D12VR Testing and Comparisons
The AKG D12VR was released a few years ago, and since I started working on the original D12s I've wanted to see how the D12VR performed in comparison. I remember reading somewhere that the D12VR was based on AKG's last NOS D12, but can't find the source now.
Here goes. We'll start with some pictures.
It's worth noting that comparison between the D12VR and a D12 is difficult: any D12 you may find (with the exception of a NOS one I worked on recently) will have been kicked around various stages, studios, etc for the past few decades. The conditions will vary hugely, as will the sound. It might be the case that there's a D12 whose frequency response perfectly matches that of a D12VR, but there will be many more that don't match at all.
Here, I'll be sharing the on-axis frequency response curves of these mics, measured fairly close to the test speaker - a typical position for these mics. These curves aren't the ultimate comparison between these mics: I don't have the anechoic chamber required to pull off full polar data, nor did I investigate the effects of high SPLs: AKG mentions the D12VR uses the transformer from a C414, which might show up some saturation effects at high levels.
All that said, I do find frequency response measurements give a good idea of how a mic will sound, and it's an easy way to compare a few different mics.
Setup & Calibration
This section will explain the test setup, the choice of equipment, and how the equipment was calibrated. It's mostly included for completeness - feel free to skip to the results further down.
The test speaker was a KEF HTS3001SE with the bass reflex port blocked. This is a 4.5" coaxial speaker which is a good approximation of a full-range point-source. This is preferable to using a conventional multi-way speaker, where the woofer and tweeter will be physically separate - those require some distance for the different drivers to acoustically sum, which would mean the room would have much more influence on the measurements. The speaker was facing straight upwards, and I added some foam to cut down on reflections from my desk. I don't know how much difference that will have made, but it's unlikely to have a negative effect.
The mic-to-speaker distance was fixed at 60mm from the front edge of the tweeter waveguide. I decided to keep the mic-to-speaker distance fixed, rather than aligning capsules, as I find this to be more representative of real-world use.
The USB interface is a Behringer UMC404, which is adequate.
To calibrate REW, I used a Beyerdynamic MM1 to measure the frequency response:
Which can then be exported as text, and then imported as a calibration file. With that calibration file in place, I got this:
Which shows the calibration has worked well - only in places with extreme corrections do we have some wiggles, of the order of a couple of dB, and the phase response stays at zero degrees across the range.
The frequency response curves for each mic are presented below, and I included some comparisons which I thought would be particularly pertinent. The images should be self-explanatory, but I'll include some discussion at the end.
First up, the D12VR. I used a boom stand for the rest of the mics, but the hinge on the D12VR wouldn't allow the mic body to tilt towards the speaker properly. As a result, I had to use a gooseneck. The weight of the mic meant the gooseneck was prone to tipping, so I had to hold it for the duration of the test.
Even after going back and looking through the frequency response curves for the D12s I've restored over the past few years, I couldn't find a D12 that matched the D12VR. For now, I consider the D12VR to be a fairly useful mic capable of extended low-frequency pickup, while retaining a fairly "vintage" overall sound. I prefer to implement EQ using the mixing desk rather than relying on the D12VR's switches, although in situations where the mixing desk is very limited, I can imagine the switchable EQ curve being useful.
The D12VR looks and feels like a premium dynamic microphone, and I'll look forward to using it in the future.