Tweaking Castle Conway 3 speakers

[Richard]

I got a pair of these used a few months ago after reading very positive reviews from Noel at HFW and thinking they should work well in our room.

http://www.castle.uk.com/LinkClick.a...language=en-US

I must say I agree completely with the review. A flawed gem of a speaker.

I lived with it and it educated my ears to a different presentation. I still missed a little air and sparkle at the top end though.

First job was to try the spikes. The mounting inserts were loose in the MDF plinths so I'd not used them yet. They wobbled and rotated but wouldn't pull out by hand. To stop the insert pulling the MDF to pieces around the hole I put a large washer on first, with a hole just large enough for the insert, then stacked more washers and used the spike nut and thread to draw the insert out with a spanner. Refitted them with epoxy and they work properly now.

That tightened up and focussed the sound and was well worth the effort but Noel's measurements and my ears said I should look at the crossover.

It came out easily, just up-ended the speaker, undid the 8 screws on the terminal panel, and there it is on the back. Very high quality parts for a commercial design. So are the drivers and cabs too.

Followed the circuit and drew it out below. It's clear to see the 3R3 attenuating resistor for the tweeter on the left in the pic connected directly to one end of the 4.7uF.

Did the maths and figured that for a nominal 8 ohms 3R3 gave -3dB to the tweeter. Changing that to 1R2 would give -1.2dB or using 2R2 would give -2.1dB. So those changes would effectively raise the tweeter level by approx +2dB or +1dB.

That didn't sound much so I plumped for the +2dB raise and fitted 1R2. It was immediately noticable but after a couple of tracks all I could focus on was the new found treble! There were no nasties with it and it didn't seem to be showing up limitations in the tweeter but it was just too detached and unrealistic sounding.

Then went for the 2R2 which should only raise level by 1dB so didn't expect much but it is fantastic! I cannot believe that such a small change has improved the sound to this degree. Still transparent and natural but with the air and presense that was previously lacking. Not just a sound balance thing either as there is now much better soundstaging, presumably as so much directional information comes from the high frequencies.

Anyway I realise there won't be millions of these speakers out there but here are the pics,