correct wiring for bypass, help... ar3's

[Guest phillydog]

thanks for all the info so far, on dialing in my 3's.

did take the advice on bypassing the tweets and maintaining the mid pots, but heres my dilema, unfortanately both of the mid pots were shot, even ater extensive cleaning, so i decided to move the tweeter pot over and bypass the high and maintain the mid unit, didnt work! the tweeter is functioning but the mid is not. i know the mid worked before i messed with it only in one spot though one the l control. so what happened, did i not wire correctly? did have to resolder one mid wire on the terminal externally, not very easy, is that wire platnium or something? accidentialy hit it with the woofer. anyway befor i go back in what is the correct wiring for the bypass, will put in replacement in future, but for now wanta hear some tunes with all three units functioning... thanks

[Guest dogmeninreno]

Here is a link to a xover schematic on this site. It may help you out? Dale

http://www.arsenal.net/speakers/ar/classic/ar-3a/AR3axo.jpg

[Guest dogmeninreno]

Well, I posted the link but it seems to have given you the schematic. Oh well, Dale

[Guest dogmeninreno]

>thanks for all the info so far, on dialing in my 3's.

>did take the advice on bypassing the tweets and maintaining

>the mid pots, but heres my dilema, unfortanately both of the

>mid pots were shot, even ater extensive cleaning, so i decided

>to move the tweeter pot over and bypass the high and maintain

>the mid unit, didnt work! the tweeter is functioning but the

>mid is not. i know the mid worked before i messed with it only

>in one spot though one the l control. so what happened, did i

>not wire correctly? did have to resolder one mid wire on the

>terminal externally, not very easy, is that wire platnium or

>something? accidentialy hit it with the woofer. anyway befor i

>go back in what is the correct wiring for the bypass, will put

>in replacement in future, but for now wanta hear some tunes

>with all three units functioning... thanks

Let me start over. I sent you a xover for the AR3a and you have AR3's so lets use this link. http://www.arsenal.net/speakers/ar/classic/ar-3/ar3xorig.jpg

[johnieo]

>Well, I posted the link but it seems to have given you the

>schematic. Oh well, Dale

Recently I purchased two AR-3a systems -- one of which was advertised as an AR-3 "factory modified to AR-3a." Tonight I carefully removed the woofers to examine the inside and to determine why the retrofit was lighter than the original (45 versus 53 lbs).

First- I observed that these units were not wired exactly as shown the Layne Audio schematic Dale posted immediately above. The difference being a 0.51 ohm resistor in series with the 50 uF capacitor. The Layne schematic shows two terminals to the left of the mid-range inductors, which are connected with a "wire." The original AR-3a has a fine wire whose resistance measures ~0.5 ohm. The retrofit unit contains a 0.51 ohm, 10 W resistor between these terminals.

QUERY 1 : Dale, have you or anyone else observed this distinction; has it been shown to affect the crossover rolloff; does it serve to limit transient currents in the 50 uF? Did Layne miss the boat when copying this circuit?

Second: More than one factor accounts for the 8 lb. difference between the two units. The original unit contains the older, heavy aluminum-foil 150/50 uF package. This is a significant fraction. The Fiberglas fillers were essentially equal (1 lb, 13 oz versus 1 lb, 11 oz). The cases materials were different (chipboard and MDF) and this likely accounts for the remainder. This raises the question of aging of the retrofit cap.

Query 2: The 1976 retrofit contains a 150 uF "Royalitic" (Industrial Capacitor Corp) marked with an AR part number in place of the aluminum-foil-wound cap used in the original unit. Do those of you who repair/rebuild speakers automatically replace 28-yr-old capacitors of this style?

And last, a comment: After removing the Fiberglas in the retrofit unit, I noticed that the 6-uF-capacitor was hanging in "free space" with 1.5-in-long *uninsulated* leads! Further examination showed that the cap lead connected to pin #3 on the tweeter pot was pushed over against pin #1 on the mid-range pot during insulation stuffing. Thus, the capacitor was connected across the speaker input terminals with no signal going to the tweeter (forever or at least intermittently)! Makes one wonder who the tech was watching at that moment... Conclusion, don't assume anything.

The comment elsewhere about wearing dust mask and rubber gloves when handling Fiberglass is well stated. Should some get on the skin, wash hands in very cold water -- this aids in closing the skin's pores.