BAJA Ampeg SVT bass amplifier pedal 9v 010418 [documentation]
- bajaman
- Old Solderhand
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One question though: is this supposed to distort very early?
remove the clamping diodes on the output
remove the clamping diodes on the output
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- jeepe
- Breadboard Brother
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- Joined: 10 Jun 2019, 16:48
- Completed builds: I might be at level 2, so to speak..
not totally green, but that's all :)
my "level" is about building a big muff... medium complexity :)
I'll never build a DS-2, for example :)
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even though I'm a layman to electronics
I'll never build anything without seeing the actual schematics too...
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my all time favorite: Fuzz FAce
it is an always ongoing project..
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I want to end up strumming some strings at the end of the day, whatever the sound
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I'm so sad that this beautiful culture (and freedom movement) is totally ephemeral - Location: Budaspest, Europe
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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
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
pedal building, tracing and sharing is such a beautiful freedom movement... If only it could be viewed as a future heritage, but it really is ephemeral, as it seems
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.
- Paul_5
- Breadboard Brother
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.
The sounds in my head don't match the sounds from my amp, I guess that's why I'm here...
- jeepe
- Breadboard Brother
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- Posts: 73
- Joined: 10 Jun 2019, 16:48
- Completed builds: I might be at level 2, so to speak..
not totally green, but that's all :)
my "level" is about building a big muff... medium complexity :)
I'll never build a DS-2, for example :)
- -
even though I'm a layman to electronics
I'll never build anything without seeing the actual schematics too...
- -
my all time favorite: Fuzz FAce
it is an always ongoing project..
- -
I want to end up strumming some strings at the end of the day, whatever the sound
- -
I'm so sad that this beautiful culture (and freedom movement) is totally ephemeral - Location: Budaspest, Europe
- Has thanked: 625 times
- Been thanked: 22 times
thank you, asbestosaurus!
pedal building, tracing and sharing is such a beautiful freedom movement... If only it could be viewed as a future heritage, but it really is ephemeral, as it seems
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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.
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.
- Paul_5
- Breadboard Brother
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.
The sounds in my head don't match the sounds from my amp, I guess that's why I'm here...
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….
Pedro Cucaracha
(Easy, cheap and dirty)
(Easy, cheap and dirty)
- bajaman
- Old Solderhand
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check again
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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!
Pedro Cucaracha
(Easy, cheap and dirty)
(Easy, cheap and dirty)
- deltafred
- Opamp Operator
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.
Politics is the art of so plucking the goose as to obtain the most feathers with the least squawking. - R.G. 2011
Jeez, she's an ugly bastard, she makes my socks hurt. I hope it's no ones missus here. - Ice-9 2012
Jeez, she's an ugly bastard, she makes my socks hurt. I hope it's no ones missus here. - Ice-9 2012
- Paul_5
- Breadboard Brother
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’m thinking of taking a feed from in between the 2n2 and IC2b.
The sounds in my head don't match the sounds from my amp, I guess that's why I'm here...
Good afternoon! Do you happen to have this project in PCB with printing? Thanks.
- bajaman
- Old Solderhand
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sorry - i do not have a pcb for this project
cheers
bajaman
cheers
bajaman
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- tuck
- Breadboard Brother
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.
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.
- bajaman
- Old Solderhand
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- Joined: 26 Jun 2007, 21:18
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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
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
be kind to all animals - especially human beings