Randall RT2/50 Question

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photios

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The Randall RT2/50 has three 12AX7's....what are they for and what type of 12AX7's should I use in those 3 positions to get things quiet and have a lot of clean headroom?
 
One for each sides EQ, the middle is the PI.

I ended up with NOS JAN Phillips in mine, your ears may tell you different.

Robert

photios said:
The Randall RT2/50 has three 12AX7's....what are they for and what type of 12AX7's should I use in those 3 positions to get things quiet and have a lot of clean headroom?
 
I bought mine used and it has EH 12AX7's in all 3 spots...I've always found the EH 12AX7's to be really high gain and not to my tastes at all. I've always preferred the 12AX7-C chinese preamp tubes...they seem to have a lot of top end sparkle and low gain...perhaps I'll give'm a go.
 
The middle one is the input stage for both channels, the two outside tubes are the phase inverters for the respective channel.
 
So they color the tone? I thought a power amp was supposed to be about accurate reproduction of what it is being given, without distorting? So if I buy this I need to worry about what 12AX7s to put in the power amp?
 
Sure. The real main reason to have a tube power amp is to color the tone and intruduce a little power amp tube saturation. This is what makes them good for guitar. Otherwise we would all just use a solid state crown power amp or something. Know what I mean? :wink:
 
I thought it was to amplify or otherwise optimize the volume of the signal. For instance, when re-amping and such. I thought it was explicitly supposed to reproduce what it is being given, adjusting for output tube characteristics? That's why power amps are made with a gazillion watts, no? I'm not used to 12AX7s in my power section.
 
To really appreciate what a power amp like the RT2/50 can do, you owe it to yourself to read about the history of guitar amps, especially in the origins of rock and roll and blues guitar. It was the sound of the entire amp, the little tubes, the big tubes, the speakers, the transformers, the amps circuit, the wooden box it was in, etc. You get the picture. The concept of a "straight wire with gain" is fine for accurate reproduction of sound that is already recorded. It would make a terrible guitar amp. The amplifier is as much a musical instrument as the guitar you plug into it. Hope this helps! Pat L.
 
Oh, I know. When I look at an amp, I take into account the power section. That's why I've got 3 amps with power scaling - to get the power scaling working for me. Hunter's books on the history of guitars and amps and the combination thereof are my favorite.

However, when separating them and putting them in a rack, or when using a rack power amp in a slaving or reamping scenario, I thought there was supposed to be a difference. That is, they were supposed to reproduce what they're told to reproduce, with as much headroom and as little coloration as possible.

Perhaps the RT2/50 was meant to be mated with the RM4, and is supposed to be 1/2 of a regular old amp, just in rack form.
 
Tube power amps aren't meant to accurately reproduce what's put in them. If they were, then we'd all be using Crowns or huge PA power amps so we had clean power, right? Here's a good example - take a line 6 pod or the equivalent, play it into a Crown or Peavey CS800 or whatever power amp you have handy that's used for sound reinforcement - in other words, a cleaner/flatter poweramp. Heck, try a studio poweramp.

Now plug into a tube poweramp, and I guarantee you will like the tube amp better. Why? Because it colors the sound. Same reason why guys like to record on analog tape vs digital - it colors the sound and is more pleasing to our ears.

The RT 2/50 sounds great with other preamps too - I ran an ADA MP1 into mine for grins and it sounded really awesome. Yeah, that 12ax7 is an amp stage in the front end, but the other two 12ax7s HAVE to be there to drive the power tubes. If it sounds good, it is good. I wouldn't sweat the details.

Pete
 
Maybe I'm approaching this question wrong.

I'm already going to have a fully formed amp signal coming from a slaved amp - Mesa Mark or TOV. So I'm already getting the benefits of a tube preamp section and a tube power section.

Next, I just want to modulate the volume, and convert it into the proper signal to drive a speaker cab. This is what DeMartini did when he slaved his good sounding Marshall into a regular old Marshall for more volume. And Metallica did it slaving a MKIIC+ into an old Marshall.

I guess I could always bring the slaved signal from my Mark or TOV and put it into my Peters, which has a power scaled power section. That way I'm just dealing with power tubes (which I of course know color the sound even when not distorted), not more 12AX7s. The RM2/50 just seemed convenient.
 
You do realize that even if you plug into *any* tube power amp, your signal is still going through at least one 12ax7, right?

Pete
 
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