Massdrop x Eddie Current ZDT Jr. (Official Thread)

Discussion in 'Headphone Amplifiers and Combo (DAC/Amp) Units' started by Hands, Nov 15, 2017.

  1. Hands

    Hands Overzealous Auto Flusher - Measurbator

    Staff Member Friend MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    8,370
    Dislikes Received:
    25
    Trophy Points:
    113
    Location:
    Colorado
    Home Page:
    Cool, yeah, try going straight Modi -> NBM, nothing else in the chain, no bypasses to other amps, etc. See if that affects anything at all. Just humor me. It might not affect anything!

    Well, this is more about trying to solve a longstanding mystery where some would hear the NBM/ZDT Jr as having rolled bass (or super poor quality bass) and some wouldn't. Normally this would be fine, except I haven't been able to match this up to user tastes and experiences. Like I've put my ZDT Jr up against the Magni 3 and not heard a bass roll off, so I can't even triangulate ZDT Jr impressions consistently against well known gear.

    Yeah, I tested two other ZDT Jrs, the loaner units, because impressions were so inconsistent, and they more or less sounded the same. Some slight tube differences, but the channel balance/imbalance on each unit's pot had a slight acoustic effect as well.

    And you took my jab in stride and responded appropriately. Friends should be able poke fun at each other. :)
     
    gixxerwimp and Lyer25 like this.
  2. purr1n

    purr1n Finding his inner redneck

    Staff Member Friend BWC
    Joined:
    Sep 24, 2015
    Likes Received:
    47,126
    Dislikes Received:
    73
    Trophy Points:
    113
    Location:
    Antarctica
    FWIW, I'm hearing the same things you are hearing. Mid-bass is present but wooly. Bottom octave 20-40Hz sounds, well, as you said, more like distortion elements. The third bass note (37Hz) in Daft Punk's Doin' It Right that I so often refer to sounds like a soft fart.

    FR will probably not tell us much. THD was 0.55% at a moderate-high 0.55Vrms level at 30Hz. I imagine if the signal level was even pushed even up a bit, things would have turned into shit rapidly. I tend to let these things slide for cheap tube amps. The mids on up is where it is at. I believe this is where @Hands and I are coming from. We know it's a certain kind of amp and will perform a certain way. It's like criticizing a heavy car for not being nimble in the mountains or a low displacement 4-cylinder for not having any low-end torque.
     
    gixxerwimp and Lyer25 like this.
  3. Ringingears

    Ringingears Honorary BFF

    Friend
    Joined:
    Sep 26, 2015
    Likes Received:
    3,314
    Dislikes Received:
    2
    Trophy Points:
    113
    Location:
    Northern Californium Valley
    I hope the mystery gets solved. I don’t hear a bass roll off on my unit, and I have heard other amps that have that issue, and headphones too. Confusing.

    Edit: perhaps it’s because I don’t play much music that has low bass notes. I’ll have to check further.
     
  4. purr1n

    purr1n Finding his inner redneck

    Staff Member Friend BWC
    Joined:
    Sep 24, 2015
    Likes Received:
    47,126
    Dislikes Received:
    73
    Trophy Points:
    113
    Location:
    Antarctica
    The use of higher Z dynamic cans such might exacerbate the issue because of bumped up bass from Zout interactions. The lower bass volume gets reduced in relation to mid-bass compared to say a Magni 3. I also figure its @gixxerwimp selection of recordings. Most recordings have very little below 40-50Hz (just look at a spectrum analyzer while music is playing or do a spectrum analysis in Adobe Audition, Audacity, etc.) EDM material can actually have real low bass notes depending upon sub-genre.
     
  5. Hands

    Hands Overzealous Auto Flusher - Measurbator

    Staff Member Friend MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    8,370
    Dislikes Received:
    25
    Trophy Points:
    113
    Location:
    Colorado
    Home Page:
    Yeah, but I don't think that's unique to the ZDT Jr. Plenty of amps that perform somewhat similarly in the bass without too many complaints. Or at least complaints would be consistent between a user's tastes and gear experience/comparisons.

    ZDT Jr impressions are just wildly all over the place compared to other gear.
     
    Lyer25 likes this.
  6. dasman66

    dasman66 Almost "Made"

    Contributor
    Joined:
    Mar 13, 2018
    Likes Received:
    225
    Dislikes Received:
    2
    Trophy Points:
    43
    Location:
    NW Pennsylvania
    Wow, I didn't realize it made a difference... now I'm going to have to listen to both my amps without the sys and see if I can hear a discernible difference.

    I run the MCTH volume at 1:30, the Mogwai at about 10:30 and the sys is down at 9:00. I might blow my ears out without the sys, but I'll give it a shot and see if I hear a difference.
     
    gixxerwimp likes this.
  7. gixxerwimp

    gixxerwimp Professional tricycle rider

    Friend
    Joined:
    Sep 30, 2015
    Likes Received:
    1,860
    Dislikes Received:
    13
    Trophy Points:
    113
    Location:
    small island claimed by China
    A little OT wrt this thread, but might clarify SYS issues discussed for some, and rule out any holistic interactions that might be going on.
    https://www.superbestaudiofriends.o...purpose-advice-thread.19/page-296#post-187211

    Running SYS backwards might not make things sound weird, but the pot behaviour is definitely out of wack and you lose fine control at lower volume levels IIRC.

    @Hands I didn't get around to taking SYS out of the chain last night. And won't tonight as I'm off to the electronics market to hunt down a non-scratchy replacement ALPS pot for MCTH.
     
    msommers likes this.
  8. gixxerwimp

    gixxerwimp Professional tricycle rider

    Friend
    Joined:
    Sep 30, 2015
    Likes Received:
    1,860
    Dislikes Received:
    13
    Trophy Points:
    113
    Location:
    small island claimed by China
    I hear the exact same thing type of bass with Clear out of low Z as well, worse out of high Z as they get that mid-bass bump. I don't usually listen to those *starred recordings and only use them to test sub-bass response and quality. A lot of EDM tracks sound pretty good out of ZDTjr, as long as there aren't any pure sub-bass tones. Both these tracks are bass heavy and sound decent.


     
    direstraitsfan98 likes this.
  9. atomicbob

    atomicbob dScope Yoda

    Friend BWC MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    9,285
    Dislikes Received:
    3
    Trophy Points:
    113
    Location:
    On planet
    Several observations.

    First, from the discussion in the Eddie Current ZDT Jr. Technical Measurements thread:
    This amplifier has some interesting properties, especially in the distortion measurements. The distortion signature changes with level. Depending on personal preference, headphones and listening sound levels this amplifier will sound markedly different. Pay particular attention to spectrums measured at 0, -10 and -20 dBu. They are presented together for easy comparison.

    Second, this amp has considerably different behavior at 30 ohms load than at 300 ohms.

    Third, small output transformers typically will magnetically saturate at lower signal levels than large output transformers at low frequencies.

    A consideration typically missing from posted listening evaluations is the listening level. From the headphone used impedance, sensitivity and FR may be determined. But no one reports either the output voltages to the headphones or SPL directly measured from the headphones using either a cal tone or pink noise.

    It may be that conflicting observations are from differing sound levels preferred by the listeners evaluating the amp.
     
    sphinxvc, hikergrl, Ash1412 and 10 others like this.
  10. Hands

    Hands Overzealous Auto Flusher - Measurbator

    Staff Member Friend MZR
    Joined:
    Sep 27, 2015
    Likes Received:
    8,370
    Dislikes Received:
    25
    Trophy Points:
    113
    Location:
    Colorado
    Home Page:
    Let it be known, I like to listen loud as fuck, for better or worse (in regards to my hearing or gear performance).

    Going to RMAF showed me how quietly people listen. And a lot of times when people say, "Oh, yeah, I listen loud," they don't. And I know this because I just put on the headphone they just tested without adjusting the volume before walking off.

    The only time I nearly shit my pants due to listening volume was when I tested the RAAL SR1a at RMAF. Whoever had the volume control at that booth probably had severe hearing loss and wanted to jam out as best as they could. I was more impressed to see someone not afraid to pussyfoot around with volume knobs.
     
  11. gixxerwimp

    gixxerwimp Professional tricycle rider

    Friend
    Joined:
    Sep 30, 2015
    Likes Received:
    1,860
    Dislikes Received:
    13
    Trophy Points:
    113
    Location:
    small island claimed by China
    Thanks for pointing this out, Bob. I found "50 Hz + 7000 Hz spectrum" at 0dBU and -10dBu for 30R and 300R loads (no -20dBu). It looks like the relative and absolute amounts of harmonic distortion vary with sound level, but I'm not able to interpret beyond this.

    I do tend to listen on the quieter side. But when testing the low freq response using the test tracks listed, I listened both at my normal levels and also cranked up as loud as I could bear. For example, the intro on Silent Shout is just LF and I would have it loud enough that if I didn't turn it down when the keyboards come in (0:22) I'd be ripping the cans off my head. So my impressions are for both "normal" and "loud as fuck" levels.
     
  12. gixxerwimp

    gixxerwimp Professional tricycle rider

    Friend
    Joined:
    Sep 30, 2015
    Likes Received:
    1,860
    Dislikes Received:
    13
    Trophy Points:
    113
    Location:
    small island claimed by China
    Thanks for the recommendation. I bought these Raytheon JRP-5654s and so far am very pleased. In addition to having tighter, more extended bass than the GEs, treble is smoother, they're a touch less forward, and seem to be extracting more plankton. There was a slight volume/distortion imbalance in the bass when I first plugged them in, but after 24 hrs of burn in that seems to have gone.

    Edit: ebay link for those who can't see the embedded url.
    https://www.ebay.com/itm/262396446387
     
    Last edited: Aug 16, 2019 at 5:16 PM
    StageOne and Ksaurav402 like this.
  13. EraserXIV

    EraserXIV Friend

    Friend
    Joined:
    Oct 7, 2015
    Likes Received:
    173
    Dislikes Received:
    0
    Trophy Points:
    43
    Location:
    Las Vegas

    What is the white film layer that is between the transformer and the steel sheets on the official Massdrop fix?
     

Share This Page