Thursday, 29 March 2012

More Turntable Action

I had not expected to hold onto the White CEC turntable for long and I didn't, but as usual I tuned it up somewhat before selling. I put the right belt on it (but should find a home for the one that came off, as I think it was just the wrong size, not worn out) and replaced the headshell with one that was not broken. That and the lid polishing was certainly "value added". I did not make a huge profit on it, but it did go a long way to help pay for the next turntable!

Sony PS-2400 10

Today I picked up a Sony PS-2400. It's a solid quality beast of  belt drive machine. It sold for 39,800 Yen back in 1971, and probably was not available very readily in North America. There were several variations on the theme in higher end and direct drive versions as well according to The Vintage Knob.

It's fully manual and equipped with a very nice s shaped tonearm. This may be the only turntable I currently have with Vertical Tracking Angle (VTA) adjustment. The tonearm is essentially adjustable in height at the pivot end, which ultimately controls the angle at which the stylus contacts the groove and affects the sound. The vast majority of basic consumer tables do not have this and they work well enough but its not ideal. There's a more complete, but still not overly technical description of VTA here:

Sony PS-2400 3

Sony PS-2400 9

Unfortunately some of the veneer is a bit damaged and, even worse, the lid has a chunk missing from the corner. I have some thoughts about how to fix that, but that's for later. This one is worth fixing up as much as any table I've owned, and I'm going to work at it.

Sony PS-2400 7

This turntable will be a keeper. I think my Sansui SR-525 is that much closer to going up for sale now...

Sansui SR-525

Thursday, 15 March 2012

Out with some old, in with some old...

Several pieces have changed hands this week.

About a year ago I picked up the original AR amplifier in a a Craigslist deal. I came across it while searching for a Marantz tuner and found it advertised at the same time as a tuner and pair of EPI M50 speakers. I bought them all and a few records at the same time.

AR Amplifier

I knew little about it at the time I saw it but later found that it was very highly regarded and probably quite valuable. Not valuable enough to get rich on but enough to take a chance on. I brought it home and used it for a while but found a few things lacking.

It sounds fine I guess, but lacks inputs and some of the controls that might help in my space. I did think it sounded a bit thin. Maybe re-capping it would help that, but I decided it was worth more to me sold than in a stack of other receivers and amplifiers so sold it was.

Before I did get rid of it I was determined to clean it up a bit, which I did last weekend before the interested party showed up. In some respects I wish I hadn't bothered. The black case seemed to have kind of a soft, not quite sticky coating to it. It still seemed sort of black...sort of. Black like tar.

In fact that was probably what it was, cigarette tar! I am not sure but I think that was what it was. I spent over an hour rubbing it down with water, alcohol, dish soap, WORX (a natural hand cleaner I have), Goof-Off and various other means to try to remove the crud. It more or less came off, and eventually I gave in. I ended up with some lifted paint as well, but it did look better. The knobs were also a bit cleaner, and overall it looked pretty good.

If I had kept it I probably would have either really stripped and powder coated the case, or maybe built a wooden case for it. However the guy who came over liked it as is and took it home for my asking price with no argument. He had one before and seemed keen to add it to his collection even though he had paid about $200 in 1970 dollars back then and mine worked out to a bit more!

Here's another pic:

Ikea cd shelf 2

Anyway, I also made a couple of other deals this week.

My very first pair of decent speakers was a pair of Mission 700 that I bought in Fredericton back in around 1978. I set those up with a Taya turntable and a Technics SA-300 receiver, all of which were bought from Rick at Magic Forest Music Store which was in the basement of the Student Union Building at UNB at that time.

Last year I acquired an SA-400 Technics and later the SA-500 so had that part of the ``original`` system, but yesterday I bought a set of Mission 700s speakers, which are a bit newer but quite similar to those old ones I had. I also traded a pair of Koss M65 mini speakers, one of which I had re-foamed, for a White CEC BD1000 turntable. This turntable was very similar to the Taya I had back then. CEC in fact made the Taya I am sure as well as many other turntables of that era.

The speakers look pretty good and sound fine, but will look better when I get to work a bit on a few scratches and marks in the finish.

Mission 700s

 The turntable needs a bit more work, being quite scratched up on the lid, and otherwise a bit mangled. It didn`t help that the guy met me in the Safeway parking lot carrying the turntable in his backpack. The platter and mat were just bouncing around inside the lid! Fortunately he had locked down the tonearm and the cover was not cracked. In addition the suspension screws were still tightened down so not too much could move.

White CEC BD1000

The lid has the usual scratches, and some sticker residue but other than that it should clean up fine. I had a belt that fit, as the one that was included was either the wrong model or was just too stretched. The Audio Technica cartridge and stylus seem to be fine at first examination. The headshell actually had a crack in it it but I think I have successfully epoxied that.

White CEC BD1000 Turntable

A cracked headshell was itself odd, but I figured out why. For one it is plastic. That is not necessarily a bad thing though most good shells are metal. Plastic is pretty inert sonically, electrically and magnetically. Metals might not be, but they might be stronger. This headshell did not have a chance though as the cartridge was installed in such a way as to clamp it over a grounding wire and so that the stylus could not be pushed on to the body all the way. Not surprisingly the headshell cracked as  the cartridge screws were tightened. I glued, reversed the screws, moved the grounding wire, and it should be fine now.

The lid and other issues I will get to later...

Friday, 2 March 2012

Grooving on a Tangent - Harman Kardon Rabco ST-7 Turntable

After a week of my car being in the shop, and work getting in the way, I was finally able to get down to Point Roberts to pick up my most recent turntable acquisition.

This one is the most exotic yet, and will hopefully hold top spot for quite some time to come. Considering it cost me more than any table I have purchased recently I hope it does. Of course it seems for now to need nothing in the way of upgrades or maintenance as was the case for many of the other pieces of audio gear I've recently acquired. The fellow I bought it from on AudioKarma did a bunch of work on it already so there is little for me to do, except perhaps polishing some blemishes out of the lid which I am not only getting pretty good but it costs me mostly just time.

Harman Kardon ST7t

The turntable in question is a Harman Kardon Rabco ST-7 and has, as the owners manual says, a "straight line tracking system." Otherwise known as linear or tangential tracking this method of tonearm design essentially means the tonearm does not travel through an arc, but always stays at a tangent to the groove. In theory at least this should sound better with less potential for distortion.

tracking error

The principal reason this should be better is that the stylus is always positioned in the groove in the same way that the record cutting lathe created the groove on the master discs. Doing this ensures the stylus reproduces the sound accurately. When a tonearm describes an arc as the vast majority do there is simply no way to have the stylus always at the correct angle to the groove. The best you can achieve is a compromise, though that can be a very good compromise and for most is more than adequate for good sound reproduction.

I've always been intrigued by linear tracking turntables but have never seen one I would either want to own or could afford. They only represent a very small percentage of the turntables made and in the shops I go to usually the only ones I ever see are the lowest end versions and usually in very bad shape.

Rabco Tonearm

I honestly am not sure how much better this type of turntable can sound for me. It eliminates what is know as "inner groove distortion" which is concern for conventional tonearms. In the inner grooves the difference between the angle of the stylus/tonearm to the groove is the greatest so there may be more audible effects or differences from the way the source material was added to the disc. I am not really that critical a listener, rarely sit in the sweet spot and really listen, and don't have the ultimate is system quality so...

In other words the potential differences are really quite subtle to most mortals. However even if I can't hear as much of a difference as some folks, the engineering behind this design also fascinates me.

HK Rabco drive

There are various ways that the tonearm follows the groove. In the case of the Rabco ST-7 this is done by a secondary belt driving the tracking shaft. Riding on that shaft is a rubber tracking roller and based on the easily adjustable tracking angle the speed at which the cartridge moves across the record can be changed. Because there are varying lengths of music on record sides, there are not always the same number of spirals so the rate at which the stylus reaches the centre of the record will also change. Being able to adjust this angle can compensate for this variance.

From a maintenance standpoint this arm and drive system should need little work. The tracking roller is know to wear out or disintegrate but relatively easily found and modified O rings can be used in its place. The belts are also supposedly quite normal in size.

Rabco tonearm with Audio Technica

Installation and alignment of the cartridge can get tricky. Harman Kardon did sell these with a gauge that would come in very handy, as would another tonearm wand for easy swap of cartridges, so I will be keeping my eye open for those.

This one is well set up right now, so hopefully these issues will be sometime down the road. For the time being I will simply try to enjoy the sound and the Bauhaus like design.