Upon finding out that Ascendant has NOT discontinued the Poly 6.5's (or is at least still selling them), I decided to start looking at what I'm going to use for my 2nd DIY project, which I intend to use for some time.
A nice combination seems to be the Vifa D26NC55 and Ascendant Audio Poly 6.5.
Ascendant Audio frequency response graph
Ascendant Audio Poly 6.5 distortion graph
D26NC55 frequency response graph
D26NC55 distortion graph
From what I can see, the 6.5 should do fine crossed over to the D26 at 2.5khz. I'm pretty new at designing crossovers, but it seems that the D26 is almost entirely flat in its response curve with only a high pass filter at about 17khz. The woofer should result in a F3 of about 43hz in a 19 liter sealed box, which is not too bad at all.
Also nice is the price - $122 total - for the drivers. A pair could easily be built for $150 total, which is not a bad price at all, and in a small room these could sound very good indeed.
A nice combination seems to be the Vifa D26NC55 and Ascendant Audio Poly 6.5.
Ascendant Audio frequency response graph
Ascendant Audio Poly 6.5 distortion graph
D26NC55 frequency response graph
D26NC55 distortion graph
From what I can see, the 6.5 should do fine crossed over to the D26 at 2.5khz. I'm pretty new at designing crossovers, but it seems that the D26 is almost entirely flat in its response curve with only a high pass filter at about 17khz. The woofer should result in a F3 of about 43hz in a 19 liter sealed box, which is not too bad at all.
Also nice is the price - $122 total - for the drivers. A pair could easily be built for $150 total, which is not a bad price at all, and in a small room these could sound very good indeed.
It sounds like an easy beginner's project, which is good. The poly cone doesn't have nasty breakup like a metal cone, and is probably even more benign than a paper cone.
Just be careful of that rising 3rd order distortion below 2 khz. A steep crossover will prevent that from being a problem, but you should also have a look at some of the Seas tweeters- for example the 27TDFC and the 27TBFCG. They're good for crossing low, and only cost a couple of dollars more. If it allows you to use a lower order crossover, then the upgrade would pay for itself.
Another thing- don't forget the baffle step compensation! I forgot that on my first project, and boy was that noticeable!
Just be careful of that rising 3rd order distortion below 2 khz. A steep crossover will prevent that from being a problem, but you should also have a look at some of the Seas tweeters- for example the 27TDFC and the 27TBFCG. They're good for crossing low, and only cost a couple of dollars more. If it allows you to use a lower order crossover, then the upgrade would pay for itself.
Another thing- don't forget the baffle step compensation! I forgot that on my first project, and boy was that noticeable!
joe carrow said:
I was considering an active crossover, so this may not be as hard as you think. (LM3875's are about $2.75 if you buy them as samples - woot!). The reason I chose the D26NC55 is not so much the lower price as the lower distortion than the 27TDFC - according to Zaph's charts, it's a decent bit better.
27TDFC distortion chart
D27NC55 distortion chart
Spasticteapot said:
If you can get your hands on those, that would make you special. I've heard from 3 others that can't. I have them marked as discontinued on my web site until I hear otherwise.
Perhaps the 6.5 polys will get picked up by a vendor and the supply will be more reliable, but who knows.
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