211 VT-4C Good Simple SE Schematic

[PTSOUNDLAB]

Hi,

does somebody have a good 211 / VT4C schematic like Air Tight ATM-211 to recommend ? If it's possible without interstage transformer and 6SN7 input valve.

I have some, but I would like to have opinion those which used these valve and to share their experiment

Thanks.

Pascal.

[The-Planet]

About the least complex 211 I've seen is the design on PAE's site:

PAE 6C45 --> 211 amplifier

I built a version (with a very different power supply design) with a more modest B+ (825vdc) that I've been enjoying.



Use RF precautions around the 6C45 (grid stoppers, RF beads).

- Gary

My website....

[PTSOUNDLAB]

Thank you very much Gary.

Does somebody have schematic of Atarashi Parafeed 845 amplifier ? It is a 845 drive by a 6CA7 and i think it would be interesting with 845 and KT88.

Thanks

Pascal.

[The-Planet]

I think this is the schematic you're looking for:

6CA7 --> 845

- Gary

[Miniwatt]

Has anyone built this amp? I'm quite curious about it... I like it's simplicity:

About the least complex 211 I've seen is the design on PAE's site:

http://digilander.libero.it/paeng/6c...ation_page.htm


@ Gary / The-Planet : What is your version of the power supply??


Thanks

[gaborbela]

Hello
Can someone let me know if I can replace the 211 tube with GM70 type?
I know I can replace 845 with GM70 if I adjust the heater voltage. GM70 use 20V for filament.
I have a nice 211 schematic "Goliath" but I want to use GM70 power tubes.
Greetings gabor

[the_manta]

211: µ≈11
845: µ≈5
GM70: µ≈6

Is that the right schematic ?
http://www.triodedick.com/goliath/go...versterker.GIF

Than you can't use it. The 27/56 doesn't have the ability to drive the low-µ GM70.
Rough calc: Ub≈1000V -> GM70 has to control 2000V with a mu of 6 -> you have to deliver a Vpp of 2000/6 ≈ 333Vpp

Vpp from the driver in the schematic is too low.

[gaborbela]

Hello

Thank you for youranswer.
Yes that is the schematic. I know these tube hard to drive..
Many people drive the GM70 with D3a tube. Get about 17-20W power.
Here not tha D3a tube is the drive of the GM70??
Thanks one more time.

Greetings gabor

[Vinylsavor]

Hi!

The D3A is a poor choice as a driver IMHO, way too little headroom. While the possibility to get away with 2 stages might be tempting, over simplyfing things can be a bad compromise. Yet it can be done with 2 stages

Here is my approach to a 2-stage 211 amp, not very simple, but good

VinylSavor: Making of a 211 Amplifier, Part 1: Planning

Thomas

[gaborbela]

Hi
Thank you very much.
I see U use inter stage transformer. I would like to avoid to use one.
There are many design with 2 stage with out inter stage transformer. Some people say the D3a would be the best choice.

Many of these tubes have a plate resistance
about 2Kohm but only the D3A and 6C45
have an amplification factor greater than 50
D3A specifications in triode connection:

filament voltage: 6.3V
filament current: 315mA

Max plate voltage: 200v
Max plate dissipation: 4.2w
Max cathode current: 33mA
Plate resistance: 1.9Kohm
Amplification factor: : 77
Max resistance in grid circuit: 0.5Mohm

6C45 specifications:
filament voltage: 6.3V
filament current: 440mA

Max plate voltage: 150v <<<<< it is lower than D3a
Max plate dissipation: 7.8w
Max cathode current: 52mA
Plate resistance: 1.2Kohm
Amplification factor: 52 ±16 <<<<< selection is necessary
Max resistance in grid circuit: 0.15Mohm

Inter electrode capacitance:
input: 11±2 pF
output: 1.9±0.3 pF
transfer: 4.5pF

Greetings