Hi everyone!
Well, It seems that I'm approaching the final stadium of the "tube sickness", I'm entering the SE madness...
Once on it, I remember the words of a DIY guy wiser than me: "I never heard an EL84 amp that do not sound at least very good" but also remembered another wise guy saying " God knows that the world do not need another EL84 amp"
So, I was looking around for some simple solution, and from one discussion in this forum, my sight falls over this one:
picture A
Well, I was trying to re- arrange the schematic for my better understanding:
picture B
And there is the arrangement of G3 - R10 (100K) that confuses me, because is very different to others pentode-pentode SE amps (the Mullard 3_3, for example)
It is a kind of local feedback or simply a mistake of my re- arranged drawing?
By the way, I decided for a 6V6G - 6J7G because I want the amp to be full octal tubes (there will be a 5U4G too), 4-5 watt will be enough, and these tubes looks really cool .
I'll be grateful for any advice
Well, It seems that I'm approaching the final stadium of the "tube sickness", I'm entering the SE madness...
Once on it, I remember the words of a DIY guy wiser than me: "I never heard an EL84 amp that do not sound at least very good" but also remembered another wise guy saying " God knows that the world do not need another EL84 amp"
So, I was looking around for some simple solution, and from one discussion in this forum, my sight falls over this one:
picture A
Well, I was trying to re- arrange the schematic for my better understanding:
picture B
And there is the arrangement of G3 - R10 (100K) that confuses me, because is very different to others pentode-pentode SE amps (the Mullard 3_3, for example)
It is a kind of local feedback or simply a mistake of my re- arranged drawing?
By the way, I decided for a 6V6G - 6J7G because I want the amp to be full octal tubes (there will be a 5U4G too), 4-5 watt will be enough, and these tubes looks really cool .
I'll be grateful for any advice
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Thanks, I suspect something like this, but I wasn't sure,... In the doubt I supress the GNF of the original
Nevertheless, I believed that the Shade local FB being plate to plate
Yes it is - that's just regular feedback, but not much of it
.
That two pentode circuit reminds me of another two pentode amplifier.
Mullard 3-3 Three Watt Amplifier
There is a bonus: DC-connected stages. No need for a capacitor between them.
Mullard 3-3 Three Watt Amplifier
There is a bonus: DC-connected stages. No need for a capacitor between them.
Unfortunately not. Some personal and financial issues leads me to stop the project . Hope to restart very soon.
Kevin Connor builded up a similar thing, with great success, and shared a lot of useful info, specialy about the pentode gain stage.
Mine will be different in some aspects.
Last thing I did on this, was a provisory schematic to look at possible ways to inject the partial feedback signal. Nothing other than that. It still remains the tubes to be ordered and to think about the chassis, etc
Here the circuit, but need still a lot of work...
I'll let now here , if any progress
Cheers
J
issues leads me to stop the project . Hope to restart very soon. Kevin Connor builded up a similar thing, with great success, and shared a lot of useful info, specialy about the pentode gain stage.
Mine will be different in some aspects.
Last thing I did on this, was a provisory schematic to look at possible ways to inject the partial feedback signal. Nothing other than that. It still remains the tubes to be ordered and to think about the chassis, etc
Here the circuit, but need still a lot of work...
I'll let now here , if any progress
Cheers
J
Attachments
Oh well, OPT's will be some italian made units that I own.
If there is success, I will try the same units used by Kevin Connor:
http://www.diyaudio.com/forums/tube...havior-w-fixed-bias-se-amp.html?highlight=6V6
These are made by Twin Audio and Kevinkr found that are excellent units..
All the best
J
Yes, these transformers are excellent. The amplifier is quite nice within the constraints and expectations I designed to. Mine is based on a design topology that probably dates back some 60yrs, with a few interesting twists like battery bias on the output stage, and a ridiculously quiet power supply.
Not sure where the reference to Kevin Connor came from since my last name is Kennedy..
mine (temptative)
Sadly, I wasn't able to found a 6J7 LTSpice model nor the famous "cheap red LED" model. So probably there is a lot of un-accuracy, and so in the transformer model, but..
spice file attached, change from .txt to .asc
Sadly, I wasn't able to found a 6J7 LTSpice model nor the famous "cheap red LED" model. So probably there is a lot of un-accuracy, and so in the transformer model, but..
spice file attached, change from .txt to .asc
Attachments
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