I'm lookimg for 6v6 PP amp schematics that uses 6.6k OT

[Kagliostro]

I'm lookimg for 6v6 PP amp schematics that uses 6.6k OT primary impedances

Thanks

K

[JoeCon]

http://mhuss.com/Plexi6V6/Plexi6V6c.gif

It's a 6v6 plexi and uses a 6.6k OT, from the picture.

[Stevem]

Why? The impedance of the OT does not make a impact on circuit design other than power supply voltage by enlarge!

[Kagliostro]

I've a problem with a build that has a pair of 6v6 on a 6.6k primary OT

and I'm thinking they are due to a low B+ (450v CT AC PT with EZ81 rectifier), the original project used 6aq5 and a 6x4 rectifier

and I would like to see circuit that are like as to give a look to the B+

voltage used in those circuits

Thanks

K

[pdf64]

Th DR OT primary is around 6k6 http://bmamps.com/Schematics/fender/del ... _schem.pdf

[Stevem]

Well a ez81 / 6ca4 is only rated for a first cap of 50uf, are you running larger?

[Blackburn]

Deluxe Reverb or a TW Express are the first two that come to mind.

[Kagliostro]

Thanks pdf64 & Stevem

The first cap is 33uF

the schematic is this, but was build with V1 = ef86 - PI = 12ay7 - power tubes 6v6 - rectifier ez81

[img1043]http://www.bensykora.com/7cylinder/7cylinder_final.gif[/img]

there were some changes also in component values and the realized amp is this

[img1638]http://i.imgur.com/1WM0JHB.jpg[/img]

PT and OT are the same of the original schematic

K

[tubeswell]

fixed bias 6V6s work good with a 6k6 Pr Z when the plates are running around 400 or more. They even can sound good with fixed bias at 380 or 390.

[Littlewyan]

Trainwreck Express

[gui_tarzan]

Why? The impedance of the OT does not make a impact on circuit design other than power supply voltage by enlarge!

Wait, I thought the output tubes & OT had to be in the same impedance range for them to work correctly?

[Littlewyan]

They do but the impedance you use also depends on what voltage you're running the valves at. So a 6V6 running at 250V requires a 10K OT but when running at 285V the valves require an 8K OT. But this is only for perfect matching, as its a guitar amp rules don't apply . If the voltage is between 300V and 400V then 6.6K will work fine for 6V6s.

[pdf64]

I thought the output tubes & OT had to be in the same impedance range for them to work correctly?

The plate impedance of the power tubes we use seems to be 5 to 10 times greater than the primary load impedance.

The max power transfer theory http://en.wikipedia.org/wiki/Maximum_po ... er_theorem doesn't seem to apply, perhaps due to plate impedance not behaving as a simple linear resistance.

[gui_tarzan]

I still think there is magic working in these devices.

[Stevem]

Is that EZ81 gonna be pushed too hard with 350/350, I forget its limits, a 5y3 may be a better pick?