Hammond AO-29 project

[1blueheron]

Some thoughts for you.   DaGeezer and I both thought the FAT triode was sort of a "set and forget" thing.  It did add a little something but later I used the FAT triode as a cathode follower after the 5879 pentode.  The CF after the 5879 helped smooth out the OD tone, IMO.  * see attached schematic

The other thing was the 5654 paralleled with the 5879 was kind of an interesting feature.  I used them paralleled, just the 5654 and just the 5879.  After some time playing all those options, I thought the 5879 alone sounded the best.

The TOS is really not a clean to OD amp.   It's more of a pushed mild OD tone to a strongly pushed OD tone.

DaGeezer and I viewed it as a tweakers amp.  Something you built with the original design and then changed components and topology until it evolved to what you personally preferred. 

With respect, Tubenit

Tubenit, thanks for the thoughts, corrections, and recommendations.  As of right now, all of the amps my son and I have built are pretty clean unless pushed by pedal.   We don't have anything that really fits in  the "high gain" category so building this as a bit of a tweaker should keep him occupied and happy as that is the zone he likes to live in right now.   

[tubenit]

For clarity ………….    I am NOT saying you "should" change anything from your original schematic.  Just offering some thoughts and considerations that may or may not be useful to you.

 

Keep us posted.  I'll be following this with interest.       With respect, Tubenit

[1blueheron]

For clarity ………….    I am NOT saying you "should" change anything from your original schematic.  Just offering some thoughts and considerations that may or may not be useful to you.

 

Keep us posted.  I'll be following this with interest.       With respect, Tubenit

   Just digging into your schematic and I like what you changed.  I think it will be cleaner layout and a little easier to build as you have drawn it.   Many thanks for taking the time to help out on this and graciously letting me tinker with several of your brainchildren at once.   

I still need to get a full understanding of all the pots and what they do and figure out placement on the chassis and decide if I will use a board, or do it all PTP.    I also need to finish my 18 watt before I get to deep into this but I am excited I have a winter project!

[bmccowan]

Sorry it looks like I misled you.

Thanks for following up. I'm likely a ways away from doing anything with that AO-14 as I have a few projects in front of it. I do have some 30W resistors though that should be useful to get the voltage down. Or maybe the thing is to run something else off it while playing - like a space heater.

[High Voltage]

Thanks a bunch High Voltage. Like the voltage doc sheet.  That is very useful.  If its not too much trouble, would you mind sharing what your power supply section consists of?  Did you use a choke or not and what dropping resistor values did you arrive at?

I remember with this one I had to do a spreadsheet to work out the dropping resistors as I have 5 stages and it was a balancing act between dropping the late stage voltages and keeping the early stages high enough. My setup ended up:

20uF - 1K - 20uF - 4.1K - 20uF - 8.7K - 10uF - 2K - 10uF

I put a 20/20/10/10 cap can (+ and extra 20uf in front) from CE where that existing cap can in the middle of the chassis was and it turned out to be a nice cleanish way to distribute the B+. The chassis lends itself well to doing point to point.

Also, be mindful of the voltages as soon as you turn on the B+ before the tubes start conducting. On this amp they were touching 450VDC which was my cap rating. I think if I was going to re-do this amp I would do the first two nodes with series caps to double their voltage rating.