311T (211 alike) HIGH power triode

[firefart_1st]

wat can i do with a pair of 311T that i have got around ?

i like stereo but with these tubes i dont get much or can i get more that 20/25W ? with any wierd circuit ?

i'm planing on push pull but i'm kind of in the air with it.

cos on one datasheet o read 260W on push pull ah that is really too much :P
they both work cos i tested them... they were the best sounding half watt cos they were runing on 300V or so...



any ideas ?

tankx in advance

sorry bad inglish...

[Miles Prower]

If those 311Ts are like 211s, you can get almost 20W out of them. So you could build a couple of monoblocks. The only "wierd" part of the circuit is the 1250Vdc that you'll need to feed 'em.

You could also take a good LQQK at Tubelab's 845 design. That'll work.

[firefart_1st]

just one thingy... dont i need to drive these tubes with almost 4W ?do get de full power ? i cant find the datasheet as the moment. and a can advance that these tubes have 100W of plate dissipation

[kevinkr]

If they are truly equivalent to the 211 in class A you will need about 120vpp at no more than a few mA to drive them. The 211 is comparatively easy to drive compared to the 845 which requires substantially higher (about X3) drive voltages for class A.

The driver stage only needs to be able to deliver substantial power levels if you are aiming at class A2 where heavy grid current flows for a substantial part of the positive half cycle. For 20W from a 211 or equivalent this isn't an issue.

Taking a look at the schematic for the Kondo (formerly Audio Note) Ongaku is a good place to start. Lots of people have copied this design and it is good sounding. (I have heard the original and one clone - the Audio Marginal which I also liked.)

Edit: If you are contemplating building a high voltage amplifier, and haven't done it before (and lived to talk about it) there are particular hazards to be aware of. The voltages are high enough that you can't afford to make any mistakes. I used to dread servicing Ongaku's and their kin for this reason. One mistake could leave you... DEAD

Hopefully you are conversant with safe high voltage practice, and have read the safety and high voltage thread here.

At 1.5KV it isn't even necessary in some cases to come in direct contact with a circuit point at this voltage, the field around that point under some circumstances can be strong enough to initiate a dangerous arc from more than several mm way!

I haven't built one so far for these reasons, although I now have a listening room that is inaccessible to prying fingers, and pets so I may proceed in the future.

You might also consider one of the low power amplifier designs running these at around 600V - not safe, but a lot safer, unfortunately power output <5W typically.

[Miles Prower]

Originally posted by firefart_1st
just one thingy... dont i need to drive these tubes with almost 4W ?do get de full power ?

You would need that kind of drive capability if you were intending to operate in Class AB2. If you want to use them for SET monoblocks, then you'd go Class A1 with them. In that case, all you'd really need is enough drive to supply the current to charge up Ci + Cmiller + Cstray, plus a little extra for transient clipping.

So what're you gonna do with them?

[firefart_1st]

at the moment they are gonna be resting on a box :P
i dont have much money to get all the part for an amp like this.
and not really happy with the schematics that i have and the supplyers...
in some time ill make an amp... maybe a 20 watter :P
i don't know yet...
i might do an fancy look amp for show off on my bench :P
in my room ( here i listen to music... etc... ) i hant something diferent.
like 6 chanels of amp's for the DVD 5.1 and for my surround decoder.
bi amp is an later idea ^^ tho frontal speakers bi amped would be OUTSTANDING

and i still havent got a pair of speaker like a dream about.

3 way closed box desing.

i'm looking for good crossovers and not very expenssive ones.

i'm handy with wood and some things more. i have a 40 liters sub-woofer and o dont need much of a HUGE pair of speaker... but stil :P a pair of pioneer old ones dont make me happy.

these tubes stoped wont get old :P much ^^

[firefart_1st]

p.s.:
i'm not affraid of the 1.5Kv psu or anything...

the problem is the cost of that.

i'm carefull in these cases.

it's an amp do make once and hope to be perfect the first time.

any changes to this is not gonna be easy but can be made.

after 3 days the caps maight be totaly discharged with the resistor bleeding them.

e home :P

I NEED MONEY is there anuone with too much money?

i accept check or bank transfer :P

[lndm]

Originally posted by firefart_1st
i'm not affraid of the 1.5Kv psu or anything...

tch tch! (No, you didn't mean it that way, did you )

I NEED MONEY is there anuone with too much money?

Ha! Sorry, I'm married

[firefart_1st]

it was worth the try