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In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET
Post Subject: Some explanationsPosted by Romy the Cat on: 7/27/2020
I see, let me to explain how the this work all together the you will be able to make your own judgement. Let look at the functional purpose of the emails in there.
The R1 resistor is a loading resistor. This is understandable. It makes sense to keep it high as we have 5 parallel channels to run that drops the impedance to 1/5.
The R2 is the resistor over which the positive bias is suppled, balancing the input to 0V. It is a good idea to keep is as high as possible as it acts as a decouple between the tube and the adjustable resistor. This DC voltage goes directly were the signal flows what so it should “conditioned” as much as possible. The higher R2 resistor the less the AC signal “sees” the elements behind the resistor. BTW, you have in there missing another resistor and a very small capacitor to the ground over which noises get shunted. This cap very impactful to sound, so you could experiment with it.
The R3 and R4 is are a regular voltage divider set to align the output of your mid-bass channel with the rest of the channel. It your room it might need a different adjustment depending on how you room response to the given position of your mid-bass horns.
C1 is a low pass filter again the impedance of everything you have on the right.
R7 is the same as R2 but for negative supply. There are a lot of missing there as well but you might did it internally to make the drawing dimplier. Do experiment with that C2, that cap, in particularly on negative supply for some reasons VERY MUCH affect sound. I ended up use an electrolytic cap, which is kind of ridicules but sounded the best to me at that time.
R6 is a grid resistor. It is very fast tube with a tendency to rind and to have microphonics, so the grid resistor helps little bit with that. You can put sone ferrite into play that would do the same. When you just turn the amp and it is stone cold you can clearly hear a very unpleasant sound with a lot of ringing. That is from 6E5P grid. BTW, the length of that ugly “glossy” sound high be a good is a good indication for you when to change the 6E5P.Rerurn to Romy the Cat's Site