Blackface Princeton - get the power section working hotter

[skyboltone]

Thanks Andy, I knew there must be a reason for everybody going to the schmidt/LTP. I knew about the unity gain bit but didn't know you couldn't just drive it harder.

[dartanion]

When driven too hard, is it swamping the PI or the power section with the 0.1uF coupling caps? Going down to 0.022uF caps helps with the swamping bass farts. I've driven my 5E3 pretty hard with boost pedals and such and it doesn't fart out with the cap change. It would fart out on its own with the 0.1uFs.

[Andy Le Blanc]

restricting the bandwidth helps...... and increasing the bias resistor.....
but then you limit the amps application..... starts to get away from the
vender foodoo..... its something to keep in mind
we tend to uphold the tube stuff with a reverent awe... but it has design limits
split load types are limited as far as power handeling
long tailed inverters are self balanceing but they do it with feed back
which makes it practical for a low maintanence circuit but again has a gain
restriction as well as balance issues..... and all that feedback, it can be
argued that its as much of a hindrance as savior..... any way

I remember hearing some where that scooping the guts out of old princetons
and cramming in as much iron as would fit around the speaker basket was
where boogie started...... to address the same issues

the cathodyne or concertina or split load I found a refferance that calls it a
chathode- loaded and "kangaroo" type

[sliberty]

You can also brown the sound by using a 5V4, 5U4, or 5Y3 to lower B+ and as a result lower plate voltage which gives you earlier breakup.

Hope that helps.

I happen to have a few of thes different rectifiers laying around, and wouldn't mind a bit more breakup from my amp at all. Overall volume level is not a concern to me as this is an "at-home" only amp for me.

Any down sides to this substitution?

[dartanion]

Well, you really need to be cognizant of filament current of the rectifier as a 5U4 draws 3 amps and a stock Princeton PT will most likely fry.

The biggest thing that you can to open up the tone is to put in an NFB bypass switch. It'll be louder and much more raucous. I pretty much never use NFB in my builds unless it's necessary. It's a simple very reversible mod if you want to try it.

[sliberty]

It looks like the 5Y3GT stays in the 2A range for its hgeaters, but can only deliver 125mA. Is that sufficient? I am thinking it is, since a Tweed Deluxe uses a 5Y3. Am I missing something?

[dartanion]

The Princeton is running higher plate voltages, but so long as your biased correctly, it shouldn't be a problem.

[BluzMike]

I have had no problems with 5V4s in PRs and tweed Deluxes. But I actually prefer the tone with the standard 5Y3, as it is more transparent and open.