May 2001

The AH! NJOE TJOEB 4000 CD Player

Review by Dick Olsher
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  OK, let's first sort out the Dutch pronunciation: it's the AHA! New Tube 4000 - the latest Marantz CD player modification from Herman van den Dungen and the DÉ HIFIWINKEL in Holland. If you're unfamiliar with the earlier mod, the Tjoeb '99, I strongly suggest that you search our Archives for my glowing review of that unit, which formed the front-end of our recommended Y2K system.

Since the Marantz CD-38, the chassis for both the Tjoeb '98 and '99 mods, was discontinued last November, the Hi Fi Corner crew was forced to switch production to the CD-38's successor, the new basic model CD-4000. This was done with some reluctance due to the increased cost of the CD-4000, but let me say that I would gladly pay the price differential just for the improved cosmetics and mechanical integrity of the new Marantz player. The good news is that the Njoe Tjoeb is still affordable (US$579) and its price/performance ratio is as stupendous as ever.

The Njoe Tjoeb mod is the result of some nine months of experimentation to refine the basic sound of the Marantz unit, using the same basic tube output stage as before. That, of course, was essential in order to preserve the musicality of the previous mods. The output stage still uses the Philips Jan 6922 Military Grade NOS tubes, but at a slightly increased plate voltage for better performance. The tube filaments are now in parallel instead of series connection. Check out the new "heavy-duty" tube sockets - a nice feature for incurable tube rollers (see tube board below).

In addition, the power supply filter capacitor bank has been increased to over 30,000 microF, which proved to be just the right amount for this player based on listening tests. The listening panel also preferred a higher filament supply filter capacitance, the "right" value being 6,600 microF. Passive part choices were also made on the basis of listening evaluations, resulting in an optimized parts list that will be used during the life span of the Njoe Tjoeb 4000.

As with the Tjoeb '99, the stock transistorized muting circuit has been disabled. A CD player needs to be muted occasionally, as there are places where very loud pops can occur. The Tjoeb uses a relay which is either in or out of the signal path. This costs more, but sounds better. The only downside with the Njoe Tjoeb is a soft click when the player is started, paused, or stopped. Gone are the clicks between tracks experienced with the Tjoeb '99.

Apparently, some folks struggled a bit in negotiating the Torx screws that hold down the top of the chassis. It really help to have the right tool for the job, and every Njoe Tjoeb now comes outfitted with a Torx #10 screwdriver. This is a nice touch, and believe me, you'll definitely want to open up the chassis and experiment with tube substitutions.

The output voltage is set at the factory at 2.5 V. However, the output voltage is adjustable via a series of fixed resistors. All that is required is that you solder and desolder small "bridges" on the board to obtain four basic voltage values: 5, 2.5, 1.25, or 0.7 V. This is a better sounding and more reliable solution than using a potentiometer for this purpose. Most preamps should not be susceptible to overload at a nominal input voltage of 2.5 V. However, depending on the gain of your preamp, backing off the CD player's input voltage may be necessary to allow you to crank open the preamp's volume control.

There is also added value, as the Njoe Tjoeb features as standard the AH! AC NoiseKiller, AH! SuperCrystal oscillator, and a coax digital output. These items were previously only available as options for the Tjoeb '99, but since most customers opted for the upgrades, AH! Decided to bundle them with the Njoe Tjoeb. Thank you, AH! Currently, the only options are a transformer coax digital output, fancier feet (dubbed TjoebSjoes), and a better grade AC cord. My unit was delivered without these two extra touches.

The Sound

Let me ask this question once again: just how good is the Tjoeb? The old Tjoeb '99 waltzed its way into the Y2K system and established itself as my reference in the under $1,500 price category. The Njoe Tjoeb comfortably keeps pace with the benchmark performance of the Tjoeb '99, and even surpasses it in a couple of important areas. 

Soundstage clarity and spaciousness, already strong suits of the Tjoeb '99, are slightly more believable. Depth perspective is nicely fleshed out, as are image outlines. The magic of the tube (Oops! That should be tjoeb) in painting a believable soundstage is very much in evidence. The illusion of a 3-D recording space populated by palpable image outlines falls flat on its face even with very expensive solid-state CD players. I've said it before and I'll say it again: tubes constitute a life support system for 16-bit/44.1 kHz PCM digital audio. The notion of listening to standard CD without any tubes in the signal path is a very depressing one indeed. The Tjoeb CD player has clearly shown how to infuse stock mass market players with new life.

The tonal balance is a bit more forward and lively through the midrange, which makes for a more exciting presentation. There is still a tendency toward a brighter-than-life, hi-fi-ish rendition of harmonic textures. This is the sonic equivalent of junk food; it tastes delicious for a few bites, but becomes obnoxious in the long run. I didn't much care for the inherent brightness of the stock tube complement and found it imperative to roll in a smoother sounding tube. Even after a few day of break-in, the JAN Philips failed to mellow out. If I were you, I wouldn't wait that long. Grab hold of the Torx screwdriver accessory and pop the unit's cover off. Oh, be sure to power the player off and disconnect it from its AC outlet before proceeding. My current recommendation is the Amperex Bugle Boy 6922/E88CC premiums available through Richardson Electronics. For about $27 per tube you too can purchase midrange velvet in a bottle. Harmonic textures are sweet and finely layered. The sound is nicely balanced, top-to-bottom, without the upper octave emphasis I so dislike about non-pedigreed 6922 types. The sense of focus and finesse these tubes elicit is well worth the added expense. The Bugle Boys may be purchased from stock and online through the Richardson online electronics catalog. Matched pairs are available, selected for low noise and distortion after a 24-hour aging process.

Outfitted with the Amperex Bugle Boys, the Njoe Tjoeb managed to weave a richly textured harmonic tapestry. And that's AH! is the way I like it: a relaxed, and richly layered presentation. My chronic complaint about the standard CD format is that harmonic textures tend to sound thread bare or coarse. It's a clear case of the nylon stocking syndrome. Stretch the fabric and you can see gaping holes in the fabric. With the Bugle Boys, midrange textural richness increased dramatically and sufficiently in order to enjoy the music.

There's plenty of low-level detail, although this is not an analytical player. Some audiophile players are forever trumpeting inner detail to the point of distraction. If you simply crave detail über alls, then this is not the player for you. However, if you like bass definition and pace, I can report that there's plenty of testosterone in the lower octaves. May be not a 10 on the Richter scale, but easily an 8.

Conclusion

All considered, the Njoe Tjoeb represents a fantastic bargain - a clear 100 on our value for the money scale. Outfitted with the Amperex Bugle Boys, the Njoe Tjoeb remains my reference in the under $1,500 price category. If you're a music lover on a budget, look no further, and treat yourself to this Dutch Bonbon. The old Tjoeb is dead. Long live the Njoe Tjoeb!