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#26 pre amp

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Gyrator like Iko used? It seems to complicated for me, could you please post a schematic how can be used with VR150?
 

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Then I suggest OPT, choke or gyrator. Resistor voltage drop will skate you our of the loadline.


In my mind, 150v is far too low a B+, because it doesn't allow you to use a proper load on the 26. Even if you want to use an active load such as a CCS or a gyrator, these work best with 70-100V headroom. If you want to operate at ~150V on the tube, I suggest having 220V B+ at least.

I would suggest increasing the B+ and using a VR150 and VR75 in series to get 225V, followed by a CCS set to 6-7mA. Alternatively you could also use a resistor or go back to your transformer load.
 
Using an anode resistor is a very poor idea. I would forget it. Various solid state anode loads are interesting - I tried these at some point and preferred the OPT, but haven't revisited this lately. I would simply use the transformer and forget about output caps. Try it as it is first.

My experiences with the 26 is that it has good sound at several different operating points. I have run it at 90v and 3mA and it sounds surpringly good at that operating point. You are not going to have poor sound within the range 90-180v

Filepe - you have now practically built your 26 preamp. I think this is the time to stop agonising over possible choices and just listen to it. You will need a reference listening test for any future modifications anyway. Experiment later and then see if it sounds better or worse or the same as it is with the OPT and VR150. This is exactly what I'm listening to as I write, and it's a perfectly good sound. Have a good Easter and enjoy your build. Play some music!

Andy
 
Filepe - you have now practically built your 26 preamp. I think this is the time to stop agonising over possible choices and just listen to it. You will need a reference listening test for any future modifications anyway. Experiment later and then see if it sounds better or worse or the same as it is with the OPT and VR150. This is exactly what I'm listening to as I write, and it's a perfectly good sound. Have a good Easter and enjoy your build. Play some music!

Andy

Andy wise example;)
care
DIY is highly addictive:confused:
must take breaks:D
 
Member
Joined 2009
Paid Member
Using an anode resistor is a very poor idea. I would forget it. Various solid state anode loads are interesting - I tried these at some point and preferred the OPT, but haven't revisited this lately. I would simply use the transformer and forget about output caps. Try it as it is first.

My experiences with the 26 is that it has good sound at several different operating points. I have run it at 90v and 3mA and it sounds surpringly good at that operating point. You are not going to have poor sound within the range 90-180v

Filepe - you have now practically built your 26 preamp. I think this is the time to stop agonising over possible choices and just listen to it. You will need a reference listening test for any future modifications anyway. Experiment later and then see if it sounds better or worse or the same as it is with the OPT and VR150. This is exactly what I'm listening to as I write, and it's a perfectly good sound. Have a good Easter and enjoy your build. Play some music!

Andy

Thanks for kind advice Andy, I will folow your advice, I wish you happy Easter.

Felipe