Topic: Anyone Use a Focusrite Scarlett for Measurements? (Read 1580 times)

Luckbad · « **on:** August 12, 2015, 06:44:25 AM »

I have a Focusrite Scarlett 2i4 and I'm starting to take measurements of amps and dacs.

I picked up a couple of Hosa Pro cables, one 3.5mm > Dual XLR, and one RCA > Dual TS.

I also have a Sound Blaster ZxR sound card with a discrete input card.

My issue is that theoretically the Scarlett should be really good for measurements, but I get far worse readings on the Scarlett than the Sound Blaster, and I don't know why.

For example, on my ODAC revB + O2, I get: Very good, Average x3, Good x3, Poor x1. On the Sound Blaster, I get Excellent x7 and Good x1.

Any advice for using the Scarlett to effectively take amp measurements? I tried Line/Inst/Pad combos and none seemed to make it much better. Should I give up on it and just use the ZxR?

Thanks!

maverickronin · « **Reply #1 on:** August 12, 2015, 02:11:33 PM »

I have a 2i2 but mostly use it for headphone measurements.

What do you get when you do a loopback into the 2i4?

firev1 · « **Reply #2 on:** August 12, 2015, 02:37:35 PM »

The scarlett series is hardly good enough for unloaded DAC measurements. For amp measurements you need to give the amp a load(like 16 ohms) to have it distort while driving the load.

Luckbad · « **Reply #3 on:** August 12, 2015, 04:20:08 PM »

Quote from: maverickronin on August 12, 2015, 02:11:33 PM

I have a 2i2 but mostly use it for headphone measurements.

What do you get when you do a loopback into the 2i4?

I'll try the loopback tonight.

Quote from: firev1 on August 12, 2015, 02:37:35 PM

The scarlett series is hardly good enough for unloaded DAC measurements. For amp measurements you need to give the amp a load(like 16 ohms) to have it distort while driving the load.

How do you give am amp load like that while connected to the Scarlett? Do I need an resistor adapter? I actually have one of those in my mailbox right now that gives 75 Ohms of load (in theory) that I'm going to try out with sensitive IEMs on a powerful amp.

Thanks for the replies, both of you. I'm still new to measuring amps/dacs and I'm about to figure out how to do full-size headphones as well. I already use the Scarlett with an electret mic to measure IEMs as best I can.

Hands · « **Reply #4 on:** August 12, 2015, 04:47:30 PM »

I could actually use a variety of resistor adapters myself for DAC and amp measurements. I'm too dumb to know how to make them myself unless I have a guide full of pretty pictures.

firev1 · « **Reply #5 on:** August 13, 2015, 04:52:32 PM »

A nice guide for a dummy load http://tangentsoft.net/audio/hp-dummy.html. Personally I would use BA drivers for low ohm loads. essentially you have a split cable to the interface and to the load.

Hands · « **Reply #6 on:** August 13, 2015, 06:17:00 PM »

I would need a guide more like what Pete Millet did for the DIY Butte amp (here are your parts, here are your pretty step-by-step pictures, so plop these parts here and solder away, don't worry about anything else, because I've done it all for you). Yes, I'm that dumb in this area. Using test equipment and software, I can eventually figure that out and concepts behind it...mostly. Sometimes. Maybe. But anything that falls in the circuitry or electrical engineer area, I'm essentially a moron. Trying to learn what I can, slowly, but that area is not my brain's forte. So, if you know anything like that for both an RCA load for DACs and something with a 1/4" connector for amps, that would be absolutely wonderful for me. That link does a good job with the parts, but everything else is not laid out for total idiots like myself. Does that even have an output to send to a measurement device?

Luckbad · « **Reply #7 on:** August 13, 2015, 06:35:05 PM »

Quote from: hans030390 on August 13, 2015, 06:17:00 PM

I would need a guide more like what Pete Millet did for the DIY Butte amp (here are your parts, here are your pretty step-by-step pictures, so plop these parts here and solder away, don't worry about anything else, because I've done it all for you). Yes, I'm that dumb in this area. Using test equipment and software, I can eventually figure that out and concepts behind it...mostly. Sometimes. Maybe. But anything that falls in the circuitry or electrical engineer area, I'm essentially a moron. Trying to learn what I can, slowly, but that area is not my brain's forte. So, if you know anything like that for both an RCA load for DACs and something with a 1/4" connector for amps, that would be absolutely wonderful for me. That link does a good job with the parts, but everything else is not laid out for total idiots like myself. Does that even have an output to send to a measurement device?

It looks to me like it doesn't have an output, but expects you to use a Y splitter and hook one of the ends up to this. Which means you could just use a Y splitter and hook one of the sides up to a headphone if you don't care about it surviving tests since the volume will be really loud. I'm wondering if my resistor adapter will do the job, though. 75 Ohms of extra load? Dunno. I'll try it out this weekend.

ultrabike · « **Reply #8 on:** August 13, 2015, 07:45:07 PM »

I use a 2i2 for headphone, amp and DAC measurements. The line in should be high impedance. Like most and any line input. You need indeed a Y spliter and loads. I made my own loads using two resistors per load going from + to GND and - to GND. The loads are soldered to ab RCA male connector. I made a pair w 4 33 ohm resistors, 300 ohm resistors, and 150 ohm resistors. I can't remember what type I used but I think I used Metal film. I'll make more to cover the ones w decide are stadard here.

I will qualify the 2i2 interface w the O2 n maybe the ODAC Rev B. I've already done measurements w the Sansa Zip n think I got very similar results than NwAvGuy. Except I don't think he pointed out some issues around the expected distortion values.

Loopback shows the 2i2 is decent as a single ended DAC n very good as a balanced interface.

When I get back from vacations I'll try to take some pics.

Hands · « **Reply #9 on:** August 13, 2015, 09:17:30 PM »

Ultra, any chance you'd be able to make me some loads w/ RCA? Removes the idiot, me, from the equation. I'd pay for parts, labor, and shipping, of course. PM me if you want.

Author Topic: Anyone Use a Focusrite Scarlett for Measurements? (Read 1580 times)

Luckbad

Anyone Use a Focusrite Scarlett for Measurements?

maverickronin

Re: Anyone Use a Focusrite Scarlett for Measurements?

firev1

Re: Anyone Use a Focusrite Scarlett for Measurements?

Luckbad

Re: Anyone Use a Focusrite Scarlett for Measurements?

Hands

Re: Anyone Use a Focusrite Scarlett for Measurements?

firev1

Re: Anyone Use a Focusrite Scarlett for Measurements?

Hands

Re: Anyone Use a Focusrite Scarlett for Measurements?

Luckbad

Re: Anyone Use a Focusrite Scarlett for Measurements?

ultrabike

Re: Anyone Use a Focusrite Scarlett for Measurements?

Hands

Re: Anyone Use a Focusrite Scarlett for Measurements?

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Author Topic: Anyone Use a Focusrite Scarlett for Measurements? (Read 1580 times)