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2600 clone - Two Thousand Six Hundred (TTSH)
MUFF WIGGLER Forum Index -> Music Tech DIY Goto page Previous  1, 2, 3 ... , 166, 167, 168  Next [all]
Author 2600 clone - Two Thousand Six Hundred (TTSH)
tobb
synthcube wrote:


Of course, comments and feedback from this community are welcome! If we proceed, order details will follow in a separate thread.


Cool would be to have PCB component patterns for using faders w/o led shafts and the option to use switchcraft tini jax sockets.
synthcube
Jaytee wrote:
Unrelated to rev 4, but of interest to TTSH builders of all revisions: http://synthronics.de/dust-covers-ttsh-arp-2600/

Someone who makes slider dust covers for vintage synths just released a set for the TTSH. I recall there had been at least a few questions about this over the years.


thats an awesome find-- thank you for posting --- we'll contact those folks, seems like the dust cover set would be a good addition to a full and updated TTSH kit
sduck
Jaytee wrote:
sduck wrote:
Jaytee wrote:

For reference on price, the Enigma alpha PCBs (no panel) cost about twice what I paid for the TTSH PCBs and panel during the last run.


I didn't realize the price of the third run had dropped so much - the first run of the TTSH cost about the same as the enigma pcbs. Of course used sets can be found a lot cheaper, but the originals were about the same price. The price of the panel (enigma) is still up in the air, so to speak.


Yeah, I remember the first run was quite a bit more expensive. I don’t know how much was the listed price actually dropping and how much of it was a more favorable exchange rate as time went on, but by the third run it was a lot less pricey. I think the exchange rate has only gotten more favorable since then even, but I don’t know if that’ll matter WRT rev4 with Synthcube taking over.


What did you pay for your pcb/panel set? I know the exchange rate fluctuates, but I'm just curious what it actually ended up being for you (if you remember, of course). For the first run, it ended up being right around 700$ for the pcb/panel, and another 200$ for the metal case. This is US dollars, btw.
Jaytee
sduck wrote:
Jaytee wrote:
Yeah, I remember the first run was quite a bit more expensive. I don’t know how much was the listed price actually dropping and how much of it was a more favorable exchange rate as time went on, but by the third run it was a lot less pricey. I think the exchange rate has only gotten more favorable since then even, but I don’t know if that’ll matter WRT rev4 with Synthcube taking over.


What did you pay for your pcb/panel set? I know the exchange rate fluctuates, but I'm just curious what it actually ended up being for you (if you remember, of course). For the first run, it ended up being right around 700$ for the pcb/panel, and another 200$ for the metal case. This is US dollars, btw.


Just searched through my email inbox. My invoice from THC was 3200kr + 498kr for shipping. According to the fraud alert email I got hihi that came out to $405 US for PCB and panel + shipping. I built my own case so unfortunately not sure what that cost during rev3.
LED-man
Jaytee wrote:
Unrelated to rev 4, but of interest to TTSH builders of all revisions: http://synthronics.de/dust-covers-ttsh-arp-2600/

Someone who makes slider dust covers for vintage synths just released a set for the TTSH. I recall there had been at least a few questions about this over the years.


Yes, Andrew got from me a TTSH Panel and arp1601, SY-1M Panel to create the covers, which must be glued on the panels.
I get on Tuesday the first covers and report about the installation here and on my website.
ultravox
It's great that you guys are keeping the TTSH going.
It's an awesome synth and I'm looking forward to seeing what you come up with in Version 4.
AonFLuX
Hope for some extra metal-cases as I did not buy one last time. And of course have not bothered to build my own yet..
fuzzbass
Warning: opinions.

Synthcube: There are some things I like about THC's TTSH V3 version, such as moving the DC-DC converters a little further from the filter, and adding proper RCA jacks for the reverb. For me the 4072 filter is meh, but I'm sure it has its advocates.

However:

1: Bugs, hideous ones, and many. For this money, builders should expect something that works if they build correctly;

2: [edited since first posted] The connection between the KBD CV OUTPUT jack and the CV header on the main board should be corrected. Currently, the tip-switched contact of the jack is connected to 0V, defeating the header. This connection is hard wired , and seems to be in the middle layer and thus uncuttable. This is also not depicted on the V2 or V3 schematics. It is a problem when the system is built with a pitch CV source internally (ex: MIDIImplant, 3620 keyboard, etc). The tip-switched pin should be routed to the hot pin on the header. From there, the builder may either connect an internal CV source, or place a shorting jumper to 0V.

3. Change the footprint/BOM for the noise transistor to BC337-16 low gain type, and add a 10K resistor in series with the 1uf cap on the emitter. I think LED-Man may disagree with the second change. However, both of these changes have turned out to be needed on my builds.

Hopefully these issues will be corrected, and a beta build performed, before the next TTSH project hits the market.

(thinking I was done building these things. HA!)
Jaytee
Agree with the suggestions Fuzzbass has made.

The vias underneath the jacks is a critical bug and definitely needs to get fixed. I assume this is one of hideous errors Fuzzbass is referring to, but just wanted to say it specifically. The other bugs are not quite so bad, but I agree that after four revisions, it would be nice to finally be rid of missing traces and incorrect component footprints. I won’t bother listing the minor errors since they’re all documented on DSL-man’s site.

The LED driver circuit should be corrected as well—this is not listed as a bug on DSL-man’s site, but I’ve seen it confuse new builders. In Rev 2, a circuit was added to the LEDs to delay them coming on, but it never worked correctly. The generally agreed-on solution is to leave out most of that circuit and to jumper two legs of the op-amp footprint in that area. Fuzzbass has also shown that by replacing one of the resistors in the same area with a jumper, the LEDs can be trimmed to completely off. Can’t really see any reason why these changes shouldn’t be incorporated into the PCB.

Some sort of protection on the headphone out would be greatly appreciated. *So many* people have fried part of their power amps by accidentally plugging a mono cable into the stereo headphone jack and thereby shorting one channel’s output to ground. The commonly accepted solution here is simply “don’t plug a mono cable into the headphone jack” but for an instrument this nice, some kind of actual protection is warranted IMHO. Unfortunately I’m too much of an electronics dunce to actually suggest a possible fix.

Speaking of the power amps, it’s also come up that the specced Peerless speakers (8ohm impedance) are not a good match for the 2600 amps, designed for the 40-45ohm speakers in the original. It can cause issues when there’s low frequency content going through cranked speakers. Again, generally accepted practice here is simply “don’t do that.” My personal solution was to use some 45ohm speakers I found that are the correct footprint (https://www.jameco.com/z/FEB30045-Arndt-45-ohm-Square-Alnico-Speaker- 90-dB_2236674.html), but they’re cheap, lo-fi speakers and probably not to everyone’s taste. I’ve also heard impedance-matching transformers suggested as a fix (this is actually what they used on some early 2600s), but finding a correct part was more of a chore than I wanted to deal with. Perhaps there are tweaks that could be made to the power amp circuits, but again, I’m not experienced enough to suggest one. This is not a huge issue in practice, but it would be nice if an easy fix were found all the same.

Other stuff; not important at all but would be cool, so long as adding them doesn’t create more PCB errors...
- Offer the PSU board for sale on its own, as well as bundled with the main PCB. The issue here is that the DC/DC converters can fail (as one did on my own build), and that desoldering them is a complete nightmare. Would be nice to have peace of mind that if your PSU board gets destroyed from trying to remove a bad DC/DC converter, that there are replacements available.
- Integrated gatebooster? Or, barring that, at least an integrated mounting location (some bolt holes to install spacers)?
- Protoboard section/s? Would be cool to be able to build some mods directly on the PCB, and it’s not as if there’s a lack of space...
- Bigger cutouts at the top corners of the main PCB. There is almost no clearance for panel-mounting hardware to go past the PCB at these two points. Becomes a minor problem when building custom cases.
- Would be cool if the electronic switch clock mod were integrated into the PCB with an optional jumper or something.
chuckg
I'd love a ttsh!
fuzzbass
chuckg wrote:
I'd love a ttsh!


To sample one is to hold one.
JanneI
I agree with fuzzbass and Jaytee. I didn't even remember the via's -thing very frustrating These all should absolutely be fixed since it's already revision #4. No excuses valid if they are just left there. Then it's purely money that matters now that ttsh is not the only player in the field. Imho.
synthcube
AonFLuX wrote:
Hope for some extra metal-cases as I did not buy one last time. And of course have not bothered to build my own yet..


yes, we will be making and offering these
synthcube
jaytee and fuzzbass et al
(not using quote feature so as to reduce duplication of words)

THANK YOU for the opinions and feedback. These, along with LED-Mans notes are all going into a 'master list' of proposed PCB and BOM changes.

So Jon has committed to making corrections, so we'll be arranging these with him, and sharing the details about what is different via this thread and other forums.

It is our plan to offer a more complete build guide, BOM, etc by consolidating prior project feedback, new documentation etc as well as a beta test period.

Listen, we love the TTSH and wouldn't be spending time on the next run if we didn't. We also know it wasn't perfect, and we are committed to this next iteration being improved- probably not perfect again, but improved to be good value for the money and a serious instrument for people who invest their time and $$ in building it.
synthcube
LED-man wrote:
Jaytee wrote:
Unrelated to rev 4, but of interest to TTSH builders of all revisions: http://synthronics.de/dust-covers-ttsh-arp-2600/

Someone who makes slider dust covers for vintage synths just released a set for the TTSH. I recall there had been at least a few questions about this over the years.


Yes, Andrew got from me a TTSH Panel and arp1601, SY-1M Panel to create the covers, which must be glued on the panels.
I get on Tuesday the first covers and report about the installation here and on my website.


please let us know what you think of the dust covers, we value your opinion about it, thank you!
Jaytee
That all sounds absolutely ace. The consolidation of build notes and documentation will be especially nice. And while I’d love to see everything on my wish list checked off, I think so long as the major bugs and PCB errors are taken care of, it’ll be solid.

Thanks for working on this (and send thanks along to Jon as well!)
fuzzbass
Jaytee wrote:


Fuzzbass has also shown that by replacing one of the resistors in the same area with a jumper, the LEDs can be trimmed to completely off.



Credit where due. My recollection is that sduck worked that out. If that is wrong, I'm still certain I got it from someone else.

Jaytee wrote:


Some sort of protection on the headphone out would be greatly appreciated. Etc...



The amps/speakers/phones section behaves as designed, so I would not list this as needing a fix, and probably outside scope of what Jon may have agreed to with Synthcube.

Still, the way to deal (IMO) would be to separate the headphone circuit from the speaker outputs. You can buy lots of different all-in-one stereo phones driver chips for pennies. Would require its own attenuator, but there is space for that in the area of the TRS jack. I would not weigh down the TTSH V4 with this, it can exist as a mod. I nominate Jaytee to invent this...
Jaytee
fuzzbass wrote:
Jaytee wrote:
]

Some sort of protection on the headphone out would be greatly appreciated. Etc...



The amps/speakers/phones section behaves as designed, so I would not list this as needing a fix, and probably outside scope of what Jon may have agreed to with Synthcube.


I’ve never been able to confirm this: does an actual 2600 blow its power amp when a TS jack is plugged into the headphone out? As you mention, according to the schematics it should, but I’ve been wondering if this is a situation where the actual units differ from the service manual. It just seems like an odd oversight on an otherwise well-designed synth, and given how commonly it’s been a problem with the TTSH, one would expect an issue like this to have been somewhat notorious on the 2600 itself...but I’ve never been able to find any reference to such an issue.

Anyway, that’s neither here nor there, but I’ve just always been curious.

As far as fixing it on the TTSH, my only argument in favor of fixing it is that it’s caused problems for quite a few builders. But yeah, it’s not really an “error” to be fixed, since it is faithful to the original schematics.

Quote:
Still, the way to deal (IMO) would be to separate the headphone circuit from the speaker outputs. You can buy lots of different all-in-one stereo phones driver chips for pennies. Would require its own attenuator, but there is space for that in the area of the TRS jack. I would not weigh down the TTSH V4 with this, it can exist as a mod. I nominate Jaytee to invent this...


So, I was hoping that someone might pipe up with a very simple solution like “oh, just put this diode here” that would be easy to add to the TTSH. I can’t conceptualize any solution this simple, but that’s not surprising given my lack of expertise.

That said, if there’s no “silver bullet” solution like that, then I really like this idea of adding a separate headphone amp. I’m gonna look into this.
LED-man
Come on, that’s all on improvements and fixes ?

I wait few days with my list, I want see more here.
fuzzbass
Jaytee wrote:
I was hoping that someone might pipe up with a very simple solution like “oh, just put this diode here” that would be easy to add to the TTSH.


You absolutely could put diodes across the output. Of course, due to the diode voltage drop and this being a push-pull amp, it might sound like a fuzzbox in normal operation. Rockin' Banana!

OK LED-Man you asked for it...

Gate boost plus trigger generation could be built-in. Even better would be to do it with OR gates instead of comparators, thus allowing multiple gates and triggers to be aggregated (ex: 3620 + some sequencer)

An EASY improvement would be to add PW control in VCO1 by replacing the symmetry trimmer with a slider.

Add a switch to VCO1 and VCO3 wherein one of the FM Control mixer channels could be rerouted to be a PWM control. Requires additional circuitry in the pulse shapers.

Add a second unity gain inverting stage to one or both voltage processors, so they also had non-inverting outputs.

The Electronic Switch clock source mod could be formalized.

The AR diode to transistor mod could be formalized.

The range selectors for the AR and ADSR could be formalized.

There could be some additional M3 holes around the main PCB so add-ons could be mounted and reverb wires could be dressed away from bleed signals.

Panel mount points could be increased from four to eight.

Init Freq and 1V/Oct scale trimmers could be changed to 20 turn types.

There is something defective in the design of the LED clock rate flasher, which heats up too much considering that the LED is not overly bright. Maybe it is conducting when the LED is off...

The BOM could specify a 22n polystyrene cap for the Sample and Hold.

Lag Generator cleaned up to require TL071 and eliminate 30p compensating cap, which TL071 does not need. TL081 is even better, lower offset choice.

Balanced audio outs on 6.3mm TRS jacks, anyone?

Replace the crummy sine shaper in VCO2 with a better one.

Is that enough or should I go on?
Jaytee
This suggestion is specific to the Synthcube parts kits (which I’m assuming will be a thing again). The male RCA jacks included for making one’s own reverb cables are not very functional. I’m honestly not sure how one is meant to make cables from them; there’s no obvious place to connect the wiring, either by soldering or otherwise. Also, IIRC, there were only two supplied while you need four to build the cables as of Rev3 (though I don’t think this was known when Synthcube was assembling the Rev3 kits).

It’s not a big deal, since the kit already came with a regular RCA cable, and new plugs are super cheap anyway, but figured it was worth mentioning.
fuzzbass
Jaytee wrote:
This suggestion is specific to the Synthcube parts kits (which I’m assuming will be a thing again). The male RCA jacks included for making one’s own reverb cables are not very functional. I’m honestly not sure how one is meant to make cables from them; there’s no obvious place to connect the wiring, either by soldering or otherwise. Also, IIRC, there were only two supplied while you need four to build the cables as of Rev3 (though I don’t think this was known when Synthcube was assembling the Rev3 kits).

It’s not a big deal, since the kit already came with a regular RCA cable, and new plugs are super cheap anyway, but figured it was worth mentioning.


Synthcube included those on my recommendation so blame me. They have fixed the quantity issue. The idea is to use antenna grade coax and cut the runs to fit. Both of these steps significantly reduce noise being picked up on the return line. Cables made for connecting consumer audio devices are deficient in this application. Coax wire and these exact plugs (which are made for coax wire) were used to connect spring reverb on old Fender and other amps.

Here is how you use them. Measure and cut your coax to minimize the cable length, position your reverb tank so the return line is the short run. I use RG174 and I believe this is what Synthcube includes in the parts kit. Strip the outer insulation back 1 and 3/8 inches, and the shield loom+inner insulation to 1 inch, exposing the inner copper strands - give those a twist. I have a little coax stripper that does it one pass. You will need a small vise to hold the jack.

Unweave the shield loom and pull back to the outer jacket. Pull off the insulation from the inner connector. Insert the inner wire into the jack until you see copper strands coming out of small hole in the tip of the plug, and the shield loom is touching the outer part of the jack. Make sure none of the shield strands go into the jack. Solder the shield loom to the outer part of the jack, distributing the strands around it so as to provide some strain relief. Using thin solder wire (I use .031), push a little bit of solder wire into the hole in the tip (where the copper strands are coming out). Apply your soldering iron to the plug tip and heat until the solder runs. Push about 1.5 inches of solder wire into the hole as it melts, to fill the plug tip. When you see solder coming back out of the tip, you are done. Snip excess copper wire and carve away any excess solder on the tip. If any flux came out, clean that up. Test for shorts/opens.
Jaytee
Well hey, TIL. I spent a few days puzzling over those RCA jacks. I eventually just figured they were made for some kind of commercial assembly.
fuzzbass
Naw, they are made for old school hand assembly. But I like them a lot because they work very well with coax, and have a really small profile.
doobedy
Is rev 4 a real possibility? w00t
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