No glow for me with the OD3

[bainjs]

I emailed Eileen about a replacement.  I still don't understand how the FP3 could be working with the OD3 not operating.  Very strange stuff!

Thanks

Joel

[JC]

From reading this exchange, it seems as if the suspect is the regulator tube.  If it is indeed bad, the rest of the circuit is still getting the unregulated power supply, so it works but not at its best.  The regulator tube is supposed to be shunting some excess Voltage (and, current, though that is not really the main issue) to ground, and thereby establishing one fixed operating point for the amplifier circuits that stays fixed regardless of the signal.

To put it way too simply, tube amplifier circuits tend to operate with three operating parameters that are constantly changing with the applied signal; if you pin one of those three down and make it constant, as with using a shunt-regulated supply, you generally make the tube amplifier more linear, or accurate, if you will.

[bainjs]

Thanks for putting it "way too simply".  That makes sense even to me. 

So, even though it sounds good, it may sound better when I get a replacement tube.

I hope that's the issue!

[bainjs]

After checking and re-checking the connections going to the OD3, out of frustration and thinking I had nothing to lose, I thumped the tube and it lit up!  That's probably not the best thing to do to a tube but so far, it still working. 

Thanks for everyone's help and suggestions.

Joel

[JC]

OK, so while it is on, do you think you can get those Voltage measurements again?

Meanwhile, do you hear a difference?

[Grainger49]

My brother and I call this "The Scientific Method."  Also used by Andy Griffith used it to good stead (on a tube type radio) in No Time For Sargents. 

[bainjs]

I have to admit, I come from a long line of thumpers.  I'm sure my granddaddy practiced it with his Atwater Kent and his Zenith "Cobrahead" console record player.  I wonder how many will know what I'm talking about...

Still glowing.  Using the Creek remote, it seems to be easier to adjust the volume at low levels. In the past, the volume would be too low and slightly turning it up, it would get too loud.  I guess they call that more linear.

Joel  

[bainjs]

The FP3 seems to be running a lot cooler now even with the OD3 working.  I have mine in a open backed cabinet and previously, I would keep the glass door open a little for more ventilation.  Now even with the door closed it's much cooler running. 

[Grainger49]

IIRC, Doc has a background in restoring old radios.

[Doc B.]

Radios, PA stuff, microphones, old test gear, you name it. Last radio I did was my 1956 Telefunken Salzburg Console, including a Telefunken tape deck. We listen to our favorite blues show on it every Saturday and Sunday night. Current resto project is a fairly rare Hammond Model E concert organ with D-20 and DR-20 power cabinets.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fwww.hammond-organ.com%2FMuseum%2Fimage_directory%2FmodelE.jpg&hash=f7b5638793f0fe1c275581f22698e145215d15e2)

[bainjs]

Then you might be familar with the Zenith Cobrahead tonearm 78rpm record players. It was in a large cabinet that the turntable pulled out and when you played a 78, the tonearm head would wiggle back and forth.  Those snake eyes would freak me out as a 4 year old. 

The fact I remember it 50 years later attests to impression it put on me. Scarrry!

[JC]

An E?  Good for you!

I roadied one of these around that had been built into an Anvil case way back when; KILLER blues organ!

[Doc B.]

The thing is really crazy inside. Tremulants run off of the drive shafts at the end of the tone generators - the chorus is a whole second set of detuned tone generators. Completely different than any other Hammond, separate expression pedals for swell and great manuals, pedal piston presets, typewriter keys for manual presets. I grew up listening to Jimmy Smith so of course I am already working on fitting in a percussion preamp from an L-100 in a manner that looks factory, and trying to scrounge up a Leslie 31H.

[JC]

Yes, the Leslie would really complete the package!  I sure hope you can post some audio clips as you go...

[Doc B.]

Yes, when I get the thing running I hope to get Art Khu to come up and tape him playing it.