tube B 406 triode dick's cleo 4

[suwaned]

please help and advise : i will building preamp cleo 4 with B406 but i want used my OT line Hashimoto 10k for replace Cap.
how to calculate and where i must connect this OT line? replace R catode or replace cap end circuit? sorry i 'm newbie and this my first experience.

http://www.triodedick.com/cleo_4/cleo4%20copy.gif
thank you dick's

[the_manta]

There are better ways to use your 10/2.5k - 600R line out transformer. The clue is the B406 triode here which only has µ=6. Thanks to µ-follower operation the real amplification factor will also be around that value. Your transformer has a voltage/current ratio of Sqrt[10^4/600] ~ 4. So your total amplification is only 6/4 = 1.5. With the 2.5K taps the total amplification is around 3.
Now it's up to you if such a low amplification does make sense for you.
You can go the parafeed way and put the transformer after the cap instead of the 470K resistor.

BTW: You don't have to use the D3A here (which prices are rising) every high-gm pentode will work here. 12HG7/12GN7 are available for like 1$. The D3A shows its potential primary when connected as triode.

[suwaned]

Originally Posted by the_manta

There are better ways to use your 10/2.5k - 600R line out transformer. The clue is the B406 triode here which only has µ=6. Thanks to µ-follower operation the real amplification factor will also be around that value. Your transformer has a voltage/current ratio of Sqrt[10^4/600] ~ 4. So your total amplification is only 6/4 = 1.5. With the 2.5K taps the total amplification is around 3.
Now it's up to you if such a low amplification does make sense for you.
You can go the parafeed way and put the transformer after the cap instead of the 470K resistor.

BTW: You don't have to use the D3A here (which prices are rising) every high-gm pentode will work here. 12HG7/12GN7 are available for like 1$. The D3A shows its potential primary when connected as triode.

hank you verry much The_manta.

this time i already have :
tube B406
D3a
rectif telef AZ1 mesh.

my transformator: Hashimoto PT220R and line out transformator 10 K

i did to build :
supply filamen for D3a i used AC 6,3 volt pararel direct fron main transformator.
supply filamen 406 i used DHT filamen 2,5A from guido (tent labs) in put ac 5 volt 3A x2 --- i hope can adjust to 4 volt-- bacause when i will trial this supply can not to adjust to 4 volt and constant out 5 volt ---- this my problem -- my friends tell to me for inser resistor before to adjust the trimer -- i not yet trial.
my friend ever build this but more hum. and PS must have supply 10 volt for get 4 volt fixed and low hum.? How the result if i do not use the circuit current sourse like triodick's?
until now i have not turn on because i fear....
how do you think about my work?
thank you again

[the_manta]

I just copied the specs from hashimoto website so that everyone knows what we're dealing here:

Primary: 10K Ohms - Secondary: 600/150 Ohms
Frequency Response (+-2dB) 20-45,000Hz
Insertion Loss: 0.7dB
Rated DC Current: 15mA - Max. DC Current 35mA

How the result if i do not use the circuit current sourse like triodick's?

The Result would be less gain and a bit higher distortion, but 100% pure triode distortion, so don't be afraid.

Because your Line Output Transformer can tolerate DC-current (rated for 15mA) you could just build a standard common cathode amplifier. But amplification would decrease to A = µ(10k/(10k+Ri)) where Ri is the inner resistance of the B406 which is 4.5k. This yields A=~4.1. (The 2.5K taps can't be used here, since that is a too low plate load and distortion rises greatly)With the ratio of the line out transformer there wouldn't be any gain at all ! This would just be simple buffer stage. So that's no solution

Let me point out the problem: You have really nice (and for sure expensive) parts here. But you can't combine them for a good result. Either you take Triode-Dick's ciruit and use your tubes or you go for another circuit with other tubes and use your nice Hashimoto line out transformer. If you want some amplification in your preamp, you can't combine these parts you have.

Your Power Transformer is a bit oversized for a preamp:

380V-320V-0-100V-320V-380V: 0.2A
0-4V-5V: 3A ( x 2)
0-6.3V-10V: 2.5A
5V: 3A

This baby could be used for a whole stereo power amplifier instead !

Well, you have to decide what you want, as I said there is no really good way in combining those parts.

[suwaned]

dear The_ manta
my power tranformer right for power amplifier,
I had no choice, because I bought this with the view of the secondary SPECIFICATIONS who can approach required from the power transformer from the circuit triodedick's.
I am looking for transformer preamp but no it's the tango or Hashimoto.
I have some pictures that I take may be seen to be in correction.
may be i wrong.....


inside preamp B406 | Flickr - Photo Sharing!
preampB406_triodedick's | Flickr - Photo Sharing!
inside preampB406 full | Flickr - Photo Sharing!

[suwaned]

for now I again tried to connect the line out transformers on the cathode of the B406 in parallel Rk by eliminating capsitor end and 470K resistors.
Rk I subtract the DC resistance of the line out transformers?
I do not know if this is true? What amplification? I can not count
like you said:amplification 1.5.
I seem too extravagant, but I want to make a well for a preamp I can use forever.
I have not tried parafeed, to assist in the circuit with a line out transformers have a low tone of voice.

[the_manta]

I don't know if you could follow my post from above
I just made a picture of the three variants which could be arranged:

for now I again tried to connect the line out transformers on the cathode of the B406 in parallel Rk by eliminating capsitor end and 470K resistors.
Rk I subtract the DC resistance of the line out transformers?

No, there is no sense at all to connect the transformer with the cathode of the B406. Amplification will be less than 1 ! You just made a very bad cathode follower this way.

I enjoyed watching the photos though
Nice collection of transformers (Tango, Hashimoto)

[suwaned]

sorry I was wrong. I mean the line out transformer from the plate B406.
This scheme --- sorry bad picture.
I am glad I have a lot of knowledge from your Manta


thanks for viewing pictures

[suwaned]

Originally Posted by the_manta

I don't know if you could follow my post from above
I just made a picture of the three variants which could be arranged:





No, there is no sense at all to connect the transformer with the cathode of the B406. Amplification will be less than 1 ! You just made a very bad cathode follower this way.

I enjoyed watching the photos though
Nice collection of transformers (Tango, Hashimoto)

thank you Manta , already given me Cleo4 scheme with the line transformer, I've tried to scheme 1, but there is a hum and then I scaled it with the added R 10K parallel line out T----- (5K ----- I do not know what really counts) --- hum is reduced, but here I just give B + 340v anode D3a------- Anoda + B406 : 70 volts. is this correct calculation? I do not understand. how much i must give B+ because my main transformer380- 320-0-320-380 ( i used 320-0-320) you are correct , I have tried my schema ---- fault __no sound . thank you verry much MANTA +++++ AAAAA

[the_manta]

Hi !
I'm glad to hear from you again.
I did not quite understand where you put the additional 10K resistor. But let's see about the hum first:
The B406 must be heated with DC, especially in a preamp. I hope you could adjust the heating voltage to 4V. The D3A should work with AC heating it was used for telecommunication systems and often with AC heating. But you can test that: connect the D3A heaters to a switch and when the amplifier is working (and humming) than open the switch for a short time (1-2 sec) and listen if the hum disappears. Don't do that for too long because the D3A can only handle 400V across cathode - Anode/G2 in cold(not heated) condition.
When the hum disappears, the AC heating is the problem !
If not, the Anode Voltage might be a problem. Here you can do same. Just switch of the High Voltage and the amplifier will work some time with the voltage coming from the capacitors.
Last problem could be the stray-field of the transformers. Your Power transformer can induce a field to the interstage transformer. You can test that very simple: Does the amplifier hum when you connect the output directly to the capacitor as it was intended in the original circuit ?