Any advice on buying quality vinyl

Cleaning is very, very important. I have had similar experiences with older records and have a dedicated turntable just to dredge out the stuff in the grooves that was loosened, but not removed, with cleaning. Sometimes I have to clean my stylus 2-3 times while playing after cleaning. The work invested makes it worth it for some treasured LP's.

I am by no means an expert on recording and mastering and the changes in the industry from the late 50's through the 1970's. Some of my audiophile friends here in Connecticut seem to be. They say that a lot of the recordings made in the late 50's/early 60's are spectacular precisely because their was less technology involved. The miking was simple (not a "forest of mics"), recordings were two-track and on tube-driven equipment. The dynamics of the original were preserved because there was little, or no, compression used, especially with the DECCA and other UK labels. Steve Hoffman claims there is a “breathe of life” in these simpler, early pressings. My listening to these seems to confirm this. Some early DECCA stereo pressings are startling in their realism.

On the DGG red stereo "Alle H" pressings from the late 50's and early 60's and their sonics, I will just maintain that my experience differs from others. I have found some to be world-class...... and black quiet. Some of the DG pressings are excellent as you noted.

The general opinion I have read is that Dynagroove (tech) destroyed the sonics for those with high-end systems, but improved the sonics for those with low-end or mid-fi systems. I am always running into advice that says if you're playing a Dynagroove record with an elliptical stylus (which came into popular use shortly after the introduction of Dynagroove) that you should switch out the cartridge and use one with a conical stylus with a .7 mil spherical tip to get a better audio experience from them.

I will add that cleaning older records is very difficult because of several factors, including the fact that, according to a paper I read published by SHURE, the stylus running at 33-1/3 rpm’s contacts two microscopically small points on the groove walls. The pressure on these points of contact is approx. 26 tons per square inch. The implications of this are obvious for stylus wear. However, I believe (no proof yet) this same pressure, and the heat of friction on the groove walls, also momentarily softens the vinyl and causes debris to stick to the groove walls. Normal cleaning methods have a tough time removing that debris.

Also, this same article talks about the effect on the stylus causing wear "flats" that act like chisels that fracture the vinyl wall. The wave crests created by this condition also contributes to a worsening of the reproduction, but my opinion is that the tiny shattered vinyl bits get stuck in the bottom of the grooves where they are very difficult to remove with micro-fiber pads. Perhaps this is why playing a record shortly after cleaning dredges out the stubborn stuff. I used a very fine-tipped, and inexpensive, conical stylus for my "play-cleaning".

The paper was originally published in 1954 when cartridges ran at higher weights and styli were not as good as we now enjoy but, many older records could be very hard to clean because of the playing that they saw early in their life.

Too much information perhaps, but I find this stuff very interesting....

@edgewear, 

I applaud your cleaning procedures. I have never tried Vinylzyme. Residual organic (mold) could be the source of the running noise I am hearing on older RCA records. I have been trying to mechanically agitate all the crud out with various materials and procedures. I have kept everything manual but have tried ultrasonic machines and I don't think they are worth the money for the result- even though the science is very compelling. I have avoided using targeted chemistry as an aid because I wanted to keep the cleaning fluid I use very simple: Dawn and distilled water. No alcohol. No wetting agents. Maybe its time to experiment. Thanks.  

@playpen, 
I like your tenacity. I think the reason the cleaned records may have sounded horrible after cleaning was that the embedded debris had its bond broken by the detergents and maybe the change in the electrical charge- enough to be dredged out by your stylus. I have found the same to be true which is why I mentioned earlier that I actually use a turntable to "play-clean" as part of my method. 

My apologees to the OP for hijacking this thread.  

I have found in discussions that there is a need for clarifying terms.

I use "original pressings" to describe ED1 or original releases.

I use "first stampers" to describe the first stamper sets in a run. Later releases and recuts can also have first stampers. Also, I think first pressings of Columbia and RCA releases don’t always use "1A" in the deadwax.

As I said earlier, for me, pressing order has the biggest effect on the sonics, besides condition, and there’s no way to know the pressing order except if you look for white label promos with the right matrix numbers. In general. WL promos are worth the hunt because the sonics seem to be better.