ZMF Pendant - Tube Headphone Amplifier - Official Thread

While most headphone enthusiasts are aware of Zach Mehrbach’s excellent ZMF Headphones, they also offer a pure tube headphone amplifier, the “Pendant”, with enough power and flexibility to drive pretty much any high-end headphone.

The name of the amp, per the ZMF site, derives from:

Pendant: an artistic and musical component intended to match and complement. The ZMF Pendant perfectly matches any ZMF Headphone or other musical device that can be worn on the head.

The amplifier was designed in collaboration with ampsandsound, with the goal of delivering an amplifier that both perfectly matches any ZMF headphone but that can also be used with any other headphone you might consider.

It’s offered in a standard black finish, or with optional custom wood bases (as one might expect given ZMF’s legacy of gorgeously finished wooden-cupped headphones), as well as options for a standard, or hand-selected “vintage” tube set.

Specifications
  • Single Ended Ultra Linear tube amp

  • 8 ohm (low-z) and 300 ohm (high-z) outputs

  • Dual RCA inputs

  • Pre-amp outs via RCA

  • EL 84/6BQ5 Driver tubes, 12ax7, 12at7, and 12au7 input tube options, EL 81/6CA4 Rectifier

  • Transformer based design

  • 3 Watts @ 8 ohms and 2.5 watts at 300 ohms

  • ALPS volume pot

This is the spot to discuss this sonically and visually beguiling amplifier as well as tube complements/rolling options for it …

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This belongs here…

Been really loving this amp! To me it has a similar sound profile (tubes depending) as my Cayin Ha-1a MKii but with a little more depth and quality to the sound. Also it aesthetically fits with my audio shelf, and I really like it :stuck_out_tongue_closed_eyes:

To me it has more of that “neutral warmth” tube sound…not overly romantic and lush but more like a warm blanket lol. Very enjoyable experience, I did a little tube rolling and it does allow for some dialing in to your preferred sound profile. But, I’m not experienced enough with tubes to know which I prefer and usually just stick with recommended ones. If I have a bunch to experiment with, I’ll roll until I hit what I like ha!

Setup is super easy, and the sound to me is very Goldilocks in that it is just right! If this would be your first foray into tubes then be prepared to be “wow’d” but if seasoned in the way of tubes it will be what you would expect and be plenty happy!

(PSA: for awareness I’m a bit of a ZMF fanboy ha, my current top 3 headphones 2 of which are ZMF the other I don’t really consider to be a headphone :face_with_monocle:)

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Looks amazing with the headphones next to it.

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I am currently saving up for this amp, and plan to pull the trigger next month. I have a few other amps, I am looking at, but the Pendant is at the top of my list. I plan to use it with my Aeolus and Ori, and have a bunch of 12au7 tubes, ready to go. Still trying to decide on the black base or a custom like the one in @DarthPool picture. This is going to be my endgame amp.

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@DarthPool was kind enough to drop off the Pendant for me to evaluate, and I have to say this is a ton of fun. Switching back and forth between this and the SPL Phonitor X actually makes me think I prefer my Verite with the Pendant - enough where I’m now thinking “damnit, now I need to go down this tube rabbit hole again”. I’ve traditionally been more of a high end SS kind of guy. The main difference I hear is an increased sense of stage, along with slightly more emphasized ‘texture’ to the sides - which admittedly I don’t properly understand at the moment. Basically, the Verite on the SPL Phonitor X is more focused, and on the Pendant is a more ‘pulled apart’ experience. Comparing it with the iFi Pro iCAN, the SS option is much more focused in front of me, with an even flatter presentation. That’s where I hear the biggest difference. I was actually surprised at how tight and well-controlled this sounds on the Pendant. Normally I expect that from high performance solid state options like the Cayin IHA-6 (and the SPL Phonitor X), so it’s nice to see the Pendant can keep up. But once again the biggest difference is in the sense of stage and image structure (texture?).

One thing to note, don’t have it near other electronic devices, because you’ll likely get a bit of interference burble. This has so far been far less noticeable with the JJ Electronic tubes, but it’s still there occasionally (and I don’t fully understand why, maybe @Torq can explain why this effect varies?).

In any case, I’ll aim to do a full review of this soon.

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This is a relatively common thing with small signal-tubes and, to a certain extent, smaller tubes in general - especially when the tubes are in the open (i.e. unshielded).

Assuming what you’re hearing is down to radiated/airborne EMI/RFI:

It is usually simply down to the fact that different tube designs, even among compatible tubes, exhibit slightly different electrical properties. These can be down to the actual design/implementation, or just variations in assembly - which is why you sometimes get this even with the different copies of the same tube, from the same manufacturer, from the same batch.

So if you get two tubes that exhibit slightly different gain, especially in an input or signal stage, you can find that one will be sensitive enough to have issues in one environment where another tube exhibits nothing.

The metal filaments in the tube all act like small antenna. An antenna’s performance is dependent on many things, but at its most basic level its a function of its physical relationship to the wavelength of a signal. So small changes in length of a filament change the “tuning” of its “antenna” behavior and thus also its sensitivity to a given signal.

Finally, variations in the amount, and distribution, of “getter” material within the tube after it is flashed. The purpose of the “getter” is to harden/maintain the vacuum after evacuating and sealing the tube, and to absorb any gaseous molecules that were not pumped out (initially, and as a result of off-gassing from the metals in the tube during use). But it can wind up acting as a (very) limited (reflective) shield of sorts - and since the distribution isn’t 100% uniform between individual tubes, you can get variable effects there.

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I am very much looking forward to any review of the Pendant as I am also considering it, along with two others, as an end game amp with an Auteur as my main can. Very hard to find much information on this one but opinions seem to place it as controlled, neutralish, having a low noise floor (outside of external interference) and with some speed. Also able to kick when it needs but not for bassheads or those who want real slam.

I am quite curious as to the soundstage and imaging on the Pendant: is there depth, is it holographic, is there precision, coherence (not blobbed up)… ?

Will this be on the Headphone Show?

Resolve, IIRC from your Youtube channel, you have both the Verite and the Auteur in your stable so I imagine you will be using those extensively for your review?

Off Topic: Resolve’s extended Youtube review of the Auteur was very helpful when deciding to make my own purchase, so much thanks to him.

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I think it covers all your requirements… it is rather nice! So far one of the best tube amps I’ve heard! I’ll let @Resolve and @Torq put their more technical eye on it as far as a response. But, from my perspective as just a listener, it has plenty of authority where appropriate, excellent staging and imaging, with a more neutral tube sound. To me it flirts the line of Solid state amps and OTL tube amps. The only other amp I’ve enjoyed that is similar is the Cayin Ha-1amkii, which I own and think is almost as good as the Pendant but lacking some of the stage, imaging and some of the authority in the low end, while leaning even more neutral.

Also, keep in mind tubes will play into the sound a lot so tube rolling to find your preferred sound profile…

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That goes with what I managed to gather so far: SS characteristics with a tube flavour.

Of the 3 amps I am considering, I currently have the Pendant as maybe a #2 choice (or 1b choice) and have asked Zach a few questions about it. Ive been scouring the online forums looking for as much info as I can find as I want to make sure I am as informed as possible. I mostly do acoustic/classical for my dedicated (audiophile?) listening but will listen to everything including jazz, pop, metal, etc., as long as it’s well recorded and hasn’t had the dynamics compressed out of it.

Of the three, it seems like the Pendant is the least reviewed so finding this thread is a potentially nice find that will hopefully provide some extra information to guide my decision. All 3 amps come from very well regarded people in the audiophile community so I would probably be happy with any of them, still would prefer the one that would make me the most happy though, good luck to me!! :wink:

Very much looking forward to these reviews.

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The one thing I keep hearing is that it seems like no one has really done some serious tube rolling with the Pendant, and I am really looking forward to trying all my different “holy grail” tubes when I buy mine. I know some have rolled a few different tubes, but it seems not to the extent I plan to roll. This amp can take 12au7, 12ax7, or 12at7 for the driver tube, there are quite few different sounding tubes within those types. I have a bunch of different 12au7 I plan to roll, as well as the EL84 power tubes, so I am stoked to see what rolling can really do. Don’t get me wrong, I look forward to hearing the reviews with stock tubes and what ever the vintage set most are rolling, but I really want to hear how it responds to some serious tube rolling, and can’t wait to get my hands on one. I am almost there funds wise.

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I’d be interested in how sensitive it is to tube changes. If the sound differences are very slight I will probably just stick with stock tubes if I were to purchase. On a positive note, the tubes it uses are relatively inexpensive in comparison to some - talking new production, not vintage or NOS, and are easy to find.

Just knowing how different some of my NOS 12au7 sound from each other, I am betting the sound can be tweaked enough to justify rolling some NOS tubes, but will shall see. I have noticed what some of the tubes being used in the reviews are, and I know there are some tubes that have quite a different sound sig. than those. Of course this is not going to be a “tube rollers paradise” like a Glenn OTL, but I am betting rolling is worth it on the Pendant too.

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I don’t have the list to hand, but the demo Pendant model that Zach sent out included 3 sets of power tubes, 4 different signal tubes and 3 different rectifiers.

I did some rolling with those, which will be covered in my review, but I didn’t do exhaustive combinations (as that’d be 36 combinations).

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Awesome! I am looking forward to hearing what tubes were used.

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So I’ve been evaluating the Pendant for just over a week now and I’d like to give my thoughts on it. To begin with, I’m not traditionally a tubes guy. Maybe initially when I first started out I thought having a tube amplifier would make things sound more ‘musical’, but that eventually gave way to chasing ‘transparency’ and perfect measurements. But more recently, over the past several years, I’ve come to the conclusion that this is the wrong approach.

When you get into this hobby and research enough to convince yourself you’ve transcended what you might assume is the snake oil or audiophile nonsense that props up tube amplifiers, I think it’s all too common to overvalue certain publications and measurements that lead to this view. We’ll latch on to data points, even if they don’t provide a complete picture of what the experience will ultimately end up being. It’s like saying “here’s what’s important, because this is what we can measure”, and in my mind there’s simply more to the story when it comes to our experiences. There are a few reasons for my about-face on the question of tube amplifiers, but in my mind, experiencing the ZMF Pendant with the ZMF Verite is a prime example.

To begin with, the Pendant is touted as a flexible amp that can be used for a wide variety of headphones. I’m super skeptical about this claim, because its two outputs have 8 and 300 ohms output Z respectively. To me, this sounds crazy, especially given what I look for in solid state amplifiers, where you don’t want to alter the FR and risk introducing distortion. But then I’m reminded that this is a tube amplifier, and that’s exactly the point. It’s changing the sound in some fashion.

To be more specific, with the ZMF Verite, the high Z output elevates the bass slightly. I was able to demonstrate this with some measurements as well. I assume this would have a more significant effect on lower impedance headphones - remember that the Verite is a 300 ohm headphone. In any case, this explains why some people have reported the high Z output to have better ‘slam’, it certainly imparts that perception, but it’s likely just due to the changes to the frequency response.

The low Z output didn’t change the FR in any way, however, and so when the Pendant is described as ‘neutral’, I think they’re right. There was no measured difference between the Verite on the Pendant (low Z out) and the Verite on the SPL Phonitor X. But here again is where we need to not latch on to incomplete data points as strongly, because the experience of listening to the Verite on the Pendant is dramatically different from the Phonitor X - and on the whole, a lot more interesting.

To describe the sound, it’s as if everything is now much more holographic, with increased depth. Image distinction and structure is also enhanced, to the point where certain sounds pop out at me and actively surprise me. This is most noticeable on far left and far right. To put it another way, it’s as if the deepest part of the Verite’s depth extension is enhanced and more well-defined than what I was used to. The Pendant is also surprisingly quick, everything sounds tight and snappy, at least equal to the presentation on the Phonitor X. Needless to say, I’m fascinated by this combination, and now I need to potentially go down the tube rabbit hole and find more interesting system combinations.

Now to some of the bad stuff. While this is supposed to be a versatile amp for a wide range of different headphones, I found that I didn’t really like it as much for some of them. Planars in particular were not a good fit to my ear (at least the ones I had here). It sounded as if the treble was being ‘flattened’ to some extent, and I’m not entirely sure why that is. It might also just be that I haven’t found the right tube combination to make that work, but at the moment I’m left feeling that it might be versatile in the strict sense of “it can power a wide variety of headphones”, but not necessarily versatile in the sense that “it makes them all sound amazing”. The other dynamic driver headphones I tried it with sounded better, but still not on the same level as with the SPL Phonitor X, or even my Cayin IHA-6. Interestingly, the Focal Elegia didn’t change for the better, but the Sennheiser HD820 did. This makes me think that the ideal use for the Pendant is with high impedance dynamic driver headphones, even if it can power everything else just fine (or I need to be more specific with tube combinations for those other headphones). With ZMF headphones though, I think it would probably be exactly the right pairing.

So with that said, for anyone who owns a ZMF headphone, seriously consider the Pendant as an excellent companion amplifier. I’m not willing to say it’s the absolute best, because I haven’t heard what some others have recommended like the Glenn OTL, but those are also hard to come by at the moment. In any case, for increased depth, nuance, and sense of realism, the ZMF Pendant provides an experience that perfectly demonstrates why it’s probably not worth caring too much about measurements that fight the imperceptible difference wars. It’s the experience that matters, and this is a very good one.

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Thanks for the info! I would love to know what tube combos you have tried.

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For this one, Zach included a number of vintage tubes, which I’ve been playing around with. I’m currently using it with the RCA 6211. They all sound unique, but as Zach mentioned, the input tubes make the most difference. I find that with the vintage tubes, there’s a bit more ‘tube noise’ than with the JJ set, which has so far been my favorite - only for that reason though. You do also need to have the unit on for a bit for the ‘pops’ to disappear, so it’s not exactly easy to compare tube tonal differences. But that also means that the differences are substantial enough that they leave a lasting impression when swapping between them.

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It is fun to read someone really experience a good tube amp, especially if they are new to them. The holographic nature is exactly what I like about it.

Just because they have tubes doesn’t mean they are going to be warm and gooey sounding either, although some are (BHC, Mogwai w/ icky tubes, Elise, etc).

Planar headphones generally won’t jive well with tube amps, unless they are hybrid designs. For those I recommend the Lyr 3 and liquid platinum. Hybrids generally won’t give you the real tube experience though, more of a compromise between SS and tube.

Next thing you know, you’ll be building a BH Crackatowa. I think you’d like it.

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I have yet to hear the Pendant or ANY tube amp for that matter. But I just wanted to say this line is beautifully written. This sentiment has taken over a lot of industries for a long time (e.g. healthcare industry’s blind eye towards mental / emotional contributions to health because they’re difficult to measure and prove in a lab environment).

Reading this forum over the past few months, I have opened up to the fact that subjective experience is nuanced and extremely difficult to measure. Just because something doesn’t measure highly in limited metrics doesn’t mean it’s not enjoyable.

I’m looking forward to your full review.

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Hi Andrew, @Resolve,

Welcome to the “Wonderful World of Tubes”!!!

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