12AU7 Amp?

[thefragger]

I apologize if this has been covered before (I did try to search for a thread!) but could one make an amp using only 12AU7 tubes in class A or AB? or are they not powerful enough to be more than an linestage amp...

hmmmm........

[Kashmire]

12AU7 is capable of pushing 5-8 mA of current. A Broskie Aikido with 12AU7 would make a mighty nice linestage.

[aardvarkash10]

if you have a 125db/w capable speaker, anything is possible...

[Tubes4e4]

Hi,

Originally Posted by thefragger

I apologize if this has been covered before (I did try to search for a thread!) but could one make an amp using only 12AU7 tubes in class A or AB?

Sure, f.e have a look at Tim Williams' "Hept'AU7" amp. If you want to go all 'AU7, you also can replace the driver 6SN7 with 'AU7 with little modification, if any.

http://webpages.charter.net/dawill/t...Hept%27AU7.gif

Regards,

Tom Schlangen

[Kashmire]

I've been wanting to mess with the JJ ECC99 for years, but haven't found a good reason to try them. In the back of my mind, I've been picturing a headphone amplifier.

So instead of a zillion 12AU7 valves in parallel, how about some 6CG7? Take another step up (in size and power) and use a bunch of ECC99? Filament current would probably be an issue!

The 6CG7 is one of my all-time top favorite valves.

Either way, a bunch of small triodes in parallel with an EL84-style transformer will work. Edcor (and several other companies) make a 7.6k : 6 output transformer that would be great with a handful of ECC99.

[HollowState]

Tim De Paravicini got 20 watts per channel using only 12AX7s (10 per channel) in his V20 intregrated amp.
Stereophile: EAR V20 integrated amplifier
http://www.blackdahlia.com/tipindex/...3/tip__13.html

[rotaspec]

It would be great to be nearby when the US military scraps those old triode based supercomputers. Imagine all those ECC tubes

Gary

[jerluwoo]

Digging up this thread since it made me curious if a decent little amp could be made with au7's, and it doesn't seem as if the op got a decent answer. I used a maggie console amp 197-10 as the platform, originally a stereo EL84 amp. It has a 300 0 300 transformer with 5v and 6.3v taps, using the original 5y3gt rectifier and the small current draw of the amp netted a B+ of 320v before the rc filters. The OT's are 5.2k/3.2 ohm units, and I use a pair of pioneer cs-g203 speakers with a 6ohm nominal impedance,although strangely all the speakers in it are stamped 8ohm. I get about 1 watt out using both sections of the au7's in parallel in single ended fashion with about 295v across them and about 8ma current per section. It sounds quite good although a little lacking in the low end bass.

[yagas]

jj ECC99 or 6H30 are more suitable

Hagerman Technology LLC: Cymbal Vacuum Tube Push/Pull Power Amplifier 6H30 6W DIY Kit

[Tubes4e4]

Hi,

what´s the purpose of R7 and R8? Intended as grid stoppers? If so, just connect pins 2 and 7 with a wire as short as possible at the tube socket and use a single grid stopper of about 1,5...2,2k Ohms.

Regards, Tom Schlangen