Tube Pre Amplifier for SEWA 7 Watt ClassA MOSFET

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
6C45 preamp

Ryssen said:

I´ve heard that to,the dull thing,and I thought about a CCS at the tail to Yeah, you may bee right about that to..If I decide to go that way with a CCS loaded 6C45 will 15-20mA be enough?thats what I have to play with.
And I would be happy if someone could explain what the 15,5v at the gates on SEWA does.:)


Ryssen at 15-20 mA you should expect perfomace similar to your pentode 6c45 design you have now. There are a wide choice of CCS in the Solid State world, Gary Pimm and Bas Horneman both have done a lot with these as well as Doc Bottlehead. I have posted my variation earlier. Gary Pimms self bias CCS is nice. http://www.pacifier.com/~gpimm/self_bias.htm
 
hello
Ryssen ( lineup lives near to you, I think )

www.tubecad.com

If you scroll down you have articles like:
http://www.tubecad.com/articles_2003/Grounded_Cathode_Amplifier/index.html

Grounded-Cathode Amplifier
The grounded-cathode amplifier is approaching its centennial (2007) and it remains the building block of most tube audio equipment. It is simplicity itself, with little more than a few resistors and a triode; yet many are ignorant of its inner workings.
19 Jan 2003 PDF


I dont know what article meant:
May I suggest you read the Tubecad article on the technique and come back better informed.



I wouldnt just throw out an advice to read
and forget to give exact link to project, for example:
DoZ Headphone Amp - A New Use For The Class-A Power Amp

Rod Elliott (ESP)
Updated 03 Oct 2005

.. actually I wouldnt think basic version has enough gain for SEWA preamp
But the HEADPHONE version of DOZ PreAmp should have
enough OUTPUT CURRENT to drive most any power amplifier input


linep :cool: audio advisor
Lineup Audio Labor Party
 
lineup said:
DoZ Headphone Amp - A New Use For The Class-A Power Amp

Rod Elliott (ESP)
Updated 03 Oct 2005

.. actually I wouldnt think basic version has enough gain for SEWA preamp
But the HEADPHONE version of DOZ PreAmp should have
enough OUTPUT CURRENT to drive most any power amplifier input


linep :cool: audio advisor
Lineup Audio Labor Party

actually looking at the schematic,
the VOLTAGE GAIN of DOZ HEadPHONE AMP is
(R9+R4) / R4
2920/220= 13.27272727

Maybe we would need something like ~20.0

No problem for me to change resistor and get good gain for SEWA
actually this is OFF TOPIC,
and should be in SEWA original TOPIC in Pass Laboratories
... but as I started this TUBES topic Myself ( halojoy )
I take me some unique rights here ;) :D

An externally hosted image should be here but it was not working when we last tested it.


The Output transistors are Motorola MJL4281, N-Channel !!!
The MJL4281A and MJL4302A are PowerBase power transistors
for high power audio.
• 350 V Collector−Emitter Sustaining Voltage
• Gain Complementary:
Gain Linearity from 100 mA to 5 A
High Gain − 80 to 240
hFE = 50 (min) @ IC = 8 A
• Low Harmonic Distortion
• High Safe Operation Area − 1.0 A/100 V @ 1 Second
• High fT
http://www.datasheetarchive.com/datasheet.php?article=2397671

>> http://lineup.awardspace.com/ <<<
 
This is my preamp i am use and i hope it will drive my sewa.
 

Attachments

  • 417[1].jpg
    417[1].jpg
    45 KB · Views: 676
I have been bussy with this SEWA hybrid thing
An externally hosted image should be here but it was not working when we last tested it.

It´s a 6c45 CCS stage:
An externally hosted image should be here but it was not working when we last tested it.

It seems to be working fine through my junkspeakers,the only problem now is that i found out (Thanks Fuling)the supply for the tubes are a bit weak.I can use 15ma/tube but if I go higher I only get hum,will order a bigger trafo wich I use backwards on the SEWA supply,and try it out on my better speakers.
An externally hosted image should be here but it was not working when we last tested it.

cheers.;)
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.