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Can a experienced DIYer tell the quality of a 845 amp by looking at the internals?
Can a experienced DIYer tell the quality of a 845 amp by looking at the internals?
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Old 22nd July 2019, 12:42 AM   #1
Dude with a Tube is offline Dude with a Tube
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Question Can a experienced DIYer tell the quality of a 845 amp by looking at the internals?

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
Click the image to open in full size.


Cayin $4k 845 amp
Click the image to open in full size.


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


Line Magnetic 518ia $3k
Click the image to open in full size.


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
Click the image to open in full size.

And the cheapest of all 845 amps I found.
LaoChen 845 tube amp at $1,000!
Click the image to open in full size.
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?
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Old 22nd July 2019, 12:59 AM   #2
ogie is offline ogie  United States
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Can a experienced DIYer tell the quality of a 845 amp by looking at the internals?
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.
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Old 22nd July 2019, 01:51 AM   #3
Bigun is offline Bigun  Canada
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Can a experienced DIYer tell the quality of a 845 amp by looking at the internals?
I also read some good reviews of the Line Magnetic. If I didn't want to DIY my own amp I'd be quite willing to purchase one from these guys myself. The internals look decent enough to me.
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Old 22nd July 2019, 08:15 AM   #4
Dude with a Tube is offline Dude with a Tube
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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?
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Old 22nd July 2019, 08:51 AM   #5
K.A.B is offline K.A.B  Sweden
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Anyone can build an amplifier with expensive components without using good topology on the circuit diagram but it is still a bad amplifier.

Anders
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Old 22nd July 2019, 09:37 AM   #6
DF96 is offline DF96  England
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Quote:
Can a experienced DIYer tell the quality of a 845 amp by looking at the internals?
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.
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Old 22nd July 2019, 06:33 PM   #7
ColinA123 is offline ColinA123  United Kingdom
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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.
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Old 22nd July 2019, 06:39 PM   #8
dhaen is offline dhaen  Europe
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Old 22nd July 2019, 09:33 PM   #9
Dude with a Tube is offline Dude with a Tube
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Quote:
Originally Posted by DF96 View Post
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.

Quote:
Originally Posted by ColinA123 View Post
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.
Quote:
Originally Posted by dhaen View Post
No.
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).
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Old 23rd July 2019, 09:53 AM   #10
Kay Pirinha is offline Kay Pirinha  Germany
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As said yet, these amps appear to be well put together. But can we be sure that all these bling-bling components are genuine ones, not fakes? I'd be very worried about anything with »China« on it's label.
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