Ideas for a Pedal Steel amp build

[LooseChange]

Looking for ideas.
I'd like to build one using a pair of 6550's to get some decent wattage. A simple preamp.
Steel players like loud, clean and full bandwidth.

[sluckey]

Look at the old Sunns. Perfect!

Plain Jane...   http://www.el34world.com/charts/Schematics/files/sunn/sunn_spectrum_ii.pdf

Reverb and trem... http://www.el34world.com/charts/Schematics/files/sunn/sunn_sceptre.pdf
Easier to see...      http://home.comcast.net/~seluckey/amps/sunn/sunn_sceptre_1971.pdf

Both are loud and clean.

[DummyLoad]

http://www.el34world.com/Forum/index.php?topic=11329.0

buttery cobbled together the preamp and tone stack, i cobbled the PI and had a hand in the output stage and PS. damn thing sounds really, really nice. the tone stack is tuned for bass guitar, but could easily be tweaked for pedal steel.

i would spec custom PT iron or see what could be built with off the shelf. right now he's using a PT i spec'd for another project that was a flop.
edcor could make a minor change to the bias winding (you wouldn't need the V tippler for the bias supply), without much trouble, however, i understand that edcor delivery is running up to 8 weeks now.

or just copy a twin... the quad of 6L6GCs can be replaced with a pair of 6550s with some tweaking. use the triode electronics dynaclone OT p/n A431S - highly recommended. hell for that matter...just build a dyna mark III clone and slap yer own pre-amp to it. use the triode electronics PT p/n P782S.

--DL

[DummyLoad]

Look at the old Sunns. Perfect!

Plain Jane...   http://www.el34world.com/charts/Schematics/files/sunn/sunn_spectrum_ii.pdf

Reverb and trem... http://www.el34world.com/charts/Schematics/files/sunn/sunn_sceptre.pdf
Easier to see...      http://home.comcast.net/~seluckey/amps/sunn/sunn_sceptre_1971.pdf

Both are loud and clean.

are we both attempting to send him down the same path? lol! 

--DL

[sluckey]

are we both attempting to send him down the same path? lol!

Absolutely! 

He specified... 6550, simple, loud, clean, full bandwidth. What else is there? Unless he wants a Peavey Nashville 400 which is also a fine steel amp, but no 6550s. 

[jojokeo]

Can someone explain point E going to the ultra linear screen taps? It appears to be a sort of NFB but I'm not familiar w/ this one?

[DummyLoad]

is also a fine steel amp, but no 6550s.

no 6550s! sacrilege! 

[DummyLoad]

Can someone explain point E going to the ultra linear screen taps? It appears to be a sort of NFB but I'm not familiar w/ this one?

it is NFB. it's summed with the NFP tap of the secondary... perhaps to aid in stabilizing ultrasonic oscillations?

[terminalgs]

from a circuit design point of view,  clean headroom is about a preamp that doesn't overdrive any of its stages, right?

[LooseChange]

Clean headroom is what it's all about.

I just learned that a Steel Guitar has a huge output form 20k pickups.
How do you design the input intto the first tube to handle that?
I am thinking about using 6SL7's as the preamp and phase inverter.

[jjasilli]

 note my post in this thread:

http://www.el34world.com/Forum/index.php?topic=10079.msg91915#msg91915

[Willabe]

Hey, what about using a 12_7 in parallel for the 1'st stage?

Not for extra gain, but shouldn't 2 grids be able to take more from the pedal steels pick up than just 1 grid? Just bias it cooler.


           Brad       

[LooseChange]

Okay... I want to keep it simple. Going to burn a pair of 6550's at around 500volts. I think building a Bassman aa864, just the normal channel will work great. I'll do some tweaking for input and tone controls for the Steel.
Do you think I'll get enough wattage with this plan?
What do you all think of this plan?

[jjasilli]

Looks like about 70 - 77 watts.  (UL is closer to 70.)  Seems plenty loud to me and a good plan. 

[jojokeo]

With such a large output from the 20k pu's it would seem worthwhile to put a volume pot/divider right on the input and maybe w/ a cap too.