Oh, that's what you meant. It is still there on Kalemegdan fortress, the "Winner" monument. A few years ago, they reconstructed the plinth and monumet, it was about to collapse.
Not surprising. I have found most FRs i have listened to were mediocre at best. The Fostex i could lve with are few, and that after my tweaking them significantly.
There are some real gems and the provide stuff no typical multiway i have heard matches.
dave
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Might be worthwhile getting soething like a miniDSP even just to help determine the appropriate XO. And for XO below about 200 Hz a passive becomes very difficult if possible at all.
dave
I agree entirely. For the reasons you state. That IS the route I will take. But first I'm going to build the small FR unit that'll eventually go with the B139 - and something larger like the Coniston or a BIB (getting two designs from two 8'x4' sheets) and listen very carefully to the results - enjoying the entire process.
Mini DSP, as far as I've been following, some here on the local DIY audio forums have tried it. It's only useful for SUB, it spoils the sound for everything else. Too many AD/DA conversions with relatively cheap ICs.
I have two friends, both fans of Fostex drivers. One has FE206 in MJ King MLTL and the other FE208EZ in Fostex horn. The sound is OK after correcting the baffle step and adding super tweeters. They lack a bit of bass for my taste. But both work nicely only with SE class A tube amplifiers. SS amplification is practically prohibited. 😏
If they read this they will probably be pissed, but my 3 way classic speakers with Vifa NE and Fountek drivers and a fat crossover work much better. 🤣
Fostex horn, there was a lot of work there. Only for the most persistent. 🙄
https://www.fostexinternational.com/docs/speaker_components/pdf/recom_enclose/208ez_enclrev.pdf
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I suggest you this, cheap and simple, no box, and you also have a few crossovers for different FR drivers. You have a big room, that's good for OB. Thanks to the large Qt, the Alpha 15A has enough bass even on an ordinary board like this. As for the final look, that already depends on you. The BD139 can't even come close to the OB Alpha 15A in sound quality, and not to mention efficiency. There is at least a 10dB difference. You can make a party with 2x20W amplifier.
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The combination of an expensive closed DSP box and a cheap low performance wideband driver is a pretty weird one. A Raspberry pi and perhaps one or two bits is likely to be cheaper and more useful if you are comfortable with computers and have a requirement for signal processing. I would suggest holding fire on planning to combine the wideband driver with anything else until after you have found out what a wideband driver is and what it can and cannot do. Most people that are interested in high fidelity sound in the home tended to be a bit baffled by the enthusiasm a few have for them. Perhaps you will gather enthusiasm for them but expecting it probably isn't wise.
I'm not that keen on DSP - but I can see the value of trying it for testing - and then building an active XO. Rod Elliot has PCBs for active XOs - and come to think about it - one with a variable XO point instead of the DSP.
I'm curious. I'll build a small cabinet and listen well. My expectations are non-existent. Put it this way - buying a pair of Eikonas at £600 as an experiment is not going to happen. £100-£200 for a pair of FRs and doing it properly is an experiment - particularly as I've never even heard a FR design.
What sparked my curiosity is the SIbelius speaker. People whos ears I respect like them a lot.
I advise you not to take FR speakers or any cone speakers with a metal diaphragm, except for subwoofer. Just look at the paper ones.
I think we might have our lines crossed somewhere. Why would you prefer an analogue active crossover over a more flexible, cheaper (subject to implementation), convenient digital one? Not saying there aren't reasons just that they aren't apparent to me.
That seems a bit expensive compared to a reasonable coaxial such as those from SB Acoustics at around £45-55 each. I would suggest wideband drivers for "proper" small budget speakers are more in the £10-20 range. Then again specialist low volume audiophile drivers are not going to be cheap. Be aware though that whatever driver you choose at whatever price you will be told by a fair few enthusiasts that you have bought the wrong one and that is why you are not hearing all the positives that wideband drivers bring to the reproduction of music.
Really? At £4.5k a pair they are competitive with a similarish sized speaker like a KEF LS60. No that isn't really a fair comparison since the KEF comes with amplifiers and a control unit. OK having fun with the hobby is what is most important but becoming too detached from reality is likely to risk longer term satisfaction.
We cut a boardroom table top in two and built those. A good starter project for one wanting to pursue OBs. Part of our journey towards abandoning OBs more or less completely.
dave
Metal speakers have a reputation, a stereotype. Peopel expect them to sound a certain way. And mostly they do. Mark, when he transitioned from thr Jordan inspired cones of the first generation Markadudio drivers, which had the same issues as the Jordans, to the second generation. This is particualrily as one goes from A10>A10.2>A10.3 each of which got better.
And then there was teh A7p. A paper cone that had the stereotype “metal sound” whereas the metal A7.3 is more like a paper cone.
Execution is important, the Markaudios (mostly) stand out and work hard to not be the sterotype.
dave
You could ask Nelson the same question. It was member demand that led to the LXmini and 6-24 XOs.
dave
Thanks for the reply. The miniDSP 2x4 in the list of parts for the LXmini seems to be a normal (these days) digital one rather than analogue. Bit surprised given Linkwitz was very much an analogue filter man and used analogue active filters in the Orion. I hadn't heard of the 6-24 which seems to be a rather audiophile analogue active crossover that appears even less flexible than a passive one. Is it expected that the user designs and adds circuitry or more stages to control the bumps and dips in the response or am I missing/misunderstanding something? Back in the 70s I "designed" an active crossover with op-amps (learning exercise using app-notes) for the inevitable T27+B110 pairing but it was hard work with not much satisfaction but then I guess we are all different. Abandoned the project before moving on to the circuitry for a sub. All that work to get an approximation to the desired transfer function or an afternoon designing and testing some digital filters to get the transfer function wanted? In truth I didn't know about spice at the time which would have been available at work and instead used a programmable calculator so perhaps not quite an apples to apples comparison.
@DartmoorDad mentioned that he was going to get a small FR driver and then add a B139 to it. I don't think it's a good idea because of the low power and efficiency of that old B139, and this OB from MJK is much better and simpler to build. And how it all sounds together I don't know, I know that Alfa 15A is a good bass for OB and quite cheap. A big advantage is greater efficiency and power, the crossover is known, has multiple FR drivers to choose from and does not have to make a box, a couple of boards and there are the speakers.
You start where you are, not from where you wish to be. If sounds cryptic it merely means I have two B139s and two T15s in cabinets that are falling apart (from a speaker that was never wonderful in the first place - Celeste K2) - and wish to make use of them in something better (and larger) than the original enclosure.
I could, possibly repair the cabinets with much glue and clamping and then give them more solidity with extra 5mm ply on the outside - they would still however be Celeste K2s. i could sell/give away the drivers - but these units were bought by my father in the mid-1960s and they have some sentimental value.
Ok now I remember. There I proposed rather inefficient FR drivers (2.5"-3") that roughly correspond to the B139, They are practically not FRs in the sense that they will quickly show problems if low frequencies are fed to them. They would practically work as a mid/tweeter and replace the T15 with the same or slightly lower cutoff frequency.
If you take a larger, more efficient FR, then B139 is not a good match. That's possible too, but the FR should be dampened a lot to match the B139. This will probably spoil the sound of the FR driver.
And now we are back to the beginning. I think you need to build a new box, refresh the crossover, replace damping material, and replace the wiring for the B139/T15 combination. To improve the sound more ,to get details and spaciousness, add some cheap super tweeter at the back, that's the simplest thing about those boxes. You can increase the volume of the box by increasing the depth while keeping the front side the same. And so you are left with a vintage speaker almost as it was, only with a better sound.
If you take a larger, more efficient FR, then B139 is not a good match. That's possible too, but the FR should be dampened a lot to match the B139. This will probably spoil the sound of the FR driver.
And now we are back to the beginning. I think you need to build a new box, refresh the crossover, replace damping material, and replace the wiring for the B139/T15 combination. To improve the sound more ,to get details and spaciousness, add some cheap super tweeter at the back, that's the simplest thing about those boxes. You can increase the volume of the box by increasing the depth while keeping the front side the same. And so you are left with a vintage speaker almost as it was, only with a better sound.
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