Jump to content

2Ax’s mid-range driver


DOB

Recommended Posts

Hello:

I own a pair of 2Ax’s and was wondering about the quality of the mid-range driver. I have gone through two of these derivers recently and each have exhibited similar forms of distortion - what sounds like cone break-up. It is not easily noticed and only occurs under certain conditions. Would any one like to comment on the 2Ax’s mid-range design and their experiences with these drivers?

The conditions for the “break-up” distortion occur at higher frequency and usually under complex musical passages – e.g. certain massed string symphonic passages. The crossover caps have been replaced as have the control potentiometers- with L-pads, as per the AR 3 restoration manual. I have used different amps and reversed the sides for each speaker. It is, as far as I can tell, the mid-range drivers. I have been careful not to over drive the speaker and used a 55-watt amp and an 80 watt one as well. But with the L-pad all the way up and the preamp volume set at 11:00 there is distortion in the two drivers that I have used in the same speaker. My other speaker is fine.

Thank you.

Link to comment
Share on other sites

Hello:

I own a pair of 2Ax’s and was wondering about the quality of the mid-range driver. I have gone through two of these derivers recently and each have exhibited similar forms of distortion - what sounds like cone break-up. It is not easily noticed and only occurs under certain conditions. Would any one like to comment on the 2Ax’s mid-range design and their experiences with these drivers?

The conditions for the “break-up” distortion occur at higher frequency and usually under complex musical passages – e.g. certain massed string symphonic passages. The crossover caps have been replaced as have the control potentiometers- with L-pads, as per the AR 3 restoration manual. I have used different amps and reversed the sides for each speaker. It is, as far as I can tell, the mid-range drivers. I have been careful not to over drive the speaker and used a 55-watt amp and an 80 watt one as well. But with the L-pad all the way up and the preamp volume set at 11:00 there is distortion in the two drivers that I have used in the same speaker. My other speaker is fine.

Thank you.

I rescued and restored a pair of AR2axs just as they were headed for the curb. One of them had the same problem. I also rescued a pair of AR2as which have the old jensen 5" drivers I didn't like and the cones are badly warped. At first I thought it was the tweeter in the AR2ax was bad but it turned out to be the midrange. I bought three on e-bay. I've only fully restored the AR2axs so far and the replacement driver turned out to work just fine, surprisingly well in fact.

The tweeters seem to function perfectly. I found that I needed to set the tweeters to their max output and the midranges to slightly less than half output to get the most accurate sounding results. I then equalized it by ear and the results come very close to what you would expect from combining the FRs of the drivers shown in the library, a boost in the deep bass and in the treble. There's also a slight cut required in the midrange. When the FR is flattened this way, I've been amazed at how well the speaker perform, much better than I'd ever heard them in the past when they were current. Very accurate, very clear, excellent high frequency dispersion with no perceived changed to spectral balance at 45 degrees off axis, the maximum I can go with the speakers in the corners of a room toed in 45 degrees. Bass is excellent too but I did damage one AR2a 10" driver so it's not nearly as robust as the 12" version. BTW, the edge to edge diameter across the inside of the outer suspension is 7" which is exactly the same as for KLH model 6. I haven't applied any sealant to the KLH 6 cloth suspensions and at the moment the AR2ax strikes me as having better bass between the two.

I'll probably replace the Jensen drivers in the AR2as with the AR2ax midranges but I don't know what I will do about tweeters. The output from the 8 ohm version of the AR3 driver seems very weak. That's always the hard part in restoring these, the tweeters. I've got all kinds including some Tonegen ribbons. Try to find some of these AR2ax midranges on ebay, there seemed to be plenty of them when I was looking around a year ago. Othewise you can try a 3 1/2 " midrange driver from Parts Express, they aren't expensive but it won't be an exact match.

Link to comment
Share on other sites

Howdy:

Addendum to my last post:

Please see the attached schematic for the AR 2ax and note the 2-ohm resistor in series with the mid- range driver. Also please see pages 10 and pages 14, and 15th of the AR 3a “Restoring the AR-3a” manual. The crossovers for the two speakers are of course different.

The 2ax’s speakers that I bought had the AR 3a L-pad, parallel 25 ohm mid and high driver resistors installed but is missing the 2-ohm series resistor on the mid.

Should I remove the 25-ohm resistors and/or reinstall the 2-ohm resistor back in series with the mid- range driver, leaving the 8-ohm L-Pad?

Any thoughts?

Thank much.

Dan

2ax_connection_diagram.pdf

Link to comment
Share on other sites

I rescued and restored a pair of AR2axs just as they were headed for the curb. One of them had the same problem. I also rescued a pair of AR2as which have the old jensen 5" drivers I didn't like and the cones are badly warped. At first I thought it was the tweeter in the AR2ax was bad but it turned out to be the midrange. I bought three on e-bay. I've only fully restored the AR2axs so far and the replacement driver turned out to work just fine, surprisingly well in fact.

The tweeters seem to function perfectly. I found that I needed to set the tweeters to their max output and the midranges to slightly less than half output to get the most accurate sounding results. I then equalized it by ear and the results come very close to what you would expect from combining the FRs of the drivers shown in the library, a boost in the deep bass and in the treble. There's also a slight cut required in the midrange. When the FR is flattened this way, I've been amazed at how well the speaker perform, much better than I'd ever heard them in the past when they were current. Very accurate, very clear, excellent high frequency dispersion with no perceived changed to spectral balance at 45 degrees off axis, the maximum I can go with the speakers in the corners of a room toed in 45 degrees. Bass is excellent too but I did damage one AR2a 10" driver so it's not nearly as robust as the 12" version. BTW, the edge to edge diameter across the inside of the outer suspension is 7" which is exactly the same as for KLH model 6. I haven't applied any sealant to the KLH 6 cloth suspensions and at the moment the AR2ax strikes me as having better bass between the two.

I'll probably replace the Jensen drivers in the AR2as with the AR2ax midranges but I don't know what I will do about tweeters. The output from the 8 ohm version of the AR3 driver seems very weak. That's always the hard part in restoring these, the tweeters. I've got all kinds including some Tonegen ribbons. Try to find some of these AR2ax midranges on ebay, there seemed to be plenty of them when I was looking around a year ago. Othewise you can try a 3 1/2 " midrange driver from Parts Express, they aren't expensive but it won't be an exact match.

Thank you for the information.

I have gone through three drivers now. Looking into my situation a little deeper I found my AR 2ax's are missing the 2-ohm resistor in series with the mid- range driver. Also – they may have the wrong AR 3ax’s 25-ohm parallel resistors applied – as per the restoring manual.

Cheers - Dan

Link to comment
Share on other sites

Howdy:

Addendum to my last post:

Please see the attached schematic for the AR 2ax and note the 2-ohm resistor in series with the mid- range driver. Also please see pages 10 and pages 14, and 15th of the AR 3a “Restoring the AR-3a” manual. The crossovers for the two speakers are of course different.

The 2ax’s speakers that I bought had the AR 3a L-pad, parallel 25 ohm mid and high driver resistors installed but is missing the 2-ohm series resistor on the mid.

Should I remove the 25-ohm resistors and/or reinstall the 2-ohm resistor back in series with the mid- range driver, leaving the 8-ohm L-Pad?

Any thoughts?

Thank much.

Dan

Dan,

If your speakers are using l-pads (with or without 25 ohm resistors in parallel with mids and tweeters), be aware that when the l-pad is set to maximum, all (level control) resistance is removed from the circuit. This is different than when an original pot is set to max. The original pot set to maximum or fully "increased" retains 15 to 16 ohms in parallel with the driver, resulting in less driver output than a maxed l-pad provides. The bottom line is that the 2ax mid and tweeter can easily be pushed beyond their limits with l-pads set to maximum at high volume. They were never meant to be driven that hard.

That 2 ohm resistor in the schematic you are referring to is not part of the original design...and will not address your problem. You would be better off turning your mid level control down a bit. In my experience most folks don't have the 2ax mid level controls (especially when they are l-pads) set to maximum.

Roy

Link to comment
Share on other sites

Dan,

If your speakers are using l-pads (with or without 25 ohm resistors in parallel with mids and tweeters), be aware that when the l-pad is set to maximum, all (level control) resistance is removed from the circuit. This is different than when an original pot is set to max. The original pot set to maximum or fully "increased" retains 15 to 16 ohms in parallel with the driver, resulting in less driver output than a maxed l-pad provides. The bottom line is that the 2ax mid and tweeter can easily be pushed beyond their limits with l-pads set to maximum at high volume. They were never meant to be driven that hard.

That 2 ohm resistor in the schematic you are referring to is not part of the original design...and will not address your problem. You would be better off turning your mid level control down a bit. In my experience most folks don't have the 2ax mid level controls (especially when they are l-pads) set to maximum.

Roy

Thank you Roy. In order to address the distortion I just adjusted one mid-driver l-pads to the 8 o’clock position – way down. The other speaker, in the other cabinet, does not exhibit the same problem in any of the L-Pad positions.

There may be something else a little funky about my speaker. I have used three mid drivers in the same unit and each exhibit the same issue in the same cabinet. L-pad problems?

Dan

Link to comment
Share on other sites

Thank you Roy. In order to address the distortion I just adjusted one mid-driver l-pads to the 8 o’clock position – way down. The other speaker, in the other cabinet, does not exhibit the same problem in any of the L-Pad positions.

There may be something else a little funky about my speaker. I have used three mid drivers in the same unit and each exhibit the same issue in the same cabinet. L-pad problems?

Dan

I have never heard of an l-pad causing a problem like that unless it is improperly wired. If it is not the wiring, it most likely has something to do with 40 year old drivers.

Just to be sure it is not something other than a speaker issue, switch the left and right leads to see if the problem follows the speaker or the amp channel.

Roy

Link to comment
Share on other sites

Thank you Roy. In order to address the distortion I just adjusted one mid-driver l-pads to the 8 o’clock position – way down. The other speaker, in the other cabinet, does not exhibit the same problem in any of the L-Pad positions.

There may be something else a little funky about my speaker. I have used three mid drivers in the same unit and each exhibit the same issue in the same cabinet. L-pad problems?

Dan

The AR2Ax midrange driver is protected by the 6 mfd series wired capacitor which acts as a 6db per octave high pass filter. It has no high frequency cutoff device. The potentiometer further reduces current relative to the output of the woofer. The midrange pot is used as a voltage divider. The speaker will play moderately loudly without damage but it was not engineered to play rock music at deafening levels. Since I had the identical experience I assume that some of these drivers have either been abused due to relatively modest power handling capability or may have deteriorated. The good news is that there were a lot of them made, they are cheap and they are readily available used on e-bay. They should cost no more than about $10 to $15 each. I replaced the caps with Parts Express non polarized that cost a few cents each and they work just fine. I looked at the driver and there seemed nothing particularly special about it. If you buy a substitute, buy them in pairs so both speakers will match. Be sure to get one that is 8 ohms and designated as a midrange with a sealed back to prevent the woofer's pressure wave from reaching the cone.

Link to comment
Share on other sites

The AR2Ax midrange driver is protected by the 6 mfd series wired capacitor which acts as a 6db per octave high pass filter. It has no high frequency cutoff device. The potentiometer further reduces current relative to the output of the woofer. The midrange pot is used as a voltage divider. The speaker will play moderately loudly without damage but it was not engineered to play rock music at deafening levels. Since I had the identical experience I assume that some of these drivers have either been abused due to relatively modest power handling capability or may have deteriorated. The good news is that there were a lot of them made, they are cheap and they are readily available used on e-bay. They should cost no more than about $10 to $15 each. I replaced the caps with Parts Express non polarized that cost a few cents each and they work just fine. I looked at the driver and there seemed nothing particularly special about it. If you buy a substitute, buy them in pairs so both speakers will match. Be sure to get one that is 8 ohms and designated as a midrange with a sealed back to prevent the woofer's pressure wave from reaching the cone.

Thank you. It was indeed the driver(s). I went through six of them with a local loudspeaker technician to get one good pair. Most came from eBay and each seller indicated that they were in “good” working condition. The word “good” is clearly subjective.

If there is a suitable drop in replacement it would be good to hear of it. The measurements taken on my good drivers indicated a relatively flat response across the range used without a “shelf”. Perhaps this is part of the AR 2ax allure?

Dan

Link to comment
Share on other sites

Thank you. It was indeed the driver(s). I went through six of them with a local loudspeaker technician to get one good pair. Most came from eBay and each seller indicated that they were in “good” working condition. The word “good” is clearly subjective.

If there is a suitable drop in replacement it would be good to hear of it. The measurements taken on my good drivers indicated a relatively flat response across the range used without a “shelf”. Perhaps this is part of the AR 2ax allure?

Dan

Glad you found a satisfactory replacement. Take good care of it, and try to refrain from maxing the l-pads at higher listening levels. :rolleyes:

There are no drop-in replacements.

Roy

Link to comment
Share on other sites

  • 2 years later...

Decided to revive this thread as I would appreciate advice on which way to proceed with my AR2ax restoration.

One of the cabinets has the midrange metal cover & F/glass missing so my dilemma is:

Do I remove the other cover to match the two speakers acoustically?

Can I fashion some sort of cover to replicate the result? ( not generally avail.w/out midrange driver)

From my research it seems to protect the driver from excessive movement & damage when played at high volume.

Any guidance would be welcomed.

Clive.

Link to comment
Share on other sites

Decided to revive this thread as I would appreciate advice on which way to proceed with my AR2ax restoration.

One of the cabinets has the midrange metal cover & F/glass missing so my dilemma is:

Do I remove the other cover to match the two speakers acoustically?

Can I fashion some sort of cover to replicate the result? ( not generally avail.w/out midrange driver)

From my research it seems to protect the driver from excessive movement & damage when played at high volume.

Any guidance would be welcomed.

Clive.

If you want an original 2ax you need a mid with the fiberglass pad and grille. They are fairly common, and often show up on Ebay at reasonable prices.

You can also post a request in the For Sale/Wanted section of the forum. If you are able to acquire a dead one, you could transfer the grille and fiberglass pad to your naked one.

If you are not in the US, the above suggestions may not be as useful in terms of availability and cost.

Roy

Link to comment
Share on other sites

Unforunately I'm from Australia so would be over $100 inc. delivery.

Will have to consider the benefit - does it make much of a difference sonically,

leaving aside the aesthetics?

Clive.

I have never tried it with 2ax mids, but the AR dome mids do not sound bad with the grilles and pads removed.

There will be at least a slight sonic difference...but the sound will probably be acceptable.

Roy

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...