MP32

The MP32 is a class A, discrete differential input, transformer output preamp.

The transformerless input gives this preamp an extremely fast transient response while the transformer output adds a touch of "iron" warmth.

The result is an extraordinary crystal clear but warm sound, without the "clinical" sounding of some transformerless designs.

The MP32 is great on all transient rich sources like acoustic and percussive instruments, and in all distant miking applications.

Highlights

• High quality Wima film capacitors for microphone coupling
• Compatible with the 2520 pinout, it can receive many discrete Op-Amps.
• Compatible with many output transformers like Cinemag, Lundhal, Edcor
• 60 dB of gain
• Dual gain potentiometer for precise gain setting, even at high gains
• Signal/Clip LED monitors signal with full wave rectifiers
• All low level signals switched by relays
• Golden contacts on relays and switches
• Local voltage regulator for compatibility with all DOA's and better channel separation
• Neutrik XLR connectors
• Nicely damped quality conductive plastic potentiometers
• 1% metal film resistors
• High grade 105°C low ESR electrolytic capacitors
• WIMA film capacitors
• High grade double sided PCB with plated holes

Output transformer options

Cinemag CMOB-2H : This transformer has a high nickel core (80%) giving very low distorsion at all frequencies. It should be prefered when looking for sound transparency.

Lundhal LL1517 : This is also a great transformer when transparency is wanted with very large bandwidth and low distortion.

Cinemag CMOQ-2S : This quadfilar line output transformer has a steel core and will produce some "iron" colour, which is a subtle fattening in the basses.

Edcor WSM600/600 : This steel core transformer has a smaller core and will produce an even more coloured type of sound.

Other transformers : The four above transformers are available as options in our kits but the MP32 can work with many others. Look at the "MP32 Output transformer options" document here.

Discrete Op-Amp

The best results will be given by DOA's that are optimized for low input impedance.

SK99B : A low noise, high performance discrete Op-Amp that will perform extremely well in the MP32.

SK47B : A discrete Current Feedback Op-Amp that is pin compatible with the 2520. Low noise and very musical distortion characteristics make it a very interesting alternative.

Other DOA's : The two above DOA's are available as options in our kits but the MP32 can work with others like John Hardy 990C.

More details...

The phantom power is applied to the XLR pins through 1‰ matched resistors to keep the CMRR high. The 48V voltage is filtered by a double RC network to eliminate any residual noise.

The DC insulation of the DOA's inputs is made by large film capacitors which do not present the distortion problems of electrolytic caps.

The gain level is set by a dual values potentiometer and a switch that splits the gain range in two : “Lo gain” and “Hi gain”. This allows a precise gain setting even in the high range.

The clip LED if fed by a full wave rectifier. It will flash green with audio levels of 40dB below clipping giving a visual feedback of the preamp activity. It will flash red if the DOA reaches the clip level, which should be set to 3dB below the actual clipping.

The audio supply voltage is regulated on board, in addition to being regulated in the external PSU. The voltage can be set between +-12V and +-24V. This ensures a very stable supply and an excellent channel separation. The relays and LED supplies are taken pre-regulator. The ground return is split into two paths, Signal and Power, giving a very clean ground reference to all the critical stages.

* API is a registered Trademark of Automated Processes Inc.