The Telefunken AR-51
Review by Fox Audio Research, Cont'd...
How does it Sound?
When we listened to the AR-51, and I only used my own voice as a reference, I was surprised to hear that there seemed to be a lot less bass in the sound than the mics that we build. I checked my preamp input with another mic and found everything normal, and plugged the AR-51 back in.
No question about it. The mic seemed a little thin on the bottom. Time to break out the Bruel and Kjaer and try an acoustic sweep. About that time I opened up the large white envelope than comes with the AR-51 and guess what I found? I nicely printed response sweep graph of the microphone. Nice touch! Two more points for Telefunken.
If you look at the Telefunken sweep you can see that indeed the microphone has shelf below 200Hz. This has to be by design because is it a very nice shelf. No false advertising here.
When we looked at a sweep of the preamp we see that there is a little low frequency rolloff too, so this shelf is caused partly by the capsule and partly by the internal 12AT7 preamp.
All Sweeps are Not Created Equal
It's pretty clear that our sweep does not match with the TEF sweep above. We are using a Bruel & Kjaer 4135 1/4" reference mic and use it to calibrate our Fuzz Measure software. Not extremely rigorous but we do get repeatable measurements and our Bruel & Kjaer shows flat responses from 70Hz to 25Khz after calibration. (our little Rokit speakers are not reliable below 70Hz) But there is a lot of Black Magic in acoustic testing, so I will not be throwing any stones at Telefunken while I remain safely within the walls of my little glass house.
When we overlayed our response of our FAR m251 mic with our sweep of the AR-51 it confirmed what we heard. We lined up both mics on the 1Khz mark as normal and you can see that the low end is lower than our FAR m251 concept mic. We were shooting for flat low end response in our design.
(To see what a CCDA is click here)
But things became much clearer when we aligned the low frequency response of both mics to 100Hz. Below are exactly the same plots as above, but simply lined up at 100Hz instead of 1Khz.
AR-51 & FAR m251 aliged plots at 100Hz
What you can see clearly this way is that the AR-51 is a microphone that totally pushes the mid range and top for you.
On "close-up-to-the-mic" vocals the built in low frequency shelf also compensates for the proximity effect of a cardiod microphone. This means that when you track a vocal with the AR-51, and you can have the singer up tight to the mic and know that the bass/mid/treble balance of the microphone is probably almost perfect.
This contrasts greatly to the classic ELA m251 which was designed to have flat response at a distance. This was necessary in the days of German broadcasting where an orchestral broadcast could commonly be picked up for Monophonic AM or FM radio using a single microphone!
But when you lean into a real m251 set to cardiod you get bags of bass due to the proximity effect.
So I believe we have uncovered the design goals of the AR-51 and that is modern vocals. (Wow, that took a rocket scientist)
You would never want to use this mic in a stereo pair to record a large choir or orchestra, but you could consider it as a tight mic to support the soloist singer in the choir or the solo cellist in the orchestra.
I have a second opinion from an actual user of the AR-51 who was tracking vocals the week before I "borrowed" the mic from the Long and McQuade store. He said:
"I loved it!"
So the question we have to ask here is:
Can a modded low price mic achieve similar results to Telefunken AR-51?
Yes!
We believe we can modify your APEX 460 or similar mic to very nicely approximate the sound of the AR-51.
What we cannot do is get the talent in your studio all hot and bothered about singing into a Telefunken.
For $1,895 CDN, in Toronto, your singers can be very hot and bothered.
The choice (and the budget) is all yours.
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