In Reply to: More pictures Midwest Audiofest posted by bmar on March 31, 2002 at 19:45:46:
I couldn't make the Midwest Audiofest and neither could Greg R. So since we were feeling "all left out," we decided to have our own little Mini-Midwest Audiofest today, here in Tulsa. Actually, since there was only two of us and the event in Lima had over 200, maybe ours was more like a "Micro" than a "Mini-Audiofest." [grin]Seriously, Greg and I had planned to get together as soon as I was finished working this weekend, and tenatively planned on Easter Sunday at 3pm. He brought a pair of Bottlehead Paraglow monoblocks and some other odds and ends, including a passive switcher/attenuator ("preamp") and an active crossover of his own design. This crossover has the same filter characteristics as are used in the π two-way passive crossovers, so there is augmentation of the top octave for his Altec 511 horns.
I had hoped to get my first listen of a Bottlehead amplifier with a pair of Theater Series four π Speakers, to hear for myself "what all the fuss is about." Well, I'm pleased to report that now I have, and I understand why this combination is so popular.
Theater Series four π Speaker
The speakers we used were those I recently built for Sean O, and I wanted to hear them just as shipped, so we connected the Bottlehead amp to them, just using a CD player through the passive attenuator/switcher for input. There were no sound modifiers or tone controls present, and the active crossover was not used.
Bottlehead Paraglow's on each side of the oscilloscope
Greg did an excellent job building his Paraglows. They are attractive, and they are well built. They did not hum much at all, and what hum was present was barely audible. Greg got excited because he said in his home, they hum even less - Apparently something about the conditions in my house made his system hum a little - Probably all the 60hz I've got running everywhere to power up high current devices. But to tell the truth, you had to stick your head near the woofer to hear it, and that's really, really great considering the four π Speakers we connected to are 101dB speakers.
To tell the truth, I was impressed because the system sounds just like good semiconductor amps, when used at very low volume. Some of you may consider this statement heretical, and many of you may wince. But I had expected maybe just a small bit of attenuation in the bottom and top frequency extremes, and none was found. As I said, the amplifier sounded just like an expensive bipolar amp to my ears.
Now before you "tube guys" jump all over me, consider the source. I meant that in respect, and it is intended as a compliment. I expected tube amps to be finicky and twitchy. I thought you'd turn 'em on and wait for a minute, then get sound which constantly changed over the next ten minutes. I expected that they would color the sound to be "warm," which really meant they had slightly bloated bass with noticable midrange distortion. But what I found was that after the system powered up, these things sounded just like a good transistor amp. Nothing weird, no "twitchyness." There is more distortion, but it isn't audible. The two technologies sounded just alike to my ears, up to 2 watts. Again, to me, that's saying something. If two things are frequency linear and each distorts very, very little - they should sound alike!
We had the scope out really just for fun. Had it making Lissajous patterns with the music, and you can see one on the screen although it is barely visible in the photograph. We got it out to demonstrate the difference in a tube amp at clipping - And it had the tell-tale rounded corners. I noticed that this particular amp was biased slightly further positive because it clipped at approximately 6 volts on the positive half cycle, and wasn't clipping on the negative half yet. That would have put it at 4.24 volts RMS, which then corresponds to about 2.25 watts RMS. That's not a lot of power, but Greg and I had to yell if we wanted to talk over the music, which we rarely did.
We listened to a variety of music including Yes, Verve Pipe, and even Glenn Miller and Tool. Quite a selection, huh? In each case, the system sounded great. It actually just sounded "right." Nothing other-worldly special, nor anything weird or bad. To tell the truth, that's my definition of accuracy: It doesn't add anything and it doesn't take anything away. It's boring, really - No magic, no surprises. It's just natural, and that's all. And that's how this system sounded.
Greg R. and his active crossover
Greg shows his active crossovers with top-octave compensation for his Altec 511's.
Wayne and Greg, at our own little Tulsa Midwest Mini-Audiofest
All-in-all, I'm anxious to build a pair of Paramour or Paraglow monoblocks. They sound very nice, and when combined with 100dB+ speakers, the volume is sufficient. Now I've finally been able to hear what all of you guys running four π Speakers and Paramour amplifiers are excited about!
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