Castle Chester crossover protection!

[tubehunter]

Managed to buy these cheap, always liked the 1/4 wave transmission line design.

Sound great, look great. But I had an odd feeling about them.

So decided to check out the crossovers, at first inspection they look pretty good with good quality components.

On a more detailed inspection WHAT the F*** are these thermistors doing in a loudspeaker crossover?
Is this common practice, because I've not seen or heard of them being used as protection devices before.

Anyway after removal the speakers sound much much better.
Just need to keep the volume sensible.

Happy days.

http://i514.photobucket.com/albums/t350/halx00/Castle%20Chester%20crossovers/3196EE59-88EA-4E07-B100-913B4F169757_zpsarff59ix.jpg (http://s514.photobucket.com/user/halx00/media/Castle%20Chester%20crossovers/3196EE59-88EA-4E07-B100-913B4F169757_zpsarff59ix.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/Castle%20Chester%20crossovers/4A70BBC9-247D-4F41-9BCD-4B86DE375D01_zps1ivzvvty.jpg (http://s514.photobucket.com/user/halx00/media/Castle%20Chester%20crossovers/4A70BBC9-247D-4F41-9BCD-4B86DE375D01_zps1ivzvvty.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/Castle%20Chester%20crossovers/8AAA3451-7A10-4E88-96E5-2D98DC343019_zpsjcwfojpv.jpg (http://s514.photobucket.com/user/halx00/media/Castle%20Chester%20crossovers/8AAA3451-7A10-4E88-96E5-2D98DC343019_zpsjcwfojpv.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/Castle%20Chester%20crossovers/056BB424-5CBC-4740-861B-0F88A6DA4A0B_zpsq9jhjfkl.jpg (http://s514.photobucket.com/user/halx00/media/Castle%20Chester%20crossovers/056BB424-5CBC-4740-861B-0F88A6DA4A0B_zpsq9jhjfkl.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/Castle%20Chester%20crossovers/39F18BC6-D3C8-4B30-9BAC-4E83D506846C_zpsmdxob6n9.jpg (http://s514.photobucket.com/user/halx00/media/Castle%20Chester%20crossovers/39F18BC6-D3C8-4B30-9BAC-4E83D506846C_zpsmdxob6n9.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/Castle%20Chester%20crossovers/1B92D579-ED76-4871-90AF-3ED527F8D5C0_zps2dp6mutm.jpg (http://s514.photobucket.com/user/halx00/media/Castle%20Chester%20crossovers/1B92D579-ED76-4871-90AF-3ED527F8D5C0_zps2dp6mutm.jpg.html)
http://i514.photobucket.com/albums/t350/halx00/Castle%20Chester%20crossovers/17106584-4B4D-4C86-82AD-B52D380CDF1A_zpsy4oxwkda.jpg (http://s514.photobucket.com/user/halx00/media/Castle%20Chester%20crossovers/17106584-4B4D-4C86-82AD-B52D380CDF1A_zpsy4oxwkda.jpg.html)

[struth]

Seen them before. Think jbl used them...tweeter protection probably

[danilo]

Curious not seen that use of Thermisistors previously.
These are wonderous gizmos used as inrush current/turn on thump eliminators in an amp
That said, those should be (*when Healthy) 100% transparent.
Castle was a decent maker.
Unlikely those were fitted without reason.
Perhaps buy some brand new ones and see what happens when reinserted?

[Firebottle]

Those are not thermistors as such. They are 'solid state' fuses that go high resistance on overload.

They are there for protection and provided you are careful with the volume level you should be OK without them.

:)

[Reffc]

Had a pair of these from new when they were first introduced in the late 1980's and kept them for many years. Lovely little loudspeakers. Go easy on the volume and avoid the use of low (as in under-powered) amplifiers and they'll be fine. They do benefit from a higher quality series cap on the input to the HF side, and to the second of the series HF caps like for like value.

Crossovers are well designed and use 3rd order electrical HF c/w zobel intended to roll off a rising response with the tweeter. LF is a 2nd order with zobel to flatten a steep rise in impedance with frequency of the midwoofer. Nicely made, and cabinets were also top-notch. HF values should be 4u7 and 13u6 for the series caps.

Note the wiring connections on output. Both should be positive input to positive output (ie tweeter is not reversed) for correct phase.

[tubehunter]

Many thanks for that.

The more I listen to these the more I'm liking.

What higher quality series caps are we talking about , Mundorf , Clarity Cap ?

That 13.6 is an odd value, I'll need 2 6.8uf wired in parallel

Happy Days

[YNWaN]

Wiring caps in parallel is what is commonly done to achieve the correct value. I would remove the protection components completely and replace with solid wire.

I favour Mundorf Supreme for the tweeter but ClarityCap are good (ESA). I see ClarityCap have a couple of new ranges.

Check sizes because the Mundorf, in particular, are quite large.

100% Analogue

[Arkless Electronics]

Those are not thermistors as such. They are 'solid state' fuses that go high resistance on overload.

They are there for protection and provided you are careful with the volume level you should be OK without them.

:)

Indeed they are. They are self re-setting and after cooling down from an over load go back to normal. I would expect them to sound bad!