I can help you with OB3, OC3 and OD3 if you're interested. I have pairs of these tube types and try as I might I never prefer the sound with these in a set to the sound of OA3 in a set. . . . I would let you have them for what I paid for them which was about nine dollars a tube. PM me if you are interested.

A great part of the DECWARE family and community is not only do we all enjoy this hobby but people are very willing to give advice and help when it is asked for.

Thanks again Lon.

JD

You're welcome J. I am of course trusting of members of this forum, and the post office is a part of a three mile walk I often do, so I got these in the mail just a bit ago. Should have them by the weekend or Monday at the latest (sent Priority).

Also, I have gotten good VRs from Ebay and from https://www.tubeworld.com/index_high.htm At tubeworld click "vacuum tube stock", then "all tubes" and go to the O's at the top. The thing I don't really like about tubesandmore is that different companies and vintages make a difference, so though the prices are really good, I like to get more info on a tube.

Hey Nielwill,

My room is pretty live and tending toward bass, so depending on the tube set, and probably taste too, I sometimes find OA3s a little heavy handed..a bit pushy and sometimes dense....Not always, I use them regularly. I seem to tend to use OB3s as much of the time, and I really like some early OC3Ws (two stepped brown base that takes up most of the tube height, and the glass sets into) and a late 40s Hytron OD3 at times too. Generally, the higher the letter, the less push on the power tubes, so more open, less dense and bassy sound.

I think the VR is highly influenced by what it is filtering too...the sound of the power tubes make a mark on the O_3 effect, and the input tubes (and their VR/filters) effect the power tube sound, and the Rectifiers effect the lot....so it is a little difficult to clearly evaluate with accuracy....I will go for tendencies of the tubes.

I find with all tubes, it is not only brand, but vintage. Actually, by appearance some various VR brands are made by the same makers. For example, my 50s Tungsol OB3s seem to be the same tube construction as the Raytheon and Marconi from that era. The Sylvanias I have from then are close, but a little different looking, and sound more articulate and a little less warm. I have not studied this, just noticed it.

I started listening with Chatham 5R4WGY rectifiers, Tungsol OB3, cryoset JJ6CA7s, Lorenz 7DJ8, Ratheon OC2. In the Zstage, I am using a quite warm (but still textured and detailed) Mullard/IEC 12AU7. The overall sound of this set is as dark/warm/bassy as I like to get, on the edge of too dark...and as it turned out, it pushed  the dark/warm factors of the OA3s too much for me. Remember I was using an OB3, a bit less push than OA3s. So I switched the 5R4WGY rectifier for an early 50s RCA 5U4G-ST. This chilled the low mids and bass enough to hear more of the characteristic sounds of these VRs.

I am leaving the Torii adjustments as they are, something I rarely do in tube rolling, loving the fine tuning the treble and bass knobs give us.

When I talk about OA3s, depending on the tube set, off balance in one way or another can be exactly what we want to balance the tube set...Open it up, warm it up, soften it down, or whatever. This is why I will talk about characteristics for the most part. I really like all of these tubes depending on the set with the exception of the Russian, which can be really good if handled well, but there are alternatives that sound more consistently natural to me..easier to use.

When I listen, I really do hear a lot of difference between VRs in most cases. These comments are digging into the sonic tendancies of the tubes...hard listening impressions.

Early 50's RCA ST (coke bottle) silver letters (bottom, wide, horizontal D getter), is most of the time a little off balance to me, with warm/darkish low mids to bottom, open/clarified mid-mids, and perhaps a little touch of top tiz. I usually like this tube but end up hearing too much of this imbalance. But they sound really good with this very warm tube set. The open mids in a warmish cradle is quite good, the bass is deep and tight, and the top a little hyped up, but not tizzy. The slightly excess darkness I usually hear from this tube does not seem there in this set.

1960 Jan/Marshall...white letters ST (bottom, horizontal D getter). Balanced, extended, generally quite open and articulate with a slight sense of warmth and body, giving a natural vibe to a relatively open and transparent tube. This one is notably dynamic with most sets. In this set and with these settings, the tube is a little sizzly mid-mids up. I usually like this tube a lot, better than the RCAs, but not in this set.

1980 Sylvania ST (round bottom/vertical/side getter) Similar to the Marshall, with just a little less extension, but not hobbled feeling by any means. Smooth, very slightly warm, relatively transparent and open generally, a solid and pretty real sounding tube to me in most sets. It feels nice and neutral in this set...open but even.

Tall, straight bottle Russian with a bottom parasol getter. Quite open and clear sounding with a bit of upper mid leanness, and top tiz. Pretty good extension, but less than the above on bottom. Pretty dynamic. With some tube sets, particularly more open sets, I find it little unsophisticated, perhaps electronic and thin feeling, but it can work well with the right tube sets. Over this, I tend to use the 60 Marshall or 1980 Sylvania, having similar open qualities, but with what I find a more chill, solid and natural sound. However, in this set, the less extended bottom, and the very open middle is pretty good. Given a chance to adjust the treble down a bit, I might really like it in this set!

Short, straight bottle Amperex (North American Phillips 1973). Large top hallow getter. This tube is balanced and pretty warm, but in a good way, with good detail. Good for warming a set that is too bright or open without losing detail. Nice power and dynamics. With this set though, I find it is just a little dark and subdued by whatever is bringing the slightly dark density out in this set.

Short, straight bottle Raytheon, orange letters, labeled OB3A, but I think it is very likely an OA3...orange gas. Large top hallow getter. Similar to the Amperex, this tube is warm, less warm, and also similarly open and balanced. Nice sense of dynamics. This is probably my favorite in this tube set...It opens it up without losing a nice warmth....great texture, just right bottom, and smooth, but open top.

Finally, admittedly, I am very intrigued by tubes, and I really I like having a variety to mix and match. VRs at this point anyway, are a relatively inexpensive way to adjust a tube set. The O_3s are powerful tools for fine tuning the sound.

As you can tell from these ramblings, it really is subjective, but also makes a big difference what you put the VR with, not to mention system/room characteristics......So if interested, I would try to get my hands on a small variety of NOS VRs and try them.

For me it is easy to use most decent tubes because I have a good variety of each type, so it is endless what can be done with mixing and matching. but I am probably a tube nutter.

Wow, this is great info.  Thanks, Will, for taking the time to do this.  This is more than I expected but very much appreciated.

Wanted to revisit this old thread with an update. I've really been enjoying Tungsram VR75 in my TORII III.  They've got bottom double d getters and have what looks like a cool smile at the top of the tube when lit. They are easily my fav VR75 and can be found rather cheaply. Sound is tight crisp yet slightly forgiving and ethereal, match wonderfully with el34 and 7308 tube complement. I found a cool seller in Eastern Europe and bought a 8 pair of NOS for under 70 bucks.  

JD

Recently got my Torii III back and have been enjoying some early Sylvania ob3.  Gives me more room to play with the volume than oa3's.  I grabbed some 40's Hytron oc3 to check out as well. If I ever take out these Sylvania I will report back.

JD