Highway 89 build, and questions

[Barcode80]

so i put the Highway 89 together from MarkM's pcb layout. I must say, that is some balls to the wall OD there! it sounds great, but I did notice the treble and bass controls did very little, the treble i can't really hear any change to the frequencies and the bass only slightly more difference. Is this common, did any of you experience this? is it possibly to do with the pots (i used 500k for both and just used 120k resistor across the outside lugs to bring resistance down to about 98k) or is this just a characteristic of the circuit? i love it as is anyway, so it is getting boxed, but if the controls are supposed to be this subtle, i'm just going to jumper those pads for the tone controls and box it in a 1590B with only level and gain controls, but if they are supposed to be more responsive, i have some debug ahead of me.

[oldrocker]

Yes the tone control is subtle.  You should get a little something from both treble and bass but not a whole lot.  Yes no matter how I set this it sounds great.  Looks like you got it working congtrats on making a really nice pedal.

[Barcode80]

jumpers it is then!

[Barcode80]

is this the way i would bypass the pots?

[John Lyons]

The way the tone controls work is very literal. The treble control only rolls of the high end and the bass is only true bass.
I kind of like how this works because even with the controls set off the sound is usable. Listen to the hiss or amp noise while turning the treble control. It's similar to the cut control on VOX and matchless amps.
Using the bass knob will make a larger difference with a load amp. It's more of a rumble cut...

John

[Barcode80]

i'm sure the controls are useable for others, but on my little 30 watt SS amp i gig with, i like the sound better with both those knobs cranked. so i figure i will remove those controls and "preset" them to max. is the above image how i would go about that?

EDIT: so, i tried what i show in the above image, and though i'm not sure how it is different from having a cranked pot in there, it is behaving strangely. i am now getting great signal just like before, but in addition i am also getting a VERY loud low freq oscillation unless i turn the gain all the way down (which i'm assuming only makes it go away because this kills the signal completely). the pitch varies slightly when i roll the guitar volume back and forth. any ideas?

[Barcode80]

BUMP!

i just subbed in 100k trimpots for the externals in case i want to make tweaks later, but i sould still like to know how to go about replacing the pot in a circuit with a fixed value, as a lot of my pedals get set once and left there for eternity. i know anything that shunts to ground can be replaced with a fixed resistor from the pad for lug 3 to the pad for lug 2 (assuming lug 1 is ground) that equals the resistance across lugs 2 and 3 at the setting you want. but in cases like the highway 89, i can't quite make out how to replace the pots with fixed values.

[John Lyons]

The fixed resistor should go from lug two to lug one putting 100K resistance from the .047 cap.
This would be the same at the treble pot turned all the way up and 100K resistance from the .047 cap.
So lug 3 trace jumpered to lug two and a 100K resistor from lug 2 to lug one.

The bass connections are done the same way. (jump 3  to 2 and 100K from 2 to 1. )

John

[MartyMart]

I made mine with a single BMP TC that was slightly modified and it works well.
Centered, its a good full tone without too much high end, turned up it starts to
thin out and get more highs, lowered cuts highs and gets a more "mid hump/bass" thing
going on - but no where near as fat as a big muff control, it's more subtle and useable.
MM.

[Barcode80]

if i were to implement the BMP tone control, how would i go about that? would i eliminate the the pots to a fixed resistance and then tack the bmp on to the output?