I have a sunn amplifier that is kind of HIFI ish and i am modding it a bit so I want to change the ultralinear mode to "normal". How would I do this?

I understand just take the screen power leads from the output transformer and put them aside making sure they dont short anything. Then conenct the screen grid on the tube to a screen voltage supply. Where could that be?

 

Don't know whatt a "sunn amplifier" is
Don't know what HIFIish means
Explain the difference between ultralinear and "normal"
The screen power leads from the transformer are AC.
You seem to be saying you want a fixed DC voltage on the screen grids -- is that correct?

 

Don't know whatt a "sunn amplifier" is
Don't know what HIFIish means
Explain the difference between ultralinear and "normal"
The screen power leads from the transformer are AC.
You seem to be saying you want a fixed DC voltage on the screen grids -- is that correct?

Yeah I just know that to wire it how I want I just disconnect he ultralinear taps and power the screen grid with the screen voltage supply. Where is that

 

Why?
You want to make it less HiFi?

 

Why?
You want to make it less HiFi?

Yes. I am going for a rock and roll sound. I have made other mods and do not want the sterile clean sound. Less hifi

 

You're going to need 'golden ears' to notice the difference.
Perhaps get a guitar effects unit and feed the amp input from that, then you have control over how bad you want it to be.

 

You're going to need 'golden ears' to notice the difference.
Perhaps get a guitar effects unit and feed the amp input from that, then you have control over how bad you want it to be.

Having the ultralinear tap adds feedback to reduce distortion. Just how do I do it please haha

 

You need to know what voltage to apply to the screen grids. You need to know how to design pentode/beam tetrode output stages (whichever kind of valve it is. Once you know what voltage you need, then you need the schematic to work out where and ow to get that voltage.

Or, we could guess, connect the screen grids to the centre tap of the transformer primary.
I am not to be held responsible if your amplifier releases the magic smoke.

 

You need to know what voltage to apply to the screen grids. You need to know how to design pentode/beam tetrode output stages (whichever kind of valve it is. Once you know what voltage you need, then you need the schematic to work out where and ow to get that voltage.

Or, we could guess, connect the screen grids to the centre tap of the transformer primary.
I am not to be held responsible if your amplifier releases the magic smoke.

The voltage should be about 450 on the plate. How do I find the screen. And here's a schematic

 

The screen grids are marked with red arrows and the centre tap is marked with a green arrow. Incidentally they are pentodes not beam tetrodes.

 

The screen grids are marked with red arrows and the centre tap is marked with a green arrow. Incidentally they are pentodes not beam tetrodes.
View attachment 126867

I meant, how do I find what the screen voltage should be? And how do I convert it

 

Tube datasheet. Tube manual.

 

Tube datasheet. Tube manual.

va: 450
vg2: 375

screen is 375 so. where do I get this 375 volts to power the screen with. Non ultralinear

 

Is the amp......original? If not...I have no suggestions......read tube manual and output transformer spec.

If the amp is original........restore to spec........before modifying.

I would also recommend not to modify amp. The effect you are looking for comes from the power supply design....not the amp.

Just my 2 cents.

 

The points A,B,C, and D at the bottom of the schematic are various DC voltages

 

The points A,B,C, and D at the bottom of the schematic are various DC voltages

Soo. Just go off of the one closest to 350.

 

The points A,B,C, and D at the bottom of the schematic are various DC voltages

Do I just take a wire off the terminal of the cap or what

 

So just in steps. How can I achieve this. I want to change it from ultralinear mode which is more hifi to "normal" without the ultralinear taps.

 

Yeah I just know that to wire it how I want I just disconnect he ultralinear taps and power the screen grid with the screen voltage supply. Where is that

How am I supposed to know that without a schematic....
Never mind I see the schematic.

Since that supply is unregulated, I'm sure you can do what you want to do and get the behavior you expect. I can't read the drawing that well; what other points are A, B, C, and D connected to? It is possible that supply will just collapse if it has unexpected loads placed on it. Also the resistors separating the points might need some work as well. What are the values and the power ratings?

 

How am I supposed to know that without a schematic, or a picture, or a set of crystal balls!

The schematic is above and here's a pic. Excuse the Snapchat haha