I'd post this is AudioAsylum.com under amps/pre section. Victor, one of the BAT owners, and the designer, usually replies.
I have Amperex 7308's Orange globe logo in my BAT vkp10se phono stage. Sounds wonderful...replaced the stock sovtek 6922's...
I have found that the BAT preamps don't care for the 6DJ8s. I have tried the Bugle Boys and they were fine for about 10 minutes and then things got noisy. If your determined to roll some different tubes into the 5i I would recommend a 7308.
You may think I am joking here, but I am not. I have had good luck with Sylvania/Phillips JAN 6922 which you can buy from PartsExpress.com for $7 each.
The Phillips JANs work fine, as do the Sovtek 6H23s. Better 6922s or 7308s work even better. If you are interested in some 6H23s with very few hours on them, contact me off-thread and maybe we can work something out.
I have tried a ton of different tubes in the VK5i. I found no problems with the 6DJ8, but mostly I used 6922's I actually prefered Mullard over Amperex. For what it's worth to my ears there wasn't much difference between the high buck Amprex's and the less expensive Bugle Boys.
I found out something very interesting though. You can achieve excellent results by only replacing the 2 very outside tubes ( towards the front ). I found this to take that bit of glare of the mids, and highs that the Sovteks had. And also it was much cheaper to only replace 2 vs 6! In replacimg only the 2, I found Telefunken to be the best choice.
Another thing you can try is to replace the two 5881's ( you can use 6L6 tubes here ) In this case I liked Sylvania 6L6GC's But there were many others that produced a pleasing tone.
Of course all of this happened in my system, and with my taste for sonics and music.
I thought Id post this as usefull and helpful info for someone looking at tubes for the BAT 5i. Even though the thread is a bit dated now... I ran across it during a search regarding info on BAT 5i pre amps which I own.
I have also replaced the Sovtek 6922's with 6 Siemens 7308 gold pins on the 3 gain stage 6922's in a row for each side. The front outer 2 6922's which are used as AC shunt voltage regulators, I replaced with Amperex PQ(white globe) 6922(not PQ 7308 here) This set up is WAY better than stock and I cant say enough regarding the transformation of sound. Very recommended.
Finally, I have found a pair of Sylvania NOS 6L6 GC and am awaiting their arrival to check out these .As KT_88 found them to sound good in his 5i.
One thing about using 6Dj8 Bugel boys or any 6DJ8 is that they tend to become very microphonic as they age near to the latter part of it's life. Unless your 6DJ8 test very strong, I wouldn't use them is this application, Of course the 6922 was designed to be quieter than the 6DJ8 and the 7308 even more so. I will visit this thread again with news of the 6L6 GC Sylvania and how I liked it. Enjoy!
Would like to update here as I have listened to the Sylvania 6L6GC in the BAT..First of all, Its BIG..Very big. You will have to go topless with this 6L6 as the cover wont fit back on..So you'll have a BAT convertible! This was what I thought might be the case after seeing them in a photo prior to purchasing.As for sound..Very smooth and slightly warmer and deeper bass overall over the stock Sovtek6L6/5881 tube. The real suprise turned out to be a pair of JAN Philips 6L6. Has all the traits of the Sylvania's and you can keep the cover on to boot.
I changed out the 5881's with Sylvania NOS 6L6WGB -military grade, brown bottoms to great effect..I changed the front outer two 6922's with Amperex 6DJ8's orange globe, steel pins made in Holland...awesome tube! I have some Amperex 7308 white labels coming my way soon and will let you know the results. These changes increased resolution, musicality, added real life and flesh to the bone....Ain't this fun?
Just swapped out the JAN Philips 6L6WGB's for the hard to find and awesome Tung Sol 5881/6L6. These are USA NOS from about 1958 vintage according to dates and test better than new. WOW!!! What a smooth sound from these. Easily the best! of allI've used. If you can find a pair, I VERY HIGHLY recommend them!:)
I bougth 8 amperex 7308 qnd 2 tungsol 5881 - the sound became incridible-how is posible to join equipments distant 40 years old in the time and get the most wounderfull sound , one of mysterys.
George- Yes. Incredible..The NOS tubes really sing in the BAT . Enjoy your 5i!!--Ken :)
thanks for the heads up...I have a pair of NOS Sylvania 6L6GA's "coke bottles" coming my way and will let you know....Now I'm running Amperex White Label 7308's and hoping to try a pair of Amperex 6922 PQ White labels in the same set up as yours...tube rolling is fun and not horrendously expensive like changing out components
Try some tube rolling in the Vk-5i next time you need to retube. Mix the Amperex Orange World Logo in along with some A-frame types of the same brand. The ring Amperex have a smooth sound while the A-frame has better definition. Switching them in different locations in my system yielded a focused, full smooth sound. Best of both worlds imho.
now I am using only 4 amperex 7308 white label+ 4 sovetek6922, I think there is only small diference, I put the amperex in the lateral and first one of the 3 socktes, but now I have four amperex for the future. I tried jan philips 6922, but I did not like the results.