GoVibe Porta Tube+ valve headphone amp/DAC in Review – beautiful in blue

There’s nothing wrong with cheap. I eat cheap. I wear cheap. I make cheap jokes. And for the longest time, Jaben shipped mainly cheap amps to my cohort: the masses, God bless ’em. But Jaben have gotten off that kick. They’ll ring the charity bells in another season. Today is the day of the Porta Tube+ valve headphone amp/DAC for your iPad/Mac, a delightful machine for bourgeois ears, and sound fit for a king.

The name of that kingdom? GoVibe.

24/96kHz upsampling DAC CIRRUS CS4398-CZZ (24/192kHz)
Vavle: 72 6N16B-Q
USB controller: Texas Instruments TIASIO20B
7-10 hours of battery life
Amazing sound

Typical of Jaben products, you have to poke around yourself where specs are concerned. You might find what you are looking for. You might not. There is NO documentation. You have no idea what DAC a Jaben product uses. Ditto the op-amps. Ditto the Porta Tube/+ valve. Ditto practically everything. It’s very much like buying a 1990 Hyundai car full of Yugo or Toyota parts – only the dealer knows. The good news is that the Porta Tube/+ packs a good bunch of parts that makThe other good news is that Jaben haven’t laid out a list of impossible spec. A lot of amp makers give spec that lists like 120dB dynamic range etc. Pooooooosh! No way. Won’t happen when supplying a signal, especially under load.

Before we get too far, remember Jaben’s Vestamp, also a GoVibe. GoVibe is Jaben’s hi end brand, and performance wise, it plays to that branding. There are lots of gotchas otherwise, but most are worth it in the end.

Build Quality
Once you’ve seen one aluminium amp you’ve seen them all. Jaben follow the crowd here. Yep, there are four screws on the front and on the back, and one buried in the volume pot. The logic board slides between two corrugated shelves and is piggybacked by a three-cell rechargeable battery.

The input and output ports are anchored strongly to the board and extrude their necks through three nicely sunk holes. The power switch is in good shape: stubby and metal and dressed in a shiny turtleneck.

A total of 28 breathing holes open to the world, half on top and half on bottom. As the insides get warm, these are absolutely necessary. That warmth is a few degrees above The National headphone amp. On a cold day, it’s a feeble heating brick. On a hot day, it’s feels like puberty all over again. At the very least, you know it’s working.

The Porta Tube’s one gotcha is its gain hardware, which is hidden behind those eight screws and a hundred or so cumulative twists. Adjusting it isn’t difficult. All you need is smooth tweezers or a small screwdriver to remove the jumpers to their adjacent slots. Each channel can be adjusted individually. Easy breezy beautiful. But, to get that far, you have break open the four screws on the front plate, then do the back, and nudge the logic board out. Hence the hundreds twists. Before you get far, a cop’s warning on the back may hinder your progress. “Warning: shock hazard do not open”, it says. Blink blink. Welcome back Jaben. How I’ve missed your pranks. If you’re a TMA reader, you may remember the Hippo box+ fake website prank. Or the prank of the funnilly backwards labelled bass and gain switches. Ah, Jaben, you certainly like a laugh.

Pop the jumpers into the forward position and you are in high gain mode

For some, it may not be funny. A few weekend warriors may abandon their screwdrivers at the back panel. Which is a shame. The Porta Tube and Tube+ have lots of power. Lots, especially, if you’re an IEM user, you’ll want to make sure that gain is set to low. The final problem is that the gain switches aren’t labelled. If you have a modicum of electronics wisdom, you can probably suss the gain by tracing the printed circuits. If not, I’ll tell you how it goes.

With both jumpers removed, the gain is high. With jumpers moved into the ‘forward’ position – that is: moved toward the front of the amp – the gain is set to high. All other positions are low. You can set gain independently for left or right. Works great if one ear is better than another. Aside from the rear cover prank, there’s no reason to take out frustrations on the Porta Tube. In all other realities, it is a wonderful amp, wonderful, and deserves its lime light.

How’s the volume pot work? you may ask. Wonderfully. It is silky smooth and easy to grab. The volume notch is perfect for indicating where things are, even in the dark.

Ergonomics and Polish
I’m not sure TMA’s pictures do justice to the Porta Tube+. It is beautiful. The blue chosen for casing is brilliant against the silver trim and the blue LED looks like such a match as you’d not see this side of a gin and tonic. The LED isn’t too bright, but late at night in your dark room, you may want to cover the front of the Porta Tube+ with tape, or a bad myster novel, or something.

Here's the box that this 700$ piece of audio equipment comes in

In many ways, beauty is skin deep. I’m looking for a 700$ product that screams 700$. I’m looking for engraving, or a nice font, or countersunk bolt ports, for hardened steel screws. I don’t want to see the fingerprints of factory workers on the logic board or scuff marks on the face plate. I don’t want to see a warning not to open the back plate when opening it is the only way to access the gain switches. Those are part and parcel of the GoVibe Porta Tube+ experience. You have to decide whether or not it is worth it to you.

But with the ticks and tacks, come some plusses, too. Again, the volume pot is perfectly smooth. The in and out ports are spaced wonderfully for oversized headphone jacks and interconnects. Another plus is the addition of two headphone outports. They come in parallel, so you can use the Porta Tube evenly with two of the same headphone with no volume discrepancies. You won’t phase the Porta Tube or Porta Tube+. Its innards may not have the last word to say on polish, but holistically, the Porta Tube+ is eloquent.

You’ve got 7-10 hours of battery life, parallel 6,3 and 3,5 mm jacks, internal charging, and a hidden gain switch at your disposal. The Porta Tube and Porta Tube+ do what they should and don’t disappoint. The 700$ you lay down for the Porta tube buys you a workhorse. As long as you don’t need balanced output, or need an electrostatic amp, the Porta Tube and Porta Tube+ are absolutely made for your headphones, no matter the sensitivity, no matter the Ω.

The + version sports a USB DAC that upsamples to 192kHz from its native 24/96. If you listen to music from your computer, this is a killer feature. It bests The National for the simple reason that there is less noise at all points on the volume pot, and it has more voltage than the VestAmp+ going into the output ports to keep your headphones from distorting even at ear-killing volumes. Be forewarned and be careful: the Porta Tube is loud.

Sound quality
The first time I heard the Porta Tube, I was in a curry restaurant in Shinjuku. I had my trusty Sleek Audio CT7 in my ears and disbelief written on my brows. I approached the 3,5mm jack with a hand that had plugged hundreds of headphones into dozens of amps. Years ago, I would have shook with eagerness. That day, however, was just another day, another amp. I approached the Tube+ as I do every other amp: and test first for background noise. My fingers sunk the headphone jack in and made sure the volume all the way down. They flipped the power switch on. No noise. They raised the volume to what I assumed would be a comfortable listening level. No noise. They mashed the volume pot to the end. Noise finally piddled out, but so barely, I assumed it was the curry.

That was January.

Nearly five months later, with a unit from Jaben on my desk, and with my windows shut, I am even more impressed. The Porta Tube+ is almost as noiseless as an amp of its output power gets. The difference between noise at the zero position and noise at the 100% position is tiny. In fact, at 100%, the Porta Tube+ outputs less noise than The National does at about 25%. Impressive indeed.

There are many IEM oriented amps that exhibit less noise than the Porta Tube+, but few can also serve distortion free signal at ear-splitting volumes to headphones such as the DT880 600Ω.

The importance here can’t be glossed over. IEM users have a hard time. With the exception of the polishes turds made by HiSound, and a many would-be respectable Walkman units from Sony’s lineup, all portable MP3 players will have less noise in their signal pathways than portable amps meant to upgrade the sound. The Porta Tube+ is no different in a general sense, but specifically, its noise at highest volume settings is astoundingly low. Which, despite its insane power, is the most important reason I can recommend it even for IEM users.

Here in Japan, quite a few crazy audiophiles plug the Porta Tube+ into their stack, which is a combination of several audio bricks such as the Cypher Labs AlgoRhythm Solo or Fostex HP-P1, an external DAC, amp, and maybe even a signal splitter.

Noise isn’t the end of the story, however. Extension is the other, and presentation. The Porta Tube series has wonderful, bright, full-bodied mids and highs. It is one of the best, most articulate amps I’ve heard in any format. When I say bright, I don’t mean grating, or sibilant. I mean clear as a bell, and highly resolved. Instrument separation is good, especially in mid and high frequencies, but better situated to play back small band recordings than symphonies. You can pick instrument from instrument no matter the headphone, but there is a bit of decay in the mid range and low frequencies. That decay, coupled with typical valve-induced distortion, warms up the signal.

On one hand, I’d describe the GoVibe as energetic and bright, and on the other, I’d call it intimate. It’s an interesting blend of two very musical properties that makes the GoVibe Porta Tube intoxicating.

Regarding brightness, perhaps it is best described as an articulate high frequency even in the face of warm valve distortion. No matter the earphone, no matter the headphone that I plug into it, what greets me back is beautiful. I think by now it should be obvious that I dislike signals that curtail high frequencies. I’m very particular about my highs. The Porta Tube+ one of a few special amps that drives perfect transition from mids to highs. The lay and play of cymbals to percussion in Massive Attack’s I Spy, is delicate and real. Imaging is precise, but directed from front of the head, wrapping slowly around, and back, but not too far. The end result is one of sitting in front of two well-placed speakers in a medium sized room. Focus is definitely at the drivers, but nuances from the walls and furniture sneak in relaxingly and naturally.

Again, I think that typical valve-type harmonic distortion, and a centrally concentrated bass output are the happy culprits. The end result is utterly smooth, slightly warm, but wonderfully extended output. Grado users, there is enough low Ω power to drive your phones perfectly, and in your quest for on-stage performance, the Porta Tube is probably a perfect guide. Users like me who love the wide, expressive DT880 headphone are in for another treat. The sometimes tweaky highs of said headphone are tame, lusher than they are through another amp, or from a stereo system. Fortunately, the Porta Tube+ isn’t too tubey.

The Wood Audio WA3+ is about the most tubey headphone amp I’ve heard in my 20 years as a silly audiophile. Its intimacy is wonderful, but comes at a price: I’d not use it with half the headphones I own. The Porta Tube is different completely, but retains the warmth of a good valve amp.

Let’s get back to the music. Protection’s title song, Protection, fronts mid-bass heavy lines, simple machine drums and almost comatose female vocals. The following tracks step in similarly but add male vocals, and even deeper basslines. Slow, full-bodies female vocals, the likes which jazz and massive attack produce, are absolutely magical. Is it the aforementioned decay? If it is, the explanation is too simplistic. Whatever the fact, DT880 and Porta Tube, or CK10 and Porta Tube, even the K701 and Porta Tube bring out all the lustre that’s there somewhere, in the recording.

The above are headphones with some high end bite. Middle-voiced headphones such as the Sennheiser HD650, HD600, Fischer Audio FA-002W are what I would consider second-tier combination phones for the Porta Tube. Keep in mind that the Porta Tube has no lack of detail in the high frequencies. But, it is slightly warmer than the typical solid state amplifier, be that distortion, or decay, I’ve no firm answer. It pairs well with the above headphones, but will emphasise some of their dark, nurturing characteristics.

An amp this intoxicating deserves a good audition with your favourite headphones. Spend a few minutes, or a few hours, and you’ll probably walk away with a new blue pretty under your arm and a significantly lighter wallet. It’s worth the price.

Charts Disclaimer
This review’s RMAA measurements reflect the performance differences between the Porta Tube+ fed by the iPod touch and driving a Beyerdynamic DT880 and Earsonics SM2. Since these measurements are taken with my equipment, they should not directly be compared measurement-to-measurement to other technical data taken with different equipment. The data represent the ability of the amplification circuit to drive headphones and speakers.

Frequency Response
The Porta Tube/+ has no problem delivering high levels of  resolution to any headphone. Even the SM2, which concoct all sorts of distortion for lesser amps, do nothing to phase the Porta Tube. You will notice, that there is small fall off in the low and high frequencies both. That is part of the original signal, and not load effect. Small levels such as exhibited by the Porta Tube (~1,5 dB) are probably not audible unless you are a dog.

Loaded noise and dynamic range
The Porta Tube+ manages 90,5 dB of dynamic range, 6dB less than CD quality. It also manages -90,5 dB of noise, making it a very clean source, but not quite up to CD quality. Then again, this amp is a valve amp. Part of it s allure is its atypical distortion and noise images.

Here’s one of the reasons to get a valve amp. For your money, you get stable, comforting distortion that varies little from source to source. That distortion is often called warm, or comforting. I can agree with both adjectives, but not in the same way I agreed with them for the Woo Audio 3. The GoVibe Porta tube is a more solid, typical sounding amp than the WA3. Distortion is much less for input and output, but still, there is ring, and lovely smear here and there. Both IMD and THD measure high, as they should from valves.

The Porta Tube+ follows the same rule that the VestAmp+ does: USB input will have the lowest signal gain. Line input from portable sources will be more powerful than USB. Home sources, or excellent portable sources such as the AlgoRhythm Solo will be loudest and clearest, driving the Porta Tube+ as well as can be.

This amp scales up very well. Strong sources and low gain induce very little phase error in phones like the DT880 600Ω. High gain introduces more, but those phase errors are coming at extremely high and dangerous volumes, volumes that no one should ever listen to. Suffice it to say that the Porta Tube has gobs of power. Like the ALO National, it is ready to replace many a home amp with no problem.

As a DAC
I’m not a big fan of USB-only DAC’s though they seem to be en vogue in the last few years. One of the reasons is that the implementation of USB DAC units aren’t as good as their line-in counterparts. Indeed, the Porta Tube+ performs best via line in, sporting better stereo separation, a lower noise floor, and better dynamic range.

But, it works wonderfully with a computer, too. I’ve not noticed any nasty USB noise in the signal, and the Porta Tube+ is fully plug-and-play, immediately recognised by my MacBook Pro. The output is considerably lower in USB mode than when driven from home-level sources, which is good news for IEM users. And, despite the output is lower, there is plenty of volume for every headphone I’ve plugged into it.

An interesting thing is that the USB input and the line input work simultaneously, meaning a running line in and music playing via USB will run through the headphone output of the Porta Tube+ concurrently. Remember to keep your different sources unplugged when you want to listen to either USB or line in.

Using with iPad
Use of the Porta Tube+ as a USB DAC for the iPad can be done, but it isn’t see-through easy. The iPad’s USB output doesn’t have the voltage to run the DAC unit in the Porta Tube+, which isn’t run on battery power. To run the DAC, you will have to use the included mains adapter and plug the iPad into the camera connection kit, and the Porta Tube+ into that. It works immediately and sounds as good as as always. It just isn’t portable.

Considering that the Porta Tube+ is a desktop/home worthy unit, there is no problem. But, users who want the cleanliness of pure battery driven signals won’t get it with the iPad. Netbooks, on the other hand, can make use of the Porta Tube+ DAC without the mains.

Use as a portable amp
Let’s face it, the Porta Tube/+ is an amp that tips the scales heavily. It is large, hot, and relatively weighty. Still, there are cargo jeans, and amp bags, and slings. The fact that it carries a battery that is good for 7-10 hours means that you can have most of a day’s work and commute buttoned up by one device. And since there is comparatively very little background noise and the volume pot is well balanced, it works wonders for sensitive earphones.

In fact, whilst driving the SM2, there is no more distortion or IMD than there is whilst driving the DT880. The signal sounds the same no matter what is plugged in. This is very seldom achieved by any amplifier. You could say the Porta Tube+ has no preferences of output earphones. Quite a feat.

For portable audio, I can’t recommend the Porta Tube enough for those willing to tote the extra weight.

Despite staunch competition from ALO and Vorzüge, the Porta Tube+ is my favorite sounding portable amp. Its lively, intimate sound is perfect for most headphones, and when paired with bright, detail-oriented headphones, it calmly takes control. Jaben won’t win any unboxing video championship, but that is obviously not their goal. With singular purpose, they have created a truly world-class headphone amp/DAC that I expect will wow discerning audiophiles the world over.


App Summary
Title: GoVibe Porta Tube+ headphone amplifier/USB DAC Developer: Jaben
Reviewed Ver: Porta Tube + Min OS Req: 4.3
Price: Porta Tube: 650$

Porta Tube+ 750$  

  • extremely powerful output
  • wonderfully detailed, warm sound
  • No preferences for earphones
  • Beautiful colours
  • Scales well with better equipment
  • Half arsed workmanship
  • cop warnings
  • No spec, accessories, literature



Hot damn! Headphones really are a rockin’ way to enjoy music, right? Feel free to explore TMA’s headphone oubliette

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