For discussion about setting up your studio and advice on the gear and equipment within it.
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By Ill-Green Sat Dec 30, 2017 7:36 pm
Good day to all beatmakers, producers and Djs.

6 months ago, I bought a Roland Cube 30 to monitor my sampling and playing, plus listen to records instead of having multiple equipment powered on just to listen on a pair of KRK 8s. With the Cube, I can just have a sampler and turntable powered up and everything is dandy.

However, I just realized something about the Cube 30 that never caught my attention until now; it cancels out center frequencies! Here I'm thinking "when the hell did they made instrumentals for these albums and when did I bought them?" So I decided to dissect the issue by listening to the sampler itself through headphones and wadda ya know I hear the vocals, stereo intact. But out the Cube, I only hear the instrumental, which is cool in its own right but if I was to produce a beat and then master it to a DAW, that track would have random unintended vocals and sounds all over the place and I would have to craft the beat again by scratch. So I know its not the turntable's fault, I looked into the sampler and pulled out the left output and the vocals magically reappeared on the Cube 30. I pushed it back in and its an instrumental again. Same was done for the right output and same result. Sampler is good. So I do the same test for the Cube but for it's inputs and same result. Cube has 5 inputs and they all cancelled the center.

Now I take a Y cable, which combines a stereo signal into mono, connected the right and left outputs of the sampler and then plugged the lone side into Cube's Channel 1 input which is just one mono slot for XLR mics or 1/4" jacks. Should end the suffering right. Nope. I still get instrumentals. :hmmm:

I was wondering if anyone else has a CM30 and familiar with this problem. Would be cool to sample this stuff but unfortunately the Cube does not have line outs :fku: Good thing, I am only using it to monitor the beatmaking process but this is driving me mad.

Thank you in advance :worthy:
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By tapedeck Sat Dec 30, 2017 8:26 pm
sounds like the amp is mono and by jamming all those inputs into it, yer doing the classic phase-invert-cancel trick.

i think your only solution is to use it as intended...as a mono amp. pick either a left or right channel and just use that - or get another one to get true stereo. another, much more involved option, is to either use a computer to phase-invert one of the channels, see if that works better, or you could take a cable and rewire the ground to the signal and vice versa to invert the phase analog style.

but yea - that thing is designed for mono so it aint gonna play right w/ stereo.

fun fact: on the nine inch nails remix-record 'fixed' it actually included a warning about this very thing...it said it must be played on stereo systems or some of the music might cancel out. :mrgreen:
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By Ill-Green Wed Jan 03, 2018 1:27 pm
Thanks guys! I didn't expect answers so quickly. :worthy:

I read about having two Cubes for stereo image but the manual says its a stereo monitor, though the diagram shows left and right signal going out the speaker.
tapedeck wrote:sounds like the amp is mono and by jamming all those inputs into it, yer doing the classic phase-invert-cancel trick.

i think your only solution is to use it as intended...as a mono amp. pick either a left or right channel and just use that - or get another one to get true stereo. another, much more involved option, is to either use a computer to phase-invert one of the channels, see if that works better, or you could take a cable and rewire the ground to the signal and vice versa to invert the phase analog style.

but yea - that thing is designed for mono so it aint gonna play right w/ stereo.

fun fact: on the nine inch nails remix-record 'fixed' it actually included a warning about this very thing...it said it must be played on stereo systems or some of the music might cancel out. :mrgreen:


Thanks tapedeck!!

Lampdog wrote:I was just about to say, isn’t it mono?
Its weird, it doesn't mention being a mono amp, only by actual users on forums and blogs that verify it.

Wal Martian wrote:It's because you're sending two signals to a balanced mono input.
Ill-Green wrote: a Y cable, which combines a stereo signal into mono

A Y cable can't sum two signals together.


Depends on who manufactured the cable, some will just leave you with L Mono, other will give you L and R Mono mixed, there are also Y stereo cables. My Y cable is two RCA male jacks going into a mono 1/4 male jack, this one combines two signals into one output.
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By tapedeck Wed Jan 03, 2018 4:09 pm
Ill-Green wrote:...Depends on who manufactured the cable, some will just leave you with L Mono, other will give you L and R Mono mixed, there are also Y stereo cables. My Y cable is two RCA male jacks going into a mono 1/4 male jack, this one combines two signals into one output.

sort of... its actually technically a splitter so it is designed to work backward from how you are using. no competent engineer would design a cable that way and claim it was a mixer because thats just not how it works right. yes it is sort of a hacky side-effect that a lot of people use, but its just not good for signals or the gear involved to use it like that.
that will almost definitely cause problems down the road. just use one channel or get another monitor.
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By Lampdog Wed Jan 03, 2018 4:32 pm
Its weird, it doesn't mention being a mono amp, only by actual users on forums and blogs that verify it.

https://media.sweetwater.com/store/medi ... manual.pdf
Owner’s Manual, read's like it may very well be summed internally.

"In addition to a mic/line channel that provides an XLR-type
connector, there are two stereo channels and two stereo AUX IN
channels with RCA phono and stereo mini-jack connections, giving
you a total of five sets of inputs. These inputs can be combined
within the CM-30 by its stereo mixer."

What you can do is connect left and right inputs, use a mono cable for each. Balance source to left only and see if it plays through the cm30's speaker. Now try right only on source and see if it plays through to the cm30 speaker.
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By Wal Martian Wed Jan 03, 2018 6:01 pm
Ill-Green wrote: My Y cable is two RCA male jacks going into a mono 1/4 male jack, this one combines two signals into one output.

Your Y cable doesn't combine (sum) the signals, they still travel separately up the wire and stay on separate conductors on the 1/4" jack. A speaker with a balanced mono input needs a hot, a cold, and ground. With your cable you are sending hot L, hot R, and one common ground.
Image
Hot signal pushes the speaker out, and cold signal pulls the speaker in, but if you send the same signal to hot and cold, the speaker doesn't push out or pull in, it stays still. You are sending the left hot to hot, and the right hot to what is supposed to be cold, any identical signals (the centre channel) are cancelled. It doesn't depend on the cable, if you plug a TRS into an unbalanced (TS) input, sometimes you will get one of the two signals. In your case, since you are experiencing the phase cancellation of your L and R signals, the speaker has a TRS input.
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By tapedeck Wed Jan 03, 2018 6:51 pm
Wal Martian wrote:...if you plug a TRS into an unbalanced (TS) input, sometimes you will get one of the two signals. In your case, since you are experiencing the phase cancellation of your L and R signals, the speaker has a TRS input.

ding ding ding
think we have a winner
good explanation
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By Ill-Green Sun Jan 07, 2018 11:42 pm
Thanks men!! I'll definitely try those things. So far, its fine out the headphones but out that speaker, the center is cancelled. Its awesome to tell you the truth, I'm listening to instrumentals and it sounds clearer than with the vocals :lol: But its gonna **** things up.

Thanks Tapedeck, Lampdog and Walmartian!
By Linleechiun Wed May 06, 2020 5:10 am
Thanks for great discussion above.

I own a cm30, thinking about take one of the 6.35mm ts output to a Yamaha hs8 input. Since the cm30 manual said that it paired with another cm30 making true stereo and made both of them kind of" talking each other", then 2 cm30s can be input, sending another channel to another cm30.
So l assumed there is some chips in it to identify signal coming from the very same cable. Am I going to fry the circuit by line out to a non cm30?