damping (BD-Design)

by GC, Thursday, August 04, 2005, 22:34 (6811 days ago)

Hello Bert,

I reported on finishing my BD-15 cabinets about one month ago. So by now breaking in of the units should be finished. Recently I played around with the amount and the position of the damping material (stiff plastic foam with rather open structure, it has a mixture of colors). I measured the impedance characteristic and found two maxima, at 21 and 67 Hz. The first one is 110 Ohm, the second one 185 Ohm and the minima are 15 Ohm. These values hardly changed during all changes, and also there were practically no differences in sound. In the past I used a few times far too much damping material. Am I too carefull now? I must add, nevertheless, that the sound is becoming very convincing by now. Speed and attack of bass drums and guitars are really getting to something that reminds of real instruments and that is indeed a big difference with all my previous bass speakers. Real deep bass is not available, the lowest audible frequency is somewhere just below 40 Hz. This is almost never a miss and the increase in clarity is much more important.

My TwinDac is also getting into shape. The first evenings I listened to it I was quite disappointed by the flat and uninvolved sound it produced. Only the bass sounded more detailed than from my Theta D/A converter. (This 15 year old converter probably suffers from worn-out capacitors in its power supply.) To my surprise the sound became gradually better and by now beats the Theta in all respects, even the width and the precision of the sound stage. Any idea what changes I can expect from replacing my CD-transport with a laptop?

The only problem remaining is the hum in my amplifiers. I tried many things with cables, grounding, shielding etc. Two days ago I suddenly got into a situation where this hum is inaudible at the listening position so for the moment I stopped to find the cause and I am enjoying many new details on old CDs.

Best wishes,
Eddie

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