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nice find lets see some pictures
Unless I hear signs of cap failure, no. I have the original caps in my 2 sets of Dynaco A25xl and my Advent Model 3s. I just don't really worry about stuff like that. If it ain't broke, don't fix it.In the case of vintage Marantz stuff, if you want the value of it to go to almost zero, then replace all the original caps.Mike Zuccaro of Audiocraftsman: (http://audiocraftsman.com/) gets really pissed off when people do that. He's told me several times that for the most part, it's a waste of time. Mike has done work for me with my vintage Marantz stuff. His qualifications are staggering.Wayner
I have received the AR-4Xs on Saturday. While they are, in appearance, mint, there are some issues. These issues have plunged me into a rebuild. Problem number one was (as expected) a troublesome L-pad. Problem 2 was discovered when I had the box open and tested the capacitor. Way out of rating.I hope to post some photos tomorrow, but I'm getting a crown. No, not of a kingdom, rather on a troublesome tooth.I have repaired the L pads. I must say they are robustly built, being made with a ceramic coil section. The pads are held together by a wire bale, and after removing this, the entire innards can be gotten at. The usual culprit was the contact swipe, being very corroded. Some Deoxit-5 and some steel wool have made them shinny again.Tomorrow, I will order 2 20mfd capacitors to replace the old ones. This speaker is rolled off at 1000 cycles. The cross-over is a simple 6db slope, with a 20mfd cap in series with the tweeter (L-pad is in between cap and tweeter as well, and a 1.2mh coil in parallel with the woofer terminals.Wayner
They are L-pads. L-pads are used to reduce tweeter volume, without screwing up the values of the cross-over network. It is a 15 ohm, 25 watt version. L-pads are designed for low impedance networks.w
I have the original wiring diagram. They are 15 ohm and they are repaired. I've restored probably 15-20 pairs of speakers in my life and I've just about seen it all, tho every make has another surprise.If you will read my earlier post, I edited it. Of course the inductor is in series, as my brain sometimes is.I have done lots of research on this, including other audio sites. There is plenty-o-dis-information out there.For one, they say the cross-over is at 1200hz, but it's really even lower then that, at 1000 hz. Why AR chose a odd ball 15 ohm L-pad is beyond me, and I respect you questioning my info. I question my own info, at least until I get inside the speakers and get a good read on the cross-over.This is the first AR I have had apart, but simple as it is, there is no way to return it to it's original condition. The capacitor is made by Industrial Cond.(uctor?) Corp out of Chicago and is a real odd duck in construction. The schematic does match the actual.Wayner
There are 3 terminals on the L-pad, it's under the wire bale. Yellow wire goes to it.I have to change the caps, because they measure at 30mfd on one an 35.X on another. That would put the X-over down around 500hz........no good.After talking to my fearless leader (Frank Van Alstine), he is going to send me some 10mfd, 100 volt capacitors, and I will put 2 in parallel to get the 20mfd value as the original.I find it interesting (and I did not know this) that some types of caps will increase in value as they age (as apparently these did), and the result was a lower X-over point. I was suspect of this after some listening when I first got them. That and the L-pad conditions, are the steering mechanism to overhaul these.AE, yes, I want to at least restore them to as new performance condition. I do not want to change any drivers or deviate from the original design. Basically, I want to make them like new again.Wayner
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