SMSL SP400 Review (headphone amp)

[mrjayviper]

is the top glass or scrached-prone acrylic/perspex?

 

[mrjayviper]

I would have to dig up my infrared thermometer to be sure but just by touch I would say my Topping A30Pro gets hotter than my Audio-GD NFB-11.38

Don't know what your situation is but I can't imagine my Topping nor Audio-GD being any influence on my room temperature..

I was thinking of getting the big combo (Master 11 or D27/R27)

(I just checked the NFB 11.38 and the transformer on that thing is tiny compared to the D27s (which has 3 transformers))

 

[Jimster480]

I was thinking of getting the big combo (Master 11 or D27/R27)

(I just checked the NFB 11.38 and the transformer on that thing is tiny compared to the D27s (which has 3 transformers))

Don't waste a cent on audioGD. It is a total sham of a company.

 

[mrjayviper]

Don't waste a cent on audioGD. It is a total sham of a company.

I was blinded by the interior pics!

 

[Veri]

I was blinded by the interior pics!

They stuff it full with b-brand capacitors, don't be too impressed

 

[Snoopy]

is the top glass or scrached-prone acrylic/perspex?

Plastic

 

[Jimster480]

I was blinded by the interior pics!

They have so much b-roll of their interior with fancy looking layouts. However many of the actual components are cheaper versions of the real stuff that delivers quality where it counts.

 

[mrjayviper]

output impedance of the device? thanks

In asking that, I seemed to recall seeing a graph of output impedance on on past reviews which is absent on recent reviews.

Found an old review with output impedance graph: https://www.audiosciencereview.com/...asurements-of-gustard-h20-headphone-amp.7402/

 

[Lupin]

They have so much b-roll of their interior with fancy looking layouts. However many of the actual components are cheaper versions of the real stuff that delivers quality where it counts.

So be it but my NFB-11.38 outlived my SMSL DAC for over a year now and counting..

 

[v1adpetrov2]

Wouldn't it need 16+ relays for 256 levels for 4 channels (+L,-L,+R,-R)? This only has two more relays than the SH-9, which I understand the extra 2 relays are for the preamp function.

You are absolutely right!
Everyone has seen photos of the SH-9 and SP400 circuits, but no one except you found it difficult to analyze what was under their noses.

In the SP400, the signal input circuit is completely identical to the circuit in the SH-9.
So input XLR-balanced signal is converted to unbalanced - only the hot-L, hot-R and GND signals are selected (the cold-L and cold-R signals are ignored).
And only then gets to the 256 level relay volume control, which consists of eight relays for adjusting +L and +R from RCA/XLR inputs.
Then, after the volume control, the unbalanced signal again is converted into a balanced one and goes to the headphone amplifier and XLR outputs.
By the way, Topping Pre90 has the same detrimental scheme.

The number of relays required to adjust the volume of the balanced signal (four channels) was halved to the two channels for the sake of economy and easy deception of consumers.
I.e., the SP400 is NOT a "fully balanced" amplifier from a technical point of view.

P.S. For example, the GUSTARD H16 amplifier has 12 relays with 64 levels of volume control to the four channels of a real balanced signal from XLR connectors.

 

[Roland68]

You are absolutely right!
Everyone has seen photos of the SH-9 and SP400 circuits, but no one except you found it difficult to analyze what was under their noses.
View attachment 249806 View attachment 249807
In the SP400, the signal input circuit is completely identical to the circuit in the SH-9.
So input XLR-balanced signal is converted to unbalanced - only the hot-L, hot-R and GND signals are selected (the cold-L and cold-R signals are ignored).
And only then gets to the 256 level relay volume control, which consists of eight relays for adjusting +L and +R from RCA/XLR inputs.
Then, after the volume control, the unbalanced signal again is converted into a balanced one and goes to the headphone amplifier and XLR outputs.
By the way, Topping Pre90 has the same detrimental scheme.
View attachment 249907
The number of relays required to adjust the volume of the balanced signal (four channels) was halved to the two channels for the sake of economy and easy deception of consumers.
I.e., the SP400 is NOT a "fully balanced" amplifier from a technical point of view.

P.S. For example, the GUSTARD H16 amplifier has 12 relays with 64 levels of volume control to the four channels of a real balanced signal from XLR connectors.
View attachment 249809

It is perfectly normal for the balanced signals to be debalanced after the input and rebalanced after the volume control, before the amplifier stage. This has been done for tens of years and is the case even with many devices costing several thousand dollars.
Few devices are fully and consistently balanced.
To see that, you just have to pay attention to whether the volume control has 2 or 4 channels. So stereo vs. quad potentiometer, 2-channel or 4-channel chip on the volume control, 6-8 relays or 12-16 relays, etc.

How useful is a symmetrical small signal processing within a device?
I assume that it is clear why a symmetrical small signal transmission with cables makes sense and how the elimination of interference works.
What happens to the balanced signal if the components in the +/- signal path are not 100% the same? This applies to resistors, transistors, coupling capacitors, OPAmps, etc.
Note that all non-complementary signal components will be deleted at the end.

 

[Xaviedie]

quality rca cable to connect it to this SP400? (rca/jack & rca/rca)

for smartphone LG G7 ThinQ (or other..)

What quality dac do you recommend for connecting to this SP400 amp, to pc

 

[Roland68]

quality rca cable to connect it to this SP400? (rca/jack & rca/rca)

for smartphone LG G7 ThinQ (or other..)

What quality dac do you recommend for connecting to this SP400 amp, to pc

Can you solder your cables yourself?

See if you can still get a Sabaj A20d (balanced) or A10d (unbalanced, both old versions, not 2022) for less than $200 on Amazon, Hifi-Express, etc. You will hardly find a better price/performance ratio.

 

[Xaviedie]

Can you solder your cables yourself?

See if you can still get a Sabaj A20d (balanced) or A10d (unbalanced, both old versions, not 2022) for less than $200 on Amazon, Hifi-Express, etc. You will find it hard to find better value for money.

no i don't know how to weld

OK, thanks lot

 

[Xaviedie]

Pouvez-vous souder vos câbles vous-même ?

Voyez si vous pouvez toujours obtenir un Sabaj A20d (équilibré) ou A10d (asymétrique, les deux anciennes versions, pas 2022) pour moins de 200 $ sur Amazon, Hifi-Express, etc. Vous trouverez difficilement un meilleur rapport prix/performance.

Sorry for my english, i m french and i use google traduction

Sabaj A20d is a dac, not an rca cable.. I want a quality rca cable (rca/jack end)

if I am wrong please tell me the cable by a web address link

 

[Roland68]

no i don't know how to weld

OK, thanks lot

Look for ready-made Sommer Cable, Mogami or Gotham cable. Assembled these should be under $50 (for short lengths).
As an an example:
Sommer Cable RCA/3.5mm

 

[Roland68]

Sorry for my english, i m french and i use google traduction

Sabaj A20d is a dac, not an rca cable.. I want a quality rca cable (rca/jack end)

if I am wrong please tell me the cable by a web address link

The recommended DACs were the answer to your question... "What quality dac do you recommend for connecting to this SP400 amp, to pc"

If you are from France then audiophonics and Amazon are good places to go for cables.
As I said, assembled cables from Sommercable, Mogami or Gotham.
Cheap cable
summercable

 

[Veri]

World Best Cables on Amazon(.de other otherwise)!

 

[BenF]

World Best Cables on Amazon(.de other otherwise)!

They're expensive! I'm usually going for Cordial cables (on amazon).

 

[Xaviedie]

They're expensive! I'm usually going for Cordial cables (on amazon).

cordial, known in the world of the studio