[m17xr2b]

Might as well share my thoughts on 2A3 valves:
Sylvania S plate fishing-pole, great tube overall and an upgrade over stock. Lacks microdynamics and air, slightly warm and muffled.
Ken-Rad smoked glass, fantastic extension, super bass punch with control, very neutral, no grain or harshness but lacks ultimate air and soundstage is intimate.
Psvane WR275, fantastic tone, good extension, lacks dynamics, found it a bit flat but great for the price(250$ for pair).
Sylvania dual flat plates, bass is a bit lean but fantastic mid range and treble, relaxed and detailed, mini mono plate sound.
KR 2A3, one of the good originals, rivals RCA mono plates in technicality, highly musical, fantastic low end and treble.
EML Solid plate, dynamics were flat compared to the best, very neutral tone but not exiting
Fivre S Plate, fantastic tone and extension one of the best, no the largest soundstage, too bad it's rare and expensive
RCA mono plates, best dynamics and extension so far, neutral, fast, microdynamics are easy to pick up, musical.
Fivre mono plate, same as RCA mono plates but with additional warmth without sounding veiled.
AVVT 2A3, neutral as can be, best dynamics and extension, no warmth.

 

[DMck2000]

The Stratus after a year has been wonderful. Definitely keeping this amp for life. As of recent, I have been using my new Jomo Flamenco iEMs with the Stratus, and despite some noise (which is to be expected with iEMs) they have been an amazing pairing. In some ways even better than the Utopia.

 

[UntilThen]

@m17xr2b thanks for the write up on rectifiers and 2a3 tubes. That will help me decide on what tubes to get.

 

[claud W]

In none of the pictures posted in this thread do I see a Stratus with tube dampers. Today I ordered 3 different tube dampers for my Stratus from Herbie's Audio Lab. This was just a preliminary order to check sizes. I use Herbies on my Cary V12R input tubes and thought to see if they help the Stratus.
I have had a bit of low level noise from one channel of the Stratus so its time to clean pins and sockets. Sounds like a great weekend project.

 

[claud W]

Has anyone tried the Sophia 300b mesh-plate princess? What about Sophia 2A3 mesh? I know the carbon Sophia 300B 2.5 is supposed to be very good. I was just wondering about the newest, the 300b 2.5 mesh plate princess.

 

[RubyTiger]

Here's an update on the Acme 2A3's. They took a long time to break in. Probably because I was breaking in the KR at the same time. I did swap in the stock rectifier or stock power tubes as time went by though.

Now that I have a couple hundred hour's on them they changed much. If I had to pick I would say the most remarkable thing about them is their clarity. They are crystal clear instead of being dull and veiled. Every thing sound's good about them but I need to listen more. All I can say is that they're sounding more like the $600 tubes I hoped to get.

If your interested I believe the word "airy" was used by Psvane in their write up. I looked it up on Stereophile's audio term glossary: airy Pertaining to treble which sounds light, delicate, open, and seemingly unrestricted in upper extension. A quality of reproducing systems having very smooth and very extended HF response. It certainly does seem to fit their character.

Tubes I might compare them with would be nos Ken Rad smoked glass, Sophia 300b's. `

 

[paulomario77]

I'm using the 422A as my main rectifier but I've asked Donald to mod my amp for it. I find it has the best balance and tone among the others.
Closest is U52, great mid range and extension, bass is not as controlled, slight warm tilt overall, smooth highs 422A is more neutral in tone but treble is not as relaxed.
MWT/RCA 5U4G top getter, got it for 10$, very thin glass, closer to 422A than to U52, nothing was wrong but the other two had X factor.
National Union VT244 foil getter, a great all rounders, blends smoothness and clarity really well, lacks ultimate extension but close overall
Ken Rad VT244, punchy and warm, a real nice hip hop tube but less air.
Fivre 5U4G, lean sounding and bright, might work well for some.
Sylvania VT244, sounded fine, a fine sounding valve, average, could do better.
Stock, worst of the bunch anything is an upgrade.

I've thought about getting the EML and old style KR but decided to stop trying rectifiers.

I'm not for one second suggesting the stock Stratus is not a fantastic sounding amp. Tube upgrades just enhance various areas.

I'm very thankful for your advice, and others`. My Stellaris is due to October, and this is what I have ordered/received so far:

Rectifiers:
U52 (from my now gone WA22);
Sylvania 5U4GB black plates;
WU 5U4G black plates;
WU JAN 5U4G with what appears to be gray plates;
Ken-Rad black plates.

2A3:
Ken-Rad 2A3, dual flat plates, smoked glass;
Fivre 2A3, S gray plates.

 

[claud W]

Have any Stratus owners tried the new ZMF Verite headphones? Like the Senn HD 800s, they are 300 ohm. Might be a great pairing!

 

[claud W]

KR offered to sell me a 4A3 tube for my Stratus. It has a 4V filament voltage. What do you think guys think about this?.
FYI, Sophia Electric has none of the 2.5V Princess 300B tubes in stock and do not know when they will make more

 

[auricgoldfinger]

KR offered to sell me a 4A3 tube for my Stratus. It has a 4V filament voltage. What do you think guys think about this?.

This question is best answered by Donald, but I think I can guess the answer.

BTW, I still have a matched pair of 2.5V Carbon Princess 300B tubes that are priced to move. If anyone is interested, please PM me.

 

[claud W]

OK Brian. PM sent.

 

[Donald North]

Doing a quick sim with estimate for current draw, the KR 4A3 is not a good match. The filament voltage will be insufficient.

 

[claud W]

Thank you Donald. Sort of expected that
Latest setup is spectacular. Ticks all the right boxes . KR 2A3s, U52 rectifier and RT 6N1P with Herbie's RX damper on it. Holographic imaging, big soundstage and dynamic to die for. Its my new base line. Received a new HD 650 from Amazon yesterday and Norne Silvergarde S 3-C coming sometime next week for it.

 

[DMck2000]

Hey just curious, but I’ve heard some people with good knowledge about amplifiers saying that my Utopia’s tuning is being changed by using the Stratus because of its amp topology. Is that case for anyone on here that has used the Stratus with Utopia?

 

[RubyTiger]

That sounds weird to me. If so, wouldn't all headphone's tuning be changed by using the Stratus or is it only the Utopia's?