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Review of Ah! 4000 CDP w Upsampling Board (Long) (1 Viewer)


Feb 11, 2001
Table of Contents

Schematic of System
Initial Impressions
More Impressions


I have been an owner of the Ah! Njoe Tjoeb 4000 CD player for over a year. My system was finally in a position to make best use of the TjoUpsampler 24 bit / 192 kHz upsampling board that became available for this unit (from Upscale Audio, of course) approx. last September. Being swept into the fever to continuously upgrade, I ordered the board, and it has been in my player since early April.

Before I get into the review, the usual disclaimers apply: reviewing audio components is not a pastime for me, I have no golden ear (got back into music within the last 2 years after a long hiatus), and I have little experience with other components. I do have a Sony CDP which was very helpful for comparison purposes, though.

As any Ah! 4000 owner knows, just saying that I have an Ah! 4000 is insufficient to properly identify it. The upsampling board is just one of the tweaks that can differentiate specific instances of the unit. The other aspects of my Ah! include the following:

Amperex 7308 tubes
Upgraded AC cord
Upgraded Digital output (which I don't use)

My HT/audio equipment list can be viewed via my signature link. However, probably more useful is the schematic below of the reviewed 2 channel portion of the system, which includes the Sony SCD C555ES SACD changer.

An apparently popular upgrade to the stock 6922 tubes of the Ah! are the Siemens 7308 tubes. At the time of purchase, Kevin Deal of Upscale Audio suggested that the Amperex version of these tubes would provide for a warmer sound, which is what I was looking for as a potentially better complement to my ribbon-based speakers. I do not recall if Kevin mentioned any other differences between the Amperex tubes and the Siemens, though. To this point, I have used the Amperex tubes exclusively.


After delivery of the upsampling board, I listened to the Ah! one last time prior to board installation (note that I compared the Ah! with the '555ES a couple of weeks prior to receiving the upsampling board; I finally had common interconnects!). After installation, I listened to the board immediately to get an initial impression. Then I played music with the Ah! for the better part of the next 100 hours at low to moderate volumes to provide some break-in, in case the board needed it (and to remove a potential variable from the review equation). Thereafter, I used the Ah! sporadically for the next 2+ weeks. When not in use, I leave the Ah! in standby mode. I calibrated the output volume of the Ah! to roughly match the '555ES using test tones of various frequencies, measured with a Radio Shack SPL meter.

A word about using a sub

Due to the characteristics of my listening room, I needed to equalize the bass frequencies. As such, I use the Outlaw ICBM to peel off the frequencies below 80Hz and send to the sub via the BFD. I have not noticed any degradation in 2 channel audio as a result of the ICBM in the path, and I am very happy to have a fairly smooth freq response down low, not to mention one for which the volume can be adjusted independently from the rest of the spectrum.

Initial Impressions

My first take on the effect of the upsampling board was a noticeable improvement in the detail of many instruments, typically towards the higher end of the frequency scale, such as some guitars, cymbals, and some brass instruments. At the same time, I thought that some of the warmth was lost in the process, probably a necessary trade-off to the additional detail and clarity. Of more concern to me was the possibility that some of the oomph that I heard in lower frequencies would be lost, as well as some of the fullness in the midrange. This impression was based on the short listening session I had just after installing the board. This judgment was in comparison to a couple of selections to which I listened about 2 hours prior on the Ah! without the upsampler.

More Impressions

That first impression was short and based on comparison to the pre-upsampler Ah!. I did no more critical reviewing for 3 weeks or so, as I mentioned in the Preparation section. The in-depth impressions I describe in this section are based on pre-upsampler and post-upsampler redbook comparisons with the '555ES, as the '555ES remained constant in the system. As the schematic shows, the connectivity and components downstream from the '555ES match those of the Ah!, creating a good basis of comparison, IMO.

In the pre-upsampler mode, the Ah! was noticeably less detailed than the '555ES in the upper frequency range. For example, cymbals were typically rolled off with the Ah!, at least in comparison with the '555ES. However, I wouldn't call the Ah! muddy, either. Without the '555ES for comparison, one may not think that the Ah! was rolled off or particularly warm, especially on my Soundline ribbons. Additional evidence was heard with other instruments, such as the horns typical with Chicago's music. I like to use the first Chicago album (Chicago Transit Authority, 2002 Rhino remaster) as a barometer of just how harsh the highs can sound. When played at the maximum volume at which I like to play CDs in general, the sound of the horns, cymbals, etc., at the end of Questions 67 and 68 and Beginnings can be ear-splittingly shrill to me. The pre-upsampler Ah! was tame enough with this selection to make it marginally listenable. The '555ES was instantly unlistenable at this volume.

With the upsampler board, the Ah! was much closer to the '555ES in detail. In the aforementioned Chicago selections, the Ah! was also instantly unlistenable. Of course, this selection is an extreme case. The earlier sections of Questions 67 and 68 are not quite as extreme up top, and both units exhibited similar amounts of enjoyable detail. In general, both units were very similar in terms of detail with other material towards the high end of the audible freq spectrum.

As for the midrange frequencies, my impression of the Ah! compared favorably to the '555ES in terms of fullness and presence. For example, the saxophone in Spyro Gyra's Morning Dance (from the album of the same title) seemed to have extra height on the Ah! compared to the '555ES. It also seemed to be "heavier", in the sense that it appeared to take up more space (sort of like a larger soundstage). I got this same impression from the redbook layer of the Stones' Beggar's Banquet hybrid SACD disc. The acoustic guitar in songs such as No Expectations, Dear Doctor, and Factory Girl again had a richer, fuller sound to them on the Ah!. This is an impression that would have gone unnoticed to me without a critical comparison between the units, however.

Ah (pun intended), but my impressions of the pre-upsampler Ah! with these selections was the same relative to the '555ES as the Ah! with the upsampler was. Thus, it does not appear that the upsampler had much, if any effect. Something else associated with the Ah! is likely responsible. Maybe it's a whole slew of items. Alternatively, maybe the Amperex tubes play an integral part in this distinction.

Getting down into the lower registers, the Ah! had noticeably more oomph than the '555ES (both with and without the upsampler). Name your tune, and the Ah! delivered with more authority and definition down low. On the title track of Steely Dan's Aja, the drum sequences near the end simply had more force and distinction. The same can be said for the bass from Black Cow on the same album. I did find that at some point, the difference between the Ah! and '555ES in this area diminished, typically with selections that were naturally very strong in bass (yes, stronger than Black Cow). Case in point: The Rippington's Curves Ahead (from the album of the same name); the bass is very strong in this song and was delivered about equally well by both units.

Again, the upsampler made no difference that I could discern down low, which is not surprising to me. My guess is that the Amperex 7308 tubes probably have this added impact at the lower frequencies as well as into the midrange. I'd be curious if someone else has these tubes and can relate similar experiences.

Is that it?

Not quite. Throughout, there seemed to be a difference in sonic character between the Ah! with upsampler and the '555ES that goes beyond the differences described above and that always seemed to be present. I couldn't pinpoint this difference early on, but it sounded almost like the '555ES had a cleaner sound, or that the noise floor was lower. I finally was able to localize this distinction a bit better. When listening to the piano notes that begin Supertramp's Lord is it Mine (from Breakfast in America), it did sound as if each strike of the piano keys was coming from a darker, more quiet place with the '555ES than the Ah!. Not sure I can explain it any better than this. Maybe each note lingered a bit longer with the Ah!, resulting in some audible "collision" with the succeeding note. Maybe it was something else. I couldn't isolate this effect any further; suffice it to say that their sonic signatures had this difference to my ears. Again, it's not an attribute that I perceive well outside the mode of critical comparison.


The Ah! Njoe Tjoeb 4000 with the upsampling board is a noticeable improvement in detail and clarity in the higher frequencies relative to the Ah! without the upsampling board. There was probably some loss of warmth in this frequency range (a natural trade-off, IMO), but it did not sound like any of the warmth and fullness of the mids, nor bass definition and slam, were lost in the process. This improvement makes listening to redbook audio more enjoyable overall. As such, the Ah! with the upsampler makes for a compelling choice for many redbook selections relative to the Sony SCD C555ES. The trade-off to my ears is the Ah! added value I described in the mids and lows versus the cleaner sonic signature of the '555ES. Note, however, that many of these distinctions do not come out and slap me in the face, except when doing a critical comparison. The only area that is readily different between the two without concentrating is the bass definition advantage of the Ah!. It is quite possible that the Amperex 7308 tubes play an important role in these Ah! characteristics.

Given that the '555ES is a 5 disc changer and supports SACD, it continues to get its share of work in my system. There is no doubt, though, that I am listening to the Ah! more than before. It seems to be quite a good match now for my Soundline mains. Plus, there's always more tweakability with the Ah! via other tubes to satisfy the never-ending urge to upgrade.



Senior HTF Member
Mar 28, 2000
Doug, thanks for the excellent review. Interesting observations. As you know, I sold the Ah! before getting the upsampler because I thought the 'C555ES bested it in every way in my system. Perhaps the upsampler would have made a difference, but I can't say I have miss the Ah! now. You still have me curious, though. :)

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