• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Ongaku

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Salut Du Bonnieure,

I have an Ongaku Schematic without the values either, but the B+ feeding the 211 says 860V. If you neglect the DC resistance of the primary winding of the output transformer, you could calculate the max current the tube could draw. With newer 211 (75W dissipation limit) that will put the maximum current at the operating point around 87mA or so. Older tubes had a dissipation limit of 100W and therefore the max quiescent current value would be around 116mA.

This is all a "back of the envelope" calculation, but if you lack the real values, you could get a rough estimate like this. It will be an overestimation.

Take into account that the same secondary winding is used to feed one half of the 5687 tube with 460V also, so find out the max possible current that tube can take at 460V and you have another maximal estimation. Add up everything and voila!

Cheers,

Rada
 
Ex-Moderator
Joined 2003
Welcome to the forum du bonniere.

I don't want to rain on your parade, but if you're not able to determine how much current a SE 211 amplifier needs then I have doubts as to your ability to safely construct something using 860V. There are no degrees of death, but you just don't get a second chance with 860V, whereas an error with 300V will cause a few sparks but possibly not much more. Could I humbly suggest that it might be better to gain some experience by building a SE 2A3 amplifier before progressing to 211?
 
Hi,
It is not my first amplifier but the overone was KIT. No problem for 1000V, because I work every day with 400V. A power transformer is expensive and I want to be shure.
Here is my estimate:
5V, 10A ( 2A*4 5AR4 Ih)
12V 2A ( 0,5*2 Ih 5687+0.2*2 Ih 6072 )
10V, 5A ih211
10V, 5A ih211
150V,0,6A because 2*0,3A max
380/0/380 V, 300mA (2*120Ma max 211 current + 2*90Ma max 6072 current)
Are you OK
Thanks for your help
bruno
 
Welcome Bruno,

I think it might have been mentioned here before, but I'll mention it again...
Above 500 or 600v things start to behave differently. Things you thought were good insulators seem to fail (such as the sheaths of components). The voltage rating of most resistors is exceeded. Sparks start to jump a visible distance.

Be very careful:att'n:
 
Hi, my Ongaku is finished.
You can see some pictures here: http://fr.pg.photos.yahoo.com/ph/dubonnieure/album?.dir=/f78e&.src=ph&.tok=phIiSWDBNL91cYOw
There is no problem, no noise. I have just to change a 5ar4 that i have broken
:(
The sound is warm and powerful, very realistic.
About the power transformer, the good way for 5AR4 is not just one output 5V but 4*5V with a good isolation ( 1500V mini). You have characteristics of my transformer in the pictures.

goodbye
 
Easy.........

Take that tube current from other posts & include the other tubes as well. With a choke input filter, the transformer can deliver close to the AC output current rating, but with a capacitor input, derate to 60% current. After this excersize, add a minimum of 25% reserve capacity for good regulation of the B+ (high voltage).

A tube rectifier will add series resistance, so find the PSU Designer II power supply simulator at Dungan Amps site to target the power supply voltage. I find the simulator fairly accurate.
 
Hi,
To really finisched my ongaku I want to have good tensions.
I now 860V. But are the other values good?
For example to have –50V (-50 is the good value), It is not
–200V but – 165V.
Are 460 and +200 the good values?
Is somebody knows the good value for the pin 1 of the 6072 and for pin 1 and 9 of the 5687?.
Thanks
Bruno
 
Tensions.


Angel.
 

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Thanks,
Sorry, “tension” is voltage.
Here is my mail: clairf@infonie.fr
I have the schematic with –200, +200, 860, -50 and 460V.
860 and –50 are good but it’s not possible to have –200 and
–50V with my schematic. In my ongaku, to have –50, I have changed the value of the 500 Ohm ( the good value is around 1K but my 211 are not WA and the current is not the same).
So, if this value is not good, I think: are the other values good ?
and I would like to have the best value. For exemple, I had good sound with 440V for 460 and 156 for +200????? But I have to do other tests.
If you have the best values for the sound, I would be happy to test.
Thanks
 
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