old thread

[utervo]

Thanks.

I decided to go with 6N1P for the preamp tube, has anyone got any experience with?

[Andy Le Blanc]

Amen..... I had a pile of junk, a cheesey ohm meter, and a soldering iron.....the first chassis I beat out of an old heat sheild from the back of a wood stove...... I've used mixing bowls and scrounged street signs..... dont let yourself be convinced that you have to get this or that just because....

[utervo]

Well, I've got all the stuff now, the speaker is being delivered this week. I went with Eminence Cannabis Rex after all.

Has anyone used the 6N1P? Anything else I need to take account except the heater wiring? I wanted to try it as they go for a lot less than the 12AX7, new SED Svetlanas cost half of what their 12AX7 does.

[utervo]

I am a bit confused about the heater wiring, for 6N1P I just connect the heater wires to pins 4 and 5 and that way I get the right voltage for it? With the 6AQ5A I connect the heater wires to 3 & 4 and I'll get the right voltage there, and create the artificial center tap from pin 2? My metal films a 2w and they are frigging huge for the 7-pin miniature socket, can use half watters for it?

For the 125ESE wiring I'd like to know if I can connect the NFB-line straight to the 10k / 4ohm as I am not planning use an output jack for it, I am a bit confused if it's alright that the NFB is picked up from there while using for example the 5k / 8ohm for output?

[utervo]

Wiring is almost finished, but I am a bit puzzled how the OT transformer is wired, secondary I think I know, the black is the ground and the colored ones I'll put to jack tips and one of them to 22k resistor for NFB, but the primary I want to check with you speacialists.

So where does the brown and blue go? In the ceriatone layout the other goes from pin3 to OT and the other from first filter cap and 10k resistor intersection to the OT. The Angela says the blue goes to pin4 and the brown to pin3, in the Ceriatone layout there goes a wire from 2nd filter cap and the two resistors to pin4, so which way im supposed to do it?

Thank guys.

[Andy Le Blanc]

plate leads are blue
B+ leads are red
but not always... did you settle on a hammond tranny?
if so then the B+ is brown
double check the hammond site for the secondary

[Andy Le Blanc]

looks like you might be getting mixed up between layouts and color codes
the ceriatone layout looks to be for a 6V6
and your using a 6AQ5?..... double check
the tube data and base diagrams

[utervo]

I've checked the pins for 6AQ5A and put them in the right ones (i think), the plate for 6AQ5A is pin5, so i'll put the blue to plate and brown to intersection between the first filter cap and the resistor.

What I'm confused still is that in the ceriatone layout there goes a wire from the 2nd filter cap straight to the screen and in the Angela layout it says I should connect the other OT wire to screen...

[Andy Le Blanc]

both layouts are correct...
the angela page has a thumbnail towards the bottom
of a 5F2
the schematic will show the screen grid as you think it looks
and it is one way to hook up the output
the ceritone showes the other way
the screen grid with its own tap on the power supply
this gives you an option
they will sound a little differnt
there are some reliability issues with the 5F2 hookup
if you want to crank the amp.... alot.... it might eat tubes
the ceritone is a bit more modern and may be more of
what you expect

[utervo]

Hooked it up the Ceriatone-way.

I've been measuring the caps, one interesting thing is that on the other 0.022uF cap I can't get a resistance reading, on the other one it rises when I'm measuring, I assume that is the cap loading up. When I measure them I can get a reading on both but it seems the one I can't get a reasistance measurements charges up less voltage. Is it the tolerances of the caps or have a blown the other one by heating it too much while soldering, they got pretty hot unfortunately?

Haven't fired it up yet, trying to figure out how to put two sockets in series to connect a lamp. It trust in patience, noticed I had one of the output jacks connected wrong (fixed after i took the pic)... Here are a few picks, any death traps visible?

[Andy Le Blanc]

looks good ...but always double check
the hard part is going between the 2D image of a schematic...
to the 3D image of the real thing
get a copy of the schematic and go through the amp from the power supply
to the input ...visually and physicaly verify the connections

If the cap is no good it will leak D.C. you'll get a significant volts reading on side not hooked to the plate....

it looks like you can put a light to on side of your power switch...
a neon hooked the switch... or a 6.3 light and houseing
the power tranny is right there..... whats your filement volts?
Ive a couple projects were I ran 12V fil. and wired 6V light and tube in series
that works....

[Structo]

Just a bit of advice, tidy up your lead dress.
If you get oscillations you won't know were to start unless things are tidy and short.

[utervo]

Yeah the wiring is a mess, a bit hard to plan the first time around, but I think I'll try it on before I start redoing it.

[utervo]

Tried it with a light bulb in series and nothing happened, what wattage the lamp should have for such a small amp? Tried 60w and 40w and some 11w, but I think it was some energy lamp or something. Could it be that the amp can't draw enough to ligth the bulb?

I had the rectifier tube on and tried a few others. Measured the first filter cap after switching off and it measured something like 1V.

[utervo]

Forgot to plug the amp in!

Seems to work with all tubes in, haven't measured the voltages yet.

The amp seems to make a very slight hum (the sound of electricity) on it's own, haven't plugged it in as I don't have a cabin... Worrysome hum?