Dynaco Mk3 Poseidon input/driver boards

[stereohifi]

Hi, knowing that pcb's are no longer available, i will do a point to point poseidon circuit based on that design.

Planning on using LM334 for constant current source the 12AX7 input tube.

I saw that 12AU7 driver could be subt. for a 12BH7A, any mods I have to look for this driver stage?

Since Poseidon designer does not sell or follow??? theses boards or circuit, is there recent mods I have to take to before start installing and soldering parts???

Thanks

 

[Demonkleaner]

DIYTube Mark III Poseidon Driver Board

 

[rayma]

Using a CCS on the input will alter the stability of the circuit, and increase noise.
The 12BH7A is much better as a driver than the 12AU7.

 

[stereohifi]

[URL="https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=2ahUKEwjsl-y166vnAhUYXc0KHbVNDbYQFjAAegQIAhAB&url=http%3A%2F%2Fsite.triodestore.com%2Fposeidon.pdf&usg=AOvVaw2ICAvdlCNm8iVJcuFAGMlR”]MKIII h - Triode Electronics[/URL]

Yes I know about this previous link , thanks but they don't have the pcb anymore.
I'm looking for some user feedback regarding 12BH7A driver.
It is pin-to-pins drop in tube, but operation is the same???

I've use this 12BH7A in the vg Quicksilver's V4 monobloc.

Thanks.

 

[stereohifi]

Using a CCS on the input will alter the stability of the circuit, and increase noise.

Then a low value resistor ?Which type metal film?

 

[rayma]

Then a low value resistor ?Which type metal film?

Are you talking about the 12AX7 plate resistor?

 

[rayma]

I'm looking for some user feedback regarding 12BH7A driver.
It is pin-to-pins drop in tube, but operation is the same???

Pinout is the same, but electrically they are not the same.
However the circuit is adjusted to work with the 12AU7, so use that.

 

[stereohifi]

No, the driver stage 12AU7 pins 3 and 8 where U1 LM334 is current source.

 

[stereohifi]

Found this food for though:
diytube.com • View topic - 12AT7 Inverter in Poseidon Mark IIIs

 

[rayma]

No, the driver stage 12AU7 pins 3 and 8 where U1 LM334 is current source.

That will be ok.

 

[snapper]

I cloned the Poseidon board, the 12AX7 half can now be selected in my version with solder jumper.
If they are interested just let me know!

 

[petertub]

Hi, knowing that pcb's are no longer available, i will do a point to point poseidon circuit based on that design.


Planning on using LM334 for constant current source the 12AX7 input tube.


I saw that 12AU7 driver could be subt. for a 12BH7A, any mods I have to look for this driver stage?


Since Poseidon designer does not sell or follow??? theses boards or circuit, is there recent mods I have to take to before start installing and soldering parts???


Thanks

This is an oxymoron. A Dynaco MkIII has no poseidon bords. An amp with poseidon bords is a 60w amp made
with some dynaco parts.

An accurate title could attract knowledgeable people, an suspect title could repulse readers.

 

[nerdorama]

I think it is accurate. It says Poseidon board

 

[dgranger]

Snapper, I am very interested in your Poseidon clone boards. Please let me know if they are available and how I can obtain a pair.

 

[baudouin0]

A 12BH7 will work just fine in place of the 12AU7 the DC plate voltage is not determined by the choice of valve (as long as the grid does not go positive) but by the CCS and the 68K. Gain is not much different. Heater current is double however.