minn_male42 Posted August 7, 2003 Share Posted August 7, 2003 I work at an electronics distributor for pro/commercial audio.... one of the few perks is the ability to take equipment home and "field test" it overnight or for the weekend..... tonight it is a Goldline Real Time Analyzer - Model DSP30 - over $2000 retail.... it really has too many features to list here but the most important is the 30 band analyzer of sound... it includes a calibrated mic and resolution down to .25db....(1/4 of a decibel) you can check it out at www.gold-line.com really pretty amazing...(it better be for $2000).... now to the point.... i recently aquired a dynaco sca-35 tube amp from ebay to replace a carver tfm-25 in my main system.... sharing this info at work...i got the responses...."tubes color the sound"... "tubes are o.k, but not accurate".... and so on.... o.k...let science help us..... on a test cd of pink noise for each channel and both channels combined.... the dynaco tube amp was down 4db at 16 khz and about 6db at 20 khz.... (now the best part) ... the carver results were almost identical.... the rest of the spectrum was almost flat.... (for the record... the dynaco is 17.5 watts per channel and the carver is 225 watts per channel) the speakers are Klipsch KLF-30's mated with a Velodyne CT-150 sub set at 40 hz and about half volume.... RESULTS: both amps produced almost the same result on a piece of expensive test equipment yet they SOUND RADICALLY DIFFERENT!!!!! ... my 5 year old daughter can hear a difference in the sound between the two amplifiers..... frequency response measures pitch.... but I am not aware of any device available that can measure TONE..... yet we can all hear differences in tone..... TONE is why we hear differences in most amps and speakers....yet no one talks about it.... as a musician, tone is a top priority...yet it is not discussed when talking about audio components.......??????? i'm probably preaching to the choir here...but i wanted to share my "scientific experiment" with this forum.... Quote Link to comment Share on other sites More sharing options...
JasN00b Posted August 8, 2003 Share Posted August 8, 2003 most likely the reason you hear a large difference is the 2nd order harmonic distortion tubes tend to throw in when pushed hard. thats why we guitarests love our tube amps to death, they are a) loooouddddddddd sound very natural and organic, 2nd order distortion, etc. SS amps for guitar have a very sterile clean tone, although technically more accurate. c) they glow... *stares at amp* mmmmmglowing Quote Link to comment Share on other sites More sharing options...
djk Posted August 8, 2003 Share Posted August 8, 2003 "most likely the reason you hear a large difference is the 2nd order harmonic distortion tubes tend to throw in when pushed hard." Buzzzz. Wrong answer. The 2nd harmonic 'urban tube legend' is true only for triodes running single ended in class A with no feedback. While the preamp portion is a pair of triodes running single ended in class A, there is feedback. The power amp in question is push-pull with a pair of 6BQ5 tetrode. Both those features reduce 2nd harmonic distortion. The voltage gain in the PA is from a pentode. Quote Link to comment Share on other sites More sharing options...
ben. Posted August 8, 2003 Share Posted August 8, 2003 Like PWK said, there's more to music than frequency response. (Or something to that effect). Quote Link to comment Share on other sites More sharing options...
kenratboy Posted August 8, 2003 Share Posted August 8, 2003 Your daughter, "Yeah dad, whatever, you say they should sound different, ummm, yeah, they do, which one should sound better, yeah, that one." JUST KIDDING I would still like to have a RTA that I could hook up to my computer. I figure a good $100 mic would probably fufill the duty. Quote Link to comment Share on other sites More sharing options...
ben. Posted August 8, 2003 Share Posted August 8, 2003 ---------------- On 8/8/2003 1:25:14 PM kenratboy wrote: I figure a good $100 mic would probably fufill the duty. ---------------- No such thing!! Quote Link to comment Share on other sites More sharing options...
formica Posted August 8, 2003 Share Posted August 8, 2003 Ok, I admit I'm not a musician... but just enjoy it. I'm not arguing that the $$ instrument was unable to detect the sonic difference of you two amplifiers... but I'm a little puzzled by what the true definition of "Tone" is to a musician... as it obviously isn't the scientific one? This is what I understand (from a science dictionary): FREQUENCY. The number of times per second that the sine wave of sound repeats itself, or that the sine wave of a vibrating object repeats itself. PITCH. The attribute of "auditory sensation" that orders sounds on a scale extending from low to high. Pitch depends primarily upon the frequency of the sound stimulus, but it also depends upon the sound pressure and wave form of the stimulus. And then the definition of Tone is the following: TONE. A sound of definite pitch. A pure tone has a sinusoidal wave form. Or basically pitch varies with frequency, volume (ie ±db), and wave shape (ie: sine versus a square "notch" wave). Isn't a tone is just a single pitch sound? Perhaps the sound difference we are hearing is related to the non-idealistic recorded wave shape, where a tube amp will round-over the corners of a squarish wave. I'm sure this would be much easier to see by reading it's electrical output signal on an oscilloscope, than in-room on a RTA. Just not sure on what a Tone is I guess... Rob PS: You actually mention that the response was pretty flat below 16khz... so I'm guessing at 2000$ the RTA compares it's mic input versus a direct output from signal generator to isolate the room effects... but how does it isolate the amp effects? Or does it have a direct high-level input? Most cheaper RTAs simply group the amp with the speaker effects... but having an option to isolate the different components can be fun... Quote Link to comment Share on other sites More sharing options...
JasN00b Posted August 8, 2003 Share Posted August 8, 2003 if you push tubes, they distort regardless of how they're wired... Quote Link to comment Share on other sites More sharing options...
skonopa Posted August 8, 2003 Share Posted August 8, 2003 ---------------- On 8/7/2003 8:25:13 PM minn_male42 wrote: frequency response measures pitch.... but I am not aware of any device available that can measure TONE..... yet we can all hear differences in tone..... TONE is why we hear differences in most amps and speakers....yet no one talks about it.... as a musician, tone is a top priority...yet it is not discussed when talking about audio components.......??????? ---------------- I think Formica hit it in his posting. I would believe that the only way to measure "tone" would be to actually see the wave form on an oscilloscope, given the same test-tones. There are two kinds of "Tones" in audio: The "scientific" tone is what Formica described in his post - a sound of a specific pitch - as in "1Khz Test Tone". Then there is the "musical" tone, that is the distinque characteristic of a given intrument, vocalists, etc. For example, if somebody played the "Middle-C" note on a piano and the same note on say a Harp, yes, they would be the same pitch, but you would be able to tell the difference between the two sounds due to thier "Tone". To use visual arts (which I am way more familier with), such as painting, as an anolgy. The "Pitch" would be like the "color", but "Tone" would be like the "texture". That is you could tell the difference if a shape in a piece of art was painted on or is a piece of paper glued on. They both may be the same color, but the texture would be different. Just like if a note was played on two different instruments - they may both be the same pitch, but the tones would be different. The more intersting pieces of art are often made up with various colors and textures, just like the more interesting pieces of music are made up of various pitches and tones. They are all put together in a way that is pleasing to the eye (for visual art), or to the ear (for music). Now that doesn't mean thet there must be a lot of texture and color in a piece art or alot of different pitches and tones in music - to much can make a work to busy and overwhelming for the audiance to comprehend. I have seen and heard a lot of art and music that is very beautiful in its simplicity, such as monochromatic paintings or sculptures (such as that beautiful piece in the front-lobby there at Klipsch in Indy) and simple "guitar and voice" musical pieces. Now, the only way to accuratly measure the different tones would, as was mentioned, is probably look at the waveforms on an oscilloscope. Play a 1khz test-tone through both amps and look at the resulting waveforms. Did the tubes "round-off" the corners of the wave? Are there differences in the two wave forms?. The would explain the difference in the tonality of the two amps. And all this coming from a friggan software engineer?!? Quote Link to comment Share on other sites More sharing options...
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