Anyone have experience with the Tung Sol 7581a vs. EL34, KT66, KT88, 6L6


I broke down and added another power tube (Tung Sol 7581a) to my collection.  That can get expensive as my Primaluna Dialogue HP Premium integrated has 8 power tubes.   

Why has this tube escaped me thus far?  Why is it not more popular?   Many folks don't sell this reissue tube.  

I think this is a great deal.  I was torn between the lush, thick midrange of the EL34 and the more evenly spread out sound of the KT88.  But the KT88, for all its more correct behavior didn't romance me like an EL34.  

The 7581a from Tung Sol can be had cheap and I really like them.  [I'll spare you all the audiophile terms].  They check the boxes that I was looking for. 

Does anyone have experience, information or knowledge about this splendid tube?  

PS  The next experiment is KT150s but I can't see doing it if I'm gonna lose any of that great EL34 midrange. 
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Showing 12 responses by noromance

I tried them last night. Impressions:
Out of the box a little dry but extended in the treble. Very good bass. Clean and powerful sounding making my 1960s 6L6 Ratheon black plates sound a little tired. They did lack the sweet midband of the older tubes but they only have a few hours on them. Overall pretty impressed.

A week or so later. Bass has got really good. Razor sharp. Depth and air have opened up. Highs fine. Midband fine if lacking a little sweetness (color; coloration?) Overall, very neutral, fast and clean. I will swap back my old reference 6L6 black plates to compare and report back.

Follow up on this. I tried putting the old Raytheons back in and it was no contest. Existing attributes have consolidated initial impressions and any tiny lack of midband sweetness now seems like a more neutral clarity, if you know what I mean. Tung Sol 7581a are keepers for the moment. 

Almost 2 years on with 2 x quad sets of Tung Sol 7581A in four monoblocs and they still sound superb. They've held the initial bias settings which indicates good stability and look great.  
Drummer? Then you'll appreciate the new Tung Sol 7581A. Great, clean, snappy bass. Give it about 10-20 hours to sound its best.
@oldhvymec Just checking that you know the thread is about replacing EL34 et al with new Tung Sol 7581A for a big improvement. 

@rshak I found that too. Midband sweetness wasn’t there and they were a little tight. After 20 or so hours, they opened up. I’ve easily 1000 hours on these in my monos (2 tubes each) and they sound sublime.