Since Denon recommends a 1000 ohm load for flattest response, I tried soldering a 1k ohm resistor in parallel with the 47k input (47,000 x 1000/47000 + 1000 = 980 ohms) of my variable EQ phono preamp. Unfortunately, the sound became even more glacial.
I could have been basking in warmth by now (without losing stereo LP compatibility) if I saved up for an Ortofon SPU mono but the DL102 body fits a Gray Research or clone tonearm slide perfectly. Besides, I would rather add more stereo SPUs to my cache.😉
Since I've been using 1:1 line transformers as digital sound processing devices at the output of my CD players for ages, I decided to try the same trick by wiring the Altec 15356 and UTC A20 with a mild step up - 150:600 and 125:500, respectively. Even if both primaries reflected significantly less than Denon's recommended 1000 ohms, what I heard encouraged me to continue to experiment.
Although I'm not anal retentive about impedance matching, I was curious too see if the sound would improve by using transformers that reflect at least twice the 240 ohm internal impedance of the Denon DL102. I managed to procure the three transformers above: to the left is allegedly a Tamura 600:3k, then I tapped the McMartin MT-4's 10k:60k winding, and at the center is a permalloy 10k:40k, which sells for about $50/shipped from Chinese sellers on AliExpress and eBay.
In the context of my mono hifi set up, the McMartin MT-4 was a bit too warm for my taste. However, even if I upload videos merely for the visual spectacle, the permalloy (above) and Tamura (below) transformers are lush enough for me.😉
In the early 2000s, the swinging tonearm mount of the Shield MO-19 caught my attention because it looked like the perfect partner for my Velvet Touchviscous damped tonearm. It turned out that this Japanese 4-speed idler-driven turntable is actually a rebadged NEAT P58H.
I got this NEAT P58H + Tokyo Sound ST900 tonearm when Tish and I returned to the States in 2016. It wasn't as well kept as the MO-19 and required a bit more fettling.
The turntable is built on a heavy duty cast chassis with a 1.5 kg cast aluminum platter. Aside from a few discussions in audio forums, the only literature I've found about this particular model is the 1960 NEAT catalog available for download at vinylengine.com.
Everything I've done to my NEAT P58H and Shield MO-19 is documented below.
Idler wheel + idler arm
The rubber on this NEAT P58H idler wheel was in good condition except for a pinch, which couldn't be removed by minor grinding. So I sent it to Terry E. Witt for new rubber.
The idler wheel arm action should be snappy. If it isn't, back off the nut a bit and/or add a bit of light oil to the sliding surfaces.
A good balance between speed accuracy, torque, and low noise can be achieved by adjusting the idler wheel contact pressure to the inner rim of the platter.
Unplug the turntable from the AC source and manually spin the platter CW or CCW. The platter should gently stop when the speed control knob is turned to any of the speed settings as the idler wheel engages the inner rim of the platter. If the platter stops abruptly or doesn't stop at all, go back to the preceding procedure and adjust the idler wheel position on the idler arm accordingly.
60 Hz pulley dimensions +
red arrow indicates the pulley's set screw for height adjustment
While the turntable is disconnected from the AC source and the speed selector set at 33 rpm, I set a 1-1.5mm clearance so that the idler wheel doesn't touch the shoulder of the 45 rpm step.
Speed Selector Mechanism
With the speed selector at the 78 rpm setting, make sure there's no clearance between the tip of the set screw and the piston which raises and lowers the idler wheel arm mechanism.
Before we move on, how about a track from Style Council?
Motor
The turntable is powered by a fairly substantial 4-pole hysteresis synchronous motor.
Through the years I've gotten requests for a schematic because some of these turntables were hastily pulled out of installations by flippers for quick bucks on eBay.
Spring suspended motor = less vibration
Top view of the motor + sub-chassis
The deteriorated bottom rubber mounts (red arrows) can be replaced with rubber grommets.
To remove the motor, unsolder the motor wires from their respective connections. Use my hand drawn schematic above as a guide. Then, remove the four nuts marked with blue arrows.
Before pulling out the motor entirely, I marked its orientation (black arrows) in the sub-chassis for easier reassembly.
To disassemble the motor, remove the four nuts marked by the yellow arrows.
Motor parts ID
The top and bottom shells house the sintered bearing well and are almost identical in construction except for an exit hole on top for the motor spindle. I marked the partially visible sintered bearings (or bushings) with blue arrows. To access the bearings for cleaning, remove the spring clips marked with green arrows.
As shown in the picture above, the bottom shell has a thrust pad. I clean sintered bearings by soaking them in solvent, either lighter fluid (Naphtha) or isopropyl (91% or greater) alcohol (IPA) overnight. For lubrication, I use blue 3-In-One SAE 20 motor oil.
The parts inside the bearing well are numbered in sequence for reassembly.
To access the motor bearing, remove the bottom cover, which is held by three small screws + lock washers. Be careful not to lose the tiny 3mm ball bearing. Clean all the components with either Naphtha or IPA. The numbers indicate the sequence for reassembly.
The motor should now be whisper quiet in operation.
Just like the Shield MO-19, I also found old grease at the end of the threaded bottom cap of the main bearing of the P58H. The lack of an oil seal in the threaded bottom cap further confirms that this is a grease bearing design.
These are the main bearing components after cleaning (soaked in solvent overnight). They're ready for fresh grease and reassembly. I used Phil Wood grease left over from my Raleigh 20 restomod folding bike project.
The Garrard 301 grease bearing makes the NEAT P58H bearing look diminutive.
CODA
Although innovative in its own right, the various pictures show that the mechanical design and manufacturing quality of the NEAT P58H/Shield MO-19 isn't quite as sophisticated as the illustrious Garrard 301, 401, or Thorens TD124. I never envisioned it to equal those revered models in terms of performance. However, IMHO and experience, a reconditioned NEAT P58H is a worthy alternative to a restored Lenco or Rek O Kut.
I found this interesting phono cartridge on eBay for under $30 shipped.
It was advertised as a vintage Sony magnetic cartridge. After clicking Buy It Now, I asked the seller for more details. Sadly, my inquiry fell on deaf ears...
The stylus assembly is very similar to that from the AT-5.
But the body shape is somewhere between an AT-1 and AT-3S.
After getting a feel of cantilever compliance and seeing the bonded conical stylus under a USB microscope, it felt safe to set VTF at 3 grams. The stylus has yet to skip a track!
Although not quite as dynamic, the tonal balance of this vintage cartridge is reminiscent of my all-time favorite Shure M3D. I’ve listened to it extensively mounted on the Tokyo Sound ST900, Fidelity Research FR54, and Bokrand AS309. I would've recommended this cartridge highly as a nice budget alternative to the M3D or M7D IF the eBay seller didn't go AWOL.
A video of the vintage cartridge tracing an Abbey Lincoln track.
While debating whether it was still worthwhile blogging about a mysterious vintage cartridge that can't be found anywhere, an elongated box arrived at our doorstep.
Inside the ginormous box was a tiny little box. Apparently someone in the packing department couldn’t care less about conservation.
It turned out to be my order for a phono cartridge, which showed up on my feed while I was searching for Blue Note Jazz LPs on Amazon. No literature was provided aside from the stickers on the outer box and plastic protective case. The cartridge isn’t even identified with a trademark or model number. Henceforth, this will be referred to as the Amazon cartridge and the other, the vintage cartridge.
A phono cartridge for under $18 shipped and taxed is like an early 80s dèjà vu when I could walk into Leonard Radio on Sixth Ave. NYC, listen and browse to my heart's delight, and walk out with a $15 Grado GTE+1.
The plastic body is quite robust weighing about 6.5 grams. Instead of traditional mounting holes, the body is threaded. Over tightening the two Allen head mounting screws can result in stripped threads.
The google translate camera app on my iPhone gave the above info. I suppose 2.2 grams acupressure = Vertical Tracking Force, since it uses a stylus not an acupuncture needle. OTOH, the printed 5 gram weight doesn't match my digital scale's reading.
I haven’t mastered the use of my USB microscope and this is the best stylus image I managed to capture. It looks like a nude mounted rock with traces of facets. Could it be an elliptical or a not too highly polished conical? I'm not an experienced stylus peeper, so please let me know what you think.
I mounted the cartridge on a generic Technics-style head shell and set the acupressure to 2.2 grams on my Bokrand AS309. After a couple of tracks I heard sibilance. Increasing the VTF to 3 grams fixed the problem. IMHO, 2.2 grams is too optimistic!
The metal shield of the Amazon cartridge looked similar to the entry-level Audio Technica AT3600L. So I took it out and, as expected, it sounded comparatively dark and veiled. Switching to the Pfanstiehl conical stylus opened up the sound a bit. However, the full bodied tonality of the Amazon cartridge wasn't at all apparent leading me to believe that the two cartridges don't share the same motor.
The Amazon cartridge is a very exciting performer! Macro and micro dynamics are more nuanced, I hear more air on the top end while midrange vitality and low frequency extension are at par with the vintage cartridge. If I'm forced to split hairs, I'd say the vintage cartridge is a tad more refined compared to this Amazon special.
Same Abbey Lincoln track traced by the Amazon cartridge
As I was about to link to the item on Amazon, my original source was showing as currently unavailable. But a bit of searching yielded a blue/gray variant as pictured above that's listing from $19.46 to $23.99. Happy shopping!
As featured in the two videos, most of my listening and testing were done via my near field hifi. But I also cross referenced the cartridges fitted to the Bokrand AB309 + Garrard 401 downstream to the Altec 753Cs in the main system. Neither cartridge unseated the Shure M3D as my favorite magnetic cartridge but both provide a level musical satisfaction unimaginable at this price point!
Addendum
More stylus pictures
Click on the images to enlarge
I forgot to mention that when I did the AT3600L vs. $18 Amazon cartridge comparison, I was reminded of a Pickering V-15 vs. XV-15 match. Could there be a moving iron motor inside this Amazon cartridge?
Suffice it to say, I've been enjoying my $18 version so much such that I'm not in a hurry to re-mount the Shure M3D.😊
Here's another video of the $18 Amazon cartridge, this time mounted on a Fidelity Research FR54 tonearm tracing a track from Naked Eyes in honor of Burt Bacharach (1928-2023).
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