Using EL90/6AQ5 in a audio amp?

[Aleks]

Hi,

is it possible to use the EL90/6AQ5 tethrode for building and audio amplifier and if so, does anyone have some kind of a schematic or an idea for building it ?

Thanks in advance

 

[k7elp60]

Yes it will work as an audio amplifier, about 2 watts of audio out. It needs 6.3V for the filaments and about 250V for the plate. It will also require a output step down transformer to match the output impedance to the impedance of a speaker.

 

[Aleks]

Yes it will work as an audio amplifier, about 2 watts of audio out. It needs 6.3V for the filaments and about 250V for the plate. It will also require a output step down transformer to match the output impedance to the impedance of a speaker.

Thanks for the reply.

I think that I will be able to gather around 4 or 5 of the 6AQ5 tubes, can I arrange them by 2 or by 4 in parallel so I can get some more wattage ?

 

[k7elp60]

I would use 4 of them. 2 in parallel and 2 in parallel with the two groups in pushpull in class B configuration and you could get about 10 watts out of them.

 

[Aleks]

I would use 4 of them. 2 in parallel and 2 in parallel with the two groups in pushpull in class B configuration and you could get about 10 watts out of them.

Thanks again, any chance that you might have a schematic of some source about this kind of an amp ?

 

[Nigel Goodwin]

Thanks again, any chance that you might have a schematic of some source about this kind of an amp ?

There are many hundreds of valve amplifiers circuits on the net, none are likely to use those specific fairly obscure valves though. Biggest problem is aquiring suitable output transformers.

 

[k7elp60]

I agree with Nigel. There must be many power tetrode amplifier circuits on the web. As far as the output transformer is concerned you my do a search for Hammond transformers. As I recall they are located in Canada and still produce audio output transformers.

 

[Aleks]

I agree with Nigel. There must be many power tetrode amplifier circuits on the web. As far as the output transformer is concerned you my do a search for Hammond transformers. As I recall they are located in Canada and still produce audio output transformers.

Thanks guys for the replies. First off all I'll try to get my hands on a couple of more of the 6AQ5 tubes. I've found couple of schematics on the net, so when I have 4 tubes I'll try to design a circuit and then I'll ask for your help again

 

[canadaelk]

Go to Hammond Mfg. - Racks & Rack Cabinets, Small Enclosures, Electrical Enclosures, Transformers, Outlet Strips
There is a lot of tube amp info there, including tech. stuff. Do not miss their antique radio museum.