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In the Forum: Audio Discussions
In the Thread: Devid Berning amplifiers: the anti-trnsformers frenzy?
Post Subject: IMO the Berning sounds like nice PP with some well done feedbackPosted by Paul S on: 10/2/2007
And I do not mean this as a criticism.
I had for some time an "original" Music Reference RM9, which was made by another well-educated genius, Roger Modjeski. The RM9 was AB PP with adjustable bias and feedback/gain, with 6DJ8 drivers and a choice of EL34, KT88 or 6550 output tubes.
The idea was to set feedback/gain by ear according to the speakers used, but I found that the low-feedback/ Hi gain setting was the only way to get proper timbre, harmonics and bass, regardless of the speakers I used. Yes, bass with more feedback had more "impact", but it was not musical.
I have no idea whether/how the Berning Siegfried uses some "deniable" form/variant/iteration of "feedback" to co-modulate some part of the circuit, but it did sound to me that something in that circuit is sensing and reacting to signal modulations in a way that audibly suggests some kind of feedback to me. Perhaps this is just an artifact of the complex switching PS, I absolutely don't know. Please understand that to me this is not a "problem" on the face of it, since I really don't care about anything but sound in my listening room and decent reliability. I absolutely hear the feedback working in the ML2, and I happen to like the effect a lot. However, the Berning simply does not "breathe" as well as typical decent SETs do, at least when they are in their comfort zones, and it does not offer enough else to make up for this, IMO. Push the amps, however, and the tables turn. The Siegfried may offer "less" going in, but it maintains its character/delivers its best better/more consitently under stress. At least, this is how I remember it. But in any case is this the "transformerlessness" at work or is it some other genius application?
I have not had enough experience with the ML2s to speak of the audible effects of transformer core saturation in the design. In my case this owes to the fact that the amps just stay stable and sound good if they are biased correctly, so the issue has not come up. I would like to have someone listen to my system and point out the core saturation. So far the only thoughts I've had of it were dispelled when I found runaway bias, and correcting that problem brought everything back into focus.
I would be willing to say at this point that my problems are related to ~97 dB speaker efficiency and wayward speaker input impedance, not some problematic quality inherent in transformers. Rather, in the real world I think it is just a matter of matching the amp/transformer to the task at hand in order to get the best possible sound, versus cutting off the OPT to spite possible core saturation.
Right now, in terms of otimizing my present speakers, I would think of adding transformers in the form of LF amps before I ever got into scourging the demon transformers. By this I mean that nothing I have seen or heard to date has convinced me that an OTL variant is The Solution, in so far as one compares audible transformer core saturation problems to audible OTL problems. In fact, far from it.
YMMV, of course; enjoy yourself.
Best regards,
Paul SRerurn to Romy the Cat's Site