#frequency response

[audio-luddite]

Something weird this way comes.

I go down a lot of pathways that become the notorious rabbit hole of knowledge. Recently I bumped into a strange phenomenon about hearing. Ultrasonic hearing. Human ultrasonic hearing is a thing.

This is not some superpower of a human / dog crossbreed it is a thing in normal people.

Basically experimenters exposed people to frequencies far above 20khz. They could not identify the tone, but they did perceive something was there. Presence of an ultrasonic carrier appeared to enhance clarity in some experiments. In others it increased the comfortable listening level of some music.

This is not rigorously accepted but there is evidence depending on the study methods. Scientists have found something.

Apparently they already knew that with bone conduction relatively normal people can perceive 28khz. Some of these other experiments used over 40 khz and up to 120khz. Crazy right?

Where am I going with this? My hearing taps out at 12 khz last time I checked. In my not-at-all-rigorous comparison tests of streaming I think something is missing. What if this something is ultrasonic?

My preamp is rated at the line level to 200 khz. The phono is rated to 40khz. My ARC Cl60 is rated to 40khz. My phono cartridge is good to over 40 khz. My speaker tweeter will go to 40khz but response drops rapidly. If there is something on the source it can get through.

CDs and Streaming signals have filters to block signals above the Nyquist frequency of 20 to 22 khz. DACs have to filter ultrasonics hard. Ideally as I understand it nothing above those frequencies is even on the source.

Note that I and most others who prefer the sound of a good LP use that word "prefer." In these experiments subjects also prefer sounds with ultrasonic content.

Old school speakers often had "super tweeters" that work far above 20 khz. People liked them.

We know normal human limits from anatomy. The size of the tiny hairs in the cochlea and the mechanical characteristics of the hearing mechanism. It aint just beep tests into headphones.

We also know that frequencies can interfere with one another, modulate, and beat on each other. Is there some kind of modulating happening? Say two ultrasonic signals modulate each other and create an audible signal.

This has already gone deep into the math I do not feel comfortable with.

Is it possible that LPs have some ultrasonic content? I know DMM cutting modulates the cutter with I think 45khz to facilitate the cutting process. I have heard some lacquer cutting does that as well. Analog systems can record frequencies above audible. Double the tape speed of a Reel to Reel deck and arguably double the frequency response. 30ips tapes sound better you know.

The famous Sheffield Direct to Disc albums sound more clear and real. Is it because there is ultrasonic information in there? An FFT analyzer could find it. I am not that much of a geek or rich enough to have one.

It would be so cool to show that there is a reason to prefer LPs aside from just liking them.

[takmiblog]

(http://www.op316.com/tubes/balanced/balprefet-v2.htm)

デジタル時代のソースは、サンプリングレートによってオーディオ帯域が制限される、ソース機材からデジタルノイズが漏れてくる、といった特徴があります。ソースを再生するオーディオ装置は広帯域であるほど良いとも言い切れなくなってきました。またデジタルノイズの有無にかかわらず、そんなに広帯域でなくとも非常に良い���で再生できる・・・広帯域が良い音の絶対条件ではなさそうだ、ということもだんだん見えてきました。

このラインプリアンプは私がこれまで製作してきたものに比べると高域側の帯域はあまり広くありません。1990年頃に製作したプリアンプは1MHzで-3dBという超広帯域で、2006年に製作した差動ラインプリでは500kHzで-3dBでした。しかし、本機は75kHzで-3dBとなっています。その理由のひとつはデジタルソースから漏れ出てくるノイズへの対応です。この種のノイズは100kHz～2MHzくらいに広く分布しており、これが目立つと音のうるおい感が損なわれ、ざらついた感じになってきます。今や、オーディオソースの大半がデジタル機器ともいえる状況なので、ひとつ考え方を改めてプリアンプというものを再設計してみようと思ったわけです。

by　ぺるけさん

[pddparthi]

Unveiling Precision: A Guide to Electrohydraulic Servo Valve Technology

Introduction: In the realm of industrial automation and high-performance machinery, electrohydraulic servo valves (EHSVs) reign supreme. These marvels of engineering bridge the gap between electrical control signals and the potent world of hydraulics. By translating subtle electrical commands into precise hydraulic fluid motion, EHSVs empower motion control systems with unmatched accuracy and…

[musicianfiend]

Understanding In-Ear Monitors

Understanding In-Ear Monitorsby Wolfgang Allen Table of Contents: Introduction to In-Ear Monitors (IEMs) Definition and Purpose of IEMs Historical Evolution Advantages of IEMs Components of In-Ear Monitors Earpieces Cables Connectors Drivers Filters Selecting the Right In-Ear Monitors Considerations for Musicians Audiophile and Consumer IEMs Custom vs. Universal Fit Sound…

[truly-sincerely]

ALEX RIDER (BOOK 1-5) TIMELINE

According to years given in Skeleton Key the books all take place in 2001. Alex Rider's birthday is February 13th, 1987.

Caveat: April 1st, 2001 was a Sunday and while it wasn't explicitly stated as being a Monday in the book, that's the day of the week that makes the most sense based on what events happened on what days. So I've based the days of the week on the 2002 Calendar year (Bonus: April 1st was also on a Monday in 2013 and 2019).

Dates marked with a tilde (~) are approximate

STORMBREAKER

March 12 - Tuesday - Alex told about Ian’s death

March 13 - Wednesday - Ian Rider's Funeral

March 14 - Thursday - Alex almost gets compacted in Ian's car

March 15 - Friday - Alex goes to "the Bank" where he gets tranq'd

March 16 - Saturday - Briefing w/ Blunt and Jones

March 17 - Sunday - Day 1 at Brecon Beacons

March 26 - Tuesday - Killing house (day 10)

March 27 - Wednesday - Big hike (day 11)

March 28 - Thursday - Parachute, gadgets, Yassen briefing (day 12)

March 29 - Friday - Arrives at Sayle Enterprises

March 30 - Saturday - Plays with Stormbreaker

March 31 - Sunday - Yassen arrives 2am, daytime quad bike attack (claustrophobia)

April 1 - Monday - Ceremony at the science museum of london

April 2 - Tuesday - Sayle Yassassinated

POINT BLANK

April 3 - Wednesday - Alex is back at school

April 5 - Friday - Alex commits crane crimes (dissociative episode)

April 6 - Saturday - Point Blanc briefing

April 9 - Tuesday - Fiona Friend plays the most dangerous game

April 10 - Wednesday - Horse vs train (claustrophobia)

April 13 - Saturday - Meets Mrs Stellenbosch, hotel in paris

April 14 - Sunday - Arrives at Point Blanc

~April 22nd - Monday - Hits the panic button

~April 23rd - Tuesday - Captured and monologued

~April 24th - Wednesday - Alex’s 2am escape and funeral

~April 25th - Thursday - SAS raids Point Blanc

May 1 - Wednesday - Alex and Julius death match

SKELETON KEY

Note: There are major timeline problems internal to this book that have repercussions on Scorpia's timeline. This is the only way I could make it make sense with Wimbledon.

May 7 - Tuesday - Summer Term starts

May 24th - Friday - Crawley approaches Alex about Wimbledon

May 27th - Monday - Alex starts training to be a ball boy

June 24th - Monday - Wimbledon Tennis Tournament begins

~June 1st - Monday - Fights the Big Circle gangster

July 13th - Saturday - Arrived in Cornwall for vacation

July 17th - Wednesday - Jet ski attack

July 22nd - Monday - Packed off to Miami

July 23rd - Tuesday - Mayfair Lady explodes

July 24th - Wednesday - Arrived on Cayo Esqueleto

July 25th - Thursday - Scuba diving, shark racism, sugar crusher

July 26th - Friday - Sarov tells Alex about Vladimir

July 27th - Saturday - The Russian president arrives (claustrophobia)

July 28th - Sunday - Refueling stop in Edinburgh, Murmansk

August 2nd - Friday - Jones and Blunt meet to debrief

August 3rd - Saturday - Sabina invites Alex to the South of France

EAGLE STRIKE

August 10th - Saturday - Bomb at the rental (panic attack), bullfight

August 11th - Sunday - Back in London, blows it with Sabina

August 12th - Monday - Gameslayer launch party

August 13th - Tuesday - Meeting Marc Antonio in Paris

August 14th - Wednesday - Spying on Cray in Sloterdijk (claustrophobia)

August 15th - Thursday - Sabina kidnapped by Cray

August 16th - Friday - Cray’s ransom demand

August 17th - Saturday - Eagle Strike

SCORPIA

September 7th - Friday - Alex arrives in Venice

September 9th - Monday - Masquerade at the Widow’s Palace (claustrophobia)

September 10th - Tuesday - School trip leaves Venice without Alex

September 11th - Wednesday - Consanto blows up, dinner with the Widow

September 12th - Thursday - Malagosto

September 24th - Tuesday - Told he’s being sent back to England (suicidal ideation)

September 25th - Wednesday - Football team dies at Heathrow, Alex doesn’t kill Mrs Jones

September 26th - Thursday - Alex attends COBRA, sent back to Scorpia

September 27th - Friday - Invisible Sword

October 5th - Saturday - Alex debriefs, learns about his dad, and gets shot

TV Show Timelines: Season 1 and Season 3 and John & Ian Rider.

Complete Yassassination Count (for both TV and books)

Post where I talk about my methodology

[its-been-rose]

When Peggy said “I never forgot you!” And Marie said “and now no one ever will” she didn’t just drop the mic she drop kicked it into the basketball hoop on the other side of the school gym

[triptychofvoids]

yet again, my poor neglected sketchbook and askbox..

[the-healing-mindset]

View this post on Instagram

A post shared by Pedro Santos (@sourcemessages)

Welcome to November!

What a much needed message. Lately, you may be placing too much focus on the external. However, during this time it will be much better if you focus on your inner states of being. Focus on your energy. Focus on your mindset. As long as you do that, the things that seem to take up a lot of your mental bandwidth will shrink.

[fleuredelys]

𝐗𝐈𝐈. Given the fact that I'm actively working on giving Cartethyia more agency with what she can do or the tools she has at her disposal to that end, I have decided to detach her from Rover in what concerns being their sword. I'm aware why this was done and I won't get into details about it, but I believe that the two of them having the thread of a connection between one another thanks to Imperator (Cartethyia due to her origins as well as having been blessed by them and Rover for being their Arbiter) is enough to achieve that same connection we currently see one another have.

[gomzdrawfr]

wait i wanna draw raven

I will give you my kidney(1) if you do

[audio-luddite]

Not Bad.

In my wandering around the internoise I find a lot of errors. Errors of fact which in turn lead to confusion and poor assumptions.

I often comment on two dichotomies in the audio world. One is of course tube versus solid state electronics. The other is digital versus analog recording and play back. In both areas either side can provide excellent performance.

I have and appreciate both digital and analog recordings.

I have and appreciate both tube and solid state electronics.

Each are different. I have preferences. Neither is inherently bad.

Other people get wound up and committed to this side or that. Recently I read a person saying that vinyl albums have a limited frequency response so they are obviously inferior just for that. London ffrr recordings claimed up to 16khz which is pretty good, and CDs are good to 22khz ( 1/2 of 44khz or the Nyquist frequency) end of debate, so there.

The CD could easily produce up to the theoretical limit of human hearing. I think all digital methods have a similar limit as even with very high carrier frequencies they are filtered to pass nothing above 20khz. That is to facilitate low slopes in the output filters of Class D amplifiers for example. Academic for me as my hearing quits at 12 khz.

But what is the actual limit of LP frequency response? How about 45 khz. Back in the 1970s several companies tried to make quadraphonic sound. They encoded rear channel signals using a high frequency modulation on top of the normal music signal. It did not work all that well, and there were several competing standards and nobody won. But it did fundamentally work.

They produced stereo phono cartridges and LPs with 45 khz information on them using basically the methods used before and since. They made LPs with ultrasonic signals on them. They developed styli that were finer to track this information such as the Shibata which are still made.

My Signet TK7E cartridge was rated to respond to 45 khz. The better Grado cartridges also go that high. The top of the line Grado is rated to 70 khz. This is vinyl technology we have here with at least double the frequency response of digital methods. So no vinyl is not inferior in terms of frequency response potential.

We are of course talking about best case potential, but they did put this stuff out in the market. It actually worked.

Oh CDs have superior dynamic range, but like 20khz high frequency limit can you even use it? If the information is not on the recording does it even matter? LPs have enough for 95% of the time. I have a single CD with an extreme dynamic range where the quiet is very quiet, but turning it up to hear that part of the music makes the loud bit deafening. (KODO)

More recent digital methods have even better dynamic range. The actual use for that is in the recordings, not the playback.

Analog versus digital quality depends on production more than potential. In terms of best neither is. Oh MP3s suck generally as the priority there was compactness not quality. CDs, DSD, High res streams are fine.

And as far as tube versus solid lumps of semi-conductors well it is kinda the same. Computers and Class D amplifiers use MOSFET materials and those run at gigahertz. There are consumer vacuum tube amps that respond up to 100khz fine, and go down to 10 Hz as well. Either technology has far more potential performance than anyone can use.

Both types can have very low distortion. At normal listening levels the percentage is minuscule. Different voice and such is real but due to other things which to me are almost like black magic. My freshly retubed ARC amp sounds far more clear than before. It is still different than my old SS amp.

This stuff is not bad.

[takmiblog]

きれいな方形にこだわるな

方形波観測の誤解・・・周波数特性を測定したところ高い周波数にピークがあったとします。そして方形波を観測したらリンギングが生じました。これは同じことを意味しているのだということが案外理解されていません。高い周波数にピークがあるからその周波数で振動するリンギングが観測されるわけで、周波数特性のピークがなくなればリンギングも消えます。方形波でリングングが生じたということは、その振動周波数付近にピークがあるということでもあります。しかし、方形波観測では大雑把なことしかわかりませんので、問題が発見されたら手間がかかっても周波数特性を測定する必要があります。最初から非常に高い周波数まで精密に測定できているのであれば、方形波観測は不要だとさえ言えます。

きれいな方形にこだわるな・・・出力される方形波がきれいに直角と直線で構成された方形になると気持ちが良いものですが、常にそのような方形でなければならないものではありません。アンプの周波数特性がDCから無限に高い周波数まで完全にフラットであれば、（理論的には）常にきれいな方形波が出力されることになりますが、オーディオアンプは必ずどこかで減衰をさせますから、常に完璧な方形になるわけではありません。そういうことを求めたからといって良い音のアンプにはなりません。

（中略）雑誌のオーディオアンプの製作記事を見ると、オーバーシュートやリンギングが観測されるとなんとかしてそれをなくそうとする、方形波応答はとにかくきれいでなければダメみたいな認識があるようで、「オーバーシュートやリンギング＝悪」という図式が出来上がっている気がします。そうした単純思考から脱して、そもそも何のために方形波応答のチェックというものがあり、それはどんな意味があるのかについてもう少し原点に立ち戻って考えてみたらいかがでしょうか。必ずしも方形波がきれいな四角い形にならなければいけないわけではありません。

(http://www.op316.com/tubes/tips/b560.htm)

私のアンプ設計マニュアル / 基礎・応用編

測定器その７ （波形の観測）

＜１．周波数特性の概要をつかむ＞

by Tetsu Kimura

[rabidhiss]

Today’s rotation. All I have to say is try it. Throbbing Gristle might not be considered traditional driving music, but if you’re down to pretend you are in a serial killer movie, holy fuck, the Hamburger Lady delivers! If anyone has “First Annual Report” and can even send me MP3’s of the album I’d be to the moon, and will attempt to compensate in any way I can.

Noise Unit, Bill Leeb’s side project is definitely more driving music. “Response Frequency” released in 1990 is a great compliment to Front Line Assembly’s “Caustic Grip” released that same year. A lot of hardware is in use around this time before the computer as instrument started making everything sound similar.

[amywritesthings]

Amy You have been KILLIN IT!!!!!! How do you stay motivated to write?

AHHH thank you! Admittedly I did not think I'd be writing this much, but I actually deleted all of my social media minus my tumblr & discord about six weeks ago?

It forced me to stop doom scrolling (esp with the climate of the world right now, it was making me more depressed and anxious than I allowed myself to believe.) Totally removing that from my life when I'm done work gives me basically time to focus instead on what makes me happy, and I think so far it's been really helping!!

[void-occupation]

Me??? Projecting on Optimus Prime????? Blasphemy. Could never happen, you're being ridiculous. More likely than you'd think.

[verved]

love having to spend 7 hours in third party equalizer software to be able to use my headphones properly thank you sony