trinityamps.com

I built a Lightening from scratch a while ago. Been tweaking the thing since. I thought the gain scheduling throughout the amp was a bit front heavy. I've got better overall control now and I think the amp sounds really good. Here is what I've done....
* Backed off the gain on the parallel input tube. 100k plate, 1.5k/.47 uf cathode.
* opened up the decoupling cap (was 1200p) now .022
* omitted the cathode bypass cap on the follower.
* changed the tone control to a Fender style with the midrange set at 8.2k
* dumped the 220k to ground going into the PI
* moved that .01uf in the PI that goes to ground to the junction of the 1m, 1.2k and the 47k/ (This was a mod Hoffman did on his stout amp, I believe by mistake but works well)
* swapped the 22k/22uf coupling to the screens on the power tubes to 10k and no cap.

Sorry, if you think this is way out there. I've been tweaking for years and tone is my bone.

Thanks for the tweaking info.

There are plenty of people who want to tweak their amps. The lightning is a great amp, but I have had people who wanted to clean theirs up as well.

What would you say, made the most difference? If you were going to do one or two things to clean up, what would they be?

I'd like to take your tweaks and starts a Lightning tweakers table. If you dont mind, I'd like to get your twaeks on the list.

Cheers,

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

You can use all my ideas... I share!
I think the number one change is reducing the gain by removing the Cathode Bypass caps in the preamp.
The tone control change with a dip in mids definitely helps.
AND my favorite...
* dumped the 220k to ground going into the PI (tone killer)
AND to compensate for the jump in volume...
* moved that .01uf in the PI that goes to ground to the junction of the 1m, 1.2k and the 47k (This was a mod Hoffman did on his stout amp, I believe by mistake but works well)

I can elaborate just ask.

I'll [eventually] turn these tweaks into a revised schematic and give the parts numbers based on the schematic I have posted in this forum.

viewtopic.php?t=500

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Thanks for the tips.
I'm a little confused on your component designation.
You mention a 220K to ground going into the PI. Do you mean the 220K that connects to the treble pot or the 100k that goes to ground that connects to the 220k?

Also confused about the 22k/22uf you mention going to the screens on the power tubes. Do you mean the 220k's and .022uf's?

I also thought the Lightning was a bit front heavy for my tastes so I ended up disconnecting the second parallel stage of V1.

I'm going to try removing the follower bypass cap. I might even put it on a toggle switch if there's enough of a difference with it in and out.

KevinL,

Take a look at loosechanges site. Maybe it's clearer then.

http://loosechange.freeservers.com/photo4.html

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

I don't have my amp in front of me right now but...

I don't see that 220k to ground on the Trinity layout or the schematic. There's only the 220k that comes off of the wiper on the treble pot. That one appears to still be there in his layout.

The 220k is actually a 100k, even more gain dumping. On the Trinity schematic it is R11... Sorry bout that!

Got it....thanks. I'll give it shot.

Be sure to move the .01uf in the PI - C8 to it's new position.

Ok, I removed the 100k and moved the .01 and removed the cathode bypass cap on the follower. I didn't do the screen resistors and caps or the tone stack mods.
I thought it made the amp a little too anemic for me. It's starting to get away from what the Lightning is. I put the 100k back and the .01 back to ground but put the cathode cap on a toggle switch so I can toggle between gain modes. I like the way it handles the gain change but doesn't affect the tone much at all.

I'll occasionally put a 12AY7 in V1 if I want it any cleaner.

Leave it all where it is and just try the Tone stack change. You might like that. My point was to make the amp a bit more linear and not blow the power tubes immediately into distortion. Just turn it up a bit more.

So Kevin, right now, you are just switching in the cathode cap and changing tubes for a cleaner sound? And this was an improvment.

Try a 2.7K cathode resistor for the clean sound and maybe move the 1.5K to the switch with the cap?

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

My goal with the Lightning was to get it to sound a little more like a 15 watt AC30 on the edge while having the Lightning's volume in the first half or more of it's range. I don't mess with the Master, I just keep it all the way up. I'm thinking of bypassing it anyway.
The Lightning has a lot more gain than I thought it would. Removing the parallel stage in V1 has helped and so has the removing the bypass cap in V2. The problem seems to be that doing too much more really makes the amp sound wimpy with no punch or attack.


LooseChange, I think you're right about not sending the EL84's into full on distortion so early. I know that's part of what gives it it's sound but if I could get a little more overall volume, attack, and punch with less power tube distortion, I might be there.

So you are saying if I left everything as the original schematic and just changed the tone stack, it would not drive the power section so early? What about the bias? Has anyone tried messing with that? How does changing the screen resistors and removing the coupling caps affect the power tube distortion?

OK, I've got it where I like it now. These are the changes that I've made from the original and it's sounding really good to me now.

The 2 biggest changes I found to getting the Lightning to go from clean to mean and have full usable range of the volume knob were to change the cathode bias bypass cap to 22uf instead of 220uf. That and removing the second/parallel stage on V1.

Putting the cathode bypass cap of V2 on a switch to remove it gives even more gain options.

I also put two .001uf caps in series where C1 is and it really tamed the bass which was boomy to me. It sounds much tighter now and the tone controls have much more usable range.

I really want to make this a 30 watter now. Coco, do you have drawings to do that? What about the 30 watt tranny set?

Serving up a 30W right here - viewtopic.php?t=45

Transformers are available I think. Email me of you want the OEMs.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

So to remove second/parallel stage on V1, you removed the jumpers from 1-6, 2-7 and 3-8 on V1 - correct? You just had to make sure the connections to the cthode and V2 remained in place.

_________________
Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

The easy way would be just to disconnect the jumper betweet 2 and 7 and ground the half you don't want. Heck, you could put a switch on it and have a choice on the fly!

You know, I did forget to disconnect 2 and 7. I wonder if that has a negative affect on the tube having a signal on the grid with no cathode or plate voltage. I'll disconnect it anyway.

Yeah, you could switch it but I found that switching the follower cathode cap in and out gives a nice gain change and it's easier to do.

I'm going to look into doing the 30 watt modification.

I really like the parallel tube. I use the low input and a 5751.