As I look through turntable specs on various sites (Vinyl Engine, Vintage Technics, the Dual site, etc.) there are usually specs for Rumble, Wow and Flutter, and sometimes Signal-to-Noise (how is that different from Rumble?) These vary greatly and some specs can be astoundly good, at least in theory. One wonders how much difference can actually be heard and how much was sales hype. Some turntables that are well regarded (many Duals come to mind) have worse specs than some of the lowest end Technics. One wonders how some tables ever sold at all if people used specs to decide. How much difference do we hear if rumble varies by as much as eight or ten decibels? How does the choice of cartridge and other variables affect the outcome? Can we trust these figures? What other criteria would matter?

Well, you're not the first to ask that. Other factors such as feedback also affect sound, and no useful measure has been adapted for that, but the effects can certainly be demonstrated. Turntables such as Thorens, Linn Sondek, Ariston and Technics SL-16/17/1800, with suspended plinths, usually were better for feedback supression, so could sound better when used with speakers, but didn't sound better when used with headphones!

In general, rumble and signal to noise ratio are the same, because rumble (from the motor) is the major part of the noise from turntables. Back in the 1970's and 1980's, when vinyl records were the main source of recorded sound, calibrated test records were readily available, so hi-fi tests could be both subjective and objective, whereas these days, they can be only subjective, because test records are no longer available. Usually, the best sounding turntables (eg Linn Sondek, Rega, Ariston, Thorens, better Pioneer/Sony/Technics/JVC/Denon/Luxman models) usually measured well for wow and flutter and rumble, and reviewers usually mentioned when feedback was well supressed, since turning up the volume and tapping near the turntable can test for that. Houses and placement of turntables also affects feedback. External factors such as traffic and trains can also affect rumble.

Ten decibels means that rumble is twice as loud as we hear it, and believe me, you'll hear that! Wow and flutter can also be affected by off-centre records, which is why Nakamichi developed their centreing method for records on their turntables. There was a paper submitted to an Australian electronics journal by an engineering student showing the effect that off-centre records would have on wow and flutter, and arguing that better than 0.1% wow and flutter was really not achievable in the real world because of off-centre records.

Cartridges shouldn't have much influence on either wow and flutter, or rumble - the major factor there is the motor, isolation, and absorbtion. But certainly, over time, research has given us better cartridges, and better sound, due to factors such as better materials, and better electronics. Resonance also affects sound, which is why tonearms can have a major effect on sound with turntables, and why turntable building materials, and weight, and size, are a factor. Turntable manufacturers advertise why their models were better, due to better building materials, motors, and tonearms - all you have to do is do a bit of reading, but I doubt you'll come up with any conclusive answer as to which is the best model, as conditions, and other factors, such as time, and continuous research into sound, mean that things can change quickly!

-Don

This is an interesting question.

Regarding w&f, I've never been annoyed by it even on the idler drive Dual 1009 but have heard w&f on some ently level cassette decks sporting 0.06% WRMS.

On rumble and signal to noise ratio, there is a difference. Consider S/N as the level of noise when the stylus isn't touching the vinyl. Rumble comes to play as soon as there is a mechanical coupling of the stylus to the disk. Of course, if my perception is correct, the S/N ratio is irelevant.

The typical LP I have has such a high level of surface noise that exceeds any rumble specs. A well used LP will deliver 35~45dB of noise level in the silent groove between tracks. A good pressing, unused, can deliver 50~55dB - all that according to casual readings I've taken while digitizing some LPs. And my sound card gives a noise floor well below -105dB.

What can become even worse than the 40dB surface noise is acoustic feedback through the plinth or dust cover. To me, that is one big difference between a bad TT and a good one. That and the motor torque; there is nothing more annoying than a platter slowing down when the LP is cleaned with a brush.

When comparing specs one must know the "weighting" method used as some give higher (better) numbers than others. Weighting is applying some predetermined equalization curve to the raw measurements. This is to factor in the audibility of certain noise components based on the supposed human "hearing curve." The main problem is that all of the weighted methods use different factors to determine their curves and some manufacturers specify whichever method makes their product look the best. The famed AR turntable has -60dB ARLL (CBS and similar to the Japanese JIS) rating, a -65dB DIN-B rating, and a -40dB NAB rating for s/n. You must know the frequencies measured and what is considered "0dB" in order to have the different numbers be meaningful. Or make sure all your comparisons are based on the same weighting curve. And the numbers are meaningless unless the turntable is well maintained and lubed, the cartridge and tonearm aren't mismatched, and mechanical and air-borne feedback is controlled. Any of these can result in audible noise distortion.

On the tapedeck question, assuming the deck is clean and still in spec the wow and/or flutter you're hearing is the fault of the cassette tape housing and not the deck. Cassette deck takeups don't have much torque and the mechanical resistance (friction) that some cassettes develop over time will make itself heard, especially if the tape pancake (that's what they are called) is uneven. This is usually caused by storing the tape after a fast forward or rewind, by a warped cassette housing, or by the lubricating sheets in the housing being dried up. It can, rarely, be caused by stretched tape. Unless the tape is stretched, transferring the tape to a new cassette housing (if you can find one these days) will usually remedy the problem.