Prince O' Wails Mod

[Bob M.]

I just completed John McIntyre's Prince O' Wails mod in a Fender Princeton amp I have. This circuit sounds very, very good and I was wondering if anyone has built this amp for themselves and is interested in discussing or exchanging info on tweaks, variations, ect. I'm not really a fan of Princeton amps (but I love Princeton Reverbs) as they are sort of a glorified bedroom amp so I did this circuit and the amp now, for me, is much more usable. The phase inverter provides enough drive so you can really push the 6V6s. This amp has a very sweet, smooth distortion sound. I mounted a EVM 10-L Series II speaker in this amp that I had around. I will eventually tweak some values to my own playing style but out of the box, it sounds really nice. I have in the past built a couple of Bluesmaker circuits in Bassman heads for clients and that is also another very nice McIntyre mod. I really like his soft clip circuit.

Bob M.

[sliberty]

I just completed a Princeton Amp (AA964 circuit) sans vibrato. I'd be very interested in any mods you have. The amp seems to hvae almost no power at all, but maybe thats what happens when you have a 12 watt clean amp. it starts to sound nice when it is up at around 7 on the volume pot, but even then, its very clean. The cleans are nice mind you, but the amp may not be very useful to me in this form. A little more balls is in order for sure.

I'd love to hear about your amp, both before and after the mods. Do tell...

Steve

[Chuck_Farlee]

Prince O' Wails documents from Steve A.'s Blueguitar site:

http://www.blueguitar.org/new/articles/other/pow.zip

chuck

[sliberty]

Thanks Chuck, very much.

[Steve A.]

I just completed a Princeton Amp (AA964 circuit) sans vibrato. I'd be very interested in any mods you have. The amp seems to hvae almost no power at all, but maybe thats what happens when you have a 12 watt clean amp. it starts to sound nice when it is up at around 7 on the volume pot, but even then, its very clean. The cleans are nice mind you, but the amp may not be very useful to me in this form. A little more balls is in order for sure.

I'd love to hear about your amp, both before and after the mods. Do tell...

Steve

Before you give up on your Princeton build (no reverb either?) you might want to try a few tweaks I did to my PR: a Type 2 MV with a 100k to 250k dual ganged pot replacing the 220k bias splitters, and a mid boost control (I like to bypass the tone stack with a 0.01uF cap run through a 2M pot, from the plate to the wiper of the treble pot).

Maybe the non-reverb Princeton works different from the PR, but I can get all sorts of nice and dirty sounds out of mine...

Steve Ahola

[sliberty]

Hi Steve - thanks for the reply.

The Princeton Amp doesn't have the gain makeup stage that the Princeton Reverb has (after the tone stack). So it is a different animal, at least slightly. Otherwise essentially the same.

I was thinking about bypassing the tone stack, and your description of a .01 uF cap to the treble pot wiper is what I had in mind, but what is the 2M pot abouit? Gain reduction? Can you show me a schem snippet for this?

Thanks,
Steve

[sliberty]

Man - I have bypassed tone stacks before, but I have never seen this much of a gain increase from doing so. The tone stack looks pretty normal, but it is just sucking the life out of this poor amp. With it bypassed, the amp has real guts. its not even that it gets very distorted - it doesn't (well a little). But it just gets MUCH louder and fuller, to a greater extent than I have seen before.It does get a little arer too though - I might have to tweak that a bit.

[Bob M.]

Princeton/Princeton Reverb

I don't think a Princeton is much of an amp. The power tubes aren't really driven hard enough. Based on my very good experience with John McIntyre's great POW mod, I would re-build any Princeton I got my hands on to the POW circuit but, at the very least, copy the POW phase inverter and you'll have a real amp on your hands. As an absolute minimum, one do the Stokes Mod to the PI of a Princeton amp.

The Princeton Reverb on the other hand is a real amp (two extra 12AX? tubes). I do think they have too much distortion for certain types of music and then you have to deal with the PI once again. Getting the PI right with either model is essential if you're gonna move beyond nostalgia. This is the main (gain) difference between these amps and higher-up Fenders.

[Steve A.]

Hi Steve - thanks for the reply.

The Princeton Amp doesn't have the gain makeup stage that the Princeton Reverb has (after the tone stack). So it is a different animal, at least slightly. Otherwise essentially the same.

I was thinking about bypassing the tone stack, and your description of a .01 uF cap to the treble pot wiper is what I had in mind, but what is the 2M pot abouit? Gain reduction? Can you show me a schem snippet for this?

Thanks,
Steve

The 2M pot is wired as a variable resistor in series with the cap, so that you can adjust the amount that the tone stack is being bypassed. Look at the Blackface channel of the Kendrick Climax amp for an example of that. Or look at it as a Dumble PAB (pre-amp boost) but with a pot wired in series...

[tubedood]

Old post I know but if this is still having interest I also liked my POW Prince o Wails build. Hopefully there's others that have some input/experiences in this build. I'm eager to build another and any tips on layout design would be a help as mine wasn't too crafty but I think a revisit to the build I'd do better this time! PS Nice to meet you folks I just joined here and am already digging the site!
Dale

[darkbluemurder]

No experience with the POW mod, only with McIntyre's BluesMaker mod.

[tubedood]

I've seen that Bluesmaker schematic it looks interesting . Might have to try that one sometime also!

[Chuck H]

I really like his soft clip circuit.

Got a schematic?

We're all familiar with the swap to LTP for these amps, but what is this "soft clip circuit" of which you speak?

[tubedood]

Hi Chuck... here's the Schematic for the Prince O' Wails modded Princeton. The soft clip is over on the power tubes cathode. It does make a noticeable difference in the amps behavior. I tried this circuit years ago and am getting ready to try her again this time under the guidance of this forum! (Hope this time i succeed HaHa)

Dale

[eschertron]

The switchable cathode resistor - AKA soft clip - will give a gain boost relative to the unbypassed cathode R. I can see this changing the relationship between preamp clipping and power amp clipping, but which is which?

The pot that varies the grid reference from ground to a little closer to the cathode voltage is new to me. When the cathode bypass cap is in, I can see it functioning like a bias control on a fixed bias amp (sorta). With the bypass cap out, it's a little more like additional NFB?