Vinyl Newbie - So Many Questions!


New to these forums and new to vinyl, but longtime audiophile, so I feel comfortable saying that I know what I’m hearing but can’t figure out why. 

It would probably help if I summarize my system to aid in troubleshooting:

Marantz TT 15S1

iFi Zen phono preamp

Naim Uniti Atom as streamer/preamp/dac

Conrad Johnson CAV-45 S2

Klipsch Cornwall IV

I’ll start with the easy one

1.  I followed the setup instructions for the Marantz tt meticulously. Every time I start the motor, the belt squeaks and slips on the motor pulley before getting up to speed. It’s annoying and really cheapens the experience. Is this normal?

 

2.  The sound quality ranges from very bad to very good, largely dependent on the record. I don’t have a large collection as I just started with vinyl, but many of these pressings sound absolutely terrible. Many sound distorted and compressed. Many have tons of clicks and pops. I double checked the settings on my phono preamp which is really just moving magnet. There aren’t a lot of settings. One for MM and three for MC. I connected the phono preamp directly to the Conrad Johnson instead of the analog input on the Naim and while it does sound “better”, it’s mostly the same. 
 

I don’t have another cartridge or phono preamp to swap out and try to isolate the issue. Could it simply be that the phono preamp is defective?  It seems that if the cartridge was defective it would just all sound bad.  Could it be that my system is revealing enough that it’s showing the limitation of the iFI?  I just think it would sound “good” all the time, but never really “great”. Could it be that all of these pressings are so incredibly crappy that I’m hearing just how bad they are?

The couple of “mainstream” records do sound pretty good. Namely Gregory Porter, Adele, Gary Clark Jr, Miles Davis, John Coltrane. But even a couple of those have inconsistently cut holes for the spindle (some of them bind), significant warps, and some off-center labels. The independent stuff is all over the map. A couple of the John Prine pressings sound very good, but have soooo many clicks and pops it’s ridiculous - even after cleaning. And one of them wouldn’t even go on the spindle because the hole was so small. 
 

Anyway, I’m just perplexed and pretty annoyed. I’ve debated buying another turntable (with cartridge) and phono preamp just to see if there’s any change.  Any suggestions?  Is that my best course of action - to just buy another preamp and cartridge to troubleshoot? 

doodledan

There may be an issue with the Marantz setup instructions.  Look into the forum discussion below.  Hope this helps.

 

Marantz  TT-15S1 Contradicting Setup Instructions

Thank you go all of you who have responded to my questions - it's been a tremendous help.  I wanted to provide an update and, perhaps, ask one more question.

I tried a different cartridge (Rega Super Elys) that I picked up here on AudiogoN for a reasonable price - just to rule out any issues with my cartridge.  While it sounded "different", it certainly wasn't better and most of my issues persisted.  I took that to be good news.

Next, I tried another "budget" phone preamp (a Schiit Mani, also picked up here on AudiogoN), to rule out any issues with my iFi Zen Phono.  I figured that if I bought stuff cheap enough, there was little to no risk and the troubleshooting could continue without spending needless money.

In the meantime, I followed all of your advice and walked through the setup process of my turntable again. I'm not sure if I heard any improvement, but it helped me feel confident that I had done things properly.

All of this lead me to the conclusion (as many of you already pointed out), that I needed a "real" phono preamp - something more in keeping with the quality of the rest of my system.  Against my better judgement, I got on eBay and bid (and "won") a Lehmann Audio Black Cube SE.  Unfortunately, there was something loose rattling around inside the external power supply, so I didn't even risk trying it out and promptly requested a return authorization.  Next, I purchased a Dynavector P-75 Mk3 for a very good price and was optimistic that it would be "the one".  Sadly, I experienced a terrible ground loop that I absolutely could not eliminate, leading me to conclude that there was an issue with the unit itself.  The seller hadn't used it in a few years, so couldn't rule out that there was a problem.  He kindly refunded the purchase and I sent it back to him.

Finally....I purchased a Musical Fidelity M1 ViNL phono preamp from a very nice seller here on AudiogoN which arrived yesterday.  I promptly unpacked it, marveling at how substantial and beautiful it is.  I hooked it up directly between my turntable and control amplifier (integrated) and put on the first record.  It was a revelation!!  This thing is so quiet and dynamic, it's amazing!  I have lots more listening to do, but I can finally hear where vinyl is "as good as" a nice digital front end and clearly has the potential to beat it. 

All of which leads me to one more question, if you will indulge me.  As you may recall, my cartridge is a Clearaudio Virtuoso which is a ~$1,000 moving magnet cartridge.  I would like to try moving coil but am wondering whether something "affordable" like the Denon DL-103 could possibly equal or better the Clearaudio, or is that unrealistic?  If so, what would I need to budget for something that would clearly surpass the Clearaudio - and do you have any specific recommendations?  I like to keep it under $1,500 if at all possible.  

Again - I want to thank you all for your thoughtful replies and assistance.  It's been a struggle and, at times, incredibly frustrating, but I feel like I'm seeing some light at the end of the tunnel and am looking forward to buying more records and actually enjoying my investment.  

 

You have a decent turntable.  I owned a Clearaudio Emotion for quite a while and it is very similar to your table.  You have a really cheap phono stage.  

Here are a few suggestions.

Try getting a really thin sheet of sorbothane and setting the motor on that.  Thin being the key, if it's too thick the belt may ride too high and come off the platter.  The sorbothane can leave stains on things, so take that into consideration.  Blue tack might work.  The thing I least liked about my Emotion was that the motor could move around.  The sorbothane really helped.

Don't be afraid to give the platter a little spin and give the motor a little help to avoid the belt slipping.

The ticks and pops become less noticeable as you get better gear.  People are often surprised when they hear a really good analog setup and it's dead quiet.

Many new pressings have a lot of ticks and pops.  Static electricity can also be an issue.  Cleaning records can help with this, and there are devices that are purported to reduce static (I haven't tried any, so won't comment on their efficacy).

There are places you can get information on the quality of different pressings.  The Steve Hoffman forums are one and you can also look up the release on Discogs and see ratings and often there will be comments about the pressing quality.  Unfortunately, it's often a crap shoot - one person will get a great copy and the next person will get a poor copy.

If you are open to an upgrade, check out the Parks Puffin.  I think they are under $500 new.  It's a great phono stage at its price level and has a "Magic" setting that will reduce clicks and pops.

If you have a hi-fi shop nearby, take the table in and have them check your setup and the cartridge.  That shouldn't cost much.  

Goofy, I don’t get the impression that some LPs play fine, just that some are less objectionable than others.

I reviewed the Marantz TT user manual. Since Marantz sells the TT, the phono cables, and the Virtuoso cartridge as a package deal, it seems unlikely that cable capacitance would be an issue, although the Zen has a highish input capacitance, and I can still easily imagine the cables add 100pF. However, the OP needs to check out setup first, VTA, VTF, grossly accurate alignment. As I inferred above, one possible way to ameliorate the effect of the high capacitance load on the cartridge is to reduce the input resistor load, which is to say reduce its value which paradoxically increases the load on the cartridge by a tiny amount. I still think it would be worthwhile to try 33K ohms. The only way to do that with this rig is to insert a resistor in parallel with the fixed47K load. This can be done with the inexpensive kit sold by DB systems.

i just looked up the loading kits made by DB and sold by Acoustic Sounds. It’s mainly for MC cartridges, but they do include a pair of blank adapters that could be used for any value needed.

I've had a look at your TT Model and it is a model that has quite a few good appraisals, it looks more than adequate to support your needs at present.

I've had quite bad experiences with Modern Pressed Vinyl sourced through the larger supply chains.

Fortunately these purchases are supplied with good returns policies, so it is prudent to choose to make use of this side of the service.

Also a MFSL LP might be a bit more pricey, but can prove to be a good benchmark to compare other vinyl purchases against, when another LP is noticeably inferior in the comparison, returning it and receiving another copy will in most cases prove to be a corrective measure, where a noticeably improved LP is received.

Avoid buying discounted copies of a New Release LP from larger supply chains, as these are possibly items that are already returned by customers.

The TT Belt on your TT, is claimed to be a Silicone Material, is there any sign of a wetness on the belt, as a Silicone Oil residual can easily create a slippage.

The TT's motor is a design that is very accurate for speed stability and I doubt if it has a fault, but maybe should not be ruled out.

The Stylus being quite dirty can cause a replay to sound quite distorted and unenjoyable, or worse a damaged cantilever can produce a replay that sounds very incorrect and concerning. 

It looks like there is a bit of hill to climb, to get you to the place where the Vinyl side of the system, is proving to be quite satisfying.            

I have a Linn with a heavyish platter. I always hand start it by spinning it first. Otherwise you will soon stretch the belt.  With this assist, belt lasts almost forever. 

doodledan, if your motor is sliding around, try sitting it on some dampening material. That is, if it doesn’t cause a height issue with your belt. Herbies Audio makes some thin but affective dampening sheets which may help.

Additionally, I agree with the previous comment regarding the level of your tonearm. Just for grins, can you raise and lower your tonearm by around 1/16th and play it in those varied positions? With the head shell slightly raised, you ought to get a fuller richer sound. With the counter weight slightly raised, you should get more detail.

The difficulty with this problem is why your noise problems are inconsistent.

lewm, it doesn’t make sense why some records play fine while others create unwanted noise. I agree that resistance might lead to unwanted noise but wouldn‘t that be consistent with all pressings?

So after reading more about your TT I learned what you have experienced, the motor is isolated from the plinth thru a hole and it sits on the self and that you might move it everytime you turn it on or off ,  I was going to suggest blue tac , I don't think it would hurt the finish but better safe than sorry .

The total capacitance can be tricky , that is why a phono preamps with MM loading selections are being recommended . Mine has values of 0, 50, 100, 150, 220 and 330 and am using 50pf with a Soundsmith cartridge that recommends 100 to 300pf . I remember measuring the capacitance of the phono cable to be 30pf but most don't folks have a capacitance meter .

John Prine !  I have all of his records , many of them first pressing but I'm very impressed with the O'Boy pressing and the new Rhino Start Your Ear of Right releases of his first 3 albums .   Miles Davis " Kind of Blue "  I purchased a new copy and returned it , it was either DOL or WaxTime but the Columbia legacy pressing is fantastic .  Vinyl is a lot of work but rewording in the end .  You are getting a lot of good advice frommembers of this forum .

 

 

First, get the possible bugs out. Then, if you still feel there’s a problem, think about a phono stage upgrade. But I still say you ought to be getting better results with what you have. IF the cause is an excessive capacitance load, the effect might be ameliorated by reducing load resistance. DB Systems make a kit that might help. By placing selected resistors in parallel with the fixed47K load, you can reduce R . I suggest trying 33K, for example, just to see what that does to sibilance, ticks, and pops.

@lewm  - That’s very interesting. I am definitely hearing exaggerated sibilance in addition to the clicks and pops. I have to point out that a couple of records are virtually noise-free. It seems that when the recorded material is at a quieter passage, the sound is quite good, but when the dynamics increase there is distortion, almost as though the gain is too high on the preamp. For example, if I set the iFi at the next higher gain setting (high output MC), it’s a similar (albeit greatly exaggerated) type of effect. 
 

@noromance  - I’m reluctant to use blutak because my table is sitting directly on an old walnut credenza (my deceased father’s old stereo cabinet), so I’m afraid to damage the finish. But maybe an isolation platform would mitigate that concern. That’s a very good idea.  Decware is a great recommendation!  I’ve read about the spin-clean but didn’t know if it was more trouble than it’s worth. 
 

I just ordered a stylus pressure gauge, so I’ll at least be able to check that. I did use a protractor to set the cartridge and I’m pretty certain that the tonearm height is correct, at least per the mfg recommendations. 
 

It sounds like, one way or another, I’m looking at the need to upgrade my phono preamp. In the meantime, I think I’ll just order an audiophile pressing of a known good recording and see how “good” I can get it to sound. 

 The sound quality ranges from very bad to very good, largely dependent on the record.

I have been there  and done that many yrs ago. I came to understand that I had a weak link in the chain. A system is only as good as its weakest link. in your case, it is the IFI. You system is crying out for their equal  so they don't get blamed. Your TT casts $2k, your Cartridge costs $1k and your phono preamp costs $200 or $0.2. See the imbalance? indeed price is NOT a complete indicator of quality. BUT its a good place to start and it is an indicator. The phono preamp is as important as the TT itself or any other component in the chain. It handles the most fragile of signals. Get a good Phono preamp that costs as least as much as the cartridge.

Let’s forget about the quality or lack there of of new vinyl issues for the moment. You actually have a system there that ought to be capable of very nice better than mediocre phono reproduction. So it is worthwhile to analyze that system first before casting aspersions on the LPs themselves. Are you saying that the RCA’s between your IFI phono and the CJ amplifier are something called “monolith”?The capacitance of those cables does not matter much in this instance. The only thing that is important is the capacitance of the cables between tonearm and the phono inputs on your phono stage. The responder who said you’re ok for total capacitance is wrong because we don’t yet know the capacitance added by the ICs between cartridge and phono stage. I’d bet they add at least another 100pF, so your cartridge is likely seeing >200pF when it’s designed for 100pF. It is going to be a bit difficult to rectify this problem, if it is the reason why you are hearing ticks and pops so often. What happens is that the relatively high inductance of a moving magnet cartridge in combination with the load resistance and with the total capacitance results in a high frequency resonance. With MM cartridges you have to be careful to keep that high frequency resonance well above audibility. When you have too much capacitance, that high frequency resonance will move down in frequency into the audible range. This can result in exaggerated perception of ticks and pops.

I wish there was a simple way to post pictures. The motor literally sits on the shelf, completely independent from the plinth. Since there is already tension on the belt between the motor and the platter, it’s very easy to move the motor and end up with it in contact with the plinth. The only thing holding it in place is a bit of friction from the little feet under the motor and inertia.  
 

I listen to a lot of “independent” type artists who tend to be on small and sometimes even their own record labels. Unfortunately, the production quality is just very poor. Im going to have to rethink my vinyl purchases and stick with stuff that I really want to own that’s either on a larger label or just purchase audiophile pressings. It’s more than a little disappointing that new vinyl seems to be such trash. 
 

In a timely YouTube video posted just yesterday, Paul McGowan talked about that very subject and seems to support what I’m hearing; namely that much of the new vinyl coming out is just a highly compressed digital transfer to vinyl. Much worse than just listening to a CD or highres stream. 

P.S.

I don't think that the motor housing should be moving , if you hold the housing can you then move the pulley ?  I beleive that only the pulley should be floating .  The three screws you see on top should be holding the motor housing to the plinth .

 

 

doodledan

I looked at images of your model TT and the motor mounts are similar to my TT , on mine there are springs that level or keep the motor spinning so that it does float and the belt rides perfectly horizontal on the plater  .  This could be your problem , you'll have to take the motor housing apart to see .

You NEED VTF scale . Your cartridge requires 2.2gms +/- .3 , it also suggested 100pf loading . Your iFi is set at 110pf  so your OK there .

Your experiece with new pressing is very unlucky , I stay away from the EU pressings that do not have the original company label on them / or the ones that don't pay royalties .

Good Luck

 

 

 

So the phono cables coming out of the Marantz are hardwired to the tonearm, so I can’t say for certain what Clearaudio uses (they make the TT for Marantz). The cables coming out of the iFi are (cue the eye rolls) Monolith 3 ft RCAs. 
 

I just checked an Amazon review where someone reportedly measured theee cables and found them to be quite high in capacitance (65 pF/ft), so that might be an issue. What do you think?

Yes... a phono preamp is meant to plug into a preamp... it should be OK.

If your preamp sounds ’right’ with CD, etc. ... it should work with ifi

Go to Clear audio to get specs for your cartridge... 47k ohms should be OK.

GET A FORCE GUAGE.... they are cheap. You cannot properly set up your TT and cartridge without one.

Once you have made sure your cartridge is setup... you can play with VTA (height of tonearm) start at dead level, raise or lower to your preference.

Make sure your records are clean. Get on u-tube and watch setup videos and cleaning videos... helps newbies.

If your cartridge has collapsed... clear audio has a trade in , trade up program.

BUT... more than likely it’s your setup skills... no offense... try again with the proper tools.

AND... the belt. Take it off, put in a bag with a little baby powder... shake it. May help. Belts stretch..they are a wear item... you can replace it.

Recommended load capacitance for your Virtuoso is 100 pF. MM input C for the Zen is 110pF. So even before adding C due to your phono cables, you are at the outer edge of the C your cartridge “likes”. Cables can easily add another 100pF even if short in length. What cables and what length?

Sounds like you have some very decent equipment and things just need tweaking. You've got some great advice here so I'm sure things will fall into place. An ultrasonic cleaner is not a necessity but clean records are and there is plenty of advice using various methods to be found. I am a fan of solutions with no alcohol and have had great success with Disk Doctor and recently a fantastic lens cleaning solution called Bi-Oh! Disk Doctor solution is no longer available :(

As for cleaning/treating rubber belts stay away from alcohol since it dries out rubber. Use Rubber Renue by MG Chemicals.

Phono cables?

input capacitance at the iFi MM inputs? (Input stage also adds capacitance. We need to figure out the total capacitance seen by your cartridge.)

Thanks again everyone. A couple of clarifications:

 

I am currently running the phono preamp directly into the CJ which, as someone else stated, is a control amplifier (integrated amp minus any gain stage).  It’s basically an MV-60 with three inputs and a volume control. 
 

I also remove the dust cover for all listening.

 

The cartridge is a Clearaudio Virtuoso - a MM cart that sells for around $1,000. 
 

The iFi does not allow for adjustment to the MM cartridge load and is defaulted to 47k ohms. 
 

I do not have a stylus pressure gauge but followed the setup instructions very carefully and believe it is set at the recommended pressure - certainly within the recommended range. 

Avoid new reissues! Most are cut from digital files and are often poorly mastered and pressed. I search for and buy original pressings made from an all- analog signal chain. They are often cheaper than new reissues! Discogs and eBay are both good sources.

The CJ apparently is a “control” amplifier, aka an integrated amplifier. You definitely should connect the iFi direct to the CJ, only. Leave the Naim out of the vinyl pathway. Now you may be able to ameliorate the ticks and pops by proper loading of your cartridge, which remains unknown to me. It’s also important to know what cables you use from TT to CJ. Cables add capacitance. Capacitance from all sources may be creating a high frequency peak contributing to the ticks and pops issue.

 

Also, just for the heck of it, try listening with the dust cover off the turntable. It’s fine to have the dust cover in place when the turntable is not in use, but I am among the many who think dust covers can cause problems when playing LPs.

Doodle, I’ve scanned this thread to find out what MM cartridge you’re using. I don’t find that info. Can you supply it? Also does the Zen provide adjustments for MM gain, and loading of the cartridge? Incorrect loading can exacerbate ticks and pops. Meanwhile don’t spend money; you may not need to. Also, meticulous alignment or re-alignment is very unlikely to help unless you really botched the job to begin with. And there’s no need to run out and buy a US cleaner, either.

Does the Naim impose an ADA conversion on the phono signal? If so that can’t be helping as suggested by your own result connecting the iFi direct to the amplifier (?, or whatever that CJ device is)

Post removed 

The iFi Zen is decent at its price point, and I strongly doubt it’s making some LPs sound bad but not other LPs. The belt squeak seems like an unrelated issue, as you don’t complain of any symptoms associated with speed irregularities.

 

Call your dealer and have them help you. That’s what they get paid for. I don’t think the problem is with your equipment. Dealers get a nice margin and part of that goes to customer service after the sale. Use what you paid for.

As an example, I recently purchased a phono preamp from Gene Rubin Audio. I was having an issue with noise, so I emailed Gene, who contacted the distributor and I would say within an hour, the distributor wrote back with a detailed description of how to address the issue. Problem solved. I have no doubt your dealer would do the same for you.

Thanks for all of the great advice!!

The belt is brand new and clean as can be, but I will try the alcohol trick and, failing that, either swap out the belt to see if it persist or see if I can locate a product that might aid in "grip".  I have tried giving the platter a little spin before turning on the motor, but I really need the extra hand to stabilize the motor while pressing the power button because, for good or for bad, the motor sits freely on the cabinet below the plinth for isolation purposes, but it moves very easily and will inevitably wind up touching the plinth if I don't hold it in place.  Annoying, I know.

I do have a dust cover - I paid a premium for Uncle Kevin's museum-quality clear vue dust cover.  I have to say, however, that it's truly stunning.  The green edge looks like real glass and it's an impressive piece of...well....plastic!

I'll check the alignment again and reset the anti-skate.  I don't have a record cleaning "system".  For right now, I'm just using a record doctor brush.  All of my vinyl is new, so it should be relatively clean, just need to keep the dust off.  But it sounds like I'm going to also need to invest in an ultrasonic cleaner?  I'll read through the forums and see what you all think of these $400-500 jobbies coming out of China.  

I've always loved Audio Research and have owned several of their amps and preamps, so it stands to reason that one of their phono stages would be equally impressive. 

I guess I just figured that something like the iFi or MoFi (sub $500) phono preamps would sound "good" if not amazing.  It just makes me wonder what some of these YouTube reviewers actually hear - because as many of you know, the iFi received RAVE reviews and was touted as a true "giant killer".  But alas....it seems that, perhaps, you get what you pay for after all.  I should have known better.  

My path forward will be to double-check my cartridge alignment, see if I can rectify the belt slippage by swapping it out, and start with replacing the phono preamp with something appreciably better - perhaps ARC.  I'll look into the ASR Mini Basis Exclusive.  Any other phono preamp recommendations? 

I was reading about your nice table. The review mentioned that the cartridge should be checked for alignment with an alignment template to be certain that it's correct. It also suggested that the cartridge be as forward as possible. If the cartridge is realigned, that may resolve your distortion issue. I'd also reset your ant skate as this could cause distortion as well. I would do all of this prior to calling your dealer or Marantz.

I use an Origin Live Belt for my modified Thorens and it is better sounding than the Thoren belt. As far as belt slippage, if you have around 60% alcohol, I'd clean off the belt and see if that eliminates the slipping. Don't play warped records without a heavy record weight but a heavy weight would probably play hell with your motor. 

I have an ASR Mini Basis Exclusive phono stage which punches well above its weight class. I'd recommend finding something along these lines on the used market. That is if you're unhappy with your current phono amp. The Clearaudio cartridge should be good enough. I believe Clearaudio cartridges are made by Audio Technica.

I can’t help with the turntable, but that is a really cheap phono stage. A really high quality phono stage is really critical. My first Phonostage was a really highly rated $200 one, it was junk. Until I got to the $2,000 category it didn’t sound anything but tinny and thin.

 

While my turntables, cartridges and phono stages have gotten better over the years, my analog rige did not sound great until I got a Audio Research phono stage… like forty years ago. I would poke around for a used Audio Research PH 3 or higher… 3se, 5, 6, 7, 8… the PH8 I think was the most cost amazing phono stage. 

1. Give it a helping hand. No big deal.

Assume you've ensured there's no oily contamination on the belt, the pulley, or platter. Ensure turntable is level in both planes. What is the turntable mounted on? 

Contact the vendor or Marantz about the belt squeak if it’s bothersome. It might go away as the player breaks in. Mine sometimes squeaks on startup, I don’t turn it off to change a LP so it’s one squeak per listening session, no big deal.
Your system deserves a much better phono stage than the $150 entry level Zen. I’d look for something in the $1k range, about half the cost of your TT/cart. Something with a decent power supply, no wall wart. I haven’t been paying attention to amps in that range so I can’t recommend any. Some vendors give a trial period, something to consider.
About the record noise, some are just poor quality and some labels are best avoided. A better phono stage can reduce some or maybe most of it.

It's impossible to know, for sure, what's going on without having a close look and listen to your audio system, as well as the records you describe.  That being said, the TT you have is top notch for its price point.  I did some serious seat-time with one 3 or 4 years ago and there was no start-up squeak or slipping.  On that front, I would make sure the bearing is adequately greased or lubricated, the floating motor is properly positioned and everything is accurately leveled.  If the squeaking and/or slipping continues, I would contact Marantz for troubleshooting.  Defective motor?  Defective belt?  Hard to say!  When not playing records, I would recommend taking the belt off to maintain its tensile strength and increase lifespan.  Start-up squeak wouldn't bother me if everything else works the way it should.  Some TT's, including high-end TT's, do that.  This one shouldn't.  With regard to belt slippage, I'd make sure the side of that acrylic platter is clean and does not have any kind of contaminant on it interfering with the belt's ability to grip.  There is a product you can coat the belt with to increase its stickiness, but you shouldn't be getting belt-slippage in the first place.

With regard to the varying conditions of the records you describe, I would say stop buying or getting them from wherever the heck you are getting them from!  That's deplorable!  Ultrasonic cleaning or any kind of effective record cleaning is, certainly, a great recommendation.  Getting a dust cover for your turntable, if you don't already have one, would be a good idea, as well.  I know some vinyl heads wouldn't dream of spinning records with a dust cover in place but I'm not one of them.  There is always dust in the air and that doesn't belong on records.  Using a good quality carbon fiber brush before play would be another good idea, as well as keeping your stylus clean.

There are a thousand other possible reasons for the sound quality variations but it's impossible to know without seeing and hearing your system.

1. Don’t know yours but my platter is so heavy I wrecked the belt within a year. I got a reflex clamp and give it a twist before powering up. Still on the second one 35 years later. Belts are cheap. 2 now are less $$ than 1 then.

2. LP pressing quality varies insanely. I’ve bought many records that are quieter than new, sealed ones. All you CAN do is UltraSonically clean them before first play and cross your fingers. Then try another if you hope for better. OR spend up for Hot Platters.