Disappearing Headphone Jack Output

Discussion in 'Solid State' started by jdmccall, Feb 12, 2018.

  1. jdmccall

    jdmccall Well-Known Member

    Messages:
    903
    Location:
    SW Missouri, USA
    So...I bought a Parasound 2250 v.2 to up the power to my Bose 901's. Everything was fine until I went for a little headphone listening session and discovered there was no more sound to be had from the headphone jack on my NAD C 326. I disconnected the amp and re-inserted jumpers from 326 pre-outs to main-ins. Sound was restored. OK, now what? Luckily, the Parasound amp has a loop output, so I connected that back to the main input on the integrated. In retrospect, I guess it was no big deal, but I was a bit worried that when I powered up after connecting amp back to integrated that sparks would fly, or worse, when I powered up. Still, seems like an odd way for NAD to do things; to provide pre-outs that bypass the headphone jack. :dunno: Just glad I have my hp jack back :music: and that nothing blew up! :thumbsup:
     

     

    Please register to disable this ad.

  2. glen65

    glen65 Member

    Messages:
    4,382
    Location:
    Richland county, Ohio
    The headphone jack is driven by the main amp through a pair of resistors, not the preamp. That's why you lost your headphones when pulling the jumpers. This is the way most all receivers and integrated amps have it set up.
     
    Bill Ferris likes this.
  3. cademan

    cademan Addicted Member

    Messages:
    8,833
    Yup, the above is correct. :thumbsup:

    Not being familiar with Parasound equipment, does it have a headphone jack?
     
  4. jdmccall

    jdmccall Well-Known Member

    Messages:
    903
    Location:
    SW Missouri, USA
    I guess I've never driven a separate amp with the pre-out of an integrated amp or receiver before, so the issue never came up. Some amps have dedicated headphone sections but obviously not my little NAD. o_O Still, it seems like the wrong way to go about things. I suppose it's cheaper, though.

    No. It's just a basic power amp. Makes Bose 901's sing, though! :biggrin:
     
  5. cademan

    cademan Addicted Member

    Messages:
    8,833
    They make boxes for direct speaker inputs for multiple speaker outputs along with headphone jacks. Even some preamps have powered headphone jacks. Just something to look into. :thumbsup:
     
  6. Lavane

    Lavane AK Subscriber Subscriber

    Messages:
    6,832
    Location:
    northern cal.
    All of the SS integrated amps I have connect the headphones from the amp section. Even a few preamps due to the speaker switching being in the preamp. Only one of my preamps has it's own seperate headphone amp built in and it isn't tied in with the tone controls.
     

     

    Please register to disable this ad.

  7. the skipper

    the skipper Amateur Curmudgeon Subscriber

    Messages:
    2,133
    Location:
    Aggieland
    I've got a NAD 1600 tuner/pre-amp which has a headphone output, and it drives my Sennheiser 580's quite well. It's disappointing that more supposedly "high end" pre-amp manufacturers don't bother with this. After all, with economies of scale, how much could incorporating a "decent" headphone stage add to the cost?

    nad_1600.jpg
    NAD `1600 detail.jpg
     
    Last edited: Feb 13, 2018
  8. glen65

    glen65 Member

    Messages:
    4,382
    Location:
    Richland county, Ohio
    The preamp by itself isn't enough to drive the headphones anyway. Units which don't use the power amp section, have an additional dedicated stage for the headphone jack. For example, the NAD 1600 the skipper posted has a dedicated stage for the headphones. They run the preamp signal to the input of an op amp IC. Then the output from the op amp goes to the headphone jack.

    Below is how most all receivers an integrated amps have it set up.
    [​IMG]
     
    Last edited: Feb 13, 2018
  9. WillVT

    WillVT Well-Known Member

    Messages:
    924
    Location:
    Burlington, VT
    You could also use a couple of Y connectors from the preamp out. Send one to the Parasound, and the other back into the main in. I guess this would be similar to using the loop from the Parasound, but maybe fewer wires.
     
    Lavane likes this.
  10. jdmccall

    jdmccall Well-Known Member

    Messages:
    903
    Location:
    SW Missouri, USA
    I had considered the Y-connector solution but I thought the loop output from the Parasound might be simpler and less cluttered. But, a Y-connector with male input and a male and female output might be the ideal way to go, assuming someone makes such a thing, just to shorten up the signal path when listening with headphones.
     
  11. keilau

    keilau AK Member

    Messages:
    423
    Location:
    Windy City
    In recent years, headphone users have discovered that they can get audiophile quality sound and stage from high end headphones that can match speakers costing 10 times more. But a high quality headamp is a required component. The padded down power amp headphone jack is no longer acceptable. But a high quality headamp is expensive to implement so many manufacturer gave it up completely.

    If you stays with NAD, the newest NAD C165BEE has dedicated headphone amplifier using the high power TI TPA6120A2 IC specifically designed for headamp. It has high voltage and current capacity to drive 32-600 ohms headphones. Is it as good as discrete transistor class A headamp? TI claims that it is and it looks good on paper. The TPA6120A2 has current-feedback AB amplifier architecture delivering high bandwidth, extremely low noise, and up to 128dB of dynamic range. It is much better than low power headamp IC in older mid range preamps, including that in the NAD 1600, for sure.


    The NAD 1600 uses a NJM2043D IC for its headphone amplifier, making it sound reasonable good compared to the padded down power amp jack. But it is no long good enough in today's market. You can find the NJM2043D or NJM4556D in many preamp from the mid 1980's.
     
    Last edited: Feb 13, 2018

     

    Please register to disable this ad.

  12. the skipper

    the skipper Amateur Curmudgeon Subscriber

    Messages:
    2,133
    Location:
    Aggieland
    Thanks for your kind opinion, kelly. You worded that exactly like one would expect of one of them thar "audiosnobs" of which we laugh about. I guess my being satisfied with it makes me a tone deaf troglodyte in your book, right?

    Here's a hint: Sometimes, it's not always what you say but how you say it.
     
    Last edited: Feb 13, 2018
  13. BMWCCA

    BMWCCA AK Subscriber Subscriber

    Messages:
    5,342
    Location:
    Virginia
    My Soundcraftsmen pre-amps all have headphone jacks. I've used them for years and they sound fine with low-impedance headphones like my Sennheiser HD 598s. In fact, they sound fine through the headphone jack on my Nakamichi Dragon tape deck. In addition, all of my Crown amps have "monitor" outputs for headphones, and so do the Crown PSL pre-amps I use in my second and third systems. Not sure what the big deal is with headphone amps when I get great sound quality from the jacks on nearly every component. Not that I haven't tried headphone amps. Our local Crutchfield store has a fine headphone test station which includes a variety of headphone amps. That's where I first heard the 598s. :dunno:
     
  14. avionic

    avionic " Black Knights " Subscriber

    Messages:
    40,096
    Location:
    Fort Dodge, Iowa
    All of Yamaha control amplifiers have a built in headphone amp.
     
  15. the skipper

    the skipper Amateur Curmudgeon Subscriber

    Messages:
    2,133
    Location:
    Aggieland
    I think the OP's main issue is that he bought an integrated amp, not a separate preamp and power amp pair and, as such, was intended to be used with it's internal power amp. That it allows the pre/main stages to be separated is a nice, handy feature but being used as a pre-amp wasn't it's main design goal.

    But, if the headphone is really that important, a pair of "Y" splitters on the pre-amp output with one side going to the power amp and the other to a standalone headphone amp will solve the problem.

    But, hey, what do I know about pre-amps? The only other standalone pre-amp I've owned is a Marantz Model 7C and I'm pretty sure thing shave changed since then.
     
    Last edited: Feb 13, 2018
  16. keilau

    keilau AK Member

    Messages:
    423
    Location:
    Windy City
    If you are happy with the headphone jack on the NAD 1600, enjoy it and do not allow others to tell you otherwise.

    I used the NAD 1600 for a few years and remember the sound of its headphone jack. If you believe that anyone one who believes that a dedicated headamp sounds different is an "audiosnobs", you are entitled to your opinion.

    Who are the "we" that you mentioned?
     
    Last edited: Feb 13, 2018

     

    Please register to disable this ad.

  17. the skipper

    the skipper Amateur Curmudgeon Subscriber

    Messages:
    2,133
    Location:
    Aggieland
    Don't worry. In my over 60 years in this hobby I've learned to not let others opinions tell me what to like and not like. I may take their suggestions and give a listen but will ultimately make my own decisions what suits me.

    "We" would be those who rile when it seems that someone is belittling others for their likes or preferences. That, to me, is the definition of an audiosnob.

    Please note that I never said the headphone output on the 1600 was the was the ne plus ultra, but that it simply satisfied my needs.

    I repeat: It's not always what one says but how they say it.
     
    Last edited: Feb 13, 2018
  18. jdmccall

    jdmccall Well-Known Member

    Messages:
    903
    Location:
    SW Missouri, USA
    Affordable, new pre-amps are so rare today. Which is how I ended up buying an int. and using it as a pre. It's about half the price of the NAD C 165 pre-amp. True enough, I didn't consider the hp issue. Didn't know it would even be an issue, for that matter.

    But I'm getting by just fine now. The line-out from the Parasound amp back into the integrated's main-in works great for me.
     
  19. keilau

    keilau AK Member

    Messages:
    423
    Location:
    Windy City
    Which Parasound Integrated did you get? How does it work out for you? When I look for a preamplifier recently, I thought about the Parasound Halo Integrated until I found out it costs 3 times more than the NAD C165. In deed, Affordable new preamplifier are rare. I suspect that separated preamp market is small and manufacturer can make a profit only in the higher end market. I found a few used NAD C165, Parasound 2100 in the $400-600 range, but did not buy.

    I ended up getting a 20 years used Harman Kardon AP2500 preamplifier, which has the very high quality MC phono stage that I was looking for. As a bonus, the Harman Kardon AP2500 preamplifier also have a high power discrete headphone amplifier which is another rarity in the under $1K preamp.
     
  20. jdmccall

    jdmccall Well-Known Member

    Messages:
    903
    Location:
    SW Missouri, USA
    I have an NAD C 326 int. amp. I added a Parasound 2250 v.2 power amp, which killed the headphone jack until I looped back a line-level output from the Parasound
    into the NAD's main-in jacks.
     

Share This Page