'70s Direct Drive Turntables (and Tonearms)

This is a follow up on the road less travelled article. In 2017, I went on a quest for direct drive turntables that I could acquire for under $250. For the past year I've been tinkering and listening to these four 70s era direct drive turntables to find out whether a direct drive turntable has a place in my ever-growing collection of audio equipment.

Each unit has its own unique approach to direct drive turntable design and was available either as an integrated unit (with tonearm) or as a plain motor unit. The Denon DP1250,  Kenwood KD500 and JVC QL5 are mid-priced models from the late 70s, while the Sony TTS2500 was a first generation early 70s top of the line direct drive unit designed to compete with the original Technics SP10, which, unfortunately, was not within my budget. 😞

Turntables

JVC QL5

JVC introduced the world's first quartz locked turntable in 1974. The QL5 employs quartz locked circuitry to control its 12 pole 24 slot DC type motor. Its jet black plinth is made out of heavy particle board. The motor unit was also sold sans tonearm as the QL50.

Kenwood KD500

Instead of the complex electronics found in the Denon, JVC and Sony, the KD500 uses a relatively simple servo circuit referenced to a frequency generator modulating an 8 pole 24 slot brushless DC motor. This turntable developed a following in the late 70s due to the use of a highly inert and heavy synthetic marble plinth.

 This particular unit was loaned to me by my buddy Ding. He's had it stored for many years. It ran way too fast at first turn on so I replaced these four bulging capacitors immediately.

Denon DP1250

Unlike the two preceding turntables, the DP1250 uses an AC motor which minimizes cogging, according to period Denon sales literature. The motor is governed by a unique tape head inspired speed regulating system. The plinth is a substantial plywood/particle board laminate similar in mass to the JVC.

Sony TTS2500

The Sony TTS2500 is the motor unit of the worldwide bound Sony PS-2250/2251. Just like the Denon, it also uses an AC motor regulated by a servo circuit that is claimed to be practically cog-less in operation. This JDM (Japanese Domestic Market) model requires a 100V step down transformer. The half-finished laminated plywood plinth was DIY'ed by yours truly.😎

Tonearms

In a typical audiophile shootout these turntables would have been fitted with the same tonearm/cartridge combination and plinth. But this was not practical since I wanted to test under real world conditions. So to satisfy JE Labs' retro-centric streak,😉 for the Denon and Sony, I chose period correct gimbal bearing type tonearms that are known to perform on a similar musical level as those supplied with the QL5 and KD550.

JVC QL5 Tonearm

The QL5 is equipped with a tonearm that looks like an economy version of their well regarded UA-5045. With an effective length of 245mm, it is a bit longer than the three 237mm tonearms below.

Kenwood KD550 Tonearm

Ding had a Grace 707 installed before moth-balling this KD500. For some reason that tonearm went AWOL. Fortunately I had the original tonearm supplied with the KD550 in my stash. There are claims that this may have been OEM'd either by Acos or Micro-Seiki?

Rega R200

It would've been nice if I had something along the lines of a Denon DA305 to fit on the DP1250. However, the Acos OEM'd Rega R200 I installed is also a well respected 70s classic. 

Grace 540L

I've always had a soft spot for Grace/Shinagawa tonearms ever since the Grace 707 opened my ears that fine quality tonearm design produces nice sounds. This Grace G540L has similar mass to the other three above. The lack of a cuing device and anti-skate betrays its pro-application heritage. It is the oldest of the bunch making it the perfect partner for the TTS2500.

Cartridge

Denon DL103R

 For critical listening I relied on a Denon DL103R mounted on a Sumiko HS-12 head-shell. But this didn't prevent me from mounting a variety of cartridges in my stash ranging from the cheap 'n cheerful AT 3600L to an Ortofon SPU.

Time travel to the 70s

 Without hesitation, I would choose any of these turntables over the 3-point suspension belt drive turntable I used and tweaked to the max in the 80s. The direct drive system has the sure-footed speed stability which eventually lured me to the TD124 in the late 80s. I should've jumped at bargain priced top of the line direct drives to play with in the 90s...alas, hindsight is 20/20.

Since direct drive solved the ills of wow and flutter, and noise which plagued the belt and idler drive system respectively, there should be minimal difference in the way any direct drive motor unit should sound, right? Not quite...

Denon AC motor (top)
Kenwood DC motor (bottom)

My most surprising discovery after living with all these turntables this past year was the difference in sound between the motors that power them. The DC-motor-powered JVC and Kenwood consistently sounded analytical, cold and forward, akin to a digital source, while the AC-propelled Denon and Sony were characteristically more laid back and warm, just like what I associate with analog sound.

 However, to put things in perspective, the Sony still outperformed the other three direct drives in key musical aspects. In particular, there is a "hardness" and loss of composure in complex musical passages that prevailed on the three units with the Sony exhibiting only the very least amount.

Sony TTS2500 + Stax UA-3NL

Still, the TTS2500 could not eclipse the performance of the 301 or the TD124s. But it is the only direct drive in this group to come close in mimicking the stately authority of the esteemed idler driven classics. 

For this achievement, I crowned the Sony with a 12" Stax UA-3NL tonearm.🍻

November 2018 Hifi Show

To all readers based in Manila, please mark your calendars.

Don't miss a guaranteed good time. 👍👍👍

Here's a preview of what I will miss. 😢

G.I.P. Laboratory + Harana Audio Collaboration

Joey of Harana Audio and Shinichi Suzuki of G.I.P. Laboratory

GIP 597A

GIP 555

GIP 815 in Harana Audio V-Vent cabinets

Harana Audio Workshop

Suzuki-san inspecting the electronics - Wavelength Audio SE45 with Magnequest Cobalt OPTs driving the horns and SE300B with Tamura Permalloy OPTs driving the bass, signal source = DEQX HPD5

Suzuki-san is listening

Approved👍👍👌👌

Time for lunch!

Oh wait a moment...

let's have some Beethoven Moonlight Sonata as an appetizer 😁

Visit GIP Labs in room 646 and Harana/GIP next door, 647. 

Cheers to Suzuki-san and Joey.🍻

Kutztown Radio Show September 21-22, 2018

All pictures were taken with a Fuji X-E1 camera + Canon 28mm f3.5 LTM lens.

I wasn't able to attend as many hamfests/radio shows this past summer. So I made sure I went to Kutztown.  

This speaker caught my attention as something I've encountered in a vintage magazine in the past. Since there was no one manning the booth, I went on...

A pair of University Lowboys + an EV Aristocrat

Nice Gates CB77, but I couldn't afford it 😞

Belt-driven Rek-O-Kut

Scott 299, LT110B FM tuner, Fisher KX100, etc.

Fisher PP EL84 mono block

My bud Larry always has a live demo set-up.

Sonographe SD-1: mid-80s Philips 14-bit oversampling chassis with twin TDA1540 DACs, audio section tweaked by conrad-johnson, nice piece but check out that asking price 😲

Tubes galore!

I scored a TDA1543 equipped Magnavox CD player from this booth. 

Lots of 70s-80s Hi-Fi equipment 

Used CD prices are at an all-time low 😃

The speaker I spotted earlier kept haunting me. I just had to give it a new home. My gut feel was right - it's a Stewart Hegeman-designed omni-directional speaker. 😎

Noguchi Transformer Co. Ltd, Closing

Noguchi Transformer Co. Ltd announced that they are closing on September 29, 2018.😞😞😞

Azzolina Audio KS12024

Western Electric KS12024

Western Electric KS12024
Note: ~ 140° throat bend

The Western Electric KS12024 is a 2-piece cast aluminum 4-cell sectoral high frequency (800-1000Hz cut-off) horn with a 50°H x 40°V dispersion pattern. It was implemented in the Western Electric L-8  and L-9 speaker systems.

Western Electric L-8
from the Silbatone Collection

Western Electric L-8  = 1 x WE754A + 1 x KS12024 + 1 x WE713B (phenolic diaphragm)

Western Electric L-9

Western Electric L-9 = 2 x WE754A + 2 x KS12024 + 2 x WE713B

Western Electric L9
(Note: 2 x WE713B)

Images were taken from J-Rob's KS12024/Western Electric L-8 post at Hifi Haven. If you want to learn more about the Western Electric L-8 and L-9, you can download the pdf file at the bottom of Joe's post.

Read about J-Rob's musings (post #125) about the original KS12024 and Azzolina repro at Hifi Haven.

Late 40s Western Electric Brochure
from www.hifilit.com

The KS12024 horn was from the same era as the WE32A horn that included the venerable WE757A studio monitor, WE713x compression drivers, WE755A, WE756A and WE728B direct-radiator speakers.

Having been a long-time user of the Altec 755A, Altec 32A/C and more recently an Altec 756B, I consider this period as the golden age of design and manufacture of permanent magnet transducers. So when J-Rob offered to loan his personal pair of Azzolina Audio 3-D printed KS12024 horns for me to blog about, it was a privilege and opportunity difficult to pass up.

Azzolina Audio KS12024

I've been a frequent visitor to the ElectraVolt blog but never imagined I would be listening to, let alone reviewing, Charles Michlin's KS12024 reproductions. 

The original Western Electric KS12024 has a 0.7" round opening* but this Azzolina remake was optimized for 1" compression drivers like the Altec 802 that I am using for this review. As relayed by J-Rob, Charles claims the oval (rather than round) aperture sounds better. 

*All the WE horns from this era (including the 32A) were designed for use with the WE713x compression drivers and shared the same aperture size

Just like the original, this is also a true 4-cell compound sectoral horn. AFAIK, this is the model built from an amorphous plastic material. Everything else you need to know about the Azzolina KS12024 can be found here.

Testing

Altec 414A/614 + Azzolina KS12024/802 + 3000H

The Azzolina KS12024 horns were tested in the Altec 2-way system. 

Altec 414A in 614 cab 

Altec 414A woofers in 614 bass reflex enclosures running in full range mode

High-pass XO w/HF eq

Altec 802-8D compression drivers (below) with 16 ohm GPA 34852 diaphragms were mounted to the horns using the above high-pass crossover

Amorphous Plastic Azzolina KS12024 vs. Plastic Altec 32C

Altec 32C + Altec 802

This horn presents a back row perspective and may sound too laid back to those who prefer a closer to the stage presentation. The mid-range is juicy, full and vivid without a hint of shout. While the highs are feathery smooth, silky and airy, which I've only heard from its smaller sibling, the Altec 3000H. Tish (my wife) describes this horn as sublime. I think the 90°H x 40°V dispersion helps provide that holographic and lush atmosphere. 

I've written so much about this horn. Just use the search button on the right hand corner to find past entries.

Azzolina KS12024 + Altec 802

I was initially lured into the 3D-like midrange this horn produced and that lingered on. There's an uncanny realism to male and female vocals as well as musical instruments that renders an "in your room" presence. Compared to the 32C, this horn offers a front row perspective. Yet there isn't a trace of harshness or shout. Definitely a horn that will appeal to those who find the 32C too laid back yet need a horn that doesn't sound like a horn.

It is superior to the 32C in terms of articulation and detail without ever sounding analytical. There's a lot of snap, if I may borrow a term from its owner 😉, just like its stable mate - the WE/Altec 755A.

Azzolina KS12024 + Altec 802 + Altec 3000H

Tish thinks it is as good as but not quite as lush as the Altec 32C. I agree. This is primarily a tonal balance issue. Due to the prominent midrange, the extreme treble frequencies are slightly subdued giving a less airy atmosphere. Adding the Altec 3000H to fill in the uppermost octave helped in approximating the lushness of the 32C. But I still found myself wanting more "hall sound." I speculate that the KS12024's narrower 50° horizontal dispersion contributes to the comparatively austere background. Perhaps I am belaboring this point since my personal preference when I attend concerts is to sit towards the back row so I can relish equal amounts of direct and reflected sound.

Summed up

2 x KS12024 = 100° H x 40° V

These two horns share the same sonic DNA but are genetically modified for different applications. The more up-front and involving Azzolina KS12024 betrays its theatre heritage versus the mellower 32C, which was intended for near-field monitoring. I can't help but wonder if a horn design combining the virtues of both designs is a possibility.

Magnavox CDB473 and Philips TDA1541

With barely 400 CDs and just a handful of SACDs and DVD-As in my collection, I didn't invest heavily on silver discs as much as I did on LPs. Likewise, I've spent much less on digital playback hardware.