Well, I finally threw a gamut of LPs at the ST70 to see how it held up under varying styles of music as well as varying conditions of source material. My long-winded summary follows:
The first LP was Afrika Bambaataa's "Looking for a Perfect Beat 1980-1985". I very infrequently play a track or two off this, so I figured the vinyl would sound clear & clean. My select track was "Planet Rock" (with a prominent sample of Kraftwerk's "Trans-Europe Express"), as this features both analogue synth & digital drum machine. My first suprise came when the Kraftwerk sample was played; here was a literal record of a recording of a record, yet the original Kraftwerk 3-or 4-note melody still retained a semblance of body after being dragged through dozens of circuits. At the same time, the bass was suprisingly prominent, to the point of contradicting my prior assertions of ST70 low-end inadequacy. There was a bit of extension that, despite my general dislike for dance music, made it engaging to listen to. My second suprise was in how much more the digital drums and synths of the early '80s sound when put through tubes. Instead of being the harbringer of the skant, insipid digital synth sounds that would dominate new-wave, they took on a texture that was most likely due to the oft-mentioned "tube coloration" of valve amplification. I'll go on the record as saying I'm for fidelity 99% of the time, but this instance of intonement is rather welcome.
The mono Sundazed repressing of "Soul Dressing" by Booker T. & the MGs, was the second LP. On the track "Tic-Tac-Toe" Booker T. Jones' organ had phenomenal focus, especially on his "expression"; there was a palpable presence in the room, that contrasted nicely in it's call-and-response with the over-driven twang of Steve Cropper's choppy telecaster smatterings. This is the sort of trait I find appealing about older tube gear: what it tends to eccentuate - mid range - is not to a point of exaggeration; rather, it's more like a realism that is a relief to hear reproduced correctly. I should add, too, that this is the sort of sound reproduction that makes it very hard to just listen. I really was getting lost in this wonderful, full-bodied, infectious realism coming out of my speakers.
The ST70 didn't fair as well though, on more modern, rough-around-the-edges recordings (like the punk band, Bastro). More abrasive sounds seemed to knock the wind out of the thing, but only in comparison to it's more-than-adequate performance moments earlier could I really be dissapointed. That said, I actually found myself enjoying the punishment of gnarly, thrashing guitars and the accompanying blitzkrieg of rapid-fire drumming, rather than wincing at the sheer force of the whole sound. The weaknesses here had more to do with the relatively murky recording, however, CD reissues of this material make me think it might have been a mastering issue.
I played a bootleg LP of the Beach Boys "Smile" LP. On this, I was expecting some generational loss, as this is a bootleg. Nonetheless, the mid-heavy harmonizing of the Beach Boys assumed a pleasing raga-like quality that had previously seemed rather thin. Additionally, the soundstaging was transparent enough that I could really hear how patched-together the work-in-progress by the Beach Boys was. The disparate tracks from varying sessions had audible seams in it, which is the sort of pull-no-punches reproduction one should be hearing.
After that, I put on a copy of my German pressing of The Beatles "White Album". Aside from the fact German vinyl from 60s tends to age better than it's US counterparts, I was blown away by some reveals during the track "Yer Blues" that I hadn't heard before. One of which was just how in-your-face and abrasive John Lennon's flanged guitar solo is towards the end, as well as how sharp the cut is that snips it off before the final measures into the fadeout. A second reveal was during the same instrumental measures that precede the fadeout; I could hear John Lennon's verse vocals ("I'm so lonely, wanna die") buried very quietly, as if he hadn't been isolated enough in the studio to keep from bleeding into an instrument mic. This is detail! Guess there's some magic in the mid-range... however, I gotta say, I got nagging low-end issues. Ringo's drums on this record are generally recorded pretty dry, but there is really some dampening in the punch & thwap of the bass drum and the rack toms that make it not sound very life-like. Inversely, there is a lack of sheen on the cymbals that prevents them from hanging in the air until they should naturally "dissolve". It just doesn't do him justice.
Next I put on The Breeder's "Pod", engineered by Steve Albini. Albini is really proficient of capturing the live sound of drums in a room, so I really wanted to test the low-end ambience abilities of the ST70. The separation of tracks, combined with the minimal instrumentation of the songs and soundstaging of the amplifier cooperated very well. I should say that there's gobs of "quiet" on this record, punctuated by overdriven guitar tones and female vocals, none of which are hard for the amp to work with. There's also loads of drum detail on the recording as well, which helped the ST70 along. It would seem that as long as the dynamics of the recording are demanding to much of the amplifier (like the "Planet Rock" track above), it is up to the task. However, if you're pushing really complex signals through it, in stock form it'll need a little assistance. Nonetheless, I heard some super-buried between-track banter I'd never noticed before, so color me impressed.
I finished this exercise with another mono recording, Chet Atkins "Finger-Style Guitar" album. The recording itself is of extraordinary detail as it is, according to the liner notes, Chet Atkins "...playing each selection, just once through... no multitracking." On a track like the Spanish "Malaguena", Atkins warm, fluid, percussive tone is tremendously conducive in bringing out the best of this amp. A vintage recording of solo country guitar on quality vinyl has it's own charms, but paired with the mid-range magic of the ST70, you simply want to build a room around it.
In conclusion, I'd say that not only is the ST70 an affordable entry into tube gear, but is the best entry for audio enthusiasts who are hesitant to pay eBay prices for an "super" tube amp that may very well need some TLC in the near future. If you're willing to commit yourself to a week's worth of construction and a little short-term audio imperfection (find me the "perfect" amp) for very-reasonably priced piece of Americana, there's no better option than the ST70. Furthermore, there's a bevy of aftermarket modifications online for the more demanding specs of audiophile-minded folks, so you really can get out of it as much as you put into it. And there's truly nothing better than pay-as-you-go, DIY style. I'm really hooked.
Best,
Benjamin
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