Help needed! Where to start with open baffle speakers

[vintage60]

Hi All

I've been inspired by a hifi friend of mine (Dave) to start my first "own build" hifi. Unlike me, he has been building his own speakers and turntables since he was 16 and is now an old hand. He's given me some pointers, but his plans and tech specs are too advanced for me.

I'm looking to build my own open baffle speakers with the help of 3 other hifi friends. All are called Dave (yes, it gets very confusing when 4 of your closest hifi pals are all called Dave) and all 3 are in the hifi/music business. None of us though have experience of building speakers. One is a guitarist in a band and repairs guitars, the second fixes amplifiers, turntables and CD players and the third fixes keyboards. I break things more often than fixing them so they will be doing most of the work.

So, there's our background and we motley crew are, at my instigation, tooled up to build our (I mean mine) first set of speakers and I have chosen to go down the open baffle route.

Do any AoS members have experience of building their own open baffles from scratch? I'm not looking to buy a kit and put it together - that's for wimps.

Any plans, pointers, useful websites to get data points/tech information and recommendations for woofers and tweeters would be gratefully received. I've seen a useful article on the Enjoy the Music website, but it does not have any pictures or plans and also some other articles - 6 Moons etc. I would like to start with a relatively simple and straightforward design please....I'm not up for trying to turn an abandoned old rowing boat into OBs.

Thanks in advance for any help anyone can give me.

[paulf-2007]

Audio circle have a dedicated section on open baffles, hundreds of threads. I have built open baffles with various drivers, lowthers being one with 15" eminence alpha bass drivers. I found making an open backed box for the bass was better. It's very easy to get good results with little knowledge. Trial and error is fun but audio circle will help.

[Infinitely Baffled]

These:
http://jelabsarch.blogspot.co.uk/201...en-baffle.html
are absurdly easy to build, and you wouldn't belive how good they sound! They look sort of cool too in a nerdy, ironic kind of way.
IB

[fatmarley]

If I were to build an open baffle speaker It would probably be this - OBL-15

What I wouldn't do Is use ONLY my ears to design the crossover. Lots of open baffle speaker designers do this, the frequency response will be all over the place and half your CD's will now be "recorded badly". Lampizator Is probably the most famous guy for designing crossovers In this way.

Troels reverse engineers the Lampizator P17 somewhere here - P17

[RothwellAudio]

I'm not entirely sure what it is you want to know. Open baffle speakers are simply speakers on an open baffle instead of a box. The advantage is no boxiness and the disadvantage is reduced bass. The bigger the baffle, the closer they come to "infinite baffle" - which is the same as an extremely large box.
Whether to use a wide-range single driver or a two way or three way setup and how to design a suitable crossover are decisions/problems which are common to any loudspeaker design, not just open baffle.

Do you want to start completely from scratch with your own design or do you want to go with someone else's tried-and-tested design? Being an old cynic I'm wary of the thousands of speaker designs on the internet which all claim to deliver sound so fantastic that it's a revelation, though I'm sure lots of them are very good. But how do you tell which are the good ones?

This guy's website certainly looks impressive and he convinces me he knows what he's talking about:
http://www.troelsgravesen.dk/Diy_Lou...r_Projects.htm
A lot of his designs use expensive drivers and wouldn't be cheap to make, and most of his site is dedicated to reflex speakers, but there's some stuff about open baffles and lots of info about speakers in general.

My advice is to read as much as you can to build your knowledge base before you build your first speakers.

[walpurgis]

Being an old cynic I'm wary of the thousands of speaker designs on the internet which all claim to deliver sound so fantastic that it's a revelation

I agree.

If you have no experience of speaker building, start with something simple.

[vintage60]

Geoff - you are spot on. I want to start with something simple.

Andrew - you raise some very pertinent points. Its precisely because there are so many claims on the internet about peoples' designs being fabulous that I don't know where to start.

So I'm looking for an AoS member who has built his own OB that sounds nice or knows of a design which they have experienced which is positive. So yes, tried and tested would be great. I'm not looking for a revelation or absolute best since I don't believe in absolutes in HiFi.

In case it is relevant, I'm looking for a design that will work in a room that measures 18ft x 25ft although due to the design of the room, I'll be sitting around 12ft from the speakers. I have no problem giving them plenty of space behind as well as sides.

Soundwise, I am not a bass head so whilst bass is important, I'm not looking for something that will knock down the walls. Most important for me is a sweet and smooth midrange. I'm quite sensitive to high frequencies and find most modern speakers are too forward with their upper mids and highs which quickly becomes fatiguing to my ears. The best way I can describe the sound that I like is to say that I like the Harbeth sound, although I'm not trying to replicate a thin wall closed box design with an OB design. Just saying that neutrality, tonal balance, well controlled bass and honesty are my priorities.

So with that, any pointers as to woofers (how many should I have/make/size), tweeters, cross overs, size, shape etc., would be much appreciated.

I'll do research over the next few weeks to build my knowledge base.

Thanks all

[walpurgis]

Take a look at Fostex full range drivers. These are high quality speaker units. Wilmslow Audio stock a wide range and can probably advise on baffle or cabinet design.

http://www.wilmslow-audio.co.uk/fostex-56-c.asp

[paulf-2007]

Eminence alpha 15a are reasonably priced and sound very good. Something I learned from others on audio circle is to brace the drivers frame on the magnet, it gives cleaner sound up to 350hz, whereas without the bracing only to 200hz. Depending on which wide range driver you use with it will depend whether the bracing is needed, but then it may as well be done anyway.

[Ali Tait]

The Beta is better than the Alpha for OB. I'd use a pair of Betas per side up to 200hz, then cross over to something like Alpair 12P as in the below thread, or Visaton B200 is also a good choice.

Good info here-

http://www.audio-talk.co.uk/phpBB3/v...php?f=4&t=6916

I run my OB's actively, see thread here-

http://theartofsound.net/forum/showt...OB-Experiments