Canton CT-1000/2 three way loudspeakers. Apr 2024 I heard a pair of these at a local HiFi meeting and fell in love with them. Overall, I would say they are slightly better than my Yamaha NS-1000m for home listening. They have a more relaxed presentation, which is easier on the ear, they go much deeper in the bass than the Yams and have a more fleshed out midrange, with a less forward treble. As such, they are more Amp friendly, the Yams being notoriously picky when being partnered with Amplifiers. They are pretty rare in the UK, having been manufactured in West Germany, that's still where most examples can be found, though many seem to have found their way behind the old Iron Curtain. I purchased a pair that were advertised in Germany, they were without boxes and pick up only. I found a local company that would pick them up, pack them, then ship them to the UK. The ones I bought were the later second series and the premium version with Piano Gloss, Mahogany cabinets. The original series had the Mid-range and Tweeter drivers mounted side by side, the mid range had a rear vented chamber and the input terminals were spring loaded. The second series had the tweeter mounted above the mid range and no vent at the rear. The spring terminals were replaced with proper binding posts. Both used the same 12" bass driver in a sealed cabinet of the same volume.  A few shots of mine below, which don't do the finish justice. For items made in roughly 1986, they have been very well looked after.        Speaker Stands I need to make some stands for these speakers, I want my Monoblock Amps to sit under each speaker. So with this in mind, I thought along the lines illustrated below.  So on with the build.......  I built the stands, like a chair or stool, using 45 x 70 rectangular timber fixed with 12mm dowels and using larger 25mm dowels as cross rails.  No fixings used, just glue and clamp up.  I made the front and back frames first as sub assemblies, all the rough finishing and truing up was done at this stage. M8 Threaded inserts were fitted to the legs, to accept floor spikes.  Final assembly and more 25mm dowels were used for the rails between the front and back frames. Just a final rub down with fine sand paper and they're ready for the finish.  Ebony Black wood stain was applied as an undercoat, then x2 coates of Satin Black Acrylic paint, applied with a brush and roller.  One of the speakers on its stand, with the 600mm Atlas Hyper Bi-Wire speaker cable I made up to connect to the Amp.  My Neurochrome 686 Monoblocks sit between the legs of the stands and they look well together, I need to get some hours on this set up as the Amps and leads are brand new. Transit Cases I need to make some transit boxes to protect the beautiful gloss finish on these speakers. Thinking along the lines of packing cases I got some panels of 5mm Ply cut at B&Q (measures 4.2mm). I applied soft wood edging of 19 x 38mm sawn timber, purchased from Wickes. It measures 16 x 36mm! For the base, Wickes supplied 9mm Ply (measures 8.6mm) Foam of 15mm thickness for the sides and 20mm for the bottom was ordered from T.K.T. Cosyfoam (Washington UK). Tip: cut foam with an electric reciprocating carving knife.  These are the x8 panels I made, ready for assembly.  Glued, screwed, panels and bases. A coat of sanding sealer and mat varnish applied. Ready for the foam lining.  Thats the boxes finished with one of the speakers installed, they fit, phew! Crossover The speakers are nearly 40 years old, the electrolytic capacitors in the crossovers will most likely be out of spec. I decided to refresh some of the parts and take the opportunity, to improve the quality of the Tweeter series cap and resistor. I've kept the original boards and inductors, but upgraded the ceramic resistors. The Tweeter had a Polyester film cap originally, so replacing that with a modern Polypropylene film cap wont alter the speakers character. The electrolytic caps will be replaced with similar electrolytics. I found out the hard way, you can't just drop in a film cap as an upgrade for these, as they have different resistance characteristics. ESR values change with frequency, low frequencies generating much higher resistance. Also smaller capacitance values have higher ESR than larger ones. You also can't drop a fixed resistor in series with a film cap to simulate higher ESR, as the resistor will effect the whole frequency range equally, where as Electrolytic ESR is variable with frequency. In some instances, a straight swap to a film cap might be a fluke improvement, my experience is that in most cases, it will just sound different. Manly because the frequency curve will have altered from the original. If the circuit was designed using the characteristics of electrolytics and you like the way it sounds, keep to electrolytics. Putting a better part in, with different characteristics will sound different, but probably not better. Many folks who rave about their expensive new XO upgrades, end up selling the speakers quite quickly, having lost the magic that they liked in the first place. I got the T shirt for that one in the past.  This is the crossover in my later version CT 1000's.  The single Polyester Film Cap (Tweeter series cap) is in the bottom left corner, the rest are electrolytics.  Here is the crossover with the new parts fitted. I went for the Mundorf E-Cap Bipolar Electrolytics as replacements. Comparison of Old and New C3 cap measurements. Very similar results. You can see that ESR is 2ohms higher at 120Hz than at 1kHz by the time you get down to 30Hz the increase in ESR can be tens of ohms.  Measured Caps and Resistor Values (Right hand speaker)
(Target) Old
New
C1 (120uF) 145.9 120.7 Mundorf ECap Raw Electrolytic 35V C2 (47uF) 51.72 47.45 Mundorf ECap Plain Electrolytic 70V C3 (15uF) 16.22 15.00 Mundorf ECap Plain Electrolytic 70V C4 (4.7uF) 4.601 4.776 Obbligato Copper Series Poypropylene 630V R1 (1.5ohm) 1.479 1.501 Jantzen 10W Superes R2 (47ohm) 46.17 46.84 Jantzen 10W Superes R3 (1.8ohm) 1.759 1.784 Mills MRA 12W R4 (0.27ohm) 0.2547 0.2672 Mills MRA 05W Inductor Measurements (Target) Measured L1 (3.27mH) 3.325 0.6347 DCR L2 (0.4mH) 0.4316 0.6350 DCR L3 (2.35mH) 2.474 0.3791 DCR L4 (0.26mh) 0.2857 0.1435 DCR I was surprised that the caps were still in spec (if +/- 25% had been the rating). I used 5% replacement caps and matched pairs much more closely than that, as the measurements above show. For the Tweeter, I chose to replace the basic Polyester film cap (C4), which lies in the signal path, for an Obbligato Copper Series Polypropylene. These have a reputation of having a clean and open top end, ideal for a Tweeter filter. The ceramic resistor (R4) also in the Tweeters signal path, was replaced with a Mills wire wound, non inductive +/- 1%.  The basic White metal binding posts where changed, to Laboratory grade Hirschmann 35Amp banana sockets. These mounted nicely on the existing plate.  The internal wiring has also been improved. I fitted Atlas Hyper 2.0 speaker cable, from the posts to X-Over and from X-Over to Bass Driver. The Midrange and Tweeter drivers were connected with Atlas Hyper 1.5. These cables use high purity copper covered in Teflon and are my go-to speaker cables, I use the same cable inside the cabinet as I do from amp to speaker, I just scale down the thickness slightly for these short internal runs. What about the Sound! I gave it 150 hours play before giving a serious listen. Things were generally cleaner, top end clearer, better defined and bass was deeper with more texture. Was I happy - No! The response was "V" shaped, midrange recessed slightly, a bit of grain in the upper mids and tonally just not right. It's not really noticeable on instruments, but vocals don't sound right, certain artists don't sound like I remember them, the vocal sounds thin and slightly higher pitched. I couldn't live with this, so it needs attention. The replacement Mundorf ECap Lytics just sound different to the original Lytic caps. I looked at the caps I had taken out. The two parallel electrolytic caps (C1 & C3) are in Red jackets, but C2, the series mid range cap, is in a Yellow jacket. The Red ones are low ESR, but the 47uF Yellow measures with VERY low ESR, almost into PP film territory. This Yellow Lytic, being in series with the mid driver, will have a major impact on its sound. It seems to have been something special and the ECap (plain) I used, just wasn't performing the same, so things need a re think. I dummied up 47uF with 3 Mundorf MKP's out of my parts bin and sure enough, their combined ESR level throughout the mid range frequencies, was closer than 0.5ohm to the original Lytic. So contrary to what I was saying earlier, about ESR incompatibility, in this instance, for the frequency band used, a PP film cap can be dropped in as a direct replacement for this very low ESR electrolytic. I looked at what was available in this large 47uF value and there's not a lot of choice, price and physical size become an issue. I eventually settled on the ClarityCap CSA PP Film cap.  These are what I ordered, they measured close to the 47uF target value, each other and were considerably better than the +/- 3% stated. At 58mm Dia x 50mm length, its going to be tricky, mounting these.  This is how the ClarityCap measures, compared to the original Electrolytic. In the required 450Hz to 3100Hz (crossover band pass) range, if you extrapolate from the measurements above, there is only around 0.2ohm difference in ESR between the two. The difference being largest at the low frequency end, all things considered, a very good match.  This is one of the caps fitted. While I was at it, I swapped out R2 the 47ohm Jantzen Superes, for a mills MRA12. This resistor is paralleled across the C2 cap. I find the Mills MRA a bit smoother than the Jantzen Superes resistors. So these were my attempts to smooth the upper mids, correct the tonality and give the mids a bit more presence. I gave them a similar settling period, before evaluating the results. Sound After 150 hours of playing. Ahhhhhh! That's so much better, back to the tonality I remembered. To be honest, this is now more than a refresh, its an upgrade, the sound is cleaner and more detailed throughout. Not a hint of sibilance and comes out of a Blacker background. It's not cold or fatiguing and still has the richness and even presentation I love about them. I'm just loving listening to them, I would recommend this final parts choice to anyone looking to refresh and extend the life of these loudspeakers. That's it for Speakers, These will probably see me out now, my keepers. Final Cap and Resistor choice
(Target) Parts Used and measurements (Right hand Speaker)
C1 (120uF) 120.7 Mundorf ECap Raw Electrolytic 35V C2 (47uF) 46.59 ClarityCap CSA Polypropylene 250V C3 (15uF) 15.00 Mundorf ECap Plain Electrolytic 70V C4 (4.7uF) 4.776 Obbligato Copper Series Poypropylene 630V R1 (1.5ohm) 1.501 Jantzen 10W Superes R2 (47ohm) 47.08 Mills MRA 12W R3 (1.8ohm) 1.784 Mills MRA 12W R4 (0.27ohm) 0.2672 Mills MRA 05W |
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