AUDIO
OUT
AUDIO OUT
L
R
By Jake Rothman
Handyscope HS5 USB oscilloscope review
I
wouldn’t normally review a
digital oscilloscope; after all, I’m
very much an analogue specialist.
However, the more I thought about
it, the more I realised that if I can
successfully run a USB oscilloscope,
then probably anyone can! With that in
mind, here are my impressions of the
Handyscope HS5 USB oscilloscope, as
shown in Fig.1.
The Handyscope HS5 is made by
TiePie engineering, a Dutch company
developing and selling computercontrolled measuring instruments. It
is sold in the UK by iTP (innovative
Technology Projects Ltd), based just
outside Cambridge. Just to be clear, I’m
reviewing a standard for-sale model. It’s
not a freebie and I had to return it after
I completed the article.
Analogue angst?
In the past, I’ve dismissed most
affordable (£500-£1300) digital scopes
with disdain. They often have just 8-bit
vertical resolution and awful 640-line
low-res LCD screens. My field – analogue
audio – is all about smoothness in
amplitude. It’s impossible to see tiny
power amp crossover and converter
non-linearities when the glitches you are
looking for are smaller than the visual
steps on the scope. For this reason,
many analogue audio engineers are still
wedded to their old Tektronix and other
cathode-ray tube oscilloscopes (CROs).
Their vertical resolution is only limited
by the noise in the Y amplifiers and
beam width.
Another factor is modern digital
scopes can have huge bandwidths,
sometimes up to several GHz. This is
quite unnecessary for analogue audio
– 20MHz is more than enough. In other
words, while this GHz-capability has
to be paid for, it is never used in audio.
Last, but not least, in my experience,
the biggest digital scope issue for
audio enthusiasts is obtaining 16-bit
vertical resolution, which I think is
the minimum usable for audio work. I
44
Fig.1. An understated box that does a hundred things... once you’ve learned to use the
software. The rear panel has a captive USB lead and a power socket for the supplied
power supply. The PSU is worth using because then no current is drawn from the
computer. The Handyscope draws 130mA without the software running and 610mA
in normal scope mode. This rises to 860mA with the signal generator switched on
with no load. The AUX sockets are for combining multiple Handyscopes. The 9-pin D
connector has internal and external clock pins, generator stop and start, power in and
out, I²C serial communication bus and some low-voltage TTL connections.
remember using an impressive Keysight
Agilent MSOS804A digital scope at the
university where I taught. It was the first
one I’d found satisfactory for audio work,
but imagine my disappointment when I
found back then it cost £60k.
Despite my general scepticism, I’ve
always known that there are some
things only digital scopes can do,
things that are very useful for audio.
For example, transient capture and
data logging, which are great for fault
and thump analysis. Plus, nowadays,
I can see that screen resolution issues
can be cheaply overcome by using
a modern high-resolution computer
monitor. In other words, a USB scope,
in conjunction with a computer could
potentially create a very satisfactory
system for audio work.
Practical Electronics | March | 2023
with the main computer USB lead – the
latter is permanently connected to the
unit. A nice touch is two high-quality
printed manuals, one for general use
and the other hundred-pager for the
scope’s unique Multi Channel software.
A typical setup for the scope is shown in
Fig.3. One thing I miss is some physical
medium, such as a CD, for the essential
software. Living in a rural area that has
occasional network blackouts, it’s an
omission that makes me feel insecure.
Still, it’s not that difficult to make one’s
own offline backups.
Installation
Fig.2. No, I didn’t open it! Erik at TiePie sent me this internal shot – solid engineering.
Note the metal screening cans on the input stages and signal generator sections.
While hunting for a possible digital
scope I noticed that TiePie’s HS5 is a 16bit resolution instrument and that it also
comes with spectrum analyser capability
and an internal signal generator, where
almost any test waveform could be set
up. I’ve been in the market for a spectrum
analyser, having been disappointed with
the one on my Audio Precision analyser
and other specialised bench units, so
these features clinched it for me and I
asked for a loan unit to test and review.
I’m pleased to say that after-‘sales’
support was good – TiePie replied to
all emails and phone calls in a fast and
friendly manner. In particular, Erik
Tigchelaar at TiePie happily dealt with
some tricky technical questions. He even
sent me a photo of the scope’s internals,
revealing a neat, highly professional
construction (see Fig.2).
Unboxing
The unit includes two probes with all
the standard accessories such as spring
clips. There’s a USB power lead along
I must confess that there was one
other thing that had previously
put me off taking the digital scope
plunge – like all computer-based
instruments, I was worried about
tackling the inevitable fun and games
around software installation and the
learning curve of using instrumentation
software. (Analogue scopes had become
completely standardised by about 1970
and once learnt, they’re ‘like riding a
bike’ – not so digital scopes).
The unit is not ‘plug-and-play’.
I had to download the driver and
measurement software (called Multi
Channel) separately from the website. To
do this, I had to look very carefully to get
the correct ones. There is quite a choice,
including legacy systems: Linux, MSDOS, Windows and lots of different scope
models. The unit was fine on Windows
7 and Windows 10 64-bit, but I had no
luck with the 32-bit versions on my
friend’s old laptops. With the Windows 7
installation, I got a bit confused because
the Multi Channel software had ‘driver’
in its name, making me forget to install
the actual USB scope driver!
Operation
Fig.3. A typical messy test bench set-up showing the scope connected to a mixing
desk channel.
Practical Electronics | March | 2023
Once installed, I found the Multi
Channel software straightforward and
usable – even for an ‘analogue’ person.
On a Windows 7 Hush PC desktop
with 16GB RAM and an SSD, the scope
was very fast with the lowest latency
(delay between input change and
display change time) I’ve experienced.
This makes it great for trimming and
peaking analogue circuits. Of course,
there are so many variables that affects
acquisition time that it’s possible I
did not have every setting the same
when doing comparisons. Latency is
one of the things I hate about digital
instrumentation. A long delay between
doing something and then the display
changing has always made me feel
it’s a simulation and breaks the handdisplay-brain feedback loop essential
for experimental work. Here, the
Handyscope behaved admirably.
45
mistakes, so I occasionally had to click
out/in the TiePie icon and start again. If
you are a software savant these things are
no problem. If not, it can be confusing –
but as with all software, ‘practice makes
perfect’, and I freely admit I’m a beginner
with Multi Channel.
Storage scope
Digital scopes can capture transient
events by virtue of their storage
capability. It can be very difficult to see
something like a humble switch bounce
on an analogue standard scope. Fig.4
shows a horrific switch guaranteed to
send any control system into apoplexy.
(You’d select floor 2 on the lift and end
up at 29!). Clearly the HS5 caught the
multiple bounces with ease.
Metering
Fig.4. The storage facility enables transient events to be seen, such as this switch bounce.
Earthing
There is always the possibility with
computer-connected equipment that
noise from the computer’s power supply
contaminates some of the measurements.
This could be a problem with some old
mains-powered desktops, but a batterypowered laptop avoids this problem. I
had no problems, but out of interest, I
did try a hifimediy.com USB isolator
between the Handyscope and the
computer. This created more problems
than it solved, causing the software to
crash when it ran out of speed with
sample rates of 500kSa or over. In this
case, it was clearly a case of follow the
instructions and keep things simple.
Results
I’ve only included a few static screen
shots, since the real beauty of audio
scope measurements is in the dynamics.
There’s a button in the file menu in the
upper Windows tool bar that says ‘save
image’ which is how these screen shots
were obtained. I accidentally hid/closed
the tool bar at one point. Only a hard
power-down of scope and restarting
the computer restored it. The system
otherwise saves your settings and your
The scope has a very useful multimeter
facility. I found the massive virtual
analogue scale very good for teaching
with a big HDTV screen. There is a
measurement icon on the scope that
will give you everything you need, such
as frequency, Vrms and Vpk-pk. The days
when students had to read graticules are
gone. Deskilling perhaps, but definitely
delivering greater accuracy.
Frequency response
I managed to capture some excellent
audio results, such as a frequency
response plot with the correct log axes
or dB level vs log frequency. The plot
shown in Fig.5 is for a speech processor
filter which I use for ‘NASA moonlanding vocals’ in music. Note how the
response curve is ‘blocky’ on the low
end, this is because I did it quickly. If
I had swept the response more slowly
there would have been more cycles
in the low frequencies for the system
to acquire, improving the accuracy.
There are always such speed/accuracy
trade-offs in measurement. Obtaining
such response curves generally needs
expensive equipment, such as an Audio
Precision analyser, so I was pleasantly
surprised that the HS5 did such a
good job. Normally, audio response
curves only go down to 20Hz, but I was
pleased to see I could set this minimum
to a much lower value (down to 1Hz)
enabling me to check for coupling
capacitor anomalies.
Spectrum analysis
Fig.5. Frequency response plot of a speech band-pass filter. This was done by
selecting a sample rate of 50kHz and a recording length of 16.38k samples.
46
The Handyscope performed spectrum
analysis particularly well, much
better than other bits of software I’ve
used. My bench-top signal generator
has developed a slightly lop-sided
waveform. The fast-Fourier-transformderived (FFT) spectrum analysis plot in
Fig.6 shows there are unwanted even
Practical Electronics | March | 2023
harmonics in the triangle waveform.
It’s possible to allow the FFT algorithm
to optimise its resolution by setting
the sampling rate and the record
length separately to find particular
frequencies in a noisy signal. By
raising the Multi Channel integration
time, the low-frequency resolution
increases – an excellent way of looking
at harmonics buried in noise.
Distortion
While playing with the Multi Channel
software I discovered the unit could
perform a percentage total harmonic
distortion (THD) measurement by
adding up all the harmonics in the
spectrum analysis plot and comparing
these to the fundamental. This takes
quite a bit of maths to do by hand. In the
true software-designer-fashion hated
by hardware knob-twiddlers like me,
it was difficult to find this function.
It’s a right-click drop-down menu, only
available if you move a vertical marker
cursor onto the fundamental spike on
the spectrum analysis plot. Then you
have to click on the abstract icon called
‘value window’ and finally, there’s
a little THD symbol you can click.
Again, standalone THD measuring
devices are expensive, so this function
also justifies the Handyscope’s cost.
If you can’t remember how to access
this function then fortunately fallible
human memory has been anticipated
by allowing settings to be stored (along
with images). Fig.7 shows the THD of a
very simple oscillator based on an RA53
thermistor designed by John Linsley
Hood. I always thought it sounded pure.
Now I know it is, with just 0.016% THD.
Fig.6. Spectral response of a bad signal generator. This was a distorted 1kHz triangle
waveform, which is supposed to have only odd harmonics. (Excuse the numbering on the
frequency axis. It is possible to slide the cursor along to get whole numbers as in Fig.7.)
reassuring relay click from the box when
the output is switched on. (The AWG
defaults to off, useful for preventing
hearing damage!) I did some basic tests
and found it could deliver a maximum
output of 24Vpk-pk sinewave at 1kHz,
the standard audio test frequency. The
output impedance is 50Ω. When loaded
with a 51Ω resistor the output dropped to
12Vpk-pk, as expected, and there was no
clipping. This equates to about 720mW,
which may tax some low-power USB
sources, which explains why TiePie
recommend using the external power
supply when the AWG is switched on. I
measured the distortion using the builtin spectrum analyser and found it to be
0.023%, which is pretty good.
Petrol heads
I noticed a whole suite of software
measuring tools for automotive
applications, so if you want to set your
cam belts and fuel injectors, you will
love it. It seems this is one of TiePie’s
main markets.
It’s even possible to average out multiple
FFT readings to further reduce noise,
as astronomers do to analyse distant
celestial bodies, a unique facility. Getting
to this function is via the object tree and
involves a lot of clicking. I averaged 8
FFTs together for the RA53 oscillator,
which enabled the harmonics to be seen
more clearly, as shown in Fig.8. It took
about 10 minutes to compute.
Waveform generator
One aspect of the Handyscope I
particularly liked was the built-in
waveform generator. It has its own output
BNC connector and can be set using
a little window to output almost any
waveform – hence its name, ‘Arbitrary
Waveform Generator’ (AWG). It can
output pulses, tone bursts, asymmetrical
sinewaves… up to 40MHz for the 540
model and 5MHz for the 055. It is
accessed by a funny-looking icon that I
guess is supposed to represent the front
panel of a bench generator. There is a
Practical Electronics | March | 2023
Fig.7. Spectral response of a clean RA53 1kHz sinewave oscillator. Notice how the
THD+noise figure is given as well (box, top-left corner).
47
Further information
iTP (innovative Technology
Projects Ltd)
https://www.itp101.com
+44 (0)1480 700158
info<at>itp101.com
Summary
Let’s get the question of cost out the way
first. The HS5 isn’t cheap, priced at £895
for the basic model HS5-055, rising to
£1331 for the HS5-540 XM (which has
ten-times more acquisition memory and
a 40MHz sampling rate). So, it’s not a
beginner’s unit. It’s aimed at experienced
hobbyists (and of course professional
users). The above prices are excluding VAT
and shipping, which can vary. Luckily, the
cheaper HS5 5MHz sampling model offers
more than enough facilities for audio work.
(There’s a very similar 16-bit Pico scope,
the 4262, which costs £1025). One crucial
point when you weigh up the unit’s price
and value-for-money – do consider what
this understated ‘little black box’ can do.
It’s actually relatively inexpensive because
it replaces a whole slew of separate pieces
of test gear. Remember – it’s not just a
scope, but also a meter, signal analyser,
plotter, function generator and more.
Fig.8. Averaged FFT spectral response of RA53 oscillator set to 330Hz . Note how the
noise floor has been reduced relative to the harmonic spikes.
The HS5 works beautifully on the
bench and is the ideal ‘rucksack scope’
in conjunction with a compatible laptop
– so much easier to carry on the train.
No more struggling in a car stacked with
20kg of CRO, bench signal generator and
plotter. For me, it was the specialised
measurement functions that made it
really worthwhile. I want to buy it,
but right now it’s a case of ‘heating or
scoping’, so I may have to wait and hope
for a warm spring!
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