K6JRF's Page
formerly W6FZC
Microphone Comparison Page II
(Updated: Sept 21, 2008)

Mic Comparison Page II summarizes the test results of three popular microphones; Marshall MXLV77, Neumann TLM-103 and ElectroVoice RE27. Various frequency and spectral plots using SpectraPlus are included.

Background
I received the Marshall V77 tube mic and was very impressed by the sound of it! Talk about depth without boominess, this is just a great mic.

I decided to sweep the mics in an sound chamber and really see what each could do when compared side by side. The only problem is I don't have one! In addition, I had recently sold the MXL2003 so it was no longer available for this test. But I did the best I could.

SPECIFICATIONS MXL V77
Type: Pressure gradient w/ 25mm diaphragm
Frequency Response: 20Hz-20KHz
Polar Pattern: Cardioid
Sensitivity: 20 mV/Pa
Impedance: 250 ohms
S/N Ratio: 77dB (Ref. 1Pa A-weighted)
Equivalent Noise Level: 17dB (A weighted)
Max SPL for 1%THD: 122dB
Power Requirements: Dedicated power unit (supplied)
Connector: 7-pin XLR
Size: 55mm 195mm
Weight: 525 g
Metal Finish: Silver

MXL V77 Tube Mic

MXL V77 Frequency Response



Audio Sweeps:
This section details the equipment and methodology used in sweeping the microphones.
The 'point' source was one of my Klipsch KSF 10.5 Synergy Tower speakers shown to the right. Click on the link for more details on the speaker.

It features two (2) 10" woofers and a 2" tweeter loaded by a Tractrix 60 x 90 deg horn. The frequency response is 36hz to 20Khz. It Measures 40" H x 11" W x 14" D and weighs about 60 lbs!

I 'dragged' it from the family room into the studio and moved it all around in order to find a position that minimized the room reflections. I did find such a position, but it took about three hours! And that's a story in itself!

The sine sweeps (SS) were made from 30hz to 5Khz. This is a shortened sweep due the restricted bandwidth of single sideband (SSB) audio; 50hz to 4Khz.
Klipsch KSF10.5 Synergy Speaker

The equipment used to perform the measurements was; Preamp, Aphex 107 Tubessence; sinewave source, Sony MD MZ-R55; Power Amplifier, Technics SU-Z25 (30W/chan @ 0.03% dist); Charts, SpectraPlus running on my laptop SENS-810 computer. No equalization of any kind was used to tailor the mic's response. In fact, the Aphex 107 'Tubessence' preamp is included showing it's razor flat response.

Analysis charts are plotted using SpectraPlus (SP) as in my other works. The SS generator is derived from SP in conjunction with my Sony mini-disk recorder MZ-R55. The use of sine wave sweep is an accurate method albeit slower than pink noise, of checking a signal path. Note that only 50hz to 5Khz data is displayed.

Each mic is shown in different colors.
1) The MXL V77 has the deepest frequency response (at 50hz); about +2dB more than the TLM103 and +4dB over the RE27. Note that this is the 'KEY' to the tube sound. Then at 100hz, the RE27 takes over by +2dB. Thus the V77 sounds deeper and heavier than the RE27 which gets a little 'boomy' at 100 to 200hz.

2) The TLM103 and V77 track each other through the 500hz to 5KHz range.

3) The RE27 mic shows as the 'brightest' mic from 1.2Khz on through 5Khz. By as much as +8dB!

The MXLV77 compares favorably with the TLM103 and shows that BOTH MICS TRACK NICELY BUT EACH HAVE A DIFFERENT SOUND! Subtle timbre differences in the lower, mid and upper frequency ranges change the 'flavor' of each microphone.

Sine Sweep of MXL V77, TLM103, RE27

Voice Tests:
The attached chart shows results of audio tests with four mics reading the same material to produce about 30 secs of audio from yours truly's voice. Each mic was equalized to present the 'best' sound (this is very relative!) possible and recorded via from the calibrated FT1000D phone jack into the Sony Minidisk MZ-R55 (20hz to 20Khz). Then the recordings were 'played' back into SP and a spectrum plot of each recorded.

The red chart represents the TLM103, the blue chart represents the RE27, the purple shows the MXL2003, and the aqua shows the MXLV77. The deepest sounding mics are the V77 and TLM103, followed by the RE27. All three mics have similar responses, if not identical! The RE27 has the brightest upper frequency response of all of the mics tested. However it's on the air tests show it to be very heavy in the lower registers which seems to cloud the higher frequencies.

Voice Spectrum of Microphones

Summary:
I spent about 4 hours changing the tonal response of the TLM103 to emulate the 'tube' sound. To do this, you must emphasize the 50hz area.

Here's the settings for the dBx Pro DDP:
Band1 Band2 Band3
50hz 315hz 3.15Khz
4.00 1.00 2.00
+7dB -5dB +7dB

The MXLV77 is a great sounding mic when price ($590 list) and performance is considered. If you want deep, full sounding audio with lots of 70hz to 250hz 'boom', then this microphone is for you.


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