 at 16:14:31 The JBL D130 has an Xmax of 0.76 mm (not 0.76 inches). I've refered to it as the speaker with the non-existant Xmax. Dank |
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Title: Re: Stereo Imperial (picture) Post by buzz on 02/07/07 at 16:39:40 Oops, my bad... That sounds fantastic! Why use just one? |
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Title: Re: Stereo Imperial (picture) Post by Mr Content on 02/08/07 at 11:34:52 Well Buzz, I have to say thats the first imperial that I can stand to look at. Nice job of diguiseing the beast. Mr C :) |
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Title: Re: Stereo Imperial (picture) Post by gexter on 02/08/07 at 11:45:12 even a cardboard Imperial is a beautiful thing! But its nice to see more of a furniture spin on it. G |
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Title: Re: Stereo Imperial (picture) Post by buzz on 02/08/07 at 12:11:52 Mr Content wrote on 02/08/07 at 11:34:52:
Thank you, When people come over for a visit they want to know what kind of television is inside.... 
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Title: Re: Stereo Imperial (picture) Post by Mr Content on 02/08/07 at 21:03:06 Hey Buzz, you could easily hang a small LCD on the top section. Great use of the realestate. :) Mr C :) |
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Title: Re: Stereo Imperial (picture) Post by buzz on 02/09/07 at 12:32:37 Mr Content wrote on 02/08/07 at 21:03:06:
Good morning Mr C. Yes, I imagine so. This may sound odd, but I despise television. I do enjoy a movie now and then, but I haven't watched television for over a year now. I have better things to do with my time, and I could care less about what is on it and the views of the people who control it. Thanks again for your great Open Baffle posts... patiently waiting for your bafle dimensions :D |
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Title: Re: Stereo Imperial (picture) Post by Mr Content on 02/09/07 at 19:56:01 Howdy Buzz, its in the mail. :) Yes TV is a bit on the boreing side isn't it. Mr C |
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Title: Re: Stereo Imperial (picture) Post by Rap on 02/10/07 at 21:08:31 Mr Content wrote on 02/09/07 at 19:56:01:
Have you tried the other channel? :) |
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Title: Re: Stereo Imperial (picture) Post by serenechaos on 02/11/07 at 01:00:19 It has channels? I don't even own one of the things! My wife bought one a couple years ago to watch a training tape from work. I don't think she's turned it on since either... Robert |
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Title: Re: Stereo Imperial (picture) Post by Mr Content on 02/11/07 at 01:04:59 we have 6 channels on the Christian sat. Thats about enough for us. :) Mr C :) |
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Title: Re: Stereo Imperial (picture) Post by serenechaos on 02/11/07 at 01:12:49 buzz wrote on 02/07/07 at 16:39:40:
That's what the box was designed for. One 15" driver. So I'm guessing the compression chamber should be closer to right for one. I really like what you did with the Audio Nirvanas in the sides tho, and am still scratching my head on whether to try implement something similar. And whether to build the rectangular version, or the corner version... |
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Title: Re: Stereo Imperial (picture) Post by dank on 05/23/07 at 14:45:53 Buzz Did you look at and reject the 12" Audio Nirvana's? Fs = 33.5, Qts = .487, Vas = 10.3 cubic feet, Fs/Qts = 69 The 10" actually looks better for a horn loaded cabinet, Fs = 36, Qts = .286, Vas = 3.6 cubic feet, Fs/Qts = 126 but I would think the bigger speaker would do better - actually I'd prefer a 15" but they don't make them. The thought is to put a single full range speaker in a standard Decware Imperial DanK |
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Title: Re: Stereo Imperial (picture) Post by Cosmos on 06/08/07 at 14:07:59 serenechaos wrote on 02/11/07 at 01:12:49:
Thinking out of the box, a person could use just a mid bass/ tweeter or maybe better just a full range (Fostex) outside of the main compression chamber mounted on a open baffle wing with another wing as a reflector? this would give a multitude of directivity options and tuning.. That could be worth a try! |
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Title: Re: Stereo Imperial (picture) Post by serenechaos on 06/09/07 at 14:42:33 I was thinking of doing just that. (closer tuning than stuffing everything in the same BLH (back loaded horn)) Don't know exactally what to really expect for frequency response from Imperial, or how to design around it. Went through threads here, and other places. It looks like building a Klipsh horn would be a better sub, up to ~400 Hz, and slightly smaller footprint. And it's front loaded (more efficient). Not to sure about integration between the FLH or BLH and OBs though. And never really liked the sound of OBs that much. Sound too much like bose 901s-- reflected sound bouncing off the back and side walls. Project on hold... |
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