yagoolar's tube amp projects

[yagoolar]

Progress photo

 

[tcqanh]

Does anyone take comparision on the sound of C3g between triode connection and penthode strap ?

my friend just finished his C3g-6B4G SE ampli. He said to me that C3g in triode with G3 connect to anode get better sound than G3 connect to kathode, sound become sweeter and more dynamic. He asked me why, but I cannot explain it. Has anyone got this experience ?

 

[yagoolar]

tcqanh,

Have you read build log to which I attached link in post 48?

 

[yagoolar]

Input switch done and tested. Now it is time to connect and fire the amp.

An externally hosted image should be here but it was not working when we last tested it.

 

[yagoolar]

 

[djn]

That is a beautiful amp and I really LOVE those meters. Where can I get a pair of them???

 

[yagoolar]

That is a beautiful amp and I really LOVE those meters. Where can I get a pair of them???

Those are USSR NOS stock one can find on same flea markets in Poland. And golden rings comes from Ikea.

Thanks for your kind words about the amp.

 

[yagoolar]

C3g is dead. Time for E180F

One C3g is dead. Why have I not tested it before? No spare item. Bad luck. I have EF861 (E180F) or 6c45pi. Will use pentode strapped pentode.

 

[tcqanh]

One C3g is dead. Why have I not tested it before? No spare item. Bad luck. I have EF861 (E180F) or 6c45pi. Will use pentode strapped pentode.

1 Tube C3G Siemens Post Rohre | eBay

You can consider 4P1L with the same socket to C3g. This tube has low gain, so you need more 1 stage at input.

 

[yagoolar]

1 Tube C3G Siemens Post Rohre | eBay

You can consider 4P1L with the same socket to C3g. This tube has low gain, so you need more 1 stage at input.

I bought mine for $3.00 a piece. They were used yet matched. After I had looked through ebay.com I decided not spend this much money on C3g. I have EF861 by hand (E180F equiv), which is also a good tube for the project. Less aesthetically pleasing, but E180F or 6Ж9 are easily available in Poland, prices starting from $1.50.
3-stage amp is a different project. 4п1л has too low μ as triode, so I'd rather keep it for output or driver tube in future projects.

 

[Stixx]

You have PM

 

[yagoolar]

The board for E180F pair.

An externally hosted image should be here but it was not working when we last tested it.

 

[audiogenesis]

In case you're interested, I just finished an amp using a C3o (6.3V version of C3m) running resistor loaded as a pentode, cap-coupled to 300B.

 

[yagoolar]

In case you're interested, I just finished an amp using a C3o (6.3V version of C3m) running resistor loaded as a pentode, cap-coupled to 300B.

Better looking than mine. Congrats!

 

[yagoolar]

I miss something and sorry for not reinventing the wheel - I used EF861 instead of C3g. Specs read Ug1=+9V, while there are schematics of preamps with this tube as an voltage amp + driver biased with cathode resistor. And Ug1 is set to -2.5V In respect to cathode. Is the latter correct?

 

[yagoolar]

Question answered, after I had taken curves.

 

[yagoolar]

I cut open aluminium cover of C3gs - both glass bulbs were broken.
Fortunately new E180F has come this evening

 

[yagoolar]

Where am I going wrong?

The trace comes from E180F anode, 10V/div. Input signal 0,7V RMS.

 

[yagoolar]

I used yellow LEDs for cathode bias. Vg1 measures 1.9V both tubes. Anode DC voltage is 145V and 147V. If I read the trace properly, tubes goes into cut off. Right?

 

[yagoolar]

Fired the amp with E180F BJT CCS and 6C4C

Still things to be corrected, yet fine results right from the start.

There is no resistor in the cathode - I used yellow LED which gives 1.9V, so needed additional voltage drop due to lack of proper model.
MPSA92 is replaced with F241.