Oktava MKL-2500 (МКЛ-100)

Tube microphone

Overview

Technical specifications

Frequency response

Application notes MKL-2500

Flute and particularly “shakuhachi", a Japanese flute

Piano:
The MKL 2500 gives amazing clarity and detail to the piano giving a slightly larger-than-life sound, which comes across mainly as emphasised presence.
Set up the mic inside the raised lid about 1-1.5 foot from the strings

Acoustic Guitar:
The MKL 2500’s warm valve sound and tweaked third harmonic distortion is perfect for capturing the warmth and detail of an acoustic Guitar
Set up the MKL 2500 one foot away, aimed at the neck joint at the 12th fret. Each note comes out clear and since the mic is quite close to the guitar, it manages to capture the body resonance of the guitar as well adding an excellent warmth to the overall sound

Solo Cello:
On cello this mic produces a natural representation of the acoustic sound in the studio without sounding scratchy or hard and gives plenty of depth

Comparisons
We did a comparison test with the Neumann (U89 and M150), Manley and AKG (C12) Valve mics. The Oktava matched the Neumann exactly (a good start), and with a little EQ, copied accurately the Manley's rich bottom end and "grunt", and compared pretty favourably with the AKG (which in this case is a particularly wonderful and rare vintage model that has recorded many famous vocalists and sax players)
Leo Sayer

A Russian-made, large-diaphragm tube mic which is surprisingly affordable.

Inside the body of the microphone is a 6C315P tube and the power supply has been designed so as to deliberately introduce a measure of third-harmonic distortion with a view to adding both brightness and warmth. A locking ring around the XLR connector secures the included standmount to the microphone, which may be removed to fit the optional shockmount, and a small red LED on the mic body shows that it is powered up.

The quoted frequency response of the microphone is a somewhat vague 20Hz-20kHz, with a sensitivity of 13mV/Pa. No noise or distortion figures are quoted, but then it can be argued that, in the context of studio vocal miking, these parameters are better evaluated subjectively rather than numerically anyway, especially as one of the reasons we use tubes is that they introduce a type of distortion at high operating levels.

In Use

Testing the MKL2500 with vocals confirmed that the tube circuitry has been tweaked to give the mic a slightly larger-than-life sound, which comes across mainly as emphasised presence, though that slightly chesty character that comes with many valve mics is also in evidence. The result is quite flattering on most voice types, and though the sound doesn't have the same degree of silky smoothness as the best tube mics, switching back to an otherwise comparable solid-state mic demonstrates that the tube is doing something musically attractive. In fact the only negative comment I can make against this mic, given its competitive price, is that not enough attention has been paid to the mechanical damping of the casework and/or tube mounting, as tapping the case produces a pronounced ring. While this would be of no consequence when shockmounting the mic, it could be a problem in situations where the regular mount was being used and floor vibrations were being transmitted along the mic stand. For that reason I'd say that the use of a shockmount is mandatory with this mic.

Other than the problem with ringing metalwork, the MKL2500 behaved very well, delivering a nicely hyped version of the original vocal, but still with a seemingly natural character. The third harmonic distortion adds a sense of presence and intimacy to the sound, as well as thickening the lower mid-range, and though this may be more contrived than on most 'classic' tube mics, it certainly works musically. Although the mic construction is simple and has a certain retro element to it, the standard of construction seems adequate and I didn't notice any significant background noise during my tests. As I remarked earlier, there are classier-sounding tube mics, but you have to pay a lot more than this in the UK for them, and when you consider that the MKL2500 sells for little more than a solid-state studio mic it would be unfair to be too critical. Definitely one to try if you're on the lookout for something a little bit special in the microphone department, but you don't want to break the bank.

Paul White

Published in SOS October 2003

Q. How do I take care of my valve mic?

Technical Editor Hugh Robjohns replies: I have a couple of 'do's and don'ts' for you.

Never disconnect the mic body from its dedicated power supply unit without turning the power supply off first, and never switch on the supply unit with the mic disconnected.

Never drop the mic (obviously!), and be very gentle with it for a few minutes after it has been switched off. It's usually best to leave the mic to cool off completely before disconnecting, dismantling and packing it away!

When you first power it up, allow up to five minutes for the microphone to warm up and fully stabilise before making any critical recordings.

Valves do age over time and will eventually 'wear out', although this is an extremely slow (and often subtle) process. Changing valves is not particularly difficult in most cases (it's best to refer to the manufacturer's guidelines for instructions on how to do this) and new valves needn't be expensive, but it pays to use high-quality valves.

If you are using the mic on and off throughout the day then I would leave it on the whole time. If you are using it for a recording in the morning and then maybe again late at night, I'd probably turn it off in between times.

Published in SOS July 2004