The Apple Thunderbolt Display Review
by Anand Lal Shimpi on September 23, 2011 2:56 AM EST- Posted in
- Displays
- Mac
- Apple
- Thunderbolt
- Thunderbolt Display
Trouble in Promise-land
What's the first thing you do when you've got a display that has tons of interfaces and bandwidth at its disposal? Try them all at once to see if anything breaks of course. Over the course of the past few days that's exactly what I did. Unfortunately I did find a situation where things broke.
For whatever reason, if you're doing a lot of writes to the Promise Pegasus while playing music (or any other constant audio) through the Thunderbolt Display's internal speakers the audio will eventually corrupt. You can hear exactly what I'm talking about below:
TB Pegasus Audio Issue by AnandTech
This is a recording taken of me listening to music on the Thunderbolt Display (via its internal speakers) while writing a couple hundred gigabytes to the Pegasus R6. Note the introduction of what can only be described as really bad noise at the 6 second marker.
If you stop music playback and quickly resume, the problem will still be there. You have to restart the application that's using the audio codec to recover from this point. From a hardware standpoint, the codec just needs to go through an off/on (sleep/wake?) cycle to return back to normal. If you do this however and haven't stopped the transfer, the problem will creep up again. Stopping the transfer while playing back music won't fix the issue either. You have to stop the transfer and restart the music playback application for it to go away.
The issue goes deeper than that. I went out and bought a Creative Labs X-Fi Go Pro USB sound card to see if the problem stopped at the internal audio codec or extended to all USB sound devices. Unfortunately, it does even happen if you're using an external USB sound card connected to the Thunderbolt Display. Connect the same sound card directly to your Mac or use your Mac's 1/8" stereo jack and the problem goes away.
I was worried that what may appear as noise through speakers could result in data corruption over USB transfers. I ran the Pegasus write test while copying a bunch of files to an SSD attached via USB to the Thunderbolt Display and never saw any corruption on the SSD. This appears to be limited entirely to audio playback.
What's truly bizarre is I can only get the issue to appear when writing to the Pegasus, hundreds of GBs of sequential reads don't seem to produce it. Short bursts of writes don't seem to cause it either. Sending tons of data across the monitor's Gigabit Ethernet, FireWire 800 and USB ports doesn't seem to trigger it either. It appears to be an issue with the Pegasus and the Thunderbolt Display. But which device is ultimately at fault? Is it a problem with the Thunderbolt Display or the Pegasus? Ideally I'd use another Thunderbolt storage device to see if the issue remained, but I couldn't get my hands on a LaCie Little Big Disk.
I thought of something else.
First I needed to test and see if perhaps the issue was related to ultra high speed transfers. As we've already shown, the Pegasus can push as much as 1GB/s over Thunderbolt whereas none of the other bandwidth eaters come even remotely close to that. To determine if the issue was data rate invariant I wrote to the Pegasus at different speeds ranging from 480Mbps all the way up to 7.2Gbps. I tried putting SSDs in the Pegasus as well as standard mechanical hard drives. The problem remained. I got audio corruption regardless of what drives were in the Pegasus or what speed I wrote to the drives. The problem wasn't related to transfer rates.
I also took apart the Thunderbolt Display to confirm there weren't any obvious issues on the controller board (E.g. putting the Thunderbolt IC far too close to the audio controller). Nothing obvious there either.
While I was doing all of this, Apple put forth a Thunderbolt firmware update the other day, however it didn't seem to address the issue either. So I went back to my testing.
Since the problem appeared regardless of how fast (or slow) I was transferring and all I needed was another Thunderbolt storage device to vindicate either the Pegasus or the Thunderbolt Display I turned to the trusty MacBook Air.
As I mentioned in our original Pegasus review, if you have two Thunderbolt equipped Macs and a Thunderbolt cable you can actually put one of the machines in target disk mode and access its drives via Thunderbolt on the remaining Mac. You don't get super high performance but you can get around 500Mbps. Since I had reproduced the audio corruption issue at an even slower data rate I decided to give this a try.
I booted the MacBook Air in target disk mode by holding down the 't' key after turning on the machine. My MacBook Pro was connected to the Apple Thunderbolt Display and a Thunderbolt cable connected the display to the MacBook Air. This was the same setup as the Pegasus, but with the MBA in place of the Pegasus.
I wrote to the MBA just like I did the Pegasus (from a file server connected over the Thunderbolt Display's GigE, transfer rates were capped at around 500Mbps from the file server). After a couple hundred gigabytes were transferred without any audio corruption I swapped out the MBA and connected the Pegasus. I copied the same files at the same rate from the same source. After no more than 7GBs were written to the Pegasus the audio stream started to corrupt.
Based on my testing I can only conclude that the Pegasus seems to be at fault here, not the Thunderbolt Display. Given that the Pegasus was introduced prior to Apple's Thunderbolt Display it's not all that surprising that this issue made it through to production. It's unclear what the root cause is but it's hopefully something Promise can address either through firmware or a driver revision.
Update: I'm still verifying that this is indeed a "fix" but it looks like if you use a USB sound card plugged into a USB hub which is then plugged into the Thunderbolt Display then the sound corruption doesn't happen. This seems to point at noisy power as being the cause with the USB hub acting as a crude filter. It's still not ideal but this may be a workaround for Pegasus users until Promise supplies a fix.
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CharonPDX - Friday, September 23, 2011 - link
I had HOPED to buy either a Mac Mini or a MacBook Air this year. Finances aren't allowing that.But, it looks like sometime mid next year, I should be able to upgrade.
At this point, if Anand's wish comes true:
I'll be getting an 11" Ivy Bridge Air and a Thunderbolt Display.
Death666Angel - Friday, September 23, 2011 - link
"capable of at least 350 nits at full brightness"Just wanted to say that Apple actually advertises 375 cd/m² on their website. :-)
tzhu07 - Friday, September 23, 2011 - link
I wish Anand would've addressed the issue of the glossy-only screen option in the video review. Why did Apple and some others continue to seemingly promote this type of screen? There are many people that consider it a deal-breaker, including myself. How much of a hassle is it for Apple to have two variations of the same product?repoman27 - Friday, September 23, 2011 - link
"While the display does feature a pair of integrated speakers, they don't produce the best sound in the world. Thanks to their diminutive size and unusual enclosure, the speakers don't cover a lot of dynamic range and you can forget about any ultra low frequencies. If you like bass, you still need a sub."According to Apple's specs, the ATD has a 2.1 speaker system, so it already has a sub of sorts. Also the claimed power for the audio system is 49 watts, which is pretty staggering for something built into a display. Actually it's good compared to most compact PC desktop speaker systems. It's too bad that it impresses more on paper than it would seem to in real life.
dunce - Friday, September 23, 2011 - link
Can I use that Thunderbolt port on the back to plug in a second computer (MacMini/PC)? I am looking at this and the Dell 27in but would like multi computers inputs.Constructor - Saturday, September 24, 2011 - link
No, as far as I'm aware there can only be one master (CPU) on a Thunderbolt chain.kalistan919 - Friday, September 23, 2011 - link
Will Thunderbolt connections be available for the new 28nm gpus that are coming from AMD and Nvidia? Or will Ivy Bridge channel your discrete gpu from the gpu to motherboard to display through a thunderbolt connection on the motherboard? Does anyone know if Apple will come out with a 30" Thunderbolt Display like they did just recently with the 27" display?These are three questions I tried to find but couldn't. Here's another one...would a minidiplayport on the GPU card work with an apple thunderbolt monitor? Anyone have the lowdown on this? Thanks in advance.
ggathagan - Saturday, September 24, 2011 - link
The GPU's themselves do not dictate what type of connection is used; that's up to the video card manufacturer.Remember, however, that Thunderbolt is not a GPU-specific interface, so a discrete video card with a TB connection would require the manufacturer to add the TB controller and its associated circuitry to their video card.
I doubt that'll happen.
Ivy Bridge will not have integrated TB, so the answer to your 2nd question is also "no". The motherboard would have to take the video output, whether from the CPU or from a discrete GPU, and route it through an on-board TB controller.
30" displays are going away in most market sectors, so I doubt you'll see a 30" with Thunderbolt.
More specifically, I doubt you'll see *any* 30" display from Apple in the future.
As to your last question; from the article:
"A Thunderbolt cable can only transmit a Thunderbolt signal. Although DisplayPort is muxed in, if the display on the other end is expecting Thunderbolt and it receives DisplayPort it won't know what to do with it. It's possible Apple could have built in logic to autosense and switch between Thunderbolt and DisplayPort as inputs, but Apple traditionally employs clean breaks rather than long technology transitions. If Apple wants to ensure Thunderbolt gets adopted (at least by its users), this is the way to do it. "
According to this discussion at Apple's site, someone tried using a non-TB MBP and MBA and were not successful.
https://discussions.apple.com/thread/3199231?start...
What I would expect to see is someone marketing a Thunderbolt adaptor that converts a DP input to TB output.
In fact, I would expect to see Apple create this eventually, but it'll be atrociously expensive from them.
Since the whole point of TB is the ability to bundle multiple types of data traffic through a single interface, the only scenario where using a TB-equipped monitor currently make sense is one like this article describes; as an alternative to a docking station for a laptop.
It *would* make sense for a display manufacturer to make a TB-equipped monitor that could auto-sense with the input is DP or TB, but only if you're taking the same approach as Apple and include LAN, USB, audio and FireWire connectivity in the monitor.
If, for instance, Dell were to create a line of TB-equipped monitors with all the connectivity I described above, they could market those monitors in conjunction with a TB-equipped desktop and/or laptop series.
The desktops would only require the TB cable and a power cable; the monitor would handle all the peripheral connections.
Essentially, however, you end up having to decide if you want all your connections at the monitor or at the computer itself.
Historically, people prefer to limit the number of cables hanging off of their monitors and leave the rats nest at the computer.
Where I think TB hold the most promise in relation to desktop systems is in the area of external storage, like the Promise Pegasus Anand mentioned.
Impulses - Saturday, September 24, 2011 - link
Usually I skip video reviews entirely unless it's something that's just not communicable easily in text (factory tours and game trailer for instance)... They just tend to ramble on and/or provide very little info.However, the video on the first page of this review was excellent! You should've started doing these long ago, I actually read the entire review first even tho I'm not even remotely interested in the display (I am curious about Thinderbolt's future tho), and I started front to back as I often do (by reading the conclusion first and then skipping to other interesting parts). Having read the whole thing previous to watching the video I feel like the clip actually did a better job at summing it all up than the conclusion or Final Words, which is very impressive, great job!
ppayne - Saturday, September 24, 2011 - link
I'd love to see mods for this appear. Imagine 2 2.5 inch hard drives wired inside somehow and accessible through Thunderbold?