• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Can a experienced DIYer tell the quality of a 845 amp by looking at the internals?

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I hope I'm asking the right place. There is not a lot of knowledgeable talk outside this forum on 845 tube amps.

After reading the reviews from stereophile & stevehuffphoto, I wanted to try one, but the measurements from stereophile steered me clear away.
The Line Magnetic 518ia SNR is stated to be 87dB, but actual measurements show a incredibly bad 65.6 dB.
I definitely don't want noise in a expensive amp, but looks like Chinese made 845 amps are the only option unless I want to spend $10k on a quality U.S. or European amp.

Can anyone at a glance check the internals of some affordable Chinese 845 amps & see if the quality is superior than the rest? All I know is that having more transformers is usually a good sign.

Muzishare $4k 845 amp
RvCbjTD.jpg



Cayin $4k 845 amp
Ptd8GP1.jpg



The Muzishare & Cayin offer options to turn on or turn off negative feedback, which the other amps don't.


Line Magnetic 518ia $3k
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There is a Singapore Edition (not pictured) that they sell with upgraded Vishay Resistor, Vishay Capacitors, Kiwame Resistors, Mundorf Oil Coupling Capacitors & Mundorf Power Capacitors. Would those upgrades help the noise floor from the Stereophile review sample?

There is also the much cheaper Line Magnetic 218ia, which has the internals look almost identical to the 518ia
kTb7fYO.jpg


And the cheapest of all 845 amps I found.
LaoChen 845 tube amp at $1,000!
uEUcSFk.jpg

No internal pictures, but can it be possible to make a quality 845/300b tube amp for just a grand?


I feel if I don't like the sound, a loss of a $1000 is better than a loss of $4000?
Then again Line Magnetic is the only Chinese amp that had legitimate review publications review & vouch for it.
With Cayin being a more mainstream company with possibly a better reputation than the rest?
And the Muzishare looks to have the most parts & the only one with a all-aluminum chassis.

Can anyone give their opinions on which route to take?
 
Looks pretty well put together but is that the exact amp? Anyway... its the transformers that are impossible to see and the most important component.


I would not buy a tube amp without knowing what the trannys are which renders most Chinese amps non-starters... (and most other Asian Country's w the exception of Japan and a few companies out of S. Korea.
 
The translation for the Muzishare says
"Two EI single-ended output transformers with high quality special process and high quality wide frequency response made by Z11 core"

The Cayin amp states
"Two high quality wide frequency response EI output transformers
Use a ring power transformer specially developed for this machine".

No brand of the transformers, possibly they are winded in-house?
 
If you buy any high power amp from China you need the knowledge and skill to test it yourself and to make modifications for safety and quality.
They are well known for low quality or minimum spec parts and poor construction.
Typical mains voltage will often push components past their limits, at worst this can result in a fire. (Happened to my 845 amp!)
You will also want to change the Chinese tubes for better quality so factor that into cost.
Sorry to be downbeat but these are things found by many owners.
 
You would need to define what you mean by quality. If it was just high fidelity sound reproduction you wanted then you might not be considering these amps anyway, as they appear to be aimed at a different market.

The specs, on paper at least, for the Muzishare & Cayin are pretty good

The Muzishare specs
Power: 30W RMS
THD: 1% (1kHz)
Frequency response: 15Hz ~ 35kHz (-1.5dB)
SNR: 92dB
Weight: 50kg


The Cayin's specs
Power: 24W RMS
THD: 0.3% (1 kHz)
Frequency Response: 10Hz - 26kHz, -3db
SNR: 90db
Weight: 38kg

Not sure whether a better SNR or THD is better for a lower noise floor coming through speakers & I'm clueless on which of their stated frequency response would give a more high fidelity sound.

Typical mains voltage will often push components past their limits, at worst this can result in a fire. (Happened to my 845 amp!)
You will also want to change the Chinese tubes for better quality so factor that into cost.


You guys are not making the decision to buy one easy lol.

Low quality Chinese tubes are a given, but the cost of quality 845 & 300B tubes are astronomical, to the point I would have to settle for Chinese tubes regardless. Otherwise the tubes themselves would cost as much as the amp.
As for a fire, well there seems to be a lot of Line Magnetic owners & I haven't seen one in flames (so far).
 
Chinese manufacturing

It feels like we tend to have a love hate relationship with Chinese audio products, and it is all too easy to knock Chinese goods based on the cheap tat that does get produced - but this is to satisfy Western demand for cheap tat.

Having recently looked at some old Mullard videos on YouTube - The Manufacture of Radio Valves - it is obvious that for the valves there are always going to be a lot of manual processes, and it is hard to imagine any other country than China being able to manage that type of high quality, skilled, labour intensive manufacturing.

I think we have a lot to thank China for, for making our hobby a lot more accessible, and for stimulating a greater interest in the sound of tubes, through affordable offerings, and hence driving the demand to ensure that most of the commonly used tubes are still in Production. Has it ever been more affordable to be a tube enthusiast, and what with hybrid designs, booster supplies, etc, have there ever been so many permutations of solution?

But with Hi-fi, there is a law of diminishing returns. As you head towards the more esoteric and specialist side, then quality costs, and the costs rise exponentially.

All of those amplifiers are competitively priced to gain a foothold in an efficient market. Perhaps with status symbols, the appearance and options can be used to mask poor quality, but there are generally reviews available to highlight shortcomings.

Are all of those amps for sale on AliExpress? Have you tried contacting the vendors with questions about the OPTs, passive components and tubes? Or maybe select the sturdiest option, with the aim to upgrade critical components at a later stage?

How good are your speakers? What is your music source?

My experience of buying better HiFi has been that the weakness of the remainder of my setup become all the more glaring, and even the music sources themselves can be lacking.
 
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