intrique45 Posted January 8, 2020 Report Share Posted January 8, 2020 Hello new member to this forum. I would like to ask for some help. I have a NAD 7140 receiver and two pairs of Allison 7 speakers. One set is the CD-7 series used for the back channel (B) All owned since new. I had no problems with these with the receiver but came upon a problem when i switched the CD7 to be the main speakers and the regular Allison 7 to the back speakers (B) While playing a cd on my Parasound cd player on moderate volume the CD7 speakers started to distort and lose volume on both speakers the back speakers were fine. I checked all wiring and all ok. I turned off the receiver and tried playing the cd and the receiver did the same thing after a a few minutes Strange thing is I then changed the CD7 to the B side and the regular Allison & to the front (A) Problem went away. With this setup I can play all day at high volume without any problems Could it be the caps in the CD7 creating the problem? The crossover in the CD7 is different. It has two coils and a small blue resister? Any recommendations on replacement caps for both crossovers? Quote Link to comment Share on other sites More sharing options...
newandold Posted January 9, 2020 Report Share Posted January 9, 2020 Highly unlikely the capacitors in the Allisons are causing your problems. The resistors in the CD7s are internal, thermal overload protection for the drivers and I’ve heard of instances of them going bad. You could bypass them and be careful of overdrivng the speakers but leave the original caps alone Quote Link to comment Share on other sites More sharing options...
intrique45 Posted January 9, 2020 Author Report Share Posted January 9, 2020 Hi thanks for your input My concern is that there are no problems with the CD7 in the back channel I guess the B channel may get less wattage then the A channel so they dont clip? I just played two CD s for about an hour at moderate to loud volume and no problems with any speaker. Thats why I lean toward s the CD7 Maybe the ferrofuid in the tweeters are dried up or the cap is dried up and when under a high wattage load it creates the clipping?? Quote Link to comment Share on other sites More sharing options...
newandold Posted January 9, 2020 Report Share Posted January 9, 2020 2 hours ago, intrique45 said: Hi thanks for your input My concern is that there are no problems with the CD7 in the back channel I guess the B channel may get less wattage then the A channel so they dont clip? I just played two CD s for about an hour at moderate to loud volume and no problems with any speaker. Thats why I lean toward s the CD7 Maybe the ferrofuid in the tweeters are dried up or the cap is dried up and when under a high wattage load it creates the clipping?? "The NAD design principles recognize that the minimum impedance of most speakers is somewhat lower than their nominal ratings. It is not uncommon for the impedance of a "4-ohm" speaker to fall as low as 2.5 ohms at some frequencies. If two sets of such speakers are operated in parallel, an amplifier with limited current capability may produce distorted sound or even overheat and shut down under prolonged or high-level operation. To help deal with this problem, NAD provides a switch in the rear of the Model 7140 receiver to reduce the operating voltage on its output transistors when driving loads of 4 ohms or less (this is designated the "normal" setting). When the switch is set to its "8-ohm" position, the increased power-supply voltage enables the amplifier to deliver its maximum output to nominally 8-ohm speakers." …..Interesting read regarding your receiver. When I first read your post, my suspicions were about the amplifier section of your receiver and how well or not it could handle the load of 2 pair of Allisons over a long period of time. Nothing lasts forever, and my first suspicions are that your amplifier section is getting "tired" sorry to say. In 43 years of dealing with the Allison Loudspeaker, I've never seen the kind of trouble you are experiencing be attributable to a ferrofluid or cap condition. Bill Quote Link to comment Share on other sites More sharing options...
intrique45 Posted January 9, 2020 Author Report Share Posted January 9, 2020 Maybe it was this? Wire touching the frame and shorting out? Quote Link to comment Share on other sites More sharing options...
newandold Posted January 10, 2020 Report Share Posted January 10, 2020 (edited) On 1/9/2020 at 6:30 PM, intrique45 said: Maybe it was this? Wire touching the frame and shorting out? Have to be very careful when removing and reinstalling the woofers. Those nonconducting tabs that secure the leads can easily end up like yours if they bang the cabinet. Bill Edited January 11, 2020 by newandold Clarify Quote Link to comment Share on other sites More sharing options...
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