Jul 22, 2005 at 1:40 AM
- Jun 27, 2004
- Reaction score
- Jun 27, 2004
Here is a new tube amp I bought off Ebay from an American Seller.
[This part deleted on 5/19/08 to remove seller information]
Judging from the appearance, this appears to be an alternative version of Sophia Electric’s Baby amplifier. Sophia Baby has received very positive reviews for driving speakers, and also gained reputation for driving K1000 as well. In addition, the Ebay model comes with a headphone jack. I was hoping this unit would satisfy all three of my amplification needs (speakers, headphones, K1000), so I took the risk of buying an unbranded and unsupported product.
Although this amp is branded Aria (model: MINIPL) on the box and Sonice on the machine, Google search indicates that these brands do not exist. I will call it the Aria amp for convenience. My research has led me to believe that Aria amp is produced by Yarland audio in China. I believe several other Sophia amps are also produced by Yarland. Since Yarland’s website in China does not offer any product that looks like Sophia Baby, I am pretty confident that Sophia Electric is not just simply repackaging Chinese amps. There is one important difference between Aria amp and the Baby amp. Baby amp uses 6P1T Russian military tubes, and my model uses the common EL84/6BQ5/6P14 tubes. 6P1T is a special military tube that can only bought from Sophia Electric (Google search yields nothing). It is similar to Russian 6P14 (EL84/6BQ5), but 6P1T and 6P14 are not interchangeable. There are four adjustable resistors inside my amp, and I suspect that 6P1T and 6P14 versions differ only in bias setting.
My amp has a headphone jack, which was optional on some earlier models of the Baby amp. Enjoythemusic.com once reviewed a model of Sophia Baby with a headphone jack. Sophia Baby amp now retails for $899, and the headphone jack used to be a $100 option.
The pre-amp section of Sophia Baby is said to be passive. The driver tubes are 5670/396A/2C51/6N3. The stock tubes I received are labeled Beijing 6N3. Chinese 6N3 is equivalent to Russian 6N3P, and are compatible with 5670/2C51 and Western Electric’s 396A. The stock power pentodes are labeled Beijing 6P1J, also called 6P1 in China, which is compatible with EL84/6BQ5 and Russian 6P14. Two power pentodes work in push-pull configuration to achieve 10 W per channel. Sophia Electric calls its Baby an S.E.T. music amplifier, which is kind of misleading because S.E.T. is a trademark, and the amp is push-pull, not single-ended. According to press reviews I have read, the Baby amp is “class A” push-pull. For an excellent discussion of class A single-ended vs class A push-pull vs class AB push-pull, see this link.
My unit is basically half-finished in terms of cosmetics. The knob, the switch and the RCA terminals are not polished. The decorative wood blocks remain white and unpainted. I had once seen a cosmetically finished unit on Ebay-Taiwan, also branded Aria. I plan to paint the wooden parts myself, and maybe even replace the volume pot. BTW, the 6N3 tubes glow more than EL84 in the dark only becuase there are 2 red LEDs below the sockets.
The transformers do produce an audible hum. Some of the sound comes from outer casing resonance. Putting a nickel on the casing (see picture) successfully reduces the hum. After this, the hum is only audible from about 3 feet away, and basically becomes unnoticeable during normal listening. The volume knob does not turn exactly smoothly near 8 and 4 o’clock positions, but channel balance is not a problem. The headphone jack is wired oppositely for left and right channels, but this can be compensated by inverting the speaker connections and does not cause any real problem. The headphone jack has noticeable noise. The noise is just noticeable using K501, but easily audible using PX100. When K1000 or speakers are connected through the speaker binding posts, there is no audible noise. The amp is probably designed as a speaker amplifier, and the self-noise is audible for these applications, even at full volume setting. Headphone jack is probably an afterthought, and self-noise becomes noticeable since headphones are much more sensitive. Using multimeter, I found that the headphone jack is connected to 100 ohm resistors in-series. Therefore, the headphone jack is most suitable for high impedance (120-600 ohms) headphones such as K240DF, HD650 or DT880.
There are quite a few choices for 2C51/6N3P tubes. 5670/2C51 tubes are much shorter than Russian 6N3P but the specs are fully compatible. It appears that current production tubes are only made in Russia (6N3P) and China (6N3). Many American NOS tubes are available: GE, RCA, Raytheon, Sylvania and Tung-Sol. It is widely thought that Western Electrics’ 396A is the finest NOS 2C51. I decided to go for the best and bought a pair of WE tubes from Antique Electronics Supply, because I am afraid of getting fake tubes on Ebay. For EL84 there are too many choices. I decided on JJ Tesla’s EL84 because they are said to sound warm and matched quads easy to find at inexpensive prices.
Using WE 396A, the amp sounds too bright and brittle. There is more detail compared to Chinese 6N3, but I can’t stand the hi-freq shrill that comes with it. I prefer the warmer and more balanced sound of Chinese tubes for driving K1000, K501 and speakers. This is my first experience with NOS and I am not impressed. I guess it is simply too naïve to think “tube A” will always sound than “tube B” in every application. Switching between Chinese 6P1 and JJ EL84, the difference is smaller than switching 2C51 tubes. JJ tubes sound warmer and I prefer that.
CD Transport and SACD player: Sony DVP-NS900V
DAC: Benchmark DAC1
Headphones: AKG K501 (headphone jacks), K1000 (speaker terminals)
Speakers: Athena S2/P2
Aria tube amp with Chinese 6N3 and JJ Tesla EL84
Amps for comparison:
K501: DAC1’s XLR and headphone jack
K1000 and speakers: Jolida JD301A ($350), modded Jolida JD102B ($950), Sonic Impact T-amp ($30) connected to SLA battery ($40)
Note: Modded Jolida JD102B is kindly lent by Randytsuch
Since the four amps being compared are all speaker amps, I hooked them to my $1100 Athena S2/P2 combo. S2 are passive bookshelf speakers docked onto P2 active subwoofers to form powered tower speakers. Comparing T-amp to Aria amp shows the classical SS vs Tube distinction. T-amp is extremely fast, clean and resolving, with great dynamics and imaging. Treble on T-amp is a bit too sharp, and on a good recording this creates a brilliant sound that sparkles, but on a “bad” digital recording it becomes lean and shrill. In terms of resolution and bass authority the Aria amp falls slightly behind the T-amp, but the harmonic richness and warmth of tubes compensates awesomely. I would call it a tie between the T-amp and the Aria amp. Choosing between the two IMO comes down to system synergy and personal taste. In my current setup I prefer Aria amp a tad more, and the Aria amp can play 3-5 dB louder. Considering the fact that properly retubing Aria would cost more than the T-amp/battery setup, T-amp’s performance is nothing short of a miracle.
Stock Jolida JD102B is priced at $580, and the unit I borrowed from Randytsuch (big thanks to Randy) was modified by Response Audio and goes for ~$950. Capacitors, resistors, diodes and volume pot are upgraded and balance knob is bypassed. It uses 12AX7, 12AU7*2 and EL84*4. It is push-pull, class AB1 ultralinear design with 20 W output. In contrast, Aria amp avoids crossover distortion at the expense output power by using class A push-pull. To me JD102b sounds smoother and more laid-back and this really helps with overly bright CDs. However, smoothness comes at the expense of resolution. Compared to Aria, JD102 is slightly worse in terms of bass impact, imaging and transparency. On good recordings I like Aria more because it brings me closer to the performance, but on bad recordings JD102 provides the saving grace to keep music enjoyable.
Hence, it is basically a three-way tie between T-amp, Aria and JD102, and Jolida JD301A in its stock form is only falling slightly behind. While JD301 has SS-like bass and tube-like warmness, its performance is somewhat unpredictable. This hybrid amplifer (12AX7+LM1875 OP-AMP) sometimes brings together the best of both worlds and produce a dynamic (SS) and sweet (tube) sound. On other recordings, it can sound a bit dull (SS) and slow (tube). Of course, the differences discussed here are subtle and come in shades of grey (not day and night). JD301 is comparable to Aria in terms of bass and resolution but can’t match the latter’s full and organic sound.
One thing that worries me about buying an unbranded Chinese amp on Ebay is that it might be a product that did not pass the QC to be sold normally. I have never heard the original Sophia Baby amp, so I can’t say if my Aria amp would sound the similar despite the different tube configurations. To my ears, the Aria amp does perform as good as a modded JD102 (~$950) ad a stock JD301 ($350). Given the good reputation of Jolida in budget tube amps today, I would think the Aria amp is worth $899 in terms of sonic performance.
My main purpose of purchasing the Aria amp is to provide more warmth for K1000. I previously used JD301 to drive K1000, which IMO sounds better than T-amp because of tube warmth. Now I throw in two tube amps and it becomes a four-way comparison. T-amp is the worst performer in the group, although it does have more resolution than any other amp. The main problem with T-amp is its brightness, which turns into a slight shrill when paired with K1000, which is a bright headphone. JD301 has a smoother sound than the T-amp but still sounds a bit thin. JD301 seems to sound better driving K1000 than driving speakers, especially in terms of resolution. While JD301 may be slightly more resolving than Aria amp driving K1000, Aria amp exhibits richer harmonics and a fuller, warmer sound that keeps the brightness of K1000 in check. On good recordings, Aria+K1000 strike a nice balance between transparency and harmonics. On mediocre recordings, the treble becomes a bit dry and lean. While Aria amp does not provide enough smoothness to mask the treble artifacts in sub-par CDs, modded JD102B excels in this regard. With JD102B, mediocre CDs become more enjoyable because the treble brightness is made darker and harmonics becomes emphasized. Instruments sound smoother with richer tones. However, the added smoothness comes at the expense of details and transparency. The overall sound of JD102 is a bit recessed and instruments sound a bit too distant. While its laid-back nature works great for poor recordings, JD102 lags behind Aria in terms of fidelity when playing good recordings. I would call it a tie between Aria and modified JD102B. JD301 comes in rather closely as the third and the T-amp is too bright to be enjoyable but it remains the resolution king.
I have already mentioned that there is one 100 ohm resistor per channel between the headphone jack and the output transformer. The resistor probably serves as a protection mechanism in case low impedance headphones are connected. There are two potential problems associated with using low impedance headphones here: frequency response alteration and noise. If the impedance of low impedance cans varies significantly with frequency, the resistor is going to cause unevenness in frequency response. With K501 I can hear audible noise without input signal. The noise sounds like a hum to me, but there is also a buzz in left channel when the volume pot is at the lower settings. Turning up the volume pot to 12 o’clock, the buzz is mostly gone. The noise is affected by the choice of tubes, and again Chinese 6N3 is better than WE 396A in terms of noise. However, with speakers or K1000 there is no audible noise, which is consistent with the 90 dB S/N ratio (Ebay specs). Setting the volume pot at 12 o’clock and using my DAC1 to control the volume, noise is not a real issue with K501. Even Diana Krall’s “When I look into your eyes” CD has a similar level of background noise, which is recorded using all-tube equipment. Diana Krall’s CDs have won critical acclaim for sound quality, so I guess a little bit of noise is not so bad. Anyway, I think Aria’s headphone jack is most suitable for high impedance headphones.
I don’t have a dedicated headphone amplifier at home. The built-in headphone amplifier of DAC1 is not bad, and some head-fiers say it is comparable to basic PPA or Pimeta, which I can’t verify. The XLR output of DAC1 is apparently a better headphone amplifier, which is what I normally use. I modified Hosa XLR-to-RCA adapters to float pin 3 (negative signal). RCA to mini plug adapter allows me to use K501. Aria amp sounds a bit less detailed but significantly smoother, warmer and harmonically richer than XLR. Surprisingly, Aria amp is significantly better in terms of ambience, airiness and depth, which significantly improves the coherence of K501’s soundstage. Bass performance is about equal, since Aria has a fuller but slower bass. In the end, I prefer Aria’s jack substantially more than the XLR, especially in terms of musicality. IMHO, the lack of musicality in music playback is often due to the lack of ambience and harmonic richness. Aria amp substantially improves K501 in these two regards. I have basically stopped listening to XLR after I got the Aria amp. Aria+K501 kind of me reminds me of the LP sound: not noise-free, smooth and airy, diffused and a bit distant; full and rounded bass (K501 still lacks bass extension in the lowest octave, though).
After buying the Aria amp, I realized that buying unbranded products off Ebay is pretty risky. There is no manufacturer support or customer service, and quality control is nebulous at best. Fortunately, my Aria amp turns out to perform pretty well and is consistent with the specs listed on Ebay. There are a few glitches but nothing that compromises the sound. I am curious about comparing the Aria amp to its cousin, Sophia Electric Baby amp. The fact that Aria amp sounds at least as good as a modded Jolida JD102B, another EL84 amp as expensive as the Baby amp, makes me feel pretty good about this purchase. In the four integrated amp shootout, I prefer the Aria amp for both speakers and K1000. I have bought an Adcom speaker selector to allow the Aria to drive both. As for the headphone jack, it sounds very musical with K501 but not most transparent. There appears to be some coloration but it turns out to be quite euphonic, both sonically and emotionally. I had high hopes when I first bought the Aria amp, wishing it could surpass my previous amplification devices for speakers, K1000 and K501. This is a tall task for a <$500 amplifier, but to my delight it has succeeded. While it brings substantial improvements to my speaker and K1000 listening, the real transformation occurs with K501. It took K501 to a euphonic state that I did not expect just by adding tubes to the signal chain. Recordings not very enjoyable on K1000 because their weaknesses are revealed are now getting delegated to K501.