sushi box grand slampegg

[havnjero]

looking for some clarification to mod a new pedal, grand slampegg, made by sushi box, and figured I'd use this forum instead of talkbass for the details.

it sounds real nice, and its nearly what I need in order to have a single pedal for double bass performance, so that I don't have to bring a pedal board or drive to a gig.

I'm good with an iron, but not sure exactly what components to change. here are my ideas:

1.
it isn't running a 5691 -- could be because it doesn't support the heater current needed.
6SL7 needs 0.3a and a 5691 needs 0.6a
should I change the 78M06 to a 1amp 6V voltage regulator for getting more power to the heater?

2.
changing the high pass filter from 6db/oct@90hz to a brick wall at 53hz.
space available is at red marking, courtesy of @Tassieviking. thanks!
looks like theres not a lot of space available, but what components do I need to have in there?
I know this is complicated.

3.
input impedance.
I though that 5.6MΩ would work but I need at least 10MΩ. 15.6MΩ may be ok, so I'll try adding a 10M to see how that works. it'll be switchable in the end.

@vigilante398

 

[benny_profane]

@vigilante398

 

[jwin615]

A multipole filter isn't going to be a couple of components. You need an active circuit and even that won't be a "brick wall" in the analog domain without a LOT of components. The phase shift you start introducing forces you to get into higher parts counts if you want more than 12db/octave.
The smallest TH multipole I know of is this guy
Not sure if you can hack that into your pedal easily though.
You can alter the values to change the corner frequency as desired.

 

[vigilante398]

1) not sure if you'll be able to find a higher output 6V regulator in the same package, but if you use an L7806 (1.5A output) you can mount it to the wall of the enclosure (you'll have to find an empty spot of course) and jump wires down to the pads from the 78M06.

2) as mentioned above, a steeper sloped HPF is only doable in active filter land, which means it will be a lot more complicated than just swapping a component or two. Again it may be possible to jump out a separate circuit board with some wires, but again you'll run into real estate problems as Grand Slampegg is pretty packed.

3) if you want to add the resistances you'll have to add them in series, not parallel, which means the 5M6 resistor is going to have to get removed either way.

 

[matmonster58]

I upped the hpf cap on my nobelium build for upright and its now set at around 50hz. It's pretty perfect for my upright to leave on all the time. I don't think think a steeper filter slope is al that necessary tbh. Steep analog filters do weird stuff to the phase response and create a resonance in more extreme cases.

I have a vampire slayer with 5.5meg or 11meg impedance. I was shocked to find the 5.5meg sounds way more natural with my k&k pickup. The tribal knowledge on talkbass had me thinking higher was always better. 10meg sounds fine in my nobelium, but i haven't tried different values. My MXR m81 has a 3.3meg impedance and I've never felt it was lacking. It's a different circuit and you probably have a different pickup but a higher input impedance isn't always better from my experience. I just got a new bass with a realist pickup, i haven't had a chance to try it with my different pedals yet

 

[havnjero]

I upped the hpf cap on my nobelium build for upright and its now set at around 50hz. It's pretty perfect for my upright to leave on all the time. I don't think think a steeper filter slope is al that necessary tbh. Steep analog filters do weird stuff to the phase response and create a resonance in more extreme cases.

I have a vampire slayer with 5.5meg or 11meg impedance. I was shocked to find the 5.5meg sounds way more natural with my k&k pickup. The tribal knowledge on talkbass had me thinking higher was always better. 10meg sounds fine in my nobelium, but i haven't tried different values. My MXR m81 has a 3.3meg impedance and I've never felt it was lacking. It's a different circuit and you probably have a different pickup but a higher input impedance isn't always better from my experience. I just got a new bass with a realist pickup, i haven't had a chance to try it with my different pedals yet

what is the value for the hpf cap you used?

I still would like a hard cut around 53hz. the corner needs to be as steep as possible.
perhaps I should experiment further with this on the steddi or finally v2.

 

[vigilante398]

what is the value for the hpf cap you used?

I still would like a hard cut around 53hz. the corner needs to be as steep as possible.
perhaps I should experiment further with this on the steddi or finally v2.

Adjusting the cap isn't going to change the corner, the passive RC filter is only going to give you -6dB/octave no matter what you choose. If you need a steeper slope you're going to need an active filter.

 

[Tassieviking]

What if you have more then one HPF in the circuit ?
Will they then steepen the curve ?
The XLR pot and the Volume pot in parallel gives us a resistance of 167415.43 ohms, with C7 being 100nF it would give us a HPF of 9.5Hz
With C7 being 22nF we would have a HPF of 43Hz
With C7 being 33nF we would have a HPF of 28.8Hz
With C7 being 20nF we would have a HPF of 47.5 Hz (two 10nF in parallel)

Or am I working this out wrong here ? Maybe the changing value of the pots screws up my little brain wave here.

 

[LukeFRC]

It would be so so much easier to build and run a fdeck HPF into the slampeg - get the buffer at 10M, the HPF, phase….
Dual lock them together if it has to be one thing!

 

[vigilante398]

It would be so so much easier to build and run a fdeck HPF into the slampeg - get the buffer at 10M, the HPF, phase….
Dual lock them together if it has to be one thing!

The Fdeck is one of the designs I used for inspiration for the variable HPF I put in my Finally v3, it's a great design. I'm not sure I could fit it into Grand Slampegg without going to a bigger box though.

 

[LukeFRC]

The Fdeck is one of the designs I used for inspiration for the variable HPF I put in my Finally v3, it's a great design. I'm not sure I could fit it into Grand Slampegg without going to a bigger box though.

I know it’s kinda against the ethos of diy scene, but if I were the OP I would just have two boxes rather than try and mangle a new sushibox! I’ve had enough mods go wrong to know sometimes it’s not worth it