Ampex MX10, MX35 Mod

Ampex MX10, MX35 Mod
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Reviews Over Ampex MX10, MX35 Mod

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Ampex MX-10, MX-35 Mic Pre Mixer Mod

The Ampex MX-10 and MX-35  are fine little mixers from the late tube era.  The circuitry is straight forward Class A (as are most tube circuits) resulting in an overall smooth, clean sound.  The microphone input transformer is interesting in that it is very small...sometimes referred to as a “thumb” transformer.  Usually a small transformer lacks low end response, as theory says it will saturate easily and thus attenuate peaks of low frequency signal.   Somehow the  thumb transformer in the MX-10 / MX-35 is able to pass low frequencies with minimal saturation.  The saturation or loss of low frequencies is evident when the the signal from the mic is on the hot side, yet still the MX-10 / MX-35 manages to sound pretty good and in fact many value it for the saturation.  A fine sounding little mixer to be sure, but it has it’s shortcomings.


This Mod came about from customer’s requests to have a more complete set of mic pre controls added on to the MX10 / MX35 to overcome limitations to actual practical use in music and sound recording.


The Drawbacks  angry:

  1. All 4 channels mix into either A or B outputs, or both, limiting usefullness in multitrack recording situations. There are no Direct Outs for each input channel.
  2. No input pad 
  3. No phase reverse
  4. No phantom power
  5. No Mute switch


The Solution laugh:

A chassis extension is added underneath the original chassis.  The needed extra circuitry is added in the extension chassis and wires run between it and the original chassis. For each channel any or all of the following features can be added:

  1. Direct Outputs are added for each channel using discreet opamps and output transformers. A 600 ohm load switch adds the needed load when outputs are connected to bridging inputs, which is often the case.
  2. A -20 db input pad is added
  3. A phase reverse switch is added
  4. Phantom power switches and phantom power supply are added
  5. A mute switch is added.
  6. Direct, Mix or both switch added



(Price is for modification labor and parts.  Does not include unit to be modified.)

(Repairs not included)

  • Brand: WPA
  • Product Code: WPA-Mod-Ampex-MX10/35
  • Availability: In Stock
  • $1,499.00

Available Options

Tags: Mod, Ampex, vacuum tube