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www.advancedaudio-europe.com Advanced Audio Microphones Europe take care of ALL European sales and warranty. info@advancedaudio-europe.com

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Due to the boutique nature of our microphones, each one spends some time on the bench. We strive to ship within 72 hours of an order being placed.Questions? info@advancedaudio.ca

Apex 460 Upgrade $339.00 USD

Apex 460 Upgrade Apex 460 Upgrade

This is the mod that started it all!!

Before Advanced Audio Microphones was even conceived Dave upgraded two of these for Paul Baker with the exact mod we still do! The rest, as they say, is history.

 

We begin by changing out your stock capsule for our AK12. The amplifier circuit is modified and the proper tube is put in. The transformer is replaced with our dual bobbin BV11 transformer and a brand new CM12 sleeve is put on there to match the beautiful sound! The power supply is also optimized to the correct voltage.

We recommend our upgraded, heavy duty Z312 shock mount.

Dave's Tech behind it all:

The APEX 460 microphone and its many alias counterparts are excellent platforms for being upgraded into a first class studio tube microphone.

This body can be efficiently disassembled with all parts being easily accessible with a Philip’s screwdriver and temperature controlled soldering iron.

It is also used by a number of professional microphone manufacturers beside ourselves as a platform for microphone builds. Some folks using this body but making changes to the electronics are Peluso, Telefunken, Avantone, Stellar, Nady and ourselves in the CM12/CM12SE models.

Our good friend Brian Fox at Fox Audio Research also used the “460” platform for some of his builds and Brian and I have come to the same conclusion with regard to the original circuit which has some design mistakes which can be corrected to produce a first class “state of the art” tube microphone head amplifier.

Some of the misgivings from the original “460” build are as follows:-

  • The “S” or sibilance sounds are often distorted or “grainy” sounding and there is a lack of low end definition in the response.
  • The response can vary greatly from one “460” microphone to the next as there are inconsistencies from these economy capsules.
  • The low end response is very “murky” and undefined as a result of a flaw in the amplifier circuit.
  • The stock 32mm capsules has a rising high end response with often a 4-6db rise in the 3-5khz area in Cardiod.
  • The rise upper mid response in the capsule and the flaws in the circuit design can produce an edgy or “brittle sound.
  • The shock-mount is not robust enough to support the weight of a tube microphone.

There are two incorrect capacitor values (C9/C10) in the “460” circuit. These capacitors should be .001 ufd and were designed to filter out any “Taxi cab” radio interference from back in the day.However, the “460” has .1ufd value capacitors fitted causing and unwanted resonance with the low tech output transformer causing the distortion to increase 4X at 11khz.

 

 

This is the frequency response of the tube amplifier in a stock “460” before any upgrades as confirmed by Fox Audio Research. C9&C10 are creating this rise in the amplifier response at 11khz.Now, coincidentally this rise in the response corresponds to the early roll-off in some of the economy 32mm stock capsule. However, this is at the loss of transparency and clarity because of the increased HF distortion.

 

 

 

 

 

This a graph from Brian Fox Research of the stock 460 distortion in green and the improved distortion figures after the circuit is optimized, capacitors are changed and the tube is changed.

Here is the frequency response from Brian Fox Research after the modification but before the transformer is upgraded.This is the frequency response curve of the 460’s amplifier after our circuit, tube and capacitor changes. This is the same basic tube amplifier used in our CM12. The improved circuit can produce over 10db more headroom than the 460 circuit and is flat from 30hz to 30khz.With our improved BV11 dual bobbin transformer with bi-metal lamination's fitted we get another 6db improvement in headroom (transparency) and a flat response from 20hz to 40khz.

 Now, that the amplifier section has been optimized to be a much more HiFi amplifier with over 10db more headroom and transparency in the both the high end and low end then its time to address the capsule’s response.

The response of the stock capsule at best should look like the RK87 capsule shown below.

 

However, a lot of the “460” capsules we have removed have a response that look like the Black response below.You can see it has nearly a 6db rise at 5khz but is flat at 10khz and rolling out by 14khz. Ignore the response below 100hz. The response in the red has a big rise at 14khz but this can be tamed very easily with a HF shelving EQ but its much harder to duck the upper mids correctly.

 

In our “460” to CM12 full upgrade we fit the AK12 34mm/OD edge fed capsule. The CM12 & upgraded “460” will have the response shown below.

The response is flat through to 2khz where it slowly starts to rise and is up 2db from 3khz to 6khz (sibilance area) then slowly rises to +5db from 8khz t0 14khz. The rise from 8-14khz produces a nice “airy” presence without excess sibilance.

The full upgrade with our AK12 capsule, CM12 circuit, BV11 transformer, 6072a and power supply optimization is $389 with the improved shock-mount. It is shipped back to you with our AA CM12 microphone sleeve fitted and a brand new shock-mount.

 

 

 

 

 

 

 

 

 


 

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