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#1
12-31-2006, 11:43 PM
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Speaker Sounds Blown; But Doesn't Look Like It
All,
Making forward progress on my Stewart Warner 11-6V. This evening I played some records on it while it was still on the bench, and the speaker sounded as if it were blown; even at moderate levels any bass would sound like it were coming out of a cone that had a 3 year old child poking holes in it. However, the speaker looks to be in damn near perfect shape. See for yourself: http://farm1.static.flickr.com/133/3...6e345dc7_o.jpg I took some bias readings off of the output tube and rectifier (the two tubes that I replaced), and the output tube reading was about 10-12% higher than spec. Would this have anything to do with the above issue ? Also, here's a quick flick of the Collaro Conquest Changer in action: http://video.google.com/videoplay?do...38811803505246 Thoughts ? Happy New Year !!!!!!!!!!!!!! Steve 
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#3
01-01-2007, 10:30 AM
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What has been done to the amp? Make sure it has all new capacitors. Old capacitors will cause all kinds of problems...
Also the phono cartridge may be deteriorated if it is an original crystal type. This appears to be a field coil type speaker so subbing into another device would be more tough. You will need to patch a PM speaker into the voice coil leads coming from the secondary of the output transformer to do a check.
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#4
01-01-2007, 11:55 AM
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also make sure that the cone moves freely. you can apply light pressure at the edges of the felt dust cap. The cone should move easily. if it does not, the voice coil may be frozen, which would account for the sound.
These can be replaced with permanent magnet speakers, so long as you increase filtering in the audio circuit to get rid of the hum as well as at a resistance load to account for the missing field coil.
__________________
Jordan
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#5
01-01-2007, 12:07 PM
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All,
Thanks for the help ! Sorry, but you are correct; I should have given you all a bit more background.... I just replaced all of the caps and any resistors that were sloppy. Everything works as it should, so I am assuming that my work is fine. I will check to make sure that the coil isn't frozen...Also, maybe you are onto something about the phono cartridge...Im pretty sure it is the original one. Worse comes to worse, I can always unsolder the leads from the OPT and hook them up to another 8ohm speaker just to see what will happen. Thankfully I have the schematic, so I can always find a field coil of the proper spec if I have to replace the speaker. We'll see what happens... Thanks ! Steve
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#6
01-01-2007, 04:42 PM
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Update...
All,
So I pushed on the cone a bit, and it seemed to be slightly 'stuck', so I worked it back and forth. I then give it a whirl; sounded better on AM (quite a bit better), but the phono still was about the same. I then disconnected the speaker and hooked up a spare I had lying around. Alas, it still sounded like poo. So, I suppose a new cartridge is in my future ? Is there any other way to test a cartridge ? Thanks ! Steve
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