TTSH Ver.3 (rev.8) General build thread

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Jaytee
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Post by Jaytee » Mon Apr 29, 2019 10:06 pm

The reverb can also pick up interference from other stuff that’s plugged in in the room. I found that if I turn off my IKEA LED build lamp, suddenly my Reverb becomes usably quiet.

My filter has a very faint “shhhhhh” but it’s quiet enough that I never even noticed it until someone else pointed it out and I checked to listen if it was on my own TTSH. If it’s loud enough to bug you, it might be an actual issue. If you trace down the source of it, I’d be curious to hear about it!

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Post by the bad producer » Tue Apr 30, 2019 4:13 am

FactoryDefault wrote:
the bad producer wrote:I have a TTSH here (which I didn't build) that is really noisy
My reverb still picks up psu noise despite cable shielding/moving the reverb tank/changing tank grounding/steel barriers/voodoo rituals so I keep it at max 50% if I use it. I have been researching the install of a power-one psu but I read the other day that it can potentially induce hum so it seems there is not a perfect solution. Don’t which I prefer - hum or whine! :hmm:

The vcf issue does not sound normal. Did you get both filters with the TTSH? Can you post a sound sample?
Thanks for the info, I did try a Power One and it was a lot lot worse, also tried an Analogue Solutions PSU and another one I had lying around, again pretty bad (this is in the stock metal case)...

I only have the built unit, so no choices on VCF. I'll try and grab a sample later.

And thanks Jaytee, I'll check out my other things in the room! Be good to not have to do that as it's not staying here much longer, would really like to get rid of it!

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Post by fuzzbass » Tue Apr 30, 2019 7:45 am

the bad producer wrote:
FactoryDefault wrote:
the bad producer wrote:I have a TTSH here (which I didn't build) that is really noisy
My reverb still picks up psu noise despite cable shielding/moving the reverb tank/changing tank grounding/steel barriers/voodoo rituals so I keep it at max 50% if I use it. I have been researching the install of a power-one psu but I read the other day that it can potentially induce hum so it seems there is not a perfect solution. Don’t which I prefer - hum or whine! :hmm:

The vcf issue does not sound normal. Did you get both filters with the TTSH? Can you post a sound sample?
Thanks for the info, I did try a Power One and it was a lot lot worse, also tried an Analogue Solutions PSU and another one I had lying around, again pretty bad (this is in the stock metal case)...

I only have the built unit, so no choices on VCF. I'll try and grab a sample later.

And thanks Jaytee, I'll check out my other things in the room! Be good to not have to do that as it's not staying here much longer, would really like to get rid of it!
I just finished building TTSH numbers eleven and twelve for my shop. I have built all versions, using all types of PSUs. I don't know what the cause of your reverb noise is, but it is probably a combination of factors. You are aiming for good enough. No spring reverb will ever be perfectly noise free.

Here are some suggestions:

The Rev8/V3 offboard PSU with Murata DC-DC converters can be a source of high pitched noise bleed. There are things you can do to minimize the effect. 1. The external DC brick should be rated at least 2A. If you use a lesser brick, the switching function in the Muratas has to work harder, with greater noise field developing around them. I recommend this brick: Meanwell GST25A12-P1J (you will need to also provide location specific AC cable). Some bricks have a 0V side that is isolated from earth - the one above does not. These can make noise worse because they don't shunt all the noise your shielding picks up. You will know this to be the case if you connect a patch cable to something outside the synth and the noise goes way down. 2. You can shield the Muratas to shunt some of the noise away, using copper foil tape. The tape should be connected to a 0V point on the PSU board. It should go around the PSU sub board front and back. In the photo below, you don't see the underside, but the 0V jumper is there, and there are cutouts around the solder points for the Muratas. I also add a top coat of metal protector to the foil, to prevent the otherwise eventual oxidation and disintegration of the copper (the product I use is called Everbrite). 3. The return line from you reverb spring unit is where the noise is picked up. The line should be kept to minimum length, dressed away from noise sources (PSU, Noise Generator, Internal Clock), and constructed from antenna grade cable. The dual RCA cables you find retail are made from audio grade cable - even those sold specifically for connecting reverb units! I use RG174 cable, and cut/terminate the reverb cables to exact length.

There are many good reasons for using a linear AC power supply for the TTSH, but minimizing reverb noise is not one of them. With a linear supply, you are just exchanging one high-pitched source of reverb noise with a lower -pitched noise source. The very best reverb noise performance of any build here was in a V3 TTSH with stock PSU (Muratas), incorporating all the suggestions above.

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Post by FactoryDefault » Tue Apr 30, 2019 8:29 am

Awesome write-up fuzzbass. Is your copper tape ielectrically connected to or insulated from the cases of the Muratas? I have copper tape on mine and I tried grounding the tape at one point but I realized as I was doing it that the Murata cases had a positive DC voltage. (At least relative to the ground point I chose - don’t remember where - it’s been a while)

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Post by the bad producer » Tue Apr 30, 2019 2:18 pm

Thanks fuzzbass, great info there!

I tried a couple of 15V and a (IIRC) 20V PSU - all were around 4A output, and the 15V were the ones with GND not isolated.

I'll try the tape out - I've found some locally, does the example you posted have the tape over a cardboard structure, or is the tape enough on it's own? Sorry never used it before!

I'll also check the reverb cables, the ones supplied do look crap.

:tu:

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Post by fuzzbass » Tue Apr 30, 2019 3:04 pm

FactoryDefault wrote:Awesome write-up fuzzbass. Is your copper tape ielectrically connected to or insulated from the cases of the Muratas? I have copper tape on mine and I tried grounding the tape at one point but I realized as I was doing it that the Murata cases had a positive DC voltage. (At least relative to the ground point I chose - don’t remember where - it’s been a while)
The tape I use is copper foil with pressure sensitive adhesive directly on the copper. I don't believe the cases on the Muratas are internally connected, or have any voltage on them. It would probably be an improvement if they did have a connection to 0V - then the foil would have no benefit.

One other thing... if the effect you want is to swamp the sound in reverberation by driving the reverb sliders up to 75-80%, you are going to get noise no matter what. Nature of the beast. The signal coming off the return transducer is very weak, down near the noise floor. If you bring this up to a level where it competes with the audio signal level, you will bring the noise floor up too.
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Post by the bad producer » Sat May 04, 2019 9:40 am

Affected your additional recommendations today, fuzzbass (copper tape, better reverb cables) and the difference is night and day!

I owe you a beer :guinness: :hyper:

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Post by fuzzbass » Mon May 06, 2019 1:03 pm

the bad producer wrote:Affected your additional recommendations today, fuzzbass (copper tape, better reverb cables) and the difference is night and day!

I owe you a beer :guinness: :hyper:
:guinness:
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Post by fomtoberheim » Wed Jun 19, 2019 8:35 pm

Really stuck here and super excited to get this ttsh up and running.
This is the waveform I get for every test point on the sample and hold.

I checked all the components. Somethings not working right. If I’m not getting a waveform, does anyone know what components I should start going through and testing?

Thanks in advance!


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Post by nologin » Thu Jun 20, 2019 8:25 am

Hi,
There is one question that i had never asked myself, except the transistors that must be paired. The gain of transistors PNP and NPN, are there recommendations? knowing that i had not used the bom mouser. I have 2N3904H badged NPN and 2N3906B badged PNP. :hmm:

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Post by fuzzbass » Fri Jun 21, 2019 4:30 am

fomtoberheim wrote:Really stuck here and super excited to get this ttsh up and running.
This is the waveform I get for every test point on the sample and hold.

I checked all the components. Somethings not working right. If I’m not getting a waveform, does anyone know what components I should start going through and testing?

Thanks in advance!

Looks like your clock is inop, and what you see on your scope is just some stray signal that is bleeding in (2.25Khz, 200mv). Maybe a nearby florescent light...

In your photo, the clock occupies the bottom edge and bottom left quadrant. The two BC558s and the 2N4870 are the core of a simple sawtooth oscillator. You should see the saw on the right end of the 47K resistor as indicated on the board. Check all resistors by color band, verify all diode orientations and reflow everything here. If still no oscillations, with most likely culprit is the 2N4870 JFET. Then, move on to the BC558s. You should be seeing a pulse wave at pin six of the op amp (the one on the left in your photo). Higher up there is a test point indicated where a 22K and 10K resistor sit next to each other. This is clock input to the electronic switch, and you should see very brief ~1ms trigger here. On my analog scope they are difficult to see unless the beam intensity is cranked up. The init rate trimmer looks like it may have taken some heat damage.
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Post by aberg » Sun Jul 28, 2019 10:50 am

Hi All!

Calling forth the forum gods


I just powered up the board to find myself with a head scratcher.
The LEDs flash on at full power then fade to about 20% after 1 second, no response from the LED trimmer.

Secondly, I seem to only be getting output from the vco1 and ring mod/voc1. The vco2, vco3 and vcf are unresponsive.

Any thoughts or insight would be greatly appreciated!

:hail: :hail: :despair:

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Post by fuzzbass » Sun Jul 28, 2019 11:50 am

aberg wrote:Hi All!

Calling forth the forum gods


I just powered up the board to find myself with a head scratcher.
The LEDs flash on at full power then fade to about 20% after 1 second, no response from the LED trimmer.

Secondly, I seem to only be getting output from the vco1 and ring mod/voc1. The vco2, vco3 and vcf are unresponsive.

Any thoughts or insight would be greatly appreciated!

:hail: :hail: :despair:
What do you measure on all four power rails?
Have you run through calibration for the VCOs or Filter yet? The filter has a gain trimmer and if that is zeroed, a working filter will have no output. It also has a base frequency trimmer and if that is zeroed, the filter will filter everything.

Move your VCO cores around and see if the VCO fault follows the cores.
Get your PSU, VCOs, Filter, and VCA working first. Then move on to the other bits. The VCA slider at top effectively bypasses the need of a CV to open the VCA, so you can ignore the AD and ADSR for now. Helps if you have use of a scope...
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Post by Jaytee » Sun Jul 28, 2019 4:37 pm

Did you build the faulty LED delay circuit? Usually it turns the LEDs off entirely instead of simply dimming them, but otherwise the symptoms fit. There’s an opamp that is supposed to be replaced with a jumper.

Never hurts to take some high-resolution, well-lit photos of the problem areas!

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Post by Haloweak » Tue Sep 10, 2019 1:08 pm

Hi everyone!

I just finished my TTSH V3 build and all functions are fine except my speaker. I use two Peerless speakers on my ttsh, when I push my speaker to the max volume, its sounds like add a short envelop to my VCO's pitch, but it's normal when I lower down my speaker. Also I can hear my VCOs are bleeding when I raised up the VCF fader. Is that normal to TTSH?

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Post by Jaytee » Tue Sep 10, 2019 1:26 pm

The peerless speakers are not a good impedance match for the TTSH. When you crank them, they max out and can cause all kinds of weirdness. The general suggestion is simply not to crank them. Alternatively, Jameco sells some very cheap 45ohm speakers that match the TTSH footprint and are a much better match for the power amps (designed for the 2600’s 40ohm speakers).

The VCO bleed...is that when the speakers are cranked, or all the time? I’ve never gotten VCO bleed in the filter, though I get a small amount of noise bleed (as do a couple other folks at least).

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Post by Haloweak » Tue Sep 10, 2019 1:33 pm

Hi Jaytee, thanks for your help!

Yes my VCOs bleed all the time, even when I connect my ttsh into my audio interface, I can still hear the bleeds on my monitor.

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Post by Jaytee » Tue Sep 10, 2019 1:54 pm

Any mods installed? The sync mod seems like it might cause something like that.

And it’s a rev 3, yes?

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Post by Haloweak » Tue Sep 10, 2019 2:40 pm

Jaytee wrote:Any mods installed? The sync mod seems like it might cause something like that.

And it’s a rev 3, yes?
Yes it's rev3 only with gate booster, and I tested a little bit with proper gain of my audio interface, it's works fine, only some white noise. But for the speakers and headphone jack on my ttsh , all of those noise like vcos bleeds, reverb noise, clock leds blinking sounds are coming out...I think the best solution is not use those speakers lol

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Post by Jaytee » Tue Sep 10, 2019 5:38 pm

Maybe check your wiring? Plenty of people have used those speakers without bleed.

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Post by sduck » Tue Sep 10, 2019 8:22 pm

Have you calibrated it yet? That tends to sort out a lot of little problems like this.
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Post by Haloweak » Wed Sep 11, 2019 2:16 pm

sduck wrote:Have you calibrated it yet? That tends to sort out a lot of little problems like this.
Hi sduck,

Yes I've already calibrated my ttsh, and I found that when I turned my OUTPUT OFFSET trimmer counter clockwise bleeds are disappeared, maybe there is something wrong with my calibration, I'll try to re-calibrate it again.

Also I just notice that my s&h output has some weird problem, it can't hold the signal, the s&h signal looks like a sawtooth wave on my oscilloscope that always drop. Is that a bad 2n3958 cause this problem?

It looks like this on my oscilloscope
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Post by fuzzbass » Wed Sep 11, 2019 3:57 pm

Haloweak wrote:
sduck wrote:Have you calibrated it yet? That tends to sort out a lot of little problems like this.
Hi sduck,

Yes I've already calibrated my ttsh, and I found that when I turned my OUTPUT OFFSET trimmer counter clockwise bleeds are disappeared, maybe there is something wrong with my calibration, I'll try to re-calibrate it again.

Also I just notice that my s&h output has some weird problem, it can't hold the signal, the s&h signal looks like a sawtooth wave on my oscilloscope that always drop. Is that a bad 2n3958 cause this problem?

It looks like this on my oscilloscope
What signal are we looking at here? It looks to me like VCO-Saw and Noise mixed in the filter's audio inputs. If you have those inputs raised in the VCF, you can expect the scope to show that.

The S&H puts out CV, it's output won't look like this unless something very unusual is wrong. Now, if what you mean is that the sampled/held CV is drooping, and not being held, that is a common issue and usually a leaky 2N4392 jfet (Q4 not pinching off completely between cycles and thus allowing C8 to discharge via CR6 and R12).

If you are hearing VCOs when you are not playing notes, and the base level control at the top of the VCA is minimized, chances are your VCA needs calibration.
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Post by Haloweak » Wed Sep 11, 2019 4:22 pm

fuzzbass wrote:
Haloweak wrote:
sduck wrote:Have you calibrated it yet? That tends to sort out a lot of little problems like this.
Hi sduck,

Yes I've already calibrated my ttsh, and I found that when I turned my OUTPUT OFFSET trimmer counter clockwise bleeds are disappeared, maybe there is something wrong with my calibration, I'll try to re-calibrate it again.

Also I just notice that my s&h output has some weird problem, it can't hold the signal, the s&h signal looks like a sawtooth wave on my oscilloscope that always drop. Is that a bad 2n3958 cause this problem?

It looks like this on my oscilloscope
What signal are we looking at here? It looks to me like VCO-Saw and Noise mixed in the filter's audio inputs. If you have those inputs raised in the VCF, you can expect the scope to show that.

The S&H puts out CV, it's output won't look like this unless something very unusual is wrong. Now, if what you mean is that the sampled/held CV is drooping, and not being held, that is a common issue and usually a leaky 2N4392 jfet (Q4 not pinching off completely between cycles and thus allowing C8 to discharge via CR6 and R12).

If you are hearing VCOs when you are not playing notes, and the base level control at the top of the VCA is minimized, chances are your VCA needs calibration.
Hi fuzzbass, really appreciate for you help!

The picture is my sample and hold signal ,I've searched in REV1 thread and found the problem is my 2N4392, I've already order some new jfets hope it will fix my problem!

After testing my ttsh I found that there's so many problems with my can jfets like vco2 won't gives me a nice sine wave and triangle. I think my super hot solder iron may completely distory some of my jfets.

I still have some problems with my reverb hum and when I connect a cable or use probe touch the ground on pcb, the hum disappered. I found some thread about it but I'm really confusing about how to solve this problem...I'm using a murata DC/DC convertor with a Meanwell 24v 2.5A powerbrick.

Sorry for these stupid questions and really thank you gus for helping me!

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Post by FactoryDefault » Wed Sep 11, 2019 6:02 pm

Haloweak wrote:I think my super hot solder iron may completely distory some of my jfets.
Not sure if there is any research to support this but you can buy heat sinks to help protect your jfets or any other rare and delicate components from heat.

They look like small copper alligator clips and you attach one to each leg of the component. It’s a few bucks for a set of 5 on amazon.

A temp controlled iron probably helps too though - you really only want the tip to be a few degrees above the melting point of your solder.

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