How good can D.I.Y speakers really get? - Enter Mr Al Newall

Hi All,
Those speakers look great Steve, maybe a little pricey for me at the moment. You guys know an awful lot on this forum, so i wanted to ask a few questions about OB speakers.
The only large driver speakers i have heard recently were really expensive, with fancy tweeters powered by expensive amps. I love the bass slam and extension with a walk around sound stage, i guess this is what i am trying to recreate on a budget. I am hoping to buy a Chinese SET to power them. Would speakers like Al's do this in my room? Or should i be looking at a different DIY design?
I read the OB articles in HFW and i'm a little unsure if they will suit my room.
My room is only 14ft X 12ft 9ft ceiling, with speakers against the rear wall and 3ft from side walls. I have put some pics in the gallery to give you an idea.
I am really enjoying tapping you lot for answers, i do feel like a bit of a leech asking all these questions. But i have totally given up going to dealers, the last time i set foot in one and told them i was using valves and vinyl "why would you do that, your missing so much resolution" Final straw, DIY all the way!
Cheers
Ian

Ian, there are no straight answers, bigger rooms/ smaller rooms /expensive drivers/cheap drivers
with drivers and rooms.. bigger is better for bass
but that should not put you off a little diy in the open baffle dept

baffles are cheap and easy to make and you can play to your hearts content and if you dont get on with them you can usually recoup your outlay..
peter comeau's hi fi world open baffle ramblings where inspired after listening to my speakers at a diy meet.. he had not liked baffles until that point as far as know.. and he is stuggling to replicate mine, as some of my speakers used are vintage types and modern speakers are not the same.. without spending alot of money
there are various of schools of thought with open baffles, and always some comprimises.. as with all speakers?

the emmience drivers are a good and cost effective way of building open baffle speakers..
a 15"er.. linked with a full ranger of approprate quality and effeciency can provide very good results.. Al's are a prime example

i dont know where you are based but there will be quite a few speakers at our diy meet in june over on the audio-talk forum, you can get much more of a handle on what they do sound wise
i would forget the chinese amps...unless your a competent repairer they all seem to need sorting in some way

if you can wire a plug, use/own a multimeter and solder.. (that was my level before i built my first valve amp...) i would say building a wd kel84 is a much better bet.. and you will learn how easy valve amps are to build..

the main issues with baffles is the ability to move enough air in the bass..

most that build open baffles use the higher efficiency drivers, these have less forward and backwards cone movement, which is fine except in the bass, where they dont move enough air, coupled with the fact that part of the sound wave is cancelled due to the baffle

so there are a few choices.. to live with less bass, to add extra higher efficiency bass drivers( thats sort of been my way with a 12" and 15" per channel), add some form of Eq , or to add a seperate amp to a lower eff bass speaker..to bring the bass volume up.
the issue with the last method is a low eff driver is used, it sounds fine on its own but the higher effeciency mid/ treble unit will show its lack of quality up...
steve has got over that by using a reasonably efficient bass unit and a seperate amp
i too am looking forwards to hearing steve's at our next get together.

the real skill for building open baffles is in selecting the drivers, getting that right can make things easy so using a known combination is a real advantage..

hope thats some use
steve

Ian.

The Eminence Beta drivers at Maplins seem to be the same, they might have changed the colour on the back.
Mine are Beta 15A 8ohms and the specs look to be the same, though the price has taken a bit of a hike. You might find them cheaper elsewhere.

Whereabouts in the world are you?

I drive mine with 4-5 single ended watts, but as Marco will testify, they respond well to a bit more power.
Mine fold up so they fit neatly in a space against the wall when not in use, but i drag em out into the room a bit for listening.
I can't remember the last time i set foot in a dealers showroom, maybe i bought some phono plugs or something before Maplins arrived in Chester.
Don't look back.:)

Ian

Looking at the size of your room, you would do well to use a bass driver with a lower Q. The Eminence Beta 15 has a total Q of around 0.5. My Delta 12s have a Q of 0.45.

The reason for this is that they will roll of rapidly below resonance; not ideal in a larger room, but absolutely spot on for a small room. You compensate for the rapid roll off at the bottom by placing the baffles closer to the wall to get a bit of room gain.

Mine are about 2 feet out from the rear wall of my room, they go low and more importantly, do not set up room boom. Something like the Eminence Alpha 15 with its Q of 1.26 would have been awful in a small room.

Mine use active bass only because I had two plate amps available by cannibalising my old pair of subwoofers. Delta 12 8 ohm bass drivers have big magnets, so they are well damped in themselves. The plate amps therefore have no trouble controlling the cones in free-air, giving a tight, firm and fast foundation below the Goodmans full ranger and the Fostex HF driver. In other words they can keep up with the main drive units without slowing things down. The bass units are 98dB/W efficient so they match the efficiency of the Goodmans driver.

As Steve has hinted, a low efficiency driver on bass duties would have compromised the bass performance to an unnaceptable degree.

In a large room, my baffles might very well sound bass light. I haven't yet tried them in such a space, so the next meet will be interesting.

Steve

Thanks al & Steve for your replies. The first thing about Al's design was the cost, but if they are not suitable then i should put the money elsewhere. I was looking around on other uk hifi forums recently and did see mentioned some horn loaded speakers, i think fostex based. But i have gone dizzy looking for it again. I think Al's were at the same meet, any ideas? Thank you for inviting me up, i would love to come, but i just sold my car and South east London might be too far to hitch! Are there any meets around London?
I am really itching to build some speakers that will kick commercial butt and not cost a fortune, so any more suggestions would be gratefully received.
I am currently running some cheap Chinese valve amps, so i am aware of their shortcomings. I heard some expensive SET's at an audio jumble and loved the sound, so trying to get close on a budget.
Thanks again
Ian

Once I get mine up and running you are more than welcome to hear mine

Thanks John and other Steve,
I just asked the other half for the go ahead, Yes!
I found the Eminence Beta 15 for £45, so will order them tomorrow, Should i pay a little extra for the Audio Nirvana super 8 or stick with the Standard? Gonna ask my mate in the states tomorrow to order them for me.
Really looking forward to building these, so any more tips?
Cheers
Ian

Ian.

The Super 8 is apparently more up front sounding, which is perhaps better if you have a heavily carpetted and well furnished room. The STD 8 is fine for me because i have wooden flooring.
Having not compared the Super 8, it's difficult for me to judge either way.

If you have any reservations you can contact David Dicks at Commonsense Audio. He was quick in responding to my questions.
Either way the drivers will take a few hours to loosen up, before you hear what they can do.

Tip.
Once you have ordered the drivers, get everything else organised while you are waiting for delivery. Then it's just a matter of fitting them when they arrive.

Quote:

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I drive mine with 4-5 single ended watts, but as Marco will testify, they respond well to a bit more power.

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Err, just a little bit! Freakin' awesome on the end of 30W Class A valve power :fingers:

Ian, just build these speakers - it's a no-brainer!

Marco.

I would agree with Marco.

Looking at your room size on your system pics thread, Al's baffles with the Eminence Beta 15 bass units would be ideal for your room. You would not need to have them too far out from the rear wall (due to the the low Q I talked about) they would not intrude on the domestic environment and would sound awesome to boot!

As Marco says, it's a no-brainer.:)

Steve