Project Goals:
- Excellent DMR audio from your DMR radio using computer style speakers with volume, bass and treble pots, or more…
- VU Meter to monitor levels of your HT’s and all other network users
- Ham level calibration of the VU Meter
- Appreciation for good, pleasant sounding user audio at the proper levels
DMR audio has been an issue since the very first networks went up in 2009. Now with thousands of DMR users using Chinese radios programmed by users who don’t know or care what they are doing, DMR audio has become problematic and use of Hotspots not helping either. MotoTRBO and other commercial radios tend to be very good out of the box and setup/managed by professionals using $35,000 communications monitors. But us hams struggle on a budget to get it right, at least those who care about decent audio. Most don’t try to address audio or even follow our basic settings for networking correctly on PNWDigital. But our technical people still try to provide the tools to help those who want it.
This page will provide information on how to use an Anytone HT (or 2 of um) in order to use a VU Meter locally. You will also as be able to listen to the very high quality DMR audio that you have now plucked out of the HT(s) to also drive a set of powered computers speakers.
VU Meter Stuff
This information one this page is primarily for the use of 1 or 2 Anytone HT’s. But you can use a 578 also, though the speaker jacks special need attention if you wish to use both (see below for more on particular strangeness).
I am using a pair of 868 spares for 2 different repeaters as they have sat happily in a gang charger for many years. Kenwood K-1 style adapter(s) get the audio out of the HT’s; one HT could be stereo left and the other stereo right, brought together with an adapter with 2 3.5 TS males to 1 3.5mm female stereo TRS inline jack so you can plug in your Bose hardware, or Radio Shack. It makes for a clean install and let’s you see the audios and experience DMR audio…which is surprisingly good when you get away from the internal speakers. It’s a 2fer project, visual and aural for not much more the the cost of the VU meter.
Block Diagram (someday maybe)
Hooking up the VU meter if very simple…K-1 adapter to get the audio out of the HT, a pot to load the audio output a tad as well as providing additional one time setting or “calibrating” the VU meter. You want to be able to set your HT audio to about 1/3 audio and then use the pot to adjust the audio into the VU meter. Some meters have their own gain controls (see below). Once set, you should never need to touch the audios. You might have figured out that this is a dedicated set-up…your HT will be receive only and sit in the charger for the next 10 years or 10 day, whichever arrives latest.
For the fine audio that will surprise you, then you will need a couple more parts for your listening pleasure. A simple RC network is needed to condition the audio side for the computer speakers. Simply, 2 22 or 33 ohm resisters or a 100 ohm pot and 1 – .05mf disc capacitor. The pot is across tip (speaker hot) and ground (shield) if used. Or the 2 resistors are series’ed together with that center point or the pot’s wiper then goes to the .05mp cap, then cap lead to the stereo speaker 3.5 plug, This RC network is needed to limit low response, eliminate the speaker pop and reduce the volume somewhat so the typical computer speaker’s volume control is about 1/3 to middle at default.
The Major Parts Lowdown
This K-1to 3.5 RS mono speaker out works with a TRS plug or a TS plug without keying the radio Tx
amazon.com/dp/B0DM7YG8T2 / 4 for $19 / Rx only inline 3.5mm out, which is all that is needed, doesn’t key the radio and is exactly what is
This alternative K-1 to 3.5 mono inline jack cable is optional but makes for a clean package with 2 HT’s in the gang charger: amazon.com/dp/B096XNHTH3 / $9 for 2 cables
Optional inline volume controls 3.5 stereo male female
https://www.amazon.com/dp/B099HXCQH3 / $7 each
Audio Equalizer: Your choice, I am using for this project, 9 band, +- 6dB (12dB range) with super specs not really needed for this project, bypass but no volume control, so use your computer speakers. https://www.amazon.com/dp/B0D72WRR3D / $50
I plan to use this equalizer but it has not arrived yet: amazon.com/dp/B0FX5XDL9S
7 band, 12dB range, stereo / $27
Really most any equalizer will do the job, actually none at all if you use the RC network to brute force condition the audio.
VU Meter options
DMR levels can drive each segment by level, so if you have a 50 segment VU meter, then you have up to 2% range per segment. So get the most LED segments possible if you wish to see levels at a granular level. The green/yellow/red types are the best as you can calibrate the yellows to be your desired or acceptable levels for a given audio.
I have a 50 segment meter that is 6 inches tall. It is the perfect size and makes it very easy to “See” slight or subtle audio levels and changes. I can’t find it online though. Next best on Amazon is a 32 segment dual or stereo display that is 4″ tall and has dual gain controls on-board. https://www.amazon.com/Audio-Level-Indicator-Amplifier-Atmosphere/dp/B0F4L2YDLN / $17
The VU meter should be inserted before the RC network to goes on to the speaker audio.
So the block diagram (as text) is: K-1 to volume control, to VU Meter and audio continuing on to the RC network, to the computer speaker input. You can use 2 K-1’s to support two Anytone HT’s for the dual VU meters, then can be summed back together after 2 RC networks for the stereo support by the computer speakers.
The 578 speaker jacks…are painful. The physical space between the 2 jacks are only about 8mm center to center. That makes most plugs with their covers too fat (large in diameter) for both to fit side by side. Likely Anytone did not intend both to be used at the same time. It appears that the upper jack is the active A band;s audio output and the lower jack is the active B band audio output. When not active, then the other band can be heard. So tying up a 578 is likely not a wise use of that resource, which is why I dug out a couple of vintage 868’s. So your mileage may vary and you won’t need the 2 K-1 adapters if you sacrifice your mobile radio.
This approach is not meant to be a finely calibrated $35k digital service monitor. But it will allow you to see your audio level live as well as everyone you hear. The superior Bose type audio is a nifty bonus. I’m in the habit when at the computer desk and on the air to watch my audio, looking to be sure I’m hitting in the yellow zone. Consider is DYI a 5 dollar Harbor Freight toilet lid, not like the one you would sit upon in the Space Shuttle. Once you see and hear it, you will a happy camper on a ham’s budget.
If someone wishes to draw this up, please do and I’ll add it to the page, saving me a bit of embarrassment.
NO7RF – Mike – Pullman WA
First Published: January 26, 2026 Last Updated: 2 weeks ago ago by Mike – NO7RF
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