This was a request and offers something quite different.... it is a tape syle diode compressor. Notice that it runs on 16v biploar power so if you want to power it with normal 9v, a bipolar volatge doubler daughterboard can be used.
*Edit* 270421. Now verified and I got some reports it works perfectly fine using a simple FET Booster up front.
Schematic and info is avaiable HERE.
Excellent!
ReplyDeleteThank you!
Oh nice. I've looked at these before, they sound great. I wonder how you would incorporate the drive control from the main unit that these modules plug into?
ReplyDeleteNot sure to add the drive control, I'll look it up....but I'm not too familiar with the theory with these modules yet since they seem to be from the synth world...
DeleteI've built a single module pedal version of the Colour Palette, the schematic is at the end of this thread: https://www.diystompboxes.com/smfforum/index.php?topic=125734.0
DeleteBasically each Colour Module has a non-inverting gain stage beforehand and an attenuating stage after it. Peterson over at DIYRE has set this up using a dual-gang potentiometer so that the amount of pre-gain added going into the Colour Module is countered with equal attenuation on the output. Quite clever!
I've also built a perfboard pair of the 500-series Colour Palette with 3 module slots. It sounds really nice, I love the TM79 Tape Saturation Colour & the XQP Colouruptor. I'd love to build a single-supply 9V version, but it seems like some of the modules really rely on the large voltage swings of the +-15V supply.
Mostly from the studio world, if I can get nitpicky ;)
ReplyDeleteIt's losely based on tape recorders, and aims at reproducing their sonic signature.
The module is designed to be housed into a frame/rack (a bit like the 500 format for eqs, compressors, etc).
That's true that it's quite unusual not to have any knobs, ah ah :)
The gain & levels knobs seems to be featured on the frame only (the modules being *inside* the frame).
The origins of this circuit are a bit lost now, but you can find an archived version with it's own saturation control here: https://web.archive.org/web/20090211142959/http://home3.netcarrier.com/~lxh2/tapesat.html
DeleteThe basic signal flow is Pre-Emphasis -> Soft Diode Clipping -> De-Emphasis. Based on the RIAA EQ curve that boosted highs going in to tape to make up for the poor fidelity, then cutting them before playback to restore the original sound character. The non-linearity of magnetic tape results in pleasant compression-like saturation, which can be kinda reproduced with a ladder of Ge diodes.
So, here is the schematics for the frame/rack circitry.
ReplyDeletehttps://cdn.shopify.com/s/files/1/0698/2265/files/Colour_Palette_mkII_Rev_E_1.0.pdf?v=1586792843
I guess it is essential for the module circuit to work so I guess the layout needs an update or should wesimply add a separate layout for the frame circuit only?
Thank you Fuzzhead and CrackinTheShat for your findings!
ReplyDeleteA layout for the frame would be fine for me (as if the module sounds great, it could be nice to expand the collection, eh eh).
Also, by looking at the schematics CrackinTheShat provided (https://web.archive.org/web/20090211142959/http://home3.netcarrier.com/~lxh2/tapesat.html), it seems like a simpler version to try (as it doesn't require the frame, and uses a single opamp instead of several transistors).
ReplyDeleteAlso, I guess that R1 and R5 are the input and output pots in this schematic, right?
I took the circuit diagram and parts list, and tried to gather them :https://i.imgur.com/873GcaD.png
Deletewow...that looks so much easier to do! I think you are correct regarding the pots and R4 can be an internal 20-50k trimpot...
ReplyDeleteI guess the op amps can be any low noise type or some OPA**** devices for that audiophile vibe ;-)
This will layout will show up in a seprate post. I guess I will add an onboard charge pump as well...
Excellent! Looking forward to it, then ;)
ReplyDeleteThis page references the soft clipping circuit in the Tape Saturator and offers a 2N7000 Mosfet clipper in emulation of the FATSO (Full Analog Tape Saturation and Optimizer).
ReplyDeleteMight be an interesting mod to try out.
https://rdmv.tumblr.com/post/61751110244/i-had-some-interest-in-my-super-soft-clipping
Interesting, it gives further advices about buffers, and opamp : "For this circuit to perform at its best, I would recommend placing a low output impedance buffer at the front of this circuit, and a high input impedance buffer after the circuit, a single NE5532 would be ideal for this job."
DeleteI've taken a look at this before, but the diagram confused me. The 4 transistors on the left side are in series as diode-connected transistors: Drain+Gate-->Source-->GND, but the right side look like they are connected Drain-->Gate+Source-->GND. Is that right?
DeleteAnyone know if this would work well as a guitar pedal? Some kind of "always on" thing?
ReplyDeleteThere is no reason it wouldn't work (given the input level and impedance are ok). It hasn't been designed for guitar, but with a bugger and an input gain pot I think it should work fine.
DeleteAlso, it might be a good idea to tweak the frequencies a bit (the bass bump happens below 100Hz, and the treble emphasis around 2.5kHz : so it's great for a mix, or drums, but might be less noticeable on a guitar).
You'll need to add a high-impedance input with some gain in order to plug a guitar in and still get good saturation. I made this single-module host circuit for that: https://i.imgur.com/7M7EGOp.png
DeleteYou should be able to plug in other modules as well. I've tried a few of them and really like the TM79.
A small headsup. Added a simplified op amp version with no need for an external rack circuit.
ReplyDeletehttps://dirtboxlayouts.blogspot.com/2021/04/tape-saturator-diode-compressor-op-amp.html
Will eventually add the rack circuit to this post.
Thanks for doing this one!
DeleteWould there be any chance of you taking a look at the Distortastudio and Colourupter they do as well?
Cheers
I'm quite interested in the Distortastudio and Colourupter as well so I will take a look. But as I said, these modules probably needs an external rack circuit to work.
DeleteMan I'm glad I found this blog as we have really similar interests! I've made a pedal version of the Colouruptor, but only ever as a perf layout, so it would be great to have a vero layout (which I prefer, but suck at laying out).
DeleteYou can find the schematic here: https://i.imgur.com/mUAGyEv.png
And the original FSB thread here: https://www.freestompboxes.org/viewtopic.php?f=7&t=30848
The guys who designed the Colouruptor (XQP) also run a small pedal company called Trip Hazard Effects. They used to make a pedal called the Disruption, which was based on the Colouruptor but ran on 9VDC. I made some changes, like replacing their expensive Virtual Ground chip with an opamp buffered Vbias. A correction to the schematic is that any ground references before C2 or after C10 (so input GND/output GND/R2/R11) need to reference actual ground - i.e. DC jack center pin & input/output sleeve). The other ground references inside those 2 caps are all referenced to Vb from the buffered bias. I didn't do that originally and my switch had some almighty pop every time I hit it.
Very cool circuit! Good job on the schematic and thanks for all the info. I have started a layout on this. Just need to get used to the power supply arrangement.
DeleteJust to clarify the connection to the DC jack...
9v is the same pin as normal?
Ground to middle pin? Can it be daisychaned to the audio jacks?
-9v to pin where you normally connect to ground?
Yeah, the DC jack & Input/Output jacks are all like a normal pedal, with the grounds daisy-chained together. It's only the circuit between C2 & C10 that use Vb for ground.
DeleteI found the schematic file and updated it with "Vb" for any ground referenced to the opamp buffer: https://i.imgur.com/s1udSQu.png
It looks like the previous version I posted had the wrong value for R9. It should be 7.5k, not 16k.
Thanks. I will upload the layout shortly including a small diaagram for the DC jack wiring. You can give a comment there if you see something that is messed up....
DeleteII haven't had time to investigate further my build of this circuit yet, but i'm just chiming in to say that i'm glad too having found this blog :)
ReplyDeleteJust got a private message regarding this build. It works perfectly using a FET booster upfront. So I'll tag it and I'll add notes to the post about the booster.
Deletehttps://dirtboxlayouts.blogspot.com/2020/09/fender-blender-3-knob-booster.html
Without the FET booster it sounded "without life" and it had too much hiss. Now it sounds perfect. I added a rotary switch to ground the first pair of germanium diodes, the first two pairs, the first three pairs and all four pairs of germanium diodes. Now it can be used as a transparent overdrive. Thank you, again, fuzzhead!
DeleteI appreciated your work very thanks tape storage
ReplyDeleteQuestion... I never built this in the end bit considering it again...
ReplyDeleteWouldn't simply changing the two 100K resistors to pots act as the input/make up pots instead of using a fet booster? The layouts very similar to the op amp version.