Hy everybody :-) quick introduction of my self since im new here;-) : bassist from Switzerland, played in several bands and orchestras, Im currently using an orange ad 200b mk3 with an Ampeg svt classic 610 hlf, and a Hartke 3500HA with the matching vx fullstack.
Im reading in here for a long time, and now finally mangaged to register :-)
Recently one tube of the oranges powersection blew so it was time for a tube changing. I was looking a long time in the internet for some information about wich tubes produce wich sound in the orange, but found not too much information.
I was happy with the sound of the stock tubes, but had several smal things that i wanted to optimize. The amp distorted really early so when i needed higher levels i allways had loads of distortion with it. It also had a little weakness in the lowmids and bass.
I decided to switch from the stock chinese made 6550s to JJ electronics kt 88s for the issue with the lowmids and bass.
For the preamp i changed v1 and v2 which were one JJ and a chinese one, to matched NOS Jan Phillips 12AX7 WA that i found at watfordvalves...
The result: Better everything :-) Much more different sounds, better lowmids and bass, and it has now a bit more sustain. Overall the sound is more balanced, and the EQ has more effect. The overall volume didnt change in my oppinion. The amp now stays a bit longer clean, and the distortion is smoother, warmer. The range of sound goes from perfectly clean and precise (hifi like) to hardcore distorted.
I testet with my fender classic 50s P-bass (changed pickups to seymour duncan quarterpounders), with the tone at 3/4 open and the amps eq set on 12. It now sounds even better than before, the characteristics of the amp changed in the way that i can have so much bass and lowmids, that i feel the bass in the stomach and that my trousers are shaking while beeing right in front of the amp, at the same time the sound is slightly bouncy and punchy with the slightly metallic/percussive sound from pic and flatwounds in the background.
I also testet with my Musicman stingray. The effects are similar, with the right eq setting, it has a realy cool funky sound, with lots of treble and bass (realy cool for slapping), and with a bit distortion while playing fingerstile it makes a tone that is close to fleas one in the stadium arcadium album.
I hope that was helpfull
coments and questions always welcome ;-)