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

[Branimir]

Just perfboarded this one couple of hours ago, and debugging it (bad wiring around the bass pot).

I don't get much distortion out of it, only mild breakup, maybe because I'm using BF245A transistors... Would J201 really make that much difference?

Anyways I'm trying to get this sucker to fuzz out, and since I don't get much fuzz for now, I tried to boost the front end (with a flipster heh), and yes, it is promising! Nice breakup with loose lows...

I have ditched that treble cut network at the end, still thinking should I have put it anyways.

I'm trying to get this circuit to work nicely as a fuzz pedal, and so far, I think it has potential, that 68nF sure helps lows not to sound tight...

I have looked at various Orange schematics and while that Matamp Green is the thing I'm trying to err.. mimic, I have decided to alter Nelson's Orange Citrus in some things that I thought are important to the classic Green sound.

The tonestack is basically a pre 74 Orange type. Geert posted some unreadable matamp schem on the forums and it looked also that it has the same values in the tonestack. Also, unlike post 74 Oranges, the tonestack is after the second gain stage, if someone can enlighted me why there is a difference between that position or after the first gainstage, I would like to know heh...

Comments, inputs, appriciated...

edit:
Okay, I've debugged it, the tonestack works now great and the circuit has some mid gain fuzz tone, it sounds really good, any ideas how to get more distortion out of it? Ditch the 100k before the gain pot?

[nelson]

Nice!!

Why not replace Q4 with a FET mu-amp?  Then add a fet buffer on the output. It's one less trimpot and I think it would deliver a cool sound. Sort of like adding power amp distortion on top of the preamp. Take the feedback network after the mu-amp.

I would use J201 if you wanted more fuzz especially Q1, Q2 + Q3.

Alternatively you could add clipping diodes after the boost section - that would surely get you into fuzz territory.

[petemoore]

  Looks to me like 3 and 4 could use gate bias resistors.

[Branimir]

You mean like 1M to the ground from the gate of Q3?

Nelson, when you say mu-amp, you're referring to the two transistor connection like in Thor's Q3 and Q4?


Nah, I won't put diodes in it. I'll order tomorrow a batch of 100 J201's and when they arrive I'll try them, I have sockets installed, so easy change there. Later I'll try the muamp design at the end to hear how that sounds...

Why buffer after the muamp?

[nelson]

You mean like 1M to the ground from the gate of Q3?

Nelson, when you say mu-amp, you're referring to the two transistor connection like in Thor's Q3 and Q4?


Nah, I won't put diodes in it. I'll order tomorrow a batch of 100 J201's and when they arrive I'll try them, I have sockets installed, so easy change there. Later I'll try the muamp design at the end to hear how that sounds...

Why buffer after the muamp?

Yep, that's a mu-amp. You have to buffer afterwards because of the output impedence of the mu-amp.

Just use something like Jack Ormans Jfet Buffer or duplicate the output stage, you could also use an opamp buffer, you'll have the vref already from the mu-amp.

You have the 220K Gate bias for Q4 and the Bass pot for Q3.

By moving the tonestack to the second gain stage you are not allowing for as much recovery gain and therefore less fuzz.

[Branimir]

I'm back from band practice, didn't test the Flipster, but I did try the Green Citrus...

Think I'll put the high cut network at the output of the circuit from other ROG type circuits, overall it didn't sound that much good as with my small amp, the big one is Hiwatt Custom 100 clone and I have treble on min to get rid of excessive treble and the Green Citrus was still too ear pearcing with highs...

Back to the drawing board heh... After the arrival of J201's, I'll try the muamp after the second gain stage...

[nelson]

Change the 10ú on the boost pot with a 22ú - 47u too.

[Branimir]

I've updated the schematic, I still call it a V1.0 for now.

I have added the high pass filters from ROG type schems - sounds better this way, the excessive highs are cut, the 15k/2n2 networks, also the cap connected to the Boost pot is 22uF (didn't have 47uF, but I will place that one for sure).

The circuit works well, with BF245A's it's not a hi gainer, more of a low/mid distortion, the boost can be ommited, just use a 600ohm resistor instead of that 1k5 connected to the ground, and use 47uF in parallel to it - its the same thing as if you turn the boost pot all the way up.

If anyone is building this at the moment, try J201, please let me know how it sounds!



Sorry no perfboard layout yet! I improvised while perfin' so its a bit a mess to reverse the perf traces now heh.

[B Tremblay]

It looks like there would be an effect on the bias of Q3 and Q4 since the feedback resistor has no cap in series with it.  Is this the case?

[nelson]

It looks like there would be an effect on the bias of Q3 and Q4 since the feedback resistor has no cap in series with it.  Is this the case?

Wouldn't this produce some nice gain sensitive assymetry on the output?

[Branimir]

I've put a 68nF between the drain of Q4 and 15k as suggested - the circuit works better now, kinda "tighter", and boost function is not so dramatic as before, thanks for your input.

[Branimir]

Hello everyone!

I'm back with the soundclips...

I built the multicab sim from dschwartz so I figured I could do some fast clips of the green citrus...

Bear in mind that this is all BF245A unit for now, so there's not much gain from it...

Okay, here it is:

Guitar= Edwards goldtop 56' LP copy, mahogany 1pc body and neck, maple top, Seymour Duncan P90's (SP1-90 i think), 12-54 d'addario, guitar is tuned to C, the tuner is calibrated to 432hz but I haven't tuned my guitar since couple of days so it could be little off
Green Citrus = 68nF in feedback loop (drain of Q4 to 15k)
Multicab sim = have no clue how it's set up, I just turned the pots until I got pleasant audible results
Soundcard - EMU0404 PCI version

Guitar + Green Citrus + multicabsim + soundcard

gain is maxed on the green citrus for intro of the clip, later i turned it down, played some "clean" passages (i'm a bad player heh) and at the end, it's maxed out again, there is no software manipulatio, recorded, then amplified to 0db, call it normalize, i haven't used any software eq or compressors!

http://www.box.net/shared/ssa9jp8yro

Some people will recognize Sleep's Dopesmoker in the audio file, well, basically I'm trying to push this design to sound as close it can to the mentioned song heh..

And a quick Axis Face into whole thing clip (couldn't resist it!!)
fuzz max, vol 12oclock, citrus is set to clean

http://www.box.net/shared/y8eloh70g0

can't wait for the J201s to arrive...

[dschwartz]

oh! that sounds great, very dark!

by the way, nice work on the multicab, it sounds like it´s doing its job...

[Branimir]

Quick repost...

clips!

http://www.box.net/shared/erntx428h1

guitar+green citrus+multicab sim+onboard soundcard

J201's in all positions now, and drain voltages are as follows:

Q1: D=4.05V
Q2: D=5.18V
Q3: D=4.61V
Q4: D=5.00V

I tuned the trimmers by ear, heh, there's alot of dirt coming from the circuit, I like it...

This is the final schematic for the Green Citrus V1


Now I'll try the V2, first two gain stages will stay the same, after that, the muamp and a fet buffer afterwards, and then A/B test with the V1!

[Gila_Crisis]

sounds cool!
rock'n'roll from doom!

[nelson]

That sounds awesome.

[Branimir]

Heh thanks for the comments, I can't believe I managed to get it work from the first time, and the perfboard was done on the spot while soldering, I didn't have any template.... But flipster's perf layout could be used for guidance, it's not that much different...

[arawn]

yeah definitely sounds like doom, Pretty cool!

[mnordbye]

I really like the dark and doomy tone of this project of yours! Love the Orange amps, though i can't afford the real deal..

[Derringer]

Did you ever try this with the mu amp?

Does this look like the correct way to implement a mu amp?



nice design btw ... I might have to tackle this at some point in the future