Audio-gd NFB-28 Review (w/ Jot+Modi Multibit comparison)

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by k4rstar, Dec 18, 2016.

  1. borrego

    borrego Incessant Audio-GD #1 Fan Boy

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    The TCXO upgrade option is still available from audio-gd's Chinese NFB-28 page. Not sure why it is not available in the English page. The standard SZ (Shenzhen company) XO audio-gd uses will take about 50 hours to settle.

    For audio-gd DAC/amplifier in general, they all sound "compressed" when they are not probably warm up. And with their thick gauge aluminum cases, it often take 1 to 2 hours to their amp to "properly" warm up. Using a towel to cover the ventilation slots on the case in the first 30mins of listening is my solution.
     
  2. Psalmanazar

    Psalmanazar Most improved member; A+

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    That's all amps and not what we're talking about. The full-size AGD amps have exaggerated macrodynamics for transients and tons of Chifi high fructose corn syrup bloom but no microdynamics at all.
     
  3. borrego

    borrego Incessant Audio-GD #1 Fan Boy

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    Perhaps you was hearing one of those specially requested "high gain" +20dB, +30dB models which were quite popoular in head-fi during a period of time when it seemed everyone was preparing buying HE6. My experience with "normal" gain audio-gd amp are the opposie, good micro dynamic but not a lot of slam. The audio amps I own are the SA-31SE (via RCA) and the Master 1 preamp (via CASS).

    I seldom use my SA-31SE now because it needs up to 1 hour of warm up to sound optimal (it does sound good after that), and it is with my EPA-007 stacking over it, plus using a towel covering the whole stack.

    My KA-10SH tube amp needs at most 5 mins of warm up to sound good.
     
  4. Psalmanazar

    Psalmanazar Most improved member; A+

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    Yeah I am talking about the Master 9 amp as heard in the combo (with NFB-7 DAC) NFB-27H unit.
     
  5. purr1n

    purr1n Desire for betterer is endless.

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    not tru, if u tran hard enuff, u will get skillz to do this. i have fond over tyme thru lotz of gears that my audio memry is xlent. u just need to tran. every single day do 100 push ups, 100 sit ups, 100 squats, and 10km run. then u can get skillz to do this.
     
  6. purr1n

    purr1n Desire for betterer is endless.

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    There is also a lot of crap I've heard at meets, where I give dudes (with $2000 DACs, $3200 amps, $2000 headphones, and laptops loaded with low-fidelity anime music recordings) the "are you serious?" look.

    @k4rstar: excellent comparison and you make a good point on having capable recordings to assess microdynamics.
     
  7. Grahad

    Grahad Guest

    [​IMG]

    My GIMP is rusty...
     
  8. purr1n

    purr1n Desire for betterer is endless.

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    Please, just don't use the OPM opening credits song recording to assess gear. (Unless there is an @LFF remastered version that I am not aware of).
     
  9. Ray

    Ray Friend

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    I actually thought the nfb1 was pretty good for a bit. When my bw arrived I couldn't listen to it again.
     
  10. gamerstudent

    gamerstudent Acquaintance

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    I may need to order a NFB-1AMP after my HD-6XX arrive along with a balanced cable and do an A/B comparison with a few people and hear what they say :)
     
  11. borrego

    borrego Incessant Audio-GD #1 Fan Boy

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    The best sounding "full size" headphone amps were actually the Master 5, 6 & 8 before they followed the head-fi "more power the better" trend by using the same speaker power amp 150W output transistors as in their power amps. The Master 9 using these 150W power transistors take almost forever, if not long hours to warm up when driving efficient dynamic headphones.

    Now every audio-gd balanced headphone amps, including the NFB-1AMP, are actually integrated speaker amps just like the Rag. One can just get a 4 pin XLR to speaker banana plugs conversion cables to drive unpowered bookshelf speakers with the amps.
     
    Last edited: Dec 19, 2016
  12. mrflibble

    mrflibble Friend

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    That is very interesting about the ability to drive bookshelf speakers with these amps. I assume that doing so would be sub-optimal and that the speakers would need to be an easy load?

    My NFB-1AMP is scheduled to arrive today and I still have my Jotunheim, so I will be able to perform a head-to-head comparison. A couple of caveats, (1) I no longer have my Modi Multibit therefore the comparison will be done with Gungnir Multibit and (2) I'm recovering from a flu bug and my sinuses / hearing is slightly compromised.
     
  13. borrego

    borrego Incessant Audio-GD #1 Fan Boy

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    The NFB1AMP is rated at 9.9W per channel driving 25ohm load. I would estimate it will output at least 25W per channel driving 8ohm load.

    Just cover the NFB1AMP with a towel the 1st 30mins of your listening to speed up warm-up. Towel is good friend of every audio-gd gear.
     
  14. sphinxvc

    sphinxvc Gear Master (retired)

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    Better yet, microwave it. :rolleyes:

    [don't actually do this]
     
  15. borrego

    borrego Incessant Audio-GD #1 Fan Boy

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    Well, actually there is another way requiring a bit more works.

    Replace the stock OPA2134 DC servo opamp with OPA2140. You have to do some SOIC-DIP8 conversion board soldering, open the case, pull the stock opamps out and press in the your DIY ones. There are 4 DC servo opamps for every audio-gd CASS balanced amp, 2 DC opamps for non-balanced amp.

    I did this to my Master 1 preamp and it cuts warm up time from 45mins to 15mins (for optimal sound that is). Side effect is better bass definition and improved transparency.
     
    Last edited: Dec 30, 2016
  16. borrego

    borrego Incessant Audio-GD #1 Fan Boy

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    [​IMG]

    [​IMG]

    Not sure if audio-gd shall still honor warranty for the amp though.
     
  17. thegunner100

    thegunner100 Hentai Master Chief

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    Guys... just leave the damn amp on -_-
     
  18. mrflibble

    mrflibble Friend

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    Yes a towel is a very useful thing to have around, one never knows when one may need one:

    — Douglas Adams, The Hitchhiker's Guide to the Galaxy
     
  19. zonto

    zonto Friend

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    New Audio-gd slogan?

    [​IMG]
     
  20. Grahad

    Grahad Guest

    Give us 5 star reviews and we'll give you PCM1704UK towels perhaps. Stock in an emergency!
     

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