| Glowbug |
I've got the urge to build something as an afternoon project, something I can use with my NAD 3020 as a backup system now that I've got the main rig glowing in the living room :D
So I'm thinking about a pair of OB speakers. Where I'm using the NAD, I don't need a ton of efficiency like I would have with the triode amps. Problem is, I can't seem to find plans out there for simple OB speakers that use easily-found drivers. All the ones I see are for rare or very expensive ones :(
So what are some cheap, easy to find (@ Madisound, PE or elsewhere) speakers that have potential in OB? What size baffle should I start out with? |
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| ozmattk |
Either the Silver Iris or for true fullrange but less bass, the Visaton B200.Or any driver with qts of .7 or greater and a reasonably low Fs, say 50hz or less
For cheap find an old console stereo and get the speakers from that,I did it this about a month back with some 8 inch Rola drivers in 3 foot tall x 2 foot wide baffles and it works very well.
If you have the space try these-
http://members.myactv.net/~je2a3/open.htm
Check the Hawthorne Audio site forum, some discussion there regarding baffle building.
You can download a spread sheet here-
http://www.t-linespeakers.org/downloads.html
(baffle xls) and it will show the effect of different size baffles and different drivers on frequency response. |
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| Glowbug |
Hmm...that talk of the 10" drivers makes me almost want to wait...but the 15's are tempting as well :D
Thank you for the link, I think I've found something to drool over ;) |
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| johninCR |
The 10's won't qualify for full range due to the higher Fs.
For a really cheap shot at OB, try the $24 pioneer B20 fullranger at partsexpress, then add a tweeked out piezo for the very top end. |
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| Nanook |
I've built em and love em.
Do not alter the dimensions or location of the primary driver. But you can alter the back "shelf", making it full width (about 30" long) instead of 6" or so. Bass is improved.
As Mr. Esmilla suggests, finish (cosmetically) the loudspeakers before you listen to them, or you'll never take em apart to finish them:-) |
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| Glowbug |
The only thing that bothers me about the 15" Silver Iris's is the fact that people are saying the 10's are "faster"...now, I've been around this sort of thing long enough to know that inductance plays a larger part in transient response than Mms does, so what's going on here?
I just don't want to have sloppy midrange as a tradeoff for deeper bass. I can always add a small sub to take care of the sub-60Hz material.
I'd build the JE Labs version, except my room is a little small for that...not sure how well I could fit the baffles in there. A taller but narrower baffle would fit better. |
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| MJK |
| Have you thought about using one of the Fostex full range drivers, maybe a FE-167E, and a 15" HE woofer crossed over someplace between 100 and 200 Hz? Would not be too expensive and I have to believe very nice sounding. I think a full range driver and a big woofer makes a lot of sense. Baffle could be 20 to 24 inches wide by 40 to 48" tall with a pair of hinged wings. |
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| Scottmoose |
15in Daytons should do the trick.
Don't always believe that big cones are automatically slower than smaller ones BTW. It's not true, at least with well engineered ones. The cones tend to be pretty light, and having a large surface area they don't need to travel as far. |
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| MJK |
I have not done any design work, but consider this combination as a starting point.
Full range driver = Fostex FE-167E or 166E, each is 94 dB efficient ($63 each)
15" Woofer = Eminence Alpha series 15A, each is 97dB efficient and Qts = 1.26 ($58 each)
or
15" Woofer = Eminence Beta series 15, each is 98dB efficient and Qts = 0.59 ($72 each)
Crossover = Behringer CX2310 ($90)
XLR Cables = six required ($50)
Total Cost = 2 x $63 + 2 x $58 + $90 + $50 = $382 plus wood.
I can say that a 15" woofer with a full range driver is extremely efficient and produces great dynamics. You can see my Project 7 for an example of this type of system. Again, I have done no design work but this looks to be a good starting point at a reasonable cost. |
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| Nanook |
have a look at this link
a smaller baffle that the author suggests is exactly what he wanted. |
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| MJK |
| Think small ... you get small. He was discussing 15" drivers, so I made a suggestion of a combination I thought was promising. If I missed the mark, I'll back out of the discussion. |
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| planet10 |
So far, i'd classify most of the suggestions so far as medium expensive...
I'm reserving judgement on the Silver Iris 15 until i hear it with the new HGD XO. With the original XO i couldn't live with them. They do produce a wonderful, larger than life soundstage with a lot of bloom in the bass. The 10" will be interesting. The Visaton B200 i could live with (but can't afford).
If you want a truly cheap OB, you need to look at vintage recycled drivers. I have drawers of candidates (and could point to some of the more interesting ones that get onto eBay). With any open baffle the depth of the bass is largerly determined by the size of the baffle (althou JohninCR has done some interesting work with baffle shape). A high Q driver will have a more or less ideal baffle size which has OB cancellation in just the right place to lower the Q of the system. A higher Q driver will need a smaller baffle. To get real low bass you need to move a lot of air, and even for the 15" SI there is an auxilary woofer -- which gets us back to Martin's big/woofer, FR as midtweeter approach. To do this passively you need to get drivers with similar efficiency (not always easy) and XO above 200 Hz.
As a side note, when i was selling 3020s new, i sold quite a few with Quad 303s, PS Audios, Haflers, even NAIMs for use in bi-amped systems. A 3020 + a gainclone would be today's equivalent.
dave |
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| planet10 |
For something like that i always consider a 1st order series XO 1st (check Andy Graddon's site).
And with an XO over 200 Hz, you could consider the FE166e as well, but considering the differences in the efficiency, and not wanting to burn as much power in a series R as in the FR itself, you would do well to consider FE127e instead (despite 92 dB claimed it is probably closer to the 90 specced for the woofer). It is also about half the price, and it gets way better once modded. Even stock it has an edge on the 167 thru the mids & top where it would be used.
dave |
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| ScottG |
You can't go passive with these drivers - the PE woofer is to low in eff. and fs..
Think of the PE woofer as an open baffle *powered* sub driver when used in pairs per channel.
Dave has the best idea at low cost.
Martin's suggestions are somewhat problematic for the lower and mid - midrange for a passive implementation unless the baffle is huge.. and I think thats what he is suggesting with the "wings".
There is one 15 inch driver that seems to be about right for the upper bass lower midrange in a passive implementation.. :confused: :apathic: :D |
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| Nanook |
| quote: | | I'd build the JE Labs version, except my room is a little small for that...not sure how well I could fit the baffles in there. A taller but narrower baffle would fit better. |
I was just suggesting something that may be smaller than the "JE Labs" OB, that reportedly fit the bill for the thread author in terms of size (as in smaller baffle than the "JE Labs" dimmensioned OBs).
Here's perhaps something closer to what MJK and others have suggested as far as a taller, narrower baffle |
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| MJK |
| quote: | Full range driver = Fostex FE-167E or 166E, each is 94 dB efficient ($63 each)
15" Woofer = Eminence Alpha series 15A, each is 97dB efficient and Qts = 1.26 ($58 each)
Crossover = Behringer CX2310 ($90)
XLR Cables = six required ($50)
Total Cost = 2 x $63 + 2 x $58 + $90 + $50 = $382 plus wood.
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OK, after playing with my MathCad OB worksheet for a few minutes, here is what I get for a response.
http://www.quarter-wave.com/OB_2_Drivers_5_09_06.pdf
This is a 40" tall and 24" wide baffle, looks pretty good to me. |
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| el`Ol |
From my experience the Peerless SLS drivers don`t have the punch to match a good fullranger. On an other forum I read about a similar experience with large Eminence drivers.
Here is something with less Mms:
http://www.teleprodottistore.it/shop/ciare/cw250.pdf |
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| amt |
Martin,
Am I reading this correctly? A fairly flat response down to about 50hz @95db efficiency, using one Alpha15 and no eq? Im assuming the 2db boost is the woofer amp operating at higher output than the Fostexs' amp or does the crossover have boost?
amt |
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| MJK |
| quote: | | Am I reading this correctly? |
You are reading correctly.
| quote: | | does the crossover have boost? |
The crossover has a boost applied, the Behringer unit can go +/- 6 dB if I am reading the manual correctly. My dBx Driverack PA also has a boost capability. |
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| hurdy_gurdyman |
| quote: | | The only thing that bothers me about the 15" Silver Iris's is the fact that people are saying the 10's are "faster"...now, I've been around this sort of thing long enough to know that inductance plays a larger part in transient response than Mms does, so what's going on here? |
Jim,
I was just reading this and thought I'd reply. I mentioned the 10" SI drivers as being "faster" sounding.
http://www.hawthorneaudio.com/forum/viewtopic.php?t=206
That was just a day after receiving them to break in. After a few weeks of listening, I would call the sound "leaner", not "faster". At this point, I actually prefer the sound of the 15 SI's. The mids are better, to my hearing. I haven't designed perfectly matching Xo's for the 10's yet, so maybe they will be better then. Remember, at this points, the 10's may not be the final product. Changes could be made. Won't know until I get around to making a Xo and listen some more. The two drivers do sound more alike than different, though. The difference is small. The 15's have a bit more powerful sound when pushed, as is to be expected.
In a narrow open baffle, there is nothing lacking in the transient department of the 15 SI coaxials. I just heard Darrel's system the other day. In a large living room, the sound was fantastic! It's still good in my room, but you can really hear the difference. I'm looking into room treatment to absorb rear reflections. I have a noticable bass bump in the 80-100 Hz range with all the speakers I've listened to in this room. Makes it hard to do good evaluations.
Dave:) |
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| johninCR |
Dave,
Have you tried your 15's outside yet? My at the beach listening with the speakers about 15ft in front of a wall and 12-15ft apart is the best concert sound I've ever had. My well treated room can't touch it. |
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| hurdy_gurdyman |
John,
I live in town. My neighbors might not appreciate the outside "noise". I do think room treatment will help, but I know there is no substitute for a big open space. I just need to fool the SI's into thinking the room's bigger.
Dave:) |
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| amt |
I noticed that the worksheet for the Fe167 + Alpha 15 is gone. Sadly, I forgot to save the pdf file. So I checked Martins website to see if it might be there and I see he has tried the Alphas and likes them better than the more expensive Daytons! Great!
Im thinking of using just a single Alpha with my Fe166ESRs and the Behringer. Wonder if the baffle could be made just taller to accomodate two Alphas if I decided to go that route? Martins baffle is way too big for my room. Im guessing that the higher Qts would allow the narrower baffle.
amt |
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| DrDeville |
| quote: | Originally posted by amt
I noticed that the worksheet for the Fe167 + Alpha 15 is gone. Sadly, I forgot to save the pdf file. So I checked Martins website to see if it might be there and I see he has tried the Alphas and likes them better than the more expensive Daytons! Great!
Im thinking of using just a single Alpha with my Fe166ESRs and the Behringer. Wonder if the baffle could be made just taller to accomodate two Alphas if I decided to go that route? Martins baffle is way too big for my room. Im guessing that the higher Qts would allow the narrower baffle.
amt |
Hi,
Yeah, I'm curious about this too. Could be awesome.
And perhaps one could put wings on a narrower baffle, not parallel, to restore bass to a narrower design?
What do you think, Martin?
And could you give us an update/summary on your Project 7? How do you think it's oveall sound compares to your other projects? Do you like it? Do you recommend it?
Thanks!
George |
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