Having just completed the final upgrades to my S.E.X. amp, I'm amazed that it managed to sound even better with the new caps, plate chokes, and OPT's! I got to hear the amp's evolution along the way - last fall, I put in the C4S boards, which made a huge improvement in soundstage, bass definition, and "speed." Then, the day before the MQ irons arrived, I swapped out the coupling caps. Interestingly, this didn't really result in an improvement, though I would guess that the dielectric in the caps needs a while to break in and settle. The 2.2uF value I used also sounded different than the 1uF stock value with the Specos - sort of bloated, but without a lot of deep bass. Then, the MQ updates went in. I had to improvise to hook up the plate chokes, since the twisted pairs going from the "power" half of the tube circuits were too short (probably twisted too finely) to quite reach the choke terminals. So, I used some 16-gauge solid-conductor hookup wire I had laying around to make "new" twisted pairs, even though the wire was a lot stiffer than smaller-diameter teflon stuff!
The two most obvious improvements with the MQ irons over the stock amp with better caps and C4S boards is a) the bass isn't "hollow" sounding or puffy, and is solid all the way down into the 20Hz range. Bass is noticeably improved through both headphones and speakers (esp. the latter - my new H3's are quite the little thumpers!), and b) the amp has lost any trace of mid-range prominence or glare, esp. on instruments like the saxophone. In both the S.E.X. amp and Quickie, I noticed that the Specos sounded a lot harsher (sometimes "shoutier") than my sources in the mids - probably because they were rolling off on either side of the spectrum, leading to a peak in the middle frequencies. The MQ upgrade took care of that, and now, the amp is so smooth and "un-fatiguing" I can hardly believe it. I suspect things will only get better once the caps break in....
Mike from MagnaQuest, just like Eileen and Dan "Dr. Bottlehead," also seems like a great person to do business with. He took time to chat about amps and irons and what improvements I would noticed, packaged up everything very well, and got the irons to me several weeks quicker than predicted. I feel good supporting these small outfits comprised of honest people who are as passionate about music as I am. Too bad the same cannot be said of most of the audio world, with its ridiculous prices, page-long ads and snake oil.
Just two questions: a) I have a hunch that the BH1 OPT's are wound differently than the Specos, i.e., with a higher turns ratio than the typical 1000:1 (8k/8 ohms) to get a little lower output impedance (though the bass is also helped by the higher inductance at lower frequencies, along with the beefier plate chokes). Is that true? Also, how does the enhanced S.E.X. stand up to something like a Paramour? I may build a Stereomour when it comes out, but I would surmise that the difference between it and the enhanced S.E.X. amp (with the Quickie preamp providing extra juice) won't be as huge anymore. Thoughts?
