Elrog 300b's for sale. Your thoughts?

Hi!

The 211 and 845 did not have the issues the 300B had. They did however also suffer from poor quality control. This has been improved as with the 300B. The 845 and 211 also got new bases and better glass and the same improvement to the vacuum.

BR

Thomas

Hello Thomas,
I'm aware of your well established reputation for building very high quality custom amplifiers over many years.  I've read with much interest your detailed descriptions of the planing, design and construction process posted on your site. Knowing that you've taken over production of the Elrog tubes does inspire me and elevates my level of confidence. 

I'm the owner of the Coincident Frankenstein MK II amplifier and George Lenz did honorably replace my failed 300b on 3 separate occasions without any resistance on his part. I know that he was frustrated with the tube failures but he kept his word and never wavered,  I'll always remember the support provided by him. 

I will give the "new" Elrog 300b some consideration to try again. 
1. My experience with the tubes was obviously a poor one in terms of reliability. 
2. My listening experience with the tubes in my Frankenstein was truly fabulous.  The best I've had thus far in terms of musical realism and emotional involvement/engagement. 

Thomas thank you for the Elrog situation update and explanation. If the Elrog can approach the trouble free workhorse durability of the excellent EML XLS  this would be an amazingly good outcome. 
Charles 

Thomas, is there a preferred operating point for the Elrog 300b tubes? For example an operating point of 350v across the plate @ 60mA would be considered a traditional operating point for the 300b. Some amps run the 300b at a much higher point for example 400v or even 450v across the plate @80 or 90mA. Thank you.

Thomas, Thanks so much for your response.  This dialogue with the company is what I hoped would happen when I opened the thread.  I am encouraged by your candor, attitude, and also by the information you have provided on the changes to the tubes and resulting gains in reliability.  As I have said, the Elrog 300b is a tube of stunning beauty.  I want Elrog to succeed and have the opportunity to add additional tubes to its catalogue as time goes on.   I would encourage you to drop by this thread on occasion to provide updates on tube reliability.
I also own Coincident Frankenstein amps.   As you know from my post, when I received my replacement tubes I bought a PS audio P10 so that I could limit the voltage.  In addition, the P10 provides for a soft start up where the initial inrush is limited to 1/2 current for the first 5 seconds.  I almost never listen for more than about 2.5 -3 hrs, so I had hoped to make the tubes work.  I had intended to go with the EML xls as a replacement, and may still go that route.  But I am going to put this decision off for a few months to see what transpires with your recent production tubes in the Coincident amps.   Can you share with us the number of customers currently running your new tubes in their Frankensteins?   I am personally willing to consider the Elrogs again based on your comments, but I would like some statistically significant data on the tube lifetime in the Franks.  I don't expect 0% failure, of course.

All,

thanks a lot for the positive responses and good wishes. As mentioned in my post so far there was a single beta tester who used the tubes in a Frankenstein amp. He had them for almost half a year now. I wanted to have this test first before releasing the tubes for the Frankenstein. Since this release only happened now, there are no additional users of Frank amps yet who have the new Elrog tubes.

@jetrexpo: The choice of operating point depends more on the amp design than on the tube. As long as all max limits are not exceeded any op point which is preferred by the amp designer is ok. 450V/90mA would already be slightly over the limit and thus is not recommended. I personally use fairly traditional op points of about 350V/65-75mA

@brownsfan: The inrush current issue was solely relevant for the filament supplies. When the tube filaments are cold they are basically a short. If the filament supply uses brute force voltage regulation it will push a lot of initial current into them. An external softstart will probably not do much there. We also saw that some current regulated filament supply kits for DIY amps actually start with a current spike and initially put 7V across the filaments before settling to 5V. This is not healthy for any 300B, but it simply killed the early Elrog 300Bs. Also a tube rectified B+ supply doe snot have any affect on slowing the filament inrush current. But as mentioned the tubes are more robust now to be able to withstand some abuse at turn on. Yet a well designed amp with good filament supply and conservative op points will ensure a longer tube life. Not only for Elrog 300Bs but for any brand.

Best regards

Thomas