Wednesday, 8 October 2014

Ruby Tuby

Request.  This is based around the Runoffgroove LM386 Ruby, but with an IC preamp, into a 12AX7 section, and then into the LM386-N3 power section.  Sounds pretty good in the clips which you can hear at:

http://www.sophtamps.ca/mambo/index.php?option=com_content&task=view&id=28&Itemid=39

This needs a 12VDC supply, so if you're using an unregulated one like the one mentioned in the circuit information then you may want to include a 12V regulator to stabilise it.



65 comments:

  1. Nice! It's version 1.1 isn't it?

    grtz

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    1. Same version in the schematic on that page, V1.2

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  2. Does output work as a speaker jacket?

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    1. Yes it's an amp, so a speaker jack

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  3. Awesome. Thanks Mark. I've been thinking of this one for awhile. I was thinking maybe one of the "amp-in-a-box" pedals put in front could act like a preamp/tone control. Do you think that would work as I'm thinking or would there be a better way to get some tone control out of this puppy? Or is it not even worth adding a tone control to such a small wattage amp? Cause I thought it would be cool to put like WIIO in front to get the tone controls of a hywatt, and box it with a small 8" speaker to get a small amp to test pedals.

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    1. It would certainly work but how useful it would be remains to be seen, it depends how the 386 reacts with amp in a box circuit, but you won't get a lot of volume or headroom I suspect. Better to test it first with the stompbox in front of the amp as is I reckon so you can find good matches.

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    2. Sounds like a good idea. I just find it pretty interesting that there are all these tiny 1-2 watt amps that would make a great little practice amp, so you don't have to wake everyone to test a pedal, but almost none of them have a tone control. I guess it's not super important to have, but I just think it's always nice to have the ability for tone shaping.

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  4. I built the ruby amp a few years ago into a 2x6.5" cabinet (loaded with a pair of 4 ohms old car speakers in which I disconected the tweeters), is sounds good but lacks gain so this version should be pretty interesting !
    http://nsa26.casimages.com/img/2011/01/03/110103124528210242.jpg
    http://nsa26.casimages.com/img/2011/01/03/110103125215295222.jpg
    http://nsa26.casimages.com/img/2011/01/03/110103125247478223.jpg

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  5. I breadboarded this a while ago and it sounded pretty good IIRC. Apparently I wasn't inspired to go out and build it right away. I only have 12AU7 tubes and it worked but would probably sound better with the 12ax7 I'd imagine since thats what it was designed for. This is an excuse to get more tubes ordered I guess... I may try out this vero sometime soon.

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  6. In the text (http://www.sophtamps.ca/mambo/index.php?option=com_content&task=view&id=28&Itemid=39) it says that pin 5 is connected to ground.
    Does the white 5 on the Vero also connect to Ground??

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    1. Yes, if you look the white 5 wire is connected to the same row as pin 4 of the TL072, which is the ground pin. I'd have connected pin 4 to the board as well if there was a clear connection to one of the supply rows. There wasn't so I just included it in the notes.

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  7. Nice! I'm going to give this one a try.
    How do i include a12v regulator?
    Im new to this-learning something new with every build! Thanks for all The Great layouts!

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    1. Regulators have 3 pins, input, output and ground. So the supply from the adapter goes to the input, the output goes to the 12V connection shown on the board, and ground is grounded

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  8. Just one more question. How do I connect pin 4 of the TL 072 to the 12 V?
    And were is pin 4 located on the opamp? Is it the left of right top lug?
    Does this mean I have to connect a wire between the 12 V and the Lug of pin 4.
    I don't quite understand it.

    Thanks.

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    1. Not sure what you mean. 12V needs to be connected to pin 4 of the 12AX7, not pin 4 of the TL072. All connections required to the ICs on the board are already made in the layout.

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  9. So,i make a small daughter-board for The regulator,take a wire from the dc-jack to daughter-board in. Then from regulator out to board 12v-correct?

    Thanks!

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    1. You need to connect ground on the regulator to ground somewhere as well. I believe the regulator is going to want a couple volts from the power supply for stable 12v regulation and the regulator may need a heatsink.

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    2. Ok-thanks for the reply!

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  10. To Lvlark,
    Does this mean pin 4 has to be connected to both the 12AX7's?
    The numbering on the tubesocket goes it from 1 to 9 clockwise or anti clockwise?

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  11. Got you, Know I understand. I assumed there were 2 tubes.
    Thanks.

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  12. Just wondering if anyone has got this working. I have checked mine 3-4 times and get no amplification and only electronic noise?

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    1. Are you able to take voltage measurements at each of the IC and tube pins and post them? Also make sure there are no tiny bridges between the tracks and that the copper traces on the cuts are fully severed.

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  13. So is this not verified yet? I just got my tube today I'm going to attempt this build soon

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    1. No Verification yet. You could be the one!

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  14. I hope so. I just looked at my parts and I only have the 386 n-1 and the 386m so I'm gonna try this out later tonight but I know in the build documents he said the n1 didn't work so I'm gonna build it later tonight and see what happens

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  15. I've got signal coming through but I'm getting a lot of noise it sounds like ticking. Voltages are as follows:
    386
    1: 1.3
    2: 0
    3: 0
    4:0
    5:6
    6: 12.16
    7:6.1
    8:1.374
    Tl072
    1: 6
    2: 6
    3: 5.31
    4: 0
    5: 2.4
    6: 2,4
    7: 1.4
    8: 12.15
    Tube
    1: 3.1
    2: -.58
    3: 0
    4: 12.15
    5: 0
    6: -.58
    7: -.58
    8: 0
    9: nc

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    1. The first time I fired it up I was getting no power and found a cut that wasn't fully separated. Once I fixed that it worked but with oscillation as noted. I wonder if I sent 12v somewhere it wasn't supposed to go and fried something. I'll try swapping ICs when I get a chance.

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    2. The voltages on the TL072 look ok, but my concern is the 386 which has a maximum voltage capacity of 12V, and so if you're using an unregulated power supply without the regulator part of the circuit, I don't know whether that will damage that IC. At the very least I'd have a 12V zener from supply to ground

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    3. I believe the supply is regulated. It is a repurposed wall wart but anytime I've metered it I get right around the 12.15 when not connected to anything. Is that enough to kill the 386? I'll try the zener, swap the 386, and do a more thorough debug and see what I can come up with.

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    4. According to the datasheet the 386 should be good with supply up to 15V.

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    5. I swapped the 386 and checked over all my tracks, cuts, layout accuracy and it all seems to be good. I'm getting motor boating if gain or volume are turned up more than 1/4. When playing notes the decay kind of fizzles out.

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  16. You need a decoupling cap. I put a 470uf from 12v to ground and it's not making weird noises anymore. I'm not sure of the minimum size cap that could be used but I just stuck a big one on there since the schematic calls for a 1000 Uf. I'm still getting a lot of hum but it's just from not having it in an enclosure and being able to properly route the wires. Other than that I'd say the layout is VERIFIED. This amp gets pretty loud even on the 3.5inch speaker I tried it out with. It sounds good. I tried it with both a 12au7 and 12ax7 and both sounded good with noticeably different character.

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  17. Hell yea it's verified. You just need to add a 1000uf cap to the input and a 1000uf cap to the output of the voltage reg. Both to ground. It sounds killer. I've had this schem drawn in my note book for months. Thanks for doing the vero for it. And thanks for the other 50 or so pedals I've made.(or attempted to make) from your glorious blog. I never could thank you enough.
    TS

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  18. Awesome, thanks guys, I'll add the cap and tag it

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    1. Thank you for another great layout!

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  19. On the one I built. I actually used 2 caps. One for the input and one for the output of a 7812 voltage regulator. The schematic calls for a 78L12. But the 7812 works just fine. The data sheet for all 78xx V.R.s suggest using two fairly large caps for the in and out to ground. It might be helpful to add a daughter board to the layout. The 1000uf caps I have a kinda big so the board ended up being 11x6. Also added a very small heat sink. Maybe overkill but I have made almost every 386 amplifier on the internet. And I always use 8 AA batteries. And with tube ones, you really need a voltage regulator because with brand new AAs, 8 of them can be anywhere from 13 to 15 volts or more. This not good for the tube heater which is only supposed to get 12.6 max. This also may help with the noise issues. Again, thanks Ivlark. I am so glad I found this blog. I've been a lurker for a little less than a year. Today was the first time I ever commented on yours ( or any other blog for that matter). I just want to say thanks. And GO HOGS BEAT GEORGIA.
    TS

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    1. Great information. Welcome to this excellent blog! What is the battery life like with 8 AAs? I think I'm going to plan on building a regulator board into my finished build.

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    2. The problem with regulators, and the reason why I didn't include one in favour of a regulated 12V supply, is the input voltage recommendation. For the 12V version they recommend an input voltage between 14.5V and 27V so as a minimum 2.5V more than the regulated output. So if you have a supply that is only putting out maybe 12.5V to 13V the results from the regulator may be inconsistent and/or unpredictable.

      So ideally if you want to regulate it yourself you'd be better off using a 15V supply to be on the safe side. If my supply was between 12.5V and 13V I'd just stick to a 12V zener between supply and ground to limit the supply slightly.

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    3. I think I have a couple "12v" wall warts that put out closer to 15v I'm planning on trying to use one of those for my completed build. I just have a 12v regulated one that I typically use for testing 12V effects since I haven't had any problems with noise on that one.

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  20. Well I fired mine up too. It works, but the sound is not consistent. I sounds like the sound has been scrambled. It that the oscillation I could be hearing?

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  21. This comment has been removed by the author.

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    1. There is not much clean, maybe the bottom 1/4 of the gain channel, not much headroom for a tube running at 12V. Is it making noise all the time or just when you play? You definitely need a large value cap from 12v to ground as mark has now incorporated into the layout. Before I added the cap, the decay was fizzling out is that what you are describing? From your description, it probably is oscillation. Have you added a cap from 12v to ground yet?

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    2. Hi Luke,

      You are right about the headroom.
      It only makes noise when I play. The sound fizzles out (like driving a car on a bumpy road). I can't explane it better (since English is not my native language).
      I don't have an other value cap at home. So that gonna be next week.

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    3. How must i connect the 1000 Uf cap?
      The minus to ground and the Plus to the 12 V?

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    4. Yes, but try a lower value if you have one. Anything around 47u or above may be fine.

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    5. I have another question. Is it wise to put a (1N4001) diode between the 12 V and Ground. If so must it run from the right top (12 V) to the left bottom (ground).
      Just to be sure the current does not go backward (because lots of effect have the diode placed).

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    6. I don't think that would be a good idea, parallel reverse polarity protection diodes are a ridiculous idea unless used with an appropriate fuse. They will burn up or explode under reverse polarity and take chunks of the board and other components with it. Personally I'd prefer to run the risk that I won't be daft enough to put in the wrong power supply, and maybe have to change a couple of electrolytic caps if I do rather than include something which I know will cause damage.

      Putting a diode in series with the supply is a much better solution. Yes you get some voltage drop (although if you use a schottky like a 1N5817 that is minimised) but under reverse polarity it just won't conduct and so there is no damage.

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  22. Sorry Luke, I have not had a chance to answer your question about how long AA batteries last in this circuit. Well, not that long (the tube is the main culprit) but, to me it's worth it for the option to be portable. I add dc jacks to all the 386 amps I make. In other 386 amps the 8 AA packs do a whole lot better. Like the Noisy Cricket (all hail Dano Beavis) or the original Ruby. But my favorite is from Paul in the Lab. Lots of gain. And you can add any stomp box circuit for a pre. As for the sound of this one, I tried so many tubes and found that a 12ax7 doesn't sound that great but 12au7s and 12at7s sound way better. Especially older ones. Right now I'm in the process of hooking up a Tonemender to this bad boy.

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  23. I forgot to mention I'm using an old Tascam Portastudio wall wort for the dc jack. It's says 12v DC but put my voltmeter to it and it's 18.2! WTF! Now I know to always test those little M.F.ers before I plug them in. The voltage regulator is working great in this instance. Giving a comfortable 12.06v. Although, I will be mindful that
    VRs need at least 2.5v over the regulator to regulate. Thanks, I am still learning.

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  24. Mine works ok with the 1000 u Cap, but it sound like a Baritone on the D, A en E string.
    Just not clear. Can this be explained and cured with an extra of different resistor or cap?

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    1. It shouldn't sound like that, make sure you have all correct values for resistors and caps. Also make sure there are no solder bridges, and double check correct placement of links and cuts etc. When you say baritone what exactly does that mean? Is it a sort of farty sound? Does it just sound like the tone is rolled off? Further description may help with troubleshooting. Also, it may be helpful to take voltages at the ic pins and tube pins. That's about all I have for troubleshooting advice.

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    2. It's hard to explane the tone Baritone. The sound does not sound clear, more like a octaver.
      the components are ok, also checked solder bridges.

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    3. Hmm I'm not sure. Hopefully someone else will chime in soon. What type of tube did you use? Is it a known good tube?

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  25. Try a different tube. In my opinion, a 12au7 or 12at7 sounds way better in this amp. There is not enough voltage to satisfy the plate of a 12ax7. After playing with this for a few days I'm not so impressed. I added a ROG Tonemender to it. That helped. But still not enough. There are better options on the web. The best one I have found is from Paul in the Lab. It's just a 386 amp with no controls. I just put a Valve Caster in front of it (veroboard for it on this site.) It sounds very good and has gain, tone and volume controls. I run it at 12 volts as well.

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  26. I leave it as it is... It was just for fun to build and try.
    I started the build of the Runoffgroove Tri-Vibe(also vero on this site).

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  27. I do like my Ruby Tuby. It's just that I couldn't get it to sound as good as I would have liked with a 12ax7. But it dose sound quite good with a lower gain tube and some type of tone control. That's why I added a Tonemender. Every Runoffgroove circuit I've built has been awesome. Have not built the trivibe yet. But it's on my list.

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  28. It was ment for my son. He wants to start playing guitar. I bought him a Fender Mustang I in statt.

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  29. I'm getting faint high pitched squealing which changes randomly between two frequencies. It can be heard at zero volume but the squealing changes when volume or gain pots are adjusted. Any ideas? Grounding issue? Thanks!

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  30. Also, I'm running this off of a 12v laptop power source but I previously tried making a voltage regulator daughter board based on the schematic from the sophtamps site. I cooked two voltage regulators with what I made, is there a vero layout anywhere for the daughter board?

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  31. Try this http://www.paulinthelab.com/2012/05/lm317-fragment.html?m=1
    Lm317 is adjustable with a couple of resistors. Paul's blog is great!

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  32. Is there any way to calculate the mA draw from this?

    I was thinking about using a 555 voltage doubler board to bring this up to ~17 v, then using a 12v regulator. But, I know that we can only get 30mA from the doubler circuit.

    Am I crazy in hoping I can do this? Or is 30mA plenty to power this amp?

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  33. Hi All.

    Just on the off chance somebody spots this on quite an old design but I'm considering building this but with a headphone socket as well as an out for the speaker. I'm relatively new to this and wondered if the headphone addition from the Noisy Cricket board (http://tagboardeffects.blogspot.co.uk/2012/04/noisy-cricket-mkii.html) would suffice or whether I should be looking at something a bit more sophisticated.

    Any thoughts are much appreciated.

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    1. Just in case it helps anybody else - I built this and it works a treat, including the little headphone circuit too.

      Quite pleased with it for a little practice amp but I'd echo the comments about the bass being a bit "farty" with the gain turned up a little bit. Only real issue for me is some weird ground hum when I run it through headphones without a speaker connected but it sorts itself out when I plug a speaker in.

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