QuestionQUESTION: I have a old wharfdale speaker whose L-pad(it controls the crosssover) is shot. I want to replace it it is 15ohms(ohm is desiginated by a up side down horseshoe?) if that is correcte then the 15 refers to ohms. Where can I get a replacement or what would work or where can I find out about substututions Thanks so much. Ray Shimels
ANSWER: That is an antiquated design sure to give you trouble. I do not believe that it is part of the crossover. Try replacing it with a fixed 16 ohm resistor rated at a higher wattage then the amplifier you use to drive the speaker. The windings of an L pad eventually burn out. That is why most volume controls currently used are transformers with multiple fixed taps which act as an attenuator and work like a volume control.
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QUESTION: the L-pad controls the volume of the tweeter there is also one that controls the volume of the midrange it may be antiquated but it sure sounds a lot better than most of the high end speakers on the market today I can hook it up direct, as you have suggested but the beauty of the design is the ability to adjust the levels of the tweter and midrange any other thoughts?
ANSWER: I have been in the audio recording and mastering business well before the Wharfdale speakers were made. As somewhat of a purest working in mastering labs and working with Mark Levinson I can tell you that as good as they may sound to you the science of power loss though passive resistive networks are not in the realm of transducers that I would consider superior in quality. These days the only tweeters that I find that accurately reproduce sound with forgiving qualities in anechoic rooms to hostile acoustic environments are ribbon tweeters. Their sound field accurately portrays imaging representative of the original room where the recording was made.. Having said that any transducer as old as a Wharfdale cannot possibly have transducers in it that have retained a cylinderical voice coil or have not fatigued because of the paper cone that typically was used 30 plus years ago. I will be more than happy to recommend something that would out perform that speaker but cannot honestly recommend any repair other than tinkering with ad hoc parts since the company has not been in business for decades. Speakers that I use in my work are crossed over electronically and are all planar using four pistons per driver to accurately propagate sound. I may not be the person you want to ask if your a hobbyist.
http://en.wikipedia.org/wiki/L_pad
Incidentally, a correctly designed speaker should not need or have adjustable power balance. With CADD programs today, cabinet resonance, time aligning, crossover points and transient response, change radically as one changes the amplitude of the drivers. If you haven't heard a speaker that makes you happy then your probably not listening to the really good ones. See if you can find a used pair of Red Rose speakers.
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QUESTION: Thank you for your information. I wish I could justify spending money on a set of superior speakers. Alas, I must make do with what I can scrounge. One last question Do you or could you tell me what I could get away with as far as installing a potentiometer in place of the old one I erealize I am"tinkering" but this is all I can do I am not in a position to make a major purchase at this point Thanks for giving me your valuable time Ray Shimels
AnswerThat's one of the reasons I sent you a link to the wikipedia L Pad. The maximum resistance will probably be only 16 ohms. You don't want to place a short accross the amplifier, so I would follow some of the examples of resistive networks. There may be a manufacturer on line who sells an L Pad with examples. If not just pull out an old audio book from the 60's from the library or on line. There are many manufacturers that you can still buy these things from (search L Pad)just try and get one that is a high enough wattage so it doesn't burn out right away.
