Monica 2 and the grounded grid

[praveen77]

Yes, I used a choke too, although didnt try the tuned choke approach as mentioned by yeo. My PT is the same as Pete and i run it through schottkys ($2) --> 8uF oil caps --> 30H/40ma Hammond choke --> 47uf Solen

I am using AC filaments, with two equal resistors (50R) between the ends and tapping a 0.1uf cap to ground from the center of the two resistors. The whole thing is DEAD silent for 93db speakers.

Praveen

 

[praveen77]

Pete,

Thanks a lot for your suggestion regarding the halo getters ... i just installed them and highs are significantly better. Glad I decided to try them.

Praveen

 

[Peter Menting]

Praveen;
Glad they worked for you. They seem to remove the "haze" from the high end bringing it into focus. Don't know any other way to state it, but the improvement is worth the money and comes without adding additional components to the circuit-----a "twofer"!

Pete

 

[buble_corp]

-> Praveen, Peter
Thanks for your reply. I'll probably order PSU filter choke L=12H R=350Ω I=50 mA, 2 plate chokes L=75H R=1000Ω I=20mA and power transformer U2=250V/200mA, U1=6.3V/2A from local producer http://www.ogonowski.eu .

 

[pengboon]

I've built my GG for Monica but I get plenty of noise coming out. With only heaters and no B+, the sound is fine (like no GG), as soon as I turn on B+, the noise comes out, left channel more than right, swapping tubes left and right doesn't help. Currently using Amperex, maybe too microphonic? Power is CRCRCRCRC, DC filaments, 120H plate chokes. Would a PSU choke help? Could be my layout? can someone who has done it sucessfully post a pict of the underchaasis for me to have a look?

 

[Peter Menting]

What kind of noise? Hiss? Hum? -----one thing comes to mind, if you floated the filaments, then run a cap to ground it kills any hum.

Never could figure how to post a picture to this forum---E mail me and I'll attach what I've got to the response.

Pete

 

[pengboon]

It's hiss, somewhat like when the radio is not tuned to any station...

Have mailed you Pete. thanks for your help.

 

[buble_corp]

Hi,
I built GG for Monica2 using 6Z9P tubes (russian E180F equivalent). I didn't use choke in PSU and used 10k resistors on plates. I've got 120V on plates, and anode current running through plate resistors is about 8.5mA. What plate current value do you have?

 

[buble_corp]

For encouragement my finished GG for Monica2 with 6Z9P.

 

[buble_corp]

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[buble_corp]

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[alexg]

I had the 6688 GG for monica2 built, sounds great, but the gain is still lower than my other sources (CD and DVD Player).

How do I bump the gain?

I was using Amperex and it is so microphonic that I have to put the GG and Monica on the floor away from the speakers.