AR-3a Crossover Resistors

[James Bond]

"In restoring the AR-3a manual" it recommends when replacing the capacitors and using PP types, section 3.9 of the manual recommends adding non-inductive resistors in series with those capacitors. I can find Mills 12 watt non-inductive for the high range capacitors, but I don't know where to find 20 watt non-inductive for the low range capacitors. Mouser has 25 watt standard wire wounds but they are not non-inductive. Any recommendations where I can find these?

Also, does anyone know where to get the plastic cable tie brackets illustrated in figure 3.18?

Help appreciated.

[JKent]

does anyone know where to get the plastic cable tie brackets illustrated in figure 3.18?

Those are a standard hardware item. You can find them in an electric supply house, a good hardware store, or even Lowes/HD. They also sell them in electronics parts stores and at PartsExpress. It's a good idea to use a small flat-head screw to secure it. Although it has two-sided tape I like the extra security. I think a #6 1/2" Philips flat-head should do it.

Kent

PS Trying to get some info on those resistors. They are not "required"--they are just there to make the film caps sound more like electrolytics. Will let you know if I find a source.

[RoyC]

"In restoring the AR-3a manual" it recommends when replacing the capacitors and using PP types, section 3.9 of the manual recommends adding non-inductive resistors in series with those capacitors. I can find Mills 12 watt non-inductive for the high range capacitors, but I don't know where to find 20 watt non-inductive for the low range capacitors. Mouser has 25 watt standard wire wounds but they are not non-inductive. Any recommendations where I can find these?

Also, does anyone know where to get the plastic cable tie brackets illustrated in figure 3.18?

Help appreciated.

We debated the inclusion of the small series resistors as an attempt to address and emulate the presumed higher esr of the original capacitors. I doubt any of us feel it is absolutely necessary. At least I don't, and do not use them in my restorations.

If you do decide to include them, the non-inductive type is not a requirement. The .27 ohm resistor referred to in the document is a conventional 20 watt sandcast type sold by Parts Express:

http://www.parts-express.com/pe/showdetl.c...tnumber=017-.27

The difference in sound by adding the resistors is not going to be noticed by most (if not all) ears, and the difference in inductance even less so.

Roy

[Diamonds&Rust]

"In restoring the AR-3a manual" it recommends when replacing the capacitors and using PP types, section 3.9 of the manual recommends adding non-inductive resistors in series with those capacitors. I can find Mills 12 watt non-inductive for the high range capacitors, but I don't know where to find 20 watt non-inductive for the low range capacitors. Mouser has 25 watt standard wire wounds but they are not non-inductive. Any recommendations where I can find these?

Also, does anyone know where to get the plastic cable tie brackets illustrated in figure 3.18?

Help appreciated.

We've talked and argued this just about to-death over the years.

Here's what I've "decided." "Deciding" a thing isn't necessarily the same thing as "knowing" a thing.

What possible difference could it make to put a resistor on a capacitor that's attached to a potentiometer? Heck, just move the potentiometer, and voilla!, more resistance!

So why is there even any debate?

I *know* this is insane. "Knowing" a thing is the same thing as "knowing" a thing.

The difference in resistor on / resistor off CAN be heard. Why? I'm not getting involved, but the only sane guess is an effect in the crossover region where two drivers are playing the same frequency. Don't ask what effect because, as I say, I'm not getting involved. Tempers flair. Accusations fly. Faiths are shattered.

Why do I recommend you simply forget the resistor? It's easier to leave it out AND most importantly we are talking about a difference you really have to listen-for like you're trying to hear the position of a tiger crouching in the dark just out of your eyesight. You may be able to tell the tiger's there by hearing its breath frighten a cricket into hopping to a different leaf of grass, but man... you gotta really be listening like your life depends on it. And it doesn't. The tiger's gonna eat you whether you know where it is, or not.

Okay, so maybe it's a little more obvious than cricket-hopping, but the truth is that you cannot possibly know that unless you take the time to do one speaker with, and one speaker without, the resistor, then carefully set-up an A/B listening-test, then set the knobs so that they are both as sonically much alike as possible (meaning you have to increase the pots on the one with the resistors), and then do your A/B test with music you know like the back of your hand.

Whether you can hear it lurking or not, there is no sonic tiger that's gonna jump-out of the dark and eat your face.

I'm not saying that resistance is useless, I'm just sayin' that there is no way you could walk into a room with a pair of 3as playing and be able to discern if there were resistors on the caps or not. You'd have a 50/50 chance of guessing, but you would never know for sure unless you pulled the woofer out and looked.