AR-2ax crossover schematic

[drspiff]

I was playing around with the free PCB Express software and decided to do something worthwhile at the same time. Here is a copy of the schematic for the crossover in the AR-2ax speakers.

http://audiokarma.org/forums/attachment.php?attachmentid=9455&stc=1
AR-2ax_schematic.jpg

BTW the PCB Express software is pretty cool and you can't beat the price.

 

[brainsmasher]

Thanks for that, I have been wanting to tear into one of my pairs of these and re-cap it so I can do an A/B with them. Now I gotta call PE and order the caps.

 

[ozmoid]

Thank You Spiff! I have just ordered surrounds for my AR-2ax woogers, and want to re-cap while I'm in there! Your sense of timing is impeccable!

 

[drspiff]

Parts Express did not have the 6uF cap in a Dayton, so I bought a 4uf and a 2uf and put them in parallel for 6uf. Then I put another 4 with the pair to give me the 4uf/6uf combination. After I carefully pried open the waxed paper wrapper off the existing 4uf/6uf block, I inserted the new caps into the old wrapper. Now the recap is invisible.

BTW the solid looking yellow-ish stuff in the old cap is wax. If you are having a hard time getting the box off, a little judicious heat from a heat gun will make things easier.

 

[ozmoid]

capacitor voltage

OK, I got into the cabs on my 2ax's, and the original caps are 50VDC. The other pair of 2ax's that MarkAnderson recapped for me are using the same MFD at 500V.

What is the significance of the voltage in the crossover? Does it have an impact? Speak in small words, I'm just getting started on the AK "post your way to a masters" Electrical Engineering Degree, and I really want to understand this.

 

[MarkAnderson]

Newer caps are typically rated for higher voltages. Everything I've seen/read suggests that this makes no difference (as long as the new caps are rated higher, of course). - Mark

 

[jerryjg]

OK, I got into the cabs on my 2ax's, and the original caps are 50VDC. The other pair of 2ax's that MarkAnderson recapped for me are using the same MFD at 500V.

What is the significance of the voltage in the crossover? Does it have an impact? Speak in small words, I'm just getting started on the AK "post your way to a masters" Electrical Engineering Degree, and I really want to understand this.

I would like to have my AR2XA's recapped. I have sent a private message to Mark Anderson, however I do not know if he Would be able to do this for me at this time. Can anyone reccomend someone else who does this ?I would like to get both X-overs recapped, and also new trim Pots. Thank you.

 

[ShaneC]

I was playing around with the free PCB Express software and decided to do something worthwhile at the same time. Here is a copy of the schematic for the crossover in the AR-2ax speakers.

http://audiokarma.org/forums/attachment.php?attachmentid=9455&stc=1
AR-2ax_schematic.jpg

BTW the PCB Express software is pretty cool and you can't beat the price.

I'm a little late to the party, but needed this (again) and wanted to say "Thanks", but uh...what's a Wooger?

 

[Zilch]

Nearly 1000 views of this thread, and the schematic seems to be wrong.

1) Not L-Pads, rather, potentiometers, in this case 25W wirewounds, apparently.

2) 4uF (cap Blk) goes to the tweeter pot, not the mid, and 6 uF (cap Grn) to the mid pot, best I have been able to determine.

How have members recapping AR2Ax been knowing which cap to put where?

http://www.classicspeakerpages.net/IP.Board/index.php?s=&showtopic=4467&view=findpost&p=74232

Somebody knows better, konk me with a corroded AR pot wrapped in a wad of rockwool....

 

[ShaneC]

I'd say that's a Pot. And here I've been searching for a decent price on 15ohm L-pads. *sigh*.

Yes, the Black is for the Tweeter; I'm pretty sure the Yellow was Common and Green for the mid - but I don't have mine open to verify right now.

And it's only taken us 2.5 years to figure this out!

 

[ShaneC]

Here's what they've got over at Classic Speaker Pages:

 

[Zilch]

Here's what they've got over at Classic Speaker Pages:

Yes, but it doesn't tell us which is which on the cap.

I showed everybody how to replace the pots with a simple resistor stack and three-way toggle switch in another thread here. The cost is less than a pot or L-pad. To the best of my knowledge, I'm the only one that's ever actually done it to date.

There's a stepped attenuator promoted over on Classic Speaker Pages. You can do it yourself through a limited range for peanuts. Go figure.

http://www.classicspeakerpages.net/_Media/sa-16-arassyman.pdf

If I may be permitted a brief moment of attitude here, I think the whole AR pot/recap thing is a stupendous wank wherever folks have attempted to tackle it. There's page after page of useless blather and misinformation everywhere.... :banghead:

 

[ShaneC]

Yes, but it doesn't tell us which is which on the cap.

I showed everybody how to replace the pots with a simple resistor stack and three-way toggle switch in another thread here. The cost is less than a pot or L-pad. To the best of my knowledge, I'm the only one that's done it.

There's a stepped attenuator promoted over on classic speaker pages for big bucks. You can do it yourself through a limited range for peanuts. Go figure.

I'd like to get them "close" to original, provided I can get the parts cheap (only paid $10 for the pair). I'll take a look at your resistor stack setup.

 

[Zilch]

http://audiokarma.org/forums/showthread.php?p=1369693&#post1369693

 

[onplane]

Shane, if you really want to vary the output of the mid and tweeter, Roy has devised a simple solution using 8 ohm L-pads.

If you add a 25 ohm 10 watt resistor across both the mid and tweeter, then your 15 watt 8 ohm L-pads will mimic those old pots (in the range of interest).

This solution is darn close to those old pots and has similar power handling capabilities.

There is another issue you need to understand and that is those old dome 3/4" tweeters have reduced output and are near end of life. While the L-pad + 25 ohm resistor will mimic the old pots, it will not mimic the sound those speakers once produced.

For the tweeter, I'd recommend that you use the L-pad by itself and set to the maximum output. Alternatively, you could simply by-pass the pot completely.

For the mid driver, the L-pad with 25 ohm shunt will give you plenty of control. That's not what I would do, however. I'd solder the wiper lead to the top of the pot. This nails the mid driver to it's maximum output, which is AR's recommended setting for a flat freqency response.


Hope this helps ....

Regards,
Jerry

 

[Zilch]

For the tweeter, I'd recommend that you use the L-pad by itself and set to the maximum output. Alternatively, you could simply by-pass the pot completely.

They're the same thing, and neither replicates the original circuit. With an L-pad set to max, the series resistance is 0 and the parallel resistance goes to infinity.

That's how I got into this in the first place, "Why doesn't everybody just stick an L-pad in there...?"

 

[onplane]

They're the same thing, and neither replicates the original circuit. With an L-pad set to max, the series resistance is 0 and the parallel resistance goes to infinity.

That's how I got into this in the first place, "Why doesn't everybody just stick an L-pad in there...?"

Yep, Zilch, electrically they are the same ... except with an L-pad you have the ability to match the speakers. Supposing the foam suspension in the dome tweeters didn't age the same. For example, the left speaker's tweeter is still producing decent high frequencies.


L-pads allow you to cut back on the speaker with the "least aged" tweeter to match with the weaker speaker.

Now, we can argue whether we should or not. I would and then I'd use an EQ or tone controls to boost the highs.

Regards,
Jerry

 

[spkrdtr]

PM me for info on my AR upgrade services.
carlspeak@aol.com

 

[Zilch]

I do "Upgrades," too....

 

[Bluelick]

This is a pretty old thread, but a word of warning to anyone that ends up here--the schematic in the original post has the 4 and 6uF capacitors reversed. I used this schematic without cross-checking that and had to go back into the speakers to reverse the problem. The mistake was obvious when I went back and looked at my pictures of the crossover, because the capacitance is clearly color coded on the old wax capacitor block.