Newer AR2Ax Tweeter out of phase?

[Guest sssand2]

All,

As I mentioned in my earlier thread, I am refurbishing some later model AR2Axs for a friend. I am working on 2 pair -- one in the serial # range of 282,xxx and the other in the range of 275,xxx.

Both sets have the 4 bolt woofer and the black supertweeter. When I was working on the first pair, I noted that the yellow (negative) wire was connected to the + terminal on the tweeter in both speakers. However, after checking the crossover diagram here and elsewhere, it appread to me that the black wire (positive) should be connected to the + terminal. I now have the second pair and just checked the wiring on them. Sure enough, the yellow wire was connected to the + terminal. Both pair were originally owned by the same person, but I doubt he opened them up. Have any of you AR experts seen this in newer 2Axs? I have tried them both ways, and the imaging seems better with the tweeter out of phase, though I haven't listened to them long in this configuration. I would like to hear your thoughts and experiences. Thanks!

Steve

[Carlspeak]

All the information I have shows the tweeter wired out of phase like the first pair of speakers you wrote about. This very common for APC type 2nd order filters where a flat response at the crossover point is desired.

Go with the former, not the latter.

[RoyC]

Steve,

Are these front-wired versions? If so, the negative yellow wire connects to the left surface tweeter terminal, as you face it. This terminal connects to the negative side of the tweeter through the fine lead wire crossed over beneath the electrical tape. This is the only wiring scheme I have seen for your version 2ax, the most recent having a 235,xxx serial number. The polarity would therefore not be reversed in the specimens I have seen.

The fine tweeter lead wires cross under the tape as they do in the AR-3a and AR-5. AR sometimes placed red "+" signs at the origin of the lead wire immediately next to the dome as well as at the termination of the wire(sometimes in both places!) depending on era, which makes it confusing. The + lead always originates on the left side of the dome as you face it.

To make matters more confusing the yellow wire is the positive tweeter and mid wire in the AR-3a and AR-5 :-)

Roy

[Guest sssand2]

>Steve,

>

>Are these front-wired versions? If so, the negative yellow

>wire connects to the left surface tweeter terminal, as you

>face it. This terminal connects to the negative side of the

>tweeter through the fine lead wire crossed over beneath the

>electrical tape. This is the only wiring scheme I have seen

>for your version 2ax, the most recent having a 235,xxx serial

>number. The polarity would therefore not be reversed in the

>specimens I have seen.

>

>The fine tweeter lead wires cross under the tape as they do in

>the AR-3a and AR-5. AR sometimes placed red "+"

>signs at the origin of the lead wire immediately next to the

>dome as well as at the termination of the wire(sometimes in

>both places!) depending on era, which makes it confusing. The

>+ lead always originates on the left side of the dome as you

>face it.

>

>To make matters more confusing the yellow wire is the positive

>tweeter and mid wire in the AR-3a and AR-5 :-)

>

>Roy

Roy,

These are not the front wired version, however the positive terminal as marked on the front of the tweeter is to the left as you are facing it.

Steve

[RoyC]

This appears to be another AR tweak.

Steve, do your 2ax woofers have the alnico, or later ceramic magnets?

Although visually identical to the original, the midrange driver's dcr was raised 3 ohms in later back-wired AR-2ax models equipped with ceramic magnet woofers. I bet the tweeter polarity was reversed at that time as well.

I agree with Carl's recommendation to leave the wiring as is.

Roy

[Guest sssand2]

Roy,

I suspect they are ceramic but how do I tell? The magnets are square with a round pole piece in the middle.

[onplane]

This whole issue of phase I find most interesting. Now, let me clarify. I have absolutely no idea on how the individual drivers are wired in my AR-3a’s (I am the original owner and have never modified that part of the xovers).

I am one of the very few people, however, that passively bi-amps my 3a’s. So I have control over the phase relationship of the signal sent to the mids/tweeters vs the phase of the signal sent to the woofer.

Below is a post I made a few months back on AK and thought you might find interesting:

In an earlier post, I reported that I accidentally discovered how phase impacts stereo separation and high frequencies. Turns out that post was premature.

Let me clarify, when I talk about “phase”, I’m refereeing to the phase relationship between the audio signal sent to the woofers and the audio signal sent to the mids/tweeters. I am NOT referring to the phase of the drivers in the left and right channel, because the drivers are in phase in my bi-amp arrangement … guaranteed! If they are out of phase, then I see that white “magic smoke”, but … that’s another story.

Whenever we horizontal bi-amp (one amp for woofers and another for mids/tweeters), we have the issue of phase difference between the respective audio signals, especially if we are NOT using identical amps.

Anyhow, my amps track in phase pretty good and I can see this on my dual trace scope. What I claimed as a discovery is that the TONE FLAT switch reverses the phase of the audio signal by 180 degrees. No question, in my amp the TONE FLAT switch does this.

Problem is I claimed that when the audio signals going to the woofer and the mid/tweeter are 180 degrees OUT OF PHASE, I saw a reduction in:

1. stereo separation

2. high frequencies

My observation was 100% correct for that particular piece of music. Unfortunately, what I learned is it’s NOT true for all music. Since I can alter phase with a flick of the TONE FLAT switch I can compare the resulting sound when the signals are “in” phase and “out” of phase by 180 degrees.

Here is what I’ve subsequently learned after listening to all kinds of music:

1. sometimes there is NO difference in resulting sound regardless of the phase

2. sometimes stereo separation and high frequencies are BETTER when the signals are OUT of phase

3. sometimes stereo separation and high frequencies are BETTER when the signals are IN phase

How can this be???

I mean, it doesn’t make any sense.

Companies have spent significant sums designing speaker systems to keep everything in phase, yet sometimes it sounds better when … the signals are out of phase??!!

Is it possible the sound engineers when “enhancing” the audio signals to make the cd masters, screw up the phase relationship between the bass and the high frequencies?

If this happens, then when I say it sounds better “out of phase” what’s really going on is that I have put the phase back in line.

This is NOT neat … it’s NOT tidy and it makes no sense.

Anybody have any ideas why the phase of high and low frequencies can result in such unpredictable outcomes?

Regards,

Jerry

PS: We have an interesting article in our library on this same subject:

http://www.classicspeakerpages.net/ar/documents/phase.zip

[RoyC]

Steve,

I'm guessing it looks like the woofer in the attached photo, which is a '76 2ax woofer with a ceramic magnet.

Roy

[Carlspeak]

....."Is it possible the sound engineers when “enhancing” the audio signals to make the cd masters, screw up the phase relationship between the bass and the high frequencies?

If this happens, then when I say it sounds better “out of phase” what’s really going on is that I have put the phase back in line.

This is NOT neat … it’s NOT tidy and it makes no sense.

Anybody have any ideas why the phase of high and low frequencies can result in such unpredictable outcomes?..."

I think your hypothesis in the first paragraph above may be right on target. I once had a friend who firmly believed that recordings are not all 'in phase'.

Good library reference also.

Attahced is a schematic from the library as well. You can follow the + and - from the connection points thru the circuit to the + and - at the speaker if that helps at all identify how the 3a's were wired.

Remember, it's all about the music

Carl

Carl's Custom Loudspeakers

[Guest sssand2]

Roy,

That's the one. Same part number too.

Steve