Jeff Rowland Model 501 - Help ...

Dejanm - As far as I know tweeter has very high impedance at 0.5MHz therefore power delivered will be very low. In addition there should be no intermodulation products because membrane cannot move at these frequencies.

I promised to provide a feedback from a friend who tested these Jeff Rowlands ... so here it is ...

He installed JR Model 501 monos in a system where Primare was a preamp and the speakers are Harbeth. CRT TV was about 20 cm away from monos (they were put one on another) and the FM tuner was somewhere about 80 cm away from these monos. Power cords of these monos were plugged into separate wall mains from the rest of the system.

He could hear a brum on all radio stations (cable network reception) and the picture on some (not all) TV stations was clearly degraded. It is a clear evidence of some, not negligible, radiation from these units.

Therefore I decided not to go after these babies although, as I already mentioned, the offer is really good one. That is pity, because I know that they can produce, with the right speakers, excellent sound reproduction.

I wish to thank to you ALL for your advices and comments ...

The latest Bel Cantos have a filter that keeps out the Class D generated interference.

I'm very skeptical of these results. I have a Rowland Capri preamp and 102 amp stacked next to my Kenwood KT-917 tuner and sitting beneath a Panasonic plasma TV, which hangs on the wall above and behind. The amp is 7 inches from the tuner and about 18 inches from the TV. There is no indication whatsoever of interference or noise. I'm using the Rowland 102 to power a pair of 108 db efficient horns so I'm sure the noise would be obvious if it existed.

@Macrojack

It is very difficult to find out the truth in HiFi ... in general. For example: you have different JR units (which are as far as I remember the later models) and completely different TV technology. FM is though the same.

I had for example the opportunity to talk to Jeff Rowland on Muenchen HiFi show, two weeks ago. And I asked him explicitely about radiation of 501's and he told me that they are safe concerning that matter. He told me even that JR has in their testing room an FM tuner placed on these mono's and that there are no degradation of FM signal.

I have no reason not to believe Jeff Rowland but friend of mine does not have any reason not to tell me the truth. He will though repeat the test in a completely different system (another friend of ours will be involved).

The only conclusion is that the radiation might be, under certain circumstances, an issue, depending probably on many factors. But that risk is to high for me ...