Features:

- Standard 500 series modular size 1.5" x 5.25"
- Single-ended Class A amplifier
- UK made Carnhill/St Ives input transformer
- Custom designed Jensen output transformer
- Stepped gain rotary switch in 5dB steps
- Output level pot for trim and mute
- LED lit pushbuttons
- 28kHz feature brings out high frequency detail
- Custom made Marconi style knobs
- High headroom & CMR, Low noise design

Price $775.00 USD

After some requests from audio engineers, the MA5 was created for the need of a high quality microphone preamplifier in the characteristic sound of early 70's British consoles. The re-engineering in the creation of the MA5 stemmed from years of experience restoring both American and British modules, deeply rooted in classic transformer-balanced, discrete electronics. Only the best and most suitable components are used throughout, regardless of cost, to attain the best sound.

Much time was spent on the MA5, not only on the engineering side of the design, but also to extensive sound evaluations in observation of specific settings, gain structures, and key components, spanning a time frame of a little over a year.

We have always believed that even with some of the best audio test analyzers we own and use, our ears' sensitivity, coupled with good judgement of sound through experience, is still unparalleled. In the end, it is our ears we are trying to satisfy.

Its full and open sound is due to a rich content of harmonics, particularly in the very low frequencies even down to 10Hz and below. The clear mids and smooth highs come through without sounding dull or smeared.

FAQ's

How can I run LINE level inputs into it from my PT's or converters?

Because the MA5's gain is stepped, it can make a very accurate and great sounding Line amplifier to run mixes through and will add it's signature harmonic overtones to the low end. But it's important to make input load and output source impedances optimized.

The LINE PAD-Z is designed for mic pre's that do not have line inputs, such as the MA5, enabling you to plug a line signal into the mic input.

The LINE PAD-Z adaptor serves three important purposes: 1) It provides the proper load to your PT's or converters without overloading them. 2) It drops the level -35dB's in the range of a microphone. 3) It's output impedance "looks" like a microphone to the MA5 preamp, so source impedances are normal.

With the use of the LINE PAD-Z on the input of the MA5, unity gain would be at 35dB position on the gain switch with the Output turned all the way up.

It works very well and could be used with other high quality, low noise preamps. Not recommended for unbalanced interfaces. DO NOT ENGAGE PHANTOM POWER WHEN USING THIS LINE PAD

LINE PAD-Z SPECIFICATIONS:
Made using Switchcraft
Input impedance = 10K ohms
Attenuation = -36dB
Output impedance = 150 ohms

$35.00

If you are purchasing an MA5, you can buy it at the same time. Or buy direct separately.

How much current does it draw?

75mA per rail, so 150mA total. This is about double compared to the current draw of the E27 since it is a class A amp with a big output transistor. But unlike class AB modules, the current draw stays fairly constant regardless of volume or load to the output.

ADDITIONAL INFO:
It is equally important to work out how the power supply in a rack or lunchbox responds to inrush of current to the modules that are in it. All power supplies we tested have current limiting regulation, meaning that the power supply rail will shut off if it senses a lot of sudden current draw, which can be triggered just by turning the rack/lunchbox on with it full of modules.

So always check to make sure all the lights are lit and everything is working when you first power up. If a rail does not power up, and the power supply had gone into its current limit mode, then turn it off. You will have to find a trim pot on the inside of the power supply which regulates the current limit and turn it up one o'clock at a time and retest each time until the power supply turns on without triggering the limit. Be absolutely sure it's the current limit adjust, and not the voltage adjust, trim pot you are turning. Get a professional's help doing this or contact the manufacturer of the rack or lunchbox.

The BAE 11-space Rackmount comes with a large power supply. An example of what the trimpot looks inside is pictured here:

Please contact us if you have any questions and we'll help you out.

What's the 28kHz pushbutton for?

This was an idea borrowed from our E27 equalizer, but this time it's only a 6dB rise and shelving at 28kHz. We realized it was so useful for bringing back life and realism to many instruments, we had to put it in the MA5.

It started when we first heard it on live orchestra music a friend recorded - it made us hear the sound stage and its reflections resulting in a better depth of field. On acoustic guitars, it brought out the upper-end frequency timbre of the instrument. On drums, it sounds particularly nice on the room mic, capturing the natural high-frequency reflections better. Even dynamic microphones can be used in certain applications you wouldn't have otherwise done before.

For vocals, it brought the singer closer without turning up the siblance frequencies. We thought it may be a good idea to put them on vocals as many of today's condenser microphones inherently have a bright top end, which may not be in the right place for a particular voice. Adding 28kHz to this would allow you to use a de-esser or equalizer without loosing too much of the top end detail, and without using too much additive eq later. But this depends on the characteristics of the microphone so be careful not to put the 28kHz on everything!

There's much more to the applications of the 28kHz feature... just experiment.

No DI?

After sound evaluations of three different DI circuits using different bass and guitars for this preamp, we found that we liked the Jensen direct box transformer the best - maybe because the sound went through the mic input transformer as well. It was an immediate winner in tests and had the fullness and definition in the low frequencies we liked. Our best advice would be for you to purchase a high quality DI, like the one made by Radial Engineering using the Jensen transformer which also have ground lift and other features (and no, we have no affiliation with them).

What's the -6dB for on the output pot?

It's a fine trim adjustment to get in between the 5 dB steps of the gain switch. It also mutes when turned down all the way so you could exchange mics and to use phantom power to prevent the thump from the speakers.

No meter?

A meter would be nice to see if there is signal there, but considering how high the headroom is on this preamp (+31dBu into 10kohms, +27dBu into 600 ohms) the meter you should be looking at is the one for your recorder, like an A/D converter, which will clips at a lower level.

Can I purchase output transformers from you for a DIY?

Sorry, no. The output transformer is custom made for us through a research and design collaboration between Avedis Audio and Jensen Transformers in a proprietary agreement. Furthermore, we remain even more vigilant with regards to the potential of the cheap copiers.

Seconds after powering down, it is normal to still hear a loud signal?

Yes, it's the capacitors discharging but keeping the power up for a little while. This is normal for this particular type of Class A amp. It is recommended to mute your monitors or disconnect the preamps from your speakers or headphones when you power down.