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ReliaBill Engineer

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  1. ReliaBill Engineer
    So we’re back in the Mids and Tweaks back alley. Someone please describe the difference in performance between the paper cone midrange used in the early 2ax, and the dome midrange used in the early 3a….. Descriptions and/or plots and measurements are all fine for answering.
  2. ReliaBill Engineer
    The titles of the clips are dead give aways:
  3. ReliaBill Engineer
    Nearfield recording vs further back in the room also makes a difference. It’s a lot like most people preferring the louder of 2 playbacks. As for the Hello Dolly recording, I don’t know which recording you’re listening to. Digital or analog. You didn’t hear it with whatever you’re listening through and from. From the album, it’s actually at 1:14-1:16 primarily in the left channel. I figured you’d hear it on your way into the 1:30 mark. My mother was a perfectionist. It bothered her. I hear it from the dome mids in my room, and over my headphones, and first heard it from my Polks several years ago. In ‘65-‘66 my dad had the AR-2ax’s and couldn’t hear it. But, he was using a Shure M44C cartridge also. I couldn’t hear it over these stock AR-2ax’s. My dad reminded me of the history associated with that album, at least in our household.
  4. ReliaBill Engineer
    Not a tweak or mod. Just an attempt at comparison. There is a story behind that Glenn Miller album. I can remember my parents having a heated discussion about it. My mother worked for Columbia Records when that album was recorded/mastered/pressed. As the QC Supervisor of the California pressing plant, she raised the issue of a mistake made during recording of “Hello Dolly” with Columbia Executives. The decision was made not to re-record it. Prevailing opinion at that time was that home listeners won’t be able to hear the mistake. In ‘66 my dad’s system wouldn’t reveal it. Stock, these 2ax won’t either. But if you pull up the original soundtrack, at 1:30 into it, you’ll hear one of the trombone players hit the music stand in front of him! That’s why my mom brought that recording home, and my dad was adamant that my mom was making a big deal, risking her job. She didn’t lose her job. She was promoted, and trained the new hires for the new Santa Maria CA pressing plant.
  5. ReliaBill Engineer
    This isn’t about room placement nor equipment. It’s not a show of someone’s “system.” It’s not about someone’s choice of music media. Suffice it to say, identical equipment was used for both, except for the midrange driver. It's just a comparison of midrange drivers. It’s my attempt to keep the AR sound character, yet use a mid driver that has better dispersion, a less strained sound, and render more detail from the recording. I listen to 95% vinyl sources, so that is what I used for comparison. In my experience, it is entirely possible to keep the AR sound, but also add more fidelity, and remove some listener fatigue. Those paper cones wear on me after a while. I’m convinced that’s the reason AR added the fiberglass padding.
  6. ReliaBill Engineer
    Both are from the same track on this original 1965 Epic vinyl record. Passed down to me from my parents. No electric bass. Played using the Shure V15V-MR cartridge.
  7. ReliaBill Engineer
    If you *looked* at the videos, you’d see the stock midranges on one video vs the domes on top of the cabinets in the 2nd video.. And “Thank you!!” The fact that the 2 videos sound so much alike is a complete validation of my efforts! Very difficult to capture the entire differences using a cell phone. And yes, I know that there will be differences from speaker placement, together on the floor vs on 20” stands 8’ apart. But my point is that the domes blend so well with the AR tweeter and woofer, and achieve/keep the original sound character! Yet….In the actual room one can hear so much more detail from the recording and so much more “air” to the sound using the domes, vs the colored and directional sound from the paper cones. To capture a better sample from my cell phone, with less room interaction, I toed the speakers in to my standing position between them. Normally I listen with the speakers facing directly forward. There are no “crossover mods.” Same 6 uF caps and same 16 ohm pots as used with the original AR paper cone mids. Fact is, all I did was clip the green and yellow wires from the paper cone mid and attach them to my dome leads. The paper cone mids are out of the circuit entirely. I used weatherstripping foam gasket that allowed me to pass the wires behind the paper cone mids, yet keep the airtight seal.
  8. ReliaBill Engineer
    For comparison. How can anyone make a comparison of changes made, using 2 entirely different tracks?
  9. ReliaBill Engineer
    Well, I went back and moved my original AR pots to their original positions. On my first speaker recap of the 2ax pair, after cleaning the pots, I moved them so the “dot” was exactly midway in the total rotation of the pot knob. As RoyC later advised, it wasn’t a good move. Agreed! So now both speakers have both pots in their original positions. And now I run both speakers with mid and tweeter pots in their “home” dot positions. I documented my midrange mod in the “Tweaks and Mods” section of the forum. Goal was to have the same sound as the original 2ax drivers, just cleaner, with more detail. That goal has been totally realized. But I did run into the same sort of issue that AR did with its paper cone midrange, namely that the top registers of sound were peaky and ragged. Same issue with the dome mid I selected. I chose an inductor to roll off that raggedness of the 2” dome. But regardless, I ran into the same issue that AR engineers did 58 years ago. So, full circle, I ran into the same issues that AR did, and answered my original question of “why the FG pad over the midrange driver?” Just a comparison. I chose a 1965 record of The Glenn Miller Orchestra on Columbia’s Epic label for jazz. My experience is that these records are recorded “hot.” They can be fatiguing over long listening sessions. But here, the pots are at their “dot positions” for mid and tweeter. Original crossover values, original pots, original internal rock wool damping. Not much difference in sound character between mids (domes vs paper cones) other than smoothness, dispersio, and level of detail. (Domes are wired to the internal wires for the original mids, the yellow and green wires. Polarity of dome reversed the same as original mid and tweet. Using internal crossover and pot.)
  10. ReliaBill Engineer
    Just some sound samples. Such a big, effortless sound! Longer track. Linda Ronstadt: Shorter track, also Linda Ronstadt: And, for contrast, the squawky AR paper cone midrange: Same track as above, 1965 Glenn Miller Chattanooga Choo Choo:
  11. ReliaBill Engineer
    Next, these will get the expanded aluminum grills, to keep with the AR midrange driver “motif.” And BTW, yes. I did remember to reverse the polarity of the midrange dome driver. I love the effortless, airy sound! I can listen for hours on end, with no irritation or fatigue. When complete, this will look the part of an AR driver, look right at home! But belie the squawky, numb sound these had. All my goals will have been met.
  12. ReliaBill Engineer
    So the next step…. I tied in to the original AR crossover network. Using the internal 6 uF capacitor and 16 ohm pot (rheostat). Plus my shaping network at the midrange dome. Added a foam ramp in front of the dome to deaden diffraction from the front edge of the cabinet top. But in alignment with the VC of the original midrange. Used foam weatherstrip to reseal the original mids and allow passing wires from behind the mids. Seal was good by using the “pressing the woofer cone” technique. I played some Epic label Bobby Hackett trumpet music (playing Bert Kaempfert’s hits). These can sound hot or squawky on different speakers, especially so using the Shure V15V-MR cartridge. I think it sounds great! My wife actually noticed the difference, and began dancing in the living room! These sound very smooth, neutral, detailed, and very airy, with a huge spacious sound. Imaging is tremendously wide and deep, not 1-dimensional. I’ve found that these mid domes sound best at a 65% setting on the pots. Tweeter at 85%. And yet, still very much the AR sound. Just a whole lot less colored and squawky. And, now I can lose the toe-in position of the speakers. Just point them straight out.
  13. ReliaBill Engineer
    I’ve modified the crossover to get rid of the high frequency resonance of the dome, yet still keep the high frequency response.
  14. ReliaBill Engineer
    So, I’ve started testing a new midrange dome for the 1965 AR-2ax pair I have. I have to say, I was underwhelmed at first. This dome sounded “thin”, but very clear. Then I drew out the schematic of what I had, and realized I had to remove the existing crossover’s influence; I had only turned down the mid pot, removing the original mid from the circuit, but NOT the influence of the cap and 16 ohm pot inside the cab! By connecting my circuit at the rear terminals, I was paralleling my circuit with the internal mid circuit. But once I clipped the wire between the pot and 6 uF cap inside the cab, disabling the mid circuit, and listened again, I was truly amazed!! A very airy, smooth, neutral and detailed sound. But because the (super) tweeter and woofer are still in the cabs, playing with my dome mid, there is still that AR sound. Im still making adjustments to the crossover. I’ve added a 20 ohm pot. I made faceplates that match the existing hole and screw locations. In the end it will be a drop-in replacement. But for now, I’m listening to the dome placed on top of the cabs. Once placed into the cabs, I know it will sound a tad different. But not much.
  15. ReliaBill Engineer
    I won’t be using the “approved” midrange replacements. I’ve selected and listened to my choice already. As for crossover, I’ve already designed it, and am waiting for parts. I will assemble it, then listen to it extensively and make any modifications needed. I’m going to leave the existing mid in place, positioning my replacement outside (on top) of the cabinet for comparing. Wire the replacement directly to the external terminals, and turn the pot for the existing mids to zero. This way I can do a very close comparison, A/B them. Ultimately, the new mid and XO will be a drop-in replacement without corrupting the cabinet, nor original XO circuit. It will be for those wanting to upgrade the sound, yet not be irreversible from original drivers or crossover. If later sold, both pairs of drivers can be included with the speaker pair; a choice of performance.
  16. ReliaBill Engineer
    I won’t be using the “approved” midrange replacements. I’ve selected and listened to my choice already. As for crossover, I’ve already designed it, and am waiting for parts. I will assemble it, then listen to it extensively and make any modifications needed. I’m going to leave the existing mid in place, positioning my replacement outside (on top) of the cabinet for comparing. Wire the replacement directly to the external terminals, and turn the pot for the existing mids to zero. This way I can do a very close comparison, A/B them. Ultimately, the new mid and XO will be a drop-in replacement without corrupting the cabinet, nor original XO circuit. It will be for those wanting to upgrade the sound, yet not be irreversible from original drivers or crossover. If later sold, both pairs of drivers can be included with the speaker pair; a choice of performance.
  17. ReliaBill Engineer
    Well RoyC, subjective testimony is all anyone ever has. Even showing frequency sweeps are subjective; they don’t tell anyone how a speaker or driver *sounds*. T/S specs and plots don’t tell anyone how something *sounds* either. You rebuild original drivers, but I have no idea how they *sound*, only what they look like and the price. At least I’ve provided a chance at hearing how something sounds. I’ve tried to be informative. Everything in here re: speakers is subjective. The alternative is to be *definitive*. How do we do that? I’d like to know. How *should* 50-60 year old speakers *sound*? Where is the definitive, non-subjective standard? Can we see it, hear it? Does anyone have a pair of *perfectly* preserved speakers, deemed perfectly preserved by a definitive authority? I know the answer is “no.” My “subjectivity” is no less valid than your “subjectivity”, or anyone else’s “subjectivity”. That’s all anyone has. Measurements don’t tell a person how a speaker or driver *sounds*. They can assist with an intended design, or response. They can serve to stack the deck in one’s favor. That’s about it. Where I work, all manner of measurements are done, models of stresses, pressures, forces and thermals are done, all to make predictions, assess and assign risks. But they in no way guarantee how Artemis will fly until it’s launched.
  18. ReliaBill Engineer
    I have no idea how/why this ended up in tweaks and mods. But ok.
  19. ReliaBill Engineer
    Naive? Detail is the ability to resolve and reproduce complex integrated sine waves, without distorting or homogenizing the waveforms into something barely recognizable and foreign to the original waveform. In the world of phono cartridges, it’s well understood how one cartridge can resolve great detail from the grooves, but a lesser cartridge can’t. Speakers are transducers exactly like phono cartridges, only in reverse. An equalizer only emphasizes (or de-emphasizes) the power response across a relatively wide band, and has nothing to do with a driver’s ability to resolve complex waveforms. It is widely recognized that the dome midrange of the 3a is more expensive and superior to the paper cone midrange of the 2ax. No? But I’m not done. I’m not going to use the Peerless domes, while they do sound good. (I’ll use them in a pair of Wharfdales that need TLC, W70C.) I found a dome that “emulates” the 3a better. It “emulates” the 2ax better. For those with no midranges, or damaged midranges, they might find it useful to read about another’s attempts to try something else. Or even learn what not to do. Nope. I didn’t just “drop” another driver into an empty hole in the baffle. The second set of dome midranges I’m working on are hard domes, not soft silk. The T/S parameters, sensitivity, resonant frequency, useable frequency band, impedance curve, Q (electrical, mechanical, total) are all similar to the AR hard dome mid. It has very smooth response characteristics and great off-axis response. It blends perfectly with the AR woofer and tweeter, in sound and appearance. So no, I’m not just dropping a driver into the hole in the baffle, not any more than using the HiVi unit. But if someone IS going to replace an AR driver, it needs to have complimentary and redeeming qualities. No? And I think everyone knows how to keep original AR drivers in the AR speaker. Basically, you do nothing. Not much of a challenge, really. And keeping (resurrecting?) the AR “sound” is a moving target; what was the sound when the speaker was first manufactured? Who really knows? How does one evaluate that, and conclusively, definitively, *know* and make a comparison? (I have nothing to “protect” here, I’m not in the business of selling my advice or services.) Appearance, yes. That’s a known quantity. Time and environment takes its toll on the appearance and performance of vintage speakers.
  20. ReliaBill Engineer
    Very reliable mid-tweets, for sure. Not much to fail, really. But once I removed one, I was underwhelmed by the quality. I know the 2ax had to meet a price point. The woofer is well made, tweeter the same as the 3, XO nearly the same as the 3, cabinet is well made. So the mid-tweet was a compromise. Keeping the (super)tweeter and woofer, the character of the AR is still there. Using the old Peerless dome mids. I first used these in 1982 and love their neutral, smooth sound and detail. Found a pair on eBay.
  21. ReliaBill Engineer
    Yes I have. A good friend had a pair. Fact is, he has posted in here. Unfortunately he passed away a few months ago. It was my listening to his a couple of years back that got my attention to vintage AR speakers. His had the HiVi tweeter, but his repair shop that installed the mod didn’t do it correctly, so he didn’t get the full benefit.
  22. ReliaBill Engineer
    My wife and I auditioned the new dome midrange driver last night. I won’t go into driver/fit detail here, as it’s not appropriate. I left one speaker as-is, the other with the new midrange. Set my integrated amp to “mono” so I was sending an identical signal to both speakers, side by side. The new dome didn’t change the sound “character”. But it sure did add the detail I was missing! SPL was dead on, and the crossover point was dead on with the original. Pot worked perfectly. Seamless with both the woofer and tweeter. Detail can’t be changed with an EQ; only relative SPLs can be altered. This dome has wide and smooth off-axis dispersion, and resolves massed strings and horns extremely well. The cone mid muffles those very articulate, delicate details. I’ll start a new thread in the mods and tweaks section. Doing a search, I see loads of info on replacing the tweeters in these and in 3/3a with new HiVi units. Seems to be accepted as a non-tweak. I see nothing about replacing these little paper midranges in the 2ax, and 4a/ax. So I think I can add some value to the discussion. In a side by side comparison of the dome to the original paper cone mid, I could hear *why* AR put the fiberglass damping pad over the paper mid. And I can now see/hear why the 3a is heralded for its better mids using the AR dome mid. I will venture that this tweak/mod will bring the 2ax even closer to the 3a.
  23. ReliaBill Engineer
    If speakers can’t resolve differences in cartridges, then just how much “music” are you getting from your speakers? If the AR-2ax speakers present a Shure M44C (1964) the same as a Shure V15V-MR (1983), then there is a tragic loss of detail. Or an Empire 108 (1959) the same as an Empire EDR.9 (1980), there is something very amiss. Music? I can get that over my iPhone.
  24. ReliaBill Engineer
    I’ll make a new post there. But I felt it necessary to bridge this thread to a new one. But i see many mods and tweaks in the AR-3a rebuild section. Certainly not all original.
  25. ReliaBill Engineer
    Well, after months of listening, I’ve decided I’m going to replace the midranges in these. They just don’t produce the level of detail I want. After a long search, I found the midrange drivers I’ve been looking for. They have very similar DC resistance and impedance, and sensitivity to the original paper cone midrange drivers. Also, a very similar frequency response, extending out to 10 kHz from 500 HZ, and flat with very good dispersion, varying only 6 dB at 45 degrees off-axis. So I won’t be changing the crossover, nor pots. They aren’t a drop-in replacement, so I’ll have to modify the faceplate to fit in the existing mount hole in the baffle. Once done, I’ll post results. I’ll document my work. I’ll also make comparison recordings, by doing one speaker at a time. My goal is to make these sound very similar to the early AR-3a’s.
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