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

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    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. :)
     
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  2. purr1n

    purr1n Finding his inner redneck

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    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.
     
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  3. Ringingears

    Ringingears Honorary BFF

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    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

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    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

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    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.
     
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  6. dasman66

    dasman66 Almost "Made"

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    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.
     
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  7. gixxerwimp

    gixxerwimp Professional tricycle rider

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    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.
     
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  8. gixxerwimp

    gixxerwimp Professional tricycle rider

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    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.


     
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  9. atomicbob

    atomicbob dScope Yoda

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    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.
     
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  10. Hands

    Hands Overzealous Auto Flusher - Measurbator

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    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

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    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

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    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
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  13. EraserXIV

    EraserXIV Friend

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

    PrismaticOrb Rando

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    Can low impedance planars like ether or lcdx be run on the zdt jr without damaging the drivers?
     
  15. Ash1412

    Ash1412 Friend

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    I don't see how they'd get damaged but it definitely won't be optimal as the zdt jr's output impedance is not sub 1-Ohm.
     
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  16. StageOne

    StageOne Friend

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    Has any found a good source for the rear driver tubes? I have one going bad and I'd like a backup. I tried to order a set off eBay shortly after I received my ZDT but got burned, no delivery. I know there are quite a few other sellers but I'm looking for somewhere else. I've tried about a dozen online stores in the US/EU and I can't find anyone that has them in-stock or even listed (6n24P, 6FC7, ECC89). Any leads would be greatly appreciated.
     
  17. yotacowboy

    yotacowboy McRibs Kind of Guy

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    I ordered a backup sleeve of Tesa ECC89s after I got my ZDT from this guy on eBay for peace of mind. Not seeing them in stock now, so maybe get in touch with him. I plugged them in just to make sure they weren't noisy/duds and they were just a touch less hazy sounding than the stock tubes (flying pangus/rocket/voskhod i think?) so they stayed. There's also Amazon.

    Since I picked up 5 of the Tesa's, let me know if you can't track anything down - I'd be happy to let a pair go.
     
  18. Ringingears

    Ringingears Honorary BFF

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    I’m using a pair of TESA’s from the same seller. I kept them in as I like them better than stock. Not an incredible difference. The tubes have no noise, dead quite.
     
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  19. StageOne

    StageOne Friend

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    Thank for the recommendation and offer of tubes. He didn't have any listed, but responded in about 10mins and posted a set for sale. They are not the TESA's but Procomm made in the UK. Interested to hear how they sound compared to the stock tubes. Also picked up a set of Toshiba/Tektronix 6AK5s.

    I hadn't even thought to check Amazon, but those prices are high. Then again if you actually receive them maybe it's not that bad.
     
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  20. Ty89m

    Ty89m Rando

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    Perhaps not the best thread to ask - but I’d ordered the ZDT jr. for my 800’s and 650’s, but appears they goofed and amp was actually out of stock. Drop are not particularly confident in more becoming available.

    Is there something I should look to as a suitable alternative? Below $1000 if doable. Would really like to add a nice(ish) tube amp to the collection, and a bit disappointed these are no longer available.

    Thanks!
     
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