100V EL34 Push-Pull tube amp

[nashkato]

i got this EL34 PP amp with 100 Volt outputtransformer with feedback winding .

can i replace the OT with a regular 4-8-16 Ohm OT without feedbackwinding ?

the ratio pri to sec. FB is approximately 1:88
main sec. ratio : 1:4

 

[metalockpick]

Almost everything can be modded.

If you don't have tertiary windings or special taps the circuit needs to operate, then yes, you can. Even if you do, there's more than one way to skin a cat.

Guitar amps are different from Hi Fi gear. Use the appropriate part for your intended application.

 

[abbey road d enfer]

i got this EL34 PP amp with 100 Volt outputtransformer with feedback winding .

Usually, NFB from a dedicated winding results in lower distortion and improved fequency response.
It is not common to see that in a 100V system, taht typically uses poor quality loudspeakers.

can i replace the OT with a regular 4-8-16 Ohm OT without feedbackwinding ?

It is possible. You have to make a choice, either using NFB from the low-Z secondary (of course you will need to adjust the value of the FB resistor, and maybe add a capacitor for fighting instability/oscillation), or run the amp withpout NFB, which results in higher distortion and different dynamic response.

the ratio pri to sec. FB is approximately 1:88

Seems unusually low. Can you draw a schematic that would show how NFB is applied?

main sec. ratio : 1:4

Seems about right. The amp should deliver about 50W, that's a load impeadnce of 200 ohms on the 100V output. With a 1/4 ratio, that makes the primary 3200 ohms, which is about correct.

 

[nashkato]

Seems unusually low. Can you draw a schematic that would show how NFGB is applied?

 

[abbey road d enfer]

The gain from the input to the FB winding is about 22.
An 8 ohm secondary delivers a voltage 4.4 times higher. That means you would need to increase the NFB resistor from 1k to 4.4k, or whatever is nearest.
Of course you'll need to adjust it in view of the possibly different output xfmr you finally use.