Depending on the design of the amp, the PI tube can have an impact on the tone of the amp. Generally, in a Marshall design, the impact is small, but nonetheless, it makes an audible difference. Also, the type of PI tube you use will affect the tone simply by the gain factor of the PI tube used. A lot of Fenders were stock with a 12AT7. I've read articles where people were actually using 12AU7's as a PI in their Marshall amps. If you remember, there was an old timer (no, not me)
who looked for help on this thread. He was having problems with an old Marshall amp. Turns out it had a 12AU7 in the PI. No wonder the amp sounded like a cracker box.
People do weird things in an attempt to find their tone. Like a 12AY7 in V1 and a 12AT7 in V2 and a 12AX7 in V3 and a 12AT7 in V4. I say, if you are doing this you shouldn't be playing a Marshall, maybe not even a Fender. That's just plain whacky, but that's a tube line-up a guy posted online. He claimed it gave incredible smooth tone. (And that was all it could do. Probably wouldn't overdrive if you hooked a Tube Screamer up to it.)
The other thing I wanted to discuss is this situation regarding Tung-Sol. I don't mean to cause a panick, but I am passing on what I have found out and info other members know about. The fact is, once you've tried NOS tubes, it would be really hard to go back using NP, especially in V1 and V2. I mean if I have an RCA 7025 in V1 and a Raytheon BP in V2 and then a couple of sweet tubes for V3 and V4, it would be difficult to say, "Ah the hell with it. I'm going to put Chinese NP tubes in all four positions." I just don't see that happening to anyone that has gotten hooked on using the real McCoy's.
As Joe said, "It's nice having a tube that you know will work in any position." These old NOS tubes just blow away the specs on a new tube and the main thing is they can handle so much more power on the plates. I mean I have looked for over a year for specifications on "any" brand of NP tubes and it just ain't out there.
Well I got all of my tubes in, fourteen in all. Six, Philips-Amperex 12AX7's, four, Philips-Amperex 7025's and four, JAN Sylvania 12AX7's. There were a few bottle rockets, but they all were good, strong tubes. Looking forward to trying some of them JAN's as a V3 and V4 tubes. The way they tested, that would be a good slot for them.
Really anxious to test the P-A 7025's. Two were real stout. Never had them before. If they are anything like the Amperex 12AX7's tone wise, they ought to be a killer V1.
In closing, the same thing applies to NP EL34 tubes. NOS tubes are just flat out better. Some people don't know this, but I post it all of the time. That is, a NOS EL34 can handle plate voltage exceeding 800 volts. I wonder what my Winged =C='s can handle? I'm running one of my 602's with real xf3 Mullards. The other has real RFT EL34's. My TSL122 had Winged =C='s, but I just spent $200 for a set of NOS RFT's for it. It is in the shop, but I left the tubes with them to install.
Have you ever taken a cheap EL34 and held it by the base and tapped it against you open palm? It sounds like a whole bunch of shit is loose in there. A well built EL34 will hardly make a sound if any. Makes you wonder doesn't it? I hear all of these horror stories on the forum were an EL34 turned itself into a ball of flame, or burned up without any warning. When all was said and done, it wasn't anything with the amp. The tube was defective. A NP tube (like a JJ which I'm seeing fail more and more).
I know you can spend 600 dollars or more getting your transformers upgraded. For 300 to 350 dollars (100 watt amp) you can upgrade your power and preamp tubes and you will hear the difference. The difference between the Winged =C='s and the RFT's was huge. Better, tighter bass than before. In the clean channel the amp was almost dead silent and it rang like chimes. In the crunch channel, it was tight and controlled. I was thinking about getting some choke mods done, but after hearing my 602's, I may pass on doing it.
I don't want all my amps sounding the same and I don't think it's possible even if you could make everything equal. I like it that one amp (with certain speakers) sounds a certain way and another amp with different speakers and different pre and power tubes has its own sound. It puts a different smile on your face when you plug in and play.
Marty
