Cambridge Audio R40 - Crossover Help

[1gadget1]

Crossover Help

Hi all,

I’ve just sold my Dynaudio Floorstanders and got some R40’s with a plan to upgrade the mid, tweeter and crossover with the left over cash.

Spanner in the works: I like the sound the R40’s produce much more than I had anticipated. So thinking maybe just do a crossover upgrade.

Upon researching/browsing the forums I’m getting mixed opinions: some saying just buy the preassembled Falcon XO’s, some saying the Wilmslow ones are better but bigger and don’t fit inside the enclosure and I’m surprised that no one suggested using air core inductors and MKP caps.

I’m not fussed about the XO’s fitting inside the enclosure(I’m quite happy to house them externally) I’m more concerned about achieving the best sound possible from the original drivers. I won’t be spending Mundorf Supreme silver/gold/oil figures but am happy to spend a couple hundred quid on building decent XO’s. Opinions Welcome.

Also I’ve come across two circuit diagrams: the original R40 (R50 without the super tweeter section) and the Radford Kef Concerto XO of which looks quite different but is for the same drivers (Kef b139, b110, T27).

Is one better than the other? If so, why?

Like I said before, I really like the sound of the R40’s, but I know they have never been opened and therefore are probably due new caps at least. But while they’re open I may as well do all I can to get them sounding the best they can.

All input will be much appreciated

 

[rayma]

I really like the sound of the R40’s, but I know they have never been opened
and therefore are probably due new caps at least.

Here's the crossover (less the top tweeter). Many or all will be bipolar electrolytic types,
so replace those at a minimum, but film caps may not fit. Check the 10 ohm resistor
for value and overheating. http://i65.tinypic.com/2u5s1av.jpg

 

[1gadget1]

Here's the crossover (less the top tweeter). Many or all will be bipolar electrolytic types,
so replace those at a minimum, but film caps may not fit. Check the 10 ohm resistor
for value and overheating. http://i65.tinypic.com/2u5s1av.jpg

Thanks for your input.

As explained I’m most like going to house the XO’s externally so the size of inductors and caps isn’t an issue.

 

[1gadget1]

I’ve emailed Falcon Acoustics for some advice, but they’re away at the High End Show in Munich at the moment. Was hoping for some unbiased input from you forum members though.

 

[1gadget1]

So Falcon got back to me with some good advice, particularly about cap esr and inductor resistance when switching to mkp’s and air cores. Still unsure whether this route will give me better results though, no one I’ve spoke to has had a definitive answer.

 

[picowallspeaker]

Do it

The usual value scaling doesn't correspond to the standard values
For example 5 and 30 uF, some brands make them ( Dayton ? )
...but 4.7 and 33 uF might be ok 😕

 

[system7]

I would be inclined to listen to Falcon Acoustics on a speaker that they are familiar with.

I know this one too, having tidied up the old KEF Concerto and TDL80 speakers.

In my experience, old NP electrolytics just go on and on. This Wharfedale Shelton XP2 speaker is pretty old, but still sounds near faultless to me.

Replace like with like, if you need to. That probably means 50V NP Alcap types. The ESR plays a part in the overall design, and MKPs might sound brighter. Air coils shouldn't really make a huge difference, IMO. A speaker is just one big ferrite coil itself... 😀

I think I prefer the Cambridge R40 implementation to the KEF Concerto. Impedance correction on the mid must help. But hardly a smidge between the two. The supertweeter is no bad thing either, but my battered old ears probably wouldn't hear it. 😱