Because of numerous close-by business/ industrial sites, my daytime HF operations from home are often inundated with an S5-S7+ noise floor, especially on weekdays.
They also impact on mobile ops when I’m working DX from some of the nearby hilltops with the Yaesu FT-450D in the car – despite the rig’s brilliant IF Shift & Width, Digital Noise Reduction and other noise eradication tools cushioning the blow.
After many attempts to resolve this with the RF-emitting culprits, the worst being a Dr Surgery and a Dick Smith Electronics store, I finally decided to try a good DSP system and picked up a Heil Clear Speech Speaker from ham radio suppliers HRO a few weeks ago.
The fine shape of the Aussie dollar meant I was able to land one here in Australia for just over $150 too.
This I consider to be quite a bargain given some local suppliers offer them at twice the price!
The Heil Clear Speech Speaker is said to “enhance the audio quality of car and truck fleet, emergency vehicles, marine and ham radio communications”.
According to the grapevine, it uses technology from the NCT Group and claims to have a number of improvements over the old Am-Com design which is no longer made.
On this note, I was looking forward to seeing whether or not this was the case after having spent a number of years using one of the Am-Com models and having fond memories of its noise annihilation performance on the citizens band.
Clear Speech Specifications
| FILTER CIRCUIT | |
| Noise cancellation characteristics: | 300 Hz to 3,400 Hz voice bandwidth |
| Electrical interference reduction: | 2 – 14 dB |
| Heterodyne reduction: | 40 – 50 dB |
| AUDIO | |
| Audio Input Jack: | 1/8 inch mini |
| Headphone output Jack: | 1/4 inch stereo (mutes internal speaker) |
| Audio Input Impedance: | 8 ohms. |
| Audio Output Impedance: | 8 ohms. |
| PHYSICAL | |
| Required Power: | 12 VDC 500 mA max. |
| Size: | 8 x 5 x 5 inches approx. |
First Impressions
When reviewing any speaker for radio comms use I always apply the same very simple criteria…
- Does it look good?
- Is it compatible with my existing station?
- Is it of solid make/construction?
- Does it improve my ability to perceive incoming signals or just redirect the sound?
- Is it good value for money?
- What is the reputation of the manufacturer?
- Does it do what it claims to do?
The Heil Clear Speech Speaker is housed in a sturdy plastic cabinet with a strong metal mesh grill.
Its black colour compliments most transceivers and DX-cessories. Mine included.
The design includes a four step DSP level switch, Sensitivity input level monitor (one LED to allow you to set the input level correctly without clipping the DSP stages), Variable Tone Control, By-pass Switch, External Speaker Jack, Headphone Jack and DC Power On/Off Switch.
All features are positioned down the right hand side of the speaker’s front.
The Heil Clear Speech back panel (pictured right) has 12 VDC input, mini speaker output, and mini audio input.
It came with a removable mounting bracket, fused 12 volt power cable and mono mini (3.5mm) to mini audio patch cord and was packaged in white polystyrene foam to ensure the product’s safety during transit.
My Findings
After some extensive testing in the mobile with the Yaesu FT-450D, I find the Heil Clear Speech Speaker to be fantastic at removing relatively steady noise and providing clean, undistorted audio.
Even with the volume cranked right up when I’m listening from outside of the car.
I can now copy most signals down to very low levels and the item works superbly in the shack with my Yaesu FT-950 also.
On my most recent portable DX session, for example, the QRM/QRN was a solid 6 on the signal meter.
When switched on, however, the Heil speaker tidied most of this up, making low signals from the Americas and OC regions accessible and enabling contacts I wouldn’t have been able to previously make.
The automatic heterodyne remover works very well also, making it possible to work 11m SSB at night with almost no difficulty at all.
One problem with this speaker noted on some of the world’s forums is its susceptibility to RF interference.
In order to avoid these issues, I suggest that you make certain you follow all grounding and other instructions to eliminate RF feedback through the speaker.
I’ve had no problems following Bob Heil’s instructions which came in the box.
Another way to reduce the RFI is to not power it from your common power supply that runs the transceiver.
Furthermore, If you run an amplifier and there is stray RF present in your shack then you’ll have to use a ground wire which plugs into the external speaker connection and attaches to your station ground system.
I’ve also read reviews on other forums criticizing the size of the knobs and the stiffness of the DSP selector switch.
In my opinion, however, these are attractive features rather than drawbacks.
Connecting headphones mutes the speaker but one slight negative I can report with the Heil Clear Speech Speaker is the low level hum I can hear through my Senheiser HD-280 headphones.
This same hum can’t be heard without the use of headphones but could lead to listening fatigue if the phones are used for too long.
This being said, I haven’t used a different set of phones since testing the speaker so perhaps the hum is only picked up by some super sensitive studio types like the HD’s.
According to the brief but useful instructions sheet, the volume control should be set to 5 o’clock – the highest position.
The tone control should be set between 10 and 5 o’clock depending on your listening preference.
The DSP control in the 0 position bypasses the DSP circuitry and it really shows the difference between the unaltered signal and the various levels of DSP.
My preferred DSP switch settings are 1, 2 or 3.
Summary
In conclusion, the Heil Clear Speech Speaker is a high-tech, low cost solution that has enhanced the receive capability of my FT-450D by providing crisp clear audio and chopped the white noise in half when working from the mobile – even with the FT-450D’s IF noise reduction turned on.
It effectively removes almost all QRN and heterodynes, making it very useful on the 11m band and others such as 40 and 80m when the band is open with Asia and Europe.
By all reports, Heil Sound no longer makes these DSP speakers after ceasing production after only 1000 units.
I’m not sure why as they’re a fine speaker in my opinion and compare favorably with other noise cancelling products on the market for ham radio use.
The value for money too is excellent!
Fortunately, many international dealers still have units in stock.
Alternatively, you can always keep a look out for them on eBay as they pop up as used items every now and then too.
I don’t have a manual with my speaker so I wondered just how one might add or remove the mounting bracket? I have the bracket but the mounting screws do NOT come out of the sides of the speaker making it useless.If you have a copy of the manual Please feel free too send me a copy in a PDF file.Thanks much & God bless.
W4KVW, Clayton Yarbrough