The AKG C 480 B ULS in practice

[Bob Moose]

Hello,

I have finally tried two AKG C 480 B ULS microphones, with the CK 62 omnidirectional capsule. For this, I had to buy them, but it was still possible to return them in case of problem.

The C 480 preamplifiers and capsules are not available as a factory matched set, but some people told me that such good microphones do not have to be matched.
That said, the shopkeeper told me that he could manage to get devices featuring consecutive serial numbers, which is supposed to help getting microphones that match better.

When the microphones arrived, the shopkeeper told me that only the preamplifiers could have been serial-number-matched, as there is no apparent serial number on the boxes that contains the capsules.

When I opened the 4 boxes, I remarked that

- for one of the preamplifiers the serial number was the same on the box and on the device, while for the other one the numbers were completely different; actually the serial numbers of the preamplifiers were totally different

- the capsules had a serial number but you could not see it from the box; and actually there was a difference of 2 between both numbers

More interestingly, both capsules were sold with a paper that shows the frequency curve and the sensitivity (measured by AKG in the factory). To sum up things:

- one of the capsule ("number one") had a sensitivity of 14mV/Pa; the frequency curve was almost flat (0dB) from 40Hz to 5000Hz, and there was a HF boost between 5kHz and 20kHz, the maximum boost being +5dB at 8.5kHz

- the other capsule ("number two") had a sensitivity of 18mV/Pa; the sensitivity curve was equal to about -2dB from 40Hz to 250Hz, flat (0dB) between 250Hz and 5kHz, and the HF boost was somehow similar as the one of the other capsule

- on the user manual, the sensitivity is 20mV/Pa; the frequency curve is 0dB-flat between 30Hz and 5000Hz and the more parabolic-looking HF boost is only +2dB (at 10kHz, not 8.5).

I imagined that I could perhaps not hear any difference but actually it was not the case when recording. As I had not been able to avoid seeing the curves before recording, I sent the recordings to some other people, only asking them if they could hear a difference between the two files (and I didn't tell them anything more). Most of them agreed that one of the track had less low frequencies, or more high frequencies / more agressivity, which confirms that the supplied AKG curves should be honest.

Omnidirectional (pressure) microphones are known for great bass reproduction (and no proximity effect). Using two omnidirectional microphones for spaced recordings helps getting a great spatial rendering (while the localisation is quite inaccurate) with especially good and "natural" sounding low frequencies compared to the recording techniques that use only directional microphones.

Therefore, as I intended to use these microphones for both 2-track and 1-track recordings I decided to take these microphones back to the shop.

One of them (labeled "number one" above) is truly good, and if the other one was the same I would have kept both.

All the best,
-j

[Ariosto]

I'm sorry to read your review Bob, as I had this mic at the top of my shortlist, and had more or less decided on it.

Oh well, back to square one!!

[Bob Moose]

Oh well, back to square one!!

Exactly.

But if you are lucky and get closer matched microphones, or if you have enough time for calibrating the microphones yourself using some IR recordings one time and applying a few convolution operations after each recording, or if you simply want to use these microphones as separated monophonic microphones, then they may be okay.

That said, while I don't have anything particular against AKG, I will have to be honest and say that the microphone "number one" (see my original post) sounds really better than "number two". "Number one" is quite neutral and natural, big sounding but not too much overhyped, perhaps with slightly too much HF boost for me but using an EQ would help correcting it easily. "Number 2" sounds weaker, less full bodied, and more aggressive. At that price, I think the difference is too important (for example, about 7dB at 20Hz!). To put it differently, I would say that the microphone "number one" is correctly priced and could be a practical cheap alternative to DPA or Sennheiser MKH microphones, while the the other one is simply not worth it.

Regards,
-j

[Bob Bickerton]

That's unfortunate Bob.

I'm not familiar with the AKGs but at the risk of covering 'old ground' I purchased a matched pair of KM183s and I think they're the bees knees!

Haven't noticed any differences between them and I feel confident on using them as a stereo pair for chamber music, piano and outriggers on orchestral material (not that I do heaps of this work, but these are the applications I've used them for).

Bob

[Bob Moose]

Yes, the KM 183 is a good alternative

the Sennheiser MKH 20 should be even better for what I want to do

and how about the OktavaMod MK-012?

As you can see, I will need to have some reflection...

[JeanMarie]

there are not a lot of omni SDC sold in matched pair in the middle range. I would have recommended the Beyer MC-910 but I see nowhere matched pair. And for sure I am interested by these but I will wait that Beyer sell pairs (like the MC-930 pairs) before buying them.

[Bob Moose]

there are not a lot of omni SDC sold in matched pair in the middle range. I would have recommended the Beyer MC-910 but I see nowhere matched pair. And for sure I am interested by these but I will wait that Beyer sell pairs (like the MC-930 pairs) before buying them.

Indeed the Beyer MC-910 looks great (and I always like Beyer microphones), but it's noisier than the MC-930 and as you said it's currently not available as a matched pair, which looks dangerous in this price range.

Cheers
-j

[Jeraldo]

Using two omnidirectional microphones for spaced recordings helps getting a great spatial rendering (while the localisation is quite inaccurate)

The problem with general statements that are true-and yours is-is that they are often difficult to apply, as each microphone and situation is unique.

Localization might be-or not- more precise with directional mic's, but whether it's accurate or not is another matter entirely. In fact, many people would disagree on such basic issues as where to place an ORTF or omni array, not to mention agreement or not on basic directional mic arrays (ORTF, NOS, MS, Blumlein, Stereo 180, SoundField). Then there is the issue with pairs of directional mic's returning location cues that vary by frequency-depending on how the mic is designed and the desired low end response. Omni's upper end vary by frequency as well, and the location cues of the lower end may vary by the distance of a pair, not to mention standing waves in the room. Shuffling used with omnis or directionals is another image option.

To blur the issue a little more, consider the combination of an omni and 8 in MS.

I wish you success if your search for omnis! I suggest you try the Neumanns or Sennheisers mentioned-both excellent but quite different. The Oktavas-which I own and like-will never be paragons of consistency or reliability.

[Bob Moose]

Thanks for your answer Jeraldo.

The problem with general statements that are true-and yours is-is that they are often difficult to apply, as each microphone and situation is unique.

Yes indeed. On the one hand, this statement is written in many serious documents, and I often experienced it in practice. On the other hand, I think it depends a lot more on contextual factors, especially the room (or outside) acoustics, the instruments and the position of the microphones.

When it comes to spatialisation and immersion (for me, this refers to the fact you really feel like being in the recording place when listening to it through speakers), I often had really good results with spaced omnis. And I usually record below the reverberation radius as I prefer an accurate sound and as I find it more natural during the playback (a normal room usually has some reverb, which adds to the recorded reverb).

But one time, for example, I recorded a short piano track in a very bad sounding room, and the piano was no way better (actually it was advertised as a "recording studio" but only the lady who worked there was interesting). All I had was 2 borrowed Schoeps omni microphones. No matter where I placed the microphones, the sound was not immersive at all and, of course, really bad in any way. More surprisingly, it was not even realistic (both the recording and the room sounded crappy, but they were quite different).

Conversely, I know a place where the sound is always very good; all the recordings I made there are immersive and big sounding, even when recording with spaced AKG SE 300 B cardioid microphones...

Localization might be-or not- more precise with directional mic's, but whether it's accurate or not is another matter entirely.

Actually, as I usually don't care much about localization (I am more interested in overall spatial rendering and sound quality), I admit I never studied this seriously. So the well-known statement about space omnis not producing a clear localisation is not a practical problem for me (when recording for myself).

That said, what you explain about frequency-dependent directivities makes a lot of sense.

To blur the issue a little more, consider the combination of an omni and 8 in MS.

Yes, but this is supposed to be equivalent to 2 cardioid microphones that have an angle of 180 degrees (of course most cardioid microphones are not good enough to do this).

Sometimes, I have recorded to native horizontal B-Format (one omni and 2 figure-of-eight), which is a generalisation of the MS principle, and I really liked the flexibility of this technique, both for 2-track or 4-track applications (I am using a decoding that is technically similar to the one that comes with the Schoeps Double MS system).

Having two omnidirectional and two figure-of-eight matched microphones would be a killer setup for me, but I will consider it much later, as currently only two of my microphone preamplifiers are really good. One advantage of Sennheiser and Neumann (and also Schoeps) is that they make figure-of-eight versions of their SDC microphones, which is not the case of Oktava, AKG, Gefell or even DPA.

Best regards
-j