I like that The A/B CD has numerous comparisons of every link in the recording chain. It really puts things in perspective by showing the big picture along with the details. What kind of sound playback system should I use when listening to it?
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To best understand the impact various recording components have on recorded sound, it is suggested that you listen to The A/B CD on a number of different systems. Some of the A/B differences can be discerned only under the best of circumstances, while others can be easily heard on the cheapest of systems. For example, some car sound systems have better sub-bass response than most nearfield monitors. In such a situation, you would hear the low end differences between the analog and digital recorders better on the cars sound system. You should also listen to The A/B CD on your home system, the one you use most when listening to your favorite commercially released CDs because that's the one you can relate to best. Last but not least, you should also take the time to do a critical listening of the complete CD using some good headphones. Using good headphones in a quiet environment will allow you to notice differences not readily apparent when listening using speaker systems (like the analog tape adjacent track crosstalk, audible on Track 3 at 0:33 seconds). The following tests will determine if the system you're listening to meets listening playback requirements for a critical listening.
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Sub Bass System Test Listen to Track 3, Soundbites 0:06 & 0:17. There is a single “808” bass drum hit near the end of the musical phrase. On sound bite A it occurs at 15 seconds on the counter. On sound bite B it occurs at 26 seconds on the counter. You should notice that the 808 at 0:15 generates more sub bass boom than the one that occurs at 0:26 on the counter
Hi Frequency System Test Listen to Track 47, Soundbites 0:00 & 0:08 -You should notice more high frequencies after the counter reads 0:08.
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Signal to noise ratio test Listen to Track 10 at an average listening level. When the track gets goes from sound bite 2:45 to sound bite 2:51 you should notice a definite decrease in hiss and noise. Note: The room you listen to these two sound bites in needs to have a low level of ambient noise - even a noisy computer system can mask the difference presented by these two sound bites.
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Is that a misprint on Track 27? Its hard to believe that a home studio can sound so much better than a commercial studio.
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Considering how the final sound qualities of these two studios go against the theories and beliefs regarding the cause of certain sound qualities, It's understandable that this question was raised. To answer your question, no that is not a misprint. The basement ADAT studio has all the depth and dimension normally associated with a commercial studio, while the Trident-24 track analog-16 foot ceiling commercial studio has the small, collapsed sound normally associated with a home studio,
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How is The A/B CD different from other comparison CDs and similar attempts to show comparisons of audio gear?
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While all of them have the same purpose - to show the sonic differences between different designs of audio equipment to help people get the recorded sound they're going for, The A/B CD was engineered using methods and a format that is understandably more reliable. Here's a comparison table showing a difference in engineering methods:
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The A/B CD Method of Comparison
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Popular Method of Comparison
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A number of companies have attempted to show the sonic differences between equipment designs. Although their intentions are in the right place, the methods they have chosen are not accurate enough and therefore can lead to further confusion as to the cause of particular sound qualities. One example of an inaccurate method to compare the sound qualities of similar pieces of equipment (like mic preamps for example) is the use of different performances to compare one piece of gear to another.
The problem with this method is that frequency and envelope differences between multiple takes will disrupt any potential similarities or equalize (or magnify) potential differences. Among others, a well known online equipment retailer has chosen this "multiple performance" method of comparing equipment to present the sonic differences between mics to their customers.
One of these companies reports that the equipment levels were matched to within .1 dB using a speaker and calibration tone before each performance. Unfortunately, this confuses the situation even more because it implies an accuracy in the information presented that is not possible due to human performance tonal inflections and envelope differences greater than 3db. The online equipment retailer reports that the "average" levels of each file were matched. Average levels are important too, but this does not solve the frequency and attack envelope differences that are inherent in different performances.
See figure A.
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For the mic preamp comparisons, The A/B CD used matched pairs of dynamic and condenser mics to "split" a single performance through 2 different preamps. One of the preamps, a Mackie VLZ, was chosen as the benchmark because of it's wide spread availability in the audio market place and the subsequent way many user-engineers can relate to it.
On The A/B CD, the listener hears a full 24 track rock mix as recorded through the discrete circuitry of the Mackie VLZ mic preamps, that soundbite is immediately followed by the exact same multitrack performance as recorded through Jensen transformer coupled mic preamps.
The same 24 track song was then re-performed to compare the reference point preamp (Mackie 8 bus VLZ solid state) to a popular tube (12 AX7) preamp. By hearing the exact same multitrack performance (that starts and ends on the same pitch) through the tubes after the Mackie discrete circuitry ensures that the listener hears only the differences imparted by the equipment compared, uninfluenced by fluctuations in the human performance. Tracks 52 and 53 on The A/B CD show the validity of this comparison method by comparing pairs of two identical preamps to each other.
The A/B CD format of using matched pairs of mics along with benchmarking is the most accurate and relatable way to impart the sonic differences or similarities in recording equipment such as mics and preamps.
See figure B.
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Figure A. These two 3D graphs were made from mic comparison MP3 files created by an online equipment retailer. The professional sounding female vocalist sang into one of the mics then, after a while, sang the same vocal line into the other mic. The problem with this "multiple performance" method of equipment comparison is that uncontrollable differences from one performance to the next makes it impossible to show the true similarities the gear might share and potential differences are at times compromised, at other times magnified. The listener ends up hearing comparisons of different vocal takes more than hearing comparisons of different equipment.
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Figure B. For The A/B CD mic comparisons, a Shure dynamic mic was used as the benchmark (reference) mic because they are readily available and its a mic people are familiar with. On Track 14, a Neumann U87 condenser mic is compared to a Shure SM58 dynamic mic. The U87and SM58 were placed as closely together as possible, both capsules were in the same plane and both mics used the same cabling and preamps. The female singer was about 8 inches away and sang the vocal line ONCE into both mics which were recorded onto separate tracks of a digital recorder*. Unlike comparisons made with multiple performances, the peak to average level ratios are inherently the same for both pieces of equipment being compared using this format. With The A/B CD, the listener hears a piece of equipment they can relate to (the benchmark), a Shure SM58 mic in this example, then they hear the exact same performance through the piece of gear they are not familiar with - the Neumann U87 mic in this example. With The A/B CD, the listener hears a comparison of the equipment in question not an inadvertent comparison of different performances. Track 15 repeats the process with a Shure SM57dynamic mic as the benchmark, compared to an AKG 414 condenser mic, using a single take sung by a male vocalist as the sound source. *Different formats of digital recorders are also compared on The A/B CD.
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