Focusrite Scarlett 2i2 Audio Interface Gen 3 Review

[amirm]

@amirm What is the analog source from which you supply the analog signal to the ADC input ? How pure is it ? Wondering if any distortion in the original input signal adds to the distortion showing on the ADC chart ?

As SIY mentioned, the APx555 that I have has a state-of-the-art analog waveform generator. Its distortion is essentially invisible in the dashboard view. See this video for how well it works:

 

[taudier]

I wish I had seen that earlier. RCA outputs and balanced outputs at that price is a really nice feature.

Maybe not. Into the Motu M2 manual it says : Line out Balanced, tip hot +16 dbu // RCA out +16 dbu. I guess it's impedance balanced, not truely balanced, but i don't know if it's important. I asked for the Focusrite Scarlett 2i2 3d and they said it was electronically-balanced.

 

[Music1969]

Hi @amirm

The manual of this model seems to suggest the line output supports BOTH balanced and unbalanced connection?

So a TS-to-RCA cable will work, for connecting to integrated amp unbalanced RCA input?

 

[Panelhead]

All professional gear with 1/4” output connectors is designed to use TRS connectors for balanced and TS connectors for single ended output. There is a buffering resistor in the (-) leg to prevent damage from the short circuit on the output. The S section on the plug touches both the (-) and ground.
BUT the recommended wiring for balanced to unbalanced cable is to use a TRS plug with a balanced cable and wire normally. Tip is connected to (+). Ring is connected to (-). The Shield is connected to the wire braid. At the RCA end the (+) is connected to the center pin. The (-) and braid are connected to the body of the RCA plug.

 

[LTig]

All professional gear with 1/4” output connectors is designed to use TRS connectors for balanced and TS connectors for single ended output. There is a buffering resistor in the (-) leg to prevent damage from the short circuit on the output. The S section on the plug touches both the (-) and ground.

Nope. You have to read the manual. RME states for the ADI-2 PRO fs that you should not plug a mono TRS connector into the stereo TRS plug because this shortcuts the (-) signal which may lead to higher distortion.

BUT the recommended wiring for balanced to unbalanced cable is to use a TRS plug with a balanced cable and wire normally. Tip is connected to (+). Ring is connected to (-). The Shield is connected to the wire braid. At the RCA end the (+) is connected to the center pin. The (-) and braid are connected to the body of the RCA plug.

This is exactly what you should not do with the RME since it shortcuts (-) to shield (ground). I would use a cable where the shield is left open at the RCA side.

 

[trl]

Tip is connected to (+). Ring is connected to (-). The Shield is connected to the wire braid. At the RCA end the (+) is connected to the center pin. The (-) and braid are connected to the body of the RCA plug.

I wouldn't touch the (-) to the GND, due to short-circuit. I would simply leave (-) not connected and just use the (+) and GND to connect to the RCA plug.

P.S.: For input stage of ADC the (-) should indeed be connected to GND (in a RCA to TRS adapter).

 

[dfuller]

I feel I should mention that the line level input is just the mic preamp padded way, way down. That's probably why the performance is so poor. On an subjective level, the mic preamps in these don't sound particularly good in my experience (subjective, of course). They say the design is transparent but... eh, not really, at least not in my experience. There's a distinct mid hump compared to something flatter like a TI PGA2500.


Anyway, for those talking about headphones a couple pages ago, I feel that people miss that speaker voice coils are inductive loads and have a big spike in impedance around the resonant frequency.

 

[Blumlein 88]

I feel I should mention that the line level input is just the mic preamp padded way, way down. That's probably why the performance is so poor. On an subjective level, the mic preamps in these don't sound particularly good in my experience (subjective, of course). They say the design is transparent but... eh, not really, at least not in my experience. There's a distinct mid hump compared to something flatter like a TI PGA2500.


Anyway, for those talking about headphones a couple pages ago, I feel that people miss that speaker voice coils are inductive loads and have a big spike in impedance around the resonant frequency.

Padding down the mic input is pretty much the way it is done in most interfaces until you get into more expensive devices. That alone doesn't prevent them from having good line level performance.

 

[scott wurcer]

I feel I should mention that the line level input is just the mic preamp padded way, way down. That's probably why the performance is so poor. On an subjective level, the mic preamps in these don't sound particularly good in my experience (subjective, of course). They say the design is transparent but... eh, not really, at least not in my experience. There's a distinct mid hump compared to something flatter like a TI PGA2500.

Subjective is the key word, how can you say flatter when they both have flat frequency response as measured.

 

[Music1969]

I wouldn't touch the (-) to the GND, due to short-circuit. I would simply leave (-) not connected and just use the (+) and GND to connect to the RCA plug.

P.S.: For input stage of ADC the (-) should indeed be connected to GND (in a RCA to TRS adapter).

Thanks guys.

Will this Mogami TS-to-RCA cable automaticallyy work with this Focusrite unit, connecting to unbalanced RCA input of integrated amp?

http://www.mogamicable.com/category/products/gold_TS-RCA_6_12.php

Safe? No risk of short circuit? @Panelhead @LTig @trl

 

[trl]

I would recommend Fig. 1 from page 9 from here: https://www.hollandlink.eu/VandenHul-Wiring Diagrams.pdf.

 

[Music1969]

I would recommend Fig. 1 from page 9 from here: https://www.hollandlink.eu/VandenHul-Wiring Diagrams.pdf.

View attachment 66704​

Thanks i'll send this to Mogami to clarify their TS-to-RCA cable for me, when using with the Focusrite unbalanced output.

Since it's a TS connector that Mogami use, there should be no way to wire it to risk a short circuit, I assume?

http://www.mogamicable.com/category/products/gold_TS-RCA_6_12.php

 

[LTig]

Thanks guys.

Will this Mogami TS-to-RCA cable automaticallyy work with this Focusrite unit, connecting to unbalanced RCA input of integrated amp?

http://www.mogamicable.com/category/products/gold_TS-RCA_6_12.php

Safe? No risk of short circuit? @Panelhead @LTig @trl

No. The shortcut occurs at the mono TRS connector: (-) and shield are one piece of metal.

 

[Music1969]

No. The shortcut occurs at the mono TRS connector: (-) and shield are one piece of metal.

Mogami's reply regarding that Van Den Hul image:

"Their drawing shows the ring completely exterminated. I do not usually leave a connection open that way unless the equipment insisted. Industry standard is to ground (short) the ring connection rather than leave it open. Using a TS to RCA would do the same thing."

 

[trl]

"Their drawing shows the ring completely exterminated. I do not usually leave a connection open that way unless the equipment insisted. Industry standard is to ground (short) the ring connection rather than leave it open. Using a TS to RCA would do the same thing."

This is useful when you need an unbalanced to balanced connection, but vice-versa the short-circuit between (-) and GND will cause overheating the output opamp and perhaps the series resistors, if any. Feel free to read http://www.ians-net.co.uk/articles/balanced_lines.php for a brief explanation of the process of converting the signal from balanced to unbalanced (https://www.jhbrandt.net/wp-content...tion_of_Balanced_and-Unbalanced-Equipment.pdf is more detailed).

Such TRS-to-RCA may not exist on the market, so either you will DIY, either you will buy dedicated equipment/adapters like:
https://www.cs1.net/products/jensen_transformers/PC-2XR.htm
https://www.canford.co.uk/Products/...-Passive-balanced-XLR-to-unbalanced-RCA-phono
https://www.newark.com/mcm-custom-audio/555-8485/balanced-unbalanced-line-level/dp/12M5508

 

[Music1969]

Such TRS-to-RCA may not exist on the market

Hi, thanks for all the info but I'm confused why TRS-to-RCA would be needed when the Focusrite supports TS unbalanced output (screenshot from manual below) and there exists TS-to-RCA cables, like the Mogami I linked.

Apologies in advance if this is a stupid question, but am I missing something very obvious here?

http://www.mogamicable.com/category/products/gold_TS-RCA_6_12.php

 

[dfuller]

Subjective is the key word, how can you say flatter when they both have flat frequency response as measured.

That's what I don't know. They should, by all measurements, sound the same. There's no reason they should be any different, and yet they are.

Padding down the mic input is pretty much the way it is done in most interfaces until you get into more expensive devices. That alone doesn't prevent them from having good line level performance.

Quite true, though I have to wonder if in this case there's something else going on that's markedly increasing distortion...

 

[boXem]

Nope. You have to read the manual. RME states for the ADI-2 PRO fs that you should not plug a mono TRS connector into the stereo TRS plug because this shortcuts the (-) signal which may lead to higher distortion.

This is exactly what you should not do with the RME since it shortcuts (-) to shield (ground). I would use a cable where the shield is left open at the RCA side.

Same thing for the Motu Mx, THD increases by about 30 dB

 

[trl]

Hi, thanks for all the info but I'm confused why TRS-to-RCA would be needed when the Focusrite supports TS unbalanced output (screenshot from manual below) and there exists TS-to-RCA cables, like the Mogami I linked.

Apologies in advance if this is a stupid question, but am I missing something very obvious here?

http://www.mogamicable.com/category/products/gold_TS-RCA_6_12.php


View attachment 66749

I'm sure you can connect TS as well, but please read the links I have posted in my previous message when you have some time.

Also, same manual states "we highly recommend using balanced cables to connect these to the outputs of the Scarlett 2i2".

 

[scott wurcer]

No. The shortcut occurs at the mono TRS connector: (-) and shield are one piece of metal.

Nice that someone points this out. Most of the balanced to unbalanced adapters use a transformer, that way you have the full benefit of the balanced cable and little loss of signal power. Assuming something like a dual op-amp making a low impedance balanced out shorting one side to ground would short one side and likely effect the other side in some way.