"Musmys C2860+" fully-balanced Preamplifier observation

[khaliss]

hi all,

I closely follow HiFi-Zone youtube channel, and having acquired a "clone" (Accuphase-inspired) power amp, the "E-406" & thoroughly impressed with it... convinced myself to also purchase the C-2860+ preamp & have a visually-matched deck combo set, as it received glowing reviews (video link) not only from him, but HiFi enthusiasts who follow his channel. I ordered almost 2 weeks ago & finally got it just last night... it sounds darn good out of the box, not even broken-in yet.

However, after measuring the SPL frequency response (left & right channels) using REW software, it seems to start roll-off at around 7-8Khz all the way down to 20Khz. Not sure if this is normal or my unit has an issue or needs to be broken in(?) My T8pro preamp does not have this issue... it's almost flat all the way to 20Khz. My source is a Topping E70 Velvet DAC, measurement results below. What do you guys think this preamp may just need some breaking-in period? The Aliexpress product page specs claim "Frequency characteristics: 20Hz~20KHZ (+0-0.15db)"

Will do more testing when I get home tonight, gonna try out the other output connectors (RCA & Balanced outs, it's got 2 sets of each) and see if this measurement is consistent. Thoughts?

LEFT channel:

RIGHT channel:

 

[DVDdoug]

Try a measurement with a direct electrical connection.

an issue or needs to be broken in(?)

Burn-in/break-in is a fallacy. Electronics should be stable and if it's not it's defective.

 

[khaliss]

Try a measurement with a direct electrical connection.


Burn-in/break-in is a fallacy. Electronics should be stable and if it's not it's defective.

ok, i'll look into doing that... essentially, that means measuring directly from the RCA output of the pre-amp, right?

 

[DVDdoug]

that means measuring directly from the RCA output of the pre-amp, right?

Right. But you'll need a regular soundcard (in a desktop/tower computer) or an audio interface with line inputs.

If the difference is real, that's pretty bad. Maybe something's wrong with the tone control circuit.

With a microphone, small changes in mic position or somebody moving in the room can make significant variations is the high frequency measurements. So hopefully it's not "real".

 

[khaliss]

I tested with the bypass switch ("Direct") on & off, which supposedly bypasses or engages tone controls... there was no difference in the frequency response graph.

 

[khaliss]

measured through line-out level (RCA), direct mode... bypassing tone controls.

results:

listening now for about an hour+ to tracks I'm really familiar with... it sounds so smooth, really darn good... I don't notice any loss in detail & sparkle. This is A/B back-to-back testing against the T8pro

 

[khaliss]

also my first in-room frequency response sweep test (done last night), I made a mistake of incorrectly setting the E70velvet DAC... did a factory reset and it looks like the dip starting from 8k all the 20khz has been somewhat fixed... it's still rolls off, but not as bad anymore

 

[Snoopy]

Don’t like these clone things. If I want a acuphase or Luxman I try to buy the real thing.

Who tells me that clone1 is the same as clone50 and they switch out some parts during production.
Or that not all the capacitors and things are not fakes .

 

[khaliss]

Ok, it was my mistake... the DAC wasn't actually set right LOL (the first measurements were wrong!). Here is the updated in-room (speaker) response graphs comparing both preamps:

In conclusion, the HF roll-offs aren't as bad as I initially thought... that was my mistake (incorrect setting on the DAC). But it does not take away from the fact that there is indeed a slow roll-off starting at around 8K and eventually about a 3db dip at 20Khz (from the Preamp's line-level output)

 

[khaliss]

Don’t like these clone things. If I want a acuphase or Luxman I try to buy the real thing.

Who tells me that clone1 is the same as clone50 and they switch out some parts during production.
Or that not all the capacitors and things are not fakes .

I totally get what you are saying... and I'd much rather have an original Accuphase or Luxman than a "clone", but there is no way I could afford HiFi gear that is at least 10 times the cost. I think these are not actual clones, since the components (capacitors, transistors, etc) are not the same, and the design I'm sure differs in many ways... I think they just use that term "clone" as a way to market these Chinese products for overseas buyers (who would not know what the brand "Musmys" is, for example).

For me, what's more important is that the product (either it be a "clone" or not) performs as what the manufacturer claims, and (of course) that they sound great.. ultimately presenting a hard-to-beat value proposition. In my case, their E-406 "clone" amp exceeded my expectations, and that's why I went for the C2860 preamp... which unfortunately falls a little short of the specifications from the manufacturer in terms of frequency response.

 

[Snoopy]

Yes if it works as intended and has great Value for the money there is no problem
Just doesn’t feel right with me. My biggest issue is really that nobody knows what you end up getting with these things.

 

[khaliss]

Yep, it's definitely a gamble... & I was willing to take it

 

[RayDunzl]

it sounds darn good out of the box, not even broken-in yet.
...

Thoughts?

How do you know it wasn't broken in yet?

 

[khaliss]

How do you know it wasn't broken in yet?

Well, isn't that what we would normally assume if a piece of audio equipment is brand new(?)