A vinyl LP can hold over 40 minutes of music a side. But, the sound quality isn’t good at all.
So, to make a great sounding record I have to be concerned about the playing time, and how the music itself sets the parameters for sound quality. It’s complex, but I will break it down:
There are some guidelines, but it’s important to note that the length of the side, the level, and the bass response are all very closely related.
I have to look at the overall picture, and factor in many details.
Is the music very compressed or limited?
Compression and limiting increase the average level, while lowering the peak level. There are plenty of good reasons to do this for the benefit of the mix. But, taken to the extreme—as is the case for most CD releases—that extra limiting increases the average level so much that I have no choice but to lower the cutting level.
Does the side have long passages of very quiet material?
It’s a numbers game. You can make the louds really loud if you have soft sections where you can conserve space on the disk . So, the more dynamic range you have, the louder the louds sound and the quitter the softs sound. This isn’t ideal for high energy rock or pop, but this helps many other styles of music.
What is the overall bass “impression” of the side?
If it’s a full bass sounding vibe, the record groves are literally deeper and wider, and take up more room. So I have to lower the level to make them fit. And there is “good bass” and “bad bass” with regard to vinyl. Bass that is dead mono and panned center doesn’t use as much space on the disk as “stereo bass”. Keep an eye on the how much bass your mix has on the side. Stereo bass makes the grove cut deeper. And, since deeper is wider (think trigonometry) that means that each groove requires more space.
How bright or aggressive are the high frequencies?
Everything else being equal ,(and we know they aren’t, but for the sake of this discussion…) a record side that has bright vocal moments might not be able to be cut cleanly. Let’s look at…
The Four Limiting Factors
Compression (or, average level)
The higher the average level, the lower the cutting level has to be. On vinyl, the effect of limiting the music is that peaks get lowered, but the average level can not be raised.
Bass level and Stereo placement
If a recording has loads of bass, that will use up space and cause us to lower the level.
High Frequency Content
If a recording has very bright moments, those will cause playback distortion and will cause us to lower the level.
If the side is “long,” then the level will have to be lowered to accommodate the extra grooves.
These four factors are always in play, working with us and against us in making an ideal album side. There are a few corollaries that can be helpful.
On a long side, the level will be lower. This means the high frequency vocal will not be a problem. Conversely, on a short side, bright vocals might not let me raise the cutting level to ideal.
Just a tiny compensation in the bass, either a sub bass roll-off or an elliptical equalizer, can be very effective at helping the cut. They both affect the bass sound quality though, and must be used with good judgement.
Let the dogs run. Don’t use limiters on your mixes and masters for vinyl. The effects of limiters on a vinyl cut are very different then they are on a digital master. Hard to believe, but this is one place where softer is louder. Trust me on this one.
That said, here are your guide lines:
Under 18 minutes, I could cut almost anything. As loud as wanted up to the groove distorting. Full bass, metal, rock—it’s all good.
Between 18-22 minutes, I’m going to depend on a ballad or acoustic song to help with the length. If not, I’ll have to lower the level 2 or 3 db at 22 mins compared to 18 min.
From 22-26 minutes, I might have to lower the level more, or roll off a little bass. This depends on the client’s preference for bass/full/warm sounds vs level.
Over 25 minutes, it’s very likely—even for jazz—that i’ll have to lower the level, maybe clean up the low bass, and maybe more.
I can cut 30 minutes on a side, but the level is down 8db or more from the level I can cut on a 18 minute side. Thats a lot. But, the sound is still good (or can be) even though the record noise becomes more apparent since the music is quieter. If pressed at a high-quality plant with careful consideration, a long side can sound really good.
The “right” answer to the question, How much music fits on a side of a record? comes from a decision made early on in the production. Are you making a nice sounding, good looking keepsake album? Or are you making a high-fi listening experience on vinyl?
If the prime purpose is promotional, don’t worry too much about the level. The result is, you will hear more click and pops, because the audio was cut at a lower level. Put the saved money into great artwork or packaging.
If the purpose is a great sound and vibe, then keep the side below 22 minutes. Maybe 24 for traditional jazz that isn’t very compressed.
I hope this helps you make a great record!