
SavageRiffer
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Sick Squid":1h15tnjl said:might give that a puntSavageRiffer":1h15tnjl said:I put some 6CA7's in my Helios recently and opened up a whole new dimension. It's smoother, more low end, more headroom on the high input, and a quicker pick response. Some of the mids seem pulled back, but since the Helios seems to like the bass above the 12:00 mark, it seems to work very well. Cleans are stellar and more lively. Crunch is slightly preferable with EL34's only because it sounds grittier, but some people may not prefer that. High gain, whew! 6CA7's are awesome.
Having said that, I tried KT77's prior. I'm on the fence about whether I prefer KT77's or 6CA7's, but I might drop back in the KT77's only because they are slightly more similar to EL34's. I highly recommend experimenting with power tubes in the Helios 50. I have never experimented with tubes in the Helios 100, but I wouldn't imagine it would make as much difference as in the 50. The 100 seems a bit more opened up than the 50, but the 50 is a bit sweeter.
If I had a do-over, I might have chose the 100 only because it has a little stiffer feel. Sometimes the 50 feels a bit spongy. However, the tube replacement has cured all of that though. Who cares man. If you can score a 50 or 100 it doesn't matter. The only real big advantage of the 100 is that you can get a little louder headroom than the 50.
to what level did you bias (not used those tubes before)?
which brand of 6CA7s do you recommend?
I got a pair of JJ 6CA7's in a trade. Not sure of the technical details as I had a tech bias it. I only bias cheap amps with my bias probe. Not comfortable biasing my handwired Bogner. The JJ's are good to me. I've tried some EHX 6CA7's before but couldn't tell you if they were better or worse. They sounded mighty fine though.
Keep in mind that 6CA7's are quite different. Helios cleans are great, but even greater with these tubes. It will have more low end and slightly pulled back midrange. Bogners are warm amps, and the Helios is kind of on the bright side, so 6CA7's will smooth it out a bit so that the high mids aren't as spiky, and the highs will be nice and airy. The lows will be deep but tight. It's really a matter of preference, but if you do try 6CA7's, you should keep them in your Helios for at least a few weeks or a month before deciding if you've already gotten used to EL34's.