#26 pre amp

[rclourenco]

Originally Posted by merlin el mago

Just finished mine, tomorrow will be the great day to hear it, attached some pics just for fun. Finally and due to limited space inside the lineamp I used CCS+Gyrator courtesy of Ikoflexer also for same reason in place of Thomas Mayer TVCs I used a pot 100K log Noble, all RCA connectors are rodhium plated, all AC & DC connectors are Powercon & Speakcon, heaters regs are Rod Coleman used the chassis as heatsink, sockets are teflon Yamamoto, rectifier valve AZ1 and #26 are Cunningham waiting one globe Cunningham because one bought in ebay was spoilt it was not working the heaters. Waiting you will enjoy.

Very Nice Filipe,
I like the slim looks, and the aluminum mounts on the tubes bases!

What about the sound? Do you fill the tubes are microphonic?

Enjoy your build.
Cheers.

[amandarae]

Originally Posted by merlin el mago

Just finished mine, tomorrow will be the great day to hear it, attached some pics just for fun. Finally and due to limited space inside the lineamp I used CCS+Gyrator courtesy of Ikoflexer also for same reason in place of Thomas Mayer TVCs I used a pot 100K log Noble, all RCA connectors are rodhium plated, all AC & DC connectors are Powercon & Speakcon, heaters regs are Rod Coleman used the chassis as heatsink, sockets are teflon Yamamoto, rectifier valve AZ1 and #26 are Cunningham waiting one globe Cunningham because one bought in ebay was spoilt it was not working the heaters. Waiting you will enjoy.

Nice!

[merlin el mago]

Originally Posted by rclourenco

Very Nice Filipe,
I like the slim looks, and the aluminum mounts on the tubes bases!

What about the sound? Do you fill the tubes are microphonic?

Enjoy your build.
Cheers.

Originally Posted by amandarae

Nice!

Thank guys, before the hear the preamp I measured this morning feeding a sinus 1kHz and the result are not OK, attached pics, help will welcome.

TIA
Felipe

[vgeorge]

What is the second and third pictures?
Also, better stay below 1,5V on the heaters.

[merlin el mago]

1st pic is the sinusoidal measured directly by the scope. Second & third pictures are or better have to be 1Khz sinusoidal output left & right channel

[iko]

Please post the schematic with all measurements that you make (voltage, current) on the schematic.

[merlin el mago]

Schematic with measurements

[iko]

You have both a gyrator AND an output transformer? Ouch! I'd use either the gyrator with the output provided via a 4-6uF capacitor, or the output transformer. But not both. If you keep the output transformer then you need to make sure the supply voltage is appropriate so you get the 150V on the 26 plate.

[merlin el mago]

I need the OPT because power amps are SS.

[vgeorge]

Originally Posted by merlin el mago

1st pic is the sinusoidal measured directly by the scope. Second & third pictures are or better have to be 1Khz sinusoidal output left & right channel

Something is very wrong. Looks like serious oscillation. Be careful not to toast any tubes!
Listen to IKO.
I use the SSHV2 directly to the output transformer, and there is no problem.