My new 71A project

[MartinV56]

Hi Guys, tomorrow is a holiday here, I began build the Set 71A
I am using an old chassis SE-84 manufactured at the end of 60.
Adequacy of the chassis for the valve 71A, DHT 4-pin socket, 0.8 watts of power, plate voltage 180V, voltage filament 5v

Transformers audio Impedance 5K, secondary: 4,8,16 ohm

Transformer Force original amplifier, 300 0 300V, Filament 6.3v, 5v for use by rectifier EZ-81

Choke: 5H 120mA, 120 ohms

Drivers: 6CG7 Twin Triodes middle gain, amplification factor 20mu, Noval, electrically similar to the 6SN7 but Noval in order to build sockets drivers installed in the chassis.

I think this will dwarf the consent of my Set

[markus]

NICE ! .8 watts of blistering power :thmbsp:

will this be used with your Altecs & EV tweets listed in your signature ?

are you going to utilize the volume pot / balance / tone controls from the 'donor' chassis as well ?

I still have a couple nice RCA 71A's I want to use for a flea power amp, but first I need to finish my DIY 45 SET . . . but FIRST I need to get my dremel tool repaired so I can finish cutting holes in my chassis for my oil caps . . . :D

[MartinV56]

Thanks Markus, Yes, I am going to use with Altec, and I dismantle the network of tones, bass, treble, balance, scracth, rumle, I use only the chassis of an old console. The project is build a typical Single Ended Triodes but in the chassis of an old console, perhaps using the site such controls, the hum balance, I think it's a good idea. The 45 is a great valve, excellent in all frequency ranges with low profound bass inviting hear jazz and R & R in 2watts

[markus]

are those the factory output transformers from the console ?

I've got a rather beat-up Heathkit AA100 that I may scavenge the OPT's from for my SET project . . . turns ratio shoul dbe close enough, and it has multiple taps (4, 8, 16 ohm) as opposed to my current repurposed OPT's which have only 8 ohm taps . . .

[MartinV56]

Yes, are the original Single output transformers for the console, 5K, 4/8/16 ohms.

[MartinV56]

So go

[MartinV56]

So go, with the 71A amp

[MartinV56]

I only say,WOW,great valve and great sound

[markus]

very cool that this 71A project came out so well for you :yes:

have you been able to experiment with different brand 71A's and 6CG7's ?

I've got a good smattering of 71A's (RCA, Arcturus, etc) that I'm dying to try in a good circuit . . .gotta finish the family / listening room renovation first before I can mess with the toobs again :D

[MartinV56]

Thanks, 71A are Tungsol and 6CG7 are sylvania, is a Karlson the enclousure in your avata?

[jaymanaa]

Thanks, 71A are Tungsol and 6CG7 are sylvania, is a Karlson the enclousure in your avata?

The RCA cleartop version of the 6CG7 is also very nice, as is the RCA Black plate with sheild between sections.

[markus]

Thanks, 71A are Tungsol and 6CG7 are sylvania, is a Karlson the enclousure in your avata?

yes it is (a pair actually) :D I got them from Sixcats! a while back, and finally found drivers worthy of them - Altec 417's . . . I use them for < 100 Hz duty for my DIY line arrays - so far the Karlson / Altec combo is the only one that keeps up with the line arrays . . .