این مطلب هفتصدمین مطلب این وبلاگ هست.

فکر میکنم بد نباشه دو کار انجام بدم ، یکی نقد همه چیزهایی است که از گذشته نوشتم و دیگری حفظ کردن لینک هایی که به بیرون دادم و ممکنه اون لینک ها تا مثلا 20 سال دیگه کار نکنند.

شاید بهتر باشه بیشتر لینک ها رو مطالبشون رو پی دی اف کنم و از تو سایت خودم دانلود بشن تا مثلا 10 سال دیگه اطلاعاتی بیرون سایت نباشه که نشه بهش دسترسی داشت.

سه خبر هم دارم غیر های فای :

یک دوستمون از بالای پل پردیس با ماشین افتاد پایین و 8 تا ایربگ باز شد اما چیزیش نشد خدارو شکر ، 11 متر سقوط آزاد.

یک دوست دیگرمون تو آسانسور بود که با سقوط آسانسور بدجوری صدمه دید و رفت زیر عمل ، خدارو شکر فقط شکستگی بود که حل میشه.

یک دوست دیگرمون هم تو لبنان رفت داماد یک خانواده بشه که بدلیل تفاوت مذهب ریختند سرش آلتش رو کندند.

خب برگردیم به های فای

مطلب زیر اولین مطلبی هست که من تو این وبلاگ نوشتم اونم در تاریخ 19 شهریور  1385  :

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موضوعی که قبلا هم مطرح شد بحث مچینگ بین بلندگو و آمپلی فایر هست. بنظر آرتور سالواتوره این مچینگ بسیار بسیار مهم هست ، خیلی بیشتر از تصور عموم آئودیوفیل ها و یادمه تو سایت آئودیو پکس Audio PAX قبلا مقاله ای بود در این مورد تو سایتم بهش اشاره ای کردم و دلیما میگفت مچینگ بلندگو با آمپ خیلی مهم هست و حتی مثالی آورد از اینکه اگر بلندگو دیستورشن اش هارمونیک دوم با فاز x باشه و آمپ هارمونیک دومش با فاز x صدو هشتاد درجه اختلاف داشته باشه این دو همدیگر رو تا حدی خنثی میکنند.

میدونیم فیدبک هم تو بعضی آمپ های لامپی مثل Lamm از بیرون قابل کنترل هست تا دمپینگ فکتور بر اساس بلندگو تغییر کنه و حتی نسبت ترانس خروجی لامپ ها هم تو مچینگ موثره و برای همینه ممکنه تو تنظیم 8 اهم صدا با تنظیم 4 اهم فرق کنه.

پس جای تعجب نداره اگر ما تجربیات متفاوتی از یک بلندگو یا یک امپ در مچینگ های مختلف داشته باشیم همونجور که تو اتاق های متفاوت بلندگو صدای متفاوت داره.

در ادامه این بحث به طراحی برخوردم که مطلبی در این مورد نوشته بخونید :

http://www.6moons.com/audioreviews/tomevans/lineara_4.html

Tom Evans Audio Design

The Amplifier/Speaker Interface
Tom believes that today’s HiFi design culture has been looking at things “the wrong way ’round. First, HiFi requires a source such as vinyl, CD, radio or tape. Then we need a whole heap of voltage & current gain to drive a loudspeaker or two. After the signal leaves the source, the major factor determining a HiFi’s ultimate sound quality is the amplifier & speaker combination being used. Some might say, ‘Aha! But don’t all amplifiers sound the same? It’s the speaker that sounds different. You know: The boom & tizz, the sibilance & bass, man!’…”

Tom stresses that it’s the interaction between amplifier & speaker that determines the sound as a whole. You have to engineer with that in mind to extend the edge of the art in amplifier design. “There are more permutations of amplifier & speaker combinations than you can count. To get an optimum match between most amplifiers and speakers, you have less chance of success than winning the lottery. One of our design goals had to be that the Linear A would work equally well in all those interaction situations to ensure consistently good sound for all of our customers. Keep in mind that the laws of physics will apply to anything electrical and mechanical. We’re faced with designing for an infinite variable of customers with different room sizes, aesthetic tastes, budget, differing equipment and the often-overlooked fact of the frailty of human hearing slowly fading from constant use. The end result is that the same system in different rooms and with different ears will sound different for better or worse.”

Tom uses the following analogy to illuminate loudspeaker/amplifier interactions: “The problem that most speakers pose for an amplifier is that from an electrical standpoint, they are moving targets with respect to impedance versus frequency. Imagine you’re sitting at a piano. The furthest key to your left plays a 27Hz note, the furthest key to your right a 7000Hz note. Loudspeakers try to mimic the sound of those two notes from a recording yet each note presents a different electrical load to the amplifier due to the way loudspeakers are constructed. In the same way, a 40-watt light bulb presents a different load to the mains than would a 100-watt bulb. Just as one light bulb emits more light, one note is easier to drive from an amplifier’s point of view.”

“It’s a widely held belief in the audio community that a high damping factor is all that’s required to drive any speaker impedance curve. Actually, the truth is that the damping factor merely stops the speaker from ringing or bouncing like a spring once the music stops. As has been shown by Gilbert Briggs, founder of Wharfedale, the amplifier output impedance only needs to be half the speaker’s impedance to have this effect. I can hear you laughing and thinking we’ve lost our marbles – but how come all amplifier manufacturers quote different power outputs into 4/8/16 ohms when the magic low output impedance means it allegedly produces the same power irrespective of load? Worse even, transformer-coupled tube amplifiers use multiple impedance taps. Look at any loudspeaker. Very few are ruler flat over their frequency range and most look like the side view of a roller coaster fairground ride. A 32-ohm peak at bass resonance and crossover point requires double the voltage of an 8-ohm load as does a 16-ohm peak against a nominal 4-ohm load. Remember that amplifiers clip when supplying higher voltages and that all amplifiers have a falling power output into rising impedance. As a result, the driver has a frequency response rolloff as the impedance rises.

The rising impedance with frequency, as seen by the amplifier, produces a benign inductive load. However, the corresponding fall with frequency is capacitive and will cause the amplifier output devices to overheat. Because the Linear A uses an output transformer and operates in Class A, it is immune to any of those ills usually associated with amplifiers. Since the valves don’t see the loudspeaker (only the transformer), and because they are on all the time, they don’t draw more current at higher power. However, the major advantage of the Linear A is that we have matched the transformer and composite valve to produce over 20 watts between 5-10 ohms. The speaker output remains the same when its impedance curve fluctuates anywhere between 5 and 10 ohms. The fall in power above 10 ohms is offset by the improved output transformer efficiency. Since transformer losses are “current squared x winding resistance”, the current requirement falls off with rising impedance. In sonic terms, it means your loudspeaker presents a less peaky sound output if you are using a Linear A.”

این شخص شرکتی داره بنام Auditorium 23 که تو اروپا فعالیت میکنه و برای جلب توجه مخاطبان سیستم هایی رو دمو میکنه که بتونه علاقه اونها رو به سمت هورن ها و سینگل اندد ها و سورس آنلوگ جلب کنه.

لینک زیر گزارش حاج جف از این آدم هست :

http://www.6moons.com/audioreviews/auditorium23/23.html

Keith Aschenbrenner of Auditorium 23
Auditorium 23 is a HiFi import-export, retail sales and research & development business in Germany. It was established in 1980 and is owned and operated by Keith Aschenbrenner. Keith is largely unknown in the USA HiFi scene, except among those in the audio underground who are knowledgeable about the early history of the SET movement in France and Germany; or those hip to the glories of single-ended triode amplifiers, Platine Verdier turntables or the magnificent & historic Siemens Klangfilm loudspeakers (which have made a few select appearances at US HiFi shows in the last couple of years). At home, Keith has achieved the status of cultural audio icon over the years. His admirers refer to him as the Tube Apostle of Germany for his trials, tribulations and ultimate success in introducing fellow German HiFi and music lovers to the glories of the combination of vinyl playback, singled-ended-triode (SET) amplification and high- sensitivity loudspeakers, all built using the best principles of classic designs. I get the impression that Keith is a little uncomfortable with the domestic notoriety bestowed upon him, preferring instead to modestly play it down by viewing himself first and foremost as an audio everyman and music lover – just like you and me.

L´Audiophile (http://www.audiophile.lu/)
In the early 1980s while traveling to Brittany in the west of France during the holidays, Keith came across the French enthusiast audio magazines, most notably the well-known L´Audiophile. L´Audiophile had opened a shop in Paris to demonstrate their do-it-yourself (DIY) projects and to sell parts to the DIY- infected HiFi hobbyists of France. Listening to music at L´Audiophile over their system was a shock to Keith. He immediately realized that his HiFi system at home was a far cry from the musical realism and dynamic truths that L´Audiophile achieved so easily in their demonstrations of Altec/Onken & Voice of the Theatre systems powered by a 20-watt Hiraga amplifier & Kaneda preamplifier, with a Platine Verdier turntable spinning the tunes.

When Keith went back home to Germany and listened to his system, he “realized it was just a ping-pong music experience. It was not bad really but the main fault was that I had been focusing on soundstage as a general target. I was looking between instruments instead of listening to music. It was more of an audio-visual experience than the row twenty musical experience of a concert hall. After being touched by the experience at Maison L´Audiophile, there was no way for me to go back.” Keith sold his gear and purchased a 20-watt Hiraga Le Tube, Kaneda DC1 [upper left], a 12-inch SME 3012 tonearm and a Denon 103 cartridge.

Keith admitted that after hearing the Shindo products, he thought that if he wanted to make a meaningful contribution, he would have to focus on loudspeakers instead of amplifiers. The market for loudspeakers was very different between Japan and Europe. It became his goal to find solutions in the European market that were “helpers for the little green amplifiers” from Japan. For example, the little Shindo Claret preamp had only two MM inputs. Given that the Denon 103 was Keith’s favorite inexpensive phono cartridge (and a moving coil), he tried experimenting with a couple of different transformers from a German transformer producer. When Keith found a transformer he really liked, he sent samples to Ken Shindo to get his opinion. However, Ken Shindo speaks no foreign languages. His answer to Keith was to send the next Claret preamplifiers with holes in the panels so Keith’s customers could add the transformers they wished – a non-verbal answer to a non-verbal question.

Keith pondered how Ken Shindo’s amplification products could be so successful at interpreting reproduced music when other approaches struggled so much with it. Ken Shindo’s design principles harkened back to an earlier era in audio. Keith believed those early principles were Ken’s — and now his — key to musical realism for any personal future loudspeaker designs. Keith began to research examples of those early designs to see if he could find out what made them work so well. Keith also investigated classic cartridges & tonearms and EMT broadcast turntables. He investigated legendary loudspeakers like Klangfilms, Altec woofers & drivers in custom Onkens cabinets and Voice of the Theater loudspeakers. Keith researched how the Western Electric philosophy differed from the Klangfilm philosophy and how the Westrex London philosophy compared to that of Vitavox or Cinemeccanica of Italy. With those loudspeaker designs for example, Keith realized that the quality of the wood construction had a lot to do with the quality of the sound. This discovery prompted him to contact the American Plywood Association. He wanted to learn more about the different grades of wood available and which ones would be best for creating cabinets in the Golden-Era manner. Keith found out that the best grades of plywood were not exported to Germany. This initially made things a little more difficult but they found a solution. Keith demurred. “This is only one example of the many challenges we encountered as we refined our understanding of how to get the full musical realism that those early high fidelity designs of Wente & Thuras, Harrison and Maxfield were capable of.”

They researched ideas as diverse as the operation of gramophones and electrical recording, electrical reproduction, the importance of tone to achieving an emotional response in film sound and the like. At this time, Keith realized how important tone was in evoking the full emotional response in cinema. Keith reminisced. “People voted with their feet by going to those cinemas where tone quality touched their souls.” The sound systems for the cinemas of those early days were not mass-produced products. Only a few operators were able to afford a Lansing Iconic system in the 1940s. The prices for oil capacitors in the 1950s, for example, were very expensive compared to people’s average salaries.

The HiFi industry of the 1960s and 1970s then departed from the finely tuned, expensive, hand-made and musically realistic high fidelity systems of the 1940s and 1950s. It turned to mass production, employing a lot of people to make its products. “It was the beginning of a change that would lead us to the consumer audio era of today with its digital amplifiers and kids who think the speakers of their iMacs are the golden standard. What I’d like to say is this: Listen to an original Altec 803 woofer with a paper surround or a 416 8C with a ferrite magnet and tissue surround using top quality electronics like Shindo. You will immediately understand what we have won and what we have lost.”

Keith has gained many insights researching historic audio designs and the principles that allowed them to infuse the breath of life into the music. I got a momentary glimpse of what these historic designs are capable of in my all too brief encounter with the Siemens Klangfilm loudspeakers at CES a few years ago. Those huge Klangfilms produced a riveting emotional experience that left me with the realization that we have a long way to go to make up for the ground we lost in musical realism and emotive ability over the last 30 years. When will the next Klangfilm appear? Will it ever? Or perhaps it has already?

In 1997, Keith unveiled his new Provence loudspeaker. It was remarkably different from what others were doing in loudspeaker design at the same time, what with its heirloom furniture quality construction and wide & flat chassis with an open backside. The Provence was a full-range loudspeaker with the French PHY-HP driver. Jean-Marie Piel, chief editor of the French Diapason magazine and owner of a complete A23 Shindo system, had introduced Bernard Salabert of PHY to Keith. PHY and Auditorium 23 were working with the material bronze in audio applications at the same time. Upon reviewing the Provence, Piel wrote in Diapason how this new speaker was “the intelligent combination of everything that had been done right in loudspeaker design during the past 50 years”. Aschenbrenner’s other loudspeakers designs (the Latour, Marsannay and Morgane) were unique designs based on the historical principles of Altec, Siemens and Western Electric. Keith is particularly fond of Bernard Salabert’s PHY drivers and believes they compare favorably to such historic designs as the legendary WE755. In fact, Keith does not believe there is a single present-day driver that can compare with the musical qualities of the PHY-HP H21-LB15, its only competition being the best drivers of the 1940s and 1950s. Keith doesn’t fancy over-damped cabinets either: “We learned how a small speaker cabinet for a full-range driver can be built like a musical instrument in order to fully develop its musical tone. For these applications, we wondered what would happen if we used the same kind of wood musical instruments are made of.” This led to the creation of the Appassionata loudspeaker built from the same wood that piano soundboards are fashioned from. In the brochure to the Appassionata, its maker admits that this particular design approach should not be embraced as the one and only valid way.