In my experience, 0A3. but 0B3 can give you a density that is less warm and very satisfying. . . that's where I ended up when I had Toriis.

Neil, please don’t take this the wrong way…do a google search for Decware Ob3. Or any of the VR variants. Let me explain, I have a ZP3 that uses one VR tube. Month or two ago I put in a Od3 and thought it was amazing. Few days ago I thought I’d try a OC3 to compare the sound. Turns out I don’t have any Oc3’s, so time to do some shopping. First thing I do is the google search, I find it better than the search on the forum. I didn’t come any ZP3 posts but did find a few regarding Torii’s. In one of those posts Will posted a wealth of info. Here’s one post I still had in an open tab.

https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1352304968

FWIW - a Ob3 laid the od3 to waste, the od3 just has rough edges I didn’t like. I lost a good amount of low end going from d to b. I’ve got two Raytheon’s heading my way, a oc3w and od3w. Less than $10 a piece.

Neil…

I just put a Raytheon od3a in my Torii MKIV 25th to try for the 1st time.   I have been running the stock oc3 since I’ve had the amp.  The sound is definitely different…softer, lush, and more laid back.  Yes you do lose a bit of the bottom end, and it doesn’t have that crisp detail by comparison.  But…it’s actually a nice change up, and quite enjoyable.  I’m listening to some Spanish guitar music (Paco DeLucia and Jesse Cook) and it serves this type of music quite well.

I’ll have to report back as it settles in.  Do I foresee keeping this tube type in long term, I don’t think so, but I would experiment…these tubes are cheap enough that it won’t break the bank….$28 bucks a pair delivered.  

As you know…there is a synergy with the other tubes in the amp; and there are a lot of variables to consider like your other components gear that are downstream, cables, room acoustics, personal taste, etc etc.

Hope this helps.

Dom

Your welcome.  I’m sure my impressions will change after I put more hours on them.  I do have a feeling that the bass is going to change and envision that it will tighten up a bit.

I have rolled several VR tubes in my Torii Jr.  and this is my impression and order of preference.  Note: I am running my Torii Jr with a tube preamp which provides additional gain and adjustments.
Westinghouse OA3 ‘67 most detail, punch and liveliness.
Hytron OB3 ‘40’s smoother , tad less lively, good bass, a bit warmer just sounds right.
RCA USN OD3 ‘40’s so smooth and quiet, the warmest tube,  nice detail and bass.  Love the sound but really reduces the gain.  Have to noticeably increase gain adjustment
Sylvania Jan OA3 ‘80’s like the Westinghouse but less of everything, just felt  a little flat not bad just not as good.
Stock Russian VR tube just less of everything and seemed lifeless compared to the others. Put that one back in the box the amp came in.
Just a side note these differences are minor not significant.  Other tubes play a larger roll but I will enjoying moving these in and out when I want a different flavor.