You may laugh..but don't waste your time trying to dissuade me. 300B preamp.

[Bas Horneman]

phono preamp using a 6528

Suddenly a 300B preamplifier looks like a perfectly normal thing to do.

[jan.didden]

Originally posted by Bas Horneman
[snip]The thing I don't really understand about a current reg is this :
With what voltage do you need to supply it? AFAI understand it ...it does not really matter..since the filament will only be supplied with 1,2A? So I can supply 8V or 12V does not matter?
[snip]Bas

Hi Bas,

I don't know your particular current reg, but there will be a minimum voltage it needs to function - depending on implementation. And then there's the voltage across the load (heater). So, if the nominal heater voltage is 5V, and the current reg needs 6V to function, you need to supply it with at the minimum 11V. Obviously you should stay above that, but anything higher will lead to more dissipation in the current reg, that's just V x I, so you'd want to minimize that. (The V being the voltage between the two terminals of the current reg of course).

Jan Didden

[Bas Horneman]

Obviously you should stay above that, but anything higher will lead to more dissipation in the current reg

Thanks Jan,

That makes it crystal clear.. Thanks!

By the way it is a simple current reg on Doede's boards.
http://www.dddac.de/at05.htm

[Alkis]

Hi Bas,
Same thought came to me several months ago for a 300B line pre in order to drive my 845 monoblocks.The idea was to built a whole DHT system,from the beginning all way to the end.I wonder,what would be the sound of a projeckt like this after building preamplifiers with ECL-86,5687 and currently 6BX7.
300B is one of the most linear tubes has been ever made,it's a DHT,and as they say, the sound or the colouration of a stage is infected by the earlier stage.
An interesting approach is here,
http://www10.big.or.jp/~dh/work/93072.html ,which I thought to modify.
Anyway,I'm looking forward to seen the outcome of your search

[Bas Horneman]

Anyway,I'm looking forward to seen the outcome of your search

Thanks Alkis,

I will report my findings here.

Thanks for the link as well...wow..preamp with a 211!

Regards,
Bas

[845]

This is my 300B preamps (with STU-7003 Tamura 5k/150Ohm Line output transformers). The driver is C3m.

[845]

Inside

[Bas Horneman]

I knew there would be diy'er out there who had built a 300B preamp!

So you have opted for a gain stage before the 300B.. have you tried other topologies?

What do you think of your 300B preamp?

[845]

In my case the best result i had with C3m tubes (I used transformer input 845 power amps).I use local feedback in gane stage.



This is best preamp for my Power amps.

Iam very sorry for my Inglish

[Bas Horneman]

In my case the best result i had with C3m tubes (I used transformer input 845 power amps).I use local feedback in gane stage.

Nothing wrong with your english. ...I understand what you are saying perfectly