10 watt Fender Deluxe

[Mikante]

Hello guys,
I know i have another post about this project but the question i have is really something on its own.
First of all i decided to simplify this build, i making it like the early deluxe ab763 but with no tremolo.
Keeping the third tube for the ltp and each channel will have two dedicated gain stages, no interaction was my goal in the first place.
I m getting to my question now. Is it possible to have this design running like a 10 watt princeton? They are pretty similar apart for the two channel. Maybe using the ab763 power transformer but the princetone output?
The schematic, the drop resistors needs to be set on the run. I can not predict what the solid state rectifier will supply.

6DFF977A-2308-4D3E-B23B-13C6825054DC.jpeg

Id like to keep it on the low wattage side. I was first looking at the 5e3 but i really don t want the two channel to mess with each other.
Second i like better the voice of the scooped tone stack.

[Stevem]

What are you using for a power transformer?

Dropping out 8 to 10 watts of output like a Bf Deluxe has to start with will be hard if your plate voltage is over 350.

One fix regardless of the recto used would be to add another power supply node that trims off the unneeded voltage age, your preamp node power supply dropping resistors would then have to be played with to get back up in plate voltage.

You might also look into turning up a pair of 6K6GT output tubes since they are a drop in for a 6V6, but are rated for only 8.5 watts and not 12.

Another help in dropping the B+ Voltage would be to cathode bias the output stage.

[Mikante]

Thank you very much.i could use the princeton power transformer, i just don t know if it will be enough to drive two separate channels and a ltp. In this regard, i m having trouble finding information.
The princetone iron is 320/320 90ma and has no 50v for the bias. This i know

19A3BEBF-F4A1-49AC-A64F-6A94F4D91FD8.png

Looking at the schematic, fixed bias and cathode phase inverter seems to me the biggest difference.
I could use the power stage layout from the princetone?

[Rogan]

Thank you very much.i could use the princeton power transformer, i just don t know if it will be enough to drive two separate channels and a ltp.

The Princeton reverb has 4 preamp tubes, with one being the reverb driver (a small poweramp, using significantly more current than a regular gain stage). The Deluxe (no reverb, no trem) has just 3 preamp tubes. A Princeton Reverb transformer would have plenty of current for your original design. As long as a power transformer has enough heater current, it can drive virtually any number of preamp tubes. Each preamp gain stage only requires something like 1mA.

You could use the Deluxe LTP phase inverter, but use the bias circuit of the Princeton Reverb. If you want slightly less power output, you could make it cathode biased like the 5e3.

[Phil_S]

What are you really trying to do? The 5E3 is about 15W. The perceived difference in loudness between 10W and 15W is very small. To perceive a meaningful drop in power, I suggest you'd need to go below 5W and maybe as low as 2W.
If you want 10W, just go for it. I'm just saying, before you go to the trouble of making a custom circuit, have an idea of what to expect.

[Mikante]

Thank you very much.i could use the princeton power transformer, i just don t know if it will be enough to drive two separate channels and a ltp.

The Princeton reverb has 4 preamp tubes, with one being the reverb driver (a small poweramp, using significantly more current than a regular gain stage). The Deluxe (no reverb, no trem) has just 3 preamp tubes. A Princeton Reverb transformer would have plenty of current for your original design. As long as a power transformer has enough heater current, it can drive virtually any number of preamp tubes. Each preamp gain stage only requires something like 1mA.

You could use the Deluxe LTP phase inverter, but use the bias circuit of the Princeton Reverb. If you want slightly less power output, you could make it cathode biased like the 5e3.

Cool, exactly what i had in mind, 2 pre amp tubes and a ltp. For the bias, if i use the princetone power transformer i can t use the ab763 arrangement anyway cause it does not have a 50v out.
I just need to couple the ltp from the deluxe with the power stage of the princetone reverb.

What are you really trying to do? The 5E3 is about 15W. The perceived difference in loudness between 10W and 15W is very small. To perceive a meaningful drop in power, I suggest you'd need to go below 5W and maybe as low as 2W.
If you want 10W, just go for it. I'm just saying, before you go to the trouble of making a custom circuit, have an idea of what to expect.

Hello, maybe i got you confused, 10 watt or close to it is my goal. The deluxe ab763 is way too loud for my purpose as it goes above the 20 watt range.

[sluckey]

For the bias, if i use the princetone power transformer i can t use the ab763 arrangement anyway cause it does not have a 50v out.

You don't need a 50V bias tap. Just get the ac voltage from the high voltage winding like the princeton does. You only need to change one resistor to use the AB763 bias circuit.

[Mikante]

Yes i noticed, i thought the princeton reverb had a fixed bias design.

[maxkracht]

Yes i noticed, i thought the princeton reverb had a fixed bias design.

BF/SF Princetons are fixed bias, so are BF/SF Deluxe. Fixed means a fixed DC bias voltage on the control grid that is, confusingly, much easier to make variable than cathode bias, the other most common option in a power amp. Tweed Princeton and Deluxe are cathode biased.

[Mikante]

Yes i noticed, i thought the princeton reverb had a fixed bias design.

BF/SF Princetons are fixed bias, so are BF/SF Deluxe. Fixed means a fixed DC bias voltage on the control grid that is, confusingly, much easier to make variable than cathode bias, the other most common option in a power amp. Tweed Princeton and Deluxe are cathode biased.

It is always fixed once you find out the right value
Anyway, for fixed I mean a resistor, not a pot.

[sluckey]

The princeton has a NON-ADJUSTABLE fixed bias circuit. And it's further complicated by the bias vary tremolo circuit. I never suggested using the princeton bias circuit. This is what I said...

You only need to change one resistor to use the AB763 bias circuit.

[Mikante]

Didn't you tell me to use the prineton bias design?

[sluckey]

Didn't you tell me to use the prineton bias design?

no

[Mikante]

The princeton uses the high voltage out and different values but it is still adjustable. I m not a fan of cathode bias so I don t see any other option.
I mean turning it into a variable bias with a 10k pot.

[Rogan]

You can use the bias circuit from the Princeton Reverb. Just omit the tremolo and intensity pot. You may have to adjust the value of the resistor to ground to set the appropriate bias voltage.

Or, google for some Princeton mods for adjustable bias.