Amentum Boost/EQD Arrows for Bass Mods

irvmuller

Active member
I'm loving the simplicity of the Amentum Boost and would love to try it on bass. However, looking at reviews of the EQD Arrows from talkbass, the biggest issue, for those of us who play at the lower end of the scale, is that it loses a lot of bottom end. I'm considering getting the Amentum and figuring out how to make it a little more bass friendly though.

First, I'm considering changing out C2 with a higher value to let more bottom end through. Maybe I'll stick in a 100n.

I'm also considering changing the 2n5089 out of Q1 with a 2n2222a. It's less gainy but has more bass and is smoother.

The concern is how does the rest of the circuit get affected by those changes.

If you have other suggestions or thoughts please share. Thanks.

Attached is the schematic.
 

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It’s such a small circuit, try socketing the Q and cap to see how much that affects the sounds. You can always permanently solder it w/o the socket once you dial it in.
 
It’s such a small circuit, try socketing the Q and cap to see how much that affects the sounds. You can always permanently solder it w/o the socket once you dial it in.

Yeah, I was planning to socket Q and start with the 2n2222a. I'll try whatever else I have with me. It is a tiny circuit so I don't how much that limits my ability to experiment.

You think changing C2 would make a difference as well? I'm very new to this and am definitely still learning.
 
I'd go way bigger. Say a 1uf at c2 and 470n ish at c3. You might need to go to a 2.2uf at the input cap down the line but see how you go.

thanks for your suggestions! I will try them out and post back on here to let everyone know how it goes.
 
thanks for your suggestions! I will try them out and post back on here to let everyone know how it goes.

How did this work out for you? I love the Arrows, but I want to make a switchable "more bass" mod if possible. What was your eventual transistor and cap combo?
 
How did this work out for you? I love the Arrows, but I want to make a switchable "more bass" mod if possible. What was your eventual transistor and cap combo?
More than possible!

It's such a simple circuit, you don't even need to breadboard it...

Build the circuit stock, then add some caps in parallel to the input/output caps via alligator clips — or breadboard it, it's such a simple circuit that it makes a great intro to breadboarding if you've never tried.

Once you've found which cap-values work for you, solder those caps to an on-on toggle switch to bring them in parallel with the stock values and you've got a guitar/bass friendly build. (DPDT, one pole per in/out cap respectively)

Yet another approach would be to add in a pot instead of switch. Solder in the larger value for the output cap, then for the input cap you'd add a large cap in parallel to the stock input via a pot. Joe Gore shows how to do this input-cap mod for a Bazz Fuss:

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You could also experiment with a small cap in parallel to R3 to bleed off some treble; I've no idea what value, but 500p could be a good start and adjust the value up/down to taste, as low as 100p to as high as 1n possibly.



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