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Michael_Joly · 2nd February 2009

In the specific case of the V67g, I did not find the expense of a new transformer & installation to offer a good return on the investment.

I went into my V67g modifications with the assumption that the transformer would have to be replaced. This was before I actually listened to and bench tested the transformer. But the first thing I did when upgrading the V67g was do a complete gain-stage evaluation - I wanted to see where distortion occurs first. Turns out the FET is the first stage that is pushed into soft clipping. This is good, sounds much better than if the bipolar transistor had hard clipped first. Once I determined the FET stage defined the headroom limitation of the mic I investigated the transformer.

On the bench I did frequency response, distortion (at normal and FET max levels) and phase response tests. I found the results to be entirely satisfactory - again, the FET stage set the headroom limit and HF phase shift way before the transformer affected these criteria.

Then I went and installed a Peluso transformer - sounded very nice also. But in this circuit, there was no measurable or audible improvement. So I decided the stock transformer offered an excellent value and re-installed it.

Its pretty well documented that a transformer swap in a tube mic like the Apex 460 is well worth the time and expense. But in the particular case of the FET V67g, the stock transformer does a nice job of doing what we like to hear with transformers.

2nd February 2009	#106
Michael_Joly 3 + infractions, forum membership suspended. Join Date: Nov 2005 Location: Cape Cod Posts: 2,735	In the specific case of the V67g, I did not find the expense of a new transformer & installation to offer a good return on the investment. I went into my V67g modifications with the assumption that the transformer would have to be replaced. This was before I actually listened to and bench tested the transformer. But the first thing I did when upgrading the V67g was do a complete gain-stage evaluation - I wanted to see where distortion occurs first. Turns out the FET is the first stage that is pushed into soft clipping. This is good, sounds much better than if the bipolar transistor had hard clipped first. Once I determined the FET stage defined the headroom limitation of the mic I investigated the transformer. On the bench I did frequency response, distortion (at normal and FET max levels) and phase response tests. I found the results to be entirely satisfactory - again, the FET stage set the headroom limit and HF phase shift way before the transformer affected these criteria. Then I went and installed a Peluso transformer - sounded very nice also. But in this circuit, there was no measurable or audible improvement. So I decided the stock transformer offered an excellent value and re-installed it. Its pretty well documented that a transformer swap in a tube mic like the Apex 460 is well worth the time and expense. But in the particular case of the FET V67g, the stock transformer does a nice job of doing what we like to hear with transformers.