Don Richard

Opus One is good. Silver Oak, also. Whenever I drink a lot of either I think I can hear 40khz. Don Honk if you love Horns

I forgot C&W. Don Honk if you love Horns

Certainly sounds do exist above the range of human hearing. How can these sounds be recorded for playback? ACO 7016 mics into a 24/192 PROFESSIONAL grade recorder? Perhaps. Then how do you play it back? Well, a PROFESSIONAL grade 24/192 playback system would work. On the masters. Sample rate conversion to one of the home hifi standards will result in damaged information, and loss of this HF information. What loudspeaker can reproduce these frequencies? IIRC, JBL and a few manufacturers of nearfield studio monitors have models that go to 40khz or so. These units are used in PROFESSIONAL studio playback systems with 24/192 capability. They don't go to 110khz or higher. Who can hear all of this? Many studies contradict the one you mention. PWK ran his own experiments in the 70s where it was found that inserting a 30hz-20khz filter ahead of a wideband amplifier had no audible effect. If one listens to live blues, R&B, jazz, rock, techno, rap, or hip-hop, you are listening to amplified instruments and sound reinforced acoustic instruments. You are listening to loudspeakers. Loudspeakers that do not and cannot accurately reproduce 20khz much less anything higher. The study you cite miced the instrument under analysis at a close distance. HF is attenuated at a greater rate with increased distance and increasing frequencies. At long distances HF attenuation is severe at ultrasonic frequencies. At normal concert listening distances for acoustical events such as a symphony, these frequencies cannot be detected. They would have been diffused/absorbed/dissipated by that distance. But don't worry. I just read in a certain audiophile magazine that the proper $2200 speaker cables will solve these problems. [^o)] Right. Don Honk if you love Horns

Different sides of the same coin. But when it is time to decode the audio information, the ear acts like an FFT. Basically, the eardrum transmits the vibrations caused by sound pressure to the hair-like cells located in the cochlea which in turn stimulate the auditory nerve which in turn sends electrical impulses to the brain that causes the perception of a sound. If you "unwind" the snail-like structure of the cochlea the hair cells will then be in a straight line that matches closely with the logarithmic scale used to plot frequency response. Thats right, each "hair" in the ear structure corresponds to a specific frequency. There has to be a "hair" that can detect a frequency in order for it to be heard. You cannot divorce rise time in a waveform from the frequencies used to create the waveform. All audio waveforms are combinations of sine waves at various frequencies. So in order for us to hear a certain waveform the frequencies that make up that waveform have to be able to be detected by the ear mechanism. The human ear can detect frequencies from about 20hz-18khz. This is insufficient to recreate steep fronted waveforms exactly. Thats why an 8khz square wave sounds like an 8khz sine wave to humans, and thats why steeper rise times cannot be heard. Recorded sound does not include rise times anywhere near the steepness of an 8khz square wave. The microphones couldn't couldn't capture the information even if it were there, the electronics wouldn't pass it (its not there, remember), and the recorder couldn't capture it. Playback systems cannot reproduce the frequencies necessary to reconstruct an 8khz square wave. So putting a link in the audio chain that can recreate a square wave, or any waveform with a similarly steep rise time, just before a loudspeaker that has absolutely no chance of reproducing that waveform is superfluous. And you can't hear it anyway. People who operate, design, and manufacture professional audio equipment know all of this. That is why pro sound gear is bandwidth limited. These folks won't waste their time or money on things that make no difference in audible sound quality. Don Honk if you love Horns

I thought that would get you going[6] Now you're trying to get me going[:^)] The last time I heard a glockenspiel live it sounded exactly like a wind chime[] Don Honk if you love Horns

Well, low power tube amps were designed to feed efficient horn loaded theater speakers.[] But so are SR amps[] Don Honk if you love Horns

The "rules" were never changed. We hook our amps to speakers, then we listen through them to the speakers. You hear the speakers, hopefully not the amp. Vacuum tube power amps sound greatly different from each other when hooked to loudspeaker loads. That means you are hearing something that the amp is doing when it reacts to the load. So the amp is changing the sound. That is the definition of distortion. Distortion generated by the amp may be desirable during the creation of music. However, I am not going to ditch my XTIs and put Marshall guitar amps on my Khorns. No matter how good the square waves look. Hmmmmm... I wonder if the square wave shape on the tube amp output wasn't helped by the high amount of harmonic distortion created by the tuber? Don Honk if you love Horns

Unless it is an OTL design I bet it has to have a ton of NFB to go out to the 200KHZ plus that it would take to push an 8KHZ square wave through an output transformer. BTW, how many watts output from the tube unit? Don Honk if you love Horns

I thought that you listened to amps and looked at TVs. What source are you using? CDs, records, and tape won't reproduce the harmonics required to create an 8KHZ square wave. Square wave generators make for lousy listening. But you couldn't tell if the wave was square or sine by listening, anyway. Don Honk if you love Horns

Big difference in doing something intentionally versus an unintended consequence. Any amp that is bandwidth limited to 20-20KHZ will not reproduce a square wave properly. Most pro sound SR amps are designed that way. An 8 KHZ square wave and an 8 KHZ sine wave sound identical to humans. It takes odd harmonics of the fundamental sine wave frequency to make a square wave. The 3rd harmonic of 8KHZ is 24 KHZ. The 9th harmonic is 72KHZ. I can't hear that, neither can you or any other human. 20-20KHZ limited amps won't reproduce it either. Why would you want to? If you ran that same waveform into a tube amp the output display wouldn't look any better than the one from the pro amp, if that "good". A sine wave sweep, 20-20KHZ from a tube amp into a loudspeaker load, would look more like your square wave output than the +/- 1 dB flat line we are used to seeing from SS amps. There were many good reasons for the move away from tubes in power amps. Those reasons are still valid. Welcome to the 21st century, to those who have arrived. Don Honk if you love horns

I was traveling on I-10 somewhere in Texas a few years ago and saw a pile of 8 track tapes in a truck stop where I got gas. Somewhere between Houston and LaGrange. The cashier said a few of the truckers still used them and would come in and trade tapes there. Might be a source. Don Honk if you love horns

Vacuum tubes have an inherently high output impedance. In power amps this requires the use of an output transformer to match up to a low impedance speaker. So you wind up with a 4-16 ohm impedance-matched transmission line. With a loudspeaker that has a varying impedance curve (most of them) this will result in a widely varying frequency response curve. Output transformers limit frequency response and can affect the timbre of the sound due to the transformer's inductance, capacitance, and magnetic hystyresis. Tubes make perfect sense to me for use in preamps, the choice is less clear for using tubes in amps. Don Honk if you love horns

In the 70's PWK reported on distortion measurements taken with a spectrum analyzer on a loudspeaker described as "a loudspeaker designed so that a number of drivers in the rear of the cabinet reflected sound off of walls and surrounding objects". Modulation distortion was many times higher than results from a Heresy played at the same SPL. This was around the same time the famous yellow BULL**** button appeared. Nine lousy speakers placed in the same cabinet aren't going to sound better somehow. Just nine times lousier. Every Bose product I have ever heard could only be described as a crime against sound reproduction. The 901 is the worst. Don

Using these on vacuum tube gear should make such gear nearly immune to damage from surge and transients. Don

The Eminence driver that was used in the 70s-80s and used by Klipsch as the K-33 was a music instrument speaker and would work for a bass guitar in the proper cabinet. However, it would be more valuable as a K-33 to be used for replacement purposes in a Klipsch product. Other, better options exist for MI drivers. Don

That looks exactly like my AA xovers that I bought from Klipsch in the early 70's to replace the original type A network. Replace the caps at the least. Don

+1 on that! Don

Power surges and ground bounce transients usually do more damage passing through a power stage to components beyond than damage to the power supply itself. Spikes and switching transients create energy up in the 1-2 mhz range and are best filtered by RFI/EMI suppression where power enters the equipment before it is rectified. Once this HF energy gets into any equipment, all bets are off as to damage, with CMOS devices being the most sensitive to this sort of damage, other SS devices right behind. Crown has EMI filtration on the XTI's power input. I can't speak for the D45's power supply components, but it is not good to run 35V caps at 31V continuously on anything. Poor design, IMO. Vacuum tubes are inherently immune to spikes and surges - they are designed to operate at high voltage, and components are so rated. You never used to hear about power surges and surge damage or see surge protectors back then. Don

Hiss is the only problem that I have heard from the XTIs I have, and you have to be close to the HF horn to hear it. As far as resolving the details you mentioned, I'm hearing all of these things you mentioned now. The quality of the source and the loudspeaker have far more to do with the resolution of detail in a reproduction system than the amplification that is used. A poor room smears and ruins transient attacks to such a degree that any system is going to sound bad in that room, and any differences in amplification will be difficult to impossible to hear. Having a 275 W/Ch amp running 1/3 W simply means that it's running in class A nearly all of the time. Amplifiers may interact with the loudspeaker load, and preamplifiers may interact with the power amp. These interactions probably cause most of the differences heard in amplification equipment. Pro amplifiers are designed to drive difficult loads and to deliver massive output when called upon to do so. Pro equipment is designed to work any other equipment, balanced or unbalanced, with few interfacing problems. Pro equipment handles power surges and transients with less chance of damage or audible consequences. Pro amps aren't like nail guns, but rather like 16# mauls that can drive tacks. Don

What is minimum detail? As far as comparing other amps, I've compared the XTI to Crown's XLS, an old SAE MKII, and the amp section of a Mitsubishi reciever. The XLS and Mitsu receiver were quiet listening about a foot from the HF horn, the XTI has an audible hiss that close. The SAE had more hiss than the XTI. All of these amps sounded acceptably good, with little difference in audible quality when each was used on HF in a tri-amped configuration with amp outputs hooked directly to the voice coils.

On Jan.16, 2008 D Glass of Crown wrote: "However, to put it in a little different light the topology used in the XTi is based of the same AB+B topology used in the DC300 series amplifiers which was a home audiophile amplifier standard for years. The only real difference is that with newer technologies we are able to produce an amplifier with more power, that has better efficiency, weighs less and cost less." So a class AB amp with a DSP in front of it isn't good for audio? Or any DSP is no good? Or any AB SS amp is no good? Or only the ones that weigh less and cost less? Don

14 ga. stranded copper wire should be more than enough. Don

Correct. Absolutely never ever put square waves into a tweeter. He was sending about 1 watt @ 200 HZ into full range speakers rated for 800WRMS. Don

I should have said that an amplifier with 20V/uS slew rate can reproduce any musical transient without distortion. Came from PWK in an old Dope From Hope. If you feed a square wave into a loudspeaker you won't get anything resembling a square output, unless you use mic positioning tricks. I saw that 2 weekends ago when a friend SMAARTed an installed system that he was aligning. Output @ 200 HZ resembled a clipped triangle wave drawn by a 5 year old. Amp output(QSC) had rounded corners, looked reasonably square. Don

The transient attacks in music are slower than 20V/usec, the "fastest" speakers are also. Don