If we were testing bare wires, I could slip it into test sessions. But unfortunately this is not the case.
The ideal measurement situation for certain purposes, that I can agree. But not ideal for finding a driver best for a particular horn design.
I am fully aware of the different sources and nature of distortion between drivers and amplifier. But there also exhibit some commonality. To lower THD is alway beneficial regardless, the issue with drivers is what source of distortion is more dominant in terms of listening impression. You always want to work on the more dominant ones first. The process is basically using different tests to figure out where the source of distortion is, and this is much more complicated in drivers than amplifiers.
Too bad a spiral wouldn't work. At least it could save a lot of room.
You can always go up, the sky is the limit.
Quite a bit of progress here on my "Beyond the Ariel" project.
My first goal was to try the GPA 416B and 515C woofers (alnico) in the upper woofer boxes, and see how each compares to the TD15M in this application. The GPA woofers have 16" frames, which made it necessary to recut the front baffles. This was completed on December 24.
I decided to try the 416's first. Since they have the same nominal impedance as the TD15M's, I was able to start out using the existing crossover. The results were stunning! It was an across-the-board improvement -- tone colors more beautiful and lifelike, and the transitions to the drivers above and below were much better than before.
At this point I was going without the ribbon tweeter (RAAL Lazy), but soon added it back in. Here the Slagle autoformer was very handy. The RAAL is sensitive enough to require significant attenuation. I ended up with it on the -9.5 dB tap, but might eventually drop it another notch. I'm using the 10-ohm tap on the RAAL.
After a few days of enjoyable listening, it was time to try the 515's. These have 16-ohm voice coils, so I had to revise the crossovers first. Once this was done, the results were somewhat less rewarding than it had been with the 416's, even thought the overall sound was excellent. Bass and lower miss were leaner, and the upper end of its range was less even.
These were fairly subtle issues that could certainly be worked around, but I couldn't get past the fact that the 416's were so musically satisfying from the very start. After a couple days of listening, I took everything apart, restored the original crossover circuit and reinstalled the 416's.
I now have a beautiful-sounding speaker system, and some leftover big woofers that need new homes!
Current configuration for each channel:
1. RAAL Lazy ribbon, 2nd order high pass at ~8 kHz, 10-ohm tap of tweeter connected to -9.5 dB tap on Slagle autoformer.
2. Radian 745NEO/Be (16 ohm) driver, Azurahorn AH425, 3rd order high pass at ~700 Hz, connected to -17.5 dB tap on Slagle autoformer with 35-ohm swamping resistor.
3. GPA 416-8B Classic Series (alnico), 3 cu ft sealed enclosure, 3rd order low pass at ~700 Hz, Zobel circuit, -3 dB at 61 Hz, attenuation-band notch filter at about 1,500 Hz.
4. AE TD15H-4 plus two AE PR15-700 passive radiators (1 on each side of cabinet), separately powered by plate amp.
Gary Dahl
My first goal was to try the GPA 416B and 515C woofers (alnico) in the upper woofer boxes, and see how each compares to the TD15M in this application. The GPA woofers have 16" frames, which made it necessary to recut the front baffles. This was completed on December 24.
I decided to try the 416's first. Since they have the same nominal impedance as the TD15M's, I was able to start out using the existing crossover. The results were stunning! It was an across-the-board improvement -- tone colors more beautiful and lifelike, and the transitions to the drivers above and below were much better than before.
At this point I was going without the ribbon tweeter (RAAL Lazy), but soon added it back in. Here the Slagle autoformer was very handy. The RAAL is sensitive enough to require significant attenuation. I ended up with it on the -9.5 dB tap, but might eventually drop it another notch. I'm using the 10-ohm tap on the RAAL.
After a few days of enjoyable listening, it was time to try the 515's. These have 16-ohm voice coils, so I had to revise the crossovers first. Once this was done, the results were somewhat less rewarding than it had been with the 416's, even thought the overall sound was excellent. Bass and lower miss were leaner, and the upper end of its range was less even.
These were fairly subtle issues that could certainly be worked around, but I couldn't get past the fact that the 416's were so musically satisfying from the very start. After a couple days of listening, I took everything apart, restored the original crossover circuit and reinstalled the 416's.
I now have a beautiful-sounding speaker system, and some leftover big woofers that need new homes!
Current configuration for each channel:
1. RAAL Lazy ribbon, 2nd order high pass at ~8 kHz, 10-ohm tap of tweeter connected to -9.5 dB tap on Slagle autoformer.
2. Radian 745NEO/Be (16 ohm) driver, Azurahorn AH425, 3rd order high pass at ~700 Hz, connected to -17.5 dB tap on Slagle autoformer with 35-ohm swamping resistor.
3. GPA 416-8B Classic Series (alnico), 3 cu ft sealed enclosure, 3rd order low pass at ~700 Hz, Zobel circuit, -3 dB at 61 Hz, attenuation-band notch filter at about 1,500 Hz.
4. AE TD15H-4 plus two AE PR15-700 passive radiators (1 on each side of cabinet), separately powered by plate amp.
Gary Dahl
Gary - thanks for the report. Interesting reading. I don't remember ever doing a direct 515 vs 416 comparison, do it's nice to hear what you thought. Also surprised that you got an F3 of 61Hz out of a 3 foot box. Not bad!
Now all we have to do it get you to try some Altec or GPA alnico 1.4" drivers on the horns.
Now all we have to do it get you to try some Altec or GPA alnico 1.4" drivers on the horns.
Thanks Scott!
The new system has what I call tonal weight and density, which makes for superb reproduction of piano. This was a weak area for the Ariel, and a goal I very much agreed with.
These speakers are in the same room with my treasured German-made Wilhelm Steinberg piano. I don't think it's realistic to expect that the two will ever sound exactly the same; their radiation patterns are profoundly different.
But the reproduction of piano is now a strength instead of a weakness. The 416 has made the biggest contribution to this.
Gary Dahl
That is a very worthy question, and I will need to do a lot more listening before I can give a satisfactory answer. I lived with the Ariels for many years, but the new speakers and I have just met! Not to dodge your question, I will give it some thought and come back to it when I can figure out how to express it.
BTW: It's Ariel, not Aerial. Lynn may have named the speaker after the main character in the classic Hans Christian Anderson story The Little Mermaid…or maybe he just liked the name.
These are Great Plains Audio (GPA) 515-16C Classic Series alnico woofers, and yes, they are available. Bill Hanuschak built them for me last month. They are brand new except for pre-conditioning on the sine wave generator, several rounds of TS testing and a couple days of listening. The cones are of current manufacture.
I'm also finished with the TD15M-8 Apollo woofers, and the GPA alnico 414-8B's. Lynn's pair of TD15M's are here as well, still unused. Not sure what he wants to do with them…for awhile I was planning to try two TD15M's in parallel on each side, but changed my mind.
Gary Dahl
Hi Peter,
No, I simply let the sealed enclosure do its part. I do think a high pass filter would be beneficial if I were using a resistive-vent enclosure as Lynn has suggested.
I really like the way the 416 sounds in a 3 cu ft sealed box, and am inclined to just let it be.
Gary Dahl
This combination of drivers, horns and enclosures does what I was hoping for. Eventually I will see what more can be done in fine-tuning and refinement in the crossover, but my plan is to leave them alone for awhile so I can become as familiar with the sound as possible, which will make it a lot easier to evaluate the effect of revisions in the future. At this time I will be turning my attention toward my amps and source components.
One exception: Lynn might send me his 745NEO/aluminum drivers to try, because the comparison would certainly be interesting.
Gary Dahl
Do you use damping materials in that sealed box? And if yes, what kind of materials? Just curious...