12au7 valve alternatives

[Michael London]

Hi.

Has anyone tried changing their pre amp valves from 12au7 (ECC82) to an alternative type such as the 6SN7 or CV181 in their integrated valve amplifiers? What were the results?

Cheers

 

[vacuum_tubes]

You can't just replace an ecc82 with a 6sn7 as you could cause damage, (a) they draw different amounts of current and (b) it depends how they are being used to drive the circuit.

Stick with using different makes of 12au7/ecc82 as there are so many to play with. Long plates are nice.

 

[Locheeboy]

Used a fair pile o’ different valves, over the years. Have a PrimaLuna Dialogue Premium preamp atm. All 6 preamp valves are 12AU7 slots. Original equipment was PrimaLuna 12AU7s Silver Label (Shuguang, specially selected by PrimaLuna ). They check all the valves, keep 60% of them , return the rest. They were and still are , good valves.
Ah moved onto - all Sylvania substitutes for 12AU7s.
58140, 6189, Gold Brand versions of these .Tried Mullard-they were - to me, lost in space, muffled, their purportedly fabled mid band was (IMO ) carried by my PrimaLunas. Didnae like them. Telefunken, again, don’t like them - shrill.
Japanese flirtation with Toshiba (12AU7s )Matsushita - 5814WA, still have them in my power amps.Good tubes.
Then the scales fell from my eyes, the cloth from my ears, new taps for my toes …the fabled…
CBS JHY 5814WA. My search was done. IMO the finest preamp tubes ever made .They now fill the 6 spots on the front of my Dialogue Premium. They’ll die there.
Musta cleaned them out as cannae find ANY, anywhere on the web, and ah have visited some out of the way places, searching for valves.

Have not heard new Russian or East European new tube that I would want to buy…yet.
Ah’d recommend sticking to tried and true (as above) never especially, cheap and cheerful ex - computer valves, they sound atrocious.Cheap but nasty.

 

[vacuum_tubes]

I've just received some RCA 5814wa but haven't tried them yet, loads of them available online at 'fairly' reasonable prices.

 

[Barrymagrec]

You may find the 6SN7 is a bit of a tight fit in the socket....

I have heard it said that the 6SN7 sounds better but I think it would depend on the particular circuit.

 

[Locheeboy]

You may find the 6SN7 is a bit of a tight fit in the socket....

I have heard it said that the 6SN7 sounds better but I think it would depend on the particular circuit.

Don’t ye need an adaptor for the 6SN7 into a 12AU7 base? Haven’t heard a 6SN7 but as it’s the grandad (more or less)
of the 12AU7, ah would expect it to be outperformed by its grandson but…as ye say it may be system dependant.

 

[Barrymagrec]

Don’t ye need an adaptor for the 6SN7 into a 12AU7 base? Haven’t heard a 6SN7 but as it’s the grandad (more or less)
of the 12AU7, ah would expect it to be outperformed by its grandson but…as ye say it may be system dependant.

Yrs, I was being facetious but as the 6SN7 is so much larger than the 12AU7, plus an adaptor it would be impractical in many cases. If your 12AU7 is connected for 12 volt heaters as is a sensible option anyway you would need a 12SN7, or if you had a series 300mA heater chain.

If you are talking grandad valves the MHL4 from 1929 is the predecessor to the 6J5 / L63, the single triode version of the 6SN7 / B65.

 

[vacuum_tubes]

Those adaptors drop the 12.6 to 6.3 for the 6sn7 but the current could still be an issue, also you can run a 12au7 on 6.3v by using the heater centre tap and running the halves in parallel.

The 12au7 is not a great voltage amplifier compared to the 6sn7 which also has lower distortion (this is why this is more common in 300b circuits)

Personally I wouldn't switch a 12au7 for 6sn7 at all, the amp designer chose 12au7 for a reason and you are undoing that.

 

[Big John]

Don’t ye need an adaptor for the 6SN7 into a 12AU7 base? Haven’t heard a 6SN7 but as it’s the grandad (more or less)
of the 12AU7, ah would expect it to be outperformed by its grandson but…as ye say it may be system dependant.

The 12AU7/ECC82 was not particularly good in my system I tried other valves I tried 12BH7 found them inconsistent. American forums suggest best is a 6CG7 with the internal plate second a 6FQ7 without plate both 6.3v.

Since the 6CG7 is the 9 pin offspring of the 8 pin 6SN7. With the approval of Mark the Ming (Mark Manwaring White) of Ming Da for my Ming Da MC7R pre using adapters I fitted a pair of Chinese Military 6N9P T metal base tubes that Mark gave me very effective, so good in fact that I fitted a pair of Russian 6N8S as well. I also did this to my power amp using my PSU powered adapter & 8 pin adapter for a pair of Reflector 6N9S tubes to protect the amps transformer. A pair of 6N8S using adapters complete the amp.

As has been said the heater current is higher for 6SL7 & 6SN7 The MC7R circuit had it's origins using 8 pin valves so no problem. The external PSU solves the power amp problem as it did when using 6CG7's.
Oh the sound is good coming out of my OTA Quad 57's would be reluctant to go back to 9 pins. I even replaced the 12AU7/ECC82 follower in my Croft phono stage rewired to take a 6N1P the Croft is fitted with a bigger transformer.

 

[GT]

The 12au7 is not a great voltage amplifier compared to the 6sn7 which also has lower distortion (this is why this is more common in 300b circuits)

Not sure why you would say the 12AU7 is not a good voltage amplifier. If you are looking for an amplifier valve for a low gain circuit then the 12AU7 is perfectly good, assuming you are using an NOS type. They are also good for a cathode follower stage. Any distortion you mention would not be audible if the circuit the valve was used in was correctly designed. I am not saying the 12AU7 is the best sounding low gain valve, but it is certainly no slouch in a good circuit. If you need higher gain then there is the 12AT7, 12AY7 and 12AX7.

 

[vacuum_tubes]

Voltage gain of the 12au7 is not as linear as the 6sn7.

Don’t have anything against the 12au7 it is after all a 6sn7 with 10 years of development thrown in. Personally I generally prefer the sound of a 6sn7 in 300b circuits but I do have an amp that uses a 12au7/300b and sounds fantastic.

 

[GT]

Personally I generally prefer the sound of a 6sn7 in 300b circuits but I do have an amp that uses a 12au7/300b and sounds fantastic.

If you are using a 12AU7 to drive a 300B in a 2 stage design then you are using the wrong valve. You will need more voltage gain to drive the 300B grid plus more current than the 12AU7 can provide.

 

[vacuum_tubes]

it's a rather unique thing works well in my setup as I have a very very high gain preamp and 107dB horns

Don't use it very often but it does sound fantastic (it's direct coupled based on the loftin white circuit)