Turntables and Pickups and Preamps, oh my!

So…
I’m not one of those obsessive audiophiles that insists vinyl is superior to both sex and all other audio mediums… although a good LP recording can be stunningly engaging.
So, why then LP’s and such?
I appreciate retro audio equipment, times past, and music that isn’t available any other way. And it’s cool to get 60 year old audio technology working again!

In the mid 70’s, I was a budding teenage audiophile, but had no money. I got a job mixing and hauling cement for a month, no mean feat for a 110 lb weakling. I saved almost every dollar I earned from that job, then used it all to buy my first new turntable; a spiffy BIC 960 with a Micro Acoustics 2002e cartridge.
This was pretty much audio nirvana for me, and a huge step up from the old garage sale Garrard clunker I was using.
The BIC served me well for years, until it got crushed in an earthquake in the 80’s. The turntable base, platter, and tonearm was mangled and I had to scrap it, but I kept the cartridge and my records, thinking someday maybe I’d get a turntable again…
In the meantime, I moved to that new digital thing, CD’s. See D5 CD player.
.
But something was missing…
There’s a set of sensations to playing a record, the smell of vinyl and cardboard, the feel and look of the album cover, the ritual of cleaning and cuing the record up that is really engaging, like opening a book and sitting down to read. So I decided it was time, and…

A – Technics SL-1210 MK5 (circa 1972-2010) – “My Last TT”

About twenty-five years later (2007-ish) it looked like turntable production would be ceasing soon in favor of digital. At that time, I assumed this would be the last turntable I’d ever need, so I wanted one that would be low maintenance and extremely durable. I selected the Technics 1210 MK5, purchased it from kabusa and had it “hot-rodded” with their mods for 78 RPM, a record clamp, and their precision prep. It’s still my primary turntable, rugged, reliable, quiet, and has easily swappable head shells, which was a key feature for me to also play 78’s and battered LP’s.

Specs:
Rumble: –78 dB (IEC 98A Weighted), –56 dB (IEC 98A Unweighted)
Wow and flutter: 0.01 % WRMS\0.025 % WRMS (JIS C5521) ±0.035 % peak (IEC 98A Weighted)

For good condition LP’s, I use a variety of pickups on this unit, depending on record condition, record type, or just sheer whimsy.
1 – Micro Acoustics 2002e with a retipped micro ridge stylus, tracking at 1.1 grams
2 – Shure V15 /// w Jico VN35SAS stylus – tracking at 1.25 grams
3 – Audio Technica AT440MLa w purple grip stylus – tracking at 1.4 grams

For other records:
4 – For beat up LP’s and other microgrooves – Low cost AT cartridge and stylus
5 – For 45’s – Shure M97xE w blue grip N97xE stylus with the damper brush – tracking at 1.25 grams, used for good condition 45’s
6 – For 78’s – Shure M70BX w green grip N78S spherical stylus – tracking at 2 grams
Note: 78’s need a large tip stylus and a special phono preamp with variable turnover/rolloff (ie EQ) settings. If you’re using a 78 needle in a stereo pickup (like me), you also need a sum to mono circuit. And a pop/tick remover can be very useful. See below in the preamp section for more on all this.

B – BIC 981 (circa 1976-1978) –
Vintage TT Recreation project

In July of 2020 I was cleaning out my turntable accessories box and came across my forty-plus-year old Micro Acoustics 2002e cartridge, two worn styli, and the original BIC alignment jig & 45 single play adapter. Hmmm… I liked that turntable and its sound. For fun, I decided to recreate that system for nostalgia’s sake.

Specs:
Rumble, -65dB (DIN)
Wow/flutter, < 0.05%

Perusing eBay, I immediately tumbled into a BIC 981 with all the key bits intact… minus the alignment jig. The 981 was the upscale version of the 960 I had, so this is fate at work, methinks. This unit has the head shell, the LP single play spindle, and even the dust cover, all in good shape.
The turntable should arrive shortly, hopefully it survives transit.

For cartridges, I have a rare vintage Micro Acoustics 2002e w two stylus’s, and a vintage Shure V15 /// with the red 35-SE stylus pull. These two are still both highly regarded today, and there are still a few meticulous jeweler types that patiently repair and retip these 40+ yr old cartridges and styli. So off they went for refurbing and retipping, courtesy of Andy at Needle Clinic: https://phonocartridgeretipping.com/
(He did a fine job with the refurbing, see below. I went with the microridge upgrade, well worth it!)

The Rebuild:

UPDATE 1: As insurance, I wound up getting a spare “working 981” turntable. If things went well, I would have two working units; if things did not go well I could raid one for parts.
UPDATE 2: That turned out to be very wise, as one of the 981’s was crushed and badly damaged in transit. I need to look at it more closely, but it’s almost certainly a parts unit now. 🙁

BIC 981 TT damage – tonearm
BIC 981 TT damage – base

The bent tonearm is a real bummer, these things are quite delicate.
Also very bad is the platter is crushed into the base and doesn’t turn. It might have a unfixable bent spindle. Rats again. The seller kindly reduced the price to what a parts unit would be, so there’s that.
And the precious 2nd gen head shell is in good shape, the base can be re-glued, and the dust cover is usable with no major cracks. Oh, and the drive assy and electronics still looks good too.

However, the other turntable arrived in really good shape (most excellent packaging), and a cursory examination shows it’s basically working. A forty year old turntable will undoubtedly require some refurbishing so that’s next on the docket for this unit, which I’ve now dubbed “Prime”.

UPDATE 3: 2020.07.16
Prime’s base needed cleaning and some orange oil, and the dust cover buffed out fairly well with plastic restorer. A few under chassis parts parts needed lubrication, and viola! things were more or less working!
I noticed the special tray “hinge” the dust cover rests on was broken/missing, so parts unit made it’s first donation to prime. Prime now looks like:

BIC 981 Turntable
BIC 981 prime TT

Next up, investigating the motor speed control board and it’s poorly documented adjustment pots.
The motor driver board (an op amp oscillator wien bridge design with an incandescent bulb for the AGC servo) deserves it’s own doc, which is in process. (insert link here when done)
Once properly adjusted, this design outputs a stable, low THD sine wave to the motor and provides a quiet and stable ride. along with a bit of pitch control.

UPDATE 4: 2020.07.21
The rebuilt cartridges have returned!
I promptly installed the Shure V15 /// in the special BIC headshell, carefully aligned it, and put it on the tonearm. After setting tracking force and such, played an old Michael Franks jazz LP. Wow, sounds great!

The micro ridge profile stylus apparently rides in a different spot on the LP groove than the elliptical profile stylus of old, as the LP was quieter and had a lot more top end air than I remember. Most encouraging.

BIC 981 playing an LP
Mostly restored BIC 981 playing an LP with a restored Shure V15 /// SE cartridge/stylus

Checking the work

The alignment jigs, precision scale, and test record have all arrived, so I can do a proper setup and test soon.

C – Dual 1242 (1978-1979) – prop unit

Around June of 2012, I picked up this turntable to use as a photo prop for a 70’s themed photo shoot. However, it was in excellent condition and with very little work it actually ran as well as it looked. It’s a nice belt drive with some automatic features. For now, it remains a prop though, as I already have two turntables in use.

Specs:
Rumble, -42 dB unweighted, -63 dB weighted (DIN 45 500)
Wow/flutter, 0.09% (DIN 45 507)

T.T. D – JVC L-F210/L

In 2022, this TT jumped into my lap, along with a pile of other JVC stuff. I think it has an Ortofon F/FC cart?

TT Specs:
Rumble: not spec’d
Wow/flutter, 0.03% (WRMS) 0.055 (DIN)

Got it for free, so….

About phono preamps: Gain and EQ

Connecting a turntable to your system also involves a special high gain “phono preamp” with some EQ….and now things get really complicated.

Gain:
If you have a Moving Magnet (ie MM) cartridge, then you need around 35-40 dB of gain. If you have a less common (and usually more expensive) Moving Coil (ie MC) cartridge you need a lot more gain, some 50-60dB is called for.
The phono preamps for these two categories of cartridges are usually called (you guessed it) MM or MC phono preamps.

EQ:
Almost all post acoustic era “electric records” were created with a frequency equalization schema that was designed to help compensate for physical record limitations. This EQ is usually a bass cut and a treble boost applied at master cutting time.
To play back the record with the correct spectral balance, you merely reverse these compensations and get back to the original source frequency response.
IOW, you apply bass boost “turnover” and treble cut “rolloff”) at playback.

Applying the proper playback EQ is key to getting the best sound from records.
If you want to play LP’s and 45s from about the mid 50’s on, then all you need is a phono preamp with the now standardized RIAA playback EQ curve, which is:
-> 6dB/octave boost at 500Hz, or a +12 dB boost at 100Hz. This is the “turnover”, specified relative to 1KHz.
-> 6dB/octave cut at 2122Hz, or a -13.7 dB cut at 10KHz. This is the “rolloff”, specified relative to 1KHz. (I won’t wade into the IEC vs RIAA debate here, look it up.)

Notice the flattening at 50 Hz. This diminishes mechanical noise and resonance issues.

But if you want to play earlier pre-standard media (most notably 78’s), read on!

Special notes for playing 78’s
Prior to microgroove LP’s and 45’s were 10″ shellac 78’s. These pre mid-50’s recordings were all over the park in terms of playback EQ, actual speed, and groove width.
– Many were cut with no treble boost, so the later “RIAA standard” roll-off makes them very murky sounding indeed.
– The bass turnover was selected per company, so it varied a lot. Fortunately, a 6dB /octave boost starting at 300 Hz is a reasonable close compromise for most electrically recorded discs.
– This was before stereo, so you need either a mono cartridge or sum the two channels together.
– Speeds varied, from low 70’s to over 84 RPM, 78 RPM was a later “nominal” speed.
– Lastly, a wider grove means a wider stylus is needed to avoid excessive noise. 78’s need a larger stylus tip than the micro-groove sized ones for LP’s and 45’s, again there was a broad range. I use a Shure M70BX cartridge w green grip N78S 2.5 mil spherical stylus, tracking at 2 grams. again, this compromise that works well enough for me.

EQ:
About: http://pspatialaudio.com/record_characters.htm
A handy chart – http://www.shellac.org/wams/wequal.html
Another good reference: https://midimagic.sgc-hosting.com/mixphono.htm

Speed
https://charm.rhul.ac.uk/history/p20_4_3.html
Groove widths and Stylus recommendations

Other resources:
78rpmrecord.com
78’s digitized by George Blood: https://archive.org/details/georgeblood

Other interesting links:
The science behind step up transformers for MC
http://www.rothwellaudioproducts.co.uk/html/mc_step-up_transformers_explai.html


Last Updated on 2024-01-09 by Daev Roehr