Two Thousand Six Hundred (TTSH) Ver.1 General build thread

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ultravox
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Post by ultravox »

Excellent work Nordcore. And you say with your regulator board we can also keep the blinky clock LED?
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Nordcore
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Post by Nordcore »

Yes. No additional anti LED blink/clock bleed changes needed.

Albeit I recommend adding a resistor to the base of the 2N5127 (for different reasons).

The good thing about this solution with the extra regulator for the VCO is, that it leaves your supply usable for add-ons.
Even the small (15W) converter has some power left, good enough for a (simple) midi interface. The large (30W) converter might even supply the amp, so you can keep full input voltage range and galvanic isolation from the converter. (I've tested the amp (LM1875) on the small one, does work, but of course it blinks out, when you crank up the volume... )
Altitude909 wrote:So which part did you settle on?
On the negative side I kept the LM2991, as it works good.
On the positive side I'll try TL1963. TPS7A4501, LT1963 and LT1965 have the same pinout and could also be used.

Just saw that Reichelt has LT1963 so I might give that a try on my veroboard.
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Post by elmegil »

Nordcore wrote:You could solder the trimmers (and caps) on the other side, omit the MTA connectors and it will be just a little higher than the VCO modules. But than the trimmers must be adjusted with the module unmounted. ( ... connected by some cables ... )
Would side-trimmed versions work? With the adjustment on the side instead of the top?
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Post by elmegil »

Nordcore wrote:The large (30W) converter might even supply the amp, so you can keep full input voltage range and galvanic isolation from the converter. (I've tested the amp (LM1875) on the small one, does work, but of course it blinks out, when you crank up the volume... )
I'm not following you here.

I have the larger of the DC DC converters (or perhaps a compatible one, definitely has the same specs), and would be happy to report back results....in a couple of weeks when I get there :)
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Post by Cablebasher »

This seems like a pretty easy work around to the problem.

Easy because someone else has done all the hard work (nordcore).

I'm guessing (hoping) a PCB run will be the next stage?

It seems this TTSH is an ever evolving journey!
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Post by Nordcore »

elmegil wrote:Would side-trimmed versions work? With the adjustment on the side instead of the top?
I did not choose side trimmers first, because they are not very good to adjust, as the adjustment would be very close to the main board.

Thinking again, that is not so much of problem: as the input side has an cable anyway, you can just unplug the board, do the adjustment, and plug it in again.
A little fine tuning should be no problem with the not so well accessible trimmer slots.

So I'll rework it to have it stuffed from the other side - similar to the VCOs.

The regulators will go on top. On the bottom side you would not be able to access their soldering pads, as soon as the other components have been soldered in.

And I'll fit proper right angled MTA connectors for input, VCO3 and VoltageProcessor(option), going to the stuffed side.

That should look much nicer.
elmegil wrote:I'm not following you here.
Where did I loose you?

It was not meant to suggest running the amp with the small converter. It was just a test, as Jon had experienced problems with the amp supplied by the converter. May be that was the TDA 2030, the LM1875 does run as it should.
(Or maybe he had supplied it with +/- 15V... that would give some serious output power. Unfortunately it would require serious input power, the efficiency of such amps partially loaded is miserable. )


=========================

What about black PCBs?
Prototypes (first ten, I hope they will come out fully usable) will be green.
But on the "series" it should be not too much more (1$ or so) for black ones.
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Post by M-Circus »

qp wrote:
Nordcore wrote: There are three sources of variable current:
- the LED.
- the LM301 (A42). (Swap in a TL071, it shows this effect much less. )
- the output divider R386/R388. (Working on that)
Swapped the 301 with a 071 and it helped tremendously! It's still there, but nowhere near as audible. May look into other power options and ditch the DC-DC converter. Thanks for the advice!
For those of us that couldn't read schematics if our lives depended on it: which of the three LM301s in the noise section are we talking about here?

Edit: And yes, I'm gonna learn it. Soon...
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Post by elmegil »

Nordcore wrote:
elmegil wrote:I'm not following you here.
Where did I loose you?
Nordcore wrote:The large (30W) converter might even supply the amp, so you can keep full input voltage range and galvanic isolation from the converter.
I'm not understanding this. My understanding is that the amps are meant to be fed from before the DC DC converter, and I'm not sure how your regulator modifies that recommendation, or what you mean by "galvanic isolation from the converter".
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Post by Nordcore »

elmegil wrote:My understanding is that the amps are meant to be fed from before the DC DC converter
Yes.
My suggestion was that you might change that, as it has some drawbacks. (Narrower supply range, galvanic connection between wall wart and TTSH audio ground = possible noise problem (as with some notebooks, so not hum but "digital" noise) )


Clock-LM301, to be swapped for TL071.
(Less clock bleed if LFO-LED already bridged)
Image

another one: The LAG would also like to have a TL071. Here it kills the offset, so the LAG processor get usable for pitch.
And if you like the lag to have some more lag at maximum, increase the 100nF cap (=> 220nF). (Film cap)

Image
Last edited by Nordcore on Sun Jun 08, 2014 5:24 pm, edited 1 time in total.
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Post by M-Circus »

Thanks! And bollocks! I installed that 100n film cap this very evening... :doh:
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Post by Nordcore »

Cablebasher wrote:I'm guessing (hoping) a PCB run will be the next stage?
This side facing the TTSH-board:
Image
Most components are stuffed here.
J3 and J4 are female connectors, plugging directly in the TTSH mainboard.

The caps near the power connectors on the TTSH board should be soldered out. (They are not needed, might get into the way, and the ceramics can cause stability issues with the negative regulator. )

J1 (input from power distribution) J2, J5 are unshrouded rectangular MTA connectors. So they can be plugged from the side.

What you see when it's plugged in it's place:
Image

Only the both SMDs are soldered on top.
TP (test point) 1..3 are just pads/holes for the DMM tips, nothing soldered in.


Obey the "mixed up" [+ 0 -] for VCO1/Volt.P. that is because the rectangular MTA shows in different directions on different board sides. On the input side (showing left (towards power distribution) it has a "plain" 1:1 connection, but on the VCO 1 side + is upper. I put lots of +/- to help with that. (An yes, they are double checked. And I'll check them again.. )
Last edited by Nordcore on Mon Jun 09, 2014 5:01 am, edited 1 time in total.
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ultravox
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Post by ultravox »

So we'll be removing the 10uF and 100nF caps from all 3 VCO power connectors...correct?
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Post by Nordcore »

If they fit the "tetris" part when plugging the piggyback board in, the 10uF might be left/put in.

Only the 100nF ceramics must be removed from all three VCOs (and the Voltage processor if you're going to supply it stabilized).


Exact build instructions, schematic and BOM will follow when the prototypes are working.
The above pictures are already outdated:
Changed nominal out voltage labeling to 14.6V.
Fixed adjust circuit for negative part (240 Ohms and variable part where swapped :doh:).
Recalculated the divider resistors for nominal output, reference tolerance and the reference voltage from the data sheet matching the used device.
Swapped the /Shutdown pin on the positive regulator to Vin, so it is enabled :doh:²
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Post by M-Circus »

Nordcore wrote: Exact build instructions, schematic and BOM will follow when the prototypes are working.
Wise move. Will probably save you about 300 questions from people like yours truly... :hihi:
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TTSH Spring Reverb

Post by sirg »

Half way through my build, trying to figure out what a good spring reverb to get would be, I don't have any experience building with one. So I'd be keen to hear peoples experiences or recommendations. The bom lists these two : Belton Accutronics 1AB2A1B
BL2AB3C1B from Banzai Electronics

I'm just wondering if anyone can say if they sound any good (those who like spring reverbs) or if there's anything better?

Also wondering about if it's worth going stereo, if that might sound cool?

Thanks for your advice!
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Post by elmegil »

Talk to xpander about spring reverbs

viewtopic.php?t=104192

He has extras....
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Post by Nordcore »

Are you really up for a *good* reverb?
Than a spring reverb might not be the best selection.

The 1AB2A1B seems to be original, that's one of the crappiest tanks they have ever made.
The BL2AB3C1B is larger (17", not 9") and has "long" reverb time.

You can use a lot of different tanks.

As this is DIY there is no need to select the "proper" input and output grounding, as that can be changed with little effort.

What must fit: Input = A (8Ohms), Output = B (2kOhms). The mounting direction must fit your case.
So any Accutronics: _AB__1_ can be used.
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Post by Luap »

Nordcore wrote:Are you really up for a *good* reverb?
Than a spring reverb might not be the best selection.

The 1AB2A1B seems to be original, that's one of the crappiest tanks they have ever made.
The BL2AB3C1B is larger (17", not 9") and has "long" reverb time.

You can use a lot of different tanks.

As this is DIY there is no need to select the "proper" input and output grounding, as that can be changed with little effort.

What must fit: Input = A (8Ohms), Output = B (2kOhms). The mounting direction must fit your case.
So any Accutronics: _AB__1_ can be used.
Thanks for this info! Very useful, as I was considering other tanks. I was hoping to use a medium to small sized tank. I realise the larger tank sounds "nicer" but I prefer the grungy sproinginess of the smaller tanks myself :spin:
(looking for more of an EMS vibe I guess)
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Post by fuzzbass »

Luap wrote:
Nordcore wrote:Are you really up for a *good* reverb?
Than a spring reverb might not be the best selection.

The 1AB2A1B seems to be original, that's one of the crappiest tanks they have ever made.
The BL2AB3C1B is larger (17", not 9") and has "long" reverb time.

You can use a lot of different tanks.

As this is DIY there is no need to select the "proper" input and output grounding, as that can be changed with little effort.

What must fit: Input = A (8Ohms), Output = B (2kOhms). The mounting direction must fit your case.
So any Accutronics: _AB__1_ can be used.
Thanks for this info! Very useful, as I was considering other tanks. I was hoping to use a medium to small sized tank. I realise the larger tank sounds "nicer" but I prefer the grungy sproinginess of the smaller tanks myself :spin:
(looking for more of an EMS vibe I guess)
Second what Nordcore said, the most important aspects for compatibility are the input and output impedance (the "AB" for Accutronics models).

Upgrading the reverb to stereo, with two springs may or may not be interesting. It would be the only thing on the synth that really was stereo in the sense of creating a spread. However there is only one spring drive, and one return circuit, so you would need a second pair of these running outboard.

Also, in its current state, the reverb circuit introduces a lot of noise, and adding a second identical one would double that. I'm going to be doing some experiments to see if this can be improved. Stay tuned.

Spring length is a matter of taste. If you don't limit yourself simply to the facilities of the TTSH, you can make short tanks have long decay, and long tanks have short decay.

To increase the decay time of a short tank, feed its output back into its input, with some added gain.

To decrease the decay time of a long spring, feed its output into a VCA and gate it with an EG. Gating a spring reverb is seriously addictive.
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Post by Nordcore »

Lower Noise:
Image
Can be build on the board w/o cutting tracks.
(Just swapping the op amp doesn't help anything, as the 22k is the main noise source. )

If "stereo" is meant as "mono in, stereo out":
The driver amp could drive 2 tranks, just add another 100Ohm (R281) for the second tanks drive coil.
Add another recovery amp (as above).
One supplies R212, one R213 (= Faders for reverb level left/right. )

Edit ... fixed typo in schematic
Last edited by Nordcore on Tue Jun 10, 2014 9:33 am, edited 1 time in total.
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Re: TTSH Spring Reverb

Post by Vcs3 »

sirg wrote:Half way through my build, trying to figure out what a good spring reverb to get would be, I don't have any experience building with one. So I'd be keen to hear peoples experiences or recommendations. The bom lists these two : Belton Accutronics 1AB2A1B
BL2AB3C1B from Banzai Electronics

I'm just wondering if anyone can say if they sound any good (those who like spring reverbs) or if there's anything better?

Also wondering about if it's worth going stereo, if that might sound cool?

Thanks for your advice!
I'm super happy with my Belton Accutronics 8AB2A1B! It's a medium length, well behaved, quality reverb tank. Very useful and pleasing.
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Post by Nordcore »

Comparing the (large) tanks "Accutronics 9AB2C1B" and "Belton RBL3AB2C1B" does reveal a huge difference in the efficiency of the mechanical decoupling. The Accutronics has a very soft suspension which effectively suppresses sound from the case to the spring. With the Belton you hear every touch / movement of the case.

I still have some hum (... mostly its overtones) - independent of the grounding scheme ... have to work on this. I do use the modified recovery amp as above, but it wasn't any better with the original.
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Post by roglok »

Nordcore wrote:Comparing the (large) tanks "Accutronics 9AB2C1B" and "Belton RBL3AB2C1B" does reveal a huge difference in the efficiency of the mechanical decoupling. The Accutronics has a very soft suspension which effectively suppresses sound from the case to the spring. With the Belton you hear every touch / movement of the case.

I still have some hum (... mostly its overtones) - independent of the grounding scheme ... have to work on this. I do use the modified recovery amp as above, but it wasn't any better with the original.
i'm happily using 9AB2C1B - sounds good to my ears.
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Post by ultravox »

I have the MOD 9AB2A1B reverb tank sold by AmplifiedParts. Nicely built and sounds great.
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Post by fuzzbass »

Nordcore wrote:Lower Noise:
Image
Can be build on the board w/o cutting tracks.
(Just swapping the op amp doesn't help anything, as the 22k is the main noise source. )

If "stereo" is meant as "mono in, stereo out":
The driver amp could drive 2 tranks, just add another 100Ohm (R281) for the second tanks drive coil.
Add another recovery amp (as above).
One supplies R212, one R213 (= Faders for reverb level left/right. )
I'm confused. I thought NE5532 was a dual op amp. Can you explain?

Also, Have you looked at whether the spring could be driven harder, thus reducing the gain requirement in the recovery amp?
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