To celebrate the holiday season I've prepared a short video. Please note that given the dynamic compression and bandwidth limitations imposed on sound quality by YouTube, I upload videos for the visual aspect rather than their sonic merits.π
So watch how the 720 milliwatts per channel Bonsai Amp is pushed to soft clipping by Tchaikovsky's "Pas de Deux" from "Nutcracker" driving the Altec 753Cs. π
Thank you to all my readers and supporters!
πππWishing everyone happy holidays and a great new year!πππ
It's been over five years since I built this loctal preamp. I moved it recently so that it'd be between my two turntables. In this location, I was surprised by higher-than-usual hum and noise levels emanating from the phono section especially when compared to my RCA octal+ 76 line stage.
Given that it had been playing quietly and flawlessly until it was relocated, I was dumbfounded. Then I noticed that when I put my hand close to either 7F7 tube, the hum and noise got even louder.π€
Before taking the preamp out of the system for a thorough check up on the test bench, I searched for a couple of tube shields from my parts bin.
Before lockdown, Ding promised that he'd introduce me to his friend, Steve Leung, of VAS Audio. He's had his Denon DL103S, Ortofon SL15, Supex SD900, and other classic cartridges re-tipped and repaired by Steve. As the pandemic wound down, I finally got to meet Steve and brought the following MC cartridges for new tips, as well as tonearms for repair at his shop.
My Ortofon SPU GME MKII has had a hard life ever since it was gifted to me by my SETUP buddies in the 90s. It's been on semi-retirement since I acquired an SPU#1s + a late 60s or 70s(?) SPU-G (below) with a low mileage nude mounted conical stylus.
SPU-G
This SPU-G portrays a wider and airier sonic landscape with perhaps a bit more detail compared to my more recent SPU#1s. It also sounds more organic than the GME MKII.
SPU GM(E) MKII - AFTER
I attribute the SPU-G's sonic superiority to the better polished nude mounted conical stylus vs. the bonded conical stylus of the SPU#1s. So I asked Steve to fit his finest nude mounted conical stylus on my GME MKII.
Ortofon SPU GM(E) MKII
Agreeing to my downgrade idea,π Steve may have turned the GME MKII into an SPU-G equivalent of the SPU-A wood. All I know is, it can stand up to my cousin'sSPU Synergy!π
Supex SD900 MKIV
BEFORE
The Koetsu Black and Supex SD900 were my dream cartridges back in the 80s. When I finally found an SD900 I could afford, it sported a ruby cantilever + complex stylus profile upgrade.π Although traces of the classic Supex tonality were still there, it sounded compressed and swamped by dry analytical detail.π
AFTER
I asked Steve to work the same magic on my Supex as he did on Ding's, albeit with a twist. We agreed upon an aluminum cantilever just like the original and I requested for another nude mounted spherical stylus.
SD900 MK IVs (s = spherical)
Steve remarkably transformed the Supex! The harmonic richness and dynamics this classic MC cartridge is known for was restored. To my ears, the SD900's edge over my SPUs and DL103s is its ability to focus and retrieve detail without inducing tinnitus. Because of Steve's phenomenal restomod job, I'm no longer yearning for a Koetsu! π
Being an ardent fan and committed user of the Gray 108viscous damped tonearm and its Japanese clones for monaural hifi applications, I needed to experience a modern iteration of a uni-pivot. This design actually dates back to the late 60s. Scroll down to page 1413 for the review in the Hi-Fi News November 1969 issue. The UA-70 seems to be essentially the same tonearm updated in the 70s with an anti-skate mechanism.
I added the UA-3NL to my collection in early 2018 and paired it with my Thorens TD124 and Sony TTS 2500, respectively. I was going to include this tonearm in my Alfred Bokrand AB309 write-up but one channel dropped out.
When I finally accessed the internal hair-like strands of enameled wire, I realized that repairing it was beyond my DIY abilities.
Similar to the knife-edge bearing'd SME 3012, the Stax presents a mid to back row concert hall perspective, which is an atmospheric experience without any loss of detail. Although I've used it satisfactorily with the SPU#1S, it brings out the best from cartridges that track in the 1.5 > 2.5 gram range. Just like the SME 3012, the UA-3NL may not appeal to listeners who favor a front row seat/kick drum on your chest presentation.
Thanks to Steve's skill and nimble hands, I'm enjoying my UA-3NL again!
So I took out my ancient Cart-Align protractor, did some measurements with my Ortofon SPU#1s cartridge attached and got a pivot to spindle distance of 223mm. I haven't had any problems with cartridges I installed conforming to the SPU's overhang.
It's equipped with a non-standard 4-pin connector in which the negative phase of the right channel is internally grounded. This limits its use to the stock plastic head shell. In an effort to make it compatible with modern metal head shells, I successfully detached the 4 pin connector at the base of the tonearm pillar. It turns out the ground connection was near the head shell collet, which I couldn't remove. Instead of risking damage, I relied on Steve's expertise.
The design may have been inspired by the Ortofon SMG212 and SKG212 with added Japanese innovations. It is quite massive and can easily balance a 30+ gram SPU. So far the lightest cartridge/head shell combo I used successfully was 19.5 grams. Given its high tolerance bearings, it's an ideal partner to the Denon DL103, Ortofon SPU, and similar low compliance cartridges. Consider this as an excellent alternative to the classic Ortofon AS/RM/SK/SMG 212 series tonearms especially if you prefer the svelte proportions of a compact plinth!
iPhone video clips of the MC cartridges and tonearms in action
Classic cameras are regular guests at radio shows and hamfests. However, this is a rare and unusual 35mm rangefinder camera outfit from the 40s - the Kodak Ektra! As the link explains, it was a very sophisticated design for its time but the shutter was very unreliable. Its Contax and Leica contemporaries were much better!
Even if I was a Radio Shack devotee in the early 80s, I didn't pay much attention to this RIAA phono preamp because it didn't have high-end audio pretensions. As the saying goes, ignorance is bliss.π
This unit was first introduced in the 1980 catalog (p. 22) as part number 42-2101 at $19.95, then as part number 42-2109 for $24.95 in 1989, and made its final appearance for $27.95 on page 103 of the 1992 catalog.
Realistic MKVII idler-driven turntable, a future featureπ
With the resurgence of interest in LP playback, it was rediscovered by aficionados and has developed quite a following. No ICs or op-amps are to be found inside. It's a simple discrete circuit, which minimizes signal processing.
!!!WARNING!!!
The voltages in this circuit are potentially lethal! Proceed at your own risk!
The circuit is a basic two stage cascade + a negative feedback RIAA EQ looped from the output back to the input. It is very similar in topology to its tube forebears - the Shure M65 and the phono section of the Dyna PAS.
Typically, I don’t subscribe to a wholesale approach of replacing caps but this is a very simple circuit that was built at a certain price point. Since I had some decent quality parts surplus from my CD player and DAC modification projects, I replaced the electrolytic capacitors in the signal path with film type WIMAs and increased the filter capacitance in the power supply section.
In stock form, I was already impressed by this preamp's listenability when passing through my loctal tube line stage. The parts upgrade tidied up the sound further, but it wasn’t a magical transformation.
In terms of midrange presence and transparency, low level detail, micro and macro dynamics, this preamp isn't the equal of the Shure M65 or a refreshed stock Dyna PAS phono section. Its main advantage over its vacuum tube forebears is low output impedance. This could plug into the 10k input Z of the Nobsound NS02g/JLH 1969 with no loss of frequency extremes. I won't recommend that with the M65 or PAS. There's also a slight graininess in the midrange that wasn't ameliorated by parts upgrades. That said, I don't know if one can find a "plug 'n play" phono preamp in the $100 range (or possibly more?), which will provide as much musical pleasure!
Ever since I discovered the Shield MO19 (aka Neat P58H) and Realistic MkVII at the turn of the new millennium, I've become fascinated by, and in the process have collected a few Japanese idler-driven turntables. To my ears, none of them measure up to the Garrard 301, 401 or Thorens TD124. However, the models I'll be covering in this series, IMHO, offer great musical value for money when properly sorted.
For this initial installment, I'm featuring the Pioneer PL6U, which I used as an interim turntable when I returned to the US in 2016. It's the little brother of the Pioneer PL7, which was built to much higher specifications.
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