one newbie question

[Guest Mullard]

I just bought a pair of AR4x, and the sound field is off the position compare to my Magnepan MMG. I saw both tweeters are on the same side.

The seller told me that, because the designer of these speakers in 1966 did not make them in a mirror image (a designated left and right) to satisfy a buyer of used equipment 30+ years after they were made. As for the Dynaco A25, they also are not a mirror image speaker.

Anybody who can tell me some more bed time stories, I'll be very happy to hear it Should I replace them side way?

[tysontom]

>I just bought a pair of AR4x, and the sound field is off the

>position compare to my Magnepan MMG. I saw both tweeters are

>on the same side.

>The seller told me that, because the designer of these

>speakers in 1966 did not make them in a mirror image (a

>designated left and right) to satisfy a buyer of used

>equipment 30+ years after they were made. As for the Dynaco

>A25, they also are not a mirror image speaker.

>Anybody who can tell me some more bed time stories, I'll be

>very happy to hear it Should I replace them side way?

Basically the seller's tale is nonsense. The AR-4x speaker is a reverberant-field speaker, designed to disperse the sound evenly throughout the listening environment, and to give the illusion of spaciousness and three-dimensionality. This they do very well, especially for their modest cost. I believe that they have flatter acoustic-power radiation than the Magnepans, because the latter have poor off-axis response at the highest frequencies. AR-4x's were never intended to "image" or to be designed as "mirror-image" speakers. The benefits of such designs were not much of a consideration in 1966, but continue to be debated even to this day. The jury is still out.

The Magnepans are directional speakers with a slight "figure-eight" radiation pattern, designed to be listened to basically in one "sweet spot" location. They "image," if that is the important criteria, far better than the AR-4x. As you go off-axis from that spot, however, the Magnepans begin to sound somewhat flat and two-dimensional, and lack depth and spaciousness, because the panel's radiation surface is relatively large in relation to high frequencies. I know because I owned a pair for a few years some time back.

So what do you do with the AR-4xs? If you want them to sound like the Magnepans, forget it and get rid of them. If you want them to sound like they were intended to -- which is to reproduce music accurately -- place them on a bookshelf with books around them or counter (up off the floor) close to the back wall, and go about your business while listening back in the room in any position. You certainly don't fret over the proper position of the one chair in which to find the sweet spot. But before you do anything with them be sure that the level controls are clean and working properly. This can cause level and frequency-balance issues between the left and right channels.

--Tom Tyson

[Guest Mullard]

Thank you very much Tom. I feel that AR fans are group together way strongly than others. I feel happy to be here. Thanks for your time, and it's fun to read your reply.

[Rlowe]

Tom,

You use the words "reverberant-field" for the AR-4x speaker.

Is it true to say all AR speakers are designed this way or were there exceptions?

[tysontom]

>Tom,

>

>You use the words "reverberant-field" for the AR-4x speaker.

>

>Is it true to say all AR speakers are designed this way or

>were there exceptions?

>

The AR-4x was like all of the earlier AR speakers in that it was designed to have the widest-possible dispersion throughout its operating range. AR felt that in order to recreate the illusion of the concert hall (for example), the loudspeaker should exhibit an acoustic-power output in the listening room similar to the reverberant energy in a concert hall. If you try to listen up close to a pair of AR speakers with wide dispersion, the "image" is disrupted to some degree because of interference effects from walls, cabinet edges and other items close to the speaker. The image seems vague or less focused compared to a speaker with known good imaging. Yet, as you get back in the room and into the reverberant field, this "destructive interference" is largely nullified due to cancellation effects and is swamped in the reverberant field, and the wide-dipersion speaker takes on a degree of spaciousness and realism that directional speakers don't exhibit.

This AR philosophy of wide dispersion continued well into the late 1980s and even into the 1990s with the AR-303, etc., which basically replicates the same philosophy with a modern-day approach. More recent AR speakers are probably more directional, as many audiophiles have bought into the "imaging" approach, regardless of whether or not it was more realistic or accurate. "Accuracy" should not be a matter of taste, but unfortunately the science of high fidelity has given way to the art of golden-eared sound (e.g., *Stereophile* magazine). Of course, I am not opinionated!

--Tom Tyson

[Guest Mullard]

Tom,

One more quick question please. In all collectable AR single digit speakers, Which model has the most powerful bass? AR1 or AR9? Thx.

[tysontom]

>Tom,

>

>One more quick question please. In all collectable AR single

>digit speakers, Which model has the most powerful bass? AR1 or

>AR9? Thx.

The AR-9, by a large margin. It has the attributes of the AR-1, but more of it with a lower bass resonance and roughly double the power-handling capability. This means that it will go lower, with lower distortion, than the AR-1 or any of the single-woofer, 12-inch AR speakers. The AR-9 is also "heavier" sounding than the AR-1, so placement of the speaker in the listening room is important to avoid an excess of a good thing.

--Tom Tyson

[Guest Mullard]

Tom,

After many A/B testing and AR manual reading, I am totally agree with you. AR is designed to disperse the sound evenly throughout the listening environment, and to give the illusion of spaciousness and three-dimensionality. Thank you for point that out, I didn't know that I was look for Magnepan's crossfire sweet spot. AR has some good benifits that Magies't have. think that I'll collect several more pairs of single digit AR, and I love them and the way they designed. Have a good weekend.

Mullard

[Guest palomar]

Tom,

I have a question concerning the dispersion characteristics of the Large Advent vs the AR2ax. I believe (and please correct me if I am wrong) that you indicated in another post somewhere that whereas the ARs were designed more for overall neutral characteristics in combining on- and off-axis response, Henry Kloss designed the Large Advent for more neutral response on axis.

The Advent and AR both had 10-inch woofers. But the AR crossed over to its 3.5 inch mid range driver at 1400 Hz, and to its 3/4 inch tweeter at 5000 Hz. The Advent crossed over to its tweeter at 1000 Hz. I don't remember the exact size of the Advent's tweeter, but I think it might have been about 2 or 2.5 inches with the center radiating part about 3/4 inch.

Because of the lower crossover and smaller size of the Advent's tweeter (vs the AR's midrange), wouldn't the Advent actually have better dispersion in the upper midrange to lower highs than the AR? And would it be about a wash at the upper frequencies given the AR's 3/4 inch tweeter and Advent's 3/4 center radiating shell?

By the way, I happen to like the sound of the ARs better (which may the key to this whole thing). To me, they sound smoother. I always found the Advents (which I also like) to be a bit bright in the midrange. (Just my opinion - I know many listeners prefer the Advents.)

Thank you.

[Steve F]

Yes, the Advent did indeed cross over to its tweeter at 1000Hz, a shade sooner than the 2ax crossed over to its 3 1/2" midrange. But that was not as big a deal as it might seem at first glance.

Two things to keep in mind here:

1) 1000 Hz is not much different than 1400Hz, acoustically. It may seem like a big difference numerically ("What?! 1400Hz is 40% HIGHER in frequency than 1000Hz—that’s a HUGE difference."), but that’s not really the way it works. The ear really reacts to sound in octaves, which is the halving or doubling of frequency. When you go up or down the musical scale (you know, like doe, ray, mi, fa, so, la, tea, doe), the doe’s are an octave apart. One doe is double or half the frequency of the other doe. So an octave above 1000Hz is 2000 Hz, and as you can see, the 2ax’s 1400Hz crossover point is not all that much higher than the Advent’s 1000Hz. Sometimes, this concept is a little difficult for people to grasp (because the numbers seem counter-intuitive), but that is how humans react to sound.

2) Despite the Advent tweeter appearing to have a small domed center portion, it was, in fact, a conventional cone driver, with the voice coil at the center of the cone and a suspension around its periphery. The center "domed" portion did not de-couple from the rest of the unit and somehow magically act as the sole radiator of the very highest frequencies, nor did Advent claim that it did. AR developed its 3/4" dome tweeter for wide dispersion of the very highest frequencies specifically because conventional tweeters—like the Advent’s—did NOT behave as small radiators at the high frequencies. The Advent tweeter was a very good, conventional cone tweeter of approximately 2 1/2" diameter, with good power handling and a commendably wide range.

The Advent was voiced by Andy Petite (changed back later to Andy Kotsatos, his original Greek family name) to have a very specific octave-to-octave balance, with primary emphasis on first-arrival, on-axis frequency response. Reverberant-field energy response was not Petite’s (or Henry Kloss’) design goal. AR (Roy Allison and Ed Villchur) took a different approach and they believed that total radiated acoustic energy was the primary factor in determining how convincingly realistic and accurate a speaker would sound. I have posted some very long entries on this Advent-AR/Kloss-Villchur design philosophy subject before, and I’d be happy to point you to them if you’re so inclined.

Steve F.

[Guest palomar]

Steve,

Thank you very much for anwering my question. I would be very interested in reading your posts regarding AR/Advent design philosophies.

Gary

[Steve F]

Gary,

There are several excellent posts in a thread entitled "EV vs. HK Design Philosophy." EV of course was Ed Villchur, and HK was Henry Kloss, of AR and Advent respectively. The thread is dated from December 11, 2002, and Tom Tyson and myself have several long entries (#’s 1540, 1541, 1542, 1546, and 1552), as well as several other excellent entries from other Forum contributors. This thread will give you a very comprehensive and accurate picture of the different ways that AR and Advent designed and marketed their products.

Steve F.

http://www.classicspeakerpages.net/dc/dcbo...&mode=full#1541

[Guest palomar]

Steve,

Thank you very much for the posts. I found them extremely informative.

Gary

[Guest Mullard]

Dear Steve and Tom,

I found out that I am in love with AR4x, and I decied to get another pair soon. My power amps are Quad II, and each monoblock does 4 to 8 ohms. My goal is put two AR4x on each Quad II amp by Parallel not in Series. So two AR4x by Parallel will be 4 ohms ((1/8 + 1/8)then inverse equal 4 ohms). Quad II should be still work fine, right?

I could put two AR4x together either L ot I letter shape for different sound fields, and of course I won't place them at 4 corners.

Will this work out fine? I reaaly need your expert experience, advice, and suggestion. Thank you so much, I really want to use AR4x and make other people jaw drop by my vintage system.

Sincerely

[tysontom]

>Dear Steve and Tom,

>

>I found out that I am in love with AR4x, and I decied to get

>another pair soon. My power amps are Quad II, and each

>monoblock does 4 to 8 ohms. My goal is put two AR4x on each

>Quad II amp by Parallel not in Series. So two AR4x by Parallel

>will be 4 ohms ((1/8 + 1/8)then inverse equal 4 ohms). Quad II

>should be still work fine, right?

>

>I could put two AR4x together either L ot I letter shape for

>different sound fields, and of course I won't place them at 4

>corners.

>Will this work out fine? I reaaly need your expert experience,

>advice, and suggestion. Thank you so much, I really want to

>use AR4x and make other people jaw drop by my vintage system.

>

>

>Sincerely

>

You can certainly wire two 8-ohm AR-4x pairs in parallel (two on one channel and two on the other channel) to get close to 4 ohms/channel. The Quad monoblocs should drive this combination fine I would think, but they will generate more heat due to the lowered impedance. The AR-4x is a relatively stable load, so this combination works well. Probably the best way to do this would be to place two AR-4xs on top of one another, *vertically,* with the woofer down on the bottom speaker and the woofer up on the top speaker (you could invert to see which you prefer). You can angle-in each pair of speaker slightly towards the listening position, if you wish, but put felt pads or a similar substance to "isolate" each cabinet. Keep them at least one foot or more off the floor and preferably out of the corner, but fairly close to the back wall in the traditional "left-right" stereo configuration. Mounting them on a shelf or table is probably the best way. The stacked configuration gives a sort of "line source," and woofer output is also augmented somewhat by a phenomenon known as "mutual radiation impedance," whereby the woofer output is increased by approximately 3 dB. The resonance frequency is not lowered, but the bass output and power-handling is increased and the speakers will have a "warmer" sound.

Several years ago a friend of mine had stacked AR-4xs, driven by an early AR Amplifier. He would occasionally play this combination at high levels, especially after a few drinks, and the sound was always very impressive. The AR amp would get so hot that you could not touch it -- but it never failed -- which truly amazed me. Many people used to stack Advents for this very purpose, but the AR-4x benefits in the same way.

--Tom Tyson

[Steve F]

The idea of using double AR-4x’s per channel is an interesting proposition. I do not have any first-hand experience with your Quad amplifier, but if it’s comfortable running a 4-ohm load, then paralleled 4x’s on each channel should not pose a problem. Unlike so-called “8-ohm” speakers produced from the 1990’s onward, the 4x’s were, in fact, nominally 8-ohm units, and running two should be pretty safe.

(As an aside, by about 1985-1990, the audio industry had become so competitive that the speaker that sounded louder during an A-B comparison in the store showroom would inevitably sound better—and therefore sell better. At that point in the history of audio retailing, the hobbyist mentality was beginning to fade very rapidly, so most stores had abandoned their use of the “efficiency comparator” that compensated for differences in speaker efficiency during an A-B test. In an effort to make their speakers sound louder during uncompensated demonstrations, most companies’ speakers were blatantly 4-ohm speakers, and the “8-ohm” label was an outright, um, shall we say, “fabrication.” Woofers were 4-ohm-units; speakers that used 2 woofers usually used two 7-ohm woofers in parallel; if it was a three-way speaker, you had two paralleled 7-ohm woofers (3.5 ohms) crossing over to a 4-ohm midrange. Depending on the crossover design and how much the drivers’ operational frequency range overlapped, often an “8-ohm” speaker’s impedance dropped to BELOW 3-ohms, right in the heart of the midrange. Scores of cheap $300 Sony and Technics receivers have been cruelly toasted as a result.)

As to how to configure your 4x’s, I’d recommend you start by stacking them vertically on each other, with the woofers top and bottom and the tweeters in the middle, with the lower speaker about 12” off the floor. This arrangement will give you the least amount of random destructive interference between the drivers. Note that with the tweeters in, they will exhibit some restriction of dispersion in the vertical plane (not unlike early THX-certified speakers which were intentionally W-T-T-W, specifically to restrict vertical mid- and high-frequency dispersion), but the horizontal dispersion will still be relatively unfettered. In addition, mounting them this way brings both tweeters to around seated ear height, a desirable objective.

Each 4x will only be driven one-half as hard for a given SPL as compared to a single-4x-per-channel system, so the overall distortion from the speakers will be somewhat lower. I don’t know how much power your amplifier has, but you might even be able to apply some very modest LF EQ to your speakers, since each unit is not being driven particularly hard. Be very cautious about this, however: every 3 dB increase in EQ represents a DOUBLING of amplifier power, so you could run out of power very quickly and push your Quad into early distortion, thereby negating whatever benefits you might otherwise have enjoyed from your doubled-up 4x’s. Also, keep in mind that there is a real limitation to just how much bass you’re ever going to be able to coax out of a 4x, regardless of EQ setting or amplifier headroom.

Also keep in mind that my comments are being made in the abstract; you may prefer the speakers in a different orientation than I’ve suggested; your amplifier may have more or less capability than you need; and you always need to be cognizant of the practical considerations of physical stability, so the speakers don’t fall over and damage something—or someone!

This is just a hobby—experiment and enjoy yourself..

Steve F.

[Guest Mullard]

Thank you very much Steve and Tom. You both point out lots of detail information. Especially every 3 dB increase in EQ represents a DOUBLING of amplifier power. I did toast my roommate’s cheap Sony receiver before by 6 surround speakers on two channels.

After both AR experts’ words, I am running one mono amp with two AR4x two hours already with normal volume. Quad II is working fine, and there is no over heats up situation happen, but it does warm up faster than running one AR4x. I will run again with higher volume for second experiment after amp cool down. I am happy with AR precise impedance compare to modern mass market speakers. I’ll be enjoy about vintage AR speaker hunting again. I got a bit greedy now. Should I get a pair of AR2 or AR2ax instead of second pair AR4x? Or should I stick with original plan with two pairs of AR4x? One more question, should I add Fusetron dual-element type FNM 6/10 fuses to protect AR4x? OR should I lower the fuse on Quad II? I am very pleased every time when I read your replies. You two are truly audiophiles unlike those people who believe expensive system can get better sound.

Quad II spec:

The matching speakers are Quad ESL-57 ELECTROSTATIC SPEAKERS.

15 watts throughout the range 20-20000 c/s

Frequency response within 0.2db 20-20000c/s, 0.5db 10-50000c/s

Background: 80 db referred to 15 watts

Distortion(measured at 12 watts output):

Total 3 rd and higher order: less than 0.1% at 700 c/s

Higher order alone: less than 0.03% at 700 c/s

Valve mismatching up to 25% (introducing 2nd harmonic) not to cause distortion to exceed 0.18%.

Total distortion at 50 c/s

The Quad II was originally configured with 15 ohm output impedance, but my Quad II been modified to 4 to 8 ohms by changing a couple of tags on the output transformer.

website for speaker and amp information:

http://www.geocities.com/ResearchTriangle/...ad22quadii.html

http://www.audioreview.com/speakers/main-s...87_1594crx.aspx

[tysontom]

>

>Quad II spec:

>

>The matching speakers are Quad ESL-57 ELECTROSTATIC SPEAKERS.

>15 watts throughout the range 20-20000 c/s

>Frequency response within 0.2db 20-20000c/s, 0.5db

>10-50000c/s

>Background: 80 db referred to 15 watts

>Distortion(measured at 12 watts output):

>Total 3 rd and higher order: less than 0.1% at 700 c/s

>Higher order alone: less than 0.03% at 700 c/s

>Valve mismatching up to 25% (introducing 2nd harmonic) not to

>cause distortion to exceed 0.18%.

>Total distortion at 50 c/s

>

>The Quad II was originally configured with 15 ohm output

>impedance, but my Quad II been modified to 4 to 8 ohms by

>changing a couple of tags on the output transformer.

>

Well, for some reason I was thinking that this model Quad was a higher-output solid-state design, not tube-type. My mistake. The 15 watts/ch concerns a bit, as your maximum peak-power capability is likely 30 watts/ch, short-term. No real problem except that you can easily tax (and possibly "clip" the output) of a 15-watt amplifier if you like to play your music at pretty high levels. Particularly with the AR-4xs in parallel, the tendancy will be to run them at higher levels. So the caveat is to treat this combination with respect and not play particularly loudly, as 15 watts will be used up quickly. Over-exurberance can lead to amplifier clipping, generally regarded as deleterious to the health and safety of the tweeters.

My friend's setup years ago with two AR-4x/ch with the AR Amplifier showed me that the little AR-4x speakers could handle a lot of power when paralleled, so the tendancy was to play louder and louder, pretty much in direct proportion to the Scotch & Sodas being consumed. At times he was driving the ouput almost to the point of distortion, and I'm thinking that he was easily exceeding 100+ watts/ch peaks on the AR amp, which was known to be capable of >90 watts/rms/ch into 4 ohms.

Keep this in mind with your 15-watt-per-channel amplifier.

--Tom Tyson

[Guest Mullard]

Tom and Steve,

Thanks for your time about answering questions all the time, and I learned lots of audio things from you two. Just wondering could you send me your home address to my e-mail account? I have one little gift and information about AR that I want you two to have. thanks again.

my e-mail account is: impreza420@yahoo.com