Different fets he has, different Rload values lead to different combined values, has lowMC cart etc.
No, buffer fets they will only heat up more which is not good. If with resistor load we needed more. This one will run at Idss. The output coupling cap value is a matter of the driven impedance not to create any high pass into audio frequencies, and not being too big in a phono so not to pass the eccentricity of records a lot if the amp goes low strong and the speakers are not loaded under Fs like in reflex.
P.S. Your Rload, R3, C4, Cout see to be your best components. For C2, C3 there are 1% MKP1837 cheaply accessible in your continent.
P.S. Your Rload, R3, C4, Cout see to be your best components. For C2, C3 there are 1% MKP1837 cheaply accessible in your continent.
Oi Ricardo, tudo bem?!
I'm just experimenting with transistor outputstage with transformer output... for short info it outperforms my tube phono stage - Salas I see you smiling
Source folower with 600 ohms output and a DMOSFet, alternative an Emitter follower with a low power BJT.
@ Salas:
what about a dual transistor, like a LS210, in the 1st stage instead of 2 SK170? I'm thinking of better stability.
Do you have a datasheet link? Merlin has single die LSK doubles and DL103R, it does great. But with the small degeneration resistors, singles track together OK too. The gain has to do with Id, Vpinch and rload mostly than matching gm.
What exactly are you experimenting with? Loosely based on mine but with LCR and trafo coupling? ''Tubeing'' it to the max?
What exactly are you experimenting with? Loosely based on mine but with LCR and trafo coupling? ''Tubeing'' it to the max?
P.S. That buffer did not oscillate on any of my preamps yet, and I avoided a series output damping resistor, but it may require 100R if you get trouble, while the classic is more resilient. Resistors in series damp dynamics somehow the bigger the value, DCB1 experience showed.
Salas,
I attached the LS 310 datasheet as PDF-file.
I'm experimenting the output stage with outputtransformer in the source / emitter to ground instead of the output cap. Transformer with 1:1 ratio and 600 ohm impedance.
I'm just experimenting and listening, so I'm not sure what I like more... like to know your comments on the advantages / disadvantages!
Regarding loop controls, is it better then to use a differential stage for the BJT?
I experimented in the output stage with a BJT and a DMOS for the output buffer but I prefer the sound of the SK170 and the DMOS and not mixing them.
Boa noite Ricardo
I would replace the RC circuit completely by adding an source follower with a 600 ohm load - you can use an 600 ohm resistor which is the output impedance and as well the load for the LCR RIAA. Because of the high input impedance of the SK170 in the 2nd stage the LCR circuit will work properly.
João