Pros - Portability, battery charging on the go, plenty of power for IEM's and portable Headphones
Cons - You can't use a protective case for the iPhone, leaving it exposed.
iPhone 3G/3GS owners, meet the GO-DAP
A while back I stumbled across an introductory post in the Sponsor Announcements and Deals Forum on head-fi.org for the new GO-DAP portable headphone amplifier for the Apple iPhone 3G/3GS from VentureCraft. As an owner of an Apple iPhone 3G, I was intrigued by what I read. The GO-DAP was designed as an all in one solution for the active audiophile iPhone 3G/3GS owner. It's a portable amplifier first and foremost, but it also offers the convenience of a built in Line Out Dock and offers a rechargeable battery. Now, we all know that rechargeable batteries aren't new in portable amplifiers, but the ability to charge your iPhone on the go is a welcome new feature. The battery in the GO-DAP effectively doubles the battery life of your iPhone. I noticed in the announcement that VentureCraft was looking for User reviewers. That was enticing enough for me to contact Hana Takano, the Global Distribution Manager, to offer my humble services. Thankfully, as an early applicant, I was accepted as a reviewer.
In our initial discussions, Hana was very forthcoming about the design ideas behind the GO-DAP. VentureCraft's goal was not to produce a mainstream flavored amplifier. By that I mean, they weren't interested in boosting the bottom end (bass) for the mainstream listener. Their main focus was on a more accurate amplifier that catered more to the Jazz listener, more specifically, they had female Jazz singers in mind. As a fan of jazz music and female artists such as Sophie Milman, Melody Gardot and Diana Krall, I couldn't wait to hear what the GO-DAP had to offer. A few days letter my test unit arrived from Japan.
Before I get further in, let's get some trivial matters out of the way. For my testing and comparisons I mainly used a playlist consisting of songs from the following artists and albums:
My one and only thrill
all mp3's ripped at 320kbps with Lame3.98r
From this moment on
all mp3's ripped at 320kbps with Lame3.98r
Take Love easy and Sophie Milman
all mp3's ripped at 320kbps with Lame3.96
The primary headphones and earphones used during my evaluation:
Shure SRH840 (840)
Westone 3 (W3), equipped with Shure Olive tips.
For amplifier comparison, I used my iBasso D4 Mamba with my Qables Silvercab – Pro Line Out Dock. I also compared the performance of the GO-DAP to the Headphone Out of the iPhone 3G.
Now that that's out of the way lets get to the specifications of the unit itself.
Output Power:300mW (16Ω) Signal to Noise Ratio:>= 95 dB (A Weight) Distortion:z<0.009% (10 mW) Frequency Response:10 Hz - 120 kHz Suitable Headphone Impedance:16Ω to 100Ω Power Supply:Built-in 1450mAh/Rechargeable Battery Op-Amp: OPA2134U (Texas Instruments/Burr-Brown) Pre-Amp:OPA2338UA (Texas Instruments) Power-Amp:TPA6130A (Texas Instruments) Size:W 65mm x H 132mm (including knob) x D 23mm
That should be enough data for those interested in the numbers.
I chose my favorite and most familiar In Ear Monitors and the only Headphones I owned at the time for my review. The Westone 3's are extremely efficient with a low impedance of 30 ohms and my Shure SRH840's are rated at 44 ohms. Both well within the range of the GO-DAP. The GO-DAP is capable of driving them both to unhealthy listening levels with ease and without clipping or distortion of any kind.
Let's get back to the reason you're reading this, the GO-DAP. The packaging is simple yet effective and very eye-catching (loud, flashy). The package gives off a 1970's disco vibe with it's bright colors and illustrations. The package is made from a sturdy paper product and is recyclable.
You'll be pleased to know that no sharp objects are required to remove the GO-DAP from it's secure resting place. The plastic cradle is held together by four depressed buttons on the corners and it doesn't require any great feat of strength or tools to pop them apart. At the top of the insert, you'll find the USB cable (USB 2.0). Unfortunately, the included USB cable is rather short in length (13 inches/33 cm). That forced me to place the GO-DAP on top of my PC's tower when charging was needed. If you have a USB hub on your desk, it won't be an issue. The cable utilizes a standard USB Type A connector on one side and a Mini-A on the opposite end, so finding a longer cable should be easy and inexpensive, should you choose to go that route.
Charging the GO-DAP takes approximately 5 hours when it's completely discharged, and the Lithium ion battery should cycle approximately 500 times during it's lifetime (per manufacturer).
Now, you may recall that I mentioned earlier that the GO-DAP is capable of recharging the iPhone with it's integrated battery, well that's true. The 1450 mAh battery bests the 1200 mAh battery in the iPhone and effectively doubles the time between charges. Of course, your mileage may vary.
Pairing the iPhone with the GO-DAP is very straight forward. Slide the iPhone down the guide rails and seat it onto the dock and your set. The connection is secure and stable.
Unfortunately, you'll notice that the design does not allow for a protective case for the iPhone itself and the screen and edges of the iPhone are exposed. If you are fumble fingered, clumsy or accident prone I suggest a small camera case be used to transport the combo. For those who are used to carrying an iPhone with a portable amplifier, you'll find the GO-DAP very convenient. Never again will you be forced to use a rubber band or velcro to keep your units together. You also won't need a Line Out Dock (LOD) or mini to mini cable, saving a bit of space. The units paired measure 1 ¼ inches thick (3.2 cm) at the widest point. As advertised, the unit acts as a stand when placed on it's side allowing you to view videos and movies hands-free.
The GO-DAP is a user friendly gadget, it has a small flush set button on the lower back side to check the battery life. On top you'll find a 3.5 mm headphone out, a volume knob and a small, red led lit, 3-way selector switch, that's it.
That switch determines what happens with the GO-DAP/iPhone combo at all times. The selector switch offers 3 positions: OFF, CHG > I and SYNC. It's easy to determine what's happening when the unit is on it's own (disconnected from the USB cable). Off is self explanatory, the iPhone works normally and the GO-DAP amplifier is off. In order to use your earphones or headphones while the switch is in the off position, you need to plug them into your iPhone. When you select the middle position CHG > i, the GO-DAP will charge your iPhone and allow you to use the GO-DAP headphone out. When the switch is set to SYNC the GO-DAP amplifier is powered exclusively, giving you hours of listening pleasure. I have a confession to make. I haven't done any measured time tests on the battery life as of this time. But, I have listened for four nights straight since charging the battery and I've averaged 2 to 3 hours per night. VentureCraft claims that the iPhone/GO-DAP combo will allow you to “talk” for 12 hours straight, I'll take their word on that. I won't be confirming that anytime soon. As for listening, I believe the GO-DAP will give you well over 10 hours of amplified listening at average listening levels. I'll try to follow up my review with more accurate test figures. This review is focused on the functionality and sonic virtues of the GO-DAP.
Now, when you plug the combo into a standard USB source the switch functions a little differently. With the switch set to the OFF position, the GO-DAP charges, with or without your iPhone attached. The CHG > I position has a few functions. With the iPhone connected to the GO-DAP and the switch set to CHG > I the GO-DAP is charged and allows use of the amplifier. If the iPhone isn't present the GO-DAP is charged. In the SYNC position, the iPhone is charged and you can synchronize with iTunes. You can also use the amplifier in this position as well. Make sense? If you have any questions feel free to send me a message and I'll try to clarify.
Amplifier sound quality:
The sound, isn't that what it's all about? Well, as suggested by Hana, I assembled a playlist of a few of my favorite female jazz singers and set myself up to analyze the GO-DAP's sound. The first time through the playlist I listened straight out of the iPhone headphone out for a base line sound. The second time through I listened through the GO-DAP. The third time I did extensive A/B testing, switching from the headphone out of the iPhone to the GO-DAP, sometimes mid song. The fourth time through I compared the iPhone/GO-DAP combo to my iBasso D4 DAC/Amp (fed the same MP3's via my Qables LOD and iPhone). Finally, the last listening session was a sampling of some of my favorite songs in other genres through the GO-DAP only. In order to condense this review, I'll be highlighting certain aspects and focusing on the sound quality and differences between all of the above.
General impression with my Westone 3 In Ear Monitors (W3, IEM's):
The first thing you'll notice when you plug into the GO-DAP and power it on is the lack of a loud pop. There's no hiss and very little background noise evident, except at the loudest volume level. The volume pot is free from noise or imbalance regardless of position. You start with a nice clean background.
The most immediate difference I hear between the iPhone Headphone Out (HO) and the GO-DAP is the change in the highs and mids. As desired by the designer/sound engineer, the highs and mids take a step forward. The highs are crisp and bright and the mid range is more detailed than the iPhone HO (although both sound a bit colder, yet smoother). When compared to the iBasso D4/LOD/iPhone combo the notices are more distinct. The D4 extends a bit further in every direction and is more detailed throughout. The bass region sounds tighter through the GO-DAP than the HO of the iPhone and it loses some punch/impact/depth/decay. The GO-DAP also loses a bit of warmth through the lower region as well. This might be welcome for owners of warm IEM's or headphones. The GO-DAP won't offend your ears. The highs are not overly harsh or bright and I do not hear any added sibilance. Feed the GO-DAP well recorded and ripped mp3's or ALAC files and you are rewarded. I don't hear a noticeable or severe spike in the mids or highs to speak of. The GO-DAP effectively sounds like an equalized (EQ'd) iPhone with the mids and highs raised a decibel or two through both ranges and the bass a few db down. The soundstage depth sounds more intimate (shallow) than the D4 and not as wide. The soundstage differences between the iPhone HO and GO-DAP aren't as noticeable. The width is similar and the depth is slightly larger out of the iPhone. The separation of instruments is essentially the same, but they do sound more detailed to me through the GO-DAP. The boost in the mids pulls the vocals forward and brings out the details of most instruments. Piano's sound a bit more defined, but lose a bit of the natural timbre, the horn section is sharp and guitars have bite. Cymbals are crisp and the bass drum is tight. You can identify the difference between an upright and electric bass. The kick drum doesn't overpower the bass or vice versa. The details in your music will shine through the GO-DAP.
The bottom line? The GO-DAP adds definition and clarity to the highs and mid range of my W3's (by bringing them more forward). It also tightens up the bass, when compared to the iPhone HO. The loss of soundstage depth is tolerable when you hear the details shine. The change in warmth does affect the natural timbre of instruments, but it's slight and acceptable for most genre's of music. Given that the Westone 3's are very efficient and don't require an amp to be driven to their full potential, I haven't felt the need to carry a portable amplifier, that may change now that I have the GO-DAP.
It's not really fair to compare the GO-DAP to the iBasso D4 as they are really the sum of their parts. The iBasso D4 is a purpose built standalone portable amplifier with a built in 24 bit/96 kHz USB DAC that offers Opamp rolling and is really in a different league.
General impression with the Shure SRH840 Headphones (840):
The Shure SRH840 are a full size, closed-back, circumaural headphone and are harder to drive than any IEM I own. They require me to raise the volume to 80% to 90% to obtain a normal listening level when plugged directly into the iPhone. Adding the GO-DAP makes listening to a full size can not only possible, but enjoyable.
As before. the first thing you'll notice are the crisp highs, followed closely by the accentuated mids. The SRH840 soundstage is fairly intimate, but not claustrophobic. There's not much of a change in presentation with the GO-DAP. I notice the change mostly in depth again. The elevated highs and mids bring instruments and vocals to a similar level and they seem to sound equidistant from the listener. I also hear a loss of warmth with the GO-DAP. It's not overly cold or sterile, it sounds tighter and a touch less airy. The differences are more apparent when compared to the iBasso D4. The D4 has better soundstage (depth wise) and retains a more natural presentation. Again, these changes are subtle and none of them are a deal breaker for me. If you have a set of headphones that are a little sloppy in the bass region and need a little help with the mids and highs, the GO-DAP can help. It's not a miracle worker, but it does clean things up nicely.
Until now, I've never considered taking my Shure's out and about, mostly due to their size, but given how well they isolate and perform with the GO-DAP, the idea is more appealing. On a side note, watching a movie on my iPhone was very enjoyable with the GO-DAP and the SRH840's.
Quick impression with Sennheiser HD600:
The Sennheiser HD600 was not designed to be a portable headphone (rated at 300Ω and open back) and needs about 95% of the iPhone's volume just to bring them to a listenable level. Even with that much volume, the HD600 isn't getting enough power to bring out their best. With the addition of the GO-DAP, the Senn's open up a bit and are more enjoyable. They're not at their best, but in a pinch the GO-DAP will allow you to hear most of their magic. The GO-DAP's influence is the same with the HD600, forward highs and mids and bass that I consider tight. The decay in the lower region seems to be affected by the GO-DAP. The decay seems shorter, which will make electronic music or pop music sound a little lifeless. However, with metal/hard rock the GO-DAP gives extra bite to the guitars and cymbals have a little more shine.
While clearly the GO-DAP wasn't designed to power the likes of a Sennheiser HD600, it's nice to know that it can do a fair job if called into duty.
Overall impression and conclusion:
The GO-DAP delivers exactly what the designers/engineers at VentureCraft wanted. A portable solution for the iPhone 3G/3GS with a specific sonic flavor. As intended, it reins in the soundstage and brings the vocals forward for an intimate experience. It's specialty may be Jazz, but it's not a one trick pony. It will do well with most genres of music. It's designed to make the highs shine and bring the mids out without sacrificing or inflating the bass region. This may be a big benefit for some listeners.
So if you're interested in a portable solution for your travels, the GO-DAP might be for you. When you factor in the cost of a 1450mAh battery extender/charger ($45 - $60), a quality Line Out Dock ($30 - $100+) and a quality portable amplifier ($100 - $300) the GO-DAP is priced to compete. Add in the ability to sync with iTunes or charge both units without taking your setup apart and I think you've done well for your money.