Hey Guys,
since some days I'm a proud owner of an ECBA, starting with basic tubes sold by Craig (EH 300B, TS 6SN7). The ECBA is truly magic, and now I'm planning to get at least some tubes for rolling in the future.
I plan to go for one set of excellent tubes, I've heard before the EML 300B Mesh and I liked it quite a lot. Now I'm thinking going for them or their their companion, the EML 300B-XLS. Another option would be to go for the Sophia Electric Royal Princess 300B. I know that it's mainly depending on personal preferences, but probably you could help me to decide which tube to go for. I love to have a great soundstage with precision, but more then anything else I like musicality, which means naturalness. Maybe this helps a bit.
First Thing: Congrats on the ECBA! Still my favorite amp from what I have had/heard so far...
Second: rosgr63 knows his stuff. If you can get a good pair of KR PX-4 tubes (and your BA has the PX-4/300B switch on the back), that is my favorite pair of tubes. Best mids to me with my HD800.
BUT: you have to change the voltage to 4V on the ECBA external power supply. The 300B tubes run at 5V. You will burn through your PX-4 tubes faster at 5V.
Third: I actually preferred and bought EML 300B
Solid Plates over the Mesh Plates for my HD800. YMMV. (I did a comparison with both sets in-house over some time before I settled on my choice). I use them as a different sound from the KR PX-4 and as a back-up set in case anything happens to the PX-4. If you use different headphones, this can definitely flip towards the Mesh vs. the Solid Plate 300B for some. I didn't like the mids/treble of the Mesh/HD800 combo though- accentuated the treble peakiness and scoop of the mids for me with the HD800 (FR already shaped that way).
Interesting NOTE: If you do get the EML 300B Mesh Plates for your tastes/phones, you can try running the EML 300B Mesh Plates on the "PX-4" setting (switch on the back of the amp). Craig actually did think that sounded pretty good. At least different. He also didn't think that would be bad for the tubes. (Again, the 300B should be set at 5V on the power supply- regardless of switch on the back of the amp.)
Fourth: Be careful purchasing either the KR PX-4 or EML 300B-XLS with the correct base. The KR PX-4 can come with a
UX-4 base or a B4 Base and the EML 300B-XLS comes with the
UX-4 base as standard with the
Octal base as an option for a special center-tapped configuration (I would recommend checking with Craig if you are going to try one of the EML 300B-XLS tube types). Most BAs come with
UX-4 base sockets and adapters from UX-4 to octal have to be custom-made. I think most KR PX-4 and EML 300B Solid/Mesh Plate tubes come with UX-4 bases.
USA UX-4 & European B4 bases have 4 pins, octal bases have 8 pins.
EDIT: Corrected and added some information to the above, plus have some reference pics below...the KR PX-4 can come with a B4 base which would need an adapter to be able to fit in a UX-4 Base. Probably rare, but my KR PX-4 are B4 base and needed an adapter to be able to go to UX-4 Base. I didn't mention that because probably rare but people are paying attention to my post, so I share at the risk of making things more confusing. Looking these up to ensure proper compatibility will hopefully save somebody some hassle.
UX-4 socket (USA & usually on BA) + usually 5V:
B4 Socket (European) + usually 4V:
They even make combo UX-4/B4 sockets:
(Got these socket shots from Jac Music, just for reference.)
Special version: EML 300B-XLS = Octal Base as standard
Here is purrin's thread on modifying the BA to be able to take PX-25 tubes:
http://www.head-fi.org/t/598460/eddie-current-balancing-act-mod-for-px25
And here is purrin's B4 to UX-4 adapters, mine were made (as rosgr63's were) by glenn2359.