• To the Pictures!

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!

I had a riot with you guys. I finally have names on all the pictures now. Spelling I'll have to work on tomorrow. I think your 4 Pi's in Maple turned out great, and along with George's 4 Pi's. The Theater had some great musice going on.

The Dukane's sound great. no hum and way too much power! they arent single ended but they sound very nice.

Bill

The two watt Paraglow sounded really nice with the four π's. I expected a bit less bass from the combination, simply because we are going through a transformer, which has a very definite high-pass lower cutoff. But the parafeed arrangement definitely helps in this regard.

I also sort of expected to hear a bit muddier bass because of less damping. Even "tube friendly" speakers benefit from having a good current source, because circuit output impedance interacts with the voice coil to set Qes. Some speaker motors actually require better damping, but the ones I've listed as tube friendly don't need as much damping - the Studio, Thermionics and Theater Series four and sevens. But even these would benefit from a well damped current source.

And finally, I expected a bit of attenuation in the higher frequencies. This is also an area where the transformer sets the limit. A direct coupled amp can literally boast DC to megahertz range linearity, no problem. But a transformer is like a horn - It's tuned for a frequency range. I found midrange and treble to be nice sounding, with full extension and no artificial rolloff. The amplifier sounded very natural, more so than I expected.

There was one other thing I liked. The nastalgia. It's very much like the feeling I get when I listen to my favorite talk radio program on a radio that was built before the second world war. I can almost hear the engines burst into life on a B-25. I can imagine Glenn Miller playing at ballrooms with pretty ladies who still wear high heels and femine dresses. I visualize old round cars driving and no computers, no jet airplanes, no nuclear anything and no microwaves. No televisions. I see these things in my mind when the tubes start to glow and I imagine the current surging through them when I listen to the radio, here, now, more than 50 years later.

That same feeling comes over me anytime I power up a tube device. It is just something nastalgic, and it is sort of unique to this time. Most people have long ago thrown away anything with tubes (except the television picture tube) and they wonder why on earth you would want to have something that used one. So it's sort of unique, like an antique car, and it's just retro and cool.

So that's the long version of how I felt. I loved it. I always listen to talk radio with my Stewart Warner tube radio. I could listen on any other radio, from my AM radio in my large stereo to a few little pocket radios I have around the house. All of these radios gets pressed into service at one time or another - One is a shortwave that I enjoy listening to pretty often. Another is used when I'm in the garage working on my car. But most of the time, when I listen to Art Bell in the evenings, I switch on the Stewart Warner. I'm enchanted by the glow.

well well, where to begin. My experiences are easy to sum up;
I'm obviously DEAF! While at Lima I had the oportunity to hear some of the best systems available today. Built with horns and tubes.
For my money the Pi speakers are on top. I heard differences when speakers were changed on amps. but when amps were changed on the same speakers, I'm sorry to say that within few minutes I cant hear much difference if any. There was one time in particular though, when a 300B amp was changed out for a pair of 45's. A tremendous difference in that case. Was it the 45 tube or the way that particular amp was made? I couldnt say. Before the 300B's were put into service there was a different amp. on that change over I didnt notice anything.

So why did I get a tube amp you ask? Nastalgia my friend. They are not single ended, but there is a lot of them and they look great! after only a few nights listening I cant notice any difference. Mind you i'm using my Denon as a preamp because I dont have not a tube preamp yet. So, right now the push pull Dukane amps sound like the Denon, but I get to heat up my living room and have a litle candle light to read by!

I cant sit on my couch and listen to talk radio. Like you though, I can sit and listen to talk radio on one of my old tube radio's all night, and often do!

This is a Hobby for me so when I build my own 300B or 2A3's some day, perhaps after having it in my listening room for an extended period of time, as oposed to stopping by for a quick listen, I too will be able to hear some more of these subtle differences.

And now that I'm begining to turn this hobby into more of an adventure by starting to make wooden horns. I listen a little more carefully to all the sounds that are there, and all the sounds that I thought were there before that last change. That kind of listening is different from sitting back and enjoying though. I find a difference between critically listening to the machines, and just sitting back.

As for the Denon? a component sytem was out of my budget and to be perfectly honest. I love to listen to the movie sound tracks during the films and it was time for an HT upgrade. I get to relax with a movie and listen to great songs, nice dialogue and special effects all at the same time. The denon was my choice over a half dozen other receivers I gave a listen to. a couple I noticed some differences, and others I heard no change, but this one just won out. The pro audio stuff I have is older and good for jamming, but I have hum and noise with my older stuff and rack gear was not going to be popular with the wife in the living room!

I like it all! Home theater, Well crafted tube gear, CD's, Vynal, High efficiency speakers.
why hell, I even get a charge out of electrostatics!

Bill

One thing that always catches my attention is where the volume knob is set. That's kind of stupid - it's a simple voltage divider and a couple of one cent resistors could set the divider to any level I wish. But I always notice whether the designer set the system so that full volume is just under or over clipping, as opposed to systems that enter clipping where the volume knobs are set at half of their movement scale. Just a little thing, but I hate it when you are into clipping before the knob has gone halfway through its movement.

Bill