Other Amps

RI Princeton question

1

So I get a nice RI black panel Princeton Reverb, have it tweaked with Jensen Neo, standby switch, line out, and kool tilt back legs.

The idea was to have one guitar in each input. But I forgot 2nd in put is way less loud... I assumed that would be an easy fix my amp guy is saying it's never done. This sorta kills the reason for getting this set up anyway.

The idea was to get away from A/B box etc. Has anyone ever gotten input 2 up to same input level as input one?

3

Vintage silverfaces were set up like that too.

4

One of my many rules, like no single 8s or 10s, not more than two floor stompboxes of any sort, is also no single input amps-- they should be illegal. So Blues Jr. etc. all that stuff not allowed In My World. Maybe time to dump this and go boutique shopping.

Although I didnt' get an explanation, I can see why they did it back in the days when a mike might also go in, but why this can't be changed to even input levels -- I don't get that.

5

Supro. Many of their new amps have dual inputs, they stay loud and clean too. Ignore the jumped channel thing, I never use that. Whenever I do, I just think...that sounds annoying.

6

Input 1 was for single coils such as a Fender. Input 2 was for instruments with higher output such as humbuckers. The idea was to equalize them. If you have a single coil and an HB guitar try them that way.

7

Have you tried plugging in two guitars? With both inputs used you should bypass the voltage divider of Input #2 (LO) and the two inputs should be the same. I used to do it when there was just one amp. Doesn’t sound great, but it works.

8

Input 1 was for single coils such as a Fender. Input 2 was for instruments with higher output such as humbuckers. The idea was to equalize them. If you have a single coil and an HB guitar try them that way.

– Don Birchett

I was guessing it was for a mike -- wondered if this was from the start of 1960s amps, or further along in the evolution of the design.

9

Have you tried plugging in two guitars? With both inputs used you should bypass the voltage divider of Input #2 (LO) and the two inputs should be the same. I used to do it when there was just one amp. Doesn’t sound great, but it works.

– Powdog

Well I will try this since thaat was the idea all along -- have both plugged in together. How does it degrade the sound?

10

Dang Powdog is right .. when both are plugged in it makes them even, but at the lower level .. works for me since I am never over 5

11

This actually makes me curious how many people run their pedalboards into input 2. I did it a long time ago and I'm about to switch back to input 1 to see why I started running it on 2.

12

The problem with a Y cable is that when one guitarist turns down his volume....both guitars go down in volume....because the signal of both guitars is grounded through that one guitarist's volume pot.

13

These schematics show the three input configurations available on the PR and many other fender amps. Note that the arrow on the right goes to the input tube grid.

With only input 1 connected, it is a high impedance (1 Meg) input. In this case, the 68k resistor has little effect apart from creating a low pass filter with the tube input capacitance.

With only input 2 connected, it becomes a voltage divider (1/2) with a lower impedance (2 x 68k = 136k). The attenuation is nominally 6 dB, but in fact will be more than that compared to input 1, because the impedance of the source (pickup and circuit) will add to the upper 68k.

With the two inputs connected, it becomes a rudimentary mixer where the 68k resistors provide some isolation between the two instruments.

Recommendation:

Input 1: passive instrument

Input 2: active instrument or pedal (low output impedance)

Input 1 and 2: active instruments or pedals.

14

I'm not sure about the theory that the Hi input was meant for single coils and the Lo for HBs... Fender were building amps with Hi and Lo inputs way before Gibson came along with the PAF. Most tweed amps have Hi and Lo inputs. I don't know why but I guess they never knew what people would plug into their amps!

16

Shouldn't a dynamic mic need more gain than a guitar pickup.....not less?

Some of my older amps have the low gain input marked "accordion" since an electric accordion's output was (is) greater than a guitar pickup.

Gibson Les Paul amps have 4 inputs with two marked microphone (hi-gain) and two marked instruments. (lo-gain) AC30s had a hi and lo gain input for each of their 3 channels (six in all)

Remember, it was common for bands back then to only be able to afford one amp so everyone plugged into it.

17

In the early days, they'd be likely to use a piezo/crystal mike. Dynamic mikes came out later, but have a lower output than piezos.

18

I went back to my PRRI 65 user's manual. Here is what it says:

So, using input 2 input stage gain will reduce distortion.

19

Well I am selling it anyway... it's too damn heavy @ 35 freekin pounds with a Neo speaker even

If Mojo cab were significantly lighter I might look into that.


Register Sign in to join the conversation