Thorens TD-165 RCA Terminals, Static Electricity, Stylus Quivers

[avantbored]

Hi all,

Continuing to troubleshoot an issue I have on my TT, and I've noticed something odd (to me). Hoping others can shed light on this. I provide a narrative of my troubleshooting journey, but if you want to jump down to get to the meat of the question, it is #4 in this post.

Stereo Set-Up:

Thorens TD-165 || ATVM95SH
Nakamichi PA-7AII
Nakamichi CA-7A


1. Stylus Quivers

This troubleshooting journey started with my stylus quivering/shivering on playback. But my own research, backed by helpful posts, found that the most common issues of this is either a a) compliance issue, b) a failed suspension, or c) a bent bearing.

A) The ATVM95SH is a common combo with the stock TP11 tonearm. I have not had this stylus shivering issue from the beginning (happened within ~200 hours of listening). So I don't think it's a compliance issue.

B) As indicated above, this is a relatively new cart, well below the halfway mark of its ~800 hr. listening life recommended by AT. I've eliminated this as the cause of the stylus quiver problem; I revisit this below.

C) My bearing is fine!


2. I Decide to Send to Audio-Technica, But Change My Mind

I got really frustrated, so I decided to send in the cartridge to AT for a repair estimate. I'd packed it up, then resolved to try one last thing. Slide the Preamp to the right so it no longer sits under my TT (which is on a wall shelf). I also widened the speaker placement. Because I'd removed the cartridge, I also unplugged the turntable.

3. No More Quivers (Kind Of), But Static Electricity Persists

So I rearranged the set up, re-aligned the cartridge, and plugged the turntable back in. Suddenly, no more quivering problem (as described in 1B). I'm pretty confident that my quivering issue is not with the cartridge or stylus or the mechanics with the turntable itself, but with power.

4. What's Going on with all this electricity?

The plastic housing on the left channel of my RCA terminal is cracked. I notice that after playing 1-2 LPs, the latent hum is loud (~20-25% volume). When I unplug/plug it back in in the preamp, the hum is only audible at ~50%.

Other electrical phenomena: Electricity discharges through the tonearm and when I lift a record from the platter.

Plugging/unplugging the turntable has seemed to get rid of the quivering issue. But this is not ideal, and unsustainable. I can hear static electricity discharge through me when I touch the tonearm pole.



The Question: Can this cracked RCA terminal affect the circuit, thus perhaps causing this quivering problem through some kind of extra resonance?

 

[tnsilver]

I suspect your headshell collar (knurled) lock nut is loose. Try to lift the HS lock pin about 1/64" with a pair of nose pliers and then tighten the collar nut on the HS.

 

[avantbored]

I suspect your headshell collar (knurled) lock nut is loose. Try to lift the HS lock pin about 1/64" with a pair of nose pliers and then tighten the collar nut on the HS.

Hi Tom,

Do you mean this pin that I've circled in red on the picture?

Thanks.

 

[avantbored]

yes, the vertical single pin. Use the opportunity to clean the 4 contact pins too with contact cleaner and a tooth brush - or at least with an eraser.

Will give it a go. Thanks.

Incidentally, found an old thread of mine about a Pioneer PL-15 that had a similar tremoring issue (but on volume increase; my Thorens' stylus still tremors with volume up or down). The PL-15's issue was diagnosed as an old foam issue, as well as speaker feedback. I will try that if raising the pin and cleaning the contact pins doesn't abate the issue.

 

[avantbored]

Cleaning the pins is just extra pre-emptive maintenance. The TP-60 headshell can become loose if the knurled nut doesn't lock it tight in place. This may not be the root cause in this case - but it can't hurt.

Can you post a picture of the tonearm in it's rest from the front - with the armtube visible relative to the gimbals?

Tried to get a few different angles. Please let me know if you'd like more (it's right behind me!)

 

[tnsilver]

Neah, this is perfect. The 'dorsal fin' looks aligned and I don't think the vertical bearings had been messed with. It's looking good.

 

[avantbored]

Neah, this is perfect. The 'dorsal fin' looks aligned and I don't think the vertical bearings had been messed with. It's looking good.

Raised the locking pin and cleaned the terminals. Pushed the speakers out as far as wide as my room will allow (and furniture will accommodate). Still tremors on some passages.

EDIT: Also, still hear a bit of electrical discharge when I touch the tonearm.

 

[tnsilver]

Hmm... I've been reviewing the AT-VM95SH specs in the mean time and it appears it's compliance with the TP-11 is border line. It's apparently a little too stiff - but really just by a little. This may explain the inconsistency with sporadic passages in which stray low frequencies are induced, such that the cantilever accelerates into what you describe as tremors and quivering. This also makes the playback extremely susceptible to external feedback despite the excellent suspension system of the TD-165. There's little prospect of trying to reduce the TP-11 effective mass either by some skilled 'botching' of the TP-60 HS, or by acquiring a lighter replacement. Nor, in my opinion, it is worth the effort. I would advise you to try (at least temporarily) a more compliant cart to evaluate and to substantiate this hypothesis.

 

[avantbored]

Hmm... I've been reviewing the AT-VM95SH specs in the mean time and it appears it's compliance with the TP-11 is border line. It's apparently a little too stiff - but really just by a little. This may explain the inconsistency with sporadic passages in which stray low frequencies are induced, such that the cantilever accelerates into what you describe as tremors and quivering. This also makes the playback extremely susceptible to external feedback despite the excellent suspension system of the TD-165. There's little prospect of trying to reduce the TP-11 effective mass either by some skilled 'botching' of the TP-60 HS, or by acquiring a lighter replacement. Nor, in my opinion, it is worth the effort. I would advise you to try (at least temporarily) a more compliant cart to evaluate and to substantiate this hypothesis.

This was a peripheral worry of mine, and hoped it would not become a substantive possibility. Alas. I have heard that Ortofon OM-10's are a good match (VinylNirvana has often supplied them with the 165s he's refurbished), and the Nagaoka Pearls. Probably will try the Ortofon as it's the more cost-effective one for me right now.

Don't know if you saw in the pictures that I have popped the top "Thorens" branded plate to mount the ATVM95SH. Do you think reattaching it would up the mass in a significant way?

EDIT: Also, have found at least one Thorens-branded shim marked "1,5" from the old ADC cart that was on there. I was negligent and did not double-check if the ATVM95SH without the shim was at about the same VTA as the ADC with the shim.

Ryan

 

[avantbored]

The Thorens foilcal has insignificant mass. The shim won't matter unless the TP-60 rear drags on the vinyl or if the TA can't be adjusted parallel to the record.

Hey Tom, just wanted to get a follow up question with you.

This shivering/tremoring thing only appeared after about ~200 hours of listening, as indicated above. Do you really think this might be a compliance issue?

 

[tnsilver]

It's possible the suspension settled during the break-in period and things started to get worst. I just had the same thing with a 165 and a Shure M75ED Type II. Apparently, the person I lent the TT to broke the original stylus and had replaced it with a cheap $12 after market spherical bonded tip. He said it 'worked fine' for a while but started to shake real bad a couple weeks later. I've seen it with my own eyes. It didn't stop until I put an extra 0.5g VTF on the tip and made it track at 1.8g instead of the 1.3g of the original stylus. So yes, it's possible.

 

[avantbored]

Experimented with the VTF last night as well, and the shaking did cease after that.

Would tightening the suspension mitigate the issue as well? So I could use the recommended VTF from Audio-Technica? Don't know if that logic squares.

Ryan

 

[tnsilver]

I'm glad you've worked around the issue. If it's not too much VTF, it's sustainable. I should have pointed out I was talking about the cart's suspension, not the turntable's. It's not meant for owner's adjustment.

 

[avantbored]

I'm glad you've worked around the issue. If it's not too much VTF, it's sustainable. I should have pointed out I was talking about the cart's suspension, not the turntable's. It's not meant for owner's adjustment.

Ah, I see! That's a relief -- did not want to have to open this thing up again.

I have it set about 0.2-0.3 beyond the recommended upper limit (2.2g) for this. Is there a danger zone I should avoid?

Ryan

 

[avantbored]

Thanks for info Tom. Writing again with a quick update.

Ordered a Nagaoka MP110 (will be here in a couple of hours I think) to see if the compliance issue really was the case, and while I was removing the ATVM95, I thought I'd also get rid of the stock foam in the suspension system. Since I've had this TT, even with getting new springs from VinylNirvana, I could never really get that mythical Thorens bounce we strive for.

So I was really surprised that when I tested for the bounce, my unit suddenly became really bouncy without the foam. Had no idea that perhaps the foam was so worn out that it was perhaps hampering the suspension's functioning.

You think this holds any water? Playing now with the VTF at ~2.0, and no shivering/quivering here. But I don't know if it's just confirmation bias, and that the problem will reappear (knock on wood) in a few hours!

What do you think? Would this really affect resonance control because the bounce has improved? The bounce was okay so far, but nowhere near some of the videos I've seen of the first-generation 160 or 165s.

Ryan

 

[tnsilver]

On one hand it's not only possible, it's sensible and probable. The suspension system damps resonances that may otherwise get out of control. I assumed your TT suspension is fine b/c it wasn't mentioned in the OP. I should have probably mentioned it earlier. It's also possible you've leveled the platter, or inadvertently introduced another change. I lost count. It seems there's a different unknown popping up after each of my posts. I hope we've covered the complete picture by now.

On the other hand... The turntable suspension system kicks in only when there's reason for it to. Something needs to set it in motion. It won't bounce on it's own. I've also seen TD's with neutered suspension systems in heavy plinths on solid floors, which worked fine for as long as there was no footfall or feedback. If there was no reason for the suspension to... suspend - all would be fine. What I think happened here is a slight tonearm/cart mismatch with a little too stiff stylus, which was the source of the resonances - that the ill-adjusted suspension couldn't damp. It appears a little VTF had damped it instead.

The Naga should be an inherently better match for this setup - so you could explore further, compare the two carts performance and get to the bottom of this.

 

[avantbored]

All hearty agreements and endorsements to your hypotheses. Given the nature of these turntables (and my own sophomoric but developing expertise with this line of turntables specifically), and that I didn't describe to you in full my room (which, I think, would be kind of unreasonable; I would probably do this if I had plenty of time to do so, but I don't), the foam variable could not have even been something I could have evaluated as "insignificant" -- in other words, I didn't think to mention it, because I didn't think it mattered that much (given the debate about the remove-or-not-remove discussion about the foam I have seen).

I would also agree that perhaps something happened in the re-installation of the AT cart (I used the magnification cover on my silicone plastic stylus cleaner for the first time ever to ensure that the stylus tip was really at the alignment gauge's tip) and the re-tuning; my unit has a gap between the faceplate and the plinth edge at the points where the two front and left-side suspension bolts reside (it's flush at the rear one nearest the tonearm), and I took extra care to make sure it was level.

Your insights about the suspension's function is definitely helpful; I rely on Analog Dept's (and other AK posts) to educate myself, but I haven't heard this yet. That's really fascinating to hear that case about solid floors, heavy plinths, and a neutered suspension. After your helpful insights, and my own research, I would also agree that it had something to do with a slight compliance issue, perhaps the room itself, and the removal of the foam.

The Naga is about 2 stops away. I'm looking forward to installing it in any case, regardless of my affection for the Shibata stylus. Hopefully, my evening won't descend into a VTF adjustment tailspin.

Thanks so much for your insight, Tom. Loving the kinds of conversations AK has. Much more fruitful than other social media platforms. Thank you.

Ryan