McIntosh MA7000s hodetelefonforstermodul + hodetelefonmatchberegninger
Jeg gjorde noen beregninger i august for McIntosh MA7000 (se nedenfor i separat innlegg). Den passer til mange av mine hodetelefoner, spesielt hvis man ikke har behov for ekstra høye lydstyrkenivåer. Jeg tror AKG K 701 var den minst egnede (i betydningen antagelig for lite effekt for dens inngangsimpedanse og sensitivitet jfr.
NwAvGuys tall for moderate lydstyrkenivåer) mens Denon AH-D7000 var ganske akkurat p.g.a. sin lave inngangsimpedanse. Det kan dog tenkes at også AKG K 701 går greit for min del siden jeg lytter med
høyst moderate lydstyrkenivåer. Hvis jeg ikke husker helt galt, har Eva Cassidy + McIntosh MA7000 + AKG K 701 gitt meg gåsehud. McIntosh MA7000s hodetelefonforstermodul er altså ganske allsidig og medgjørlig. Jeg tror dog neppe at den passer relativt lavimpedante, lavsensitive ortodynamiske hodetelefoner, men jeg har ikke kontrollregnet, enn si forsøkt.
Nedenfor følger en del resultater og bakgrunnsinformasjon fra mine beregninger i august 2012 ang. ulike hodetelefoner og McIntosh MA7000 hodetelefonforstermodul. Informasjonen bør antagelig egentlig redigeres og presenteres bedre, men denne enkle presentasjonen er første forsøk.
http://www.hifisentralen.no/forumet/hodetelefoner/64131-vanskelig-valg.html#post1386261
The MA7000 headphone amp is typical of recent model preamps. The MCDs have a stronger amplifier and I will let Ted give you their characteristics.
The output impedance is less than 1 ohm, rising to 5 ohms at 20kHz and 15 ohms at 20Hz.
Power output is approximately:
600 ohms - 100mW
200 ohms - 150mW
100 ohms - 80mW
50 ohms - 40mW
25 ohms - 20mW
Jeg tror aldri jeg har sett andre produsenter oppgi hodetelefonforsterkerutgangsimpedanse ved flere signalfrekvenser. Det normale er vel kun 1 kHz(?)
Frekvens
| Utg.imp.
| Passer htlf. inng.imp.
|
20 Hz
| 15 ohm
| 120 ohm
|
1 kHz?
| < 1 ohm
| < 8 ohm
|
20 kHz
| 5 ohm
| 40 ohm
|
Klarer 110 dB
Effektbehov (ved angitt hodetelefoninngangsimpedanse) for å oppnå 110 dB:
- beyerdynamic T 1 (683 ohm): 27,8 mW
- Sennheiser HD 800 (361 ohm): 16,2 mW
- Sennheiser HD 800 (jfr. Sennheiser: 300 ohm): 16,7 mW
- Denon AH-D7000 (25 ohm): 11,2 mW
- Denon AH-D7000 (2012, 24 ohm): 15 mW
- Audio-Technica ATH-W3000ANV (jfr. A-T: 40 ohm): 6,3 mW
- Ultrasone Edition 8 (33 ohm): 12,8 mW
- JVC HP-DX1000 (jfr. Audio Cubes: 64 ohm): 6,3 mW
Klarer ikke 110 dB og bare kanskje 105 dB
- 110 dB: AKG K 701 (65 ohm): 157,5 mW
- 105 dB: AKG K 701 (65 ohm): 49,8 mW
Beregninger
Måledata er hentet fra InnerFidlity hvis annet ikke er nevnt:
http://www.innerfidelity.com/headphone-data-sheet-downloads
Sennheiser HD 800:
Sennheiser HD 800 (jfr. Sennheiser):
Nominal impedance 300 Ohm
Sound pressure level at 1 kHz 102 dB SPL (1kHz, 1 Vrms )
Sennheiser HD 800 (jfr. Sennheiser): 16,7 mW
Sennheiser HD 800:
Volts RMS required to reach 90dB SPL: 0.242 Vrms
Impedance @ 1kHz: 361 Ohms
Power Needed for 90d BSPL 0.16 mW
SPL at 1 Volt = 90 + 20 * LOG ( 1 / 0,242 ) = 102,32369268039137446571722325579
Voltage RMS = Antilog ( ( 110 – SPL at 1Vrms) /20 ) = 2,42
Power in Watts = ( V * V ) / Impedance = 16,2 mW
beyerdynamic T 1:
Volts RMS required to reach 90dB SPL: 0.436 Vrms
Impedance @ 1kHz: 683 Ohms
Power Needed for 90d BSPL 0.28 mW
SPL at 1 Volt = 90 + 20 * LOG ( 1 / 0,436 ) = 97,210270214628279487440178058743
Voltage RMS = Antilog ( ( 110 – SPL at 1Vrms) /20 ) = 4,36
Power in Watts = ( V * V ) / Impedance = 27,8 mW
AKG K 701:
Volts RMS required to reach 90dB SPL: 0.320 Vrms
Impedance @ 1kHz: 65 Ohms
Power Needed for 90d BSPL 1.57 mW
SPL at 1 Volt = 90 + 20 * LOG ( 1 / 0,320 ) = 99,897000433601880478626110527551
Voltage RMS = Antilog ( ( 110 – SPL at 1Vrms) /20 ) = 3,2
Power in Watts = ( V * V ) / Impedance = 157,5 mW
Voltage RMS = Antilog ( ( 105 – SPL at 1Vrms) /20 ) = 1,7994922406091170572638433272847
Power in Watts = ( V * V ) / Impedance = 49,8 mW
Denon AH-D7000:
Volts RMS required to reach 90dB SPL: 0.053 Vrms
Impedance @ 1kHz: 25 Ohms
Power Needed for 90d BSPL 0.11 mW
SPL at 1 Volt = 90 + 20 * LOG ( 1 / 0,053 ) = 115,51448260798421908734015416745
Voltage RMS = Antilog ( ( 110 – SPL at 1Vrms) /20 ) = 0,53
Power in Watts = ( V * V ) / Impedance = 11,2 mW
Volts RMS required to reach 90dB SPL: 0.060 Vrms
Impedance @ 1kHz: 24 Ohms
Power Needed for 90d BSPL 0.15 mW
SPL at 1 Volt = 90 + 20 * LOG ( 1 / 0,060 ) = 114,43697499232712734982466404041
Voltage RMS = Antilog ( ( 110 – SPL at 1Vrms) /20 ) = 0,6
Power in Watts = ( V * V ) / Impedance = 15 mW
Ultrasone Edition 8:
Volts RMS required to reach 90dB SPL: 0.065 Vrms
Impedance @ 1kHz: 33 Ohms
Power Needed for 90d BSPL 0.13 mW
SPL at 1 Volt = 90 + 20 * LOG ( 1 / 0,065 ) = 113,74173286714288852014467473564
Voltage RMS = Antilog ( ( 110 – SPL at 1Vrms) /20 ) = 0,65
Power in Watts = ( V * V ) / Impedance = 12,8 mW
Audio-Technica ATH-W3000ANV (jfr. Audio-Technica):
Sensitivity 102 dB/mW
Impedance 40 ohms
Antilog ( ( 110 - 102) / 10 ) = 6,3 mW
JVC HP-DX1000 (jfr. Audio Cubes):
Rated impedance: 64 Ohms
Output overpressure value: 102dB/1mW
Antilog ( ( 110 - 102) / 10 ) = 6,3 mW
Andre hodetelefoner med InnerFidelitys 90 dB-målinger
beyerdynamic T 5 p
Volts RMS required to reach 90dB SPL: 0.055 Vrms
Impedance @ 1kHz: 34 Ohms
Power Needed for 90d BSPL 0.09 mW
Fostex TH 900
Volts RMS required to reach 90dB SPL: 0.062 Vrms
Impedance @ 1kHz: 26 Ohms
Power Needed for 90d BSPL 0.15 mW
Ultrasone Signature Pro
(Kort omtale:
http://www.innerfidelity.com/content/innerfidelity-august-update-0)
Volts RMS required to reach 90dB SPL: 0.033 Vrms
Impedance @ 1kHz: 35 Ohms
Power Needed for 90d BSPL 0.03 mW
HiFiMAN HE-500
Volts RMS required to reach 90dB SPL: 0.310 Vrms
Impedance @ 1kHz: 47 Ohms
Power Needed for 90d BSPL 2.04 mW
Audeze
InnerFidelity har målt mange Audeze. Benytter de fra test 01.08.2012:
http://www.innerfidelity.com/content/spectacularly-yummy-audeze-lcd-2-and-lcd-3
http://www.innerfidelity.com/images/AudezeLCD2sn53211704circa2012.pdf
http://www.innerfidelity.com/content/spectacularly-yummy-audeze-lcd-2-and-lcd-3-measurements
Measurements of Current Audeze Headphones
Audeze LCD2 Rev. 2
http://www.innerfidelity.com/images/AudezeLCD2sn53211704circa2012.pdf
Volts RMS required to reach 90dB SPL: 0.209 Vrms
Impedance @ 1kHz: 59 Ohms
Power Needed for 90d BSPL 0.75 mW
Audeze LCD3
http://www.innerfidelity.com/images/AudezeLCD3Rev2sn2613375circa2012.pdf
Volts RMS required to reach 90dB SPL: 0.196 Vrms
Impedance @ 1kHz: 58 Ohms
Power Needed for 90d BSPL 0.66 mW
Bakgrunnsinformasjon og formler
http://nwavguy.blogspot.no/2011/09/more-power.html
Sennheiser HD600: Sound pressure level (SPL) 97 dB (SPL) at 1 mW, 300 ohms
Sennheiser HD650 - Sound pressure level (SPL) 103 dB (1 Vrms), 300 ohms
Antilog = 10x
Antilog ( ( 110 – 103) /20 )
Power in mW = Antilog ( ( Desired SPL - SPL at 1 mW ) / 10 )
90 dB Voltage to SPL at 1 Volt: SPL at 1 Volt = 90 + 20 * LOG ( 1 / V90db )
Voltage RMS = Antilog ( ( Desired SPL – SPL at 1Vrms) /20 )
Voltage to Power : Power in Watts = ( V * V ) / Impedance