freestompboxes.org

One question though: is this supposed to distort very early?

remove the clamping diodes on the output

I mean...I'm completely okay with it distorting where it does. Mostly curious whether I screwed something up. Good to know about removing those diodes in case I change my mind though.

hi, Bajaman,

thank you for this wonderful project!

what classification of the ksk117 would you recommend? GR or BL?
Idss: GR: 2.6~6.5 mA, BL: 6~14 mA

jeepe wrote: ↑09 Jan 2022, 22:42 hi, Bajaman,

thank you for this wonderful project!

what classification of the ksk117 would you recommend? GR or BL?
Idss: GR: 2.6~6.5 mA, BL: 6~14 mA

not bajaman but otherwise happy to help.

because of the 100k source resistor, the 2sk117 is running at such a low current that any classification is suitable.

the differences would matter in a much higher current application, closer to Idss.

mcrowe wrote: ↑19 May 2021, 23:12 I mean...I'm completely okay with it distorting where it does. Mostly curious whether I screwed something up. Good to know about removing those diodes in case I change my mind though.

I dropped the value of the gain pot to something tiny (I think 5 or 10k) and compensated by increasing the gain between pins 6&7 on the output opamp stage.

thank you, asbestosaurus!

I'm eyeing this up as something to give a try as I have a Behringer BDI currently that I'm reasonably pleased with but has a bit of noise with the treble all up and lack of control of the mids. Looking into the documentation I have been wondering how similar the ever increasing number of SVT in box style pedals out there are.

I see that this and the sansamp bass driver both make use of TL072 op-amps how similar are the circuits and sounds?

I noticed that the controls exactly match those available on the Master Effects Super 300, elsewhere on their website they mentioned using jfets in their other amp in box pre-amp pedals but don't specifically mention this in relationship to this pedal. I know RoG have a whole host of pre-amp modelling circuits using jfets so I was interested to know if anyone wondering how related it might be to those circuits.

Which has left me wondering how different other popular Ampeg SVT style pedals like the Broughton SV Pre and new Origin Bassrig and how much is pedal marketing bumph.

TL072s are a JFET based opamp, so they've got the box ticked. The mids control on this makes ll the difference between the and lots of other 'SVT style' preamps.

I love this pedal! Works like a charm, but to me the mida and 5 point switch are doing nothing…. Am I missing something? I triple-checked my build….

check again

bajaman wrote: ↑29 May 2022, 12:36check again

Touche.. will do, hehe! Thanks!

bajaman wrote: ↑29 May 2022, 12:36check again

Well, there's a reason why you're Bajaman and I'm just... whatever I am.

I quad-checked it, and I made a huge mistake. I feel so dumb, hahaha!! It works like a charm.

Having solved that issue, I have to say this is the most beautiful pedal I've even built. I will put it to very good use. Thanks a lot!

Please excuse my lack of knowledge on electricity but if I substitute the 3u3 in the Mid Freq control with a polarized Tantal, where would the + leg go?

tuck wrote: ↑27 Oct 2022, 11:37 Please excuse my lack of knowledge on electricity but if I substitute the 3u3 in the Mid Freq control with a polarized Tantal, where would the + leg go?

The easiest way if it is not immediately obvious from looking at the schematic is to fit a capacitor and measure the voltage across it with a multimeter.

I would use a normal electrolytic for this as tants don't like having reverse voltage on them. Once you find the correct orientation then swap it for your polarised tant.

Would I be ok to take a feed to an active (TL072) DI circuit at the point just before the last gain stage?
I’m thinking of taking a feed from in between the 2n2 and IC2b.

I would like to build this and add an output stage to drive my headphones. Any tips on how to do this? And any good available schematics on amplification that works for headphones, and doesn't ruin the beautiful Ampeg tone?

Good afternoon! Do you happen to have this project in PCB with printing? Thanks.

sorry - i do not have a pcb for this project
cheers
bajaman

Hi Bajaman,

this is now a bit embarrasing because I think I did everything right to wire a 3PDT as bright switch.
But I think I don't get the sonical function of it or I messed it up but I don't understand how.
Pin 8 & 9 are connected to an led.

If bright is on 2->3 and 5->6 then the sound is a tad lower in volume and slightly darker.
That should be the opposit, right?

And what would be the way to make the effect of the ultra high switch more prominient? I don't hear any difference with the 5nF capacitor.

Hello Tuck
The way you have wired the switch is correct BUT, it has been so long ago that i designed this pedal and upon investigation of the Ampeg SVT schematic the 220n capacitor is far too large to be effective - it should 4.7nF !
Also i would suggest changing the 330k for a 560k resistor, although the capacitor change will make the most noticeable difference
The Ultra High switch is mostly effective at low gain settings and becomes decreasingly effective at higher gain levels
cheers
bajaman
ps: check my latest post in the Bass Butler thread