Real Time Analyzers - Pitch vs. Tone

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....

 

Isn't it the truth though Russ.

 

Are you sure those measurements aren't your speakers and not the amplifiers?

 

you're right..... i am measuring the speakers as well as the amplifiers....

my point was about comparing two different types of amplifiers!

 

Yes, but primarily as it applies to the frequency of sound waves produced by a source. As mentioned, what you're measuring now is mostly the speakers' interaction with your room, not the amplifiers' interaction with the speaker.

I think a more accurate test would be a full 'scoping of each amplifier at its output; you would then likely see some significant deviations in frequency response (dips/peaks) across the spectrum, which might better correlate to differences in an amplifier's sound, or what you've termed "tonal" differences.

That is not my experience at all. I see references to "tone" all the time in discussions and reviews. Some of this difference is postulated to be the result of differences in measured frequency response, some to amplifier/speaker interaction (impedence, efficiency, power), some due to the inherent sound of different components (capacitors, resistors, etc.). I don't think you're preaching to the choir here, because there are members here who would disagree that that last statement has any basis in fact .

To sum up: From the standpoint of a "scientific experiment", you certainly have learned something about how your speakers and room interact to affect frequency response, but IMO I wouldn't go so far as to say you're able to make any accurate conclusions about the amplifiers from this type of acoustic (vs. electrical) measurement.

John K.

 

What sort of impulse response do you get with those speakers hooked up to those amps? I'd bet you'd see quite a difference between the two.

 

"That is not my experience at all. I see references to "tone" all the time in discussions and reviews. Some of this difference is postulated to be the result of differences in measured frequency response, some to amplifier/speaker interaction (impedence, efficiency, power), some due to the inherent sound of different components (capacitors, resistors, etc.). I don't think you're preaching to the choir here, because there are members here who would disagree that that last statement has any basis in fact"


"TONE" as a musician is very different than what is discussed online and in reviews....

for about 10 years i was a music judge for the state of minnesota in the minnesota state high school league music contests...."tone" was a one of the ten categories that each contestant/group was judged in.... a musician could have perfect pitch and have reproduced all of the notes accurately according to the score...... yet if their tone was lacking or substandard, they might not achieve the highest rating...

i know that this is not the usual direction these audio forums run... but we are talking about music reproduction.... and in actual music performance, tone is a great priority....

if you can measure all of the overtones and the sound of a performer on a "scope that is great.... but what measurements sound good?????

what degree of certain overtones indicate "good sound"?....

it all comes down to what the ear prefers... for me, my tube amp sounds better than my solid state amp (in my room with my speakers)..... and from what i read in many forums, i am not alone......

i know my limited scientific "experiment" has its problems but the fact that "tone" in its true musical sense is really the only thing that i can see (or hear) as a difference between my two amplifiers in my setup and room IS VALID!

 

Yes, but that didn't seem to be the original point of your post. I, too, find tube preamps and amps more faithful in terms of musical tone, but, what you described was, in my opinion, not a "scientific experiment". It was, indeed, an observation of differences, but IMO it did not attempt to determine the cause of the differences in a scientific way.

Let me say that this is not a simple topic. One example is amplifiers of the '70s, where they measured with distortion figures of .001% or less, but were, essentially, unlistenable. Current SET amps may have distortion figures of 3% or more, but are often preferred by listeners.

John K.

 

John,

thanks for your observations.....

i am more of a musician than a scientist.....

you are totally right..... lots of problems with my scientific method.....

i guess hearing about tube amps "poor frequency response" and "rolled off high end" from some of my co-workers prompted me to do my "experiment!!

thanks again for your feedback..