Tightening the low end on a Mezzabarba Trinity (SLO circuit)

[pipboy90]

I want to experiment with tightening up the low end and adding some high end cut to give more articulation. A Maxon OD808 in front of the amp sounds great, but I want to get the same result without the pedal (and without the extra mids and gain, as the amp already has enough of both).

Is it as simple as reducing the first or second .02uF coupling caps to .002uF? Trying out .68uF cathode bypass caps instead of 1uF?

Any tips/advice welcome.

 

[GlideOn]

All good suggestions, yes.

Reducing the PI entry cap is also a great way to cut some 'fat' out of it without neutering the gain.

I think you'll find that you may not have to add "high cut" once you tame the bass, so it's not excessively bright

 

[jasonP]

I want to experiment with tightening up the low end and adding some high end cut to give more articulation. A Maxon OD808 in front of the amp sounds great, but I want to get the same result without the pedal (and without the extra mids and gain, as the amp already has enough of both).

Is it as simple as reducing the first or second .02uF coupling caps to .002uF? Trying out .68uF cathode bypass caps instead of 1uF?

Any tips/advice welcome.

I built a slo clone and also owned a slo which is basically the same circuit as this amp and found the same as you. Do you want to change all the channels or just the od channel? The best way like you say is to reduce the first stage and possibly the second stage coupling caps from .022uf to anywhere from .001 to .0047uf. What ever you find best. .0022uf on the first stage is a good place to start. I liked .0022uf on first stage and then .0047uf on the second stage. I then go and put a .0022uf cap over the .0047uf cap on the depth pot in the feedback loop to get to .0068uf and up the feedback resistor to 47k or higher. I then take the PI filtering cap and up it from 40uf to 100uf. That is what I liked for high gain, more modern tighter aggressive tone for guitars that are tuned down.

 

[RedPlated]

If it’s the same as an Mzero, it takes quite a bit to get rid of the loose low end. It takes a combination of coupling cap values and dropping signal in multiple areas throughout the circuit to get a fast, immediate attack out of it. I also altered some of the cathode values and bypasses. I changed the filtering in the preamp too. It’s not a two or three component-change solution by any means with that amp.

If I remember right, the first coupling cap affects the clean, crunch and overdrive channels. So you may not want to alter the value there and focus elsewhere.

.68uF on a 1.8k cathode is probably not going to help. The .68 will shift the midrange cutoff and actually likely be counterproductive for what you want in this scenario. This is all subjective, maybe you will like it.

Compared to an SLO, I had to do more to the Mzero to get it equally as tight.

 

[Purgasound]

I don't like the cathode caps much larger than 0.68uF. The trade off is the coupling cap. If the cathode bypass cap is too large you need a smaller coupling cap to trim bass. If you go down to 0.68uF you may not need to drop the coupling cap all the way to 0.0022uF. You can try something closer to 0.01uF and it won't sound so thin. There are a bunch of high gain amps that even go all the way down to 0.001uF and that's ridiculous. Those high gain tones usually sound thin and anemic even when used with something like a 10uF cathode bypass cap. Whatever the case may be, it's not about what I think is cool. It's whatever you like to hear.

 

[JSutter]

Try a 470p coupling cap, or add one in series like most 5150's. You will loose a bit of gain.

As for "adding some high end cut to give more articulation", do you mean less fizz? A small cap 1n or so to ground before or after the tone stack is an easy way to cut the fizz.

 

[pipboy90]

Try a 470p coupling cap, or add one in series like most 5150's. You will loose a bit of gain.

As for "adding some high end cut to give more articulation", do you mean less fizz? A small cap 1n or so to ground before or after the tone stack is an easy way to cut the fizz.

Not less fizz, but more defined frequencies in the 2k-4k range that add a bit more cut.

I don’t know if I’ll end up modding the amp or not. Once it gets some volume it sounds great. And a boost pedal seems to be the easiest fix to get that added aggression when needed.

 

[SpiderWars]

For tightening up, sometimes increasing the cathode resistor a bit sounds better than reducing the cathode bypass cap or a combination of the two, within reason tho. It's probably going to be what it's going to be to a large degree so just tweek it a little at a time. It's easy to go too far.

 

[titanium777]

I want to experiment with tightening up the low end and adding some high end cut to give more articulation. A Maxon OD808 in front of the amp sounds great, but I want to get the same result without the pedal (and without the extra mids and gain, as the amp already has enough of both).

Is it as simple as reducing the first or second .02uF coupling caps to .002uF? Trying out .68uF cathode bypass caps instead of 1uF?

Any tips/advice welcome.

 

[titanium777]

Just add a eq in the loop this will allow you to dial in your desired tone to your liking

 

[glpg80]

For tightening up, sometimes increasing the cathode resistor a bit sounds better than reducing the cathode bypass cap or a combination of the two, within reason tho. It's probably going to be what it's going to be to a large degree so just tweek it a little at a time. It's easy to go too far.

Yeah get too aggressive with that and it starts to sound bad without changing other aspects to properly rebias the stage again. That suggestion leads down a deep dark path of tweaking hell if you aren’t 100% sure what you’re doing.

 

[Dan Gleesak]

I found a sonic stomp pro in the loop of a high gainer to be remarkable for tightening it up. Didn’t play my 8 string without it