John Curl's Blowtorch preamplifier part II

[scott wurcer]

Originally Posted by john curl

The MD isn't stupid, usually well educated, yet not really technical, and this seems to help to avoid prejudice against what is sonically possible and what is not.
.

I've had several millionaire friends with Bose 901's and old Macintosh amps and they were in heaven. As W. C. Fields said never smarten up a chump.

[Soundminded]

Originally Posted by john curl

Any SERIOUS listener can hear the difference between vinyl and digital. If you can't, then I would recommend another hobby. If you persist in audio for some reason, it would be appreciated if you would let the rest of us alone, to enjoy audio reproduction using our own expertise and experience to help others do so as well.

If this were your blog, you could arbitrarily censor people whose views are diametrically opposed to your own. You could be Tsar of your realm. But that is not the case. My experience is entirely different from yours and you have no way to know whether it is or isn't any more valid than yours is.

One difference in our experience, I never exposed my ears to 130 db unprotected even unwillingly and I do not like the kind of sound produced by groups like the Grateful Dead, never did, never will. In that regard, it seems with time, age, and experience, your views have come closer to mine than the other way around. As you have not produced the perfect sound system yet, you should be at least tolerant if not open to views other than your own. You may not agree with them, you may not even understand them, but until proven wrong, they have as much chance of being right as yours do.

[Soundminded]

Originally Posted by scott wurcer

I've had several millionaire friends with Bose 901's and old Macintosh amps and they were in heaven. As W. C. Fields said never smarten up a chump.

I tried on two occasions to re-engineer original Bose 901. The fist effort sometime in the 80s and 90s ended in complete failure. The second about ten years later after much experience with re-engineering other models was highly successful. By that time I knew exactly what was wrong with it and how to fix it. Even so, it took almost four years. I don't expect anyone to believe it without having heard the results. The shortcomings of this speaker system as manufactured are obvious and unacceptable to those who are looking for an accurate reproducer of acoustic musical instruments and voices. However, its novel direct/reflecting principle has substantial advantages over direct firing speaker systems when correctly executed. It also has other advantages.

Even after re-engineering, it cannot reproduce the acoustics of a large hall or any other hall for that matter. What it can do when carefully adjusted for each recording is to accurately reproduce the sound of musical instruments as they would be heard if they were in the same room with you. This restricts its usefulness to soloists and small groups. Its main shortcomings IMO are 1) it cannot reproduce the highest octave of sound, 2) it has a substantial peak in the upper bass/lower midrange, and 3) its deep bass falls off too fast starting at around 200 hz. It falls at 6db per octave and reaches the 1khz level at around 90 hz below which it keeps falling. This requires additional bass boost increasing its power requirements to reproduce the lowest octaves substantially. Therefore it eats up power like a sponge. It may be the least efficient speaker at low frequenies I've encountered. Without multiple pairs and lots of amplifier power its deep bass output is therefore somewhat limited even in a small room. However, within its power handling capabilities, it will compete against much larger speakers like Teledyne AR9.

Starting with Series III, the design changed from acoustic suspension to ported. I haven't had any experience with any of the newer models but I expect that efficiency increased at the sacrifice of the lowest octave. Listening to Series VI in a mall in Newport Beach Ca about 3 years ago, it seemed to me to have the same dull inadequate high end the originals have.

[soundmeister]

"No Highs, no Lows...that's Bose" - standard saying in the pro sound reinforcement world.

[soundmeister]

Originally Posted by john curl

In those early days, analog tape was really the best mode of sound recording and reproduction, with magnetic film recording a close second.

Were there other viable methods ?.

Even phono, with the relatively lousy phono cartridges, tone arms and turntables of the time, tended to make magnetic tape MASTERS superior in almost every way. Still, I found that I could NOT record a 15ips/1/2 track master tape that sounded as GOOD as a quality vinyl record, and THEN they started to make DIRECT DISC RECORDS. These were actually better than a master tape, in most ways.

Do you mean a tape copy of a vinyl record not sounding as good as the original vinyl ?.

Digital was nasty in 1968, and it only got slightly better over the next decade. We tried everything, more bits, higher sample rate, analog shift registers (for delay lines), consulted PhD's to make the highest quality anti-aliasing filters, yet we always got less than perfect reproduction from digital.
This did NOT stop Sony, and many others, who seemed to be immune to digital artifacts, from decrying 'Perfect sound forever!' for the last 30 years.
Even still, we TRIED to 'fix' the problems by making better oscillators, lowering jitter, increasing bits, raising sampling rate, yet we still can hear the artifacts, even if they are now at an almost unconscious level.

Maybe one day the standard transport medium will be uber high-res digital...and that ought to be better than analogue tape or vinyl.

Any SERIOUS listener can hear the difference between vinyl and digital. If you can't, then I would recommend another hobby. If you persist in audio for some reason, it would be appreciated if you would let the rest of us alone, to enjoy audio reproduction using our own expertise and experience to help others do so as well.

Hearing a two track master and immediately hearing the 44k/16bit version is like chalk and cheese - the life in the performance is deleted in the digital version.

Dave.

[john curl]

Well Dave, at least you can hear the difference. Yes, what I meant to convey was that I purchased an Ampex pro tape record recorder back in 1967, in order to record my favorite vinyl records and put them on tape, in order to save the extra wear on the vinyl, itself.

The REAL DIGITAL challenge, is: WHERE DID THE LIFE OF THE PERFORMANCE GO?
Some say: 'It is just our imagination' others say: 'You are just prejudiced about digital', yet others say, that many of us miss the distortions often audible in a poorly engineered analog recording and playback.
I, personally, would like digital to be as good or even BETTER than analog.
Now, I don't have a lot of investment in digital, myself, but many of my customers do.
I have been invited to listen to a 1/2 million dollar system, on occasion, and I want to leave the room, after 1/2 hour, if the presentation is digital. If vacuum tube amps are used, maybe 1 hour would be possible. Still, vinyl rules, and the was shown at the latest CES in several of the best demonstrations. Why? Because it conveys the 'EMOTION' of the performance, not just the information about the performance. Go figure. If we solve this, then we will have solved the digital-analog dilemma.

[PMA]

Might be that pure technical means are unable to re-create original sound field, thus emotion transfer is impossible. That's my view.

[Steve Eddy]

Originally Posted by john curl

The REAL DIGITAL challenge, is: WHERE DID THE LIFE OF THE PERFORMANCE GO?

Perhaps it went away along with the distortions of the vinyl medium?

se

[Soundminded]

Originally Posted by Steve Eddy

Perhaps it went away along with the distortions of the vinyl medium?

se

There are many reasons why a vinyl phonograph record may be more pleasing to listen to than an equivalent cd that have nothing to do with limitations of the Redbook CD system. Among them;

Between the time the vinyl and cd were issued, the master tape may have deteriorated.

The dynamic compression of recordings edited for vinyl records can have desirable effects by making the last part of each musical phrase and the recorded reverberation louder.

The skill in mastering the vinyl version may have been greater than the skill used in mastering the cd version.

Choices of equalization in the vinyl era were made using speakers that were equalized for flat response, their calibration often checked weekly by the larger recording companies creating greater uniformity of the spectral balance from recording to recording, record company to record company although there were variations. Many recording companies used the same speakers for monitoring, Altec VOTA A7-500. In the CD era not only do companies use different speakers, the idea of equalizing speakers is out of favor and spectral balance even on the same label is all over the map. In one instance, even recordings of the same group played by the same musicians in the same studio but recorded by different engineers and issued on two sequential catalog numbers from the same company are substantially different.

A comparison between the cd version and vinyl version of Carol Rosenberger playing Water Music on a Grand Bosendorfer piano on the Delos label sounded identical to me. The vinyl was played on an Empire 698 with a Shure V15 type V MR and the cd was played on a Toshiba DVD player circa 2007 with a 192khz 24bit processor. That CD player sounded identical on factory made duplicate cds with a JVC 1 bit 8x oversampling player circa 1991. Even their output level was indistinguishable. Conclusion, both players perform their function flawlessly. They are good enough for any audio recording. If there's a problem, it's elsewhere.

[john curl]

Well, lots of opinions and very little 'proof'. My 'proof' is in my experience making recordings, hearing digital 'equivalents', using direct disc vinyl as a good reference, for fidelity, and the experience of my colleagues ACTUALLY WORKING in the audio industry, rather than 'arm chair' critics who dabble in audio design, and in truth, confuse me with the contradictory conclusions that they come up with.