Harley Benton CPT-20

CPT-20 works well. Screen turns green and stays green when string is in tune. If it won't stay green, it's the string, not CPT-20.

I have about five Thomann CTG-10 Clip tuners, so the screen was quite familiar. I consider CPT-20 like a CTG-10 in the pedal form. Nothing bad about it. I can still see the screen w/o my glasses while standing. Just about.

I also have a few Thomann CTC-50 Red tuners in my concert guitars cases. I find CTC-50 superior to CTG-10. I also have a Behringer rack tuner, which works well. The rack tuner is plugged into the recording out of my M/B Quad preamp, so I can't mute while tuning. That can be annoying playing live. I only use it during concerts if there is no other way. With clip tuners I can tune in silence, but I like to have another option for tuning in silence on the pedal board.

So I was looking for a cheap tuner/mute button with a small footprint to save precious space on PB. And CPT-20 would actually be a great choice if only a bit more attention was paid to details. The power input is like really loose, it moves into all directions. Not just a bit, more like 2 mm wiggle room. Also the switch feels cheap. It's also just a bit low, I used a S-Connector between a small buffer pedal and the CPT-20 and it's not a perfect match. The absence of battery does not bother me at all. The thing I really like was the brushed aluminum face of the pedal. More pedals should be like that.

All in all, could be made better. But it works. We'll see how long.

It's a very simple unit, one butten for on/off and a screen and some LEDs for tuning. The tuning (what it's designed for) is okay. More expensive units are probably more precise, but for home use it suffices.

Pro's:
The unit is cheap, small and easy to use. The screen is nice and big and tuning it this way is good to do. Besides it looks quite fresh.

Cons:
The red LEDs are so bright you can't look at the unit without eye dameage. I had to tape them off to actually use the unit. Who designed this??
But the biggest issue: The unit distorts the sound in bypass mode! When playing a bit hard on my single coil guitar it distorts. I can imagine this being a far worse problem on humbucker or active guitars. Therefore I'll be putting it behind a true bypass splitter I still have lying around and would not recommend this unit for whoever wants to use it on a serious pedalboard.

The CTP-20 is a really compact tuner, it sits nicely on compact pedalboards for maximum space efficiency, also the tuning is alright although you can see that there's some delay between playing and displaying the note. On the really bad side tho there's two main factors: the three LEDs are too damn bright and make it impossible to see the dimmed blue display with the note and the "needle" to precisely tune your instrument, and most importantly the pedal is not actually true bypass! It distorts the sound (A LOT) when in bypass, therefore making this pedal useless since a tuner is usually the FIRST pedal in an FX chain!
Do not get this unless you wanna throw 18€ in the thrash or if you wanna spend 8 hours trying to find where the issue is in your pedalboard, only to find that it was this fake true bypass pedal.

Good:-
This is a cheap and cheerful A440Hz [not adjustable] tuner with proper bypass.
Nice and quick to react, and makes it clear when a string's in tune.
Copes with Drop A on guitar, and B on a 5 string bass if it's first in chain, and happier with bridge pickup signals.
You know when it's on as the indicators can be seen from the ISS. It's also got a positive footswitch.
Tiny footprint on a board.

Meh:-
Clearly made in the same factory as EastRock, Donner and others, as it's identical, down to the magnetic flappy box. It also has exactly the same flaw, a loose jack socket. The hole in the case has been cut slightly oversized, so the socket is loose, but the jack itself is a good fit. Mine's in a pedalboard, so accidental disconnection isn't a worry.
Only powered by the socket [due to it's nano size].
No way to adjust frequency from A440HZ.

TLDR:-
Cheap, cheerful, fast but built to a price. Worth that price.