Coincident Frankenstein mk.2 amps

Crubio,
Speaker tap preference is trial and error, you don't know until you try. My choice is the 16 ohm tap (more open, spacious and dynamic). My speakers are a 14 ohm load so that likely explains my results

Ok, with more hours logged in the amp is starting to open up nicely! First off they drive the speakers with plenty of power. They are dynamic, fast, transparent, and extended at both ends. No warm fuzzy rolled of sound here. Tonal balance is very good.

The EML XLS are very extended and linear, hopefully they will get a little warmer with more hours on them.

The amps still need some more time, but are improving steadily. The midrange hasn't yet fully developed that palpable presence I'm looking for. I'm sure once the amps are fully broken in and some tube rolling in my preamp,I'll get there.

Did anybody try different 6em7 and 5u4g tubes? My amps came with Raytheon 6em7's and RCA 5u4gb tubes. The RCA's were structured a little different from each other. One was taller and had a side getter the other was shorter and had a top getter. I put in my taller black plate straight glass 5u4gb tubes and got a little better focus and the highs became airier.

Hi Snopro,
This is the normal break in pattern and it will continually improve, there's substantially more to come. Remember that those superb transformers Israel chose simply need sufficient time, this is a gradual process. The EML XLS tube gets better as well. This is a very neutral 300b, but you'll gain a bit more warmth with additional playing time. There are warmer 300b tubes available but the EML will reveal the true tonal color and body of instruments without embellishments. It's a great match for the Frankenstein as both are transparent, , uncolored and very honest (but not clinical at all). You'll get the pure organic character and realism without the gratuitous fluff.
Charles,

Joe,
I haven't changed the 6em7 tubes (not many choices available). I've tried the RCA and Sylvania rectifier tubes and there's little difference. The intriguing rectifier for me is the EML 5u4 version. Good comments are made about it but they're very expensive (they're very large tubes as well).
Charles,

Yeah, those EML rectifiers sure look pretty. Maybe somebody on the forum will let us know how they sound.

Joe