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Re: what are good sounding circuits for Electraprint choke-splitter?

Posted by dave slagle (M) on March 15, 2007 at 19:02:50

In Reply to: Re: what are good sounding circuits for Electraprint choke-splitter? posted by rdf on March 15, 2007 at 13:46:57:

A few things to take into consideration.

The circuit is essentially a grid choke on the grid of one phase that is also the primary of a 1:1 inverting transformer feeding the other phase. (i know i harp on this)

the grid choke half will give you a darn near perfect square wave and as many have measured the inverting side can give you some interesting behaviors. When you add the perfect signal to the imperfect signal you do not get any sum/difference oddities and the imperfect side is 'temperd' by the perfect side. I think this has a lot to do with the sound of this approach.

In comparison, a SE:pp transformer is going to have two distinctly imperfect square waves, and when you add those signals together the sum/difference waveform becomes much more of a crapshoot.

Moving back to the grid choke / 1:1 inverting situation, it is also interesting to note that if an attempt is made to tame any odd behavior by loading, the gain of each phase will decrease as the load is increased but they will not track each other exactly. This means that as you load the secondary to fix a mismatch at HF, you will create an overall gain mismatch between the phases. Of course once measured in circuit, the gain mismatch (if judged excessive) could be corrected for by spec-ing an inverting transformer with the appropriate step-up ratio for the load required to neaten up the high frequency behavior.

all of the above will net you the circuit that measures the best which by no means suggests it will be the circuit that sounds the best. I personally give a lot of respect to the people who have tried, listened to, tweaked and liked this circuit in spite of the 'measured flaws'.

dave

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