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Noise Reduction System

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For all audible intents and purposes, the DBX system found in the NX40 eliminates tape hiss.

But it also increases the overall dynamic range capacity of a cassette deck, letting you record both louder and softer sounds than you are used to.

The combined result is that the NX40 will let you make cassettes with nothing added, ones as quiet as (and virtually indistinguishable from) the original.

The DBX noise reduction system can't do anything to improve noisy sources (records, broadcasts, other tapes) - it won't make them quieter - but it doesn't let anything be added.

With a really quiet source, the cassette copy will be crystal clear and just as wide in dynamic range.

If you haven't used DBX before, you'll be startled at how close to identical the copy sounds.

Now no dynamic range (even digital) is too wide for your cassette deck.

No other noise reduction system can do this.


Channels: 2

Input sensitivity: 100mV (1.6V max)

Output level: 1.6V (max)

Noise reduction system: dbx II

S/N improvement: 30dB (dbx II)

Dynamic range: 88dB

Frequency response: 50Hz to 15kHz

Total harmonic distortion: 0.5%

Dimensions: 9-1/8 x 1-7/8 x 6-7/8 inches

Weight: 3lbs


Related Catalogues

Silence and Super Dynamic Range

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Reviewed Oct 22nd, 2018 by

So far, I've just used this to make some cassette tape recordings from CD and vinyl. I will agree that this device successfully removes noise from tape (when recorded with DBX in the first place). I can't overstate that, the noise floor was brought down to zero. The dynamic range claim is harder to test- since none of my recordings really pushed the envelope. I would say my CD recording was more impressive than my vinyl recording. The DBX encoded tape was definitely near CD quality, and arguably equal to it. The recording I made from vinyl (again, onto a tape) was still very high quality, but sounded just a bit more dry, more synthesized than a record would. I have yet to play a DBX encoded record on this, but I have high hopes.

As far as ease of use goes, it's a mixed bag. Set-up was surprisingly confusing for only having 8 ports on the back. The manual assumes you are connecting this to a cassette-deck and receiver, and it doesn't mention substitutions (e.g., a reel to reel). The volume knobs are also oddly designed (could have been easier to use if they were in front). Lastly, the interface is very simple, just push a button for a DBX tape, DBX vinyl, or off. One thing about my particular device, it was rusty in terms of left/right channel contacts. Had a hard time pushing the inputs in to one of the ports, and the connections needed a few turns/pushes before they sounded clean.

Quirks aside, overall I'm quite pleased with the quality of this device. It was fairly inexpensive, and it let's you record nearly CD-quality cassette tape recordings. Once I try it on DBX encoded records I'll have even more to say.



re: NX-40

So I have now tried the NX40 on a DBX record as well, and I'm actually a bit less impressed. Mostly because the workflow to get it to work on records is needlessly complicated. You need to put the record through your tape monitor to get it to work. I tried in vain for an hour to get the box to decode the record directly, but it never worked, so I guess you need a receiver with a "monitor" function to use this.

Once I got it working, the records I tried had mixed results.

All the records were truly free of background noise and hiss- it was pretty remarkable. However, noise from scratches, clicks, and pops, was not completely removed- reduced, but not gone. The "full dynamic range" claim was impossible to prove on my equipment, but this is definitely where the records varied. One album sounded amazing- almost as good as live sound, and certainly as good as a Reel to reel or HQ digital recordings. The others just sounded like very clean records, but from a digital source (which, IMO, resulted in a flatter, more lifeless sound). The bass on DBX also appears to be enhanced artificially, which was a bit disappointing- felt less like "decoding" the music and more like turning up your graphic equalizer.

Overall, I'd still definitely recommend trying out DBX encoding for any audiophile or tech enthusiast, especially if you're into cassette tapes. The technology works, and arguably does what it promises, however, in an age where lossless digital audio is fairly easy to come by, DBX can feel underwhelming if you ignore the fact you are using analog media to play digital sound.

This website is not affiliated with or sponsored by DBX. To purchase NX-40 spares or accessories, please contact the company via their website or visit an authorised retailer.