Strange turntable/speaker issue


OK, this is going to be lengthy, but here goes....

I have a feeling someone else has experienced this, and want to get some advice in how to correct this issue.

Some background; I could not keep myself from wondering just how good the old vinyl I had boxed up for years would sound compared to my digital set-up, which sounds pretty good to me right now. But, out of curiosity, I finally dragged up my old turntable that has been stored in my basement for 15 years (since I moved in), and probably have not used it in at least 25-30 years total. Originally purchased in the mid 70’s, it is a basic Kenwood KD-2055 with the heavy composite ‘granite’ base. After getting it set-up, I realized very quickly the old Ortofon OM 5E cartridge I installed in the mid-80’s was not going to ‘cut it’, and could not compete with my CD’s, files, or streaming set-up. So, after doing a bit of research, and not knowing yet if going back to some vinyl listening would stick, I purchased a Grado Premier Red, mounted it in the shell, set it up, and yes, it is a vast improvement. Much better overall dynamic range, soundstage, imaging, etc. than the Ortofon 5E. I thought to myself, ‘this may just work’. But, as I was checking some things out, I realized my Vandersteen 2CE’s were actually moving quite a bit (volume was a bit high, but not overly so). That is no easy task. I got back behind the Vandy’s and the rear 10” acoustic coupler was actually moving in and out at a fairly rapid speed, thus causing the speakers to actually move on the anchor stands quite noticeably. Now, this was not really effecting the sound, or creating sound in and of itself, but it can’t be good. First thing I thought was I had misconnected the cartridge leads at the shell, so double checked, and they are connected as per the Grado instructions. BTW, this could have been happening with the old Ortofon as well, but I may not have noticed. Overall, while playing music, the turntable also seems highly sensitive to moving/walking around as the music was playing without distortion. I don’t have to tell you, this does not happen with CD’s or digital files.

I have my turntable on top of a pretty beefy steel frame with wood shelves 60” long ‘TV stand’, as yes, my system also acts as a ‘home theater’ setup, as well as a 2 channel set-up for music. The Vandy 2CE’s are my ‘front’ and 2 channel speakers driven separately by a B&K 125.2 power amp. The lowest shelf of this unit consists of CD storage, the middle shelf my B&K amp, Yamaha V871 receiver (I use as my pre in 2 channel, although it does little as the front channel pre-out’s go directly to the B&K, and while playing music I run in ‘pure direct’), CD player, and PS Audio DAC which all my CD’s, files, and streaming runs through. The top shelf is my TV, Elac center speaker, and my turntable. At this time I am using the Yamaha phono stage (that could change soon, as I think a dedicated phono pre-amp would help things a lot). The TV/equipment stand sits directly to the side of the right speaker, not between the Vandy’s, as they are on each side of my fireplace. The turntable is about 4 1/2’ from the right speaker, and right about the same level of the Vandy’s front 8” woofer.

So, all that said, I have a feeling what I am getting is sonic feedback between the speaker and turntable, perhaps with the cartridge acting as a microphone getting hit with the sound waves from the right speaker, even with the dust cover down. Because of room and layout constraints, I have very limited locations for all this stuff, so not sure a relocation of the turntable is really possible, and if I did, would have to get long male/female RCA interconnect extensions to get back to my Yamaha, or any future phono pre-amp, which would still have to run back to the Yamaha probably utilizing the analog Audio 2 inputs, as the Audio 1 inputs are serving the PS Audio DAC.

So, is sonic feedback what I am witnessing? Or could it be something else? And is there any easy solution? I doubt isolation feet will solve anything if feedback between the right speaker and turntable is the problem.


128x128bkeske
@jnorris2005 Interesting to consider. One note though, when I say wood shelves, these shelves are supported fully by a metal flange and frame and also a composite (layered wood) shelf that is as thick as the metal frame supporting it, or 1 1/2”. I’m not talking about 3/4” shelves here, and one of the reasons I bought this unit, as it had to support my B&K amp, Yamaha reliever, CD player, and PS Audio DAC over 60”. Thus, it had to be sturdy. As an architectural designer, and builder, believe me, I consider these things. Thus, I think the table is very sound, though may not be isolated from other factors.

I wrote this earlier, and then got busy with, of all things, work, so just now catching up.

I’m going to try out a few things, and get back to you all.

I really appreciate all the help, and am sure with those who have had similar experiences a solution will be found.

OK, off to try some of the above tests and I’ll repost back.

Dear @bkeske : Other possibility is that the resonance frequency between the Grado cartridge and the Kenwood tonearm is  totally out of range and I said that because the original  cartridge that came with the Kenwood had a low compliance of 7cu when your Grado one has 20cu.. Maybe to high for that tonearm.

Regards and enjoy the MUSIC NOT DISTORTIONS,
R.
OK all, interesting finding.

@viridian Yes, I didn’t really want to pull the plug with a record playing, but I did. Turned up up volume, and no ’howling’ at all.

@millercarbon I didn’t want to, but finally moved some furniture out of the way, and set the turntable on the floor, right next to the stand. You are right, this eliminated virtually all of the 10" acoustic coupler rapid movement/rumble (not a noise, just the rapid movement).

So, damn I thought, I really don’t want to put this thing on the floor. So I tried a couple of things; what if I put a thick piece of styrofoam below the whole table on the shelf? Have some in the basement from various exquipment packaging, brought it up, set the table on it and it was much much worse. Next, got some large tiles I have in a box, figured perhaps what is necessary was additional firm support. Nope, didn’t help. In fact, it seems anything I add under the feet, made the situation worse.

Took off the platter and belt, locked the arm, and removed the head shell. Turned it over and inspected the feet. Over the years, 2 of the three feet had somewhat collapsed at the isolation sections, and two still had the iso section intact on the feet where they screw into the base.

Which got me thinking...seems to me, more isolation, or anything, under the feet is created more issues, not less, so, what if I take off the feet entirely so the table base sat right on the wood shelf? Looked into the service manual, made sure the base would come off easily, it would, so removed it, and then removed the feet entirely (the screw attachment to the feet were on the inside base side). Reconnected everything, put on a record, and lo and behold, probably 88% of the sub/coupler movement was reduced/eliminated. Only when I cracked it way up did it start acting up, but again, way beyond the volume level with the feet on.

But, the vent ’grate’ to the motor probably needs room to breath (ya think? ;-) ), so this is not a good solution, but what it told me was the more I could ’connect’ the table and the stand/shelf together, the better off I would be, short of putting the table on the floor. This seems reverse thinking of what we tend to believe with most audio equipment, but I may have to look for ’solid’ replacement feet, and not feet with any type of absorption or isolation qualities.

I think my problem is that I have an old house, with fairly bouncy old wood floors and structure, and the large Vandy’s sitting on the floor transmit a lot of energy and movement into the floor via the anchor stands, and thus, transmit the same into the large loaded stand adjacent to them. So any ’typsy’ feet on the stand is going to react negatively, especially ’tipsy feet’ of a turntable.

So, the filters that are coming are useless to me, and I’ll probably return them immediately. Good news is that the Schiit Mani is a good choice for a phono stage, as a filter is not really necessary.

So now I have to figure out what type of solid raised platform or feet I can get which will be ’as connected’ to the shelf/stand as possible, not isolated from it. The only other options are to set thee table on the floor, get a separate turntable stand, or get one of my carpenters to build a wall mounted shelf. None of which I would prefer to do.....yet.

I can’t thank you guys enough for all your thoughts and ideas thus far.
The U-Turn Pluto is a very good, inexpensive phono preamp that has a subsonic filter. For what it’s worth, Michael Fremer published 2 files played back with the Pluto and the Schiit Mani and listeners preferred the Pluto by more than a 2-1 margin.

https://www.analogplanet.com/content/u-turn-pluto-versus-schiit-mani-votes-are

If filtering rumble frequencies is an issue for you, I would recommend the Pluto.

LarryRS