| Harderror |
| I just built a set of DBR's and am thoroughly impressed. I used the old standby W3-871's from Tang Band. I can't believe the amount of clean balanced bass that can be achieved in a 7x11x9 inch box. I keep having to check to make sure that I don't have a set of my larger fostex boxes running. Anyone else had much experience designing these? My first shot at a design is a success and I plan on designing some enclosures for my 127's this weekend. |
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| youyoung21147 |
Hello !
Another guy who was able to get bass from these nice cheap drivers ! Good work ! Have you got any photo ?
I used a bit different way to build mines : a big ML-TQWT. See my website if you're interested ! |
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| no xo |
| I`ve built the Fostex recommended double BR for the FE127`s and had the same reaction. I made the boxes about a foot taller and filled the bottom chamber with sand to act as an integrated stand for floor mount. I made these for my GF and they`re hooked up to a cheap Onkyo receiver and mainly used for video, but I was very happy with the sound. I have a pair of FE207E`s in a large BR box and will eventually build the Fostex recommended double BR because I was so happy with the smaller ones. She has them on the sides of a 32" TV in the corner and the bass that little driver makes is tuneful and extended. When I pull off the grilles to show people what`s inside they can`t believe it. "Testimonial from another satisfied customer." |
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| Harderror |
| I will post photos soon. The boxes though are only 11 high x 7 wide by 9 deep. All in inches. I noticed in another thread that someone (SM) stated that he couldn't get rid of the variations brought on by the dual chambers where they collide. This confused me as DBR boxes are known for flattening out the frequency response more so than standard bass reflex speakers. Short of a small 8 db null from 100-130 Hz, (Which is room mode dependant), my response is surprisingly flat. Moreso than a BR with this driver. I believe that what some people refer to as the small chamber vs. the big chamber problem is just that. You do not need a drastic difference in chamber size, only the tuning of the chamber. I find that if I simulate it with a larger secondary chamber that the freq. resp. begins to flutter. Comparing these boxes to the Needles that I originally built for the TB drivers, the bass is cleaner and smoother. When they are placed 8" from the wall, the bass response increases quite a bit as well. I can easily listen to them without the need for a sub. Not bad for a sub-bookshelf variety speaker. I have been trying different tunings for each chamber as well and am compiling data on the subjective as well at the scientific findings. |
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| LightwaveDude |
| DCR designs sound very interesting. Does anybody know of any simulation programs that will graphically show what the excursion and FR response are doing in a DCR box? I've looked online and I've heard that lspCad will do it, and I have the demo version..... but it's way over my head how to design/layout such a box. Does anybody know of a simulation program (or has anybody designed a system in lspCad & is willing to share it?) |
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| lovechild |
Hi
Martin J. King's Mathcad worksheets will simulate DBR or DCR systems.
Go to http://www.quarter-wave.com/ and click on 'Upgraded MathCad Computer Models'
best, LC |
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| Harderror |
| Actually, what I am simming my DBR's with is Martin King's worksheets. They have worked very well thus far. I will keep everyone posted as to my progress. |
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| neil_kaye |
I built a pair of DBR's using Fostex FE83's.
http://web.mac.com/noteldov/iWeb/DI...5C6545F1E9.html
As expected, great mids and highs but the bass was almost non existant. I had to mate them with an active sub. With little bass the soundstage was also pretty shallow.
I could not get over how fast and dynamic the speakers were though. Even with little bass they were great near rnage speakers and if you like jazz I owuld give them a go. |
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| LightwaveDude |
| quote: | Originally posted by Harderror
Actually, what I am simming my DBR's with is Martin King's worksheets. They have worked very well thus far. I will keep everyone posted as to my progress. |
I've looked at Martin King's worksheets, but it appears as though you have to pay to access them...:confused: is this correct? Does anybody know of a free way to simulate DBR/DCR's. (I'd still like help simulating it in the lspCad demo). |
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| Bob Brines |
| quote: | Originally posted by LightwaveDude
I've looked at Martin King's worksheets, but it appears as though you have to pay to access them...:confused: is this correct? Does anybody know of a free way to simulate DBR/DCR's. (I'd still like help simulating it in the lspCad demo). |
$25 for God's sake! You want ten years of hard work out of the man, and you begrudge him a little return on his efforts? Pay the man his dues and get the REAL answers to your problems.
Bob |
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| no xo |
| Right on Bob. How much $ per hour does that work out to be? |
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| john65b |
Huh? I thought DIY was "open source", and that profiting from DIY was not the in the spirit of DIY...
I would hate to pay big bucks for a self promoted, hyped up amp/speaker design that may ultimately dissapoint... since there's no way to audition or prove the design...
If a free DIY design does not pan out to my expectaions, I only have myself to blame, but to pay for a design is another story.
Maybe this guys designs are worth every penny, but again, seems out of context for DIY...
I say stick to the free, where there no conflict of interest. If you want t buy a design, get something you can audition for yourself... or temper your expectations...
After all, it's your money... |
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| LightwaveDude |
| quote: | Originally posted by Bob Brines
$25 for God's sake! You want ten years of hard work out of the man, and you begrudge him a little return on his efforts? Pay the man his dues and get the REAL answers to your problems.
Bob |
Well, the biggets reason I don't want to pay for anything is 1) I'm just curious about the DBR/DCR design and 2) I don't plan on building one since I haven't even completed my normal ported sub. 3) I don't think I'd put that cost to good use since I don't have any practical reason for designing transmition lines, horn loaded systems, or any of the more exotic systems at this point in time that his worksheets model. I'm just curious about how these systems perform. I don't have the time or money to build any of these (poor highschool student speaking here).
Lastly, the problem with my parents come into play. I doubt I could convince them to pay for something online (I assume you need a credit card or something to pay online) from somebody who they don't know and doesn't have a business registered with the BBB where they could check the credibility. I know he wouldn't be out to rip us off, but convincing my parents is another issue.
I'm not trying to rip him off from his hard work. No offense was meant; my quest for a simulation of a DBR/DCR was more of a curiosity than any practical need. |
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| no xo |
| Lightwavedude and john65b, my feelings are, we pay for the parts, materials and all other necessary elements that go into making or designing speakers. I believe that proven information is a necessary element, just as drivers, baltic birch and all the other stuff(ing) which help us achieve our goals,and are of value. Usually we get what we pay for. Free is almost always good, but to get the right info, parts, ect., cost is usually asssociated. I don`t think either one of you are wrong, I just post my opinion with hopes not to offend anyone. I am a greenhorn (new to horn building and DIY), and this site has helped me have more fun with audio than I`ve had with 30 yrs of playing with commercially built speakers. My expirience is limited, my opinion is not. Have fun and enjoy the process. NOXO |
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| MJK |
Stick to free. :)
Do it yourself. :)
Those are how I got started and well worth the effort in my opinion if you really want to learn speaker design.
You will learn more, understand more, enjoy the outputs of your designs, and take great satisfaction in the results of your efforts. The longer road to success, took me 20 years.
Best of luck to you both, |
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| john65b |
Halleluiah!!!
I mean no offense, sir, and glad you can agree.
There is much to be learned in DIY...otherwise we all would be watching Oprah right now......and listening to Bose speakers (ouch!) |
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| no xo |
| Martin, maybe I should have worded my reply like this, I value your attitude and your research. Thank you |
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| pinkmouse |
| All I will say is that Martin's worksheets are a tool, just like a decent soldering iron or router. As with all tools, what you do with them is up to you, but the right tool makes the job so much easier and more enjoyable. ;) |
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| MJK |
| quote: | | I mean no offense, sir, and glad you can agree. |
No offense taken. I appreciate the support of the other people posting comments.
DIY is great and people work to different levels. If you have the engineering/math background and are willing to invest time reading, studying, rederiving equations, and then programming the results it is a real fascinating exercise and hobby. I have been working at it on a part time basis for over 20 years. I have a lot further to go.
So the DIYer has to decide to spend the time (maybe you are quicker then I am) or spend the $25 to accelerate the process. I rarely spend money on software when I can do it myself and in my own way. For me half the fun is deriving and programming the software and then correlating it against test data. You learn more this way, but it is hard work. |
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| LightwaveDude |
Martin, I'm wondering if you can supply exactly what I'm looking for. Can you do something to visually represent what a DBR will do to cone excursion? Can you just give a plot of excursion of any driver in a normal bass reflex design and then give an excursion plot of the same driver in the equivalant DBR box?
I was mainly looking for modeling software not to design my own system but to understand the descriptions I was reading... the biggest confusion of mine being the excursion of a DBR box. I've read that it helps full range drivers in that it reduces cone excursion in two pass bands, but how much of a reduction?
If I ever get the money to start designing more systems, and systems that aren't the standard sealed or ported enclosures, I'll definitly look into your worksheets. The tutorial page looked like your worksheets cover just about everything, and they could be very valuable tools. Unfortunately, you won't have an invester out of me yet, but I admire the work you have put into the worksheets.
Also, I too am glad you didn't take any offense. I didn't want to come across as demanding everything come to me for free.
Thanks, Logan |
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| MJK |
Logan,
I hope you don't take offense. You are asking me to do work for you. As was discussed several times above, I think you are clearly in the DIY phase of speaker building. |
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| LightwaveDude |
Nope. No offense taken, but I've always been told it doesn't hurt to ask!
:D Thanks
Logan |
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| Zero One |
Hi there lightwave and interested DBers.
I have built DBs based on the fostex design (127) and used different drivers in them as an experiment, overall the DBs work really well, in fact far better than I thought possible.
I have no program for simming and I don't even have the parameters for the drivers I used, they were cheap, but I managed to get there eventually, there are of course many variables, bottom and top chamber size, internal port length/diameter and the bottom port.
Basically I just experimented with everything in sacrificial boxes, in other words i didn't care how trashed the boxes got as they were just prototypes.
So heres an idea make a basic pair of boxes that are larger than you think you'll need and make sure the divider inside the box is not fixed so you can move it up or down, if you make the fit tight enough it should hold for experimenting.
The bottom chamber can be adjusted by using blocks of wood or other solid regular shaped objects or even sand in known quantities. Ports can be adjusted by using cardbaord tubes that can be cut at will.
Try a top port dia of 65mm or so and 60mm lenght, though you will likely not finish with this and adjust the top chamber until the mids/highs sound right, then adjust the volume of the bottom chamber until you start to get some bass happening with a shortish bottom port tube (say 60mm by 60mm), then you can start tuning port lenghts, but don't tune the top one too low say around 100hz or so.
To make it work you will need a CD with some tone sweeps or test tones on it at everything from 20hz through to say 16khz.
I know none of this sounds really scientific, but it will work if you persevere and you will probably end learning a heap about how port lenght and cab size effects the sound.
OH and there are other things that I imagine most simms don't take into account that you can play with too, like distance from the walls/corners, height from the floor, the resonance of the cabs, the type of stuffing you use in the cab, mods to drivers and much more, all these things can have big time effects on the sound IMHO and are likely hard to predict via programs alone.
Go ahead have a play with some cheap drivers and cabs, you have little to lose and a heap to gain.
Programs would I'm sure help a lot in terms of cutting down the time involved and I really admire the guys who have created them, but in the end I'd say they would land you in the ball park and theres no guarentee you will like the way they sound without fine tuning anyway, after all what you and I think sounds good is pretty personal.
Hope it helps. |
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| DAMIC |
Hello,
I just now discovered this thread, I am glad that some other members also achived unusaly good bass response with DBR. It seems that I accidently made DBR, increasing the volume of my stock hybrid speaker, last week I posted the topic under the speaker page: Apogee C/M mod – what I ended with
http://www.diyaudio.com/forums/show...&threadid=83867
I am still curious, how astonishing bass performance achived with 6,5 inch driver.
Best regards |
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| Zero One |
| Yeah, you sure can get great results, I have had many friends lsten to mine and they have all commented how good the bass was considering the driver size. The thing I like however is that the bass is nicely tight and very tuneable. |
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