Building the Meat Sphere

[Taylor]

Just finished my build, but unfortunately it's not working.

When the effect is engaged I get clean signal when blend is below 100%, the LED triggers/flashes along with the envelope but I don't get any wet sound. The only issue I can find on the board are with the little holes meant to be left empty to the top right of the 47u cap above the LED (I'm looking at the side of the board with text where the components are mounted). I accidentally lifted the pad on the top of these two holes after trying to get rid of some solder that had fallen into the hole. The lower hole also has solder in it but I didn't attempt to clear this after lifting the pad on the top hole.

Any ideas what could be causing the issue? Unfortunately I don't have a VM/audio proble to hand to post readings/explore where audio may be dropping out myself.

I'm using a pair of vtl5c3/2 vactrols. LM1458N and TL074CN. Any help that you could offer would be hugely appreciated at this stage!!

Those holes are vias - they connect traces on the bottom copper layer to the top. It doesn't matter if you get solder in them, as long as it's not bridging to any other pads to short them together. If you lifted the pad and didn't fix it, it's very likely this is at least part of the issue you're having.

What you can do is run a wire to complete the connection that was lost with the lifted pad. Here's a picture. Connect a wire between the two points that have arrows pointing at them. In case you don't have thin enough wire to connect to the via, you can solder the wire from the optocoupler pad with the arrow, to pin 6 of the TL074. This is connected to that same via - it's farther to run the wire but a larger pad in case you have trouble soldering to the via.

http://imgur.com/37fvNyC

[Fine Mechanics]

Just finished my build, but unfortunately it's not working.

When the effect is engaged I get clean signal when blend is below 100%, the LED triggers/flashes along with the envelope but I don't get any wet sound. The only issue I can find on the board are with the little holes meant to be left empty to the top right of the 47u cap above the LED (I'm looking at the side of the board with text where the components are mounted). I accidentally lifted the pad on the top of these two holes after trying to get rid of some solder that had fallen into the hole. The lower hole also has solder in it but I didn't attempt to clear this after lifting the pad on the top hole.

Any ideas what could be causing the issue? Unfortunately I don't have a VM/audio proble to hand to post readings/explore where audio may be dropping out myself.

I'm using a pair of vtl5c3/2 vactrols. LM1458N and TL074CN. Any help that you could offer would be hugely appreciated at this stage!!

Those holes are vias - they connect traces on the bottom copper layer to the top. It doesn't matter if you get solder in them, as long as it's not bridging to any other pads to short them together. If you lifted the pad and didn't fix it, it's very likely this is at least part of the issue you're having.

What you can do is run a wire to complete the connection that was lost with the lifted pad. Here's a picture. Connect a wire between the two points that have arrows pointing at them. In case you don't have thin enough wire to connect to the via, you can solder the wire from the optocoupler pad with the arrow, to pin 6 of the TL074. This is connected to that same via - it's farther to run the wire but a larger pad in case you have trouble soldering to the via.

http://imgur.com/37fvNyC

Many thanks for the input Taylor. I've fixed the pad but unfortunately no luck. I've  echecked and reflowed all joints on the board, double checked all wiring and IC orientations but still no change. Dry signal when blend is below 100%, LED reacting to the envelope but no wet signal. Looks like I'll need to go'n grab the bits to build an audio probe over the weekend...

[Taylor]

You're welcome. To build the most basic audio probe, you literally just need to cut off one end of a 1/4" cable, and solder a capacitor (100n or so) to the conductor. To probe you just need to connect the shielding of the cable to the ground in your circuit and then poke the free end of the cap at various parts of the circuit. So all you absolutely need is a cap and a cable. The rest just makes it more convenient to use.

[TonyUK]

Hi guys, sorry, TOTAL NOOB here. Desperately want to build the meatsphere and big cheese clone,Ive ordered my pcb from Taylor, But I'm somewhat confused when searching mouser for all the parts. I added what I thought but havnt pulled the trigger on the order yet so I hoped one of you nice people could have a quick look at the basket and tell me if I'm either on the right track or screwing it up.

http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=748d93450d

Thanks guys.

[idy]

One of your pots is "solder lug" instead of PCB mount. You can still use it, just not as easy and the board is designed for board mount pots.

You've already taken the plunge, I hope you have read the threads and know this is a dicey build. It is the only pedal that I have built (more than 50, less than 100) that only sort of works. Good you are buying from reliable supplier as off-brand opamps can cause problems in this.

Consider ordering more than "1" of everything you need.

Consider trying some of the easier filter effects first. Some you can do on stripboard, and there are great pcbs out there for mutron, FSH-1, mxr, etc. Let this one sit until you are used to the process, have debugging skills, have read all the threads about envelope filters and about the Meatsphere.

[Granny Gremlin]

One of your pots is "solder lug" instead of PCB mount. You can still use it, just not as easy and the board is designed for board mount pots.

It's not incredibly pretty and dubious in terms of structural integrity, but that is of minimal concern here considering it's only 1 of, what, like 10 mount points ( 6 pots + 4 switches right?) on this PCB, but it is pretty easy to mod a solder lug pot to work as PCB mount:



more pics and verbal explanation: http://grannygremlinaudio.tumblr.com/post/122438008623/aurora-ross-compressor-w-mods-white-pcb-and

[TonyUK]

Thanks guys, I havnt actually ordered yet so I can easily amend it. Was totally blown away with all the variations in the components that come up in the search, I was like "ok which one is it" I chose the ones that matched the pdf list as close as I could. Just needed a more experienced eye to see if they would be ok. Theres a few bits mouser didn't do like the Vactorals and the 10k resistors which I'm, sure I can source elsewhere.

Really appreciate you giving me some pointers.

Idy, you think the Big Cheese vero is an easier starting point?

[idy]

I don't know, Big Cheese on vero looks pretty complicated. It all depends on your being real careful in making the cuts on the vero, your soldering skills, understanding off board wiring. There are simpler circuits out there.

Don't get me wrong, the Meatsphere PCB is a thing of beauty. Just a touchy circuit. And for a fuzz Cheese source is on the big side for a first go on vero. PCB is awfully nice the first go unless you are doing something modest.

Once you make one that works though, prepare to be hooked. Go ahead and order resistors by the 100...

[idy]

Another tip about ordering: counter-intuitive, but Mouser is not often cheaper than the guys who cater to pedal builders until you order large quantities. Did you check out Small Bear? For ordering a few parts they are often better than Mouser. Tayda is cheap but a lot of times ICs are "not exactly" what you need, generics that are not worth it for something tricky like the Meatsphere. But good for resistors, caps, etc.

Mouser is daunting and most of us have a baggie or two of something useless from mouser 'cause we didn't read the entire description.

[Granny Gremlin]

Yeah, ICs transistors, pots (best selection of values and options like shaft and tab type) and diodes I get from SB - their prices are great even at low qty and they are reputable/reliable.  Tants from Tayda or a local shop I like.  Switches, LEDs, bezels and DC connectors from Tayda or BitchesLoveMySwitches (or Sm Bear if already ordering other stuff).  Enclosures from Sm Bear or Bitches (best price hands down; fewer powdercoat options tho).  Resistors and film/electrolytic/MLCC caps from Mouser (buy these in bulk and you know you're getting proper stuff - Xicon metal resistors or KOA carbons, TDK box film caps now that the Panasonics are disco'd; Nichon low profile electros, Murata MLCCs - all competitive price-wise with the other guys if you buy qty).

Basically, if you're gonna be into this, just go buy all the typical values of resistors, film caps and electro/tants in qty to save (you will go through a bag of 200 10k resistors or 100 0.1uF caps easy; there's at least a few of each on every build).  This will help: http://diy-fever.com/misc/value-statistics/ . Depending on what projects you're building, the right half of those graphs may not be that accurate, but the left half is bang on in my experience.

[chicago_mike]

Hey gang!!!

If you had to choose between watercolor green leds ( VERY lightly green ) or diffused green, which ones would you go with?

[Granny Gremlin]

Depends on the finish of the enclosure.  I just put a waterclear green in an Echo Base, which is diagonally striped with a pastelish green and a metallic mauve.

[Govmnt_Lacky]

Hey gang!!!

If you had to choose between watercolor green leds ( VERY lightly green ) or diffused green, which ones would you go with?

Diffused! All Lovetone pedals except the Flanger and Wobulator used Diffused Green LEDs for the LDRs.

[chicago_mike]

Anybody got a drilling template for this sucker??

[nosamiam]

I'm pretty sure it was included in the project file on the Musicpcb site when I built mine. But I don't see it there now. There's no way I measured all that by hand so I must have had a template. Maybe email them and ask for it?

[Taylor]

Nope, there was never a drilling template in the build doc unfortunately. It's a good idea, though. The problem is that a given template would only work for a single potentiometer style. So really it needs to be 2 or 3 templates to cover the different PCB mount pots with .2" spacing that people use, which don't have the same distance from solder pin to shaft. But that's doable, I'll work on it.

[1878]

There's a drill template on page 2 of this thread. I used it but it was a little bit off for the PCB mounted pots I used. Nothing unusable though. My build is on page 17 if you want to check.

[idy]

One more Meatsphere out of the Fail Pail!

I built this years ago. At first no envelope at all. Replaced generic 1458 with brand name, got an envelope but really harsh "WHAP" at the attack, really not useful. Finally heeded the voice that keeps on shouting "Vactrols bad... make your own with green LED plus LDR 1m..." Think that was Lace Sensor. I put in some home-mades and now it works as advertised.

Funny thing: I have all these assorted LDRs from various projects (tayda, small bear, radio shack) and they all measure over 20M dark. I just bought from several sellers on ebay, specifically 1M, and these also all measure... over 20m. I have a Cheap centek multimeter that goes to 20M (it takes a while) and test them by rolling them in electrical tape. The Vactrols I pulled off the Meatsphere also measure over 20M.

Further Meatsphere question: the dual opamp is not "biased" but everything is referenced to ground. Is this because it is handling DC and not audio? But this is based on the Mutron III and schematics for that (and its derivatives) show it running off a bipolar supply with the inputs referenced to ground, so what gives? If the circuit was a copy these should have been referenced to midpoint... right?

[Taylor]

Further Meatsphere question: the dual opamp is not "biased" but everything is referenced to ground. Is this because it is handling DC and not audio? But this is based on the Mutron III and schematics for that (and its derivatives) show it running off a bipolar supply with the inputs referenced to ground, so what gives? If the circuit was a copy these should have been referenced to midpoint... right?

When I put the project together, I went on the information available, but I agree with you that some elements of this design seem a bit weird. I don't recall if anybody's ever checked this design against a real MeatBall (anybody got one lying around?) so I can't say whether that's because it was designed weird or some detail got lost in the telephone game. If I was going to design my own envelope filter, which in fact I have done, I would do both the filter and the envelope follower differently (and I did) but at the time people didn't want "some filter" but this particular one.

I believe some of the issues people have had with the dual opamp have to do with the way the LM 1458 handles swinging down to ground when powered on a single supply. In this circuit it can work even though the opamp isn't really supposed to be able to sweep down to its negative rail, because ultimately we just need to light an LED and the available output swing with a 9V supply voltage is plenty for that. It doesn't matter too much if it clips given the non-linear response of the LED anyway.

But, looking at it again, I wonder if more consistent results might be achieved with the LM358, which is designed to run on a single supply and can swing down to the negative rail with no issues. If anybody has a working 'sphere and wants to try this out, that would make for some interesting info. I don't have one built up but I'd be happy to get some of the 358s and send them to people to test. Feel free to PM if you want to give it a go.

[idy]

Thanks Taylor. Patience of a saint. I have some LM358 and tried. Worth a spin! Without careful A/B it's hard to say how they are different, but they are.  LM358 surely works and maybe is a little more controllable.

For a while I was looking at making Mutron/Naughtyfish with all the controls... but now I think of just making more Meatspheres. My latest one was much easier. Green LEDs and LDRs.

I like to solder pots onto the board before I have a box drilled to test the board. To make the pots and rotary swtches line up with the level of the box I found I could solder the pots in with the ends of the "pins" just barely level with the component side of the board. Put them in all the way and the pots are too close. Then of course drill or file the holes in the box a little big to prevent stress.