This month’s Studio SOS challenge was to help a college music department get a better recorded drum sound.
This month’s Studio SOS saw us in the old Roman city of Cirencester, at the local sixth‑form college where instructor Charlie Baxter, accompanied by the Head of Music Rob Faulkner, asked us to help in getting a decent recorded sound from their somewhat battered Mapex drum kit (with Pearl snare drum). The courses they run comprise A‑Level Music Technology in addition to a Level 3 vocational course in Music Performance.
The kit was set up in a small room with some rather sporadic DIY acoustic treatment, and the first thing that Hugh and I noticed was that pretty much all the wall surfaces were covered in carpet, though there were also some squares of fairly thin acoustic foam applied in places along with two large mineral‑wool panels leaned against the walls to help with bass trapping. A couple more foam panels were glued to the ceiling to help limit the amount of reflected sound getting into the overhead mics, but it was all a bit haphazard! This left very little in the way of reflective surfaces other than the exposed ceiling, so we suggested that hanging a few MDF or hardboard panels along the walls might bring a bit more life back to the room, which predictably enough sounded dead and somewhat boxy due to the carpet taking away all the highs but doing little to tame the mids.
Charlie explained that when recording drum kits, the kick drum was presenting the biggest problem. This was set up with a few pieces of foam inside, weighed down with a paint tin full of sand to aid in damping it. The front head had a small hole cut into it but didn’t leave much leeway for adjusting the mic position. The studio had an AKG D112 for recording the kick, augmented by a sub‑kick mic (a speaker cone wired as a microphone), but the recorded results were dull and muddy, lacking any serious low‑end weight or high‑end slap.
Jam Out The Kicks
A good‑sounding drum recording starts with a well‑sorted drum kit, so I decided to check out the kick drum more closely. It was fitted with decent Aquarian heads but the internal damping wasn’t doing a very good job, and I felt the batter head was too tight, resulting in a tubby sound. That’s what happens when you let students loose adjusting drum kits! I quickly spotted that one of the batter‑head tension lug bolts was missing, too, so it was impossible to get an even head tension. Also, the wing bolt that holds the pedal to the drum rim was missing, but Charlie quickly found a replacement pedal while I ‘borrowed’ a lug from the front head to use in tensioning the batter head properly, since it made sense to remove the front head to sort out the damping anyway. While the head was off we could make a test recording to see how the sound changed between having two heads and one.
Having removed the bits of foam from inside the drum, I made a new damper from a large square of fabric folded and then rolled up, leaving around six inches unrolled. A little gaffer tape held the rolled section tight. The rolled section was pushed against the lower inside of the batter head, and the tin of sand placed on the unrolled section to stop it moving around.
Batter Of Fact
To tune the batter head I used a simple technique often employed when fitting new heads. The first step is to slacken off all the lugs and then to press hard on the centre of the head to ensure that it is properly stretched and seated. Next, using fingers only, the lugs are tightened until they are just ‘finger tight’, and this is a good starting point. Using this method, only slight adjustments were needed to even up the pitch when tapping around the edges of the drum head. Setting the kick drum up this way gave it a lower pitch than it originally had, and it now sounded very usable when recorded with the D112 positioned just inside the shell, roughly halfway between the centre of the drum and edge.
Having recorded a couple of minutes of playing, we replaced the front head, tensioning it in a similar way — for now ignoring the missing tensioner that we’d moved to the batter head. With the D112 just poking into the hole we made another test recording which produced a decent sound but with a slightly different, more resonant character. Next, I turned the beater head from the felt side to the solid plastic side and we recorded that too.
All three sounds were very usable but, of the three, Charlie preferred the head‑on, plastic beater rendition, while Hugh and I both preferred the more old‑school rock sound with the front head taken off. However, if they intended to record with the front head on I suggested that the hole should be enlarged (to perhaps the size of a side‑plate) to allow a little more leeway in mic placement, but otherwise the setup would work OK.
With the kick drum sorted, we turned our attention to the rest of the kit, starting with tweaking the tom tuning to get the pitch even all the way around the heads. I also applied some additional gaffer tape and tissue pad damping to both the upper and lower tom heads of the floor tom, with the top head damping right at the edge. This took off the excessive ring without killing the sound. We checked the tom sound using a Rode NT2000 in cardioid mode positioned as high as possible, right under the foam ceiling tiles to minimise ceiling reflections. This confirmed that the toms sounded better tuned and with a more even decay time.
While I was fettling the kit, Hugh was in the control room listening and making some interesting discoveries about the setup of the Allen & Heath GS‑R24 console that was being used as a DAW front end for Pro Tools, which was running on a Mac Pro ‘dustbin’. The two studio mics (the AKG D112 on the kick drum and the Rode NT2000 overhead) were plugged into the first two channels of the GS‑R24 console, and from there went into the Pro Tools system, with the replay from Pro Tools coming back on channels 15‑16.
While I was experimenting with the kick drum, Hugh played around with the desk EQ, scooping the lower mid and boosting the highs in the usual way, but on playing the recording back it became apparent that the EQ hadn’t been recorded. That wasn’t a problem since the EQ could be done in the DAW anyway, but it became more of an issue later when Charlie suggested patching in a Warm Audio WA76 compressor. With a bit or furtling behind the desk, Charlie managed to patch the compressor into the kick drum channel, but again its processing effect wasn’t recorded into Pro Tools.
Clearly, the direct output feeding the DAW was both pre EQ and insert, but thankfully A&H have thoughtfully included four buttons (labelled A, B, C and D) at the bottom of each channel strip to reconfigure how the DAW interfaces with the channel (for both recording and playback). By default, the record feed is derived straight after the preamp, but by pressing button A the DAW gets the signal after the insert point and EQ: problem solved!
The only slightly odd issue was that to get the WA76 compressor working sensibly we had to dial its input control pretty high, but turn the output control almost right off. That would suggest the desk’s insert point was operating at a much lower signal level than the WA76 expected, and the specifications for the desk stated the insert point worked at a nominal 0dBu operating level while the WA76 operates at a nominal +4dBu. The level discrepancy seemed rather greater than those numbers implied but, although we didn’t have time to get to the bottom of it, we managed to get it to work well enough nevertheless.
After a surprisingly good lunch from the college canteen, we moved to the music suite where several Macs were set up running Logic Pro. I suggested that we use Logic’s Match EQ plug‑in to examine the difference between our kick recordings (made both before and after treatment) and one of the Logic drum kit kicks that Charlie liked the sound of. We looked at the kick from the So‑Cal kit, loading that as the reference sound, with our latest kick recording as the ‘current’ sound. This comparison showed quite clearly that the So‑Cal kit had been given a significant EQ dip centred at around 300Hz and quite a bit of shelving high‑frequency boost above 2kHz. Even using matching EQ, the sound of the two kicks was still noticeably different, as EQ can’t compensate for the different decay times of the different harmonics and partials that make up the reference sound, but it did add a welcome degree of clarity and punch while taming the mid‑range mud. As the So‑Cal kick is very bright‑sounding in the upper mids, we also brought in Logic’s harmonic Exciter plug‑in set to a frequency of around 1.4kHz, and used that to synthesize some new highs, which really added to the clarity and click of the recorded kick sound.
We then went on to explore how very short‑ambience reverbs can change the sound of a kick drum quite radically but without the result being washy. One of Logic’s bright drum‑room impulse responses with the envelope pulled back to produce a short, gated ambience worked particularly well in adding life to the sound.
I explained to Charlie that I have, in the past, used a mechanical means of adding click to a kick drum sound by using a piece of plastic, such as an old credit card, fixed to the batter head where the beater hits. I used a piece of double‑sided foam tape, 2‑3 mm in thickness, to fix just the top edge of the card to the head so that it hangs down parallel to, but not quite touching, the head. This seems to produce a better slap. Charlie said he’d definitely try that.
It’s always good to meet people who are keen to experiment and both Charlie and Rob seemed keen to try out everything we’d suggested. Fortunately the room fix needed only a few inexpensive plywood or MDF panels to sort out and the drum kit was mainly a matter of tuning. Now where did that missing tuning lug get to?
“Thanks to Paul and Hugh for coming in and sorting out our drum sound, particularly for fixing our ‘soggy’ kick! We both learnt a lot during the day regarding drum tuning and how a few tweaks to the kit and the room acoustics can make a big difference to the finished recording. We now have plans to laminate the floor over the summer and think this will bring some life back to the room.
"We are particularly pleased that we now have a good reference drum recording with which to judge our future efforts by, and this will certainly improve our A‑Level Music Technology students’ recordings in time for their assessed recorded course work next year. In addition this will undoubtedly save time processing and only reinforces the point of capturing the best possible sound at source rather than fixing it in the mix! Whilst on the subject of mixing, Paul’s processing tips were much appreciated and have resulted in the purchase of an Aural Exciter plug‑in to play with!”