Altec 290-4G & Altec 288B clean diaphragm
Take off cover
Take off diaphragm and clean inner chamber
double check have any noise
2015年7月24日 星期五
2015年7月23日 星期四
Mouse auto testing machine
Mouse auto testing handle utility
Mouse spec. test setting utility
Mouse auto testing display
put mouse in test rack
Mouse move auto testing
Mouse orbit test for RF protocol package issue
analysis result
Mouse on air test for power saving issue
Mouse test finish
Mouse auto test handle front view
Mouse auto test handle rear view
Mouse auto test handle cover up view
motors and drivers inside
Slave PLC controller
Keyboard auto test machine
Keyboard type spec. setting utility.
Keyboard auto test handle utility
Keyboard auto test handle utility
Keyboard testing display
Keyboard driver code record feature
Keyboard CAM location teach utility
Keyboard two-key testing feature
Real testing movie
2015年4月9日 星期四
3-Way3 Horn speaker 號角喇叭
3-Way3 Horn speaker 號角喇叭 95db
Woofer 15'' / Mid Altec compression driver /Tweeter ribbon speaker
Altec compression driver & Horn
DAC Tube pre-amplifier
E88CC , 6JM6 PSE Tube amplifier
2015年1月19日 星期一
2014年9月29日 星期一
RIAA curve (曲線) ....音樂在聽RIAA是啥!
Recording 是指現場錄音麥克風收錄的音壓曲線.
1khz 以下很差大致是錄音麥克風低頻響應靈敏度差也就是性能差之故.
再此意指播放還原音壓低頻響應曲線要拉高之故.
Reproduce (也就是 playback curves)是指播放音樂時 LP放大器, 前極, 後極, 分音器, 喇叭 ....還原音壓曲線(profile)的總和.
2014年9月25日 星期四
Magic 2 MONO equalizer design ---這DIY怎校驗ㄚ?
LP playback curves equalizer AKEQ-2 mono
Tube in shielding case.
LP playback curves equalizer AKEQ-2 mono
Front view.
LP playback curves equalizer AKEQ-2 mono
front panel
below only ....WiKi explain what's FFRR78
78rpm playback curves
Usage
These EQ curves are presented as a table of "Bass Turnover Frequencies" and "10 kHz Gain Rolloffs". EQ Curves for Audacity can be generated from these Frequency and Rolloff values using the experimental Nyquist plug-in "78 RPM EQ Curve Generator". This plug-in is obtainable from the top of this Forum topic and requires Audacity 1.3.13 or later. Please give feedback on this plug-in, or ask for help if you need it, by replying to that Forum topic.
- Extract 78EQCurveGen.ny from the zip file downloaded from the above Forum topic.
- Place 78EQCurveGen.ny in the "Plug-ins" folder inside the Audacity installation folder, then launch or restart Audacity. For more help installing the .ny file to the correct location, click here.
- Click . You can find help inside the plug-in by choosing one of the Help options in "Select Function or Help".
- Choose the curve you want from the list below.
- Enter the values for your chosen curve for
- "Bass Turnover Frequency (Hz)"
- "10 kHz Gain Rolloff (dB)"
- "LF Shelving Frequency (Hz)" (if a value is given)
in the equivalent boxes in the plug-in dialogue. - Click "OK" in the plug-in to save the .xml file to your chosen location.
- Select some audio and choose .
- Choose "Save/Manage Curves...".
- Choose "Import...", navigate to the location where you saved the .xml file from 78EQCurveGen.ny, then "Open".
- Click "OK".
Now ...Equalization (EQ) Curves Explained
When phonograph records are made, the sound being recorded is deliberately distorted by reducing the volume of the low frequencies and increasing the volume of the high frequencies. This process, known as 'pre-emphasis', allows the low frequencies to be accommodated in the limitations of the record groove and reduces the effect of high frequency surface noise. If pre-emphasis was not carried out, the bass notes in the music would create a groove in the record that oscillated so wildly that the stylus could jump out of it on playback, and the treble notes would be drowned out by the surface noise of the stylus in the groove.
On playback, the pre-emphasis must be reversed in order to restore the original sound. This is known as 'de-emphasis' or equalization (EQ).
Modern vinyl records use a method of pre-emphasis and de-emphasis adopted by the Record Industry Association of America (RIAA) in the 1950's, and the EQ curve used is known as the RIAA curve. However, before the RIAA curve was adopted, each record label used its own EQ curve for recording and, for these records (78rpm and early vinyl), the correct EQ curve must be used for playback.
Each 78rpm EQ curve is a combination of two filter characteristics; a bass boost curve, defined by a 'Bass Turnover' (or 3dB) frequency, and a treble cut curve, defined by a '10 kHz Gain Rolloff' parameter, i.e. a defined level of treble cut at 10 kHz.
As an example, Figure 1 below shows the characteristic of the bass boost curve defined by a 500Hz Bass Turnover, and Figure 2 shows the characteristic of the treble cut curve defined by a 10 kHz Gain Rolloff of -13.7dB. These two curves, when combined, give the characteristic shown in Figure 3.
The EQ curve may also include a Low Frequency Shelving filter, (although it is absent from the definition of most 78 rpm EQ curves). This addition reduces the effect of the bass boost at very low frequencies (typically 50 or 100 Hz) in order to attenuate low-frequency noise such as turntable rumble. Figure 4 shows the effect of a 50 Hz LF shelving filter being added to the curve in Figure 3. This is in fact the RIAA standard EQ curve.
EQ Curve List
Table 1: 78rpm Playback Equalisation Curves
| Label | Series | Bass Turnover Frequency (Hz) | 10 kHz Gain Rolloff (dB) | LF Shelving Frequency (Hz) | Source |
|---|---|---|---|---|---|
| Acoustic Recording
(such as cylinders, etc..)
| 0 (or as required) | 0 (or as required) | 1 | ||
| AES | standard | 400 | -12 | 1 | |
| AFRS Transcriptions | 500 | 0 or -5 | 1 | ||
| Allegro | 750 | -16 | 1 | ||
| Allied | 500 | -16 | 1 | ||
| American Recording Society | 500 | -12 or –13.7 | 1 | ||
| Angel | 500 | -12 | 1 | ||
| Arizona | 400 | -12 | 1 | ||
| Artist | 500 | -16 | 1 | ||
| Atlantic | 500 | -16 | 1 | ||
| Audiophile | 300 | -8 | 1 | ||
| BBC Transcriptions | 1949 | 500 | -5 | 1 | |
| BBC Transcriptions | most | 250-300 | 0 to -5 | 1 | |
| Bach Guild | 501-529 | 500-750 | -16 | 1 | |
| Banner | adjust as required | 500 | -16 | 1 | |
| Bartok | 629 | -16 | 1 | ||
| Bartok | 301-304, 309, 906-920 | 700 | -16 | 1 | |
| Berliner | speed = 71.29 RPM | 0 | 0 | 1 | |
| Blue Bird | 800 | -10 | 1 | ||
| Blue Note Jazz | 400 | -12 | 1 | ||
| Blumlein | 250 | 0 | 50 | 2 | |
| Boston | COL* | -16 | 1 | ||
| Brunswick | rare | 1000 | -8.5 | 1 | |
| Brunswick | from 1946 | 300 | -16 | 1 | |
| Brunswick | early | 300-500 | 0 or -16 | 1 | |
| Brunswick | 500 | 0 | 3 | ||
| BSI 78 | 353 | -10.5 | 50 [2] | 1, 2 | |
| Caedmon | 629 | -11 | 1 | ||
| Caedmon | 1001-1022 | 700 | -12 | 1 | |
| Cameo | inconsistent, adjust as required | 1 | |||
| Canyon | 400 | -12 | 1 | ||
| Capitol | FDS | 400 | -12 | 1 | |
| Capitol-Telefunken | 500 | 0 | 1 | ||
| Capitol | 500 | -12 | 1 | ||
| Capitol | 1942 | 400 | -12 | 3 | |
| Cetra Soria | 400 | -12 or -16 | 1 | ||
| Cetra | 400 | -11 | 1 | ||
| Coliseum | 400 | -12 | 1 | ||
| Columbia* | 1925 | 200 | -7 | 1, 3 | |
| Columbia* | 1926 | 250 | -5 | 1 | |
| Columbia* | 1938-most | 300 | -16 | 1, 3 | |
| Columbia* | various | COL* | -16 | 1 | |
| Columbia* | European | 300 | -5 | 1 | |
| Columbia | English | 250 | 0 | 3 | |
| Concert Hall | 400 | -12 | 1 | ||
| Contemporary | 400 | -11 | 1 | ||
| Cook Laboratories | 500 | -11 | 1 | ||
| Cook Laboratories | binaural inside band | 500 | 0 | 1 | |
| Coral | 400 or 750 | -12 or -16 | 1 | ||
| Decca | early | 150 or 300 | 0 or -6 | 1 | |
| Decca 78 | 150 | -9 | 2 | ||
| Decca | 1946- | 400 or 500 | -12 | 1 | |
| Decca FFRR | 1949 | 250 | -5 | 1, 3 | |
| Decca FFRR | 1951 | 300 | -14 | 1 | |
| Decca | 1934 | 400 | -12 | 3 | |
| Deutsche-Grammophone | 300 | -5 | 1 | ||
| Dial | 500 or 750 | -16 | 1 | ||
| Disc | 300 | -16 | 1 | ||
| Ducretet-Thomson | 450 | -11 | 1 | ||
| EMI | 1931 | 250 | 0 | 1, 3 | |
| EMI | 33 LP | 500 | -12 | 1 | |
| EMS | 375 | -12 | 1 | ||
| Edison | 0 | 0 | 1 | ||
| Electrola | 800 | -10 | 1 | ||
| Elektra | 629 | -16 | 1 | ||
| Epic | thru 1954 | COL* or 750 | -16 | 1 | |
| Esoteric | 400 or 500 | -12 | 1 | ||
| European | 280 | 0 | 1 | ||
| Festival | 750 | -16 | 1 | ||
| FFRR 78 | 300 | -5 | 40 | 2 | |
| Folkways | 629 | -16 | 1 | ||
| Good Time Jazz | 400 | -12 | 1 | ||
| Gramophone | 300 | -10 | 1 | ||
| HMV | 1925-1946 | 250 | 0 | 1, 3 | |
| HMV | 1946 | 400 | -10 | 1 | |
| HMV | 1946-1954 | 500 or 800 | -16 | 1 | |
| HMV | American | 400 | -12 | 1 | |
| Handel Society | 750 | -16 or -17 | 1 | ||
| Haydn Society | 750 | -16 or -17 | 1 | ||
| Harmony Acoustics | thru 8/29 | 300 | -16 | 1 | |
| Hit of the Week | 500 | -5 | 1 | ||
| Kapp | 700 | -16 | 1 | ||
| Kendall | 629 | -16 | 1 | ||
| King | 500 | -16 | 1 | ||
| Linguaphone | 300 | 0 | 1 | ||
| L’Oiseau-Lyre | 500 | -10 | 1 | ||
| London | early | 300 | 0 | 1 | |
| London | up to LL846 | 500 or 750 | -10.5 | 1 | |
| London FFRR | 1949- | 250 or 280 | -5 | 1 | |
| London FFRR | 1949 | 250 | -5 | 3 | |
| Lyrichord | early | 400 or COL* | -16 | 1 | |
| Lyrichord | newer | 629 | -16 | 1 | |
| Mercury | thru 10/54 | 400 | -12 | 1, 3 | |
| MGM | 500 | 0 or -12 | 1 | ||
| MGM | 500 | -12 | 3 | ||
| Montilla | 500 | -12 | 1 | ||
| Musicraft | 750 | -14 | 1 | ||
| NAB | standard | 500 | -16 | 1 | |
| New Records | 750 | -16 | 1 | ||
| Nocturne | 400 | -12 | 1 | ||
| Oceanic | COL* or 750 | -16 | 1 | ||
| Odeon | early electricals | 700 | 0 | 1 | |
| Odeon | pre-1947 | 300 | -8.5 | 1 | |
| Oiseau-Lyre | thru 1954 | COL* | -8.5 | 1 | |
| Okeh | electricals | 300 | 0 or -8.5 | 1 | |
| Oriole | inconsistent, adjust as required | 1 | |||
| Orthoacoustic Transcriptions | 500 | -16 | 1 | ||
| Overtone | 400 or 500 | -16 | 1 | ||
| Oxford | 750 | -16 | 1 | ||
| Pacific Jazz | 400 | -12 | 1 | ||
| Parlophone | varies with era | 300 or 500 | 0 or –8.5 | 1 | |
| Parlophone | 500 | 0 | 3 | ||
| Pathe | inconsistent, adjust as required | 1 | |||
| Period | 500 | -16 | 1 | ||
| Polydor | 300 | -8.5 | 1 | ||
| Philharmonia | 400 | -12 | 1 | ||
| Polymusic | 500 | -16 | 1 | ||
| Polymusic | binaural inside band | 500 | 0 | 1 | |
| RCA Victor | early acoustics 71.29 RPM | 0 | 0 | 1 | |
| RCA Victor | later acoustics 76.59 RPM | 0 | 0 | 1 | |
| RCA Victor | 1925 78 RPM | 250 or 300 | 0 or -5 | 1 | |
| RCA Victor | 1931 LP only | 700 or 800 | 0 to –10.5 | 1 | |
| RCA Victor | 1933 | 375 | -8.5 | 1 | |
| RCA Victor | 1935 | 300 or 500 | 0 | 1 | |
| RCA Victor | 1938 | 500 | -5 | 1 | |
| RCA Victor | 1938 – 1948 | 500 | 0 to -12 | 1 | |
| RCA Victor | 1938 – 1947 | 500 | -7 | 3 | |
| RCA Victor | 1948 | 500 | -10.5 | 1 | |
| RCA Victor | 1949- | 500 | -12 or -13 | 1 | |
| RCA Victor | 1947 - 1952 | 500 | -12 | 3 | |
| Rachmaninoff Society | 750 | -16 | 1 | ||
| Radiofunken | 400 | 0 | 1 | ||
| Remington | 500 | -16 | 1 | ||
| Renaissance | 750 | -12 | 1 | ||
| RIAA | standard | 500 | -13.7 | 50 | 1 |
| Riverside | 400 | -12 | 1 | ||
| Romeo | inconsistent, adjust as required | 1 | |||
| Schirmer | 1000 | -24 | 1 | ||
| Stradivari | 750 | -16 | 1 | ||
| Supraphone | 400 | 0 | 1 | ||
| Technicord | 800 | -12 | 1 | ||
| Telefunken | 400 | 0 | 1 | ||
| Transcriptions | various, typical | 500 | -16 | 1 | |
| Ultraphone | 400 | 0 | 1 | ||
| Urania | most | COL* or 750 | -16 | 1 | |
| Urania | newer | 400 | -12 | 1 | |
| Vanguard | 411-22, 6000-18,
7001-7011, 8000-8004
| COL* or 750 | -16 | 1 | |
| Velvet Tone | acoustics to 8/29 | 300 | -16 | 1 | |
| Victor | 1925 (see RCA Victor for 1929-) | 200 to 500 | -7 | 3 | |
| Vitaphone | 950 | -18.5 | 1 | ||
| Vitaphone | motion picture | 300 | 0 | 1 | |
| Vocalion | electricals | 300 | 0 | 1 | |
| VOX | 500 or 750 | -16 | 1 | ||
| War Department | 12” Special Services | 700 | -5 | 1 | |
| Western Electric | early transcriptions | 300 | 0 | 1 | |
| Westminster | pre-1956 | 500 or 750 | -16 | 1 | |
| Westminster | “AES” printed on jacket | 400 | -12 | 1 | |
| Westrex | 200 | 0 | 1, 2 | ||
| Westrex (later) | 300 or 500 | 0 | 2 | ||
| Zonophone | early 71.29 RPM | 0 | 0 | 1 | |
| Zonophone | most | 300 | 0 | 1 |
- COL - Some recordings require a Bass Turnover of 300 Hz or 500 Hz, a 10 kHz rolloff of -16 dB and a LF Shelving filter at 100Hz.
-
- This is often referred to as a "Columbia curve".
Table 2: Pre-1955 LP Playback Equalisation Curves
| Label | Series | Bass Turnover Frequency (Hz) | 10 kHz Gain Rolloff (dB) | LF Shelving Frequency (Hz) | Source |
|---|---|---|---|---|---|
| Angel | 500 | -12 | 3 | ||
| Audio Fidelity | 500 | -16 | 3 | ||
| Bach Guild | 501-529 | 500 | -16 | 3 | |
| Bartok | 301-304, 309, 906-920 | 629 | -16 | 3 | |
| Boston | 500 | -16 | 3 | ||
| Caedmon | 1001-1022 | 629 | -16 | 3 | |
| Capitol | 400 | -12 | 3 | ||
| Capitol-Cetra | 400 | -12 | 3 | ||
| Cetra-Storia | (a)500 or (b)400 | (a)-16 or (b)-12 | 3 | ||
| Colosseum | (a)400 or (b)500 | (a)-12 or (b)-16 | 3 | ||
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