Incoming Project: Output and Multiple for 5U

[Synthbuilder]

This is probably my last MOTM format 5U module I will design, as any new modules will be specifically for MU or Eurorack. It was just over twenty years ago when the first Oakley MOTM format module was created - the original Superladder - so we've certainly had a good run.



The Oakley Router is a simple but useful module. The top section is two passive multiples.

The lower section contains four identical inverting amplifier circuits. The amplification can be set when building the unit but the suggested gains are either -1, -0.33, or -0.1. Each output is balanced and uses a 1/4” TRS (tip ring sleeve) socket which can be connected directly, using a balanced cable, to a balanced input of an audio interface or mixing desk without introducing ground loops. The outputs can, however, also be used with unbalanced inputs, and the outputs will not be damaged if you use standard mono unbalanced (TS) cables.

Each of the output amplifiers are inverting, that is a positive going signal is turned into a negative going signal. This has no audible effect on the audio signal but will change the polarity of any control voltages passed through it. The module could thus be used as an effective quad inverter if required.



More information:

http://www.oakleysound.com/router.htm

The Builder's Guide will be ready in the next few days.

Tony

[Pav]

was hoping for something more useful to me to finish my case to be honest. For new builders will be useful of course. I already have multiples, and have no issues with unbalanced to balanced outputs with a Mackie 1604 mixer via a separate patch bay. ( or do I, and do not know I have them?)

Leaves the question what use cases I can drum up for a quad inverter

[Synthbuilder]

was hoping for something more useful to me to finish my case to be honest.

Yeah, I don't see these flying off the shelf. I only built it because I needed it to finish off my rehoused small system.

For new builders will be useful of course.

Very few new builders now. The number of MOTM orders per week, including from older customers, is now usually less than three. Just one MOTM board sale last week.

or do I, and do not know I have them?

Slap your modular input on a spectrum analyser. I get quite a bit of 50Hz and its harmonics (mostly 150Hz) when I use unbalanced connections from my modular. It's less -80dB but you know, if I can make it drop below -100dB with balanced drivers I will.

Tony

[Pav]

Good tip .. thats 2 uses for getting a spectrum analyser plug-in -the other to finesse the AVS filter calibration.

[welhamc]

Very sad to hear that this is likely to be the last 5U module Tony. Do we now need to panic about existing stock of PCBs? I still have lots of modules I plan to build!

[Synthbuilder]

Very sad to hear that this is likely to be the last 5U module Tony.

Thankfully, it won't be the last 5U module. I hope to be developing a range of MU (ie. Synthesizers.com compatible) modules. Some of them will be ports from the MOTM format, others will be new. Most of my single width modules can be used in MU builds already, but getting panels made in that format is not so easy in small quantities.

Do we now need to panic about existing stock of PCBs? I still have lots of modules I plan to build!

No need to panic. So long as there are sufficient people still wanting to purchase boards I'll keep them in stock. The existing Oakley MOTM format covers a great deal of ground and I hope existing owners of the format will continue to build Oakley modules.

Tony

[welhamc]

Perfect, thanks Tony, all your work is hugely appreciated, its such a shame that there seems to be a decline in DIY builders

In terms of new the future MU modules, are there plans to allow for cross compatibility with existing MOTM systems? (Ie will it just be a case of altering panels for MOTM/installing MTA power headers?)

[Synthbuilder]

Perfect, thanks Tony, all your work is hugely appreciated

... its such a shame that there seems to be a decline in DIY builders.

I don't think there is a decline. They're just building stuff in Eurorack. Mostly from full kits, and then from kits that have the panel provided. Which means I need to do something about getting some cheap panels made for all my euro stuff.

In terms of new the future MU modules, are there plans to allow for cross compatibility with existing MOTM systems? (Ie will it just be a case of altering panels for MOTM/installing MTA power headers?)

MU panels are wider and although using a single width 1U MOTM design fits well enough behind a single width 1MU panel, it starts getting a little spaced out when we go to 2MU or 3MU. So any MOTM design will fit into MU but may not be that ergonomic. The opposite is not true. A single width MU module will not fit behind the smaller single width MOTM panel. So my new stuff which will be designed for MU will almost certainly not fit behind a MOTM sized panel.

Interestingly, my first MU design was the ASV which by a quirk of the maths does fit behind a MOTM sized panel. The reason being that 4MU is just a tad narrower than 5U. So anything I do that big will be compatible.

I will continue to put the 4-way MTA156 or Molex connectors on any new 5U board. The larger connectors are better than the little MU offering - so if anyone is planning an all Oakley MU system they'll be able to use the superior MOTM style power header.

Any new MU design will also come with panels. Availability of panels has always been a problem with MU. Getting a bespoke panel made is expensive and can be quite a wait. I think the waiting problems may now be over so I hope to be able to offer high quality panels with any new 5U PCB design. I've got the new ASV panel here and they look fabulous. The production run for those will start shortly.

However, if we get a poor trade deal (ie. not free for small value orders) with the EU or other countries overseas, all of this may be moot. If my overseas customers have to pay an additional VAT and handling charge, even for an order of only one board, then it's time for a Plan B. This may involve me giving up on this PCB lark entirely or getting someone like Thonk to sell my stuff.

Here's a quick render of the ASV panel for MU - they'll be some proper photos shortly.



Tony

[Blake Smith]

Sad to hear MoTM designs are ending. It sounds like I'm in the minority preferring that over MU, but my MoTM synth is expansive enough at this point and I'm ending up with a bit of everything anyhow. Anything that keeps the excellent designs coming is great.

[tvh]

Happy holiday season, everyone.

Tony - question on the multiples/output module - I've been using the classic VCA as my output->mixer (a soundcraft FX16ii), but that is an unbalanced connection if I'm not mistaken. Would a use case be classic vca-->new output module-->mixer? Does the module just attenuate the signal for use in equipment that needs a lower level input (pedals, some interfaces)?

Your new, yet to be announced MU modules will also be +/-15V, right? Would there be a difference in pot spacing between MOTM and MU? I know MU panels are much larger, relatively speaking, and I'm thinking of your method of using the pot brackets which is super convenient and sturdy. What would be the barrier(s) in adapting a MU pcb to MOTM panel?

On a side note...I've had to take a break from modular DIY for a few years (new child) and just now getting back into it - just built a new case to hold 3 rows of 22U in anticipation of building my dream rig, and then we get this announcement lol.

[Synthbuilder]

I've been using the classic VCA as my output->mixer (a soundcraft FX16ii), but that is an unbalanced connection if I'm not mistaken. Would a use case be classic vca-->new output module-->mixer?

Yes. This is exactly the output chain I use. The outputs on all Oakley 5U modules with the exception of the Router are unbalanced on TS sockets only.

Does the module just attenuate the signal for use in equipment that needs a lower level input (pedals, some interfaces)?

The single amplifier stage can set up for any chosen gain. I use -10dB (0.33) on mine because my RME interface seems to behave better with a lower signal. I give some recommended values for unity gain (0dB), 0.33 (-10dB) and 0.1 (-20dB) in the Builder's Guide - but other gains can be done simply. And each channel can have different gains should one wish - although there is no easy way to change them on the fly.

Your new, yet to be announced MU modules will also be +/-15V, right?

Actualy, the ASV is the first of the MU modules. It just so happens that 4MU is just a tad smaller than 5U so will fit into a 5U panel nicely. But, yes, all MU modules will be +/-15V and will have both MOTM and MU style headers on them just like my other 5U modules.

Would there be a difference in pot spacing between MOTM and MU?

Expect big differences here. I will be using PCBs parallel to the front panel - like the ASV and my Euro modules - which means pot spacing will be all over the place with no set rules any more. Panels will be designed for ergonomics and will move away from the relatively rigid grid system of the MOTM format. The parallel to panel board structure is a little harder to make and test, but allows for very shallow modules which a lot of folk want these days.

What would be the barrier(s) in adapting a MU pcb to MOTM panel?

I think it will be nigh on impossible. But many of the new MU designs will simply be conversions of the existing MOTM format modules. For the first few years I don't think you'll be missing out on anything new... with the possible exception of the forthcoming 2MU wide delay.

just built a new case to hold 3 rows of 22U in anticipation of building my dream rig, and then we get this announcement lol.

I hope to be able to keep most of the current stock of boards available. However, if sales do drop appreciably on any specific module then that will be discontinued. I'll try to let folk know, via the PCB stock announcement post and on the News page on the website, if I do intend to drop any design. For example, the old Dual-VCA and Discontinuity will be discontinued as soon as current stocks are depleted.

Tony

[tvh]

Thanks Tony for the info. I guess I was a bit late to the MOTM party but I do like the format/spacing. I started a few eurorack modules awhile back and I still can't believe how tiny these are in person. We're a bit spoiled I guess.

[Paradigm X]

oh thats a shame, but i havent ordered anything in ages so cant grumble. various life things have taken over and havent really done anything in ages. :(

THe output model funnily enough does look like soemthing i need so will probably grab that.

[Paradigm X]

just had a thought while doing the washing up

can you set the gain to more than one?

i was thinking i would unlikley use 4 outputs, but if you had say channel 4 as plus 20dB and 3 as -20dB, youd have a nice stomp box fx loop, and also boost tm3030 levels up to modular too! like a fixed gain preamp. Doubly useful!

[Synthbuilder]

can you set the gain to more than one?

You can pretty much set it to anything (within reason). It's just an op-amp inverting amplifier in there so the usual rules apply.

Rf/Rin = Av

Rf is the feedback resistor
Rin in the input resistor, which also sets the input impedance.
Av is the voltage gain

In reality Rin doesn't want to be much below 10K, so for +20dB where Av is 10, I'd chose something like Rin = 10K and Rf = 100K. The feedback capacitor would be something like 10pF.

Tony

[Paradigm X]

thats great, thanks, i guessed there would be a formula for gain. a 3out/1in module would be super useful. ill order one when i get paid.

many thanks
Ben

[Paradigm X]

Hi, another query, what would happen if you accidently applied phantom power to an output on the module? my mixer stupidly has the same shape and size switch for phantom power right next to the power switch, hidden at the back, so its easy to accidentally turn on phantom power. i havent got any xlr inputs yet so its never been a problem.

Ill gaffa it off if need be!

cheers

[Synthbuilder]

What would happen if you accidently applied phantom power to an output on the module?

Not sure. It might survive but very possibly not. I didn't put any extra protection on the outputs bar what's in the OPA2134s.

Tony

[Paradigm X]

ok best gaffa tape it up then! thanks, all the best

[terjewinther]

This is probably my last MOTM format 5U module I will design, as any new modules will be specifically for MU or Eurorack. It was just over twenty years ago when the first Oakley MOTM format module was created - the original Superladder - so we've certainly had a good run.
...
The Oakley Router is a simple but useful module. The top section is two passive multiples.

Well, I built this, and it works like a charm. Set up two of the input-outputs for 0db, and the other two for various lower options, so I can use guitar pedals or whatever. Put this in the middle of my modular, so the mults will be useful, and I am looking forward to the first concert I am using this. It might have a noticeable effect on the final output, as on concerts the volume can get quite high sometimes, and often noise and various other bits follows. Also in the studio I might notice some subtle difference when running directly into the recording rig with balanced inputs.

Sad that this was the last MOTM style 5U project. I do have MU modulars as well, so I am looking forward to any MU modules coming out. Front panels are more important in MU, of course, so it might be worth considering selling front panels as an option when offering MU modules.

It has been very good to be an Oakley customer, builder and user all these years. Still enjoy it all, and use the modules almost every day. They are the best.