This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Thursday, October 18, 2018

Hughes & Kettner Red Box Mk. II

Here's a nice utility box for home recording or even live application (if you've run into a sound guy who hates guitar amps 😠). It's a direct box but also a cab sim (4x12). It won't run off phantom power, so just power it with a 9v wall wart or a battery. Also, connected to the Speaker In pad should be another jack for "speaker through" (so you don't blow up your amp). Here's the schematic and original user manual for reference.



Update Nov. 15:
I removed the extra components for ground lift application as most reported it not working and they had better success with placing an on/off switch between XLR pin 1 and ground. YMMV

49 comments:

  1. Will you made 2nd ver with phantom power?

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  2. The layout seems to be lacking the "speaker through" jack that appears in the schematic. You could fry your tube amps output transformer, if you plugged it in this without a proper speaker load!

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    1. Info added to the original post. Thanks for reminding me about that!

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  3. Ground/lift spst is wrong i thing...
    Closed switch XLR1 must be direct to ground.. and open switch XLR1 bridge to 100n & 10 ohm to the ground...

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    1. I think so too: http://www.patentsencyclopedia.com/imgfull/20150087187_09

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    3. Hmmmz, although I also found this: http://stompville.co.uk/?p=359, but look like all ground should go to the RC couple and then to ground instead of the construction here that XLR1 only goes to the RC and then to common ground. Any thoughts?

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    4. And then there is this: http://sound.whsites.net/articles/mic-splitting.htm#s8
      same as in the layout except that the RC network is always connected to XLR1 and ground and the switch only connects XLR1 to ground.

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    5. and finally: http://www.epanorama.net/documents/groundloop/groundlift.html

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  4. I relayout this.. and put some resistor & diode for phantom.. its work

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    1. Hi, can you post a picture of your layout? very interested in this...

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  5. This circuit cannot be direct from instrument, line in is mean the signal come from preamp out.
    So we need some preamp before line in.

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    1. can it be like pedal preamp? or just head amp?

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  6. Hello! Why are the 1UF capacitor drawings so big? Are they polyester? Are more than 16V?

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    1. hi, they're not electrolytic. yes they can be polyester

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    2. Thank you very much for your answer!!!

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  7. And for those who want it, here is the manual:
    http://oldies.hughes-and-kettner.com/Red_Box_Mk%20II/REDBOXMK2.PDF

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    1. oeps... sorry, was already in the original post :)

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  9. Я сделал этот макет и он работает! Всё в порядке. Вместо TL062, я использовал попавшиеся под руку TL072, но позже я заменю их на TL062. Я собрал без переключателя, потому что здесь есть небольшая ошибка. В положении А штекер №1 должен идти на землю, в положении №2 всё правильно через резистор 10 Ом и конденсатор 100uF. Так же вместо разъёма XLR я поставил обычный Stereo Jack, но позже я его тоже заменю на XRL. В наличии просто не было)) Если кому нужны фотографии, то есть несколько - пишите.

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    1. English? But ok, google translate was my friend :) I agree there is a mistake in the groundlift. PS I hope u used a 100nF and not a 100uF.

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    2. Yes, 100nF :) But I removed these components and installed a simple jumper from the XRL 1 to the ground. And added a light indicator.

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    3. This https://yadi.sk/d/aZwDPQBqRM6Jwg

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  11. can we use tl072 with this circuit?

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  12. where is the ready for transfer?

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  13. Hi i did not find transfer image in library kindly help.

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  14. For use with bass need some capacitor changes?

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  17. Hi i have made this and working but very low output kindly help, to increase output i have removed input ground 10k resistor it increased some out put but still very low and hissss sound is coming anyone can help me?
    Thank you.

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    1. It must be conected to a mic input

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    2. hi tnks, but i have connected this circuit to xlr mixure input and problem remains same in xlr input thats why i need help, i have used tl072, diode 1n5819, 68nf tantalum and removing ground to xlr 1 creates horrible noice so in my circuit it is must to ground always connected, i have checked all resistors are properly connected.

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    3. ok, you need a line level input or output of amplifier as user manual explain. If you are conected like that maybe is a problem in the pcb or even a bad CI.

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  18. I have used TL072CP ic and can be reason for low output?

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    1. ok, you need a line level input or output of amplifier as user manual explain. If you are conected like that maybe is a problem in the pcb or even a bad CI.

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  19. i was looking out the manual and i have a very important question... its just for guitar amp? or can i connect it at last of my pedal chain and use it to go direct to pa/mixer?

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    1. You can connect it to your pedal chain and run it to the PA. Though I would suggest putting some sort of preamp before it.

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  20. Replies
    1. Cool.
      And what to do with line in and speaker in? Sud we connect speaker directly?



      Can u elaborate im quite dumb in this DI thing

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