Friday, 20 June 2014

Way Huge Pork Loin

[10th July Layout now fixed and verified, many thanks to John who bought and traced an original]

Requested by a few people.  The juvenile in me was so tempted to call this one the Huge Pork Sword, but thought I should start acting my age :o)

This is a fairly big circuit for an overdrive but should still fit in a 125B I reckon.  It seems to be very tweakable with 5 external pots and 3 internal trimmers so should give a wide range of tones.

The 2N2484 transistors aren't very common but can still be obtained from a few sellers on eBay without re-mortgaging your house, but if you don't want to buy anything in specially, just use any NPN transistors around 250 - 400 hfe.  The 2N2484's are metal can with the triangle pin arrangement allowing you to easily mount in any pin order, and you'll notice that to make the layout flow better Q4 and Q7 have an unusual CEB pin arrangement.  Keep that in mind when selecting and mounting the transistors, and twist the pins as required if using a transistor with inline pins.

Info about Jeorge's, and now Dunlop's, versatile overdrive pedal:

Make room for one more Way Huge original! The Pork Loin incorporates two distinct tonal pathways that are blended together—a modern soft clipping overdrive and a modified classic British preamp for clean. At the heart of the Pork Loin’s overdrive path is a soft clipped BiFET overdrive gain stage with a passive Tone control, rounded out by a Curve function that gives the user freedom to fine-tune corner frequencies. The Volume control regulates the masses of pork power that exude from its space age circuitry, leaving room for the Clean control to blend in its warm glistening clean tones. Additionally, the Pork Loin has three internal mini controls: Filter and Voice deliver extensive tonal shaping possibilities, while the overdrive Mix control allows the Pork Loin to be run as a clean preamp. With a wide range of dynamic tones, the Pork Loin is the premier overdrive pedal on the market today!






41 comments:

  1. Whoa, talk about Way Huge, hehehe. Thx for the layout!

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  2. Awesome. i'm going to try to find time to build it later today. thanks!

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  3. Layout updated. I managed to cram it in a bit more at the bottom and save a row.

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    1. cool. well, it's too late for me. I just finished populating the board of the previous one.
      I just need to wire it up now and test it. it'll still fit in a 125B.

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  4. well, time to get out the scope and probe it since it's not working. bummer!

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  5. man, I've scoped it with as signal generator and the gain pot is doing nothing. I've checked your layout against the schematic pretty thoroughly and I haven't found an error in it yet. i'm starting to think that the schematic itself is wrong, but i'm going to keep at it for a while longer.

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  6. Waiting for this one to get verified before I touch it LOL
    Great work though, in the video when they show the guts, it looks pretty crazy and I would love to cram one of these in a 125B if possible...

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    1. On the plus side, even if the schematic is wrong, it's certainly not going to be too far away and so we can just put it on hold until someone gets hold of one to double check everything and then hopefully it'll be a few quick mods and the same layout can be used with minimal fuss. So we'll definitely get there, and John is very good at fault finding so if it is close he may crack it yet! :o)

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    2. i sold an original one about 6 months ago and right right now i wish that i still had it just to compare voltages to the vero.

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    3. What voltages are you getting?

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    4. actually, they all look good. I was experimenting with jumpers on the bottom of the board, and if I jump an 22K resistor across a couple of points, it almost works properly but I know that it's not correct yet.

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    5. Are you getting no sound out of it at all? If you ignore the clean transistors side completely and just follow the overdrive path, where are you losing the signal?

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  7. I'm getting a signal but it's very low. both sides (the clean path and the distortion side) are all messed up.

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    1. ok, it looks like i'm losing the signal at pin 6 of IC2. when I take the chip out, the signal is on pin 6 of the socket, but when Install the chip it mutes it down to almost nothing.

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    2. I think I've spotted it mate. The link going to up IC2 pin 1 needs to go to pin2, and the top lead of the 150K needs to go to pin 1 instead of pin 2. Bet that fixes it.

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    3. Actually I think that may have been correct in the earlier version, it was the version that was 1 row smaller that contained the error? Worth checking though

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    4. the one that I built (the previous 22x33 one) already has the link and resistor that way, so unfortunately, that's not the problem.

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    5. well, I have tried a bunch of things and haven't resolved the problem yet.
      what's strange is that the LM833's last two amp stages seem to be simple inverted gain stages with the first one having a lot of top end cut (to reduce the hiss with the 220n cap).

      next, i'm going to disconnect the last two stages from the circuit and inject a signal into it just to see if that part is working properly without all of the circuit in front of it since I am getting a signal on the scope out of the drive mix trimpot and all of the other controls and trimpots seem to be working properlty.

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    6. Yes I think that there is a small error in the schematic round there. Looking at it and you would imagine it would pass signal fine.

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    7. well, for one, IMO the 220n LPF is way to big since it cuts almost of the signal.
      also, replacing the LM833N's jumper from pin 5 with a 100K resistor also made the amp circuit work (gave me decent level) but both the clean and overdrive tones are extremely muddy and dark.on top of that, there's also a TON of hiss which you would think that there wouldn't be being that it sounds so dark right now. my original wasn't bright, but it wasn't a mudball either.

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  8. Thanks Mark for the layout. Cheers mate
    Vince

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  9. Is there any.chance of seeing the fat sandwich on here soon?I like alot more gain.is this the same as the fat sandwich just with less gain?

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    1. Yes I'll do the Fat Sandwich too. There are some similarities but the Fat Sandwich is a smaller circuit so it should end up pretty compact in comparison.

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  10. Okay, I ended up buying another original Pork Loin and found all of the issues with the schematic & vero and emailed IvIark with the corrections.

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    1. Just read you email, that's excellent mate :o)

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  11. pics of mine completed (and it sounds great!)

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/PorkLoin/PorkLoinclone-01.jpg

    http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/PorkLoin/PorkLoinclone-02.jpg

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  12. I also built this, i didn't have any of the trannies suggested, so I used mps18's for the CEB positions, twisting the legs, and bc109s for the rest. I used a opa2609 instead of the lf353, i find the opa2604 to be clearer, all I can say is WOW, the harmonics on this thing is beautiful, I like this pedal so much I might build another. I must have built about 100 pedal over the years and to me this and the DLSmk3 and the citrus graphic pedal are my fav's....thanks Ivark and John

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  13. I built this yesterday, took me a looooooong time. Probably 7 hours from start to finish (I boxed it too). I also put MPSA18s in the CEB positions, and 5088s in other positions. Sounds great, very warm, perhaps a little dull at times, but very amp-y. That clean channel is pretty ace as well. Do you think I should bother investing in the 2N2484's? I'm wondering how different the response would be. Hm.

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    1. I haven't compared them but the gain of the two types is very different, and Jeorge certainly knows his stuff. I'd try something lower gain in there and see what you think

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    2. Yeah I was gonna say - MPSA18s are really high gain in comparison to the recommendation of 200-400 Hfe of the 2n2484, but it does sound great considering. Ehh, maybe I'll just bloody buy some! It's November after all.

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    3. You could try 2N3904 and/or C1815. Those are cheap to source.
      +m

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  14. stock Pork loins are inherently on the dark side. I sold my first one because I thought it was a bit too muddy. if you change the 1n cap at the lower right side of the board to a 470p, it'll open up the top end but still retain the overall tone on the pedal. I did that mod on my original, and my clone, and it sounds a lot better now.

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    1. Yeah I think I might have to do that. Any tips on increasing the gain on this pedal John? I might just have to try some out I spose.

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  15. Hi, I am planning to build this pedal and I was wondering if there is a schematic as well as a layout for the off board portion?

    Thanks,

    JD

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  16. Hi, if there´s a schematics? I don´t like stripboards too much...:-)

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    1. yeap there is. it's in www.google.com
      the very first image if you search for "way huge pork loin schematic"...

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    2. Thank you, I'm silly, I've tried "pork loin way huge diagram" as used to be...:-)

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  17. I want to build this one, but also make sure I do the cap swap that John K mentions above. Can someone confirm it's the 1nF cap between IC 2 and the 100k resistor on the lower right of the tagboard diagram? Thanks.

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    1. That's the one. It does seem quite large for that position. The other caps in the feedback are 100p. Experiment from 100p to 1n and decide for yourself what you like best.

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