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Focusrite Clarett 2Pre USB - Tear down, bit of internal analysis and few in-house measurements

trl

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While waiting for my Motu M4 interface to arrive from Thomann, I was puzzled by a change in the estimated time delivery for the new orders on this product. As my ETA was estimated initially to about 5 weeks, when I saw that for the new orders the ETA changed to 12-17 weeks, I thought that my order will be affected too, so I told Thomann that I want to cancel my order, then I purchased an used Clarett 2Pre USB instead. However, Thomann told me that my order is on a different batch, so I should be able to receive it in a week or so, so I haven’t cancelled in the end, so now I have both M4 and Clarett 2Pre. :)

This Clarett had an issue with analogue #2 input, its gain being exactly 8 dB lower than stated on the specs, so mics like AKG D5 or Shure SM7B could not be used with that input. I sent it in RMA and the authorized seller was able to resolve it (apparently potentiometer or the plug from pot's cables was not perfectly soldered on the board).

However, manufacturer full specs can be found here: https://focusrite.com/en/usb-c-audio-interface/clarett-usb/clarett-2pre-usb and datasheet here https://fael-downloads-prod.focusri...oads/32407/clarett-2preusb-user-guidev1.2.pdf. Below a screenshot from the datasheet with the performance specs:

Clarett2Pre_specs.png

The Focusrite Control, the actual control panel from where we can choose how to route audio signals between inputs and outputs, is explained in detail here: https://support.focusrite.com/hc/en-gb/articles/115004431669. It is rather hard to understand all the features in few minutes, but after playing around a bit things got easier to catch.

Clarett2PreUSB_Control_interface.png


The interface is very well built, the aluminum case is very thick (like 2-2.5mm) and heavy, it could be used as heatsink for power-amp transistors. The look is similar with other Focusrite interfaces, just a bit more shiny-red. Front XLR mic plugs are made by Amphenol and the mics are a bit hard to plug, but the final connection is sturdy and there's no way to unplug a mic without using both hands (actually this is a Pro not a Con, as we don't want mics to have a lose connection with the interface).

Hard to disassemble, but totally worth the challenge and time spent, as the shiny case is hiding three boards with complex electronics inside.

IMG_0812 copy.jpg

Clarett 2Pre main board, bottom view


IMG_0749 copy.jpg

Clarett 2Pre main board, top view

USB and TOSLINK/ADAT transport card is build around couple of XMOS chips marked as XFR002C and XFR001C. They’re powered by dedicated power regulators across the same transport board.

IMG_0751 copy.jpg

USB transport board - top view

The +12 V coming from the external power brick gets lowered to +5 V and to +3.3 V via NCP3170 PWM switching converters. Digital components are using these low-voltage power rails, but also relays too, while the analogue audio chips are expecting a higher voltage.

IMG_0819 copy.jpg

NCP3170 buck converters

Few M3425 3A boost converters have been seen on the main board. These are boosting existing +5V rail to a higher voltage to power the audio circuitry, so the output power to be higher. This way the built-in headphones amplifier will be able to drive more headphones. For example, the dual opamps from the board (JRC 4556/5532/8065, OPA 2141) are power by +/-9.5 V rails, so a total of about 19 V RMS, even if the audio interface is only powered from the USB + 5 V. However, if the USB port where Clarett is connected is unable to sustain 3 A (a total output power of 15 W), then a LED will blink, making impossible the usage of the interface without the external power adapter.

IMG_8938 copy_.jpg

MP3425 boost converter

Electrolytic capacitors used on the board are mostly CapXon KM series series, Jamicon SS and Jamicon SK series, but also few Nichicon PM series too. Temperature inside the Clarett is not high at all, the outer case is barely warm after hours of continuous operation, so caps temperature rating should not matter here.

IMG_0760.jpg

Main board capacitors


The DAC chip inside is an AKM AK4413EQ 120dB S/N, 24-Bit 192kHz 4ch DAC, a rather obsolete part these days, not to be used for new designs, but still with a respectable THD+N of -104 dB.

The ADC chip is an AKM AK5388AEQ, 120dB S/N, 24-bit 192kHz 4ch ADC, obsolete part as well, but with a very good THD+N of -100 dB.

IMG_0817 copy.jpg

ADC and DAC chips


ADC inputs seem to be buffered by NJM8065 dual opamps, while DAC outputs seem to be buffered by JRC5532 opamps, probably one dual opamp for each ADC input and for each TRS output as well.

Analogue inputs gain is done by couple of THAT 1583 chip, a Low-Noise Differential Audio Preamplifier, able to deliver a 60 dB gain with only -128.9dBu (1.9 nV/√Hz) EIN of noise. Its THD+N is 0.0006% @ 0 dB gain, 0.001% @ 40 dB gain and 0.006% @ 60 dB gain, respectable figures for an analogue input of a home studio interface.

IMG_0816 copy.jpg

Two such THAT 1583 chips are controlling the gain for the two analogue inputs


A similar THAT preamp is also used inside the Motu M4, the THAT 6263. A quick compare of THAT preamps can be found below:

THAT_preamps.png

THAT digitally controlled preamps


The built-in headphones amplifier is powerful enough for a studio interface, definitely more powerful than Focusrite Solo Gen3 or Motu M4. It is based on the Japanese operation amplifier NJM4556AL, same as used as output buffer in Objective 2 headamp (just one single opamp, not couple of them, like in Objective 2). Theoretically, according to the datasheet, powered at +/-9.5 V it should be able to push up to 5.3 V RMS into high impedance headphones, approaching it’s 70 mA current limitations when pushed to low impedance cans. I was able to listen comfortable to my 40 Ohms Hifiman HE-560 planar headphones, which was not possible with Motu M4 due to the distortion when pushing up the volume, so there's enough juice on the 6.3 mm jack.


IMG_0748.jpg

I was using 120 dB 16 Ohms sensitive IEMs and the background noise was there, but very low intensity, about the same as on Motu M4, totally not interfering with the music or audio tracks playing. The power before clipping on headphones would be about:
  • 180 mW / 30 Ohms (about 7 times higher than the M4)
  • 210 mW / 40 Ohms
  • 200 mW / 100 Ohms
  • 75 mW / 300 Ohms
  • 38 mW / 600 Ohms.

Clarett_headamp_300_Ohms_copy.png

Clarett headamp - 4.7 V / 600 Ohms (pretty much as advertised by manufacturer: +16 dBu, which means 4.88 V RMS)


Clarett_headamp_30_Ohms_copy.png

Clarett headamp - 2.45 V / 30 Ohms (top half clipping, but dropping voltage to 2.3-2.35 V makes the sine perfect again)

I can spot on the board one OPA2141 dual opamp followed by couple of JRC8065 opamps, but unfortunately I am not sure what they do, although I have a feeling that the two JRC8065 are summing up two balanced channels into two single-ended ones, then the OPA2141 might act as a gain stage for the JRC4556 headphones buffer, but I’m unable to prove that, as the PCB is quite opaque. However, this OPA2141 is the best performer from all opamps from the board, just not sure what is its purpose on the board.

The front panel/board has LEDs and potentiometers. I can spot three HC595AG 8−Bit Serial Shift Register with Latched 3−State Outputs. most likely to control the front lights, based on device state (INST, AIR, 48V etc.). I’ve also seen at least three more such shift registers on the main board.

IMG_0753.jpg

Frontal board, with potentiometers and controls


The four potentiometers from this board are very similar with ALPHA RD902F-40-00D series, the one from headphone being probably logarithmic, while the other three probably being linear carbon tapers. Some Focusrite users seem to have troubles with such pots, same applies to ASUS Essence One users that are sharing similar APLHA pots, but time will tell how long will resist. One thing’s for sure, replacing them is quite difficult, because it involves a complicated way to dismantle the device, get out the boards and to then to unsolder double-sided soldered pins. Hope I’ll never have issues with these pots.


IMG_0752.jpg

Frontal board, with potentiometers and controls

L.E.: Worth adding that the only analogue volume control is for the headphones output, while the other three potentiometers (for gain and master volume) are all digitally controlled.
 
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trl

trl

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Below are couple of measurements done with Motu M4 on the headphones jack plug of Clarett 2Pre USB, no headphones connected. Due to a strange behavior caused by the loopback, I couldn't measure the Clarett's headamp with Clarett's analogue inputs, so I did this with the M4.

Clarett2PreHeadamp_THD_2V-measured_on_MotuM4_Line3.png

Clarett 2Pre USB - Headphones amplifier measured with Motu M4, THD @ 2V RMS, no headphones connected

Clarett2PreHeadamp_60Hz-7KHz_2V-measured_on_MotuM4_Line3.png

Clarett2Pre Headamp - 60Hz & 7 kHz @ 2 V RMS, measured on Motu M4 Line3

Clarett2PreHeadamp_1KHz_2V-measured_on_MotuM4_Line3.png

Clarett2Pre Headamp - 1 kHz @ 2 V RMS, measured on Motu M4 Line3

Clarett2PreHeadampHE560_1KHz_1V-measured_on_MotuM4_Line3.png

Clarett 2Pre Headamp driving HE-560, 1KHz sine @ 1 V RMS, measured on Motu M4 Line3

Clarett2PreHeadampHE560_1KHz_2V-measured_on_MotuM4_Line3.png

Clarett 2Pre Headamp driving HE-560, 1KHz sine @ 2 V RMS, measured on Motu M4 Line3


Below are some ARTA measurements done on the output TRS plugs, Clarett 2Pre in loopback with the Line In from front panel. Due to the digital's 1 dB volume resolution it was impossible for me to achieve the perfect 1 V, 2 V and 4 V output levels:

Clarett2Pre_LineInput2_1.1V.png

Clarett 2Pre - Line Input #2, 1.1 V RMS, 1 kHz sine

Clarett2Pre_LineInput2_2.1V.png

Clarett 2Pre - Line Input #2, 2.1 V RMS, 1 kHz sine

Clarett2Pre_LineInput2_3.02V.png

Clarett 2Pre - Line Input #2, 3.02 V RMS, 1 kHz sine

Clarett2Pre_LineInput2_4.34.V.png

Clarett 2Pre - Line Input #2, 4.34 V RMS, 1 kHz sine

For a side-by-side compare, below are couple of measurements done for the M4's DAC line-outs:

MotuM4_to_Clarett2Pre_LineInput2_2.11.V.png

MotuM4 to Clarett 2Pre Line Input #2, 2.11 V RMS sine
MotuM4_to_Clarett2Pre_LineInput2_4.34.V.png

MotuM4 to Clarett 2Pre Line Input #2, 4.34 V RMS sine


We can notice the elevated noise shaping above 2 kHz on the M4 vs. the Clarett, causing the THD+N on the M4 to be inferior to Clarett on 2 V sines, while on the 4 V sines it seems to be a bit better than Clarett.

Couple of RMAA test results too, first done on 2 V RMS, but the second on 3.85 V RMS (due to the digital volume control I needed to choose between 3.85 V and 4.34 V and I was choosing the one more close to 4 V RMS).

ASIO - Focusrite Clarett 2V.png

ASIO, RMAA - Focusrite Clarett 2Pre loopback @ 2V.png


ASIO - Focusrite Clarett 3.85V.png

ASIO, RMAA - Focusrite Clarett 2Pre loopback @ 3.85V.png

A nice set of measurements was recently done by @coastpunk here: https://www.audiosciencereview.com/...te-clarett-2pre-usb-quick-measurements.10576/.

L.E.: In case you haven't noticed, Focusrite is advertising this interface as having 10 inputs, while there are only 2 XLR input plugs for connecting mics or Line level devices. Although this is technically correct, due to 8 ADAT inputs when a dedicated adapter is attached to the TOSLINK input plug, I think it would be easier for everyone to understand how many inputs this interface actually has:
- Analogue XLR inputs: 2
- Line level TRS inputs (combined with XLR plugs): 2
- TOSLINK input: 1
- MIDI input: 1
- ADAT inputs: 8
Hope the above helps.
 
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trl

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As I'm not comfortable with what I see here I upload below THD+N measurements on the Clarett 2Pre USB's jack @ 2V RMS:

Clarett2PreHeadamp_THD+N_2V-measured_on_MotuM4_Line3.png


Clarett2PreHeadamp_THD_2V-measured_on_MotuM4_Line3.png

2 V RMS @ 300 Ohms means about 13 mW. On Julien's graph 13 mW corresponds to a THD+N of about -70 dB, while on my graph the THD (not THD+N) is mostly below -110 dB. If the potentiometer was at max. on Julien's measurements and the volume was modulated from the input source, then the noise might have a big influence on the output THD+N, but when performing measurements on headphones output of an analogue controlled output stage we need to make use of the potentiometer to adjust the output power.
 

telecode101

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Great work. Can I ask, now many gen of Clarett are there? 2 from what I can gather. The original Thunderbolt and the new USB. Is there are indication there there will be a gen 3 released?

I am researching upgrading to a Clarett at this point.
 

umbral

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While waiting for my Motu M4 interface to arrive from Thomann, I was puzzled by a change in the estimated time delivery for the new orders on this product. As my ETA was estimated initially to about 5 weeks, when I saw that for the new orders the ETA changed to 12-17 weeks, I thought that my order will be affected too, so I told Thomann that I want to cancel my order, then I purchased an used Clarett 2Pre USB instead. However, Thomann told me that my order is on a different batch, so I should be able to receive it in a week or so, so I haven’t cancelled in the end, so now I have both M4 and Clarett 2Pre. :)

This Clarett had an issue with analogue #2 input, its gain being exactly 8 dB lower than stated on the specs, so mics like AKG D5 or Shure SM7B could not be used with that input. I sent it in RMA and the authorized seller was able to resolve it (apparently potentiometer or the plug from pot's cables was not perfectly soldered on the board).

However, manufacturer full specs can be found here: https://focusrite.com/en/usb-c-audio-interface/clarett-usb/clarett-2pre-usb and datasheet here https://fael-downloads-prod.focusri...oads/32407/clarett-2preusb-user-guidev1.2.pdf. Below a screenshot from the datasheet with the performance specs:


The Focusrite Control, the actual control panel from where we can choose how to route audio signals between inputs and outputs, is explained in detail here: https://support.focusrite.com/hc/en-gb/articles/115004431669. It is rather hard to understand all the features in few minutes, but after playing around a bit things got easier to catch.



The interface is very well built, the aluminum case is very thick (like 2-2.5mm) and heavy, it could be used as heatsink for power-amp transistors. The look is similar with other Focusrite interfaces, just a bit more shiny-red. Front XLR mic plugs are made by Amphenol and the mics are a bit hard to plug, but the final connection is sturdy and there's no way to unplug a mic without using both hands (actually this is a Pro not a Con, as we don't want mics to have a lose connection with the interface).

Hard to disassemble, but totally worth the challenge and time spent, as the shiny case is hiding three boards with complex electronics inside.

View attachment 100528
Clarett 2Pre main board, bottom view


View attachment 100529
Clarett 2Pre main board, top view

USB and TOSLINK/ADAT transport card is build around couple of XMOS chips marked as XFR002C and XFR001C. They’re powered by dedicated power regulators across the same transport board.

View attachment 100530
USB transport board - top view

The +12 V coming from the external power brick gets lowered to +5 V and to +3.3 V via NCP3170 PWM switching converters. Digital components are using these low-voltage power rails, but also relays too, while the analogue audio chips are expecting a higher voltage.

View attachment 100533
NCP3170 buck converters

Few M3425 3A boost converters have been seen on the main board. These are boosting existing +5V rail to a higher voltage to power the audio circuitry, so the output power to be higher. This way the built-in headphones amplifier will be able to drive more headphones. For example, the dual opamps from the board (JRC 4556/5532/8065, OPA 2141) are power by +/-9.5 V rails, so a total of about 19 V RMS, even if the audio interface is only powered from the USB + 5 V. However, if the USB port where Clarett is connected is unable to sustain 3 A (a total output power of 15 W), then a LED will blink, making impossible the usage of the interface without the external power adapter.

View attachment 100534
MP3425 boost converter

Electrolytic capacitors used on the board are mostly CapXon KM series series, Jamicon SS and Jamicon SK series, but also few Nichicon PM series too. Temperature inside the Clarett is not high at all, the outer case is barely warm after hours of continuous operation, so caps temperature rating should not matter here.

View attachment 100535
Main board capacitors


The DAC chip inside is an AKM AK4413EQ 120dB S/N, 24-Bit 192kHz 4ch DAC, a rather obsolete part these days, not to be used for new designs, but still with a respectable THD+N of -104 dB.

The ADC chip is an AKM AK5388AEQ, 120dB S/N, 24-bit 192kHz 4ch ADC, obsolete part as well, but with a very good THD+N of -100 dB.

View attachment 100536
ADC and DAC chips


ADC inputs seem to be buffered by NJM8065 dual opamps, while DAC outputs seem to be buffered by JRC5532 opamps, probably one dual opamp for each ADC input and for each TRS output as well.

Analogue inputs gain is done by couple of THAT 1583 chip, a Low-Noise Differential Audio Preamplifier, able to deliver a 60 dB gain with only -128.9dBu (1.9 nV/√Hz) EIN of noise. Its THD+N is 0.0006% @ 0 dB gain, 0.001% @ 40 dB gain and 0.006% @ 60 dB gain, respectable figures for an analogue input of a home studio interface.

View attachment 100537
Two such THAT 1583 chips are controlling the gain for the two analogue inputs


A similar THAT preamp is also used inside the Motu M4, the THAT 6263. A quick compare of THAT preamps can be found below:

View attachment 100551
THAT digitally controlled preamps


The built-in headphones amplifier is powerful enough for a studio interface, definitely more powerful than Focusrite Solo Gen3 or Motu M4. It is based on the Japanese operation amplifier NJM4556AL, same as used as output buffer in Objective 2 headamp (just one single opamp, not couple of them, like in Objective 2). Theoretically, according to the datasheet, powered at +/-9.5 V it should be able to push up to 5.3 V RMS into high impedance headphones, approaching it’s 70 mA current limitations when pushed to low impedance cans. I was able to listen comfortable to my 40 Ohms Hifiman HE-560 planar headphones, which was not possible with Motu M4 due to the distortion when pushing up the volume, so there's enough juice on the 6.3 mm jack.



I was using 120 dB 16 Ohms sensitive IEMs and the background noise was there, but very low intensity, about the same as on Motu M4, totally not interfering with the music or audio tracks playing. The power before clipping on headphones would be about:
  • 180 mW / 30 Ohms (about 7 times higher than the M4)
  • 210 mW / 40 Ohms
  • 200 mW / 100 Ohms
  • 75 mW / 300 Ohms
  • 38 mW / 600 Ohms.

View attachment 100541
Clarett headamp - 4.7 V / 600 Ohms (pretty much as advertised by manufacturer: +16 dBu, which means 4.88 V RMS)


View attachment 100542
Clarett headamp - 2.45 V / 30 Ohms (top half clipping, but dropping voltage to 2.3-2.35 V makes the sine perfect again)

I can spot on the board one OPA2141 dual opamp followed by couple of JRC8065 opamps, but unfortunately I am not sure what they do, although I have a feeling that the two JRC8065 are summing up two balanced channels into two single-ended ones, then the OPA2141 might act as a gain stage for the JRC4556 headphones buffer, but I’m unable to prove that, as the PCB is quite opaque. However, this OPA2141 is the best performer from all opamps from the board, just not sure what is its purpose on the board.

The front panel/board has LEDs and potentiometers. I can spot three HC595AG 8−Bit Serial Shift Register with Latched 3−State Outputs. most likely to control the front lights, based on device state (INST, AIR, 48V etc.). I’ve also seen at least three more such shift registers on the main board.

View attachment 100546
Frontal board, with potentiometers and controls


The four potentiometers from this board are very similar with ALPHA RD902F-40-00D series, the one from headphone being probably logarithmic, while the other three probably being linear carbon tapers. Some Focusrite users seem to have troubles with such pots, same applies to ASUS Essence One users that are sharing similar APLHA pots, but time will tell how long will resist. One thing’s for sure, replacing them is quite difficult, because it involves a complicated way to dismantle the device, get out the boards and to then to unsolder double-sided soldered pins. Hope I’ll never have issues with these pots.


View attachment 100548
Frontal board, with potentiometers and controls

L.E.: Worth adding that the only analogue volume control is for the headphones output, while the other three potentiometers (for gain and master volume) are all digitally controlled.

What is the exact lifespan of these capacitors ?

2000 hours max ?

I see Endurance 2000
But Shelf Life only 1000 hours

What is the difference ?
 

telecode101

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gulp... capacitors in these interfaces have a lifespan? I am still using my old NI K6 ... it still works. are we saying in highend interfaces, there will be repair costs to replace capacitors in 5 to 7 years?
 
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are we saying in highend interfaces, there will be repair costs to replace capacitors in 5 to 7 years?
I'm using a receiver made in '83 and it works fine. :) It's all about how much these caps will dry out during time, but that doesn't means that we need to stress ourselves out due to the natural wear of the capacitors. Just listen to the music and, if the device will become defective, your local repair shop should deal with this with ease if the caps will need replaced.
 

telecode101

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I'm using a receiver made in '83 and it works fine. :) It's all about how much these caps will dry out during time, but that doesn't means that we need to stress ourselves out due to the natural wear of the capacitors. Just listen to the music and, if the device will become defective, your local repair shop should deal with this with ease if the caps will need replaced.
my guess is, if it breaks, its probably easier to get a new interface, unless you own a expensive $1000 interface.
 
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Yes, indeed, but the caps inside Clarett is quite easy to get them replaced.
 

AmadeusMozart

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What is the exact lifespan of these capacitors ?

2000 hours max ?

I see Endurance 2000
But Shelf Life only 1000 hours

What is the difference ?


Lifespan is determined by a number of factors. It depends on the temperature of the equipment (capacitor), the applied voltage and the amount of ripple current. I have capacitors rated for 8000 hours in a tube amplifier's PSU and when I worked it out they would survive at least 260 000 hours. 2000 hours is consumer grade and under normal use should last at least 8 to 10 years. By that time something better will be out and otherwise just replace all the capacitors. On the other hand I have some Hewlett Packard gear built in 1979 and the knobs were falling off, the case looks shocking but it still works. I now have to hunt down a bad ground due to oxidation from the aluminum case making for a bad contact. Only now do the power supply capacitors need replacement.

Shelf life: That is when it has been sitting on a shelf for a while and then you do not want to put full voltage on it straight away. The safe way to cope with that in design is to have capacitors rated for a higher voltage. Unless you know what voltage these capacitors are operating on then there is nothing that you can say. Often with old valve radios: if they have been in storage for years then do not switch them on as likely the PSU (Power Supply Unit) capacitor(s) will give you problems.
 

telecode101

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Posting for posterity in case anyone finds it useful. I did some tests between the new Clarett and a 10+ yr old NI Komplete 6 to see what the pre-amps can actually do. The test is on a nylon string guitar through an AKG condenser. Same player, same room, same mic.

Part 1 is Clarett, part 2 is Clarett w/ air function turned on. part 3 is the old NI Komplete.

https://soundcloud.com/telecode101%2Fmic-test-clarett-komplete
 
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telecode101

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"Can't find the page" :(

Sorry. I deleted it. I switched to a scarlette 6i6. No issues so far. It uses the same drivers as the Clarett. It seems more than powerful enough to drive my headphones and speakers/monitors.

The clarette is a very nice interface if you are using mics and recording live . I was defiantly able to hear a difference.
 
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Noticed that outputs 1/2 are more clean than outputs 3/4, see below:

Clarett2Pre_LineOut_CosmosMono_4.5Vscale_.png

Clarett outputs 3/4 @ about 4.5V RMS - SINAD of 108.178 dB
(measured with Cosmos ADC in mono)

Clarett2Pre_MonitorOut_CosmosMono_4.5Vscale_.png

Clarett outputs 1/2 @ about 4.5V RMS - SINAD of 106.196 dB
(measured with Cosmos ADC in mono)
So, an improvement of 2 dB in SINAD on the 3/4 outputs over the 1/2 outputs.
 

Tokyo_John

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Nice review, thanks for sharing it with us!

I picked up a Scarlett 4 last year since I was doing more communication from home and I upgraded my microphone to a SM7B which needs a lot of clean gain. Even with a cloudlifter in the chain, I still have to push the XLR mic input volume pot to about 9/10 to get in the steady green, and I have a relatively loud voice. Some reviewers have noted that Focusrite pots have a highly non-linear gain, with most of the gain coming at the cranked end of the knob turn…this is slightly annoying, however, the amplification I’m getting is super clean and good enough for professional recording (my room is the limiting factor, by far)…even without having a sense of headroom. I think one would need to spend 4-5X more to get a better interface.

On the other hand, I’m not happy with the DAC-Amp headphone outputs on Focusrite interfaces. I’d love to use it in order to save space, however, I’m also seeing distortion and artifacts…the same was true of my 2i2 Scarlett. So I’m running a separate dedicated DAC/Amp for headphone. I’m fairly sure that it adds latency to the path but for monitoring purposes this is not important.

I’m wondering if the Steinberg AXR4 might offer a better DAC/Amp for headphones, giving me a one-box solution and cleaning up my desk…but the Clarett is good enough to keep these thoughts at bay…for now.
 
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I’m not happy with the DAC-Amp headphone outputs on Focusrite interfaces.
Most of the studio interfaces are meant to be used with monitoring headphones, meaning closed-cans with above average sensitivity and rather low impedance.

However, besides the above headamp measurements you can also check out https://www.audiosciencereview.com/...2pre-usb-quick-measurements.10576/post-614109 and see that on 2V RMS @300 Ohms 2Pre's headamp has a SINAD of about 100 dB, which should be good enough for most of us.

AXR4 plays in a completely different league; however, it can output a "Maximum Output Level 75mW+75mW, 40 Ohm", per its datasheet, while 2Pre can output 210mW/40 Ohms per each channel. Did I said that I was listening with my HE-560 with above average SPL and listening experience was above my expectation for such a studio interface?

You may lookup the RME interfaces database, rack mount ones, and I'm sure you will be pleased with a higher SPL on the built-in headphones amplifier and a lower THD+N too. But on these SOHO studio interfaces I would say that 2Pre it's very hard to beat on the headamp part.
 
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