AR3 Pot question, if you please

[joelongwood]

First off, let me thank everyone on this board for being so knowledgeable and generous with that knowledge. Having purchased a pair of AR4x back in '68, I've been kind of an AR aficionado ever since. I currently have, besides those original 4x, another couple of pairs of 4x's, a pair of 4's, two pair of AR2a's, two pairs of 2ax (both pre and post 1970), two pair of 5's, a pair of 3a's, and a single AR2 (a mate is coming shortly). Some of these speakers have fully functional pots, others are intrermittent, while others I've had to jumper across the pots until I can get around to cleaning or replacing them.

Now to my question......the pair of AR3's that I acquired a few weeks ago had completely non-functioning pots, so I soldered a jumper across both the tweeter and mid pots. I've searched everywhere on this site and on Audiokarma to find out whether jumping the pots is the same as cutting the wire and soldering directly to the top of the pot......in essence bypassing the pot. I ask this because, even with the mid pot jumpered, the midrange output on the AR3's is very low, at least in comparison to any of the other 3 way AR speakers I have. I have to put my ear directly up to it to hear anything, and there doesn't seem to be much direct sound at all through the small circular cap of fiberglass that is under the wire mesh. If I move my head slightly to the sides of the dome, I can hear the mid clearly, but I have to be very close The tweeter seems to have much greater output.....is this normal? Would I get more output from the midrange if I bypassed the pot?

Thanks for any info or suggestions you may be able to furnish.

Bob

[onplane]

>Now to my question......the pair of AR3's that I acquired a

>few weeks ago had completely non-functioning pots, so I

>soldered a jumper across both the tweeter and mid pots. I've

>searched everywhere on this site and on Audiokarma to find out

>whether jumping the pots is the same as cutting the wire and

>soldering directly to the top of the pot......in essence

>bypassing the pot. I ask this because, even with the mid pot

>jumpered, the midrange output on the AR3's is very low, at

>least in comparison to any of the other 3 way AR speakers I

>have. I have to put my ear directly up to it to hear anything,

>and there doesn't seem to be much direct sound at all through

>the small circular cap of fiberglass that is under the wire

>mesh. If I move my head slightly to the sides of the dome, I

>can hear the mid clearly, but I have to be very close The

>tweeter seems to have much greater output.....is this normal?

>Would I get more output from the midrange if I bypassed the

>pot?

>Thanks for any info or suggestions you may be able to furnish.

>

>Bob

Bob, "jumping" the pots could lead to disaster and is a very, very bad idea.

That is, if you just jumped the wiper lead to the "top of the pot" the wiper is still in the circuit. If someone (a child for instance) turns the pot to max decrease, that wiper will short the pot, AND the speaker, leaving your amp driving just a cap!!

In addition, with the wiper still in the circuit, it WILL depending upon position, reduce energy sent to the drivers. By-passing prevents the pot from dissipating any energy.

Below is the correct way to make this mod. Bob, do this and then tell us what you hear ...

Regards,

Jerry

http://www.classicspeakerpages.net/dc/user_files/1901.jpg

[joelongwood]

Thanks, Jerry, but I must have an earlier version of the 3a, because, while the tweet pot wires are identical to the diagram, on the mid pot, there is only one wire (green) attached to the top ( of the pot. There is no sign of any other wire (the one labeled "choke" in the diagram. Can I just take the green wire off the top ( of the pot and attach it to the connection where the other green wire is on the pot?

Thanks again for your help.

Bob

[onplane]

>Thanks, Jerry, but I must have an earlier version of the 3a,

>because, while the tweet pot wires are identical to the

>diagram, on the mid pot, there is only one wire (green)

>attached to the top ( of the pot. There is no sign of any

>other wire (the one labeled "choke" in the diagram.

>Can I just take the green wire off the top ( of the pot and

>attach it to the connection where the other green wire is on

>the pot?

>Thanks again for your help.

>Bob

Sorry, Bob! I misread your post and thought you had AR-3's NOT 3a's!

In any event, you are correct and below is the drawing for 3a's. (In short, on the mid-pot, you cut the green wire and solder to the same terminal that the coil is soldered. On both pots, you leave the terminal with the YELLOW wire as it is.)

Regards,

Jerry

http://www.classicspeakerpages.net/dc/user_files/1902.jpg

[joelongwood]

Geez, Jerry, either I'm getting old (fact) or I have too many AR's (also a fac)t...........BUT, my question does indeed involve AR3's.....NOT 3a's, even though I incorrectly stated that in my second post. In any event, I just soldered the two green wires to the #1 terminal on the mid pot and compared the sound to the other speaker which merely has the pots jumpered.

I can hear a very slight increase in the treble response with the one I bypassed, but the mids are pretty much the same. Is the 3 midrange that much more muted than the 3a midrange, or is it the higher crossover in the 3 that is sending much of the lower midrange to the woofer, resulting in less output from the midrange driver?

The problem is solveable, because I happen to have a pair of Micro Acoustics Microstatic tweeter arrays which I hooked up to the 3s.............and the sound now is much closer to the 3a's.

I've read a bit about your passive bi-amping, and I happen to have quite a few amps/receivers around, so I think I'd like to try it. I'd appreciate it if you could point me to the thread which gives step by step instructions for testing the amps for compatibility and also for the correct hookup procedures.

Thanks for all your help, you've been great!

Bob

[onplane]

Bob, I'll show the passive bi-amping scheme in this thread, as I have some nice diagrams. As you know, you do have to verify that the amps are compatible. Again, I’ll explain in this thread.

Before we do anything, however, I’m a little concerned about your mid-driver. You should be getting plenty of sound out of it now. The fact that you don’t makes me concerned that the driver is bad OR the cap is bad.

One simple test you could do is connect your amp to terminals 1 and “T” on the speakers and remove that strap that runs from “T” to 2. Now, turn volume all the way down and bring up … slowly.

Bob, what we are doing here is powering nothing but the tweeter and mid. You should hear plenty of sound out of the mid. If you don’t then the mid is shot OR the cap is shot. Something is clearly wrong.

Let us know, Bob, what happens with this test.

Regards,

Jerry

[joelongwood]

Jerry, I think the mid is fine........I had been listening to XM Radio, a highly compressed source which is definitely lacking in midrange frequencies. I just put on some CDs and the mid is definitely putting out decent sound, in some cases too much! It produces a bit more than the mid on the other speaker that is merely jumpered. Now I have to bypass the pots on that speaker so I can passively bi-amp.

You can give me directions whenever you're ready........thanks so much.

Bob

[onplane]

Bob, that's good news on the mid-driver! Once we passively bi-amp, you'll have complete control over the energy balance between the woofer and the mid/tweeter.

Next step is to measure the amps you want to use. What we are looking for is common "ground" amps and 99% of the amps are designed this way.

To test you need a multi meter. Then you put one probe on the black speaker output and the other on the ground shield on any input jack. You set the meter to read ohms and we are looking for a reading of zero ohms or very close to zero.

Once both amps pass this test, below is the wriring diagram. Just make sure you REMOVE that strap on the speaker between "T" and 2. Also make sure that you twist together the two wires coming from the black speaker outputs and connect to terminal 1 as shown below.

To connect the amps together, I suggest you use tape OUT on your primary amp and aux on the secondary amp. This way the primary amp alone selects the music source.

Now, once everything is connected, turn the volume all the way OFF on both amps. Then SLOWLY raise the volume on the amps powering the mid/tweeter and make sure no sound comes from the woofer. Then turn this volume control full off, and SLOWLY raise the volume on the amp powering the woofers. This time you should hear NOTHING from the mids or tweeter. If OK then slowly raise the volume on the mid/tweeter amp until it's balanced to your liking.

Bob, let us know how you make out.

Regards,

Jerry

http://www.classicspeakerpages.net/dc/user_files/1903.jpg

[joelongwood]

Thanks again for your all your help and patience, Jerry. I'll try and do the bi-amping over the next few days, and I'll let you know how I make out. For the woofers I'm planning to use a Carver 6250 receiver that puts out 125 watts RMS per channel from 20-20,000. For the mid/tweeter, I'd like to use, as you have suggested, a lower power unit, such as a Yamaha CR-220, a Sansui R-303, or an Advent 300 Receiver, all around or under 30 watts per side. I'd like to do this tomorrow, but I'm meeting someone to pick up more speakers (I can't stop!)........another pair of AR2ax, another pair of AR4x, a pair of KLH 6, and a pair of Dynaco A-25, everything in supposedly great condition. All for $100 and a 30 minute drive............how can I say no?

Bob

[onplane]

>I'm meeting someone to pick up more speakers (I can't

>stop!)........another pair of AR2ax, another pair of AR4x, a

>pair of KLH 6, and a pair of Dynaco A-25, everything in

>supposedly great condition. All for $100 and a 30 minute

>drive............how can I say no?

>Bob

>

How do you guys do it??

My wife would have no problem saying, "NO!" She does it all of the time!

Bob, I like your options on amps, Bob!! That Carver will tame those woofers and the other amps will make the mids/tweeter "sing".

Regards,

Jerry

[joelongwood]

Well, I finally got around to passively bi-amping the AR-3s today. The woofers are hooked up to an Onkyo receiver putting out about 75 watts into 4 ohms, and the tweeters are being driven by a small Sansui receiver. Unfortunately, I did everything on the floor, which does not make for an ideal listening experience, but, after only a few moments listening to FM, I can tell that this is definitely a good thing. And I have yet to try it with a better source, such as CD or vinyl. The main reason I like this set-up (at least for me and my 58 year old ears) is the total control over the sound balance between the woofer and the mid/tweeter, and the ability to raise the mid/tweeter levels to my liking. As I've mentioned previously, I found these 3's to be rather dull sounding. Even bypassing the tweeter pots and soldering the mid to the top of the pots did not seem to yield enough high end for these old ears. Maybe the 3's need new caps or something, because I don't find my 3a's deficient in the high end. As a matter of fact, on the 3a's, I have the tweeter control almost all the way up, and the mids are set very slightly above the dot. I can't imagine the 3's are that different in the mid/high end than the 3a's, but my pairs are most definitely very different in that area.

In any case, even set-up in a less than optimum space (on the floor), for the 3's at least, this set-up is a keeper. Not being a purist (I have a number of equalizers and actually use them.......I know, to many of you that is heresy!), I find this passive bi-amping provides for a more enjoyable listening experience......not only are there more highs and mids in relationship to the woofer output, but the bass seems a bit tighter as well, although this might just be my imagination. Overall, there is, to my ears anyway, a much more balanced sound coming out of those boxes.

Thanks, Jerry for all your help, it's greatly appreciated.

BTW.....picked up those speakers I mentioned earlier, except the guy was mistaken on a few of them.....instead of 4x's they were Dynaco A25xl's, and instead of the KLH 6, it was the 17. So, for $100, I brought home a pair each of Dynaco A25, A25XL, AR2ax (needing foam), and KLH 17's. All of them work flawlessly (except the A2ax, of course). I stacked the Dynacos tweeter to tweeter vertically........great sound! But these bi-amped 3's are gonna give that stack a run for the money.

Bob

[onplane]

>

>The main reason I like this set-up (at least for me and my 58

>year old ears) is the total control over the sound balance

>between the woofer and the mid/tweeter, and the ability to

>raise the mid/tweeter levels to my liking. As I've mentioned

>previously, I found these 3's to be rather dull sounding.

>

>I find this passive bi-amping provides for a more enjoyable listening

>experience......not only are there more highs and mids in

>relationship to the woofer output, but the bass seems a bit

>tighter as well, although this might just be my imagination.

Bob, since you are NOW bi-amping, you could (as I do) by-pass the mid-pot as well. This will gain about 1db in the mid ... not a lot, but … some.

Next, I totally agree with you. The ability to CONTROL the balance is one of the HUGE benefits of passive bi-amping.

Now, as for the tight bass, I don't think it's your imagination as I experienced exactly the same thing. The bass is so much tighter that I took my AR's off the stands and PUT back on the floor. It's NOT the least bit "boomy", which is why I put them on stands in the first place. I do, however, angle them back just a tad so that the tweeters point towards my normal listening position.

When you get a chance, Bob, please compare the bass of the bi-amped AR-3’s against the bass in the single amped AR-3a’s. Then, as always, please share with us what you hear.

Finally, Bob, congratulations on a successful mod and a successful "Jerry-rig"!

Regards,

Jerry

PS: I've found that you can achieve small improvements by turning the treble control full OFF in the woofer amp and the bass control to 9:00 o'clock in the mid/tweeter amp. (This also gains you terrific "headroom" in that small amp.)

Next, the addition of a small lamp cord patch between the amp common grounds provides more current return options for the woofer and got me a small improvement in bass (see below). I believe this is due to the small resistance found in those speaker selection switches.

http://www.classicspeakerpages.net/dc/user_files/1933.jpg

[joelongwood]

OK, Jerry, I hooked them up in their original place, about 3 feet off the ground on top of a pair of rather large Cerwin Vega AT-100's. Their backs are about two inches from the rear wall, and both are at least three feet from the nearest corner. I also hooked them up using different amps.....a Carver 6250 Receiver for the woofer and an Advent 300 for the mids/tweeters. Again, the sound is wonderful.....full, rich, excellent non-boomy bass, coupled with a crisp, detailed, yet smooth mid/top end. I would never have believed the improvement unless I actually heard it for myself.....thank you for your patience and all your help in helping me to achieve this.

I have read just about all of your previous posts, so I already had the bass turned down on the mid/tweeter amp, and the treble turned down on the woofer amp. But, now I set the mid/tweeter amp at 9 o'clock as per your instructions. I don't really hear much of a difference, if any........should I? If anything, the sound is ever so slightly "fuller."

The Carver receiver I'm using for the woofer has a mid-range control as well, and I believe it's centered at 1000 hz. I needed to turn that down to about the 10 o'clock position, or there was too much lower midrange.......the sound was too "thick" for my liking.

Also, I think I'm going to leave the mid soldered to the top of the pot.....it sounds perfect to me as is.....plus I really don't want to go back in there.

A side-by-side comparison with the AR3a's is doable, but it'll be awhile. The 3a's are kind of difficult to get at right now (they're under a pair of AR5's and AR4's.......and the wires are kind of a mess. But when I get a chance I'll A/B them for bass response.

Thanks again, Jerry........you and the people on this site haved provided me with, not only a vast array of useful information (well, most of my friends and my wife would disagree with that), but it's also a helluva nice place to visit.

Bob

BTW.... the stack of Dynacos will have to sit on the sidelines for awhile.

[onplane]

>I have read just about all of your previous posts, so I

>already had the bass turned down on the mid/tweeter amp, and

>the treble turned down on the woofer amp. But, now I set the

>mid/tweeter amp at 9 o'clock as per your instructions. I don't

>really hear much of a difference, if any........should I? If

>anything, the sound is ever so slightly "fuller."

>The Carver receiver I'm using for the woofer has a mid-range

>control as well, and I believe it's centered at 1000 hz. I

>needed to turn that down to about the 10 o'clock position, or

>there was too much lower midrange.......the sound was too

>"thick" for my liking.

Bob, the issue with the bass control is that on some receivers the bass control center frequency is around 100Hz. (My guess is yours is probably closer to 20Hz, which is ideal.) In any event, for the receivers/amps with a 100Hz bass control, if you shut BASS all the way OFF, we could be "starving" the mid driver in the 500 - 900Hz range.

Bob, try a simple test. Shut the woofer amp OFF (select an empty source). Then with just the mid/tweeter amp running turn the BASS control from end to end. If you can hear NO difference, you have a very good control and can leave if full OFF.

My mid/tweeter amp is a real cheapie "chip amp" and I need just a tad of lower mid range to insure proper balance.

Also, Bob, try the zip cord patch (connect all the black common grounds together at the amps). If your amp has even slightly dirty speaker selection switches, you'll hear a very slight improvement in the deepest bass.

Regards,

Jerry

[joelongwood]

OK, Jerry, here's what I found. First, the Advent 300 I'm using for the mid/tweet has a bass turnover frequency of 100 hz........just like yours. I tried the test, and I can definitely hear a difference when turning the bass control from full off to full on......9 o'clock is just about right. I have quite a few low powered receivers around, and I checked the specs, but the onkly one that's close is a Sherwood which has a bass turnover of 50 hz. All the others are at 100 hz or above. I'll probably just leave the Advent there as it's quite small and unobtrusive.

I'll try the lamp cord patch and report back.

Bob