Anybody build their Gristleizer yet, comments on it?

[rainbowdoom]

 Hi there, almost-first-time-poster here, longtime lurker. I didn't know where to post this because it has a few boards in it, but it feels more like super-modified Gristlizer than anything
This box is four of Taylor's boards (Gristlizer, Echobase, Uglyface and Christine) all wired up to three switches to give 8 combinations of effects order. Only just finished it (haven't even painted the white knobs green yet...) so still getting a feel for it.
Main reason for posting is to thank Taylor for these all the work he's put in on these PCBs- they are supreme quality and it all worked first time. Hugely grateful!!

[Taylor]

Whoa! Amazing job. Really cool and funky.

[frrk]

Hello everyone, I am a new-by in this forum and also in electronics.
i have purchased Taylor's gristelizer and finished populating it. After first test i am noticing a wrong behaviour.
At level pot on either ends, i have a whistle.
Also the signal seems not affected in the vca position.
In vcf mode the signal is very much affected and twisting the depth pot doesn't change the high pitched effect.
I may have some resistors value wrong and doubt about the 6n8 condenser couple (those are ceramics with 6.8 written).
the wires to the pots are quite long.
And the trim-pots are linear instead of log.
JFET is BF245 (with pins bent according to the original) which should be the right replacement for the 2n3819.
i use also an icl7660.
Out of those suspected components does anyone had fix similar problems before?
Last; while un-soldering the tl074 some tracks ends got burned away.
At the moment the lfo doesn't work (but it did work when first tried).
Anyone could list or draw the connections points to the tl074
If i do it from the schematics i fear to forget some points and mess some other things that are working.
Please, help me debug this device. Would be great.
Thanks in advance.
Frrk

[Gila_Crisis]

I have a question I just finished building one with the pcb from musicpcb.com.
everything works really fine and I'm enjoy it a lot.
I was only wondering about one thing, the triangle wave setting is a bit weaker sounding compared to the other waveforms.
is that normal?

[Ginsengbob]

Would it be ok to substitute a 6.2k resistor for the 6.8k resistor in the gristleizer ?



Thanks

[Taylor]

Yes.

[Salvador]

Building 5 gristleizers currently. Have tested 3, 2 of them are "functional". An issue I am having is what seems to be a circuit-wide voltage offset. Reading +10.5 to 13v and -7.5 to 5v. Have tried max1044, icl7660 and divided 18v circuit. Is this typical? Has anyone else run across this issue and maybe remedied it? I have been unable to properly calibrate and am guessing this is a reason why.

[Salvador]

I suppose that may be a bit cryptic. The issues that led to the voltage measuring was what seems to be an instability in the circuit. In vca mode it almost seems that the effect is parallel with the signal rather than effecting it. A strong pulse can be heard but does not necessarily translate to the material itself. Tuning of shape and offset seems to only affect the triangle wave-shape. This is most apparent in vcf mode. Triangle can be set to the point of distortion and really sounds more like a saw wave. Seems like this could be from the voltage disparity? Any ideas are more than welcome and appreciated!

[Salvador]

Turned out I had a bad JFET. Still a difference in voltages when idle which seems odd, but then I'm not so familiar with this circuit and a bit of a novice to boot!

[bcalla]

I finally finished mine.  I was actually done in January, but I shorted the LED when I boxed it & didn't get around to finding the problem and fixing it until yesterday.  

It sounds great, but I did notice a problem.  With the speed set to very slow it is possible to hear the wave shapes (I don't have a scope).  It appears that the rotary switch labels on my enclosure are reversed.  Could the fix to this be as simple as reversing all the wires on my rotary switch?  That seems easier than refinishing the enclosure.

[_dB]

Just finished building the Gristleizer from MusicPCB. 

Waveforms look good on the scope. I was worried I had blown the MAX1044 (pugged it into a 16V wart by mistake) but the voltage still reads +9/-9V out of the MAX, so I think it survived.

If anyone else has the pedal, I am wondering if the following is part of normal behaviour:

- In VCF mode: is it supposed to be so high pitched? There is almost no low end; very "trebly", kind of painful to listen to.
- BIAS past 12' oclock results in pretty intense distortion in both VCF and VCA. Is that how it's supposed to work?

In VCA mode, should the DEPTH affect the sound with BIAS all the way down?   

Thanks!

[Johnnyboy]

Just completed the Gristlizer, over here in the UK, using Taylor's board. Thanks Taylor, excellent quality PCB. A couple of years ago, I built the circuit from the original Practical Electronics magazine article but it was pretty hopeless. Now that the 741's have been replaced with modern chips in the circuit, it's successful. Not boxed it yet, as only just finished the wiring etc. Not suffering from the dreaded 'clicking' at all. I'm running a homemade function generator (Maplin kit) though the input with good results.
If you mount the Depth control on the board, you can pick up an extra Ground point from behind the pot ( LH hole, looking at front of controls), should you need it.

[yeahyeah]

Any tips/mods for getting a slower lfo on minimum speed settings?

I'm finding it hard to hear the difference between waveform settings on all but the slowest speeds. I have cal'ed all shapes on scope and everything looks good and sounds gristle-y.

thanks!

[Taylor]

You can make the speed range of the LFO slower by changing the value of C1 - it's the 470n cap to the left of the TL074. Double the capacitance value would make the LFO half as fast, etc. You can even have two different ranges by using a toggle switch to swap between cap values. That would be good if you still want to keep the current fastest speeds.

It's been a while since I listened to this circuit, but I wonder if the waveforms are getting altered because of the Bias setting. I'm no FET expert but to my knowledge, the "linear region" is not really that linear. So the LFO could present a perfectly linear triangle, for example, and if the bias is not quite right, the transistor responds as if it's a lumpy asymmetrical sine-like wave.

But, that "wrongness" that results from setting the Bias to the "wrong" spot is part of the charm of the Gristleizer, and it's why the board lets you bring it out to a panel-mounted pot. There should be an area on the Bias knob that gives reasonably accurate waveforms, although it has to be said that none of this circuit's sections behave like ideal modern versions would.

[geocontrol]

Hi, Can I ask a real newbie question, how do I connect up jack sockets to this PCB? I'm right in thinking I could connect a eurorack style jack socket to the Input and the Output, but only one hole in the PCB, guessing I need to earth the socket to some other common earth on the board?

Sorry if this is really basic, just getting started and realising the limits of my knowledge real quickly..

thanks

mark

[Taylor]

Yes, you would connect the tip connection on your jacks to the input and output pads on the PCB, then connect the sleeve (ground/earth) pins from the jacks to each other, and to the ground pad on the board. Basically you just need to make sure all of your grounds connect to each other.

Technically you can use the front panel to connect grounds in a euro module, if the panel is metal. But, I don't recommend it because you will get intermittent connections if the jack ever loosens.

[geocontrol]

Ah, Thanks Taylor, got it. I'll post a pic and update once its done

[TheLoneRoger]

Hi,
I've recently started re-building some old projects I started back in the '80's, which includes an E & MM Spectrum synth (x2!) and a couple of original Phonosonics boxes, one of which is the 'Guitar Effects Pedal' (go to love PE's understated project names!) a.k.a. Gristleizer.

Anyway, I was delighted to find this thread, but after reading the first 4 pages, my eyes are getting sore, so I was wondering if there is anywhere a summing up of the the various essential mods so I can bring mine up to date without having to plough through another 12 pages?

Also, has anyone adapted one for 15V rails? I'll be using mine with my Digisound/Spectrum modular, which  uses +/- 15V supplies.
Cheers

[disorder]

Just built mine up, sounds great but I'm having trouble with the square wave setting on the rotary switch. I don't get any modulation on that switch setting. My triangle wave looks good on a scope as does the ramp up and ramp down, I can hear those as well. But square wave is not getting to the wiper of the depth pot. The weird thing is if I probe on lug 3 of the depth pot and set the depth pot to minimum, I can see the square wave. As I slow increase depth the square wave disappears from lug 3. The square wave is sensitive to impedance to ground. What could cause this? Any suggestions? Thanks!

[disorder]

SOLVED: Theres an optional 10uF cap spot on the pcb you can populate to help reduce "ticking". Its not on the schematic but it's from the DEPTH pot wiper to ground. My guess is during the fast transients of the square wave the opamp has a hardtime keeping up with the charge requirement. Not sure. I was seeing another issue that was caused by the optional de-tick cap as well. The rampup wave would almost double in amplitude when depth pot was set to max. My guess is that with the wiper connected to lug 3 there is no longer an series resistance between that optional 10uF cap and the waveform/oscillator circuitry making it act funky. Again... cap is asking for too much current too fast or something.

Just keep that in mind...