Product Review - Castle Inversion 50 Floorstanding Speakers - November, 1999

Daniel Long


Castle Inversion 50 Speakers

Ported Design

One 1 1/4" Cloth Dome Tweeter, One 7" Mid/Bass Driver

MFR: 42 Hz  - 20 kHz

Sensitivity: 88 dB/w/m

Impedance: 8 Ohms Nominal

Size: 36"H x 10"W x 11 1/2"D

Weight: 43 Pounds Each

MSRP: $1,999/Pair USA

Audiophile Systems Ltd. (Castle Acoustics USA Distributor) Website: 


The Inversion 50 represents the middle in the new range of Castle Acoustics loudspeakers. This English company is well known for speakers that combine fine cabinetry with musicality. Among the better known of previous models include the floorstanding Howard and smaller stand-mounted Durham 900. The one that Margil Hi-Fi sent me for review came in beautiful rosewood which, coincidentally, matched my Alon Petite center! The 50s are well-packed in two medium sized boxes with spikes and other accessories in a smaller package inside. This includes the plinth which gives a setup Inversion 50 its character, or look, if you will.


Because the instructions came in only one box, naturally I opened the one without assembly notes first. I took a guess on how to go about it and came very close. You basically open the carton lying on its side and lift the occupant up to stand on its top end. You need to do this so that you can screw the plinth onto the base. It mounts with eight spacers, two at each corner so that the reflex port (only the larger Inversion 100 is Quarter-Wave loaded) gets a firm solid foundation on which to fire into, somewhat like a slot-loaded subwoofer does.

A packing-foam-like material fills the ports. Be careful you don't drop anything into the speaker as you balance the plinth onto the spacers and screw the bolts into the base of the speaker enclosure. I dropped a couple of spacers inside but managed to retrieve them. Don't let your screwdriver fall in, because you wouldn't want to be manhandling a 50 pound loudspeaker to shake it out! Also, watch out when tightening the bolts onto the plinth. You are likely to strip the threads if you aren't careful since it's just wood.


The Inversion 50 is a two way design with a carbon fiber cone incorporating a wet-wound Kapton voice coil, and a soft dome tweeter. The protective grille/netting may be pried open but seeing that they were that way, I listened to them a couple of days without the grilles while they broke in, and then with them in place the rest of my time with the speakers. While I am generally very pleased with the care that Castle puts into each pair of speakers, there are a few things I need to get out of the way before you read what I heard from them. First, the spikes should come with grips/hex-sides for proper tightening; they are long and slim, and it was very difficult to get them into the speaker plinth. And once in, they were practically non-adjustable. I had them in 3/4 of the way, so I could still level the speakers. Murphy was probably at work too because the second pair that were opened in Singapore (the first was on demo at Margil's) had four spike-nuts missing on one side. This didn't affect the performance.


Castle recommends that you bi-wire the Inversion 50s. And unless you have a good reason not to, you should. I used both amps I own, namely a 60wpc Bryston 2B-LP and a 200wpc NAD 218THX. Other equipment included the Lexicon DC-1 (v3.1 with DTS) for digital sources, a Densen Beat-200 preamp for analog with the Rega Planar 3/Grado ZTE-1/Goldring Elektra combo.


A funny thing happened when I first sent music through the Inversion 50s. They sounded forward. There wasn't a noticeable change that evening, but the next day when I put in more time, I found the images moving ever so slightly backwards away from me. As the days went by with more hours of listening, the images settled on a plane somewhat forward (but not as initially so) of the loudspeaker face. There they remained for the duration I had them in-house. While the 50s weren't tall, and I sat almost 102" from them, I expected this would leave me sitting really high to get a decent coherent sound. No such thing. The Castles, despite their slightly over 3' height, threw the soundstage high enough that I could just slouch down into my sofa. And they imaged like devils! While I didn't have to work really hard for them to shine, you can play around with toe-in and see how much suits your listening preferences. I like a wide soundstage, so I had them toed-in to cross, axis-wise, a little behind me. Also, have them not more than 6/6.5' from the listening position if you want a really well fleshed-out center image; having them further apart made for a very spacious soundstage at the slight expense of a hole-in-the-middle effect.


While the 50s was very dynamic, and could easily cope with movie soundtracks given more muscular amplification, they sounded just fine with a low powered amp. In addition, male or female voices had just the right amount of weight and sweetness. While not sounding as seductive as certain other designs I've heard, they certainly were as accurate as my Alons are in reproducing the true timbre of instruments in acoustic music. The voice was very natural and had nothing of the synthetic colorations of some other speakers. I think this has plenty to do with the basic two-way design and the reflex-loaded port, coupled with the heavy and very inert cabinet. On both minimalist recordings (Jacintha) and complex ones (Era), the Castles didn't impart a heaviness that immediately gives away the a reproduction vs. the real thing.

How Low... Did it Go?

On music that plumbs the depths, although you may not get much of the bottom octave, you'll certainly not miss it much unless that's all you listen to. The Eagles' "Hotel California" (Hell Freezes Over) played with enough slam to fill my living room with wave after wave of low frequency percussive tsunami (if you play it loud). While I evaluated the 50s with low frequency music, I also used it for home theater. Can the Inversion 50 be used in such a setting? With a wide range of very dynamic movies including the very, very impressive "Saving Private Ryan", I give it a resounding thumbs-up. While from reputation, the earlier Castle loudspeakers may have been a little polite for home theater, the Inversion series (judging from what I hear with the 50s) are a much different beast. If you have an up-tilted movie soundtrack, that's what you will hear. You will also hear the difference when you switch in a THX circuit that has a roll-off.


The Inversion 50s are a very reasonably priced, very natural sounding, and beautiful to look at (as in high spouse acceptance factor) speaker. For anyone spending up to $2,500/pair, you must give them a listen.

Music Used:

1. Eagles - Hell Freezes Over

2. Space Jam - Original Soundtrack

3. Era - Era

4. DVD - James Taylor Live at the Beacon Theater

5. The Phantom Menace/Star Wars - Episode 1 (Soundtrack)

6. Jacintha - Here's to Ben

7. Tarzan - Original Soundtrack

- Daniel Long -

Copyright 1999 Secrets of Home Theater & High Fidelity
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