@ardbeg1975
How much of a change/improvement to expect of rolling specific tubes on this amp (in 300B configuration)? in general with an amp with 3 kinds of tubes...
I mean rectifier vs input vs output.... all 33.3% - equal?
Or would one experience more of an improvement when focusing on rolling rectifiers?
Or should I f.e. get decent rectifiers and input tubes and "go all in" on 300B (TMs)...
hypothetically speaking!
All three tube types (rectifier, input tubes, and power tubes) impact the sound signature but here are my general impressions of contribution by each type. Your investment in alternate tubes by type should be determined by your prioritization of these contributions. Rectifiers most impact the transients handling / speed of the amp on the wet / dry continuum. I find new issue and NOS 5AR4s (particularly metal base NOS Mullard GZ34s) to be particularly "fast" and SS-like. I personally prefer the new issue Takatsuki 274Bs over the NOS or new issue 5AR4s as the transient handling of that particular tube is more middle ground between wet and dry / slow and fast. The input tubes, as the first gain stage, contribute firstly, in my view, to micro detail and secondly to FR handling by which I mean you can hear subtle changes in the emphasis / ratios of bass, mids, and treble in the overall mix. In this area, I much prefer NOS 6922 variants compared to new issue as the vintage tubes tend to be more textured in their detail handling and less stark in the transitions from bass to mids to treble. The power tubes, i.e. the various 300Bs and NOS versus new issue 205Ds, seem to contribute most to sound stage and the sense of energy in the sonic arena. They, of course, also contribute a lot to the bass, mids, and treble handing and their contributions to the ratios / mix of bass to mids to treble are more immediately noticeable to me (compared to the input tubes) as they are providing the power / drive. In the 205D space, the new issue Psvanes are very nice tubes but the treble handling is very noticeably better with the NOS WEs (it better be given the costs and rarity of NOS WE205Ds in good condition). The bass on the NOS is subtlety more textured but the new issue 205Ds still have very stellar bass on the HP205D amp. I don't have any experience with NOS 300Bs but regarding the new issue 300B "holy trinity" of WEs, Elrogs, and Takatsukis, my earlier posts have discussed their differences. To briefly summarize, the WE300Bs are the most mid-centric with a very sweet and euphonic presentation and, while they do well across genres, are just heavenly with specific genres like, for example, vocal Jazz, acoustic, etc. The standard Elrogs are extended in the treble and bass, are much less sweet in the mids (more "modern" sounding), and engaging but not as smooth as the WEs. The Elrog-MOs are more textured in their bass and treble compared to the stock Elrogs, a bit less aggressive in the presentation (a little less petulant than the stock Elrogs), but still less laid back than the WEs. I prefer the Takatsuki 300Bs as they are a very nice middle ground between the WEs and Elrogs.
So, where should you focus your investment? I'd advise listening to the stock tube complement of the HP205D and then rolling alternative rectifiers, input tubes, and/or power tubes (or leaving as stock) based on how you prefer you sound signature. I've rolled alternatives into all three but that is not necessary for everyone depending on their individual tastes in sonics.
To answer a more fundamental question -- how is the HP205D amp as a 300B amp? Would I take it over, for example, a Felix Envy? I think the Icon is a very good 300B amp and I would take it over the Envy even if it were soley a 300B amp (suffice to say the Envy is not for me but I am likely in a minority in that sentiment). Would I take the Icon over an Eddie Current Studio B as a pure 300B amp? It is a close call but the EC is an epic 300B amp and would win that contest. However, expanding beyond just 300B tubes and rolling in the NOS WE205Ds, the Icon is my favorite DHT amp to date.
