Objekt and Jose Alberto Luna, the production manager from smartbar, share their personal guidelines.
You can find Hertz's A DJ's guide to turntable isolation here, and Luna's step-by-step process for quality controlling turntables below.
Jose Luna's quality control process
While I don't feel it's absolutely necessary to bust out a multimeter/voltmeter/Fozgometer before every gig, there is definitely a quality control process that everyone should take prior to placing turntables in front of an artist.
Isolating the turntable means reducing or eliminating vibrations or resonances that can be picked up by the turntable's body, tonearm or cantilever/stylus. These vibrations fall into three categories: structural, airborne or self-generated. Each has to be addressed independently.
Structural isolation refers to sound waves travelling through physical mediums, the surface upon which the turntable rests and its base. If you have turntables on a plastic folding table with subwoofers in close proximity to the table, the lack of isolation will cause the stylus to jump out of the groove with every bass drum/sub-bass hit, or cause a constant audible hum/rumble. There are plenty of aftermarket products and creative DIY workarounds for this issue. The most ubiquitous tools for isolation are: vibrapods; isolation mats/platforms; domes/cones/spikes for placing under the turntables feet; and vibration-reducing feet that screw into the turntable body itself.
At smartbar we apply DIY tactics as well as some aftermarket products to address this, and even though the table in our booth is a custom onsite build with isolation in mind, we still practice redundancy concerning isolation. Underneath our turntables you will find Isonoe Isolation System feet standing on top of concrete patio/paving slabs, on top of four well-placed and gaff-taped squash balls. We also have a few sets of vibrapods on hand just in case.
Airborne vibration refers to the sound waves being produced by the speakers travelling through the air and creating vibration or resonance within the turntable body, circuit board, tonearm or at the cantilever/stylus point. This problem will present itself to the listener as mild distortion during playback, or feedback at a higher pitch than that of structural vibration. The biggest factor in creating/reducing airborne vibration is speaker and turntable placement. Adjusting where your turntables are or moving the speakers a bit further away can reduce airborne vibration and the feedback it generates. It could also be that the sound pressure level is too high near the turntables, but good luck telling a DJ to turn down their booth monitors.
Self-generated vibration occurs within the turntable itself and can be caused by the turntable's motor or belt. The motor in the Technics SL-1200 series is magnetic, which translates to no wear on the physical parts and very low self-generated vibration. This design, coupled with dampening in the turntable's body and the motor's high torque and low wow and flutter levels, is what made it an industry standard since its introduction to the market in 1972.
It's the attention paid to the design and construction of the turntables motor and body that really defines most direct drive turntables made for DJing. Many higher-end audiophile turntables will feature a motor that is completely independent of the turntable body. The energy generated from the motor will be passed along by a belt or band. While this is great for high fidelity playback, belt drive turntables do not have the torque required for scratching and cueing records. Don't even ask about a pitch fader; you're lucky if you get three speeds (33 1/3, 45, 78) in this realm.
Making sure that your turntables are level is very important to avoid tracking errors and minimising fluttering during playback. If the left side of your turntable is an inch higher than the right side, the stylus and tonearm will literally be fighting an uphill battle as it tracks the grooves. This can lead to compromised channel balance, slight distortion and uneven wear on the grooves of the record. There are laser levels available for purchase for establishing pinpoint accuracy, but you'll find most industry professionals using bullseye/bubble levels. While it's most important to have the turntables be level at the point where the stylus tracks the record, you will also want to check the platter at a few other points.
Imagine that where the stylus tracks the record is the bottom right of an X and proceed to make sure the other three arms of the X are also level. Place the bullseye/bubble level on the slipmat close to where the stylus would initially drop and again towards where the innermost grooves would be. Repeat this process for each arm of the X. You can shim where needed underneath the turntable's feet to get as close to level as possible. If you do not have access to a bullseye/bubble level, any six to 12-inch spirit level will work in a pinch. While you will get close to level, you don't achieve true level unless your name is Rick Sanchez.
Visual motor check
Again, we are foregoing the use of any electrical measuring meters here, as many people may not have access to them or do not know how to properly read/use them.
Pretty much every turntable that is made for DJing has visual components on the unit itself to check the zero point and +/- adjustment of the pitch fader. The components are normally one small light (strobe) and a series of strobe calibration patterns (dots/lines/bars) along the side of the platter. On the Technics SL-1200, the strobe is the red light underneath the on/off switch, and the calibration pattern is the four lines of dots on the side of the platter. When the pitch fader is at zero, the largest dot on the side of the platter will hold still during rotation. Once you have confirmed that the zero point is in fact the zero point, you can begin to move the pitch fader towards the +8 peak. As you move the fader closer to you, the largest set of dots should begin to move forward. The rate of rotation should increase smoothly in conjunction to with how you move the fader. If you notice a second zero point, an elongated zero point, a sudden jump or decrease in platter rotation speed, or see the largest strobe dot appear to move in reverse, then there is a motor issue that needs to be addressed, and this turntable should not be used.
If you do not observe any issues and see a smooth increase in platter rotation speed in accordance with your adjustment of the pitch fader all the way to +8, then congratulations are in order. You now get to repeat this process three more times: once at 33 1/3 RPM while decreasing the speed, once at 45 RPM increasing the speed, and finally again at 45 RPM decreasing the speed. If you have not seen anything other than smooth increases/decreases in speed at both RPMs, then the turntable has passed this check.
Sound check (signal and isolation)
With a record on the platter, plug the turntable's RCA cables into the phono section of a DJ mixer. Keeping the volume down, connect a fully-assembled headshell, cartridge and stylus to the receiving end of the tonearm. Turn on the turntable, press the start button and drop the needle on the rotating record. Even with the channel volume down, you should see audio information registering on its meter. Slowly turn up the channel volume and listen attentively for any issues in audio quality, tonal balance and channel balance and try to resolve them. We are basically doing an initial test here to make sure the physical information on the record is being converted into audio. Channel balance issues can be further addressed with azimuth, which we will get to. Right now we want to make sure everything is functioning. You'd hate to go through all aspects of set up only to find out that your tonearm wires or RCAs aren't working properly.
Once you have established that the turntable is sending audio, turn on the house speakers and then turn up the monitors and the house. Make sure your turntable is properly isolated and if there isn't any feedback present, move on. We will now begin to dial in the turntables for optimal sonic quality and performance.
Overhang and cartridge alignment
If you hold the headshell over the spindle in the centre of the platter, you'll see that the stylus reaches past the spindle. The distance the stylus goes past the spindle is called "overhang." Setting this properly is crucial to proper tracking and minimising distortion in the higher frequencies. The correct overhang is determined by the turntable manufacturer, and the standard for Technics is 14mm. On a Technics SL-1200, the distance from the back washer of the headshell/cartridge to the stylus should be 52mm. There are some affordable and easy-to-use tools out there that help you to set the overhang very quickly. You can get overhang gauges at most record stores or online retailers—having one will greatly simplify your turntable set up. It is hands down the fastest and easiest way to measure and set the proper overhang.
If you don't have access to an overhang gauge, a little more work will be in order. If you have a cartridge rather than a headshell mounted system, you don't need to check overhang as these cartridges come set up from the factory. This would be the case with Shure Whitelabel or Ortofon Concorde series carts. The other way to set overhang is by using a cartridge alignment protractor. There are many protractors available but the most common are the Baerwald, Loefgran and Stevenson. There are others that are manufacturer specific. You can also print protractors from various websites but it's crucial that they're printed to the correct scale. Since these protractors also help us properly align the cartridge body, we will be setting both overhang and alignment simultaneously. The protractor will have two null points, which are perfectly tangential to the grooves. You want to make sure that your stylus drops in the centre of both these null points. If this isn't happening, the overhang is too long or too short, which means you'll need to loosen the mounting hardware that holds the cartridge body onto the headshell and adjust its position in the headshell until the stylus sits in the centre of both null points
With the overhang set and the screws connecting the cartridge to the headshell kept slightly loose, you can align the cartridge. A properly aligned stylus and cartridge body ensures playback clarity, creates stereo balance and stops premature wear on your records. Setting the alignment is fairly simple. There's a grid on the protractor surrounding the two null points mentioned earlier. Align the front and sides of the cartridge body to the lines on the grid, while also paying attention to the orientation of the stylus and cantilever. You may need to twist the cartridge a bit in the headshell to achieve the best alignment to the grid. You will want to check on the alignment by looking down on it from above. Once aligned as flush to the grid as possible, the cartridge may not be parallel to the headshell—this is fine. Having set the overhang and the cartridge alignment properly, you may now very carefully tighten the mounting hardware. Recheck the alignment and overhang once you have tightened the screws as it may have shifted in this process. If you check the null point and the grid after tightening the hardware and have no issues, then these have been set properly.
Vertical Tracking Angle (VTA)
The correct vertical tracking angle is important to achieving the best possible sound and reducing wear to your records and stylus. We are trying to get the tonearm parallel to the platter so that the stylus tracks the record at the same angle that the cutting head was at when the master plate was made. The cutting head used to be at a 15 degree angle but the introduction of stereo records changed it to 20. Your stylus will already be set to 20 degrees but the wrong VTA will alter that. There's a large ring with a number gauge and the words "height adj" at the base of the tonearm. This raises and lowers the tonearm, which is how we set out VTA.
Again, in order to keep the stylus at the 20-degree angle, we need to make the tonearm parallel to the platter. Rotate the turntable so that the tonearm is close to you. Place a medium thickness record on the platter, drop the stylus on the record and bring your eyes down to the level of the tonearm and platter to inspect the angle of the tonearm in relation to the record. If the tonearm appears to angle downwards towards the stylus, then the VTA is too high. This will compromise audio quality and produce tracking errors. Adjust the height of the tonearm by moving the height adjust dial in the needed direction. You will need to check again that the tonearm is parallel to the platter.
The next step is to make sure the height of the tonearm is equal at the cartridge end and the base of the tonearm. You can do this by placing a ruler on the plinth and making sure the height of each side is equal. Use the height adjust dial to get the measurements as close together as possible. Once you these two measurements are equal or very close, you have established the proper VTA.
Vertical Tracking Force (VTF)
Vertical tracking force refers to the amount of weight applied to the stylus from the counterweight at the back of the tonearm. This force helps align the cartridge's internal generator assembly. If the tracking force is too light, you'll lose bass frequencies. Too heavy and you'll overload the suspension. Both will affect playback and performance, plus too little force will generate more wear on your records over time. The correct VTF is determined by your cartridge/headshell manufacturer. You'll find the correct weight in the manual, which usually falls between two and three grams. Otherwise the information is readily available on the internet and a quick Google search should have you on your way.
The next step is to balance the cartridge. This is done by holding the tonearm over the platter and decreasing the counter weight until the tonearm begins to float above the record. You want this to be as close to parallel as possible. Once the tonearm is floating, place the tonearm in its rest, lock it into place and set the dial on the front of the counterweight to zero. Be careful to avoid adjusting the weight itself.
The suggested tracking force of a Shure M44-7 is 1.5 to 3 grams. Turn the weight to somewhere in the middle, let's say 2.3 grams. Drop the needle on the record and begin to play it while listening attentively. Is there bass missing? Are you hearing distortion in the high frequencies? Can you back cue the record without it jumping the groove? If any of these issues occur, your tracking force is too low and you need to add a little bit more weight. It's important to remember that a low tracking force can wear out your records and compromise sound quality. Sometimes the counterweights are a little inaccurate but a digital stylus force gauge can get you a perfectly calibrated VTF. However, it's crucial to rely on your ears.
Azimuth refers to the angle of the stylus relative to the grooves of the record. Ideally the stylus should be perpendicular to the grooves. An orientation other than 90 degrees will affect audio quality, stereo image and shorten the life of the stylus. People often make the mistake of paying more attention to the cartridge body and not the stylus when adjusting azimuth. There is a dedicated piece of equipment to measure and optimise azimuth (Fozgometers). But for everyone's sake, we will move forward as if there isn't one available. There usually isn't.
Some turntables require dismantling the tonearm to adjust azimuth. Fortunately, Technics SL-1200s do not fall in that category. To adjust azimuth, start by locking the tonearm into place and removing the headshell/cartridge. Once removed, you will see two slots where the cartridge locks into the tonearm. Using anything with a true right angle––speed square, protractor, ruler, credit card––place the object on the turntable's plinth and line it up with the two slots at the receiving end of the tonearm. The slots at the end of the tonearm end should be at a 90 degree angle to your bank card or ruler, although a slight counter clockwise lean is OK. If the angle is off, loosen the two screws hiding under the tonearm and behind the cartridge/headshell. The screws are size 0 Phillips heads; you will need an L-shaped arm to reach the screws. With the L-shaped arm and Phillips head attachment, gently loosen the two screws. Now adjust the receiving end of the tonearm until the slots line up with the right angle. Tighten the screws back up and connect the headshell/cartridge to the tonearm.
You will now need an older mono record or a stereo test vinyl to continue the azimuth check. With the record on the platter, place the stylus on the grooves of the record and look at it head-on. You should be able to see how the stylus is oriented in the groove. We're looking to get as close to perpendicular as possible. If you can see that that is not the case, lock the tone arm, remove the headshell/cartridge and repeat the previous process until you have achieved the 90 degree relationship between stylus and groove. Once you have visually checked this you can move on to the audio check.
Place the mono recording or stereo test record on the platter and begin to play it. The mono record has an equal left/right channel balance. By panning the output on the DJ mixer and listening attentively for discrepancies in channel balance volume, you can determine if the azimuth is off. If the right channel is louder than the left then your azimuth needs to be adjusted further. If you have a stereo test record, play the left or right test track. Most of these records will announce which channel has audio output before they begin to play a test tone. Once the test tone is played, listen for any crosstalk on the channel that is not supposed to be sending an output. If you hear no audio on the opposite channel then you have achieved the proper azimuth. If you hear crosstalk or a volume discrepancy with the mono record, then further adjustments need to be made. If you have a decibel meter available, this is also a good way to put a number on the output of each channel individually as you test them.
Anti-skate might be the easiest part of setting up a turntable. It's usually a one-dial control near the base or pivot of the turntable and it will normally have a printed gauge on it. Anti-skate counters the force created by the rotation of the record and platter, which wants to draw the stylus in towards the centre of the record. The rule of thumb is that you set your anti-skate to the same number/weight as your VTF and adjust accordingly. Anti-skate directly relates to proper tracking, so if you set your anti-skate to the same weight as VTF and are still experiencing tracking errors during playback and backcues, then you need to increase the anti-skate. One test I like to do to check proper tracking and anti-skate is to use the blank side of a one-sided record as a gauge for tracking. Place the stylus on the blank record and begin to play it. If the stylus is drawn inward, then adjust the anti-skate until the movement inward has disappeared completely and the stylus is holding steady. Once the stylus is tracking the blank record your anti-skate is properly set and you can move on.
Sounds and scratch check
OK. Wow, we're at the end. Everything should be in order at this point and now we just want to make sure we are sounding as clear as possible and that the records are tracking properly. Grab a record that you are very familiar with, preferably one with a decent dynamic range and maybe some noticeable panning going on. Play it and listen very attentively. Close your eyes and really zone in on what you're hearing. Are the higher frequencies bright but not distorting? Is the mid-range clear? Are the bass frequencies present in the way that you know them to be on this particular record? Are the right and left channels balanced and can you tell when an element of the track is panned in a certain direction? If you answered yes to all these questions, then your turntable is good to go.
Now grab another record, preferably a battle tool or acapella, and go into your best fake DMC championship routine. Don't worry about the techniques being applied right now—you just want to make sure that the turntable could perform properly for someone who does in fact know how to scratch. If you can do your best impersonation of DJ Swamp in '96 without any tracking errors then you have set up your turntable properly and it is ready for any performance.