Replacing ECC83s with EF86s ?????

[BenjiJuanKenobi]

I hope someone of the forum can help me with a technical issue. Steve Dawson, if you can't answer my questions I am sure someone at Marshall can.

I was lucky enough to obtain one of the English-made AC30HW combos made in circa 2002. It has only 1 channel (with a high and low input) and 5 ECC83s in the preamp.

I have been told part of the great sound of the 60s AC30s comes from the EF86 in the preamp. After hearing some amps that use this tube, I am inclined to agree. Can I just take out the ECC83s and put EF86s in their place? Are the sockets the same? Do I have to have any of the circuity modified? Do any settings need to be adjusted? Do I have to replace all of them?

You guessed it. I am not that technically savvy, so your help is appreciated.

[surfnorthwest]

EF86 is a pentode tube and 12AX7 is a triode tube. EF86 has higher gain. They have different pinouts so they are not interchangable.

An EF86 amp will get very loud before breakup.....in fact the EF86 was developed as a HI fi tube and was used on the front ends by several 1950s hi fi manufacturers. They have a reputation for being microphonic and hissy, but they have a unique sound. Dr Z sure likes them, a lot of his amps use them.

[SteveD]

I

hope someone of the forum can help me with a technical issue. Steve Dawson, if you can't answer my questions I am sure someone at Marshall can.

I'm insulted.

Can I just take out the ECC83s and put EF86s in their place?

Absolutely NOT

[BenjiJuanKenobi]

I

hope someone of the forum can help me with a technical issue. Steve Dawson, if you can't answer my questions I am sure someone at Marshall can.

I'm insulted.

Can I just take out the ECC83s and put EF86s in their place?

Absolutely NOT

Sorry, no insult intended.