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SMSL SP200: Do We Get Golden Samples For Review?

Labjr

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#61
My 25 year old tube preamp has a Penny & Giles pot that cost about $400 at the time. As good as it is, I'm pretty sure it doesn't track as well or sound as good as a stepped attenuator would.

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Toku

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#62
Some datasheet specs to put this in context:
Alps RK27 series - £8.78 each at 500+ quantities, Gang error <3dB 0 to -60dB, <5db -60dB to -80dB
Bourns PTD90 series - £0.92 each at 500+ quantities, Gang error <3dB 0 to -40dB, unspecified at greater attenuation
Even the 'poor' performance of this unit is within the spec of a standard high quality pot range. Manufacturers would need to test the pots if they wanted a tighter match - not unprecedented, but probably uncommon at this price point.

Also note the lack of standard for taper letter designations - for Bourns the A[1-6] series are log tapers, while the B series are symmetrical about the centre point. Vishay do something else entirely.
Although it is a little expensive, the following POT is recommended if sound quality is important.
It is also sold at Amazon in Japan.
Of course, Taper-A is used for volume control.
However, the pin arrangement is the same, but the size needs to be checked.

CP600 (Potentiometer)
http://www.tkd-corp.com/products/pot/potentiometer.html#cp600

When I examined it in detail, it seems that it cannot be installed unless it is BOURNS PTD90 Series.
Looking at the photo of the SP200 main board, it seems that the volume POT is not directly attached to the main board, but is attached to the main board after being attached to a small board.
 

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somebodyelse

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#63
Although it is a little expensive, the following POT is recommended if sound quality is important.
It is also sold at Amazon in Japan.
Of course, Taper-A is used for volume control.
However, the pin arrangement is the same, but the size needs to be checked.

CP600 (Potentiometer)
http://www.tkd-corp.com/products/pot/potentiometer.html#cp600
And still only matched to 3dB (over 150 degrees of 300 operating angle - how many dB is that?). The point was that the 3db matching between pots is pretty much standard for off the shelf components, extending to higher attenuations for the better ones. To guarantee better matching you (or the manufacturer) need either a special order for better matched pots, or a testing process to select the better matched pots from a load of them. Or avoid pots.
 

Jumbotron

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#64
Yesterday I received my unit. Purchased from SMSL's official store in Aliexpress and received in Spain just in five days or so since shipment. Nice surprise.

I have just tried it for the first time with some music. Volume pot set to middle way/central position. Channel balance is perfect to my ears and there is plenty of power indeed, especially as I was coming from a portable Fiio E12 Mont Blanc.
 

solderdude

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#65
sound as good as a stepped attenuator would.
How can a potmeter impart a certain sound ?

I am sure there are some non-linearities but do not expect them to come anywhere near audible thresholds in any case.

Just curious where I can find measurements of this... I mean even the very cheap pot in the Geshelli doesn't even seem to have a sound signature.
 

mkawa

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#66
wiper pots do induce noise, but high quality pots induce very little. channel imbalance is present in any pot though, and varies with rotation and even over multiple trials, even in top of the line pots like the "blue velvet" alps rk27

also for those calling for stepped atten, a DACT costs as much as this amp, and it's larger than an rk27. something like a gilmore/headamp flagship with a dact goes for more like 1-2k$ than 250$.
 

solderdude

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#67
Yes, of course there is a difference in tracking/channel balance, taper accuracy, noise while adjusting, tactile feel, longevity, size, shielding, mechanical stability etc.
But the my question is how it can possibly SOUND different.
To change the sound the signal would have to deviate in other ways than merely amplitude at levels large enough to become audible.
 
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#68
Yes, of course there is a difference in tracking/channel balance, taper accuracy, noise while adjusting, tactile feel, longevity, size, shielding, mechanical stability etc.
But the my question is how it can possibly SOUND different.
To change the sound the signal would have to deviate in other ways than merely amplitude at levels large enough to become audible.
Wouldn't it actually be easy to check if amps/dac/pots change the sound in a headphone, for example by getting a dummy head with very accurate pinna coupled with high resolution in-ear microphones in a anechoic chamber to check if what comes out of the headphone changes, ideally without moving the actual positioning of the headphone/dummy head as that would change the measurements, i wonder why no one has done this yet, or maybe they have but i just can't find it.
 

solderdude

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#69
Wouldn't it actually be easy to check if amps/dac/pots change the sound in a headphone, for example by getting a dummy head with very accurate pinna coupled with high resolution in-ear microphones in a anechoic chamber to check if what comes out of the headphone changes, ideally without moving the actual positioning of the headphone/dummy head as that would change the measurements, i wonder why no one has done this yet, or maybe they have but i just can't find it.
The reason why nobody has done this yet to prove a potmeter has a sound signature is because you cannot possibly get any meaningful results this way.

It's like asking Machete to make some pencil art for you.
 

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