TRENDS AUDIO PA-10.1D SE
text and photo: Marko Pecotic, February 2018.
product: Trends Audio PA-10.1D SE headphone amplifier/line preamplifier
manufacturer: ITOK Media Limited - Trends Audio [www.trendsaudio.com]
price: 279 EUR + duty, tax and shipping cost
Trends Audio, a Hong Kong manufacturer of baby sized audio devices, has established itself on the market with its' small digital amplifiers based on Tripath chips, in
the meanwhile their catalogue has been expanded to preamplifiers, headphone amplifiers, DACs, power supplies, cables and speakers, and the object of this review is their
PA-10.1D SE hybrid headphone amplifier/line preamplifier. If ordered directly form the manufacturer, it'll cost you – my rough estimate – appox. 350 - 400 EUR (all the duties,
taxes and shipping costs included). If ordered within the EU, it'll cost you like 369 EUR + shipping cost (if
ordered from the Nederlands), or 269 GBP + shipping cost if ordered
from the UK.
A few words from the press material. This is a low voltage hybrid amplifier, the tube works as a voltage amplification, plus two mosfet drivers at the output. You can choose between these versions: standard verison (comes with a chinese 6N11), the SE version (comes with a soviet 6H23N) and the GE version (comes with an american 12AU7), while a future owner can use any other tube from the 6DJ8/6922 or 12 AU7 series. The expected life of of the russian tube should be up to 8 to 10 thousand working hours. The tube replacemet goes very easy, just follow the instructions from the manual and set the bias at 16,5V.
Inside the box you'll find the amplifier (with a factory set bias), one tube, a 24V supply, a manual and a screw driving potentiometer. You can use the 24V power supply or you can buy the external PW-10 PSU, that'll – as the manufacturer says – improve the PA-10.1D SE sound for like 25-40%.
The front consists of an Alps volume pot and a 3,5mm headphone out. The back consists of one RCA input and two outputs (if you want to drive, say Trends Audio monoblocks or one stereo power amplifier plus a subwoofer), power on/off swith and a gain switch (3x or 6x).
A few words from the manual:
- Do not leave Trends PA-10.1D unattended for long lengths of time during the 22 hour initial burn-in.
- The sound of Trends PA-10.1D will open up after about 5 minutes of warm-up. At least half an hour of warm-up, if you are doing some audiophile listening.
- Always wait at least 5 minutes prior to turning Trends PA-10.1D back on after turning it off.
- We suggest that you turn on the Trends PA-10.1D preamp first, the power amp second; we suggest that you turn off the power amp first, the PA-10.1D second.
- RCA outputs are not muted when headphones are connected to the preamp, the outputs are simultaneous.
- PA-10 Tube Headphone/Pre Amplifier supports two major tube series: (1) 6DJ8, 6922, 6N11, 6H23n, ECC88, E88CC etc and (2) 12AU7, 5963, 5814, ECC82 etc. If you change the tube within the same series, it needs to re-tune the DC bias voltages ONLY. If you change the tube from another series, it needs both to re-tune the DC bias voltages and re-set the jumpers. Otherwise, the tube may be burnt out. For more details, please read Bias Setup.
The manufacturers claims it can deliver 3W (!) into a 3 Ohm load, works in A class and can drive 16-600 Ohm headphones. It has a relatively high output impedance declared at 30 to 100 Ohms.
A little bit of technical stuff
In general, an amplifier itself is a sum of all integrated parts and implemented data, but perhaps just by knowing the declared (high) output impedance, I got a hunch that perhaps you could predict what it will sound like (warmer sound with a voluminous bass?). In general, headphone amplifiers with as low as possible output impedance should sound better than those that have high output impedance (higher el. damping factor, less distortion, more natural sound etc). The amplifier's output impedance should, it is desirable, be at least 10x lower than the output impedance of a (dynamic) headphone (if natural sound is what you're looking for). In other words, the lower the output impedance of the amplifier, the wider is the choice of headphones.
Some might say that, in this context, damping factor is irrelevant, arguing in favor of headphone drivers being very light (unlike those that are built in speakers). At first this might seem to be true and correct, but it is not so in reality. A classic example is Beyerdynamic, a german headphone manufacturer, which offers the same headphone model in different impedances. Imagine a, say 100 Ohm output impedance headphone amplifier connected to 32-Ohm Beyers, then connected to 600-Ohm Beyers. The 32-Ohm model will sound unnatural and boomy, while the 600-ohm model will sound more balanced and natural. Sure there are people who will intentionally "break" the 1:10 rule to get less natural and more atractice sound.
Most manufacturers do not specify output impedances of their headphone amplifiers. Why? I've no idea. You should address this question to them.
Some manufacturers say high output impedance has a protection function and is there for security reasons. And they will be right. The (high) output impedance will protect the amplifier from a short-circuit if occured on the headohone/cable side. High output impedance will protect both headphones and ears if you plug and unplug various headphones, like if you go from low-sensitivity headphones to high sensitivity ones.
Zero output impedance is an ideal. We don't live in an ideal world, so while it can be done with transistor amplifiers, it's not the same when it comes to tube amplifiers. Perhaps this is why owners of headphone tube amplifiers often say they get the best sound results with high impedance headphones.
Although it can serve as both a line preamplifier and a headphone amlifier, I have reviewed the headphone stage only (I guess both should sound similar). I let the PA10.1D SE burn-in for some 150 hours, and have tested it using these headphones: AKG K701, Beyerdynamic DT 990 (600 Ohms), Sennheiser HD600 and Beyerdynamic DT 880 (600 Ohms).
The amplifier was – as the manufacturer says – delivered with the bias set to 16,5V. After about 300 hours, we have measured the bias and the results were as follows: 17.8V – left channel, 17.33V - right channel, and was set back to 16.5V (thanks, Ilimzn). This means that the PA-10.1D SE will require constant care due to bias voltage shifting (a future owner should check and set the bias few times a year).
Moving the volume control up and down goes very smooth, without the scratchy feeling, though rotating the volume control up and down will cause a slights noise in the headphones. Also, I wish the amplifier had some sort of a tube protection, say a small cage.
The RCA connectors are placed close to each other, which means that you can easily connect an interconnect cable with RCA connectors with a diameter up to 13 mm.
It's important not to judge the sound of this amplifier if you're not patient. After the initial 100 or 200 hours of burn-in, it will take about 20-30 minutes for the amplifier to warm up every time you turn it on, and during those 20-30 minutes it will sound blurry, undefined and compressed.
In general, the sound of this amplifier is somewhere between neutral and warm. For best sound results, you should not connect it to warm or blurry sounding headphones, open and detailed sounding headphones should be a better choice.
If I were to describe this amplifier in a few words, I'd say the following: fast, big sounding, dynamic, full bodied and not boring. Bass area is slightly emphasized (it's deep and voluminous, and not correctly defined) which results with a smooth mid area. Important to say, the bass has no irritating boom-boom effect, it does not dominate over the rest of the frequency spectrum.
The grand piano sounds very good, big, fast (good timing), with good dynamics. Because of its' smooth mid area, it will not deliver the tiny micro-dynamic details (and this is not something I'd expect from an amplifier in this price range), but in general the piano has a good definition and separation of its' keys, it sounds big, has nice dynamics, attack, sustain, timing etc.
With the mid area being soft and slightly reduced (not over dumped) and the bass being slightly emphasized, the brightness and sharpness of bad recordings will be reduced by adding more body into such recordings. Especially if your source is, say an iPod which usually sounds thin.
The PA10.1D SE will sound good with all musical genres. It has a sufficient quantity of details, it's big and dynamic, not blured. Electric bass guitar or double bass lacks a clearer distinction of each tone and each single wire, the 10.1D SE is more focused on bass volume.
The symphony orchestra sounds great, the instruments have a full body, a slightly more pronounced bass stimulates the dynamics and transients of the orchestra, but with a not as good soundstage focus.
Should you set gain at 3x or 6x? The answer depends primarily on the source you are using. Classic portable players usually have output voltage of 250mV to 1V, while the output voltage of a CD player is usually around 2V. In other words: if your source has a lower output voltage, the gain on PA10.1D SE should be set to high.
Does it really have the declared 3 Watts on 33 Ohms? I'd say no, it does not. I think this amplifier has up to 0.5 or 1 Watts (which is still lots of power). The 10.1D SE drove all four headphones well. For most of the time during the review, the volume control was set at 9-9.30 H (for moderate volumes) or at 10-10:30 H (for higher volumes). The gain was set at 6x, and was connected to a CD player that supplied 2.5V.
To test the upper limits of the amplifier, I played a solo drum recording, turned the volume control to highish 11 H (gain set high), and waited for a line dominated by the floor tom and bass pedal. The PA10.1D SE clearly demonstrated its' limits, this is where the K701, DT880 and DT990 sounded distorted, while the HD600 did that line without any distortion (I had to set the volume control lower, to ca. 10.30H, because the HD600 was louder and more sensitive than the other three headphones).
The 10.1D SE has clearly and correctly showed the differences in sound between all four tested headphones. It presented the K701 as a headphone with a beautiful mid range (air, freshness, openness), it presented the DT-990 as an attractive (loudness) sounding headphone, it presented the DT-880 as a more-less well balanced sounding headphone...
In terms of sound sinergy, the PA10.1D SE sounded the best with the K701 and DT-880.
Considering its price/sound ratio, my final score for the PA10.1D SE is: 8/10.