Search found 196 matches

by Zokk
05 Aug 2022, 15:25
Forum: Amplifiers
Topic: Mesa Boogie Quad preamp / LDR drama
Replies: 10
Views: 2086

Re: Mesa Boogie Quad preamp / LDR drama

Hi, I've just finished to replace the vactrols and the electros capacitors... Accessing the pcb was not as difficult as I thought, just a bit of sport to work with the preamp in vertical position laying on its left side (like a book) to access both pcb sides at the same time to remove the solder pro...
by Zokk
14 Jul 2022, 19:58
Forum: Boutique Stompboxes dissected...
Topic: Demedash Effects - T120 Videotape Echo Pedal [traced]
Replies: 30
Views: 13553

Re: Demedash Effects - T120 Videotape Echo Pedal [traced]

There's also the option of a programmed µC, like the noise1 or 2 from Electricdruid https://electricdruid.net/product/noise-1b-noise-generator/ https://electricdruid.net/product/noise2-white-pink-generator/ If you can flash the PIC, there's the project page too (included code and tons of interesting...
by Zokk
10 Jul 2022, 12:51
Forum: Amplifiers
Topic: Mesa Boogie Quad preamp / LDR drama
Replies: 10
Views: 2086

Re: Mesa Boogie Quad preamp / LDR drama

Thank you! This is interesting! I'm tempted to "read between the lines": is it possible that they advised to change the resistors and optos because they changed their vactrol manufacturer and the "new" Vactec component has different specs? It seems the Silonix (Silonex?) parts ne...
by Zokk
09 Jul 2022, 14:12
Forum: Amplifiers
Topic: Mesa Boogie Quad preamp / LDR drama
Replies: 10
Views: 2086

Re: Mesa Boogie Quad preamp / LDR drama

It is so difficult to access to the tracks on the pcb that I would like to change all the critical components at once. The anode caps are really important and they live in tough conditions... they would probably fail before the other film caps I think. Also they are not so expensive compared to the ...
by Zokk
08 Jul 2022, 23:11
Forum: Amplifiers
Topic: Mesa Boogie Quad preamp / LDR drama
Replies: 10
Views: 2086

Re: Mesa Boogie Quad preamp / LDR drama

Hi Jose The VTLs are page 41: https://pdf1.alldatasheet.com/datasheet-pdf/view/84387/PERKINELMER/VTL5C1.html the datasheets for the GL55xx series are just "informative": https://datasheetspdf.com/pdf-file/756864/CdS/GL5537-1/1 According to the datasheet, R"on" is measured at 10Lu...
by Zokk
08 Jul 2022, 13:47
Forum: Vintage Stompbox Corner ( ... - 1975)
Topic: Systech - Harmonic Energizer [schematic]
Replies: 180
Views: 117552

Re: Systech - Harmonic Energizer [schematic]

Nice and clean! And space-saving compared to the originals.
This CNC work on the enclosures is great too!
by Zokk
08 Jul 2022, 13:14
Forum: Amplifiers
Topic: Mesa Boogie Quad preamp / LDR drama
Replies: 10
Views: 2086

Mesa Boogie Quad preamp / LDR drama

Hello my Quad Preamp has suffered from being stored during near a decade... yes it's a shame :roll: So of course I will have to change the electrolytics, all the orange drop capacitors which are on the anodes, and of course... the "vactrols"... Some of them have died at power-on, when I tr...
by Zokk
09 Sep 2021, 12:38
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Schalltechnik_04 - Pumpernickel [schematic]
Replies: 9
Views: 4899

Re: Schalltechnik_04 - Pumpernickel [schematic]

Hi great work! An idea would be to design an adapter to use the THAT4305 instead of the 4301. Like this one for example (no schematic ): https://www.sonelec-musique.com/electronique_realisations_clone-that4301-4305.html edit: full adapter documentation here https://github.com/chuckhousley/4305-adapt...
by Zokk
30 Jul 2021, 22:04
Forum: Boutique Stompboxes dissected...
Topic: Trip Hazard Optical Disruptor - Assymetric Optical Compressor/Low-Freq Saturator
Replies: 10
Views: 4397

Re: Trip Hazard Optical Disruptor - Assymetric Optical Compressor/Low-Freq Saturator

Hi you may be right, if the lower resistance on the LDR is not the goal there's no need to be able to supply 40mA from the opamp. That's a good trick to have a faster time response from the LDR and achieve FM-like modulations in a narrow range. In this case the LF351 should behave the same as a TL07...
by Zokk
25 Jun 2021, 22:37
Forum: Boutique Stompboxes dissected...
Topic: Trip Hazard Optical Disruptor - Assymetric Optical Compressor/Low-Freq Saturator
Replies: 10
Views: 4397

Re: Trip Hazard Optical Disruptor - Assymetric Optical Compressor/Low-Freq Saturator

Hello I'm always amazed to see a TL084 driving a VTL5C1... this opamp is ok for audio, but not really as LED driver :scratch: It should not be able to provide enough current to the VTL LED, so I don't think the min/max chart posted earlier means something in this case. Remember those VTLs need 40mA ...
by Zokk
22 Jun 2021, 12:35
Forum: DIY Projects
Topic: Dux Hazer 8 stages optical phase shifter
Replies: 3
Views: 1421

Re: Dux Hazer 8 stages optical phase shifter

Yes there are several ways to change the rate of the LFO2, sources are LFO1, EF (positive or negative), and expression pedal/external CV.
You're right this was thought to be able to route all the modulations like on a modular synth (it has also CV in and CV out 0-5V).
by Zokk
22 Jun 2021, 11:37
Forum: DIY Projects
Topic: Dux Hazer 8 stages optical phase shifter
Replies: 3
Views: 1421

Re: Dux Hazer 8 stages optical phase shifter

I read again my message and I said a wrong thing: The "invert phase stuff" works in " single " mode... I had to dive again in my schematic to remember some details :? Too complicated yeah... so in "single" mode ("dual" footswitch not engaged) both LFOs + envel...
by Zokk
21 Jun 2021, 16:05
Forum: DIY Projects
Topic: Dux Hazer 8 stages optical phase shifter
Replies: 3
Views: 1421

Dux Hazer 8 stages optical phase shifter

The story of this project began when a friend of mine asked me to modify his phaser (a classic 4-stage FET that I can't remember the part number of) so that he could disengage the LFO and use it as a fixed bandpass filter. The simple operation made him so happy that he asked me to build him another ...
by Zokk
19 May 2020, 21:15
Forum: Pimp-My-Cheap-Pedal
Topic: can I build an effects pedal with side jacks and top jacks
Replies: 6
Views: 2040

Re: can I build an effects pedal with side jacks and top jacks

I've often wondered why nobody offers this sort of layout as it would be super versatile? I'm about to build my very first pedal (a Tube screamer type clone from a kit) but I'd certainly like to have input/output jacks at the side AND the top...how would I wire them in parallel? Nobody offers this ...
by Zokk
26 Jan 2020, 21:52
Forum: Amplifiers
Topic: Sunn Beta Bass preamp schematic
Replies: 112
Views: 89464

Re: Sunn Beta Bass preamp schematic

Hello I've built a Beta Lead aswell, I used the "common" schematic. It sounds awesome! But the Level pot is quite scratchy at the beginning of the sweep, like if it passes DC signal (kind of a SHO behaviour). I don't understand the output stage of this preamp: usually the potentiometer is ...
by Zokk
20 Jan 2020, 10:44
Forum: Vintage Stompbox Corner ( ... - 1975)
Topic: Marlboro - Quadra Sound Blender QBS [schematic]
Replies: 35
Views: 34415

Re: Marlboro - Quadra Sound Blender QBS [schematic]

Hello the general rule with old electronics is to change first all the electrolytics capacitors, so you can have a steady power supply and make measures of the rest of the circuit clearly. Those "tropical fishes" capacitors are prone to cracking, if you want to avoid further problems I'd s...
by Zokk
17 Jan 2020, 16:54
Forum: Pedal Debugging & Troubleshooting Support
Topic: Big pedal board project 20 odd effects inside
Replies: 6
Views: 1430

Re: Big pedal board project 20 odd effects inside

Modman is right, I also love your build, it's very impressive outside 8) However you should take really care of the psu, a bad choice and it will ruin the whole build with ground loops, noise, etc. As I said many cheap psus are sold as "isolated", but their are not galvanically isolated. T...
by Zokk
15 Jan 2020, 20:45
Forum: Pedal Debugging & Troubleshooting Support
Topic: Big pedal board project 20 odd effects inside
Replies: 6
Views: 1430

Re: Big project help needed.

Hello Are you sure the HB power supply is really isolated? I've opened other cheap power supplies and very few are effectively isolated; I mean all the regulators are fed by only one secondary from the transformer. You can check it easily: unplug the power supply and all your pedals insert some DC j...
by Zokk
24 Sep 2019, 07:13
Forum: Software Room
Topic: LushProjects online simulator [link]
Replies: 0
Views: 20368

LushProjects online simulator [link]

Hi
I've recentely discovered this very nice simulator, very good for small circuits and learning.
http://lushprojects.com/circuitjs/circuitjs.html

JFETs and OTAs are in the "Misc. Devices" list 8)
by Zokk
23 Sep 2019, 08:29
Forum: Pedal Debugging & Troubleshooting Support
Topic: audio probing a steel string stinger from pedalpcb
Replies: 11
Views: 2034

Re: audio probing a steel string stinger from pedalpcb

Hi it does not seem normal to me to see +9.21VDC on the gate of Q2. will need the help of a more skilled person to explain that. If you have a PF5102, it is more like a J111, a chopper/fast switch. Not sure how it will behave in this circuit. You may try with 2SK117, 2N5457... N-Channel small signal...