An update to the Orange Citrus MK2... The Green Citrus!

[fuzzo]

What does the boost control ? just add "boost" or a kind of color like a "presence" or "contour" ?

I'll do a similar project , a cool Orange  OTR preamp with something between 15V and 24V . Berfore that, I have to learn more stuff about FET bias.

[rnfr]

very cool stuff!  i love the sound of the green amps, and this definitely gets close!  i tried to get a similar tone out of ge trannies with a circuit i made called the Toecutter.  it's written up on the blog in my sig.  i'm  going to have to give this a shot one of these days for sure.  have you thought of biasing the FETs from the source? 

[Davelectro]

Hi folks,

Sorry to bump such an old thread. I'm about to build this pedal with some mods in order to use it as a preamp. Let's say I replace Q4 with an SRPP stage which has low output impedance (good for driving a chipamp-based power amp). Would the "boost" function design affect in any way the low output impedance capability of the SRPP?

Thanks in advance.

[earthtonesaudio]

Look at what the "boost" pot does.  It bypasses Q3's source resistor (which reduces degenerative source feedback for that transistor; increases gain), and also cuts the signal coming through the 15k/68n from Q4's drain.  This is a negative feedback path, so reducing it increases the gain for the Q3/Q4 pair.
One handy thing about negative feedback is it reduces output impedance, so the dynamic output Z of Q4 is actually lower than the DC resistance of the drain resistor might suggest.  The more the gain pot is turned up, however, the less negative feedback and the higher the output Z becomes.  Using another active device (be it SRPP or a source follower) at this point will increase the overall gain and drive the output lowpass filtering more ideally (note I used the word "ideally" rather than "better," as this is a distortion circuit and tone is subjective).

Additionally, if you want low output Z of the effect as a whole, the best place for a buffer would be after the output volume pot.  The lowpass sections and volume pot contribute to a rather high overall output impedance regardless of the output Z of Q4.

[Davelectro]

OK, then a regular mu-amp stage will do just fine. I'll put a source follower after the master volume pot.

Thanks for the response.

[Brymus]

Hah I passed this over before ,cause it didnt click "Orange Citrus" I was thinking OS clone 

That last soundclip sound fantastic !!!!
Love the Sabbath at the end,nails that dark tone.I think its definetly worth building at some point.
I added this to my ever growing folder of amp sims,

Ya know I still think the FET emulations (alot of them at least) sound better than the digi amp sims in the popular software choices.
For instance that sounds much better than an Orange Citrus amp sim with the Orange cab sim,in a rather pricy software (I had the demo) I tried last month.

[Branimir]

Heh can't believe this thread is still alive

Haven't built fet emulators since this one, but i'm intrigued to try this "orange" type of circuit with muamps, having seen and heard catalinbread's dirty little secret - i'm conviced that muamps could work even better, and not to mention there's no need for trimpots...

Also - the bass/treble tonestack is cute, but if you ask me, I'm in for a single knob tonestack, I remember some time ago - I was looking at the bigg muff tonestack and with a help of duncan tonestack calculator it was possible to get a similar curve when bmp tone pot was in center position - similar to bass and treble crancked all the way on the baxandall...

Gain, Tone, Volume (boost omitted as I mentioned in an earlier post) - it would be a nice distortion pedal in the end. Maybe a switch to change the voicing of the tonestack...

Anyone care to dig into this? I'm kind of lazy, but could put up a schem in a couple of days...

[LabyrinthAudio]

Longtime lurker, first post, and bringing this topic back from the grave! I know there was some talk about output buffers and SRPP's but I'd like to run this with a +24V supply with possibly an output to feed a slave amp. For starters, what components would have to be changed or added for +24V operation? I was planning on building a prototype with the values from the Orange AD200B V3 preamp schematic to make it more suitable for bass guitar.

[petemoore]

  Standout bass-fringe tone ! 
  Deep dark and doomy clips are often accompanied by harsh harmonic nodes that are just too 'sharp' and fast for the curvy and slow bassy-source [harshness appears]...generally bassy-distortion seems to go 'just so far' into harmonic generation before the harsh-edges begin to surface, this sounds to go nice and deep into distortion while maintaining the ability to supress the raw, harsh edges.  Jfets are cool. 2n5457's are fun too, falling somewhere between MPF102 and J201 ...average...gainwise [Jfets vary in bias needs/performance from fet to fet, even from the same part #'s and batch].

[Davelectro]

Longtime lurker, first post, and bringing this topic back from the grave! I know there was some talk about output buffers and SRPP's but I'd like to run this with a +24V supply with possibly an output to feed a slave amp. For starters, what components would have to be changed or added for +24V operation? I was planning on building a prototype with the values from the Orange AD200B V3 preamp schematic to make it more suitable for bass guitar.

Just set the trimmers around 12V and you'll be fine. Also, avoid j201 transistors unless you want extreme distortion.

I would redesign the whole thing to the improved Fetzer Valve specs, though. Far more realistic for a preamp.

[LabyrinthAudio]

Thanks for the responses guys. I realize it will be a little over the top distortion/fuzz wize but to fix that I could add a low pass filter on the output. I was floored by the sound clips, so figured this would work for bass too. I want this pedal to have the ability to go from a nice overdrive all the way to a dark doomy sludge tone while maintaning low end.

[Branimir]

Sorry for bringing this topic 2 years to the front!

I'm back, and with a vengeance!
Unfortunately Orange Citrus got lost in the drawer somewhere and I'm about to rebuild it once again, and this time I'll try to use it with a proper tube amplifier to get maximum results.

I own two Laney's (one GH100L and one VH100R), and I plan to drive the poweramp of one of these with the Orange Citrus MK2, hopefully it'll have enough output to push it, if not, maybe I should try with some sort of boost after the last gain stage?

Anyways, I'll start perfboarding it these days and hopefully put into full test in the next two weeks! Will post sound clips and photos too!

Cheers!

B.

[LabyrinthAudio]

Good to hear Branimir. I successfully built MKII but had some issues with output volume, oscillations, and now it doesn't work....there's 6v DC on the output volume pot, traced the entire circuit, replaced pots, caps, and transistors...oh well. As soon as I'm back from tour I'll give it another go! 

[Branimir]

I have the layout in Bancika's DIY Layout creator, will share when I test it.

I will incorporate switchable hi-cut circuitry that will be located before master volume pot, so it will be possible to switch off the hi cuts that are just before the master volume pot.
Soundclips soon!

[Branimir]

No clips yet, but I've tried it with a big amp.

Have tried directly to power amp in, bypassing totally the preamp and just using the 4x6L6 to push 4x12".

Off the bat I've noticed that the hi cut circuitry is not really needed in this type of application, as it brings down the output of the circuit too much and the treble pot loses it's usability.

There's plenty of gain on tap, especially with boost dimed. Tone controls are as in every Orange, quite limited and this is just a one-trick-pony preamp, delivering thick distorted, almost fuzzy tone.
In a couple of days I will test it with a 4xEL34 amp to see if it delivers true Orange fat tone, because with 6L6 it sounds a bit modern and dark, with not alot of mids, and I think it is capable of pushing the poweramp, at least with the gain and boost and vol pot turned all the way up...

One thing that is missing from this design, that is sort of crucial and a totally cheap trick -> is the FAC control, which is just a switchable coupling cap between two gain stages. The circuit is bass heavy as to the point of saturating the next gain stage too much, with gain maxed and even bringing down the tone pot does not help much. Blocking distortion? Farting palm mutes? That's it. The FAC control would give the control to the coupling cap before 2nd gain stage, and therefore omitting the amount of low frequencies that are passed into the circuit. I imagine lowering the coupling cap (22nF for instance) before the second FET would solve the blocking distortion problem, and give the full range of the bass pot, for those who like to crank the bass all the way

[LabyrinthAudio]

I did notice on my build that unity gain was almost at 3 o'clock on the volume pot. Maybe a mu-amp/makeup amplifier would help here to give some boost? The tone was absolutely crushing though!

[Branimir]

I was thinking of a mosfet gain stage a'la Jack Orman's Mosfet booster

[LabyrinthAudio]

Low current consumption and low output impedance, I like it...but with that many extra components, looks like it would be a pain to implement into the circuit?

[LabyrinthAudio]

OK So after some mods and debugging, I finally got this going. I used the original layout and added a stock LPB-1 right after the output, you can see it on the right side of the board. I set 4.71v for each trimmer but the signal gets kinda gated starting around 11 o'clock via the Gain control. I was surprised when I turned up my amp and didn't get any crazy feedback....probably have to fine tune those trimmers by ear? Or use 12v or 16v supply? Anyways, tried this with my crappy MIM tele through a '71 Sunn Model T and a Sunn Coliseum Lead and was quite literally blown away with thick doomy sludge (hooked up FOUR 4x12's to the coliseum amp, 300 watts RMS @ 2 ohms! Thanks Branimir for this project/inspiration. Would anyone like to hear sound clips or need more info?

[kingswayguitar]

new soundclips for this...yes please. the originals a few years back were very cool. love your sig line btw