Eminent Technology ET-2 Tonearm Owners

Chris

So just a question.
Bass waves are slower than all the others. So why do people put subs X feet behind their mid and tweeter drivers ? Just asking.

If I was you Harry I would be very tempted just "temporarily", to set up in near field for one hour - just to hear what was possible with one sub.

I’m not exactly shure what this would mean? More upfront placement = faster bass?
Placement is a question of "allowable" phase angles between drivers caused by offset drivers (specially in distance to the listener). As long as this offset phase angle is not far off, there is no "real" problem.
Bass waves travel at the same speed as any acoustic wave in air, but have longer wavelengths, so offset distances in the low bass can be considerable without being audible. Usually it’s said to be desirable to be below 90 degree - I’d keep it lower, to be on the safe side in the cutoff region where the subwoofer is still emitting considerable upper bass levels.
At 40 Hertz xo this would still be 67cm for a quite tight max. 30 degree difference. This results in an allowable 120 degree two octaves above, at 160Hz, at eg. -24dB (for 12 dB/oct.)
But I agree, that close-field placement is the preferable "error", because a) the excursion / level of the subwoofer can be considerably lower, b) the decrease of room reverberation level relative to the direct sound level should reduce audible room resonances & bass colorations = c) the modification of the subs frequency response by room resonances drops an order of magnitude.
But... it works only if there is no spurious midrange energy exiting reflex tubes or coming from the driver. Still - the lower sub levels reduce distortion and "box talk" & "cone cry", both help.

Chris & Everyone,
Will respond to Chris and his subwoofer discussion later.  Right now I have a crisis.  While listening tonight I was hearing dreaded rumble in quiet passages.  Upon investigation I discovered the shaft on my stand alone motor assembly for the VPI HW-19 was so loose it was actually wobbling.  And we all know what a warbling shaft can cause - Rumble!  

My SAMA is the original in the round silver base not the later one with beveled corners.   Been searching Internet and all places that had it appear out of stock.  I don't think VPI makes this SAMA any more.  Does anyone know if the motor assembly can be removed from the base and replaced and, if so where the replacement motor can be purchased?  Any suggestions will be appreciated.
Thanks,
Harry

P.S.  Tweaking is fun.  Breakdowns are not.😰

Harry so your motor looks like this ?

See this thread on the VPI forum.

specifically one poster says.

"First, tighten the pulley on the SAMA (there should be a grub set screw on the pulley collar). This should stop the wobble."

Not saying this is your problem but check.

and other than that, if the shaft is loose but still works and the wobbling is not caused by the SAMA feet; then I would be tempted, to remove the top screws and have a look inside. If the shaft is on a type of frame holding it up, one of the frame feet or frame feet washer if one even exists may need replacing.

Just giving ideas. long time since I had the hw19 mk4.

Chris

Chris, I wish I could give you a more interesting 😉 description of how I remove tonearm cartridge leads from a cartridge, but my method is exactly like yours. Only thing I would add is that the tiniest amount of Deoxit helps keep the connection lubed and easier to separate while presumably also helping conductivity. Your use of a toothpick is also my method of expanding clips that are too tight due to overcrimping. As you know, when crimping the clips in order to make the connection tighter it is all to easy to crimp it in a way that the clip loses round; this would most likely decrease the number of contact points between the clip and cartridge prong. I took a small needle nose pliers with serrated "teeth" and by using a small thin round hobby file I made the space between the "teeth" and on both sides just wide and deep enough to cradle the cartridge clip; this allows crimping with equal pressure along the entire length of the clip without deforming it; and I do this with the toothpick in the clip to help keep round and to prevent overcrimping. Re subwoofers:

In my experience, you are exactly correct re near field placement. My pair of REL’s sit on either side of my two-person listening couch. I set the xover point as low as possible; usually at 28hz with occasional adjustments of a couple of hz one way or the other depending on the recording. I find that anything much higher than that thickens the sound in the midrange unnaturally and what I am looking for, more than anything, is not necessarily more obvious bass weight, but the concert hall (and studio) ambient information that is found in that frequency range. I also find that the midrange, independent of the presence of obvious bass information, takes on added purity and density when the system can reproduce the lowest frequencies. A controversial topic and not entirely understood (certainly not by me), but just as there exists the overtone series in music, we have undertones or subharmonic series that factors into all this. For instance, a recording of a woodwind choir playing in a range well above a subwoofer’s xover point will sound noticeably fuller and with more tonal density (as in live music) with the subwoofer on than with it off; importantly, and as Pegasus points out, eventhough there is no spurious midrange information being reproduced by the subwoofer. Re inverting phase setting: I think whistling 😚. One can whistle while blowing air out or by sucking air in. To me, the correct phase setting sounds like the bass is being projected out (as it should be) as opposed to sounding like it is being sucked in. The latter, as well as generally sounding weaker in volume, detracts from the contribution of the bass instruments in musical terms. I like your hand on the woofer cabinet method. Btw, while I generally agree that directionality is not a major issue with subwoofers, before I bought a second REL,  I found that with a single sub "up-front" with the main speakers sometimes center images would subtly "lean" in the direction of where the sub was placed (if to one side or the other); again, whether there was obvious bass information or not. Regards.

Hello Chris,
Good audiophile day here in the Carolinas. Crisis over.  I tore down the VPI to more closely inspect the shaft and pulley on the SAMA.  My SAMA is a very early version which included a small flywheel.  It is like a very fat stainless steel washer that slides down over the pulley and rests on a flange at the bottom of the pulley, just above the motor housing. It is not attached to anything but just sits on the flange.  I noticed that the flywheel was wobbling far more than the pulley/shaft.  In discussions with a former dealer friend of mine in Florida he advised that the flywheel only came with very early versions of the SAMA and VPI had abandoned it because they found it more detrimental than helpful.

So.......I reassembled the table and tried it without the flywheel.  Voila, rumble and speaker pumping all but gone.   It's not 100% but pretty close.  I'll need a new motor someday but it is certainly not critical.  Incidentally, I had the same thought regarding a loose set screw on the pulley.  That is why I tore down the table.  Unfortunately, this version of SAMA has no pulley set screw but is evidently pressure fitted over the motor shaft.

Chapter 2:. Santa Clause arrived today with my magnesium arm wand. I installed it and redid setup.  I'm only using the one big weight in addition to the one to which the other weights attach.  Initially one weight was not enough to get proper tracking force even at the very end of the plank.  Rather than add weight I turned the weight bracket around so the weight barrack screw points out instead of in.  Unfortunately, I installed the new wand right after solving the rumble problem so I'm not sure which improvements are attributable to which tweak but, midrange seems a little warmer, bass tighter, separate instruments seem better defined and upper end smother but no less extended.  I don't have 20 foot wide pianos or drummers with a 15 foot wingspan. Finally, the soundstage seems a little deeper.

Next time wife is away for a few hours I'm going to try the near field sub placement.  More on subs later.
Cheers,
Harry