glpg80
Well-known member
Here’s a video of that Laney boosted with an SD-1
glpg80
Well-known member
Yours will be more aggressive than that, to be honest. The GH100S takes that 4th stage and feeds it into a cathode follower which mellows it out.
Yours will be closer to an Aldrich
Yours will be closer to an Aldrich
ledvedder
Well-known member
Which side of the 50/50 cap should I pull B+ from? One side is 392v, the other is 373v.
glpg80
Well-known member
Is one side the phase inverter phases?
You’d want to pull from whatever side doesn’t also have the phase inverter voltages pulled.
As has been said before, you’re aiming for ideally around 160V+ at the pin for best tone. Ideally 175V+ IMO.
ledvedder
Well-known member
373v is going off to v1. The 392v side was going to v2 previously.
glpg80
Well-known member
Pull from the 392V for V2
ledvedder
Well-known member
I'm getting 172v on pin 2 and 125v on pin 6.
FourT6and2
Well-known member
What are you getting on V1a now? That should ideally be at least 160v. Not the end of the world if it isn't, but that will keep things tight and woody and not fizzy and loose.
ledvedder
Well-known member
These are my pin 1 and pin 6 plate voltages.
V1A - 208
V1B - 211
V2A - 172
V2B - 125
PI - 222
PI - 216
V1A - 208
V1B - 211
V2A - 172
V2B - 125
PI - 222
PI - 216
glpg80
Well-known member
The 220k is doing what it should, all looks good to me.
(392-125)/220k is 1.21mA, 1.21mA * 1.5k is 1.82V, so the stage is working correctly.
How does it sound? In the right direction you’re looking for?
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ledvedder
Well-known member
I still have to connect the caps, so it doesn't sound like anything yet
glpg80
Well-known member
The anticipation 
FourT6and2
Well-known member
You can also lower the value of those plate resistors on the additional stage if there's too much gain/fizz or if the amp feels too loose.
glpg80
Well-known member
Yes agreed. To OP: You can always put another 220k in parallel and see which you prefer.
I find it tames a lot of the ice pick bite of a completely stock circuit since it’s much much later in the game without having to go to snubbers. 220k will also increase the gain.
ledvedder
Well-known member
No time this weekendThe anticipation
glpg80
Well-known member
So cloooseNo time this weekend
ledvedder
Well-known member
Well, I found a few hours today to finish things up. I got to play it and fiddle with the controls for about 20 mins. Here's my impression...
It sounds killer for that heavier style all the time, which isn't really my thing. I'm definitely more of a dynamics guy, which it seemed to lose. Not much gain change with the preamp pot. It's more just adding more highs as I dial it back. Obviously the bright cap doing what it does. The tone controls are definitely more active. Dialing back the guitar volume doesn't really clean it up, it basically gets muddy. I clipped a 1M pot across the 1M resistor and played with different values. It didn't seem to do much except add more woofy bass. And there's obviously much more hiss overall.
Don't get me wrong, it's a killer tone, if that's your thing and what you want out of it, but I think I prefer the previous setup. I don't know, I'll give it a few more days before I decide if I want to change it back to a standard 2204.
It sounds killer for that heavier style all the time, which isn't really my thing. I'm definitely more of a dynamics guy, which it seemed to lose. Not much gain change with the preamp pot. It's more just adding more highs as I dial it back. Obviously the bright cap doing what it does. The tone controls are definitely more active. Dialing back the guitar volume doesn't really clean it up, it basically gets muddy. I clipped a 1M pot across the 1M resistor and played with different values. It didn't seem to do much except add more woofy bass. And there's obviously much more hiss overall.
Don't get me wrong, it's a killer tone, if that's your thing and what you want out of it, but I think I prefer the previous setup. I don't know, I'll give it a few more days before I decide if I want to change it back to a standard 2204.
glpg80
Well-known member
Regarding the mud, try changing the first coupling cap to 0.0022uF
You may have to clip the bright cap on the gain pot to decrease the gain and highs both as you roll down the gain knob - otherwise it will do what you say and make the highs more prominent.
Your feedback is important and will help us help you - Here are some other things to try regarding the added stage.
After you fix the first coupling cap, Add another 220k across the top 220k plate resistor. This will help add back in some dynamics.
Try Clipping a 470k in parallel with the 1M voltage divider. It will tighten the bass rolling the volume down.
You can change the cathode resistor from 1.5k to 2.7k to add back in some harmonics/dynamics. Keep it unbypassed for now. If it’s in the right direction, you can go higher to 4.7k. If the gain drops off that you liked before, you can start bypassing it.
If after all of these changes (any combination of them as well) and it’s still not what you’re looking for, then rip it out and go back to a cathode follower 3 stage design with a stock 0.02uF coupling cap.
Let me know if this gets you in the right direction.
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ledvedder
Well-known member
A few things I've tried already.
Adding another 220k in parallel with the 220k plate resistor didn't seem to make much difference that I could tell.
A 0.0022 first coupling cap definitely brought back some snarl.
I tried a 10k in the 3rd stage cathode, similar to this layout I found. It dropped some gain a bit, but still not very dynamic.
Adding another 220k in parallel with the 220k plate resistor didn't seem to make much difference that I could tell.
A 0.0022 first coupling cap definitely brought back some snarl.
I tried a 10k in the 3rd stage cathode, similar to this layout I found. It dropped some gain a bit, but still not very dynamic.
glpg80
Well-known member
Have you tried the 2.7k and 4.7k of the 4th stage?