I Looked Into This Cheap DSP Noise Reducer for Ham and Shortwave — Here’s What I Found

One of the constant battles in ham radio and shortwave listening is noise.

Not just interference from power supplies or nearby electronics, but the endless layer of hiss, static, fading, and atmospheric noise that makes weak HF signals tiring to listen to for long periods.

That is why DSP noise reduction devices continue to attract attention from radio hobbyists. The idea sounds appealing: connect a small external audio processor to your radio and magically clean up noisy signals.

Recently I came across an inexpensive portable DSP audio noise reducer being marketed toward ham radio and shortwave listeners on Amazon. At first glance, it looked like one of the many generic DSP accessories that appear online every year.

But after digging through reviews, technical discussions, and experiences from actual HF operators, I discovered there is more to these little DSP boxes than I initially expected.

What This Device Actually Does

The first thing to understand is that this is an audio DSP processor, not an RF noise eliminator.

That distinction matters.

The unit connects after your radio’s audio output — usually through the headphone or speaker jack. Instead of filtering RF noise before it reaches the receiver, the DSP analyzes the demodulated audio and attempts to reduce unwanted background noise digitally.

In theory, this can:

• Reduce hiss
• Lower static levels
• Improve voice clarity
• Reduce listening fatigue
• Make weak SSB signals easier to copy

This type of processing has existed in amateur radio for years. Many modern HF transceivers already include built-in DSP systems, but external DSP units remain popular because they can be added to older radios and portable listening setups.

DSP Noise Reduction Has Always Been Controversial

One thing became obvious while researching this product: ham radio operators have very strong opinions about external DSP filters.

Some hobbyists swear by them.

Others believe audio-stage DSP is little more than an expensive tone control.

And honestly, both sides make valid points.

On RadioReference, several experienced operators discussed external DSP devices and noted that high-quality DSP systems can dramatically improve intelligibility when used correctly. One operator described the DSP in the Elecraft K3 as removing “90% of the noise” while remaining transparent to the audio. (RadioReference.com Forums)

At the same time, other operators argued that audio DSP can only do so much because the noise has already passed through the RF stages of the receiver. (RadioReference.com Forums)

That is an important point.

No external DSP box can fully compensate for:

• Poor antennas
• Severe local RFI
• Overloaded receivers
• Strong electrical interference
• Weak front-end performance

Good antennas and noise mitigation still matter far more than post-processing audio.

Where External DSP Actually Helps

Despite the skepticism, there is substantial evidence that external DSP filters can improve listening comfort significantly.

That distinction is important.

Most users are not claiming these devices magically turn unreadable signals into perfect copy. Instead, they reduce the mental fatigue associated with listening to noisy HF signals for extended periods.

Several reviewers of dedicated DSP audio filters described the biggest benefit as making weak voice signals easier to follow by reducing the constant background hiss and static. (eham.net)

That aligns with what many experienced HF listeners already know:
DSP often improves comfort more than absolute signal recovery.

The “Watery Audio” Problem

If you have used DSP noise reduction before, you have probably heard about the famous “watery” sound.

This artifact appears when DSP aggressively suppresses noise and accidentally affects portions of the voice signal itself.

Interestingly, reviewers comparing different DSP systems found major differences in how severe these artifacts become.

A review of the Xiegu GNR1 Digital Audio Noise Filter noted that it reduced noise on stronger shortwave signals with very few digital artifacts, making long listening sessions more pleasant. However, the reviewer also found that weaker signals sometimes disappeared entirely during aggressive filtering. (The SWLing Post)

Meanwhile, users of older DSP systems like the Timewave DSP-599zx often praised their ability to clean up weak voice signals while introducing only mild processing artifacts. (RadioReference.com Forums)

That suggests the effectiveness of external DSP depends heavily on:

• Signal strength
• Mode being monitored
• DSP algorithm quality
• How aggressively filtering is applied

Why These Devices Still Appeal to HF Operators

Even with limitations, there are several reasons why inexpensive DSP accessories continue to attract radio hobbyists.

Older Radios Lack Modern DSP

Many classic HF rigs and shortwave receivers were designed long before sophisticated DSP became common.

Adding an external DSP processor allows operators to modernize older radios without replacing them entirely.

Portable Operators Want Lightweight Gear

Compact DSP units fit nicely into:

• POTA kits
• Portable SWL setups
• Field listening stations
• Travel radio bags

Weak Voice Signals Benefit Most

Most reviews suggest DSP helps SSB voice more than anything else.

AM broadcast listening can improve somewhat, but weak SSB voice communication appears to be where audio DSP provides the biggest advantage. (eham.net)

Temper Expectations

One consistent theme appeared throughout nearly every review and discussion I found:
reasonable expectations matter.

Operators who expected miracles were often disappointed.

Operators who viewed DSP as a listening aid rather than a magic fix tended to be much happier.

Even highly rated DSP systems require experimentation with settings and careful adjustment to avoid damaging intelligibility. (eham.net)

That likely applies to this inexpensive Amazon DSP unit as well.

Is This Cheap DSP Noise Reducer Worth Trying?

For the price, I think it probably is — particularly for:

• Shortwave listeners
• Operators using older radios
• Portable HF enthusiasts
• Budget-conscious hobbyists
• Anyone curious about external DSP processing

I would not expect performance comparable to premium built-in DSP systems found in modern high-end transceivers.

But based on the broader history of external DSP products in the amateur radio world, these devices clearly can improve listening comfort under the right conditions.

And for many HF operators, reducing listening fatigue during long sessions is valuable all by itself.

Another DSP Audio Noise Reducer

Final Thoughts

One of the things I enjoy most about radio is experimenting with accessories that promise to improve the listening experience.

Sometimes those gadgets are complete gimmicks.

Sometimes they actually help.

External DSP audio processors fall somewhere in between. They are not miracle workers, but decades of operator experience suggest they can genuinely improve weak voice intelligibility and reduce listener fatigue when used properly.

This inexpensive DSP unit appears to follow that same tradition:

• portable
• affordable
• simple
• potentially useful with realistic expectations

If you enjoy experimenting with HF listening accessories, it may be an interesting addition to your radio bench or portable setup.

And if nothing else, it is another reminder that in amateur radio, even small improvements in readability can make the hobby a lot more enjoyable.

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