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RME User Forum → ADI-2 & 2/4 Pro series, ADI-2 DAC series → 2 Pro connected to active Stereo Speakers. How to connect to Subwoofer
I have an ADI-2 Pro FS R Black Edition connected with XLR cables to each of a LEFT and RIGHT active speaker.
Now I want, in addition, to connect the ADI-2 Pro to one Velodyne SPL-1200 Ultra Subwoofer.
How can I connect the Stereo OUTPUT on the ADI-2 Pro to the ONE CINCH/RCA INPUT of the Velodyne SPL-1200 Subwoofer?
Please advise.
Just connect both... Or one to the input marked LFE.
Just connect both... Or one to the input marked LFE.
Thank you for your feedback.
I may have expressed myself not clearly enough.
The question is which OUTPUT connection on the RME 2 Pro I should use. Should I use the OUTPUT of the 6.3 mm TRS jack on one end on the RME 2 Pro and at the other end to the LFE INPUT on the Subwoofer?
Can I use the 6.3 mm TRS Jack to connect to the Subwoofer, while at the same time my active Stereo speakers are connected using the XLR connection?
Yes and yes.
Your Velodyne SPL-1200 has two RCAs marked “Input”.
Use two 6.3 mm TRS (or TS) to RCA cables to connect these to ADI-2 Pro’s
Rear TRSs.
If you just used one cable, you would get subs from left channel only, but not from right (or vice versa).
Your Velodyne SPL-1200 has two RCAs marked “Input”.
Use two 6.3 mm TRS (or TS) to RCA cables to connect these to ADI-2 Pro’s
Rear TRSs.If you just used one cable, you would get subs from left channel only, bot not from right (or vice versa).
A great many thanks for your solution, KaiS
Your Velodyne SPL-1200 has two RCAs marked “Input”.
Use two 6.3 mm TRS (or TS) to RCA cables to connect these to ADI-2 Pro’s
Rear TRSs.If you just used one cable, you would get subs from left channel only, bot not from right (or vice versa).
Oooppss, the Velodyne SPL-1200 only has a LFE INPUT, which is a FEMALE CINCH/RCA INPUT. The 6.3 mm TRS is a MONO OUTPUT on the rear of the RME 2 Pro. So, I need one cable with a 6.3 mm TRS MALE connector on one end and a CINCH/RCA MALE connector for the LFE CINCH/RCA FEMALE input on the Velodyne.
So, I have to connect as confirmed by RME Support.
I saw that, but does that mean the other RCA input is actually inactive? Why would they install an inactive input? So I would think is that LFE is just where you connect dedicated (mono) LFE signal from a surround sound source, but you can also connect regular mono... Since most low bass content won't be panned much anyway, either solution will work.
... Since most low bass content won't be panned much anyway, either solution will work.
This is a common myth that’s not quite right.
Being a recording engineer and music producer, without going into detail, I can assure that almost every recording contains significant amounts of stereo bass.
Using only one channel, some information is lost.
Buying a quality sub like the Velodyne, then compromising the sound by sparing one cable doesn’t make sense.
I’ve tested it:
If the Velodyne (not clear which exact version of the sub we’re talking about, so I can’t search it) indeed only has one input, an RCA y-adapter can be used, combining left and right outputs of ADI-2.
(ADI-2’s internal resistors are preventing any detrimental effects like increased distortions).
Available in various lengths:
https://amzn.eu/d/0cYM2KTg
I said most, and a subwoofer doesn't really have a stereo position anyway. Whatever is stereo will appear as such on the main speakers as such. Worst case you'd lose some signal level if sub bass content were to be so panned as to really make a difference. Anyway, my assumption would be that both inputs are active, and the one they suggest to use for mono input is marked LFE...
Edit: And the manual confirms that of course both inputs are active, so that doesn't really matter here anyway...
RME Support wrote:... Since most low bass content won't be panned much anyway, either solution will work.
This is a common myth that’s not quite right.
Being a recording engineer and music producer, without going into detail, I can assure that almost every recording contains significant amounts of stereo bass.
Using only one channel, some information is lost.
Being a die-hard sub-bass fan with the matching equipment to analyse, listen and feel it, I disagree. It also makes no sense, as the lowest bass is not directional, so panning that frequency range would just lose volume/power in reproduction, but not bring any audible difference.
If I find 'stereo' bass in recordings (seldom enough) it's typically used to widen the bass sound, not being boringly centered and getting some 'ambience'. But what makes the 'stereo' sound of it is all above 80 Hz, and therefore not relevant for the sub.
Sub bass in stereo would make sense for headphone listening. Then again - how many ppm of headphone users do listen to such lowest frequencies intentionally (needs special phones plus lots of EQ)? I know I'm part of a dying breed...
KaiS wrote:RME Support wrote:... Since most low bass content won't be panned much anyway, either solution will work.
This is a common myth that’s not quite right.
Being a recording engineer and music producer, without going into detail, I can assure that almost every recording contains significant amounts of stereo bass.
Using only one channel, some information is lost.Being a die-hard sub-bass fan with the matching equipment to analyse, listen and feel it, I disagree. It also makes no sense, as the lowest bass is not directional, so panning that frequency range would just lose volume/power in reproduction, but not bring any audible difference.
…
During music production bass sounds (I don’t mean the instrument itself) are not intentionally panned outside center TODAY.
But – a lot of stereo instruments contain frequencies at or below 80 Hz, the subwoofer range:
Keyboards and synthesizers, lower drums (like floor toms and the drum’s room mics), percussions, guitars, lower strings and ambient microphones to name a few.
These, of course are stereo or panned to a side to create a stereo mix.
During the mix there’s no regular separate access to the bass frequency range of those instruments.
To concentrate their bass frequenciy range to the center during mix and mastering, one would need to use a so called “Elliptical Filter” or “Elliptical EQ” (not to mix with elliptic- or cauer-filter topology).
That’s only done in some worst-case scenarios, as this filter audibly narrows the stereo width and reduces the ambient feeling (think “staging”).
This is for loudness-war pop- / rock-music, but there are other genres which are recorded much “purer”:
In old-school, now “audiophile” jazz, complete instrument groups are hard-panned left or right, eg. drum and bass left, piano right and only the solo instrument centered.
Then there’s classical music and film-score which is recorded with minimal manipulation.
Orchestral cello and double-bass is sitting to the right and their spot mics are panned accordingly.
The main, stereo mic picks the whole orchestra, depending on the mic-scheme used there’s a lot of stereo bass information.
A classical Tonmeister would never use any kind of such extreme processings like the mentioned “Elliptical Filter” unless hard-pressed with a gun on his head 
So, yes, bass in the subwoofer range in fact is stereo.
Using a mono-sub already is a compromise, but feeding it with just one channel (left or right), dropping the other, just for the sake of sparing one cable is ridiculous.
I learned a lot from all the expert comments, very much appreciate.
I decided to buy me a 2:1 mixer https://www.radialeng.com/product/mix-21/features, which allows me to implement what KaiS in fact initially proposed. This device has a Level Bypass Switch, to allow input 1 and input 2 (from the RME 2 Pro) to be summed up, and the convert to 1 output, equal to "volume" of the original source (input 1 or input 2).. The specs are really professional.
It will allow me to have the bass of the right and left channel summed up and converted to one output e.g. LFE.
I was, wrongly, under the impression that the 6.3 mm TRS ports on the back of the RME 2 Pro were each stereo, but that appears to be wrong: they are mono each, LEFT stereo en RIGHT stereo.
Sub Bass used to be panned during mixing of analogue recordings, but I have albums where the bass is NOT panned, hence I decided to go the way as described above.
A great many thanks to all your contributions to my fist posting.
You don't need that mixer, you just need two suitable cables, the subwoofer has a stereo input. LFE is just where you would plug a dedicated mono channel from some kind of 5.1 set of outputs or similar.
You don't need that mixer, you just need two suitable cables, the subwoofer has a stereo input. LFE is just where you would plug a dedicated mono channel from some kind of 5.1 set of outputs or similar.
+1 on that.
The sub has everything you need, including volume control.
RME Support wrote:You don't need that mixer, you just need two suitable cables, the subwoofer has a stereo input. LFE is just where you would plug a dedicated mono channel from some kind of 5.1 set of outputs or similar.
+1 on that.
The sub has everything you need, including volume control.
KaiS, I wasn't aware of the existence CINCH female/6.3mm Jack adapters. So, I ordered an identicai pair of adapters as shown in your above posting. Luckily I still had on stock a Y-Cable of 3 meters with CINCH Male connectors.
Conclusion: no need for a 2:1 mix device.
Thanks for your valuable input. Excellent.
You don't need the Y-cable.... Use a regular stereo cinch cable with the adapters.
You don't need the Y-cable.... Use a regular stereo cinch cable with the adapters.
As he already had the cable … works either way.
Yes, but everybody is likely to have a few spare RCA cables in "the box" as well (the one with all the unused accessories that have been waiting for decades to be used again...). Not sure how this subwoofer handles the LFE channel or whether it detects if only one cable is connected, but level matching may be easier in stereo. Also, I see people out there saying that Y-cables should only be used to split, not to sum signals... YMMV, it might just work fine here, and if no other cable is available, likely no harm trying.
… saying that Y-cables should only be used to split, not to sum signals...
That’s basically right, when linking amp outputs together, one amp loads the other with signal components that are not 100% the same - as you always find with stereo signals.
This can cause distortions or even breaking an output.
Never do that with speaker amp outputs!
The problem does NOT occur with ADI-2:
It’s combination of internal output resistors and OP-amp current capability prevents that.
All you get is a mono summing of output L+R, as intended.
I’ve tested that with a scope, otherwise I would not have proposed it.
As you might have noticed, the topic starter still insists there’s only one RCA input on his sub.
Maybe his sub’s model is really built that way, I can’t find a picture of version one’s Velodyne SPL-1200.
As you might have noticed, the topic starter still insists there’s only one RCA input on his sub.
Maybe his sub’s model is really built that way, I can’t find a picture of version one’s Velodyne SPL-1200.
I've seen pictures and the manual... There are definitely two inputs. Only one has a separate label saying LFE, for x.1 mono channels, which makes me suspect that perhaps the device detects if only one cable is connected and somehow adjusts levels differently. There are L/R labels, but only one each on top of a block of four RCA connectors for the inputs and outputs (you can pass signal through the subwoofer).
KaiS wrote:As you might have noticed, the topic starter still insists there’s only one RCA input on his sub.
Maybe his sub’s model is really built that way, I can’t find a picture of version one’s Velodyne SPL-1200.I've seen pictures and the manual... There are definitely two inputs. Only one has a separate label saying LFE, for x.1 mono channels, which makes me suspect that perhaps the device detects if only one cable is connected and somehow adjusts levels differently. There are L/R labels, but only one each on top of a block of four RCA connectors for the inputs and outputs (you can pass signal through the subwoofer).
There are SEEMINGLY indeed two RCA inputs, however the NON-LFE "RCA input" is closed with a tiny metal stop. I cannot even put a needle into it. No chance to force a CINCH male connector into it.
This discussion is time-wasting and pointless. Contact Velodyne support and ask if there ever was a SPL-1200 model that had one RCA input blocked. Online research suggests a broken tip of an RCA connector blocks your left input. Did you buy this one used?
Yes and yes.
Just so I'm not crazy... would connecting XLR outs to the 'main' speakers and then 1/4" outs to the subwoofer would cause a 3dB drop in level at the speakers (compared to only using XLR outs)?
Thanks!
Dustin
... would connecting XLR outs to the 'main' speakers and then 1/4" outs to the subwoofer would cause a 3dB drop in level at the speakers (compared to only using XLR outs)?
On ADI-2 DAC the RCA Output is 6 dB lower than the XLR, to better fit it into domestic levelled equipment.
On ADI-2 Pro and ADI-2/4 Pro SE XLR and Rear TRS carry the same level up to a reference level of +19 dBu.
For technical reasons TRS does not do the highest reference level step of +24 dBu, but stays on +19 dBu then.
There’s no 3 dB drop anywhere.
Anyway, it’s hard to define a “correct” level for the sub by looking at figures.
Every sub I know has an independent volume control that needs to be set by ear and/or measurement.
To add: XLR and TRS have their own driver circuits. You could short-circuit one of them, the other would still work undistorted at full volume. That is true for all ADI-2 Pro versions.
Also I went through the whole thread and replaced the highly confusing and wrong (!) 'RME DAC' with 'RME 2 Pro', to make this thread understandable for other readers.
dustin wrote:... would connecting XLR outs to the 'main' speakers and then 1/4" outs to the subwoofer would cause a 3dB drop in level at the speakers (compared to only using XLR outs)?
On ADI-2 DAC the RCA Output is 6 dB lower than the XLR, to better fit it into domestic levelled equipment.
On ADI-2 Pro and ADI-2/4 Pro SE XLR and Rear TRS carry the same level up to a reference level of +19 dBu.
For technical reasons TRS does not do the highest reference level step of +24 dBu, but stays on +19 dBu then.There’s no 3 dB drop anywhere.
Anyway, it’s hard to define a “correct” level for the sub by looking at figures.
Every sub I know has an independent volume control that needs to be set by ear and/or measurement.
Ahh ok that makes sense. Anecdotally, once I saw this post, I remove my home-built passive summing circuit for my subwoofer and connected it straight to the ADI-2 Pro with the 1/4" outputs while feeding my genelecs with the XLR outputs, and I thought my reference level of the speakers shifted 3dB (previous setup has 74dB SPL at -30dBr gain, new setup 74dB SPL at -27dBr gain)... but I had changed other things about my setup too, so the 3dB coincidence made me think of a possible shared (XLR+TRS) output at the RME All that said, the direct out to the sub is WAY better than my homebuilt summing circuit!
For Genelec’s main/sub combos connections I suggest to read their according manuals.
These guys did think about how to optimize things.
Mostly you would run the main stereo- (or multichannel-, in case) signal to the sub and feed the main speakers from there.
Depending on the main speakers’ size a high pass filter might come into play.
RME User Forum → ADI-2 & 2/4 Pro series, ADI-2 DAC series → 2 Pro connected to active Stereo Speakers. How to connect to Subwoofer
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