Ample Alpaca - less low end and less gain mod?

J

john kurzweg

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Ive just finished an Ample Alpaca , compared it to and old ggg red llama and an ehx hotwax and it seems to have more gain than both of those---still pretty dirty with the gain knob all the way down.
It also has more sub lows than my llama....
Im wondering if there are any component mods etc that can tame the gain and the low end just a bit...?
And...... should i have used a reverse pot for the tone control? -- it's working backward from expected...
Any help/suggestions are much appreciated!

I should mention this is my first successful build that's not from a kit .... i gave up on it a year ago when i was building 3 non-kit pedals and none of them worked when i "finished" them...(!) -- I decided to pick the A.A. up again in the last few days (the alpaca was the simplest) and some troubleshooting paid off.....yay! (I'm a complete noobe, so I have to give myself some cheerleading..... )
 
"Im wondering if there are any component mods etc that can tame the gain and the low end just a bit...?"
Ample Alpaca parts numbers will be referenced
R2 could be lower. In the original llama it is 100K and in the ample it is 91K. you'll have to consider this your minimum gain resistor so lowering it sets the minimum gain lower
R4 could be lower. In the original llama it is 1M. you may not notice much difference making this change as 1M is already enough to have plenty of op amp clipping
that said, the ample alpaca has a hi-cut tone control and series resistor R6 that are not a part of the original llama and I surmise they upped the gain so they lose less signal to a passive tone control. it may be negligible amounts of loss so trust your ears

to change the tonality, you would be changing things that are shared between the ample alpaca and the red llama, namely the coupling caps. I'd start with taming the gain to your liking first as it might solve both problems
 
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john kurzweg said:
Ive just finished an Ample Alpaca , compared it to and old ggg red llama and an ehx hotwax and it seems to have more gain than both of those---still pretty dirty with the gain knob all the way down.
It also has more sub lows than my llama....
Im wondering if there are any component mods etc that can tame the gain and the low end just a bit...?
And...... should i have used a reverse pot for the tone control? -- it's working backward from expected...
Any help/suggestions are much appreciated!

I should mention this is my first successful build that's not from a kit .... i gave up on it a year ago when i was building 3 non-kit pedals and none of them worked when i "finished" them...(!) -- I decided to pick the A.A. up again in the last few days (the alpaca was the simplest) and some troubleshooting paid off.....yay! (I'm a complete noobe, so I have to give myself some cheerleading..... )
Click to expand...
You’re not done with them if they don’t work. Other than that, I’m no help.
 
ICTRock said:
"Im wondering if there are any component mods etc that can tame the gain and the low end just a bit...?"
Ample Alpaca parts numbers will be referenced
R2 could be lower. In the original llama it is 91K. you'll have to consider this your minimum gain resistor so lowering it sets the minimum gain lower
R4 could be lower. In the original llama it is 1M. you may not notice much difference making this change.
that said, the ample alpaca has a hi-cut tone control and series resistor R6 that are not a part of the original llama and I surmise they upped the gain so they lose less signal to a passive tone control. it may be negligible amounts of loss so trust your ears

to change the tonality, you would be changing things that are shared between the ample alpaca and the red llama, namely the coupling caps. I'd start with taming the gain to your liking first as it might solve both problems
Click to expand...
thanks ICTRocks! --- I'll try the r2 and r4 swap when i can-- maybe I'll socket those so i can try different values.....So here's a complete nuub question - Is there a way on a schematic or pcb to tell which caps are for coupling?
jimilee said:
You’re not done with them if they don’t work. Other than that, I’m no help.
Click to expand...
I probably wasn't clear that the Ample Alpaca is working, i just thought it had a little too much low and gain -- the other 2 projects (or 3!) ill return to at some point -- they were a little more complex and i may have to start over...
 
john kurzweg said:
thanks ICTRocks! --- I'll try the r2 and r4 swap when i can-- maybe I'll socket those so i can try different values.....So here's a complete nuub question - Is there a way on a schematic or pcb to tell which caps are for coupling?

I probably wasn't clear that the Ample Alpaca is working, i just thought it had a little too much low and gain -- the other 2 projects (or 3!) ill return to at some point -- they were a little more complex and i may have to start over...
Click to expand...
I'm going to assume you don't want the large textbook explanation of coupling caps so I'll cut to the chase with part numbers, again referencing the ample alpaca part numbers.
C1, C3, C5

easiest "explain it like I'm five" I have is that they couple circuit blocks together. larger values let more low frequencies through, smaller don't.

C1 couples the input to the first amplifier, C3 couples the two amplifiers, C5 couples the second amplifier to the output in the original llama. C5 being 10u is your biggest opportunity for attenuating excessive bass and could be replaced with anything from 100n to 10n and more or less hit all the sweet spots for guitar. I'd probably stay within the 68n - 33n range since that's what's being used ahead of it in the circuit.
 
ICTRock said:
I'm going to assume you don't want the large textbook explanation of coupling caps so I'll cut to the chase with part numbers, again referencing the ample alpaca part numbers.
C1, C3, C5

easiest "explain it like I'm five" I have is that they couple circuit blocks together. larger values let more low frequencies through, smaller don't.

C1 couples the input to the first amplifier, C3 couples the two amplifiers, C5 couples the second amplifier to the output in the original llama. C5 being 10u is your biggest opportunity for attenuating excessive bass and could be replaced with anything from 100n to 10n and more or less hit all the sweet spots for guitar. I'd probably stay within the 68n - 33n range since that's what's being used ahead of it in the circuit.
Click to expand...
thank you , really appreciate it !
 
The GGG version has a difference from other versions - note the difference in where R2 (in GGG schematic) is placed vs the equivalent R3 (in PedalPCB schematic). This clearly leads to gain differences between the two PCBs.

For the GGG schematic, w/ the Drive pot minimized, the feedback loop for U2 has 100kohm in series w/ 51pF at low frequencies and ~100kohm at high frequencies.

For the PedalPCB, w/ the Drive pot minimized, the feedback loop for the equivalent IC1.6 has 100kohm || 51pF at low frequencies and 51pF at high frequencies.

1753835794743.png
This is the GGG schematic

1753835912598.png
This is the PedalPCB schematic (consistent with others I've seen, e.g., Beavis Audio, etc.)
 
that spurred me to go back and correct my initial statement about that series resistor as well. there's also the tube sound fuzz to consider ... I believe the 1K resistor (ample alpaca R100) lowered to 100R is a pretty good difference maker as well.
 
Hmm, and I'll also add to my earlier comments.

Also note the differences in the feedback loop for the 2nd IC stage in the schematics posted in $9 above - specifically R3 = 1Mohm for GGG, vs the equivalent R4 = 2Mohm for PedalPCB. So there are multiple sources of gain differences.
 
I think these are the differences between the 2 knob red llama (GGG)and the three knob 25th anniversary model.

Bernard d'Uur came up with this tone mod: (Forget about the R5)
 

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john kurzweg said:
And...... should i have used a reverse pot for the tone control? -- it's working backward from expected...
Any help/suggestions are much appreciated!
Click to expand...
I just thought I'd chime in about this since I thought the same thing! But you'll notice on the schematics it's called "hi cut" and not "tone" as is typical on gain pedals. When you are at full ccw this lets the whole frequency spectrum through, and turning it clockwise rolls off the high end and its quite a lot at full cw. Im sure you noticed at the higher cut settings the drive get pretty dark!
 
@Robert FYI confirmed OP's suspicions that the tone control (Hi-cut) on this project is backwards from original. This is probably not news but I'm too lazy to look before wasting your time with an @
 
ICTRock said:
@Robert FYI confirmed OP's suspicions that the tone control (Hi-cut) on this project is backwards from original. This is probably not news but I'm too lazy to look before wasting your time with an @
Click to expand...

Ahh, no, I wasn't aware of that.

The "Hi Cut" label is probably how it has managed to go unnoticed.
 
Thanks to ALL for the great suggestions --- VERY helpful --- I didn't know till today there were so many responses--- ALL appreciated!! ( I haven't been receiving the email notifications for some reason --- need to tweak my forum or email settings--- ).
And.... In my possibly not so humble opinion , the GGG version is a great sounding and versatile pedal .... especially for 2 knobs.....
 
Lowering the value of C6 could be of benefit. As mentioned, that's a pretty aggressive filter.
Even at barely on(1k) corner frequency is ~4k and at max it's 48Hz!
A lower value pot could also be used.
A 25k pot at max would be 193Hz
A 10k would be 482Hz
 
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