MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

Two Thousand Six Hundred (TTSH) Ver.1 General build thread
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3 ... 115, 116, 117 [all]
Author Two Thousand Six Hundred (TTSH) Ver.1 General build thread
fuzzbass
Cablebasher wrote:
Thanks for replies dudes.

I have tried various grounds including directly off the power header and all cause silence.

I must have damaged the shield in some way.

But the cable, even without grounding the shield, has fixed the bleed so I'm going to leave it.

If it's not broke, don't fix it.

Now I just need to fix the speaker hum and work out the VCA exponentional gain and I'm finally there. After 4 years!

I think I might be the only person who finished his arp 1601 before his 2600!

There is a long history of builders thinking that the exponential cv input on the VCA is borked. But if the problem is that it distorts over 75% on the slider, relax. It's a feature not a bug.
biggiesmalls
biggiesmalls wrote:
elmegil wrote:
biggiesmalls wrote:
Hey guys, need some assistance;

First is the filter; it was working fine, i was able to sweep frequencies, all faders raised and VCA out worked fine. Then something went in the filter, i thought it was the 3958, i replaced this, still no dice. I get no signal from there at all, no sound, just empty path. How do i go about debugging this from here? Ive tested power is coming into the section fine, i seem to have readings at the legs of the 3958, between 14.97vdc and 3-7 depending which leg you're on.

I do have a scope, should i track back each transistor to see where my signal stops producing? Please fling suggestions my way.





Basically yeah, though I'd start at the entry to the section and track forward until you lose the signal.

VCF1 on the schematic is the audio input, VCF5 is the output, VCF3, VCF9, VCF11 are various points of CV control.

I'd set it up so one of the oscillators was the only input up, open the coarse slider all the way, resonance all the way down, and then start tracing.


so i tested this using the schematics as a help, what i can see is;

at each 100k fader, i can see the respective waveforms, when i track to the 220ohm resistor i dont see anything, then i try at Q1, again, dont see anything. i replaced Q1+Q2, again, dont see anything.


So theres good news and bad news, ill start with

The bad:

Had a friend help me out and we cleaned up a few joints and replaced Q1 + Q2 on the VCF, powered on, adjusted the gain/offset trimmers and boom, we had VCF working again.. I took it back home with the notion of testing each section again to see what i needed to work on to complete the synth. I was playing with it for about 20 minutes or so and was testing the filter cutoff/resonance, this is where i lost signal to the VCF again.. I had the cutoff quite low and swept the resonance down from high to low when the signal cut and im back to where i was before.

The Good:

From what i can denote, something on the cutoff + resonance circuit is potentially my issue here.. Is this common? Whats the best way to debug at this point that ive honed in on? Is the resonance drawing too much and causing a component to blow ?
danielanez
Hello All,
Maybe this is my first post in this forum, even though I've spend (on and off) the past year building a TTSH Rev.1 from the B-stock released last summer.

I finally finished the last details yesterday: made the speakers work and the reverb.

I played for about 40 minutes, and at some point, the whole thing turned off. It didn't turn on again.

I unplugged all the sections and checked my power: -15v and +15 worked perfectly.

I started plugging my sections, one by one, and they all worked fine, until I connected the noise section. If the noise section is connected, then the whole synth doesn't turn on, except the speakers give a thump, constantly, every second or so.

What could had happened? Could it have happened that because I hadn't yet calibrated much, I overloaded something?

In the noise section I did the repair No.1 suggested by the DSL-man, which is replace one transistor by a BC337-16, although I didn't put the resistor in parallel with the neighboring capacitor because (there is contradictory information about whether to put it or not, and I decided not).

Anyhow, any clues will be welcome.

very frustrating
LED-man
Please try this:
Maybe a short from a snipped resistor leg on the pcb ?
Sometimes these hide under a ic socket or other parts.
Please swap the LM301 in case they are faulty.
Check the pinout of your BC337 too.
Or a wrong resistor value which heated til he gave up.
elmegil
Seems unlikely to have been because of lack of calibration.

If you have the power off, and you measure between the rails and ground, and between the rails themselves, for that section (i.e. at the header that you plug the power for the noise section into) do you have a short? If you measure resistances in the same places, is there any resistance that's ridiculously low?

Have you confirmed that the alternate noise transistor is in correctly? You have to have one leg crossed over and take care not to short that leg to the others (I always slip a little piece of shrink wrap over the crossed-over leg).

I've finally gotten off my duff and started back up on building my last rev.1 myself, and I'm about 1/3 of the way through populating the board.....
danielanez
LED-man wrote:
Please try this:
Maybe a short from a snipped resistor leg on the pcb ?


Yes, this was it! Thanks a lot for your help. A resistor leg was touching the border of one of the sliders. TTSH is back to complete life!

Now I started calibrating. Noticed I had swapped the 250 and the 250k Trimmers on the Ring Mod and Filter sections. I guess it happened because the build doc skipped the Ring Mod and I must have missed a bit of info. Noticed because the Ring Mod Gain Trimmer didn't make much of a difference, while the V/Oct trimmer on the filter was impossible to adjust, it making a huge jump in register when trying to adjust it.

Wanted to ask: how many of you don't install the speakers? They're a little bit noisy in my case, and make noise even when they are not being used. I much rather have complete silence.

Also: how noisy is the reverb? I unfortunately didn't wire the shielded cable directly to the PCB: i soldered the shielded cable to a three-pin header, like the ones used for the power. There's a little noise, and I wonder whether it's worth the effort to unsolder the pins and solder the wire directly to the PCB. Any other ideas to have the minimum amount of noise for the reverb that anyone has used?

Thanks a lot!
elmegil
Reverb is definitely noisy in general. Did you use the modified reverb uptake circuit using the NE5534 (from memory, I reserve the right to have identified the chip wrong ;-) )?
danielanez
No, I didn't use the Driver Mod described at the DSL-man page.

https://www.dsl-man.de/display/TTSH/TTSH+Reverb+Driver+Mod

But might, actually, it looks like a simple one. Did you do it? Do you have pictures?
elmegil
I've done it several times.

It looks a little different built that way from the start than it does when you go back and re-wire it. I don't have any handy photos of the latter. But this is what my current rev 1 build looks like:

(ignore the dust, it's been under my desk a while now waiting for me to do all the calibration smile )

fuzzbass
elmegil wrote:
Reverb is definitely noisy in general. Did you use the modified reverb uptake circuit using the NE5534 (from memory, I reserve the right to have identified the chip wrong ;-) )?


I did this mod on my V1 and it didn't buy me much. Look first at the cabling you use. Antenna wire such as RG174 is good for this. Gold plated Monster cables are crap. Also some noise is to be expected with spring reverb.
sduck
You might be able to clean up the reverb noise quite a bit by moving the tank around, and/or rerouting the cables. Depends on the case, and how you're powering it, and the environment you have the TTSH in for normal use. I had one that was slightly noisy, but cleaned right up when I flipped the tank over so the inlets were pointed the other direction. Also, get your tank cables as far away from power lines as you can.
fuzzbass
sduck wrote:
You might be able to clean up the reverb noise quite a bit by moving the tank around, and/or rerouting the cables. Depends on the case, and how you're powering it, and the environment you have the TTSH in for normal use. I had one that was slightly noisy, but cleaned right up when I flipped the tank over so the inlets were pointed the other direction. Also, get your tank cables as far away from power lines as you can.


The wire you are most concerned with here is the return line. Keep it short, and away from the PCB, esp. power supply and the noise gen and internal clock areas. The typical duplex RCA audio cables (as one would use to hook up a tape deck) do not have sufficient screening. Coaxial wire engineered for radio frequency detection performs better. If you look in the back of old Fender reverb type amps, you will see antenna wire running to the reverb unit.

I use standoffs to dress these wires up, and away from the main board. I build my own hookups using RG174 and Switchcraft 3501MX plugs.

Warning: do not connect or disconnect the reverb wires while under power. The return amp has very high gain, and little transients coming from the input will smoke the LM301 instantly.
Cablebasher
Hey guys

So I have had my TTSH Rev 1 complete a few years now.

There have been a few things that have bothered me but not enough to open her up again.

Some I have realised are as design (exp vca level) but some I think are genuine (minor) issues and wanted to check if others had experienced them.

I realise most people finished their Rev1s 5 years ago and have properly forgot the build but here goes:

1. Clock speed changes pitch of filter in self resonance mode (very slightly) This is fixed by turning the clock speed up very high but would be nice to fix

The VCOs are not affected by the clock speed.

Note I did not do the clock fix as it didn’t effect the VCOs. Maybe I should.

2. The Manual start button gives my ADSR and AR 9.7V sustain at full level.

My gate from keyboard gives my ADSR 9.7V sustain (same as manual start) but my AR only 8.2V.

Looking at the schematic the only thing in the AR between the gate input and the manual start is a doide. So I’m guessing it’s the wrong way round.

Anyone else experienced this?

(3). Final and most annoying.

With my filter fully open, if I add any modulation, for example a full sustain ADSR, it lowers the volume of the filter output. If I have the modulation level at full and ADSR sustain at full I get a lot of volume loss.

Note there is no effect on the filter frequency, Just the volume.

Any ideas?

That’s it.

Thanks as always.
elmegil
Cablebasher wrote:

Looking at the schematic the only thing in the AR between the gate input and the manual start is a doide. So I’m guessing it’s the wrong way round.


Sounds more like diode drop. Maybe replace it with a schottky or other type of diode that has a lower than typical drop?

A standard 1N4148, which is what was spec'd in the TTSH, has about a 1V drop at 10mA. No idea off the top of my head whether this is pulling more or less than that, but it's in the right order of magnitude to be your problem.
fuzzbass
Cablebasher wrote:
Hey guys

So I have had my TTSH Rev 1 complete a few years now.

There have been a few things that have bothered me but not enough to open her up again.

Some I have realised are as design (exp vca level) but some I think are genuine (minor) issues and wanted to check if others had experienced them.



The design is there for a reason. You can overdrive the exponential control input to add sharp, distorted transients to the attack phase. This is what the old pros do with their 2600s. It is used with brass type patches.

Cablebasher wrote:



1. Clock speed changes pitch of filter in self resonance mode (very slightly) This is fixed by turning the clock speed up very high but would be nice to fix

The VCOs are not affected by the clock speed.

Note I did not do the clock fix as it didn’t effect the VCOs. Maybe I should.



There was more than one fix to this if I recall. On my V1 TTSH, I defeated the flashing clock indication, its on solid now. I don't recall the particulars but might just involve removing the transistor, shorting its emitter and collector pads and adjusting the 680r resistor to some higher value to match the intensity of the other LEDs. Another alternative is to trim the base frequency of the internal clock down so that at minimum setting, the clock latches up and stops.

Cablebasher wrote:


2. The Manual start button gives my ADSR and AR 9.7V sustain at full level.

My gate from keyboard gives my ADSR 9.7V sustain (same as manual start) but my AR only 8.2V.

Looking at the schematic the only thing in the AR between the gate input and the manual start is a doide. So I’m guessing it’s the wrong way round.

Anyone else experienced this?



If a diode was wrong, you would probably have worse problems. What you describe is similar to several cases I have looked at where a gate measures correct voltage, but sags under load. Try putting your gate through some type of buffer first. (note if you have a gate booster installed, it has the buffer already).

Cablebasher wrote:


(3). Final and most annoying.

With my filter fully open, if I add any modulation, for example a full sustain ADSR, it lowers the volume of the filter output. If I have the modulation level at full and ADSR sustain at full I get a lot of volume loss.

Note there is no effect on the filter frequency, Just the volume.



Is resonance turned up when you made this observation? If yes, consider: just because you don't hear the filter frequency increasing, does not mean it is not happening. It might be happening up in a register you can't hear and/or your monitoring system can't track. The VCOs and the VCF respond well beyond 20Khz. If a resonance peak is shifting up into frequencies you can't hear, it is doing so by taking energy from lower frequencies you can hear. This is sometimes referred to as the bass penalty of resonance.
Cablebasher
Thanks Elmegil and Fuzzbass for the quick response.

Envelope issue:

Ill try buffering my gate before it hits the AR. If that doesn't help I will replace the Diode.

I have a gate booster but never installed it as my kenton pro 1 outputs a 11V gate and separate trigger that (i thought) was doing the trick.

Clock bleed:

I will do the fix on LED Mans website (remove tranny and jumper pins) and see if that helps.

Filter volume drop:

The resonance is fully down (No resonance) so its not normal ladder filter volume drop with increased resonance.

With the filter down, positive modulation does as it should, opens the filter. But with the filter fully open, adding positive modulation just lowers the volume.

I checked it on a scope and a sawtooth going in keeps its shape but just get attenuated with positive voltage.

It would be interesting to see if this is exclusive to me.

If someone with a Rev 1 could open the filter fully (including fine tune) and then turn the ADSR mod slider up fully and play a note with a full sustain ADSR and see what happens?

Obviously i wouldn't add positive modulation to a fully open filter (why bother) but in a live situation when playing with the filter cutoff and filter envelope it does become a pain.

Thanks!
fuzzbass
Cablebasher wrote:

Filter volume drop:

The resonance is fully down (No resonance) so its not normal ladder filter volume drop with increased resonance.

With the filter down, positive modulation does as it should, opens the filter. But with the filter fully open, adding positive modulation just lowers the volume.

I checked it on a scope and a sawtooth going in keeps its shape but just get attenuated with positive voltage.

It would be interesting to see if this is exclusive to me.

If someone with a Rev 1 could open the filter fully (including fine tune) and then turn the ADSR mod slider up fully and play a note with a full sustain ADSR and see what happens?

Obviously i wouldn't add positive modulation to a fully open filter (why bother) but in a live situation when playing with the filter cutoff and filter envelope it does become a pain.

Thanks!


I didn't realize before, but I am accustomed to the filter behavior you describe.

I looked at this on both my old V1 TTSH and a V2 as well. I confirmed your findings on both. The gain of the 4012 VCF output drops when the frequency set point rises above ~15Khz with resonance zeroed. Looks like a feature, not a bug in your build. My guess is this comes from the slew rate limitations of the LM301.

The range of the VCF set frequency is very wide. I calibrate VCF on my builds to 130.8hz at 0.00V, and when I sweep the control up to max, it hits about 75khz! I don't think you can trim this behaviour out of your VCF, but you can move the set frequency at 0.00V lower if you like, which would move the trouble spot to the right on the Frequency control. Or, you can just keep the Frequency control and modulation amount down to preserve the gain you want. My old ears can't hear much above 15K so I am in the habit of raising the VCF frequency to about 60% to "open" the filter. As soon as I started taking measurements on my V1 TTSH, I remembered all this.

Generally in practice (and this is true for all analog synths) you must reduce the VCF set frequency as you raise envelope modulation.

Suggestion: Recalibrate your VCF to 8.175hz at 0.00V (Freq left, and Fine centered). After you do this will probably have to adjust all three other trimmers (1V/Oct, Offset and Gain). Use a square wave from VCO1 to calibrate gain and offset, with res zeroed. (don't calibrate gain or offset using the res-generated sine). This will move the sweet spot on the Frequency control more toward the center, and with Frequency maxed and ADSR modulation maxed, the affect on gain, while still there, is not quite so drastic. If you then bring the Freqency control down to about 75%, there is almost no loss of gain from full ADSR modulation.

This is, however, totally subject to taste, and I recommend you do this with a scope and frequency counter connected to the output of the VCF, and while using headphones, and a 49 keyboard source generating between 0.00 and 4.00V
Cablebasher
Hey Fuzz

Thanks for looking into it for me

Good to hear it’s a feature and not an issue

I think I may do your suggested mod. At the moment I do find, with the filter trimmed as per the manual, that the filter closes very quickly on the slider. To my ears at least.

Your mod might give me a bit more scope on the slider and fix my “positive modulation volume drop”’issue.

I think I will soon run out of issues to solve with my TTSH.
Vast_Halo
I own a V1 TTSH that was assembled for me by an EE and that has worked perfectly until now. I control it from my PC using Silent Way. Yesterday - literally mid-session - all three oscillators abruptly stopped tracking correctly. My sequences, which are entirely equal-tempered, suddenly developed a woozy, micro-tonal quality, so something somewhere along the line has evidently started skewing the conversion of the MIDI notes being sent from my DAW.
To check whether there was a problem with the Keyboard CV bus, I sent the CV output from Silent Way directly into each of the oscillators in turn, and they all still sounded wrong. I then tried re-calibrating Silent Way against the TTSH. It didn't help at all, and the scaling graph it generated - which was originally a nice, straight 45 degree slope - now has a cliff-face drop-off for the bottom octave. (Not that the same notes transposed to the upper octaves sound any better.)
I also tried using different outputs from my DAC (a MOTU 828 Mk.II), in case a channel opamp had failed or something, but to no avail.
Would anyone have any thoughts on where the problem may lie? I’m aware that there are calibration screws accessible from the TTSH’s front panel, but I’m loath to start fiddling with them unless I’m sure that it will actually help.
Jaytee
I had similar symptoms in my rev3 when the DC/DC converter running my negative rail failed (though I don’t want to suggest this is the only possible cause). Do you know what kind of power circuit is installed in your TTSH?
Vast_Halo
Many thanks for your reply, Jaytee. You may well be on to something there. As I recall, I bought a TDK-Lambda part for the DC-DC conversion. I remember it was one of the more expensive options!
If it needs replacing, would you have a recommendation for a current-day equivalent?
LED-man
Vast_Halo wrote:
I own a V1 TTSH that was assembled for me by an EE and that has worked perfectly until now. I control it from my PC using Silent Way. Yesterday - literally mid-session - all three oscillators abruptly stopped tracking correctly. My sequences, which are entirely equal-tempered, suddenly developed a woozy, micro-tonal quality, so something somewhere along the line has evidently started skewing the conversion of the MIDI notes being sent from my DAW.
To check whether there was a problem with the Keyboard CV bus, I sent the CV output from Silent Way directly into each of the oscillators in turn, and they all still sounded wrong. I then tried re-calibrating Silent Way against the TTSH. It didn't help at all, and the scaling graph it generated - which was originally a nice, straight 45 degree slope - now has a cliff-face drop-off for the bottom octave. (Not that the same notes transposed to the upper octaves sound any better.)
I also tried using different outputs from my DAC (a MOTU 828 Mk.II), in case a channel opamp had failed or something, but to no avail.
Would anyone have any thoughts on where the problem may lie? I’m aware that there are calibration screws accessible from the TTSH’s front panel, but I’m loath to start fiddling with them unless I’m sure that it will actually help.


Works the TTSh without CV ?
Measure the voltage at one opamp -15/15v (Check the datasheet for the pinout)
I don’t think the failure is from the powersupply, maybe a defect opamp.
Because, in case of a failure of the psu the other functions are affected too (VCF, VcA..)
Jaytee
LED-man wrote:
Works the TTSh without CV ?
Measure the voltage at one opamp -15/15v (Check the datasheet for the pinout)
I don’t think the failure is from the powersupply, maybe a defect opamp.
Because, in case of a failure of the psu the other functions are affected too (VCF, VcA..)


When my DC/DC converter failed, I’m sure stuff like the VCA/VCF were affected, but not nearly in such an obviously audible way as the VCO. FWIW, the failure mode was not what I expected. It didn’t go completely dead; instead it drooped down from -15V to about -14V and became unstable (wobbling by 1-200mV in either direction). The result was what the fella above described—sudden wobbly VCOs while everything else seemed to work correctly.

Not saying you’re wrong—like I said, this is far from the only possible cause for these symptoms—just clarifying what I experienced. Easy enough to check the rails for stability if one has a multimeter handy.
Vast_Halo
Guys, sorry for wasting your time with this. There's nothing wrong with my TTSH. The notes sounded weird because I had inadvertently attenuated the CV output from Silent Way. d'oh!
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3 ... 115, 116, 117 [all]
Page 117 of 117
Powered by phpBB © phpBB Group