Alright ladies and germs, here is another exciting installment of AMP vs. AMP!!!! Or in this case, RESISTOR BOX 1 vs. RESISTOR BOX 2!!!
Yeah, I know not a very thrilling title. Sorry.
To recap for those not paying attention, or with short memories, or too lazy to read back a few pages in the thread, I asked Jan Plummer to make me 2 balanced resistor boxes to go with my Millenia amp. One of the boxes has Jan's standard concrete 5% resistors, one has Mills low-inductance 1% resistors. I don't know which box has which resistors (though I have a suspicion, probably wrong). I have spent the last several days comparing the two, using the same songs I used to compare the other amps I reported on earlier in this thread. I matched SPLs, and actually tried a couple of different volume levels to see if that made any difference (it does, a bit). I first listened to each box for all of the songs, writing down my impressions, then did a back and forth session on individual songs to get a better sense of how they compared on each song. I did this because I wanted to make sure that the different words I used in the continuous sessions really described differences when listening to a particular song, one box right after the other.
After several hours of critical listening, I can tell you that there is a clearly audible difference between the 2 boxes:
Box 1 has a richer, warmer sound -- very tube-like. On some songs that warmth is really engaging, even thrilling, as it provides a life-like presentation that just envelopes you. On other songs the warmth intrudes a bit, with the bass slopping over just slightly into the mid-range and covering up some of the detail. Even at its worst though, the sound is still extremely good -- excellent energy across the spectrum, with the high end particularly well-presented: Cymbals and any other percussive instruments sound spectacular, as the entire range of their sound is transmitted, with clear strike, reverb, sustain and decay. Cymbals are never hissy. There is NEVER any harshness. Period. You can listen to the Red Hot Chili Peppers for hours and not get a headache (I know, because I did it). Voices sound particularly good with this set of resistors. As I said, the price paid for this warmth is a bit more bass boom and a tiny bit of muddiness in the lower registers of pianos and in other acoustic instruments in the lower part of the spectrum. On a big-band jazz tune, the mids can get a bit overwhelmed, and the overall sound can be a bit muddy. The problem is less obvious with electric instruments.
Box 2 is cleaner, clearer, more analytical-sounding -- more like what many of us expect a solid-state amp to sound like. Bass is tighter, with less boom. The mids are less rich and warm, voices in particular sounding colder. The high end is slightly hissier. There is a tiny bit of harshness up there on horns and reed instruments. Nothing awful -- not even close to the MJ or Emotiva levels of harshness. Just more than the Millenia has with Box 1. I will note that when I first connected Box 2 after hours of listening to Box 1, I was dismayed by the initial sound. Where did the Millenia go? How'd the MJ get back in here? But after only about 1/2 an hour, the sound clearly changed for the better, so I'm guessing that these resistors needed to warm up or break in or something in order to sound decent. After a couple of days of listening, Box 2 is much closer to Box 1's sound, particularly if I bump the volume up from 75dBs on my phone sound meter to 80dBs. Then the second box's sound gets a bit richer, the high end gains a bit more depth, seeming less hissy, without losing the cleanliness in the bass and lower mid range.
Which is better? I guess that depends on which you like better: tube amps or solid state. On balance, I think Box 2's flaws overall are smaller, less intrusive and less obvious than Box 1s, and I think the sound has improved enough that it will carry the TBI flag into battle against the Cyclops. But I reserve the right to change my mind (hey I paid for both boxes!).
Oh, and I'm guessing that the Mills resistors are in Box 2, but I'll ask Jan on Monday for the answer (I'm not opening these boxes...).
Next up I will provide a more complete write-up on the Millenia's sound. I've been hinting at it in various posts (including this one), but never really provided details. First, however, I have to go feed the dogs, and then pick some peaches before the bugs and groundhogs eat all of them. Stay tuned for another installment later (probably much later) tonight.