Updated: Sep 2, 2020
Dear Get Better Sound readers,
Welcome to the first issue of Quarter Notes! As I’ve written elsewhere, Quarter Notes is a quarterly newsletter for Get Better Sound readers, expanding on the manual, as well as introducing new and timely subjects. We may have a guest writer on a special topic. We may have a series of answers to the many questions I receive. In fact, send me an e-mail and I may include your question or comments in an upcoming newsletter.
Best e-mail address Since you’re reading this, the e-mail address that I used to notify you must have worked. However, the only e-mail address I have is the one associated with your initial Get Better Sound order. If you have an e-mail address that you’d prefer to use to receive Quarter Notes notifications, send it to email@example.com. Be sure to list the month of purchase (if possible), and definitely include the address I used originally along with the one that you want to use to replace it.
Tesa tape Guess I didn’t give enough info about the tesa tape that I mentioned. A few years ago, when I bought a supply of it, you could get it in a store like Lowe's or Home Depot. I wasn’t aware they’d since changed their distribution.
Since there is no model number on the roll, I recently contacted their US product manager and sent him a sample. He said that it appeared to be tesa #4651. To get it, you have to contact tesa and they’ll give you the local rep’s contact info.
Wow! Can they make it any harder to get? That’s a lot of trouble for some tape. Anyway, tesa US can be reached at 800-426-2181. The web site: http://www.tesatape.com
In other countries, tesa can be reached at http://www.tesa.com/company/worldwide
Master the mister OK, I meant this one to be in the manual, but I just ran out of time. Actually, for many years, I didn’t think of it in the context of home systems.
I first noticed it when I was making broadcast recordings for the Public Radio affiliate locally. Sometimes, between the first night’s concert and the second night’s event, the weather would change dramatically.
Even though the concert hall was closed off and supposedly free of climate differences, the reality was that if one night the air was fairly dry and the next night it was more humid (perhaps a low-pressure weather front had moved in), there was a noticeable difference in recorded sound quality.
Now, it’s important to note that my condenser microphones were hung in the same place overnight, and had not been disturbed in any way. Recording levels were untouched for each piece. The exact same program and the exact same orchestra would be on stage in the exact same place.
When the air in the concert hall was relatively dry, the sound was always a bit on the dead side. When the hall was relatively more humid, the sound was more extended and lively.
The attenuation of sound in air is affected by the relative humidity (RH). Dry air absorbs far more acoustical energy than does moist air. This is because moist air is less dense than dry air (water vapor weighs less than air)!
The velocity of air is at a minimum at a relative humidity (RH) of about 14%; then it rises. Above about 30% RH, the velocity increases linearly with increasing moisture content.
Furthermore, it’s been documented that in concert halls, low RH results in reduced high frequency reverberation time.
So what does all that mean?
It means that you may get a more lively sound with RH at or above 25-30% in your home. Because I have very dry heat, I find that the liberal use of a mister in my listening room helps a great deal. Do I actually hear the difference? I think so, but it could be that the room is simply more comfortable. So I enjoy the system more.
Whatever the reason, I use a 24-ounce handheld mister bottle in the winter in the dry heat. I even use it in the summer occasionally. I mist the plants and some other objects in the room that will absorb the mist. I spray a fine mist into the air, being careful NOT to spray in the direction of my electronics and especially my power amplifiers.
By the way, I mentioned that I hadn’t thought of it for stereo playback. George Cardas first suggested the idea to me for playback systems at a show demo.
FWIW – I used it at two big shows – one was the Stereophile HE Show in San Francisco in the fall, and another was at CES in the dead of winter at Las Vegas. Both times we won Best Sound at Show comments by many, including in print by TAS Editor Robert Harley.
I misted the room between demos (every thirty minutes). Was the mister the secret ingredient? I don’t know. I do know we had lines of folks waiting to listen. And that we got applause at the end of the demos.
Why not try it and see for yourself?
Of course, I can’t guarantee how much applause you’ll get.
Why single-ended amplifiers can sound so good It’s not because of magic dust. Or even tube sound. In fact, a single-ended amplifier can be solid state.
It’s primarily due to the fact that a single ended amp doesn’t deconstruct the musical signal and then have to reconstruct it at the outputs. This “tearing apart” of the musical info into positive and negative waveforms is very tricky. Putting it all back together again is very tricky. So it’s exponentially tricky.
A single ended amplifier keeps the waveform intact, from input to output. As usual, simpler is often better, or at least, pretty interesting.
Why single-ended amplifiers can sound so bad Most single-ended amplifiers end up having a fairly high output impedance (especially vacuum-tube SE amps). I’m not going into the technical aspects of it here. What counts is the audible result.
Loudspeakers generally have a widely varying impedance at various frequencies. An amp with a higher output impedance will deliver varying amounts of power at varying frequencies as the impedance of the speaker at those frequencies changes. Simply said, the loudspeaker you selected for its smooth frequency response no longer is so smooth.
And if you auditioned that loudspeaker with a single-ended amp, it may still be subject to significant frequency response fluctuations if the amp is different in design than the one you heard on your speakers. The same can be said if the demo used a tube amp with one set of output taps (say, 4 ohms) and you use another, (say, 16 ohms). The overall tonal balance of the system will be shifted at various frequencies in ways that almost seem to be unpredictable.
The higher output impedance of a SE tube amplifier means that its damping factor will be lower than that of other push/pull tube amps, and considerably lower than transistor amps. Lower damping factor can generally be attributed to less bass control.
However, you may find that the directness and the intimacy of a single-ended amp outweighs the colorations of its uneven frequency response and less bass control.
I confess to having been beguiled by that sound from time-to-time when the SE amplifier was paired with an appropriate loudspeaker.