Help with AR-2Xa L-Pad and Crossover Wiring

[Norman Nicolai]

 

I am in the middle of replacing my speakersL-pad. The L-pad I am removing has a wire (looks like speaker wire) connecting the #1 and #B terminals. I don’t see it on the schematic I am using. (With my limited electronic reading skills, I should add...) I’m assuming that the previous owner had problems with the existing L-pad and wired them in the “full on” position, rendering them useless.

Is that a correct reading, and should I not replace that wire?

Thanks!

[Aadams]

Correct. No wire.   Are you installing new LPads or new pots?  Your photo image is an original pot.

[Norman Nicolai]

They’re called “Level Controls” by the same vendor that sells Roy’s Goo online. I assumed they were considered L-pads. Is there a difference and should I have gotten a different product?

Thanks for your help!                       

[Aadams]

Top is an 8 ohm lpad.  Do you have the 10 watt 25 ohm resistors to make them mimic the original pots?  

[Norman Nicolai]

I guess I need to go to the Parts Express website and order additional material...

Do you have a link to a schematic that shows where to wire the resistors in?

Again, thanks for your help!

[Aadams]

Look at page15 in the 3a restoration guide.  As long as they are in parallel they can be mounted anywhere from on the lpad to on the driver.  Most are placed on the lpad.  If you are not having your tweeters rebuilt or using the Hivi mod then don't put the resistor on the tweeter lpad.  The lpad alone will boost the output of your old and very tired tweeters if they are still working.   There is no way your tweeters are in good health even if they seem to work.

Adams

[lARrybody]

Not my picture, but I keep it around to clarify the wiring of a original pot and a l-pad.

[RoyC]

52 minutes ago, lARrybody said:

Not my picture, but I keep it around to clarify the wiring of a original pot and a l-pad.

Wow, that is an old photo of mine. Today I mount the resistor on the crossover board, and solder the crossover wiring to the L-pad terminals. Should the L-pad need to be replaced in the future, the resistor will not be disturbed.

The Parts Express L-pad is the same item as the one sold by the Ebay vendor mentioned above. 😉

Roy

[Norman Nicolai]

Thanks to everyone for your help!

I just ordered the resistors online and should have them by mid-week. If not for Aadams I would not have known about adding the resistor. IARrybody and RoyC’s photos helped too. (BTW, love your goo, RoyC...I assume that’s your stuff I use on my speaker surrounds. I have 4 sets of vintage KLH speakers and they wouldn’t sound as good as they do if not for your famous concoction!) 

I completed re-foaming the woofers a few days ago, so this project is tracking nicely.

I’ll post again after the L-pads are installed and everything is reassembled. I’ve also decided to do a more extensive refinishing on the cabinets even though they are in pretty decent shape, so it may be awhile before I’m back with the next report. I just can’t help myself when it comes to the cabinets. I started down this road initially working on speaker cabinets. Pulling speakers and working on the electronics inside the cabinets is a more recent venture, as evidenced by my lack of knowledge.

Again, I appreciate all the help. As this is my first AR speaker project, I’m psyched and looking forward to actually listening to them!

[JKent]

The L-pads from Vintage AR will come with instructions. Note that the tabs on the L-pads are not labeled the same as the original pots. It's also labeled on Roy's photo.

• L-pad 1 = 2,
• L-pad 2 = B,
• L-pad 3 =1.

[Norman Nicolai]

Got it, thanks. They did come with instructions from Vintage-AR. 
 

 

[Norman Nicolai]

I’ve discovered that both tweeters on the AR-2ax speakers I’m restoring are not working. I have been following another recent thread on this site so I ordered two HiVi Q1R tweeters along with two 0.05 mH inductor coils from PExpress as replacement tweeters. That purchase has led to a few more questions:

1. The replacement tweeters are wired to the back. Other than looking like original AR tweeters, is there any reason to have them front wired?

2. How is the inductor coil wired into the crossover or the new tweeter?

3. I thought I read on some other thread that you do not have to wire the 10W 25ohm resistor to the replacement tweeter L-pad if you replace the original tweeter with HiVi Q1R tweeter. Is that correct?

Thanks, and please feel free to chime in if you have any other advice about using the HiVi Q1R tweeter.

 

 

[JKent]

1. No--just for appearance
2. Fasten it to the back. Some people use a spacer. Not a bad idea but the tweeter is shielded so not essential.
3. Correct

[Norman Nicolai]

Thanks, JKent! The photo is very useful.

I am hoping the replacement tweeters will be delivered in less than a week.

Do you have an opinion about replacing the fiberglass batting inside the cabinets with newer, more modern fiberglass?

[JKent]

I'm told it's best to re-use the old stuff, although I have sometimes used new. Just don't use poly fill--it's not the same

[Norman Nicolai]

I’m a little confused about something. In the L-pad wiring photos from both RoyC and IARrybody there is only one green wire coming off B/2, in addition to the resistor wire. Because of the wire colors I am assuming it’s the mid L-pot. My old Mid L-pot has 2 green wires coming off it, one to the (-) neg terminal on the midrange speaker, and a second wire going to the T terminal on the back of the cabinet. Did I miss something?

Thanks.
 

[RoyC]

40 minutes ago, Norman Nicolai said:

I’m a little confused about something. In the L-pad wiring photos from both RoyC and IARrybody there is only one green wire coming off B/2, in addition to the resistor wire. Because of the wire colors I am assuming it’s the mid L-pot. My old Mid L-pot has 2 green wires coming off it, one to the (-) neg terminal on the midrange speaker, and a second wire going to the T terminal on the back of the cabinet. Did I miss something?

My photo was for demonstration purposes and shows the typical wiring for the 3a mid, not the 2ax.

Roy

[Norman Nicolai]

Thanks, Roy. 
That clears it up for me. The photos online seem to match my my wiring scheme, but as a novice I didn't want to start putting things together and soldering without a clarification.

[Norman Nicolai]

My AR 2ax’s are finally finished. Thanks for all the help I got here on this site. It would have been impossible for me to finish this undertaking without that help.

Which leads me to another set of questions. When I push down on the woofer cones to test how airtight the cabinets are, they spring back much more quickly than my Advent or KLH speakers. The woofer surrounds are brand new foam. I took great pains to install all the drivers with a “mortite” compound to get a good airtight seal. I then used more of that compound around the outside edges of each driver to make an even better seal. Whenever I have assembled KLH, Advent, or EPI speakers like that, I’ve gotten a good seal. Have I missed something with the AR’s?

When comparing the 2ax’s to my Advents during an A-B back and forth the AR bass was lacking, which makes me think the airtight seal could be the culprit.

However, I know that supposedly AR’s like power and sound better at higher volume levels so when I cranked them up the bass came up nicely. I lowered the tweeter and midrange L-pads and liked what I heard. The higher volume brought out the bass, and the lower highs and mids seemed more balanced. L-pads to the rescue!

Think I have discovered why L-pads are critical to AR speakers. Does that sound right?

[Aadams]

1 hour ago, Norman Nicolai said:

However, I know that supposedly AR’s like power and sound better at higher volume levels so when I cranked them up the bass came up nicely. I lowered the tweeter and midrange L-pads and liked what I heard. The higher volume brought out the bass, and the lower highs and mids seemed more balanced. L-pads to the rescue!

Think I have discovered why L-pads are critical to AR speakers. Does that sound right?

If you used new mortite on all the drivers, including the mids, your speakers are probably sufficiently sealed.  The difference in bass between the 2 systems is real though what you hear could also be influenced by different room positions. A fairer comparison would be to place the systems in the same spot and listen.  If both are operating properly, you will hear deeper bass notes from the Advent but the overall presentation of the 2ax will be smoother, cleaner and better balanced once you get the lpads adjusted to taste.  And yes, lowering the mid output can appear to increase the upper bass output.

I had OLA and 2ax at the same time and remember the OLA as exciting but the 2ax was easier to live with.  The OLAs would make great TV speakers. I regret selling them.

Happy Holidays

Aadams

[Norman Nicolai]

Thanks for the feedback, Adam’s.

The Advents and AR’s were positioned right next to each other, so it was a true A-B comparison, same music source and amplifier with a speaker selector switching back and forth between speakers. I’m not surprised that the AR’s are smoother and better balanced but am surprised that the Advents have more bass extension. I recently sold a pair of NLA’s and they had even more base than the OLA’s used in the comparison. 

The mortite like product is brand new and is sold by Parts Express. I’ve used it in all my speaker rebuild projects, and I used it with all the AR drivers, tweeters and mids included. The only thing I can think of is that the cabinets have an air leak somewhere, or I need to put the mortite over the screw holes for all the drivers.

Happy Holidays to you, too!

[Aadams]

On 12/24/2020 at 6:27 PM, Norman Nicolai said:

The only thing I can think of is that the cabinets have an air leak somewhere, or I need to put the mortite over the screw holes for all the drivers.

You have at least two leaks in the attenuator bore holes. If you have already done a good job of sealing, additional mortite won't extend the bass of the 2ax.

You can make the two systems sound the same at at about 4 meters by judiciously using a 10 band graphic equalizer, starting with both systems set to max on the attenuator controls.  But even after they sound indistinguishable at a distance, you can still hear the differences when you listen closer than say 3 meters. If you mostly listen for bass the Advent will sound better but over time, if you listen attentively, it seems many folks prefer the 2ax.

 

 

[Norman Nicolai]

I prefer the 2xa’s already. I just assumed that the 2xa’s would be superior to the Advents in every respect, including bass reproduction, since it’s a better speaker. I am amazed at how much control you can exert coloring the sound with the L-pads. My KLH and Advent speakers, with their 3 position switches, can’t compete. 

I’ve been driving the 2xa’s with my solid state HK3490 receiver. It produces 120 wpc, and I’ve bypassed its preamp in favor of the preamp in an Advent 300. I also have W5M mono blocks, and when I get my PAS2 preamp back from the shop I’ll find out if the speakers fare better with higher powered SS amps, or lower powered tube equipment. From what I have read, I’m betting on the higher powered SS amp, but we’ll see.