Getting really close, I ended up with the first driver selection being the following:
Epique E220CF-8 8" from Parts Express for 169 each (had to try them at that price)
MarkAudio tweeters - supposed to close to or better than the Dynaudio tweeters
KEF B139 found an original set in perfect condition on eBay for $100
I am going with a very simple 2-way crossover, caps and inductors
I have stayed with the idea of a removable faceplate to make swapping drivers easier if I wanted to try another set. I ended up making new mounting plates for the tweeters to closer match the original SF tweeters 6" diameter.
I hope to wrap the faceplate in black leather and have it mounted this weekend.
Walnut side panels ($220 in the wood just for the walnut panels!), I have to do all of the routing for the glue joints Saturday and hope to get them glued up this weekend
Trying to make so experimenting with different drivers, crossovers, acoustic foam, etcetera will be fairly easy and accessible. This will include routing for rubber o-ring and foam seals for the side panels to be removable (hopefully)
I will try to get some photos this weekend and post them.
A couple of photos of the face plates wrapped in black leather, the carbon fiber plates I made for to replace the smaller diameter plates on the tweeters. As you can see I still have some work to finish the holes for the drivers. This weekend I finished gluing the walnut side panels and planned them smooth. It has been slow going with the weather, it has either been raining or snowing here and there is no way I am cutting and sanding in my garage/ listening room!
Hi Lojzek,
what makes you think that the Sine Cap Filter does not allow to develop the full potential? By the way, I prefer to name that filter topology as Inductive Highpass and am using it with good results. Of course, many ways lead to Rome... and of course, this is by far no universal filter method, it will work only in a few circumstances and with matching drivers.
All the best
Mattes
Here is a discussion of a recent design by Troels Gravesen that uses a similar crossover to the one in the Extrema.
Alex
Hi Mattes,
drive units need to be controlled by the crossover filter and they can not do that on their own. They can make sound even with a sine cap filter but suboptimally. Imagine a Porsche 968, only without original gearbox.
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Hi Alex,
thanks for the hint, I was aware of that discussion, but it´s a bit fruitless. I was very interested in same because I did build an inductive highpass filter recently and compared it with other more "classical" approaches of the same order.
However, I didn´t felt there was much interest.
Hi Lojzek,
why do you think the inductive highpass won´t control the driver? It is comparable with a first order highpass, including a parallel LCR at drivers rf. And that gives the rule of thumb for this filter topology, the driver must be several dB louder than it´s partner(s), should work on low-order filters, and last but not least the amp must be able to cope with low impedances, this is nothing for a SET.
That´s what I was trying to hint about in my former post, part of the magic of the Extrema were their drivers and this filter topology. The T 330 of the originals was fine for this filter, but the TO´s driver choice is most possibly not, and he should be aware of the issues with designing a good filter.
All the best
Mattes
thanks for the hint, I was aware of that discussion, but it´s a bit fruitless. I was very interested in same because I did build an inductive highpass filter recently and compared it with other more "classical" approaches of the same order.
However, I didn´t felt there was much interest.
Hi Lojzek,
why do you think the inductive highpass won´t control the driver? It is comparable with a first order highpass, including a parallel LCR at drivers rf. And that gives the rule of thumb for this filter topology, the driver must be several dB louder than it´s partner(s), should work on low-order filters, and last but not least the amp must be able to cope with low impedances, this is nothing for a SET.
That´s what I was trying to hint about in my former post, part of the magic of the Extrema were their drivers and this filter topology. The T 330 of the originals was fine for this filter, but the TO´s driver choice is most possibly not, and he should be aware of the issues with designing a good filter.
All the best
Mattes
Almost complete
Just a few photos. Took the week off to do a few things around the house, of course the speakers are taking priority!
Just a few photos. Took the week off to do a few things around the house, of course the speakers are taking priority!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
Trying to solder and assemble today, with any luck I will finish by this evening and be able to take a break from them and work on a couple cars tomorrow.
I am going with a very simple 2 way cross-over for now, I still have to see how the drivers will perform in the enclosure. Keeping my fingers crossed!
I am going with a very simple 2 way cross-over for now, I still have to see how the drivers will perform in the enclosure. Keeping my fingers crossed!
