My first tube Amplifier VT4C DIY record

[asterkao]

Toy11 VT4C 211AMP -1

images-1.jpg
Start to prepare the components and box.
After estimate the box is not big enough for two channel circuit and components.
So decide to make Mono-Mono Amplifier.


images-2.jpg
Estimate the placement for good signal quality and easy hand make.
High voltage must keep long distance with small signal circuit.


images-3.jpg
Final estimate placement picture.
Double check rear panel placement.

[asterkao]

Originally Posted by asterkao

Toy11 VT4C 211AMP -1

Attachment 207216
Start to prepare the components and box.
After estimate the box is not big enough for two channel circuit and components.
So decide to make Mono-Mono Amplifier.


Attachment 207217
Estimate the placement for good signal quality and easy hand make.
High voltage must keep long distance with small signal circuit.


Attachment 207218
Final estimate placement picture.
Double check rear panel placement.

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[singa]

Hi, Your transformers are exposed ( no covers) so be careful if you have
small children or pets around including yourself. This maay be a difficult project. Can you post your schematic? Let us know of your progress.
Good luck. Singa

[asterkao]

Hi Singa :
Attach schematic for your reference.
Did your ever DIY VT4C before?
images-4.JPG

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[singa]

Originally Posted by asterkao

Hi Singa :
Attach schematic for your reference.
Did your ever DIY VT4C before?
Attachment 207243

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Hi asterhoa,
No I have not diy 211/VT4C but I have one pair.No budget/money
for it. I have one pair of cheap Hammond GSE125 10K ohm output for non hifi use,so I am quite familiar with big transmitting tube like 211,845,805.
( How difficult to make good sounding amplifier).

I see you are using 6C45 as driver,not that it does not work but as you know 6C45 can oscillate and the luck of the circuit?. (if you don't use grid stopper resistor).I have friend who diy 211 pushpull(6C45 driver) with Tamura outputs not too bad but I feel can be better.

Since you have not start assembly maybe you may want to consider using
another DHT like 2A3 or 300B as driver because only a big tube can give the
required current when VT4C/211 needs it (transients) plus the quality of signal.Or at least use pentode like 6L6 or EL34 wired as triode.

If you can try using AC heater ( afraid of hum?) for 211/VT4C as it will give a more emotional flavour to the sound.( kan cheuh in chinese).Have you heard of Sakuma? Visit his website at "direct heating" and find out.

Also use oil caps(motor run type) instead of electrolytic caps for power filter?

But since you have already bought all your components you will probably
use them anyway.Wish you good luck on your project. Singa

[Vinylsavor]

Hi!

The 6C45 is a poor choice for a driver tube IMHO. It will offer no headroom and will dominate the sound of the amp. I wrote an article about my view on this topic:

VinylSavor: Gain, Headroom and Power

Best regards

Thomas

[danFrank]

I don't like the RC coupling to the grid of the 211. Use a cathode follower driver or mosfet driver for better handling of the 211 grid. Look at the Ongaku schematic.
Daniel

[asterkao]

Originally Posted by danFrank

I don't like the RC coupling to the grid of the 211. Use a cathode follower driver or mosfet driver for better handling of the 211 grid. Look at the Ongaku schematic.
Daniel

Thanks for your suggestion.
Did your had ever hear Ongaku 211 before?
How about the Ongaku 211 sound color?
If your have Ongaku 211 schematic Pls send to me...thanks!
They fully hand mark all component like silver resistor, silver capacitor even silver transformer..... that's really out my ability.

http://tw.myblog.yahoo.com/jw!9frLFy...T_geG5fC24WQ--

[asterkao]

Originally Posted by Vinylsavor

Hi!

The 6C45 is a poor choice for a driver tube IMHO. It will offer no headroom and will dominate the sound of the amp. I wrote an article about my view on this topic:

VinylSavor: Gain, Headroom and Power

Best regards

Thomas

Thanks for your reply.
After check ....
spec. 6C45Pi plate-resister only 930ohm, gain-factor about 52.
spec. 5842/417A plate-resister 1.8kohm, gain-factor about 43.
So I choice 6c45pi.
Because I don't like soundcolor of 6sn7,12ax7,12au7 there are also have big plate-resister too and I want try somthing different.

AsterKao

[asterkao]

Originally Posted by singa

Hi asterhoa,
No I have not diy 211/VT4C but I have one pair.No budget/money
for it. I have one pair of cheap Hammond GSE125 10K ohm output for non hifi use,so I am quite familiar with big transmitting tube like 211,845,805.
( How difficult to make good sounding amplifier).

I see you are using 6C45 as driver,not that it does not work but as you know 6C45 can oscillate and the luck of the circuit?. (if you don't use grid stopper resistor).I have friend who diy 211 pushpull(6C45 driver) with Tamura outputs not too bad but I feel can be better.

Since you have not start assembly maybe you may want to consider using
another DHT like 2A3 or 300B as driver because only a big tube can give the
required current when VT4C/211 needs it (transients) plus the quality of signal.Or at least use pentode like 6L6 or EL34 wired as triode.

If you can try using AC heater ( afraid of hum?) for 211/VT4C as it will give a more emotional flavour to the sound.( kan cheuh in chinese).Have you heard of Sakuma? Visit his website at "direct heating" and find out.

Also use oil caps(motor run type) instead of electrolytic caps for power filter?

But since you have already bought all your components you will probably
use them anyway.Wish you good luck on your project. Singa

Thanks for your suggestion.
Your have one pair of VT4c/211 is a good start.
I think your better keep enough distance for 211 and don't too close other component because 211 is very hot and Output transfermer is a key to effect sound color.
I had ever hear about 5 sets sound color of pushpull 211 and sound not goog so I make a choice to design Single-End 211.
I choice 6C45pi base it's hi-gain factor.
Your mention about afraid of hum.... this must trad-off.
My speaker sensivity about 97db after test distance 25cm almost not hear hum I could accept it. ....just as your say ..more emotional flavour to the sound.
Power use C-L-C filter type to genrater high voltage but the cap. is not oil cap.
First C use 3 pcs of Spreque 40uf/600 cascade to 1800V.
Second C 4 pcs od cap. cascade to 1800V.
Because I setup VT4c working in 1250V (Spec. Max. voltage).
images-5.jpg

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