Good morning @Dan_M. As you will know, i have a pair of Sopra N2’s as well. This thread has had my full attention since your first post lol. I am now very very seriously looking at adding an 812 to my system. In fact i have found a pre-loved one for £1700. At the moment though i can only afford the one, my question is , would i hear a significant difference from just one ? Or are two really the only way to go ?
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One is a big difference. I was going to stick at one and add a 2nd later down the line. But because they stopped production I got the 2nd.
2 sounds better but one is good enough.
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Buy button pressed and paid for now. Will have it next Sunday 
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I got a bit sucked in by guys on here saying 2. But one is really good enough. Yeah sure 2 is better but alot more dough! 
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For those interested Paul McGowen from PS Audio has a very good youtube video on how to set up the crossover on subwoofers. He discusses that he frequently gets emails from people saying they are dissatisfied with the integration of the subwoofer, and when he goes to investigate he finds they have set it up totally wrong. In particular the crossover is way too high. He advocates an approach where you turn the crossover all the way down and then get the volume correct by trying different settings until you feel the loudness of the deep base is at similar level to other instruments. Then you listen to a male with a deep voice singing and raise the crossover until you start to hear more chestiness in the voice but stop and slowly reduce when the subwoofer becomes evident. The crossover setting using this approach is usually very low.
i did not use this approach myself but my settings are very low on the crossover. On the Rel 510 with Quad 2805s i usually run the crossover at 1-2 clicks, and the volume at 4-6 clicks. Right now i am at 1/5, but sometimes play with it in those ranges. I would expect dynamic speakers to go higher on the crossover.
the video is named “how subwoofers ruin midrange clarity” and was just published on youtube 6 days ago.
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Hi Dan, if one is really good enough I might be tempted to try one once my speakers have arrived/bedded in. Rel recommend 2x T5x for the SCM20asl but my dealer reckons nothing less than the t9x. A t9x is less than a grand used / exdem so worth a punt in my book. If all goes well then another used next year maybe. If I go down this route I’ll definitely try some Russian Techno in your honour 
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Glad you’re enjoying some of the benefits of a subwoofer reproducing sub bass frequencies 
Btw, your system can benefit further by unburdening frequencies up to around 90Hz. All things being equal this should result in a profound uplift in using the subs so far for music 
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Do you mean setting the crossover that high?
This is exactly the method the rep from REL walked me through for set up. I also had the crossover set too high and the gain too low. After setting it up the opposite, crossover low, gain higher my pair of T/X9 REL subs sound very well integrated with my ProAc D2R speakers.
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Yes it seems like the best way by far to get the settings right.
Proacs with the Rel subwoofers must be a terrific combo…always liked Proacs. Enjoy!
In the video Paul says that sometimes the crossover should be left at zero. That’s how i had it in my old house in a very small basement listening room. In the new house the room has more volume so i put the crossover at 1 click. Gets a very slight uptick in body without trashing the Quad sound in any way.
Yes however if your electronics haven’t got low-pass filter and high-pass filter then you’ll need to use an active crossover.
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Got it. Thanks.
So the intention is to overlap the bass frequencies rather than the sub taking over at exactly the point the main speakers bass rolls off? Might explain why many people find it fiddly to dial their subs in. Everyday is a school day 
In Paul McGowens video that i referenced he says that the idea of setting the crossover at the exact point where your speaker range ends (say 50hz) is “logical” but never ever works. The crossover should be set much lower, even at zero in some cases. The approach he suggests is a very good one to make sure your crossover isn’t high enough to start intruding on your speakers midrange and trashing the overall sound quality.
let’s put it this way…if you are “blown away” by your subwoofer than almost for sure the crossover is set way to high. If integrated correctly you should have lower fuller bass without even being able to detect the subwoofer.
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You’re welcome
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On the contrary. My opening post clearly states “UNBURDENING frequencies up to around 90Hz.” This is as I subsequently said in my second post is achieved by using a crossover if available within the electronics or the use of an external active crossover.
Btw, over the years I have set up many systems with subs and I have yet to come across a phase setting where O degrees or 180 degrees has been the optimum.
Anyway, in my experience mains and sub/s have to effectively aligned, calibrated and dialled in. Get this right and there is seamless integration. Only then does the system click into place.
I’ll leave it to experts in that case
There doesn’t seem to be a conclusive way of doing things with dialling in subs. And with Rel’s what do the different clicks mean? What does 9’oclock mean or 12 o’clock? I have gain set at 12 o’clock and crossover set to 9 o’clock.
I am not a sound engineer. I have set them up and am enjoying the experience. I have set them up to how I like the sound.
And of course it is subjective surely. If you like bass and listen to techno and drum n bass you want the gain higher than someone who likes jazz and classical musical. If the gain is too high my ears literally hurt
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An electric 4 string bass guitar in a pop/rock band is generally tuned to 41Hz, as is a double bass in a Jazz band.
A modern classical orchestra generally can go down to 32Hz.
Electronic music/synthesiser music can easily go down to 20Hz, the general human hearing lower frequency response.
I will probably be reducing my subwoofer crossover frequency down from 45Hz to 40Hz to make that comparison to see if that sounds better, thus a better integration with my main speakers that go down to 33Hz.
From what Ive read online and from my listening tests so far setting the subwoofer crossover frequency too high will be detrimental to the bass and mid-bass performance of the main speakers and thus the resultant overall sound quality for stereo music will be compromised and sound worse, which is my in home listening experience so far.
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When I was Bass player in a band, I asked if my Bass could be fed thru the mixing desk rather than relying on my amp in larger venues. I was told no because the Bass signal would modulate the other signals. Is that really a thing?
I think it is more likely that I just wasn’t that good 
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