Njoe Tjoeb 4000: anti-resonance modification of the case
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Old Pa

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Ah!’s Njoe Tjoeb CD players have now gone through several iterations. Basically, the Dutch makers take a production Magnavox CD player and then modify it with improved transformers, socketed solid state digital stage, tubed analog, and a variety of user selectable improvements like feet and power cords. Virtually everything can be changed and played with to the owner’s heart’s content. Upscaleaudio.com has posted the report of Neville Roberts, a Brit who has played extensively with these modifications. His report is recommended reading and will not be duplicated here.

My Super Njoe Tjoeb 4000 is tricked out with the improved power cord, de-coupling feet, tube “ribs”, optional 24/192 upsampler, etc., but its Magnavox case, made of lighter metal than most Band-Aid boxes, seemed a sonic limitation begging to be addressed. Mr. Roberts approached the problem with a thin self-adhesive sheet of asphalt-based automotive sound deadening material stuck on the inside of the upper lid and reported good result. I, of course, had to make more of a mountain out of this particular molehill.

Parts Express (.com) catalogues an assortment of automotive sound dampening products aimed at those who participate in car stereo competitions. I don’t know much about these contests, but competition generally improves the breed, and it’s nice to have someone else pay for the R&D. My $20 bought me a 10”x13” lightweight vinyl sound dampening sheet (#268-030) and a 20oz can of Cascade VB-1S Pro Quiet Damping spray (#268-250).

Originally, I had planned to stick the 10”x13” vinyl sheet up on the inside of the Njoe Tjoeb’s thin metal upper case and then slather it with the sound deadening spray. After a little cranial percolation upon receiving and examining the damping products and their instructions, my plans changed. Instead, I pressed the vinyl sheet to the bottom of the unit between the feet (fits perfectly and can be pressed onto the plastic connectors that extend from the inside of the case) While the lower case upon which the “works” are mounted is of heavier gauge than the top case, it, too, needed some sound and resonance damping.

The inside of the upper case was first cleaned and degreased for best adhesion of the Cascade sound damping spray. This was accomplished using common spray household cleaner followed by window cleaner followed by denatured alcohol. Surface prep always pays off.

It took some time to mask the inside of the upper case to prevent overspray from interfering with refitting the upper case on the lower case. The Cascade VB-1S instructions indicated the product was to be applied warm (70-75F) and kept warm during curing and that no more than 1/32” thickness should be applied per spray coat. Warming the product in a bucket of warm water (as per label recommendations) also produced some impressive spray pressures. I got splatter up to 18” from the work surface. In retrospect, I should have masked at least the outside sides of the case as well. As it was Cascade recommends toluene as a solvent and I substituted Hoppe’s No. 9 to clean up the overspray.

Two coats of the Cascade Pro Quiet were applied with two hours drying time in between coats. Final coat was dried for an hour inside the house and in the sun and then an hour in a 120F degree oven to accelerate from the recommended drying time of 24 hours at 65F. This produced a layer about 1/16” thick, dry and not sticky, but amazingly anti-resonant.

The combined sound-deadening treatments completely transformed the Njoe Tjoeb’s case. Not only was it much more solid feeling and the transport more muted in operation, but additional sonic clarity was immediately apparent, especially in the lower octaves. The project took about two hours across the course of a day and produced exactly the results I had desired. Highly recommended!
 
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Old Pa

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After 4 to 5 hours of listening to various musical program on the modified Ah! Njoe Tjoeb 4000, I have got to say this mod was way better than I originally thought. The dampening material dropped the background noise level in addition to clearing up the lower frequencies of response. Now I know why Arcam put the work into the FMJ 23's case. Inner detail and small sounds all enhanced across a quieter background. Frequency response also seems smoother throughout.
 
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morphsci

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I use a 1/8" sheet of Sorbothane and a nice milled and stained piece of 3/4" oak on top of my Sony DVP-NS500V. Works wonders on those thin cases and spruces up the looks IMO. I originally tried it on my SCD-c333es but that thing is built like a tank and I didn't notice much improvement.
 
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Old Pa

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Exactly. I've also got an old Sony ES CD carousel that's built like a brick outhouse and it's always sounded good. I've compared published weights of components in the past as a loose measure of quality of materials and construction; maybe there's actually something to it.

The resilient automotive dampening materials discussed above handle a wider range of vibration frequencies, dispose of it internally, and can be added to existing equipment. The time of prep and application may keep manufacturers from utilizing them, but it makes them a most cost-effective tweak and fix for us.
 
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rickcr42

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good point about damping old pa,major improvements.

quick and dirty-zip lock bags filled with sand placed on top of the cover work great (lookslike crap though
)
 
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Old Pa

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The November 2003 Stereophile contains a complete (and favorable) review of the Ahh! Njoe Tjoeb 4000 and its accessories/modifications. I'm sure this has nothing to do with the fact that Kevin of Upscale also has several display ads in this issue. Perhaps this will be of interest to some here considering the Njoe Tjoeb 4000 as a source.
 
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Budgie

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I suspect the improvements were actually due to the Hoppe's#9!
 
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Old Pa

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Quote:

Originally posted by Budgie
I suspect the improvements were actually due to the Hoppe's#9!


*Gack!* He knows! I always put a little behind my ears after shaving in the morning, just to feel "pretty".
 
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Quote:

Originally posted by Old Pa
Mr. Roberts approached the problem with a thin self-adhesive sheet of asphalt-based automotive sound deadening material stuck on the inside of the upper lid and reported good result. I, of course, had to make more of a mountain out of this particular molehill.


On a similar player (the philips cd753, which shares 99.99% of the marantz cd5000, the case and two caps excepted), I put in a serious sheet of bitumen/silicone for cars. It makes wonders.

Btw, I heard a Tjoeb 4000 recently (on an awesome speakers system, not mine... sadly), it's a serious player. I still think however that the price is high for the results compared to solid states mods. Putting my player in front (i've only 250$ of mods on it), it was a really close game, no winners. The tjoeb was a bit more "fluid" but not as accurate.
 
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Old Pa

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The author of the cited Stereophile review makes the good and valid point that in high-end equipment, especially sources, rather often the difference in superiority is one of additional silence.
 
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