[JNKM]

Haven't seen too many impressions of the ZDT Jr. after the last round of deliveries, so I thought I'd share my two cents, for what it's worth.

Well, after spending some time with this amp, it ultimately wasn't to my tastes. Even if I were to ignore the humming issue, which my unit was not immune to, I just could not get used to the way it sounded -- with both of my headphones (Atticus and HD650) -- and this is with the better GE tubes (JAN 5654W). Perhaps it was a synergy issue or perhaps it just didn't match my personal sound preferences, but long story short, my issues with the sound, as I heard it, were essentially two-fold: (1) the overly forward/aggressive presentation of the upper-mids/lower-treble and (2) the narrow/compressed staging.

With regard to (1), I did most of my listening with the Atticus, which is already relaxed in the treble (though mid-forward). I found most modern music tracks (pop, rock, EDM, etc.) to be too strident and piercing in the upper-mid/lower-treble regions. This meant that oftentimes, for example, female vocals were uncomfortably right up in your face or shouting in your ears. It also meant giving the sound a kind of painful brightness that was completely unexpected/uncharacteristic of the usually toasty warm (if not dark) Atticus. (I suppose this could work better for classical or folk genres [not sure about jazz], but those are further afield from my preferred music.) Perhaps this was an issue of synergy with my headphones, or perhaps I'm simply very sensitive to these regions, but I just couldn't get on board with the way it diverged from my sound preferences.

With regard to (2), I found the staging to be narrow and cramped, if not claustrophobic. Instruments and vocals often competed for the same sonic space, and layering was not particularly strong. Perhaps this amp required a much longer burn-in time than I gave it, but I'm skeptical as to how much more the stage could open up from its baseline, and honestly, I wasn't that interested in finding out.

I found my Valhalla 2 (especially with the Tung-Sol 2C51 tubes) to be a much better match for the Atticus (as well as the HD650). I thought the Western Electric 396A tubes to work well for the HD650, which brought a nice warmth and increased resolution to the mid-range, but I found it to be too much (too forward) for the already mid-forward Atticus. The Tung-Sol 2C51s push the centered vocalist back a step (the slightest U-shape, at least compared to the WE 396As), which balances out the Atticus' frequency response and stage nicely. Going from the ZDT Jr. to the V2, the V2 might seem like it has a "veil" since the upper-mids/lower-treble are stepped back slightly, giving it a sense that vocals and upper-register instruments are overly smoothed and coming at you from behind a clear glass window. But I actually prefer this smoothness since it makes for a much more pleasant listening experience, though it can be said that the ZDT Jr. has a faster, more dynamic, "livelier" midrange overall. Finally, the more balanced/smoothed/warmed up presentation of the V2 also gives the bass more weight as well, at least relative to the ZDT Jr., which might have bass quality, but it was hard to evaluate more thoroughly since the upper registers overwhelmed it in quantity.

I also prefer the staging on V2: I hear significantly more space between instruments and between vocals, which makes for a much more enveloping soundscape and "realistic" (read: "live") presentation of the music. After hearing music presented like this, it's hard to go back to a narrower, more confined stage. In the end, the wider soundstage coupled with the mellower tonal balance is just so much more relaxing to listen to, whereas with the ZDT Jr., I felt like I was bracing myself the whole time I was listening to it.

All in all, it was an illuminating experience to hear the ZDT Jr., and I'm glad I was able to hear it, especially since I have limited exposure to high-end personal audio. I do hope Massdrop gets hum-gate solved, if only so that more people get a chance to hear this amp!

Just wanted to follow up on this and revise my earlier thoughts. After I wrote my post, and after reading so many positive reviews about this amp, it really bugged me that my impressions seemed to diverge so radically from everyone else's. I know everyone's hearing is supposed to be different, but I still think that we should still be able to establish some baseline experience, even subjectively, before we attribute any likes or dislikes to matters of taste. (After all, isn't that the whole point of reviews?) So when I got a chance to acquire this amp recently (one from the second batch, white dot, with the hum fix), I took it. I've been listening to this amp for the past several weeks now, and long story short: please disregard my original post (as quoted here).

I am 99% certain that the unit I had previously was defective (from the first batch), because the amp that I am listening to right now sounds nothing like it. I remember how disappointed I was the last time, as the amp just sounded...broken. Shrill and screechy, collapsed stage, no sense of warmth or euphony. And in writing up my previous comments, I tried to temper some of that disappointment by not letting it color my descriptions/impressions too explicitly, just in case that's really what it was "supposed" to sound like. This is all to say that my previous comments would have been even harsher than what they were.

But assuming that the one I have now is the real deal, I am very happy (and very relieved) to report that the ZDT Jr. is in fact everything I had wanted it to be, and I can vouch for all of the positive impressions posted here. THIS is the amp I should have had from the beginning. And I'd like to apologize if my impressions kept anyone from purchasing this amp when they wanted to, especially since the amp is no longer in production. Even though I'm taking back my previous comments, the one thing that you might take away from them is the possibility that there were (and still could be) defective units out there. The chances are small, and I'd be inclined to trust sellers, but I can only attribute the differences in my own experience to build issues and unit variances. (For example, I have not listened widely enough to other amps since then to be able to say that my hearing or my tastes have changed in any significant way.)

As for the sound, I don't have much more to add than what has already been shared. I will say, though, that between the Atticus, HD650, and HD800, I like it most with the HD800 and then the Atticus. It takes the thin-sounding HD800 and thickens up the sound, giving it a meaty fullness and making it feel as though the huge cavities in the earcups are now stuffed with glorious sound. It takes some of the harsh edge off the treble, pushes the midrange forward a bit with a smidge of that tube growl in the lower-mids and a subtle but noticeable sense of wetness/reverb, and adds a nice roundness to the mid-bass. The sub-bass is clearly rolled off, but I don't really find myself missing it (besides, I have other amps for that). Staging remains strong, especially in terms of the front-to-back and dimensionality.

All of these effects add to and enhance what the Atticus already does so well, making for an amazingly organic experience. The more laid-back Valhalla 2 (which I've since moved on from) seems soft and boring in comparison. Compared to the Lyr 3, the ZDT Jr. is more idiosyncratic and definitely has a bit more character: the Lyr 3 aspires more toward a certain kind of neutrality -- understandably, as a hybrid, it's more of a solid state sound with only the slightest hint of tube goodness.

With the HD650, the ZDT Jr. is almost too much of a good thing: while the tone is again rich and warm, it accentuates the vocal-forwardness of the HD650 a bit too much, but then again, the HD650 was never known as a particularly wide headphone. While I would be completely happy with this amp for the HD650, I think an OTL would suit it better, if that were your only pair of headphones. My Eddie Current Lunchbox OTL makes it sing: it widens the stage a bit more and adds extension at the extremes (low and high).

In any event, hope that clarifies things!

 

[PopZeus]

I finally swapped out a few components in my desktop rig, and managed to find a spot for the EC ZDT Jr because it just pairs great with the Aeolus. Love this amp! I can't believe how great Bossanova from the Pixies sounds with this rig. Tube amps were always such a hassle, I didn't want to bother with them. But my new desktop setup with the ZDT Jr feels the most like an endgame rig. Incredible!

 

[coletrain104]

Did Drop ever address this hum issue for owners of early models? I recently purchased one from another head-fier that was in the first batch. I didn't know such an issue existed, and no idea if it is present in the one I purchased (and am still waiting to arrive). If it hums is there some form of recourse?

 

[randytsuch]

I had a first batch drop unit with a small amount of hum that I sold. Before selling, I wrapped the transformers with magnetic shielding material, basically eliminated the hum.
I only heard hum with sensitive cans, normal cans were fine, but fixed it anyway. The shield material was given to me from someone from another forum, and he gave all he had away, so I don't have a source for what I used.

From what I remember, it was pretty easy to take the cover off of the power transformer, but more work to get the covers off of the little output transformers. You need to unscrew the board to get to all the screws for the output transformers.

If you had hum, I'd try adding shield to the power tx first, and see if that fixes it.

I also remember reading about someone who drilled a new hole and moved the power transformer away from the output tx's, and that fixed his hum. But I didn't want to drill into my amp so I didn't go there.

Randy

 

[coletrain104]

I had a first batch drop unit with a small amount of hum that I sold. Before selling, I wrapped the transformers with magnetic shielding material, basically eliminated the hum.
I only heard hum with sensitive cans, normal cans were fine, but fixed it anyway. The shield material was given to me from someone from another forum, and he gave all he had away, so I don't have a source for what I used.

From what I remember, it was pretty easy to take the cover off of the power transformer, but more work to get the covers off of the little output transformers. You need to unscrew the board to get to all the screws for the output transformers.

If you had hum, I'd try adding shield to the power tx first, and see if that fixes it.

I also remember reading about someone who drilled a new hole and moved the power transformer away from the output tx's, and that fixed his hum. But I didn't want to drill into my amp so I didn't go there.

Randy

Interesting, so did you wrap the outside of the amp where the transformer is visible, or did you open it up and wrap the actual transformer? Did you use a metallic sheet/film? I see there are a number of types of these materials.

Received it, and yeah, the hum is present on both of my Focals. Still sounds good with Elex, but with Elegia there is so little play with the volume that by the time it is loud enough, the pot is so low that the channels aren't even. I'm going to have to decide if it would be worth to fix the hum, given that I have to be so careful with volume on most of my dynamic headphones anyways.

Edit: Seems my unit is actually from a 'fixed' batch, though there is some hum. If it bugs me enough I may try to wrap the transformers. If anyone has any experience with doing this, or where someone else documented it, please let me know! On the volume note, I can get the results I want by adjusting the preamp of my DAC, I think this is just a case of high DAC output voltage, as this DAC (Geek Pulse XFi) is noticeably louder than my previous DAC.

 

[randytsuch]

Interesting, so did you wrap the outside of the amp where the transformer is visible, or did you open it up and wrap the actual transformer? Did you use a metallic sheet/film? I see there are a number of types of these materials.

Received it, and yeah, the hum is present on both of my Focals. Still sounds good with Elex, but with Elegia there is so little play with the volume that by the time it is loud enough, the pot is so low that the channels aren't even. I'm going to have to decide if it would be worth to fix the hum, given that I have to be so careful with volume on most of my dynamic headphones anyways.

Edit: Seems my unit is actually from a 'fixed' batch, though there is some hum. If it bugs me enough I may try to wrap the transformers. If anyone has any experience with doing this, or where someone else documented it, please let me know! On the volume note, I can get the results I want by adjusting the preamp of my DAC, I think this is just a case of high DAC output voltage, as this DAC (Geek Pulse XFi) is noticeably louder than my previous DAC.

You need to remove the transformer covers, and put the shield directly around each transformer.
I took some pics at the time, but have deleted them so have nothing to show you.

You need to remove the bottom cover to get at the screws that hold the covers in place.
I had a mistake in my previous post, the two smaller covers for the output transformers at the front are easier to remove.

To remove the bigger one for the power tx, you need to loosen one or more of the pots/switches on the front. I think one blocks a screw that holds the main board in place, and you need to unscrew the main board to move it out of the way enough to get to the cover screws.
You don't have to remove any wires, just gently move things around to get access.

There are lethal high voltages inside. I would unplug and leave for 30 mins before removing the bottom cover.
It would be best to check for high voltages with a meter before you do anything to the amp, but I don't remember where to measure now. Pretty sure the voltage will drop, but measuring is the safe way to do this.

Randy

 

[coletrain104]

You need to remove the transformer covers, and put the shield directly around each transformer.
I took some pics at the time, but have deleted them so have nothing to show you.

You need to remove the bottom cover to get at the screws that hold the covers in place.
I had a mistake in my previous post, the two smaller covers for the output transformers at the front are easier to remove.

To remove the bigger one for the power tx, you need to loosen one or more of the pots/switches on the front. I think one blocks a screw that holds the main board in place, and you need to unscrew the main board to move it out of the way enough to get to the cover screws.
You don't have to remove any wires, just gently move things around to get access.

There are lethal high voltages inside. I would unplug and leave for 30 mins before removing the bottom cover.
It would be best to check for high voltages with a meter before you do anything to the amp, but I don't remember where to measure now. Pretty sure the voltage will drop, but measuring is the safe way to do this.

Randy

Thanks Randy, reading up on the info provided by the seller as well. Actually doing so helped as it clicked to me that my studio monitors right next to the amp have powerful magnets in them. Moving the amp away from these greatly reduced hum, and I really have no issue where it is now, hardly audible in silence. If I do try to shield the output transformers, I'll be sure to give it plenty of time to discharge capacitors and such.

 

[DeweyCH]

FWIW Drop has some (one?) of these listed in their refurbished/B-stock page. Just go to their search function and input "refurb." It's $360.

 

[PopZeus]

Absolutely worth it imho.

 

[HiFiRobot]

Two of my favourite tube amps. Tube rolling is possible between the two

 

[blackdragon87]

Just was able to find one of these used. Looking forward to trying it with my zmfs

 

[kumar402]

Just was able to find one of these used. Looking forward to trying it with my zmfs

I have good memory of this amp and I would have never sold it but I had to travel. You will love ZMF out of it.

 

[JL3001]

Just was able to find one of these used. Looking forward to trying it with my zmfs

Really enjoying it with my Verite Closed.

 

[musicloverca]

I think the Eddie Current ZDT Jr is really good for the price! I enjoyed it more than a tube amp which cost twice as much (the Feliks Echo Mk II), and I like how it has a low impedance output too, many tube amps don't, especially the lower cost ones.

Drop briefly restocked this last year, but it sold out in an under an hour. Used is probably the only way to buy it.

 

[treys1]

Hey all, just grabbed one of these used and look forward to getting it!

I see people are rolling 5654s in the front, but all the links from this thread are dead to see what people are using in the rear. Anyone know?

Thanks!