Question(s?) about transformers

Hi there!
I got some questions about transformers, especially the Carnhill.
I got some spareVTB 2280 transformers, 600/600, 1+1:1+1.

Can I use them as substitutes of  VTB1148? If I read the datasheet:
VTB1148: 1+1:1.7+1.7, wired in serie primary secondary (like 1073 output) the ratio is 200/600 with +4dB gain
VTB2280: 1+1:1+1, if wired parallel primary and serie secondary, the ratio is 150/600 with 6dB gain

If I use them in 1073 clone or 2254 for example, the only difference will be the gain output? (2dB)

Xformers are sometimes obscurs for me... I know the output Z reflects the input Z...

Take a look on VTB 9045, used as interstage in 2254, wired serie/serie, 1+1:2+2. Can I use a 2280 here?
VTB9046, used as input in 2254, serie/serie, 2+2:1+1.... Can I use a 2280 revrsed here?

I know you can't swap output xformer with input xformer because of bias current, but  what about swapping input with output?

Thanks for help

mrdarwin said:

I know you can't swap output xformer with input xformer because of bias current, but  what about swapping input with output?

Thanks for help

Click to expand...

It depends on the device, your goals, and the specific transformers you are using. Input transformers for mic preamps in particular tend to have higher nickel content than many output transformers you might have on hand. Nickel has higher permeability than steel, making it easier to excite the core at lower voltages (like those a mic puts out). If you swap in a low nickel content output transformer (or an all steel core), you’ll tend to get less low frequency response at the lower voltages encountered at the input of the device. Also, if the output transformer core is large, you may not get enough voltage passing through it to adequately excite the core, and response will suffer.

So it depends. For a line amp, it won’t matter as much as for a mic preamp.

BT

Ok, thank you for this precise answer.
So now I know why  there are "input" and "output" xformer.

About the ratio difference between 1148 and 2280? Only gain change? Serie or parallel wiring does change the sound?

Ratio bewtween this transformers isn't much different, so output neither. Higher ratio differences sound different because of changed load to circuits. I wouldn't expect much sound difference in so small ratio difference, if impedances and transformer design for each wiring are correct.
Both transformers are gapped which means they can take DC current through them. This is quite rare today, a lot more common is parafeed where capacitor blocks  DC to transformer primary winding. That makes a lot bigger difference to the sound; such designs can have quite "bad" specifications although some sound excellent. Old Neve are good examples of gapped output, it would be interesting to hear how it sounds with some nickel in the core.

Thx for these infos