77Eric

Hi again... After listening to my RB-5's for a (short) while after my internal jumper fix I concluded that they still didn't even come close my expectations (based on internet talk along with my experience with my Cornwalls). I probably fooled myself in my previous tests, or maybe my fix helped a little but didn't really solve the problem. Back to the drawing board... The next thing I looked into was replacing the tweeters. Turns out replacement K-105-K Ti tweeter diaphragms are only $20 each so I ordered a couple from Analog Classics. Installing them is easy enough as there's no soldering, just simple nuts and bolts and crimp connectors. No need to even disconnect the speakers - just pull the tweeters out the fronts, replace the diaphragms, and put them back in. I measured the DC resistance of both sets of diaphragms and while the originals were 3.4 Ohms the replacements were about 5.8 Ohms. Initial listening tests were astounding! My speakers went from boring and lifeless to dynamic, musical and 3D! My toes were tapping! I'm not talking about a subtle change, either - this was a complete transformation. It's been a week or so of listening now and they still sound great! I finally am hearing what got these speakers their reputation. The obvious conclusion is that my original tweeters were not performing up to snuff (as I suspected from the get-go) but since the new ones look and measure differently I suppose it's possible that I just did a tweeter "upgrade". I don't really think that's the case, though, and I'd be interested to know if good original tweeters measure around 6 Ohms like the replacements did. Eric

Hi, I tried hooking up one of my RB-5's biwired and it sounded much better so that indicated to me that maybe the external jumpers aren't making good contact, or perhaps something else is amiss with the connectors. Since I just plan to use conventional wiring I went ahead and soldered in some internal jumpers using some thick copper wire I happened to have rather than trying to further debug the connectors. I put the speakers back in my system and have done a bit more listening and they certainly seem much improved. One theory I have is that perhaps these speakers sat in storage for a long time and the connectors got tarnished a bit or maybe the speakers just need to get broken in again? Also I believe there is a period of adaptation in terms of how I perceive the sound so perhaps just using them and tweaking my setup a bit will really get them all the way dialed in. They already are a big change for the better, though, so I'm looking forward to seeing how good I can make them sound. Eric

Hi all, Thanks for the responses and welcomes. I used to hang around here but I couldn't find my old account or maybe I was just a lurker so I'm limited to 1 post/day for now. I looked at it some more last night and I've come to the conclusion that there's nothing obviously wrong. I verified the jumpers are working correctly, and I guess the "transistor radio" effect when running the tweeter through the crossover (jumpers removed) is maybe OK since the crossover is at 1950Hz. The reason I went through this investigation was because of the rolled off treble which led me to check the tweeter resistance at the speaker inputs (jumpers removed). It was open and that threw me off. Looking at the crossover schematic, though, this is what one would expect (high pass filter won't pass DC). I will try running the speakers biwired so I can control the tweeter/woofer inputs independently and maybe try biamping as well. I'll report back... Eric

Hi, I've been searching for a pair of black RB-5's for a while now so when a pair showed up locally on CL I bought them, brought them home, hooked them up and was underwhelmed. It didn't take too long for me to realize that the tweeters (K-105-K) on both speakers didn't seem to be working right. I disconnected the biamping bars and the tweeters measured open (infinite resistance) and in a brief listening test made sound but akin to a little transistor radio. Pulled a tweeter on one speaker and it measured around 3.4 Ohms and hooking it up directly (no crossover) yielded reasonable sounds so I conclude the problem is not the tweeter. The next easy test was the 4 Ohm 10 Watt resistor on the crossover board. It measures 4 Ohms so that doesn't appear to be the problem. At this point I thought it best to ask for advice on my next moves. Am I missing something here? Any other tests I should do? Should I start looking for some replacement crossovers (116436)? Eric (longtime happy Cornwall II owner)