• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Cheap Audio Measurement Gear

Joined
Jul 26, 2020
Messages
17
Likes
19
#1
Hey guys, I am currently looking for a cheap audio anaylzer and oscilloscope to quantify results of amplifier and dac design. Aswell to mesuer the impact of Bluetooth Aptx HD codecs.

Unfortunately I am on a really tight budget so instead of buying the correct tools like a real audio anaylzer. I want to minimise my risk and buy things that have a dual purpose like an audio interface. Worst case is I fail at designing, then the interface can just default back to a normal audio interface for my audio tecnica condenser mic.

Enough introduction here is the short list of audio interfaces I have compiled.
MOTU M2
120 USD
DNR: 115db
THD: -97db
Noise: -128db EIN
Max Input:VRMS 2.449V


Focusrite Solo gen 3
111 USD
DNR: 111db
THD: 102.5db
Noise: -128db EIN
Max Input: VRMS 2.183V


Komplete Audio 1
109 USD
DNR: 109db
THD:
Noise: -128db EIN
Max Input: VRMS 2.4524V


Focusrite Clarett 2Pre USB
296 USD
DNR: 119
THD:
Noise: -129 EIN
Max Input: VRMS 8.7014

Reference:
https://quantasylum.com/products/qa401-audio-analyzer
449 USD
DNR:
THD: 108.5 db
Noise: -113 db
Max Input:VRMS19.95V

I'm leaning more towards the focusrite products. Again I don't want to spend much money so the solo seems to be winning right now. The 2pe is at a very good price locally so I'm getting tempted. Does anyone have any other recommendations? Is the 2pre really worth 3x the price of the solo?

I will need to aquire a audio attenuator and a decent oscilloscope.

More research needs to be done on audio attenuation. There doesn't seem to be much discussion on ASR. Does anyone have some useful information on this?

For oscilloscope I have a short list aswell

OWON XDS2102A 12 Bit Oscilloscope
Hanmatek DOS1102 Oscilloscope
OWON XDS3064AE 14 bit
Hantek 5072P

I currently own a really terrible hantek USB oscilloscope (6022be). It's absolutely awful, full of noise and terrible software. Ideally I would avoid USB scopes, I looked at the picoscopes as they can apparently get to 16 bits but I have little evidence of there noise floor so I'm not sure on them plus they are crazy expensive but if they can do everything in 1 package then they might be worth it. Also I'm ideally looking for a Higher vertical resolution and a low noise floor on my oscilloscope to do basic fft measuernts to check for oscillation, measuer power supply ripple and do basic fft analysis. I think I will need up to 100mhz but I might need 200mhz for dac design. Some of these dacs such as the new ess dacs need a external 100mhz crystal oscillator.
Any recommendations would be welcome aswell.
 

AnalogSteph

Addicted to Fun and Learning
Joined
Nov 6, 2018
Messages
596
Likes
415
Location
.de
#2
I would strike the Solo and the Komplete Audio 1 from the list, they're not really measurement grade. The M2 is about the minimum I'd consider. Clarett is quite nice as well. The QA401 actually uses the highest-grade converters of the bunch, has well-defined levels and as such is probably the best overall candidate for an audio analyzer. Note that you read the specs wrong, that's an input noise floor of -113 dBV when full-scale is at +6 dBV, so total input dynamic range = 119 dB.

None of the whole bunch actually deliver the kind of performance you'd need for evaulating near SOTA DACs right out of the box. You should be able to evaluate much lower THD using an external notch filter, and determining noise level probably wouldn't be an issue either (ironically, the traditional audio interfaces with their built-in preamps would stand a much better chance of doing so accurately than the QA401, if at the cost of messy level calibration), but one-shot SINAD is out of the question.

You should probably be looking at the diyAudio "Equipment and Tools" forum section, and scope wise head over to the EEVBlog forum or something.

Attenuators for speaker amplifier use are probably something you'd solder up yourself.
For single-ended outputs, make an unbalanced L-pad (e.g. 22k||22k + 681R, metal film) and add a series resistor at the ground leg (= 10k | 681R ~= 637R, maybe you can get some 649R or cobble something together from 619R + 18R) to get balanced impedances.
For bridged outputs, you'll need a double-L type balanced attenuator that should be connected to chassis ground in the middle. (If you make a floating attenuator it will attenuate differential mode but not common mode.) I don't envisage any issues from the tiny external ground loop formed with two channels, but you know, famous last words and all.
 

LTig

Major Contributor
Forum Donor
Joined
Feb 27, 2019
Messages
2,138
Likes
3,138
Location
Europe
#3
Hey guys, I am currently looking for a cheap audio anaylzer and oscilloscope to quantify results of amplifier and dac design. Aswell to mesuer the impact of Bluetooth Aptx HD codecs.

Unfortunately I am on a really tight budget so instead of buying the correct tools like a real audio anaylzer. I want to minimise my risk and buy things that have a dual purpose like an audio interface. Worst case is I fail at designing, then the interface can just default back to a normal audio interface for my audio tecnica condenser mic.
?
To measure SOTA DACs you need an AP. To measure good DACs you can use an RME ADI-2 PRO which RME designed explicitely for this task (besides its normal usage as recording interface). About 15 times cheaper than @amirm's AP but still expensive compared to your selection. Try to get a used one.
I will need to aquire a audio attenuator and a decent oscilloscope.
Forget about 12-16 bit scopes. Cheap ones are too slow, fast ones too expensive. For measuring slow high resolution signals you can use the audio interface, for fast signals use a cheap fast 2 channel scope. I'm quite happy with a 2x200 MHz Siglent SDS 1202X-E for ~340€.
 
OP
K
Joined
Jul 26, 2020
Messages
17
Likes
19
Thread Starter #4
After a lot of research i think i will end up going with the 2pre, I have no intentions of designing products that go above 16bit 48Khz since that is (arguably) to point of inaudibility.

Attenuators for speaker amplifier use are probably something you'd solder up yourself.
For single-ended outputs, make an unbalanced L-pad (e.g. 22k||22k + 681R, metal film) and add a series resistor at the ground leg (= 10k | 681R ~= 637R, maybe you can get some 649R or cobble something together from 619R + 18R) to get balanced impedances.
For bridged outputs, you'll need a double-L type balanced attenuator that should be connected to chassis ground in the middle. (If you make a floating attenuator it will attenuate differential mode but not common mode.) I don't envisage any issues from the tiny external ground loop formed with two channels, but you know, famous last words and all.
Do you have any resources where you got this kind of information?

I think i will start a new thread for information on Dummy loads and attenuators.

As for the scope i got no idea, might just get a cheap Unity or Hantek 200mhz scope.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,663
Likes
12,922
#5
After a lot of research i think i will end up going with the 2pre, I have no intentions of designing products that go above 16bit 48Khz since that is (arguably) to point of inaudibility.



Do you have any resources where you got this kind of information?

I think i will start a new thread for information on Dummy loads and attenuators.

As for the scope i got no idea, might just get a cheap Unity or Hantek 200mhz scope.
Just trust AnalogSteph on this. He is giving you very good information on the attenuators.

That is one advantage of the Quant Asylum device however. It has those attenuators built into it. They also offer a programmable load for amplifier testing. But it cost $289.

A cheap way to do dummy loads is using the heating elements of hot water heaters. You can get some pretty much at 8 ohms and they'll take lots of power. I seem to recall threads on DIYAudio forums about those.

https://www.diyaudio.com/forums/solid-state/275347-amp-output-testing.html


Also if you search dummy loads have been discussed on ASR. I seem to recall a supplier of very inexpensive high wattage resistors in that thread.

https://www.audiosciencereview.com/...ad-for-power-amplifier-torture-testing.10298/

https://www.audiosciencereview.com/forum/index.php?threads/asr-dummy-load-configuration.8026/
 

Rick Sykora

Addicted to Fun and Learning
Forum Donor
Joined
Jan 14, 2020
Messages
578
Likes
762
Location
Stow, Ohio USA
#6
After a lot of research i think i will end up going with the 2pre, I have no intentions of designing products that go above 16bit 48Khz since that is (arguably) to point of inaudibility.



Do you have any resources where you got this kind of information?

I think i will start a new thread for information on Dummy loads and attenuators.

As for the scope i got no idea, might just get a cheap Unity or Hantek 200mhz scope.
Am looking to upgrade my measurement abilities too. A very knowledgeable EE I know recommended the Rigol DS1054Z. See it here https://smile.amazon.com/dp/B012938...0-pcomp-feature-scomp-wm-5&ref=aa_scomp_sosp1

Have not touched a scope in about 30 years, so cannot help much, but thought it might help.
 
OP
K
Joined
Jul 26, 2020
Messages
17
Likes
19
Thread Starter #7

Balle Clorin

Active Member
Joined
Dec 26, 2017
Messages
112
Likes
130
#9
You do no need more than this DLock USB Dac and Sdif output

https://www.delock.com/produkte/S_63926/merkmale.html 30-40 usd

a 2usd optical cable mini type, and free REW software, and Umik microphone

I got the Focusrite Sol gen3 but do not use it anymore, it gives too inconsistent results,,,and does not measure better than the Dlock

I got a Siglent 1202X-E oscilloscope. I am happy with it ,does all I need and reasonable price. See reviews on You
tube
 
Last edited:
OP
K
Joined
Jul 26, 2020
Messages
17
Likes
19
Thread Starter #10
So the OWON XDS2102A is closer to the Rigol in price. Why do you like it better?
The owon scopes have real 12 bit and 14 bit ADC without comprising on the speed of the scope. Learn electronics YouTube channel did a teardown of the 12 bit and recommend it. Dave from eevblog toredown the 14 bit one aswell.

The owon noise floors are much lower then the rigols or siglents of the world. I was thinking these were more suited to audio design as I can get more detailed information on amplifier ringing. Also its a quick and dirty way to see if your amp is not distorting like crazy. I mean 14 bit is closer to 16 then 8.

Apart from the ADC there not much difference compared to the rigols. User interface is about on par mabey a little worse. But then again this is from what I've heard.

You do no need more than this DLock USB Dac and Sdif output

https://www.delock.com/produkte/S_63926/merkmale.html 30-40 usd

a 2usd optical cable mini type, and free REW software, and Umik microphone

I got the Focusrite Sol gen3 but do not use it anymore, it gives too inconsistent results,,,and does not measure better than the Dlock

I got a Siglent 1202X-E oscilloscope. I am happy with it ,does all I need and reasonable price. See reviews on You
tube
Do you have any measurements showing this dlock USB dac preforming well? You might be getting confused on what I'm trying to measure. I am not trying to measure the frequency response of speakers. I already have a setup to do this. I'm trying to measure the dac/amp performance. Something that @amirm does in his incredible reviews.

Your video was very interesting thank you for sharing!

I bought some non inductive resistors.

2 x 8 ohms 20w
4 x 4 ohms 20w
4 x 2 ohms 20w

These should cover dummy loads for power amplifiers.

I need to make a jig for making headphone amplifier measurement. I found a great guide online.
https://www.instructables.com/id/He... audio dummy load is,kind of "silent speaker".

This seems to be a great way to make a adjustable dummy load.
 
OP
K
Joined
Jul 26, 2020
Messages
17
Likes
19
Thread Starter #11
I was also wondering is a function generator any use for amplifier design? Most function generators have a terrible 0.5% of THD. I was thinking of just using my DAC (Khadas Tone Bored) as a function generator. Since it measures extremaly well. Only issue I can think of is the limited voltage output.
 

NTK

Senior Member
Forum Donor
Joined
Aug 11, 2019
Messages
478
Likes
943
Location
US East
#12
I was also wondering is a function generator any use for amplifier design? Most function generators have a terrible 0.5% of THD. I was thinking of just using my DAC (Khadas Tone Bored) as a function generator. Since it measures extremaly well. Only issue I can think of is the limited voltage output.
I think you'll want a function generator. Otherwise all your test signals will be band limited by the Khadas Tone Board to 192 kHz maximum. I'd think the purpose of your oscilloscope is to look at square waves and high frequency responses, etc. For that you'll need a function generator that can give you signals that have much lower rise times than the Tone Board.
 

Blumlein 88

Major Contributor
Forum Donor
Joined
Feb 23, 2016
Messages
9,663
Likes
12,922
#13
I think you'll want a function generator. Otherwise all your test signals will be band limited by the Khadas Tone Board to 192 kHz maximum. I'd think the purpose of your oscilloscope is to look at square waves and high frequency responses, etc. For that you'll need a function generator that can give you signals that have much lower rise times than the Tone Board.
I think the Khadas Tone board works up to 768 khz on PCM streams.

I don't know what the analog response and THD at elevated frequencies would be with it. Maybe someone has measured that somewhere.
 
OP
K
Joined
Jul 26, 2020
Messages
17
Likes
19
Thread Starter #14
Anyone have any recommendations for some good low distortion function generators? I think there might be some online DIY stuff that i can make myself but there is no grantee for accuracy.
 
Last edited:

watchnerd

Major Contributor
Joined
Dec 8, 2016
Messages
8,501
Likes
4,981
Location
Seattle Area, USA
#16
Anyone have any recommendations for some good low distortion function generators? I think there might be some online DIY stuff that i can make myself but there is no grantee for accuracy.
I'm also curious about reasonably priced, audio spectrum function generators.

I need one to use for reel-to-reel calibration.

And perhaps for some turntable purposes, as well.

And, yes, I've used software and a DAC, but I'd like something less unwieldy and faster.

I was thinking about something like this Koolertron:




Only $99.99 for the 15 MHz version.
 

AnalogSteph

Addicted to Fun and Learning
Joined
Nov 6, 2018
Messages
596
Likes
415
Location
.de
#18
I'm also curious about reasonably priced, audio spectrum function generators.

I need one to use for reel-to-reel calibration.

And perhaps for some turntable purposes, as well.

And, yes, I've used software and a DAC, but I'd like something less unwieldy and faster.

I was thinking about something like this Koolertron:
Frequency accuracy should be plenty for these purposes. I very much doubt that the sine is particularly low distortion by modern audio standards, but it doesn't sound like you really need that.
 

watchnerd

Major Contributor
Joined
Dec 8, 2016
Messages
8,501
Likes
4,981
Location
Seattle Area, USA
#19
Frequency accuracy should be plenty for these purposes. I very much doubt that the sine is particularly low distortion by modern audio standards, but it doesn't sound like you really need that.
Can you elaborate?

If it's not particularly accurate, or alternatively, it's overkill, I might as well use an even cheaper handheld function generator for $70.
 

LTig

Major Contributor
Forum Donor
Joined
Feb 27, 2019
Messages
2,138
Likes
3,138
Location
Europe
#20
Can you elaborate?

If it's not particularly accurate, or alternatively, it's overkill, I might as well use an even cheaper handheld function generator for $70.
Check the specs for distortion of sine signals and frequency precision.
 
Top Bottom