Thanks to Groovy Sauce and Kamran…I am now a week into using the Stradi 5U4G rectifier tube in my preamp and I have to agree it is exactly how Groovy Sauce and Kamran portray it to be.  Just stunning detail, clarity, 3D soundstage, instrument separation, clear bass punch and timing. Highly recommended here as well.  Stradi (short for Stradivarius ) is easy to work with, and very responsive with good communication.  They take a few weeks to arrive from S.Korea well packed.  At ~$300 it is a great value and competes with tubes more expensive. It is a very modest and compact rectifier in appearance similar to old stock RCA/Sylvania ST tubes but looks very well made.  On a side note: The Stradi rectifier out performs the Space Lab STR-104 mk2 Super Rectifier in my preamp on my system as well.  Thank you Groovy Sauce and Karmran for your recommendations.  I would have never known about Stradi if not for you guys👍👍
https://www.straditube.com/

CAJames- yes for some unknown reason the STR just didn’t improve the sound on my Supratek preamp but the STR was a significant improvement on my Torii Jr v2.  Go figure?

I should also add that John was extra careful to not ship me a replacement from the last production batch. He asked me to wait a few days until they produced another batch of rectifiers, so my new one is literally right off the production line.

I'm using Stradi AD1 in my other amp.  Excellent tubes.  I was using EML and wasn't happy.  the vintange Tungsrams were good at about $800/pair on ebay.  But the Stradi are better.   very happy.

Now they are building my Sarah 300B.  Stradi offers 2 different 300Bs.  I'm considering these along with the WE 300B which the amp was built around.  

I'l probably pick up a Stradi 5U4G while I'm at it.

Jerry

Hi guys.

I'm looking for a some feedback on Stradi 5u4g, from anyone that has some experience with it. I know the DGR has sucked a lot of air out of the room this year but I need a rectifier for my UFO25 and don't have the space or funds for one this year.

I see Kamran had an arcing issue. I'm wondering how the followup experience went?
I'm curious if Kamran, Groovy, Hereafter, or anyone, has come to a conclusion about the Stradi 5u4g in your system. I did order one and after asking about the 40 microfarads rating of the tube with my UFO25 and it's 47 microfarads, he cancelled my order. I was looking forward to trying one. Am I thinking correctly, the max output of the amp would favorably live under the max input of the tube? Is it worth pursuing or should I move on? What's your take?

Kevin

I used a Stradi 5U4G in my Taboo for several months with no issues.  Once the DGR JR. arrived and became one with my Taboo I bought a second Stradi 5U4G.  I now use the Stradi pair in my Aric 300b Super Set Amp.  Love the way they sound and perform and I have had no issues with them.

Thank you Hereafter

Wow, a second Stradi, that's tellin me something.

DGR JR sounds impossible to argue against, for now, it's on my horizon.
Mystique Y NC DAC in a couple of weeks

Kevin

Quote:


I have posted about the filter cap several times, but I'm too lazy to rewrite, or find and copy one of those old posts. Long story short, in a UFO amp the filter cap rating isn't what matters. What matters is the maximum or peak anode current the rectifier can survive when the amp is turned on and the filter cap gets charged for the first time. In the old days tube datasheets would include that rating and it was generally 1 amp or more, which several times what the rectifier would actually see in your amp. And those tubes usually exceeded their minimum datasheet values, often by a lot. That is why many of us have used rectifiers with ratings of 8 uF or lower in our UFO amps with no issues.

But current production tubes aren't made or tested the way they were back in the day, and peak anode current isn't a spec that today's tube makers publish. So some people have issues with rectifiers arcing or failing outright even though they are "rated for a 47 uF cap." It seems like Stradi tubes are more reliable than a lot of Chinese rectifiers, but tubes are a fundamentally analog device and any tube can fail at any time. That's why it pays to always have replacements on hand.

Thank you CAJames

Yes, I am familiar with your thorough, informative, helpful, and easy to follow explanations on tubes, etc.  Your, and all the other's shared experiences have been my schooling in this wonderful hobby..

While ordering,  I was trying to follow that wider view. I think when I questioned Stradi if the 40 microfarads of tube/47 of UFO25 difference was very meaningful, he cancelled the order rather than mess with me 🤷‍♂️. Guessing, something like, "tubes are fundamentally analog devices and can fail at any time ⚠️."

Kevin