CV Tools: Audio interface and cable adapter question.

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Faldoe
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CV Tools: Audio interface and cable adapter question.

Post by Faldoe » Sun Jul 28, 2019 8:10 pm

Can you use 1/4'' stereo to 1/8'' stereo adapters if you don't have 1/4'' to 1/8'' mono adapters? This is so I can trigger various patch points on my DFAM and Moog Grandmother.

Angstrom
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Re: CV Tools: Audio interface and cable adapter question.

Post by Angstrom » Sun Jul 28, 2019 11:14 pm

I'm confused here. Do you definitely have a DC compatible sound-card?
An audio interface which has 1/4 inch TRS connections is more likely to be a balanced mono out. If you plug a balanced TRS mono plug into such a socket it afts as a balanced cable amd the tip is inverted signal of ring. If a mono balanced T + R is summed by bridging them ... it is to zero. Plus I dont fancy that! You are short circuiting your audio out.

The only way to get a usable signal is a mono unbalanced cable. Assuming the device is actually outputting mono DC

Faldoe
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Re: CV Tools: Audio interface and cable adapter question.

Post by Faldoe » Mon Jul 29, 2019 10:26 pm

I'm using a Motu Ultralite MK3 which is DC coupled.

I actually have a random 1/4'' stereo to what I believe is 1/8'' stereo - did not check to confirm that latter - and it worked controlling the clock of my DFAM with the CV Tools Clock out.

stringtapper
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Re: CV Tools: Audio interface and cable adapter question.

Post by stringtapper » Fri Aug 02, 2019 6:56 am

You can have luck with signals that aren’t frequency dependent when using such a cable (like clocking, as you’ve found), but for anything more you’re going to need special cables to interface with Eurorack.

Expert Sleepers are the only folks I have ever seen selling these floating ring cables, but they are what you need.

https://www.expert-sleepers.co.uk/accessories.html
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TLW
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Re: CV Tools: Audio interface and cable adapter question.

Post by TLW » Sun Aug 04, 2019 7:41 pm

Assuming the MOTU can use mono jacks as well as TRS (and I’ve yet to see or hear of an interface that can’t, a mono jack simply carrying an unbalanced signal) I would expect a cable with a 1/4” mono jack at one end and a 1/18” mono jack at the other should work. They’re easily found on Ebay, at least that’s where I got my collection of them to handle synths with 1/8” mono outputs.

They’re also easy enough to solder yourself and soldered connections are far more reliable than using adaptors.

If the MOTU output has to be TRS then take a TRS cable, cut off the plug from one end and solder on a 1/8” mono jack with both cable cores connected to tip and the braid to ring.

Likewise a TRS to two mono 1/8” jacks is easy to make if they can’t be found ready-made.
Live 10.1 Suite, M4L, 2014/15 MacBook Pro 15.3” Retina i7, OS Mojave 10.14.5. RME UFX, assorted synths, guitars and stuff.

[jur]
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Re: CV Tools: Audio interface and cable adapter question.

Post by [jur] » Sun Aug 04, 2019 10:24 pm

TLW wrote:
Sun Aug 04, 2019 7:41 pm
Assuming the MOTU can use mono jacks as well as TRS (and I’ve yet to see or hear of an interface that can’t, a mono jack simply carrying an unbalanced signal) I would expect a cable with a 1/4” mono jack at one end and a 1/18” mono jack at the other should work.
That's what I use, and that's the solution.
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stringtapper
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Re: CV Tools: Audio interface and cable adapter question.

Post by stringtapper » Mon Aug 05, 2019 4:10 pm

[jur] wrote:
Sun Aug 04, 2019 10:24 pm
TLW wrote:
Sun Aug 04, 2019 7:41 pm
Assuming the MOTU can use mono jacks as well as TRS (and I’ve yet to see or hear of an interface that can’t, a mono jack simply carrying an unbalanced signal) I would expect a cable with a 1/4” mono jack at one end and a 1/18” mono jack at the other should work.
That's what I use, and that's the solution.
You use a mono 1/4" –> mono 1/8" with a MOTU interface to send CV? What kind of signal range are you getting from it?

I never had any luck with that. The Expert Sleepers cables are the only thing I've been able to get (almost*) a full signal from MOTU interfaces.

*The MOTUs I've used (UltraLite mk2, 828mk2, 828x) have all only gotten about 4.5v± output even with the Expert Sleepers cables. I have started using my UAD Apollo 8 with my Eurorack rig and I'm getting around 5.5v± with that.
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TLW
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Re: CV Tools: Audio interface and cable adapter question.

Post by TLW » Tue Aug 06, 2019 6:48 pm

I have an RME interface and don’t use it to send CV at all (it’s a UFX and they’re not DC coupled).

I use 1/4” to 1/8” mono jack leads for both CV between devices and for audio.

I note that according to Expert Sleeper’s website they suggest a TRS to TS cable with the ring not connected is the way to handle voltages from CV coupled interfaces. What they say makes sense, so I’ve learned something. Thanks for pointing that out.
Live 10.1 Suite, M4L, 2014/15 MacBook Pro 15.3” Retina i7, OS Mojave 10.14.5. RME UFX, assorted synths, guitars and stuff.

Angstrom
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Re: CV Tools: Audio interface and cable adapter question.

Post by Angstrom » Tue Aug 06, 2019 7:39 pm

TLW wrote:
Tue Aug 06, 2019 6:48 pm
I have an RME interface and don’t use it to send CV at all (it’s a UFX and they’re not DC coupled).
On your RME you have two ADAT outputs.
Each of those can send 8 channels down a fibreoptic cable

If you have the cash for an ES-3 you can turn those 8 ADAT channels into 8 DC coupled voltage outputs.

https://www.expert-sleepers.co.uk/es3.html

the Es-3 is about £170 in my country.

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TLW
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Re: CV Tools: Audio interface and cable adapter question.

Post by TLW » Tue Aug 06, 2019 10:38 pm

An interesting module, thanks. It's £170 in my country as well :-)

I don't have a modular at the moment, just an assortment of "semi-modular" synths and a couple of sequencers and guitar fx that can use CV. I do keep getting tempted by modular stuff though.... maybe one day.
Live 10.1 Suite, M4L, 2014/15 MacBook Pro 15.3” Retina i7, OS Mojave 10.14.5. RME UFX, assorted synths, guitars and stuff.

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