My first Open Baffle Speaker

[Telstar]

Originally posted by audiojoy
the spare cut out is for the second equivalent driver to get a 16ohm look in for the amp.

Well, you made a nice clone of the Bastanis Atlas

Looking for measurement results.

[audiojoy]

Yes it is a Bastanis clone, that is why I wrote in the first post :-

'where have we heard all this before'

I got a ticking off for mentioning manufacturer names in the past so i was careful this time to avoid it, but seeing as you have brought it up...

I am not sure how well I have mimicked the tweeter but it is sort of dipole and the 12" drive unit is from the same manufacturer and does have the same chassis. Not sure if the beta 12 LF is closer to the original, I am just waiting for a pair now to try. The original Bastanis driver has no whizzer but is capable of getting to 12k. Most of the Eminence 12" drivers reach 5k max without the use of coax driver or whizzer. I thought he might have extended the frequency with violin oils and baking. Mr Bastanis clearly stated on his forum that adding these sorts of 'potions' to the outer perimeter in a FEW FINE LAYERS (clearly not to be over done)and then again at an inner circumference was very beneficial to the sound. Also again following Mr Bastanis's advice, the use of pads near the driver certainly smooths the sound response I get. Adding 6 makes the sound over woolly, about 4 seems to be the optimum. It takes away edginess and sibilance from the midrange/upper frequencies.

The Beyma is very good. It integrates so well and is so unobtrusive in the overall picture. you would not know it was there. It is very smooth all the way.

My only reservation at present for this set up, as very good as it is, is that I still crave for a little more air more finer detail and better sound staging that i am use to.

Perhaps I need to burn in for a week or so still.

Anyone offer any other ideas, assuming the ancillaries are up to scratch

[Telstar]

Originally posted by audiojoy

My only reservation at present for this set up, as very good as it is, is that I still crave for a little more air more finer detail and better sound staging that i am use to.

I have one question, which also came to my mind after listening to the original Atlas speakers.

Is the soundstage of right proportions or is it too big/not much at focus?

Good to know about the Beyma tweeter, I think that they make excellent drivers.

[Ang]

I'm curious of about the rear radiation of the cp380 - is it attenuated in any way? Thanks.

[TrueSound]

Originally posted by audiojoy

My only reservation at present for this set up, as very good as it is, is that I still crave for a little more air more finer detail and better sound staging that i am use to.

Perhaps I need to burn in for a week or so still.

Anyone offer any other ideas, assuming the ancillaries are up to scratch

A 2uf cap and 12r 10 watt resistor series eq will do wonders.

[skorpion]

Yes, you should not overinterpret the Bastanis. They are based on OEM likening the 12CX, as far as guesses are, but more we don't know. It is probably a true OEM.

Better to do your own research, I suppose when you talk of 12"LF it is the 12" LTA you mean if carrying a whizzer.

I agree about measurement raised earier.

/Erling

[audiojoy]

Telstart

you are right there is a large picture in front of you as it were. But not knowing the full effect of microphones on the sound it is difficult to be use how realistic or unrealistic this is with certain recordings. If it of any help my stacked Quad esl 57 have almost the same size of imagery but had depth that extended backwards several meters and just gave voices and instruments that bit more dimension and air around them. I personally have not found a problem with focus at all it is more sound stage depth that is shallow. Width and height feels very real. I am sorry but i can only be subjective here in my description.

ANG i will replace the metal cap shortly to see if there has been any attenuation.

Truesound thanks for that will try it over the weekend.

[audiojoy]

Skorpion

the beta 12 appears to have had many iterations. There is the coaxial version (if i have interpreted correctly the Bastanis does not use coaxials according to their own literature) there is the version with the whizzer cone which I have used (sorry it is the LTA) and there is the version i am awaiting arrival of which has been given various titles over the years. In the USA it is titled as the 12A, in the UK i only have a model number for it EM124D1.Nonetheless still very cheap and £40 each.

I will research myself into the best driver, but I am assuming rightly or wrongly that BAstanis has already chosen the best woofer for the job. No harm in experimenting. I have also acquired a delta 12" pro which Bastanis definitely have not used,as it has a completely different chassis and technical specs are different also. But as each one of these speakers cost about a tenth of the BAstanis woofers there is no harm in purchasing several and checking out which is the best sounding one. Hey at £30 each the LTA sounds closer to the Quads than you could imagine.

Trying to get measurements is gonna take time to get my brain round the software etc. Is there no one machine with a microphone and screen with a chart to show the frequency response?? If there is the price will more than likely be prohibitive???

[SimontY]

Hi audiojoy,

Looks like an interesting project. I too recently got interested in dipole speakers. My fist set use a cheap Wharfedale tweeter, 4" Audax poly mid, and 4x 7" OEM 5.1 "sub" drivers and this, after much tweaking, is extremely musical and detailed. The same top and mid drivers in a box aren't very detailed or interesting!

You will find on this forum that unless you measure things the regulars won't have much to say.

I did much of my design with no measurements, but got frustrated when I reached a certain ceiling that I couldn't guess my way out of. I used ARTA (free to download) and the kit pre-amp and an electret capsule from http://www.madaboutsound.com/ to do some crude measurements. This enabled me to see that my ears made the crossover region quite smooth but had the tweeter way too loud. I had to make big changes and when I did, the sound got a lot better!! I then made it flatter still and the sound got worse, so I had to go back to the ears. Using both tools is now the only way for me.

For my next speaker project (work in progress - 3 way open baffle with Eminence and Skytronic) I will be attempting to use more sophisticated software and individual driver responses to assist the design work. Of course the ears must have the final say. The project is about my ultimate sound, not the frequency response, which is only one aspect of reproduction.

How are those Peerless woofers working out for you? It's certainly not how I'd tackle the bass (can't afford to), but Linkwitz likes them, and round here he's pretty much Gandalf/God.

Simon

[SimontY]

Originally posted by audiojoy
Trying to get measurements is gonna take time to get my brain round the software etc. Is there no one machine with a microphone and screen with a chart to show the frequency response?? If there is the price will more than likely be prohibitive???

I'd also love this if it existed, but I think getting onto the learning curve is probably the only way. Download ARTA, get a flat microphone (like the one on the site I linked to) and build that kit or get a preamp. Before doing this I bought a measurement mic and it was DOA. This is apparently common for the Behringer ECM8000 so don't waste your money. The capsule will do the same or a better job for peanuts. It needs soldering to a bit of coax or something - this is as good a stand as you need and avoids reflections.

The next step is to work out how to make ARTA show something on the screen. This can take very little work! First make sure you get some sound from your mic (turn pre-amp on, speak into it etc.), have a flick through the ARTA help, and mess about till something happens. It doesn't even need calibrating to get you started. A laptop with built-in sound is best avoided due to super-high noise, which will probably muddy your graphs badly. I just use my PC, which is very quiet and gets the job done.

Truly user-friendly software for this may exist, but I haven't heard of any. The industry standard software is LEAP and CLIO, I believe. These are VERY expensive, and I think if one looked, they might find it hard to come across an illicit copy, so it's probably best to stick to the free stuff to begin with.

Simon