Accuphase a60 amplifier PCB Reference electric
Feature Accuphase a60
This circuit Accuphase a60 requires more electronic components. It belongs to Class A power amplifier. Need to use a large heat sink. It is recommended for audiophiles with rich diy experience. Entry-level diyer is not recommended to buy.
Adjust the quiescent current to 100-300mA per tube, the board has 1 TEST point, and the voltage drop at the test 2 terminals is 20-60MV.
Note: Remember to add mica flakes when installing the big tube, the mica flakes must be coated with thermal silica,
Operating voltage: AC 24V-0-24V ~ AC42V-0-42V + AC12V Note: AC12V is used to protect circuit. 2 channels require 2 transformers.
Output power: 200W 8 ohms 300W 4 ohms
Distortion: 0.002% S/N ratio: >100dB
Overview accuphase a60
Roughly three weeks ago, an AliExpress ad spam popped up showing me various clones or replicas of power amps. To my coincidence, I was looking for a second power amp just then, because I wanted to use Vidar for the speakers (Tekton Lore).
After Accuphase a60 glancing pages of products, an order placed on a whim as my self-birthday present. A few days later a big package was delivered to my place (from Hong Kong). And.. what’s in the box sounded surprisingly good.
The appearance has some shared design languages such as golden front panel or stereo VU meters. But it doesn’t look like Accuphase. Much uglier. There are some products intending to purely clone/imitate, which is not the case for the Weiliang’s amplifier.
Internally, Weiliang A60+ ‘s circuit quite resembles Accuphase A-60 whose schematic is on the catalog. Parallel input summing and voltage gain stages look noticeably similar (but not identical). Output stage largely departs from the original, which resulted in quite different amplifier specifications (Accuphase: class A rated 60Wpc; Weiling: class AB 200Wpc).
My conjecture is that Asian DIY folk(s) or community developed an amp based on publicly available A-60 schematic and perhaps reverse engineered to some extent. Then half-assembled DIY parts (amp pcbs also sold separately) or fully-assembled products are commercialised by various small companies such as Weiliang Audio.
This might be unethical in that those companies were unlikely to pay fair intellectual property royalty or give proper credits to the original contributor(s). But less blatant than complete copy products.
Anyway, Accuphase a60 does this amp sound like Accuphase?
I don’t know. I’ve only heard a couple of accuphase amps many years ago — with completely different speakers and upstream, unfamiliar tracks, and in show condition. I just remember it was very good, but hard to say anything more. Circuit similarity may result in somewhat Accuphase-ish sounding.. but only minimal at best. Just my guess.
Build quality is in line with JLH amp sold in Ebay or AliExpress (indeed it seems to have a similar process of commercialization). Not great but mostly acceptable.
Stereo VU panels on the front panels were honestly the primary reason I pulled the trigger. They don’t look as beautiful as big boys’ artful products. (Accuphase, Luxman, Mcintosh, etc.) But definitely gives me pleasure to stare. Accuracy is pretty poor, by the way.
Weiliang A60+ (henceforth referred to as A60 for convenience) is claimed to have maximum outputs of 40W (class A operation) and 200W (class B) at 8 ohm. For SR1a use, it mostly seems to operate in class A range. I don’t know if this is true. But this amp definitely consumes more power than Aegir and gets hotter. Also couldn’t hear any hint of amplitude-dependent sort distortions.
It’s the heaviest amp I’ve ever owned in the house — weighs around 47 lbs in my measurements. But it’s much lighter than big boy power amps spec’d similarly.
With no signal, A60 was dead silent so that I couldn’t hear any noise (preamp volume maximized). It didn’t have any pop noises in turning on and off, either.
Although this amp sounded quite good right after turned on, it relaxed a bit more over time. It seems that the amp reaches its max performance roughly after 15-20 minutes. But the improvement was only subtle if any (I also suspect the placebo effect). It sounded golden from the start. Indeed all three power amps (A60, Vidar, Aegir loaner) in the house had this more or less.
To me, the sound of A60 is best described with “golden”. And yes, I mean this amp sound a little COLORED, it’s definitely not the kind of “a wire with gain” style amps. Its tone and timbre have something shimmering and.. goldenly glowing, which has been mesmerizing me from day 1. Definitely warmer and more distorted than Vidar (and automatically than Aegir). This perceptual distortion is possibly dominated by the 2nd order, as it has nothing to do with harshness and roughness. It had a good bloom which I don’t usually expect from solid states. Honestly I will be surprised if A60’s harmonic distortion measures any lower than the Schiit power amps.
Overall tonal balance is a little on the dark and warm side. It actually enabled me to turn Loki’s 8k eq knob a bit clockwise than where I used to set (Vidar around 9’oclock).
The top end is where A60 had considerable success to my taste. While I admit it the sin of commission, higher frequencies shimmered enough to make me believe hearing songs and performances in the real theaters and concert halls. I kinda feel some sense of ‘goldenness’ in live performances, which is successfully faked through the combo of A60 and SR1a.
I couldn’t recognize the same level of wow with either Vidar or Aegir. (Other headphone-based combinations doing this similarly well include ECP DSHA-3F+ZMF Verite or Leptoni DT-Alpha+Senn HD800 from my first hand experience.) I think the highs just gorgeous with A60, especially when heard through a ribbon transducer.
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