Simple reference sound reproduction at stereophile entry level investment

None that affect me

Full warm sound with great depth and resolution.

Needs fairly efficient speakers to sound its best.

I have owned my trusty OTO SE for about a year now and felt compelled to put pen to paper as one of the reviews on this page seems a little off the mark. The OTO SE''s strengths lie in its ability to present a recording in a full and wholesome way. In my year of ownership, I can say that never has it sounded grainy and always has it proved to be the most non-fatiguing amplifier I have owned. The bass is well defined and also controlled for a low powered amplifier. There is great resolution and it never sounds aggressive. This is not the most indepth review you will ever read, but this is really a great amplifier.

Makes voilins and saxes sound as if they were made of glass, steel, granite and poop.

There are none (oops, wrong box!)

You would think this amp is value for money, but nothing could be further from the truth. A similar spec'ed Unison research or Audion Sterling happen to be far wiser choices to go for if you actually had to buy an amp, rather than win one at a raffle.

You want grain? Get the OTO SE. Solo violin sounds astonishingly strident regardless of how sweet the actual recording was. I have rarely heard the Lara St John HDCD sound as bad as it did over an AN CD, oto SE, totem combo,
oh, far too rarely.
Solo violin is a torture test for the oto se. So are saxophones.

Get an Audio NOT! oto SE int. amp today and be the laughing stock of the entire audio world. To be fair, it has a nice set of pots. And you can use it s chassis to play drums on!
They really ring!
So 4 stars for the chassis!
ONE star for the rest!

Similar Products Used:

Audion Sterling, Unison Research Simply 2, Golden Tube SE 40, Cary SLA 70.

Integrated amp, great phono stage, single-ended, solidly built, uses common inexpensive tubes, has preamp outputs.

No 16-ohm outputs, poor documentation and factory support, no dealers in USA at present.

This is in response to Mr. Semi-Humorous to correct his misrepresentation of my review (see dedicated review section on this amp). I didn't win the OTO SE Phono in a raffle, I bought it used for $1295 at Stereo Trading Outlet in Jenkintown, PA, which he would know if he read my review. I doubt that he's had more than a short listen to the OTO, and supplies no information about ancillary equipment used in his "evaluation" (Look, I'm a Reviewer!).

The fact is, the OTO SE is built to a price point, as as such, uses (in its stock form) Russian Military EL-84M equivalents which I like, Sovtek 12AX7WXT amp drivers and an ECG Philips ECC82 line driver. The Pnono version uses (in mine anyway), a Sovtek 12AX7WXT and a unmarked Russian 6DJ8. I've changed all the linedriver and driver tubes to Telefunkens and the phono stage to Bugle-Boys, and the improvement is dramatic.

In addition, the stock OTO SE uses EYO coupling caps. I replaced them with WIMA MKS-10's at the same value, and again, heard a marked improvement. That's the extent of my upgrades, and among the 12 or more amps in my arsenal, it's the cleanest among them, and sounds excellent driving either Tannoy D50's, Spica TC-50's, Electro-Voice Marquis (16-ohm speakers on the 8-ohm taps), and JBL 4312A's. It will expose your source for what it is, as will all good amplification equipment.

Furthermore, the Signature version, which I do not have, has Blackgates in the cathode bypass position and Elna Cerafines in the power supply filtering positions. Another area of possile improvement is the power supply, which seems to use common diodes that are unbypassed.

Even with all of this, as stock, the OTO SE is nothing to sneeze at, especially when considering the alternatives out there in manufactured single-ended integrated amps with respect to price. While I find Robert Harley laughable at times, his review in Stereophile was fair and justifiably praiseworthy.

Certainly it is far more than a simple drumming surface for an idle mind and unemployed fingers.

This is a 5-star amp stock, and even better with some easy changes, so it gets another 5 stars.

Be a Tissue and Organ Donor and Tell Your Parents to Make It Happen.

Similar Products Used:

Many EL-84-based aps, including EICO HF-81, Dynaco SCA-35, Scott 222D, Pilot 602S, Heathkit AA-151 (all push-pull and all completely rebuilt).

Well, I had to do a core dump on this piece sooner or later.
It all started when I attended the Philadelphia Triode Exposition a few months ago. I had hoped to see/hear the Cary/Audio Electronics SE-1 300B amp kit (or better yet, its Signature version), but never did. What I did hear was a sampling of the best out there in single-ended (and some push-pull) triode designs, along with a couple of OTL jobs. For me, the best sound was delivered by the Atma-Sphere M60 Mk. II Rev. 2's, and the David Berning Seigfried SV-811-10 OTL amps.

But at the end of the show, the four $5 raffle chances I bought going in paid off--I walked out with the final prize, a new Audio Note DAC-1. I talked to Herb Reichert a little (and Dennis Had a bit before that), about my SE quest, but more than before, felt kind of like a groom with no bride. I mean, nice DAC and all, but for what? The TOSlink output of a Sony carousel in my studio? Well, I tried it there, and it was nice, but my search for an SE amp went from casual to serious.

I really wanted to try a kit, but that would mean an amp, which would mean a preamp, and there you go. Dennis Had told me the way to go would be the SE-1 Signature, which adds an input gain stage, but I couldn't find out enough about it--does it have an input selector? Is it a passive preamp in there, a la Jolida? What? And nothing like it would ever come with a phono stage, so there you go again. More money.

Then I swept through the Audio Note website--not the UK one, but the excellent one Herb has (http://www.audionote-nyc.com), and deep in the amplifier section, found mention of the OTO SE, the Soro, the Meishu, and so on. These were integrated amps with single-ended designs, available with and without phono stages, with either parallel tetrodes (6BQ5's in the OTO and 6L6's in the Soro), or single triodes (300B's in the Meishu). Expensive, but nice--looking, anyway.

Then I found a used OTO SE Phono up on The Stereo Trading Outlet's website (http://www.tsto.com). I watched its price for a couple of weeks, maybe more, then talked to them about it, and after much wrangling with my conscience, bought it. Nice place to do business, by the way, but it was the most money I have ever spent on an amp--I'm into HF-81's, SCA-35's, and so on. At least it had 6BQ5s in it, I thought--I won't go broke retubing it with WE 300B's.

So, after lugging it home, hooking it up to PSB 800's, and running a Cambridge CD4SE into it, then through the DAC-1, I got even crazier. I started reading interviews with Kondo-san, from Audio Note Japan, and the Direct Heating Society's website (http://www5.big.or.jp/~dh//) about Sakuma-san's amp designs, and felt I was missing something if I didn't have a coaxial (speaker) driver happening. A Lowther was out ($$$), as was a Klipsch KLF-20 (not a coaxial design, but a high-eficiency horn design that is sweeping its way through the SET community), so I settled for a used pair of Tannoy D-50's (sold as the Profile Plus 635 in the UK).

OK, then, about the amp. It's really an Audio Note UK design, an M1 Phono preamp and a P1-SE amplifier in one box. Decent parts, not top of the line, but better than usual. But wacky tubes--a Sovtek 12AX7WXT and a Philips 6DJ8 (I think) in the Phono stage, an unmarked ECC82 (a.k.a. 12AU7A) in the linestage, and a pair off Sovtek 12AX7WXT's driving Sovtek mil EL-84M's from 1990. More on this in a minute.

In short, the amp delivered on its promise. Balls, unlike many SE designs (there's some feedback in there), a fairly clear high end with no grain, not too much roll-off, as 300B SE amps are accused of having (and seem to when I've heard them), and quiet. And while the OTO's imaging was far and away better than my little HF-81 or SCA-35 mod jobs to which I compared it, they both had enough push, drive, and sweetness that I felt they acquited themselves very well, and for a while I was worried that I spent a lot of money for not very much improvement, until I started thinking about tube replacement.

Then I threw a lot of different tube combinations in there, and what I ended up with completely transformed the amp. What sits in there now is an Amperex Bugle Boy 12AX7 in the phono stage (the Philips 6DJ8 is still in there), a Mullard ECC82 in the linestage (for me Mullards are the kill), a couple of Amperex Bugle Boy 12AX7's in the driver position, and a matched quad of Tesla 6BQ5's in the parallel single-ended amp. BTW, contrary to some reports I've read, the 6BQ5's in the OTO are NOT triode-connected, to the best of my knowledge. No way they'd get 12 or so wpc out of a parallel pair as triodes--more like 6 wpc probably. Anyway, away went what I felt was a somewhat restricted high end, reticent (almost bashful) mids, and in came a sweet, sweet song.

The D-50's are light on the bottom end though, so another deal-maker for the OTO was its preamp outs, which I stuck onto a PSB Alpha One sub's line inputs, and that completed the picture. What now remains is a pure music-making machine. Though the D-50's at 90 dB sensitivity (at 1 W/M) aren't in the super high-efficiency realm, with the sub I still get a clean 103+ dB with some program material before clipping gets objectionable, and that's loud.

Bottom line--this is a platform for listening. A trumpet--Cat Anderson, for example, in the Ellington Band--sounds like a goddamned trumpet. A song is now a song, not a vehicle for evaluating system performance. This rig plays music, and that's the point, isn't it? Say what you will about tweaks (and I get on them a bit as I use Radio Shack RS-Gold interconnects, as you may have read), if it gets you there, so much the better. But it had better be getting you there, or you're just jerking off. I can't think of a more delightful audio experience than the time I've spent than listening to Ellington, Jaco, Quincy Jones, Billy Strayhorn, Johhny Hodges, Robben Ford, Hendrix, or Horowitz through this amp. And that's with CD's! It's made right, with the right attitude. And it's now the reference for every other system I have in the house.

Five stars (what else?).

Be a tissue and organ donor and tell your family to get back!