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Its not the shape that effects the rolloff so much. Its the size. Very small baffles make for very early rolloff. In any kind of boxed enclosure (or bowled in this case), you have baffle step loss (unless the enclosures are pushed up against a wall or similar). Its all about the bass waves traveling around the face of the enclosure and canceling themselves out when they meet at the back. Part of the elegant simplicity of OB is that, being dipole as they are, they don't have this problem (they have their own, different problems, of course) BiBs are a good way to work around the problem, too, as they create so much gain at the bottom end that they can easily negate BSC, especially if loaded into the room correctly.

Kensai
 
AutoAudio /Kensai -

Here comes the Blasphemy.

I have nothing but respect for all the mathematicians and guys with testing equipment and far more knowledge than me.

However..... more times than I can count I simply said 'try it anyhow' due to a gut feeling in experiments and got good results.

I've had experts tell me given drivers absolutely would not work on forums but when a more respected member suggested same driver 8 months later same experts objections not so strong and when that member built it and showed all kinds of 'numbers' from test equipment results it immediately was the latest rage.

Go figure.

I try near anything.

Spend some time at Hawthorne Audio and you'll see guys having excellent results with very slim baffles in OB . I've done same with other drivers I simply suspected had decent QTS.

I started doing the bowl thing nearly 2 years ago and I made mine with papermache/plastic resin from a mold. I've had success to my ears with a number of drivers.

I've done OB with bowls in both concave and convex configurations and been happy with some drivers.

'Bob from ST. Louis' is using virtually nothing for a baffle on OB and likes the sound better.

I think the Math gets in the way of our ears before we've given our ears a chance many times.

Try cheap 1st.

If we can Clone a $6000 speaker for $500 and still get the Math right why is it hard to believe we can alter the Math a bit and do it for $300?

Theile and Small weren't around til mid 70's. Some people still think they're full of it.

Just thoughts guys, just thoughts.

Bluto
 
I respect where you are coming from and I do realize that there are a lot of guys on this forum that really don't have $100 to spend on a pair of driver. But....

The awful fact is that you can't make a $20 driver sound like a $2000 driver. End of discussion. You can take a pair of $20 drivers and add $100 worth of materials and knock the socks off of $500 speakers from Best Buy or whatever. If you have realistic expectations, you can achieve you goals.

I've been at this seriously for some 10 years. I started with a pair of 1354's in Weems' pipes. They didn't sound bad at all until I put the 1354's in a proper ML-TQWT. Those sounded pretty good until I put a pair of FE167E's in a MLTL. Those sounded pretty good until I put a pair of DX2's in a MLTL. Each step up produced a real and striking inprovement in the sound.

A couple of weeks ago, I had a demo set up at the Dallas LSAF. I had a pair of BR's loaded with FE207E and a pair of MLTL's loaded with DX2's. Both sets of speakers were EQ to roughly the same FR. Everyone who heard the comparison said that the Fostex sounded very good, but the Lowthers had "life" and were more involving. $200 a pair vs $800 a pair, and take it from my personal experience the $1200 a pair DX3's are that much better.

I surely don't want to dissuade you from experimenting with inexpensive drivers, but don't expect miracles.

Bob
 
I've been trying to tell my wife that, I even showed your post but she wont let me shell out more money. I built some inexpensive full rangers for my son so I have an idea what to expect. They sounded pretty good for what they were, but they also sounded like what they were... small metal speakers.

I don't really have much time these days with a young family that's growing (another on the way) so listening sessions are pretty much out for a while anyways. We don't even have a dvd player outside of our computer so the main thing is just to have some speakers that will play louder then the outside traffic which the built ins on the laptop struggle to do. That being said I still want to get the most out of my money just because I enjoy the hobby. I appreciate all the info thats been given so far. It has been very helpful.

Bruce
 
Hi Bob -

I agree with you 100% .

You were am inspiration to me initially when I found an old piece somewhere on the Net following links with you building stuff on the porch with handtools. Watching your progress gave me Hope. Thus my OSB Adventures began.

All that I take issue with is that sometimes many drivers out there are real 'sleepers' in the low buck category and often the 'Maths' don't have to be as accurate as stated to achieve satisfactory listening results.

What the 'experts' even within the DIY Community hailed as Nirvana 4 years ago is now often considered inferior amongst them when compared to designs of today.

Sometimes I simply think Ego and Competition just won't go away even in this Community. At the same time you'll see this consistent move back to designs from the 30's and 40's and constant arguments oner Alnico vs. todays materials. Sometimes I think it's all a Fashion statement. Line Arrays today, Horns and OB tomorrow.

I own less expensive TB's that sound better to me than CSS I own and I own cheap Oaktons that sound better than both in given applications. I own some JBL's that sound like garbage to my ears.

Will a PHY blow the doors off a Lowthar or a Jordan simply due to cost? I don't know and likely will never be able to afford to tell.

I simply think there is a reasonable limit somewhere within our own hearing combined with our equipment and the room as well as our chosen music.

My next goal is Vintage Electro Voice. I just can't believe A.L. at double and triple the price that much better.

Were I to listen to a DIY Speaker system in the 2k realm and find it extremely impressive I'd end up asking myself if it was the speakers or the guys 5k tube amp that powered it?

I see you've recently moved to a PC based system and I've been reading on that as well. My mind can't get around how anything so compressed can possibly sound good but if you and others I respect are doing such I must be wrong.

Whole point, and reason mentioned is I believe system balance within budget most important factor and therefore somewhat pointless if your actual box size is limited due to room to invest big bucks in drivers if all you can afford to power such with is a T Amp or GC.

At that juncture, perhaps best to grab as much low buck gusto as possible .... it is available.

I highly value your opinion.

Bluto
 
Don't spend a dime if you don't have it

Hi AutoAudio, I think you're saying that money is a major consideration. My advice: don't give up, don't spend a dime, and preserve your domestic harmony at all costs. People are throwing away good drivers all the time. Drivers from cars, radios, old speakers etc.

OB is a great, cheap way to build using oddball drivers you come across, and the dipole sound is so captivating and fun to play with that you might not fixate on the response when you're bathing in the ambience of all those beautiful reflections.

I've had good luck with those nice sturdy double-corrugated Fedex boxes, some duct tape and an exacto knife. OB's, omni's, bipoles, dipoles, nameless monstrosities, anything. (I love the bowl idea by the way.) My home theater is a patchwork of crazy experimental junk but that's part of the hobby for the cash-strapped.

Having said that, I heard Bob's Lowther and Fostex drivers at the Lone Star Audio Fest, and he's absolutely right -- the Lowther's were insanely great. But you're not competing with Lowther's -- you're competing with the cost, so whatever interesting thing you can build out of cast-off parts means you're a winner (and your wife will have no concerns, only admiration).

There's no need to box yourself into a limited budget when there's so much to be had for free. Who knows, you might even come across some truly spectacular vintage drivers in your travels...
 
AutoAudio,
Many of the high-end drivers are truly great (in the proper implementation). They will still be great in a few years when you have more money. In the meantime, in your situation, just have some fun. OBs can be a good choice; also look at some other unconventional set-ups. NORH Audio had some a few years ago that were all the rage for audiophile second systems and for gifts, and they used drums and other locally-built things for enclosures. I also think they used to use Tangband drivers.

http://www.norh.com/

If you are in an area of North Africa where the locals make pots and so forth, you could always have some custom-built as speaker enclosures. If so, it might be a good idea to have them built slightly over-sized. You can always add bricks, for instance, to decrease the volume. You may even find something your wife likes- or let her design the enclosures - and ease her into hifi gently.

Also, word on the low-end Sonic Impact is that, at the least, you will need to change some of the caps to get any real bass below 200Hz.
 
Bluto,

Hope it wasn't me that set you off there. I'm not a math guy or a measurements guy. All I have is a low end pro sound card that give me test done generation functionality, WinISD, that BiB spreadsheet GM put together for us and my ears.

I also don't have a budget. The $65 or so I spent to have a pair of the RS100s and a handful of cheap resistors shipped to me was actually something of a burden. The only reason it happened was because I had been working myself up over them since having seen Zaph's early tests and comments, so it was pretty much a force of nature once the drivers showed up on the PE page. So, I'm totally with you on the "cheap" angle

I've just had some very definite opinions about driver design develop over time, and the RS100s have experientially confirmed alot of them, so I'm very excited, not just because they sound so good, but because they're teaching me things and all for alot less than comparable Fostex drivers (which I'm afraid I wouldn't much like anyway as I suffer listening fatigue very quickly from forward sounding speakers, so I'm loath to toss out $100 or more on a pair only to find them unlistenable).

Now, while I'd love to chance listening to Bob's creations, I also agree with rj concerning low to no budget experimentation. I've got some of that going myself with drivers salvaged from a 1973 set of Sansui monsters.

Kensai
 
Hi Kensai -

I wasn't 'set-off' at all, apologies to You and anyone if it appeared as such.

I was just thinking out loud as to my personal discoveries and A.A.'s situation.

I've just been real surprised in my own experimentation as to how much you can get out of many 'cheap' drivers and hoping to encourage him not to be afraid of any given driver due only to it's price range.

I really believe part of the DIY Community has lost it's way in that regard..... more expensive is not a guarantee to better sound. Often the case, just not always.

I'd bet there are more 'sleepers' out there than we know of.

If you found a Goldwood at $30 that sounded as good as a Seas at $200 would you buy the Seas just to impress other guys on Audio Forums?

Some people actually buy Bose to impress friends. Helps if your friends are deaf. I have a friend that recently heard another guys Bose system and came and told me how great it sounded. I looked at him in disbelief. Then I realized this guy was old enough to remember Bose from 70's. He hadn't heard this new system... he'd heard his memory and all the advertising. I played him my current OB's to get his mind back to reality.

Sometimes being objective can be hard. When I read in another thread that guys making comparison to BIBs with the Pio A11 vs. the Fostex found the Pio superior I pay attention to that stuff. Your mind is going to tell you a Pio simply can't be as good as a Fostex. Why not?

I saw that and went out and bought 8 NOS Alnico 4.5" FR Pio's from the mid 70's from Ebay. I'm bettin they'll sound great.

I like experimenting.

Want some more Sansui's? I'm going to be selling mine pretty soon. Wish I owned a woofer tester, would like to know parameters on those. Possible IB Bass? May just experiment as you with those before I put them on the block.

Can't possibly be as good as a Dayton .... giggle.

Bluto;)
 
Great thread!!! I too like to get the most bang for my buck. Something I tried lately was using some cardboard tubes I bought at a DIY home store. The tubes are what are used for cement footers in the ground. I've found a few websites that help in the design and proper size of enclosures for the driver's specs, so I got some dimensions there. I bought a tube that was 8 inches in diameter and 48 inches long. I used some 5 inch FR drivers I've had for years and cut two lengths of the tube about 12 inches long. After I made a front and rear 12 by 12 baffle, I flush mounted the drivers. I also added some bracing inside the tubes. Although they won't win any awards for sound quality, they aren't all that bad.
I also like to check out second hand stores. I'm amazed at what can be found. There are a couple in my town (Bismarck, ND) that almost always have speakers of differing levels of quality. I've also found some old tube amps very cheap. I found a nice stereo tube amp console for $20 last weekend.
The system I'm using now is a 45 watt JVC amp I got off eBay for about $50 and a pair of ADS speakers I found at a garage sale for $5 each. I plug my computer in to it and rock-out. Actually, last night I was lost in some jazz I found on a free download site.
It's great to see there are others who are more concerned with how the system sounds to the individual, than what the specs say and how much the system cost.
Sometimes I almost get intimidated, frustrated, irritated by all the high-end talk through out the audio world. Now I find this thread and see that there are some audio fans who don't shell out several hundreds for an amp, several more hundreds for speakers, and call it a budget system. Thanks folks!!!!!!!!!!!
With all that said, if I felt more comfortable spending big bucks on audio equipment, I probably would, but I kind of like the challenge of building a great system without breaking the bank. I absolutely hold no ill-feelings toward anyone who can afford to spend a lot for a system and does so because the sound is better.
BTW, I just received a Velleman chip amp kit from Parts Express. I'm looking forward to how it sounds once I've finished it.
Mike
 
A.A. -

Hope you don't see your thread as being stolen - lot of good ideas being tossed around that truly are low buck solutions as well as good advice for mid price point drivers that could be used in cheap smaller enclosures now and eventually moved into better larger enclosures when finances became not such an issue that would simply Blossom in the better enclosure.

Bluto
 
Mikje -

Good post . Sonotubes were a rage a few years back and still to me a great low buck idea.

I'm gona start searching the 2nd hand stores myself cause I keep hearing story's like yours and am tired of missing out.

Your not alone in your frustration. Sometimes I wish I had bottomless pockets and could walk into 'Big Buck Daddy's Audio Emporium' and just start pointing at what I wanted. Wanna get crazy??? Visit the Athens Audio Club on the Net. Million dollar plus systems there, ...........

........ Then I'll read some posts or find a link to some guy who truly knows his stuff (not like me!) who after years of trying it all put together a fairly low dollar system he claims will blow the doors off every big buck system he's ever heard. Limpizator is one of those guys. Google him.

Theres good reason many scour junk piles looking for old drivers.

As you, nothing against the smarter and more affluent builder, I'm just starting to get fascinated by low buck possibilities.

Let us know how Velleman kit works out. Check out new threads here in gainclone section on 'newbee' builds. Both Peter Daniels and a guy named Dan are leading the way on a newbee build .

Bluto
 
Kensai -

Bit O.T. here but had to add this.

I own both a set of Sansui SP1500's and a set of SP2500's. I bought them for a planned Quad system to replace one I had owned in the 70's. Got burned on receiver so speaks still here.

I finally Googled them both and did some research. Pretty amazing. Found out woofers have an SPL of 98-102 db respectively. FS of 33hz measurable to 15hz. They won't take power. 20-50 watts max. With those numbers I don't care.

I'd love to find out QTS and am going to do further research, someone has had to have tested them.

Guys claim they do well with Danmar treatment.

I have some real nice Vintage Marconi's on the way that I'm gona try OB with and thinking now to keep a set of these Sansui woofs for bottom end. If they won't go OB they'd definitely do well in old style scoop horn cabinet.

Let me know what your experiments yield.

Bluto
 
It's more about SAF then budget. I'll probably never be able to spend much money which is ok, I could easily let this hobby consume too much of my time because I like it so much. My wife helps keep in check.

I ended up going with the RS100-4. I've really enjoyed some other of Daytons products and the reviews for them seemed pretty good. I'm going ahead and trying the salad bowls. I've always wanted to give bowls a go and worst case scenario... I'm out 20 bucks. I know they'll be a little on the small side and that'll nix the low end, but my wife wouldn't let me build anything big anyways. When I told her about open baffles... she wasn't a fan. When we have another visitor in several months I'll bull for a little sub and maybe neo tweets. Thanks for all the input folks!

Bruce
 
AutoAudio,

Sounds like you've got a good plan. I suggested locally-made pots or what-have-you because some of the best speakers I've heard were some Jordan JX92S's in ceramic pots a poster named Thor bought at Home Depot. He made round lids to cover the openings and function as baffles on which he mounted the drivers. He also tried Tangbands and Fostexes successfully in the same enclosures. He used some polyfill on the inside, which he had coated with Liquid Nails. They were sealed, but a port could be put on the baffle if a ported enclosure is desired. He knocked a small hole in the back to pass the wiring through, and sealed it with silicone, I think. I listed the nOrh site earlier because of their enclosures. They had a few styles, but the ones that came up if you went there were, I believe, some locally made drums. Supposed to sound quite good, and inexpensive if you build them yourself. You might get your wife more on board if you see what volume you need, tell your wife, and let her choose with you, or design them herself. If you are in an area with skilled artisans, the world is your oyster, and she will have bragging rights to any compliments on how they look. Salad bowls could be great, too. If you can't get the volume you need, you can go oversize and put bricks, blocks of wood, whatever, inside to decrease the volume to what you want. Good luck and have fun.
 
Forgot to add: on the low end, you can always pick up a cheap plate amp when they go on sale at Parts Express (or wherever), get a woofer, and build a little subwoofer to tuck under your desk. The plate amps come with their own crossovers, so you won't need to drop a lot of money. Future project, and can be made to sound okay for not too much money.
 
AA,
If you're looking for a driver for a sub, I might be able to help you out. I think it's great you are keeping your family first and your hobby somewhere down the line (my 29th anniversary- to the SAME woman- is tomorrow- family first!!!). I've got some extra drivers laying around. Let me know if you're going the sub route and we can see what we can do.

To avoid hijacking this thread, I've started one about my first chip amp. Any and all input is welcomed.
http://www.diyaudio.com/forums/showthread.php?s=&threadid=123679
 
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