On this evaluate, I’m taking the DROP + xDuoo TA-84 DAC/AMP for a whirl. The unit prices $299 USD and may be purchased from DROP.
Disclaimer: DROP and xDuoo usually are not associated to Headfonia. They despatched me the TA-84 to be featured on Headfonia.com.
DROP + xDuoo
Drop (previously Massdrop) is a California-based e-commerce platform that caters to many pastime lovers, together with audiophiles. Its most well-known providing is the collaboration with Sennheiser, which birthed the venerable HD6XX, a extra budget-oriented model of the HD650. I’ve personally purchased from them many instances, and infrequently, they provide some deep-cut decisions.
xDuoo Tech. Co., Ltd is a Guangdong-based audio gear producer. They first appeared publicly round 2011 and have made their very own private audio electronics in addition to served as a high-quality OEM for different manufacturers. Usually, xDuoo has stood out with fascinating tube-based designs and all-in-ones with swappable DAC playing cards.
DROP + xDuoo TA-84
The DROP + xDuoo TA-84 is an uncommon beast – it’s an OTL tube amp with a built-in DAC. Like most OTL amplifiers on the market, it solely has single-ended inputs and outputs as a result of differential tube electronics with out transformers are loopy troublesome to design and manufacture. Within the enter part, the TA-84 makes use of a pair of ECC82 (European 12AU7 equal), and a pair of EL84 pentodes drive the output.
Each are fairly inexpensive and plentiful tubes with many suitable equivalents. After all, when tube rolling, do seek the advice of the respective datasheets to double-check electrical compatibility and pinout.
Like with all OTL amplifiers, two elements should be stored in thoughts. Tubes like driving excessive impedance hundreds and with out a transformer isolating them from the headphones, they improve in energy supply because the load impedance goes up. Subsequently, the upper your headphones’ impedance, the happier the amp can be.
OTL output capabilities may be elevated with bigger energy tubes and through the use of many parallel tubes. For the reason that EL84 isn’t precisely crazy-powerful, the ability supply on TA-84 is kind of meager.
Separate from the amplifier part, we get a DAC board that’s primarily based across the ESS9018K2M chip. It will get the digital sign from a USB-C output after which sends it to the potentiometer, after which to the tube enter stage. So far as I can inform, the output stage of the DAC part makes use of op-amps.
The potentiometer is labeled “Alps RH2702”, and the case resembles the crowd-favorite RK27 “Blue Velvet”. The kicker is that there’s no information about “RH2702” on the Alps’ official web site, and plenty of speculate that it’s truly a replica. What’s extra fascinating is what’s inside! Because it seems, the RH2702 makes use of discrete resistors, so it’s a stepped attenuator as a substitute of a standard potentiometer.
It additionally has 4 pins per wiper as a substitute of the common three. The fourth pin is labelled “loudness” within the datasheet and apparently engages an RC-network to spice up the bass when the quantity is below round 11 o’clock.
When utilizing the quantity management on the TA-84, one can really feel the quantity steps, and certainly, across the center, the sound adjustments. In principle, making use of loudness EQ when listening at decrease volumes may be useful, however the EQ have to be utilized relying on the precise SPL that’s heard by the listener.
A potentiometer can’t know that, so the impact will depend on how delicate the headphones are. An fascinating resolution by xDuoo, however frankly, I might have most well-liked a daily RK27 as a substitute.
Options
- DAC chip – ES9018K2M
- Amplifier kind – tube, capacitor coupled (OTL) output
- Tubes – 2xECC82, 2xEL84
- Inputs: USB-C, RCA for line-in
- Outputs: 6.35mm TRS, RCA for line-out
- PCM information fee: as much as 32bit 384kHz
- DSD information fee: as much as DSD256
- SNR: 102dB amp, 113dB DAC
- THD+N: ≤1% amp, 0.002% DAC
- Achieve: +18dB, +20dB
- Output energy: 44 mW (at 100 ohms), 83 mW (at 300 ohms), 93 mW (at 600 ohms)
- Output impedance: ≤0.3Ω through 4.4mm; ≤0.2Ω through 3.5mm
- Energy draw: round 50W
- Dimensions: 10.6×6.4×4.6” (26.8×16.3×11.6cm)
- Weight: 3kg
Design, Construct & Haptics
Just like different DROP collabs, the xDuoo TA-84 has understated black appears. After all, the Pavane-made tubes nonetheless have their glassy silver appears, with small orange embers seen when the filaments are on. If that is your first tube amplifier, at all times alter your expectations of tube glow; most images exaggerate it through the use of lengthy publicity. I’m additionally joyful that xDuoo didn’t resolve to make use of LEDs to make the tubes brighter.
The entrance panel is nearly all-black, with the DROP emblem within the higher left nook and a standing LED that lights up when the machine is powered on. In my expertise the position of the ability LED is less-than-optimum as in lots of instances it will likely be eclipsed by the quantity knob. The 6.35mm headphone jack feels good, and the TA-84 is heavy sufficient so you possibly can plug your cans in with out holding the factor down.
A lot of the chassis is made out of anodized bent sheet metal with sufficient thickness by no means to have that low cost sound when tapped on. The entrance panel is milled black aluminum, and each the again and the underside panels appear to be aluminum as effectively. Taking the TA-84 aside is kind of simple, with most bolts having the identical Allen head.
The circuit is easy sufficient you can work out that are the coupling capacitors, however sadly, there’s little or no area to go wild with coke-can-sized esoterics. One thing like a Bottlehead Crack is manner simpler to mod to your coronary heart’s (and pockets’s) content material.
Versatility
Like many extra inexpensive choices, the TA-84 doesn’t have an influence button on the entrance, and it’s important to attain behind it to energy it on and off. Take care to not unintentionally press your hand on the recent tubes that may attain over +70C. They received’t instantly burn you want hotter-running massive energy tubes, however you possibly can damage your self by pulling your hand again instinctively.
The again additionally homes switches for acquire toggling and switching between the DAC and AUX RCA inputs. DROP specifies the acquire of the TA-84 as 16dB, however my very own measurements present that the voltage acquire is round +18dB on low and +20dB on excessive acquire. With a Sennheiser HD6XX, this meant that I used to be round midnight on the quantity management for many of my listening.
The knobfeel is peculiar, with very excessive dampening between the quantity steps.
After round 20 minutes of operation, the TA-84 settles on the thermal equilibrium of round +20 °C over the ambient. In my room, that meant the case was at toasty +45 °C, with the most well liked half being the ability tubes at +70 °C. As a result of the amp part runs in class-A, driving tougher hundreds won’t influence the temperatures.
The xDuoo TA-84 is shipped with Traditional-series Psvane tubes. A matched pair prices $40 for enter tubes and round $50 for energy tubes. Sadly, my ECC82 pair is kind of microphonic, so tapping on the amp or the desk the place it sits produces an audible “ping” sound on the outputs. I swapped out the inventory ECC82s for fancier RCA 6072s, and the microphonics went away.
Sound Signature and Technicalities
To check out the DROP + xDuoo TA-84, I used my Sennheiser HD6XX and ZMF Auteur Traditional headphones. Decrease impedance planars and dynamics would instantly present the boundaries of energy supply because the louder bass sections would turn into audibly distorted. All impressions are with the inventory Psvane Traditional-series tubes.
As at all times, I’ll begin with some practicalities. The TA-84 is rated for use with headphones with 100-600 ohm impedance. With OTLs, you possibly can typically bend the principles a bit and go decrease if the headphones are super-sensitive, however right here, the boundaries had been fairly pronounced, and it was simple to present clip the amp stage as decrease impedances shrink the accessible energy.
After all, most IEMs are out of the query as a result of +18dB minimal acquire and appreciable output impedance.
First, I connected my Topping Centaurus DAC to the AUX inputs of the TA-84 to see how good the built-in DAC is. The development over the built-in ESS DAC was evident, nevertheless it additionally made me notice that it’s no slouch. It absolutely didn’t make me really feel that I used to be lacking a lot of the music if I selected to make use of the TA-84 as a correct standalone.
I additionally felt that the built-in DAC was an ideal match to the hotter tube part as it could give it some additional chew that was lacking from the Centaurus matchup.
I additionally tried the TA-84 as a DAC/preamp for my FiiO SP3 energetic desktop audio system. The sign for the line-out is taken after the tube enter stage. Testing it was simple – I tapped on the inventory ECC82 tube, and the ping got here proper via my audio system. As for the sound, there was a little bit of tube heat, however usually, the sound was slightly impartial, with nice sound staging.
My solely criticism is the excessive acquire, which meant that I needed to maintain the quantity on my audio system very low.
The evaluate continues on the second web page with extra on sound. Click on right here or use the jumps under.
