Hi,
I have built other peoples designs, but want a go myself. I have a basic understanding of the theory, but a lot of it is pieced together.
Basically, will the following design work?
The css would be borrowed from morgan jones, the output valves could be css biased ala baby huey.
no feedback shown, but i could work it in.
I am new at this, so constructive criticism is very very welcome. my valve choices are what i have in my box.
I have built other peoples designs, but want a go myself. I have a basic understanding of the theory, but a lot of it is pieced together.
Basically, will the following design work?
An externally hosted image should be here but it was not working when we last tested it.
The css would be borrowed from morgan jones, the output valves could be css biased ala baby huey.
no feedback shown, but i could work it in.
I am new at this, so constructive criticism is very very welcome. my valve choices are what i have in my box.
Go to SY's website and read through his desription of the Heretical pre-amp. Sure, its not at all what you are aiming to build, but it is a grerat insight into a detailed design process. I was just blown away by the new to me yet oh-so-obvious considerations that are set out there. It has completely changed how I think about designing ANYTHING...
It would help if you could number the components so that the design could be discussed. Some stuff on there looks not-quite-right, but I don't have you here to point at the screen.😀
sy. thanks forthe advice. I will number the components tonight.
the css is just a better auto bias.
the css is just a better auto bias.
Here is the number schematic
An externally hosted image should be here but it was not working when we last tested it.
Brilliant! Let's start with R11. What's it doing in there? You've got a CCS keeping the two sides of the phase splitter balanced- why not return the grid of the bottom side to the upper grid through a large resistor, then bypass that lower grid to ground? This will give you balance limited only by how well you can match R5 and R6. That also allows you to eliminate C2.
Do you have any philosophical objections to getting rid of R2/C1 and replacing with a diode or LED?
Will the rather high source impedance of the output stage without feedback be a problem with your speakers?
I will not be popular for saying this, but an output stage CCS is not generally a good idea, especially if you're going to clip the amp every once in a while (as we all do, at least all of us who don't have 102dB/1W speakers).
Do you have any philosophical objections to getting rid of R2/C1 and replacing with a diode or LED?
Will the rather high source impedance of the output stage without feedback be a problem with your speakers?
I will not be popular for saying this, but an output stage CCS is not generally a good idea, especially if you're going to clip the amp every once in a while (as we all do, at least all of us who don't have 102dB/1W speakers).
Sy, how is this looking. Re led bias for the first stage, i like it and will have a play when buiilding.
As for the CSS in the output, I have some bias perfboards that i can take from my baby huey and try. I did try the huey without, and it lost something.
clipping.... not in my flat with my neighbours unfortunately!
Feedback, i will apply some and i have shown how, but just to the first stage. I'll have to keep an eye on oscillations.
An externally hosted image should be here but it was not working when we last tested it.
As for the CSS in the output, I have some bias perfboards that i can take from my baby huey and try. I did try the huey without, and it lost something.
clipping.... not in my flat with my neighbours unfortunately!
Feedback, i will apply some and i have shown how, but just to the first stage. I'll have to keep an eye on oscillations.
can anyone help with the css for the differential.
The cathodes will be at high voltage (130 ish) as the stage is dc coupled to the input.
can i use a ring of two? assume i have little to no solid state knowledge, if anyone could help with formulas i would be most appreicative.
The cathodes will be at high voltage (130 ish) as the stage is dc coupled to the input.
can i use a ring of two? assume i have little to no solid state knowledge, if anyone could help with formulas i would be most appreicative.
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would this work
mje340 top, bc547c on the bottom?
An externally hosted image should be here but it was not working when we last tested it.
mje340 top, bc547c on the bottom?
You could use a Ring of Two, but I wouldn't. The cascoded, BJT CCS is way better. You can find an example Here. For this, I used MPSA42's -- a high voltage, small signal type.
It may be 2009, but the modified 5-20 circuit is still tough to beat for distortion, balance, simplicity, and reliability.
as have about 130 volts to drop, do i even need a negative supply? i think i can just use the cacode inplace of the circuit i showed above. damn my lack of knowledge, spose everyone starts somewhere.
For the 5-20 circuit, you don't need a negative supply (one of the nice things about it). If it were me, I'd either use a cascode bipolar or (better yet) a DN2540 cascode. You could take the CCS right out of the ImPasse circuit, adjust it for the right current, and it will perform superbly.
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