It seems that this may not be the best thread for this question or discussion, sorry for that. I’ll likely move future follow ups to a different thread.
To follow up on my question above about new production tubes with a bit more ‘air’ for the Mogwai, after reading a lot of prior tube rolling threads in other amps, and a couple of threads related to recommendations for Mogwai amps (many of which seem to feature NOS tubes quite heavily), I’ve decided to try out some of the current production power tube options in the Mogwai SE. My goal is to share my impressions of the new production tubes in this amp for those who might be deciding whether to try the new production tubes in a Mogwai amp.
Given my target tuning (for the moment at least) described above, as a starting point I’ve decided to try a couple of new production KT77s (JJs which I already had, and are well broken in), and KT88s (Genalex Gold Lion aka GL, not yet fully burned in) in order to get a better handle on what these tubes have to offer and their respective strengths, characters, and perhaps limitations, in the Mogwai (as I hear them anyway) in case that’s helpful.
The basis of comparison and point of reference will be the JJ 6CA7s which came with this Mogwai, with a 6SL7 input tube and a 5U3C Svetlana rectifier.
Of course, since the Mogwai (and Mogwai SE) sound really good in general, my results will reflect my preferences and system synergy, and your mileage may vary…
Fwiw, to summarize my first impressions of these new production tubes in the Mogwai are along the lines of what we’d expect if we are all familiar with these tubes:
6CA7s: Lot’s of macro dynamics, fun, rhythmic & punchy. strong on bass impact.
JJ KT77: Balanced, detailed, neutral, nicely nuanced, tight & punchy, particularly in the bass, lacking a little bit if treble ‘air’ and ‘tube magic’ (for my taste, hearing, system, etc.)
Gold Lion KT88: More extended treble, more ‘air’, heightened sense of the ‘texture’ of instruments and voices. Way more increase in treble air than I had expected. Not bright to my hearing, but more treble energy and sense of presence and impression of the recording space and instruments.
Bass on the GLs so far is not bad but not great, with very good ability to reveal and differentiate different instruments and sounds, but having a bit of bloom, and a small amount of ‘tube’ looseness, and resulting in some lack of ‘focus’ in the bass. Handling of more complex passages is also still TBD. It will be interesting to see if this gets better, or how much better this gets, with more time on these tubes.
I had read about the KT77s “These can give you the mids of an EL34, with the highs of a KT88 and the bass of a 6550.” That sounds about right to me - except for the treble (highs). The treble I hear from the JJ KT77s is not matching (either the quantity or quality of) what the treble that I hear from the Gold Lion KT88s at least. (YMMV of course)
Someone wrote about the GL KT88s: “airy highs, gorgeous mids, deep dynamic bass.” So far, based on what I’m hearing I agree with the first two parts, as I mentioned, the jury is still out for me on the bass of the GL KT88s.
So far acoustic music and vocals are really excelling on the KT88s - think CSNY 4 Way Street, Eva Cassidy Nightbird, Concierto de Aranjuez, etc. Somewhat surprisingly, also Stevie Ray Vaughn, Johnny Lang etc. are sounding good with these tubes as well… I somehow ‘forgot’ to stop the music on Couldn’t Stand the Weather as I’m writing this, and that’s always a good sign.
I would say that the KT88 tubes have added more nuance, detail, texture, and insight to the already significant strengths of the Mogwai in these areas without being at all analytical, bright or fatiguing (for me, and in my system).
On the other hand so far at least, I’d choose the KT77s (or the 6CA7s) for Bluzeum’s Can I get that Funk, or AC/DC’s Back In Black, etc.
So a pretty promising start for the new production tubes as we round the first turn. Actually better than I had expected given that these Gold Lions are still fairly new with less than 50 hours on them. I like both of these tubes in this amp, hoping for some further improvement from the Gold Lions. Time will tell…
So far I’m liking what I’m hearing from these new production tubes. Of course so far I haven’t compared to the best NOS tubes have to offer in the Mogwai. I might yet decide to try some NOS tubes (6550s?) at some point - strictly in the interest of objectivity and fairness of course. It’s likely to be a while though - right now I’m too busy listening to music.
