Anyone using high level inputs on sub?

[Jgw911]

Hi all

Has anyone got a subwoofer connected to their Dev via high level inputs?

I’ve recently bought a new sub and connected it using this method and it sounds great. But then I read this:
https://rel.net/connect-rel-class-d-gear/

Now I’m worrried

Are Devialet amps among the 90% where the black speaker terminals aren’t a true ground? Know these are hybrid class AD but not sure what that means for the speaker terminals.

Does anyone know?

[Pim]

Definitely question for Devialet to answer. My question to you is, do you use SAM? I've often wondered how SAM would impact the use of high level input on REL subs.

[Jgw911]

Thanks Pim. Yes, maybe I should drop Devialet an email.

I’ve got SAM turned on but dialled back to zero. It didn’t sound very good with SAM at anything above 50%, and I figured it’s probably best to reduce it to zero.

[ogs]

@Jgw911 I do not think SAM should be on when you connect a sub to the speaker outputs. You'll get the SAM correction made for your main speakers applied to the subwoofer too. I do not think it is dangerous, but it will not sound right.
For your original question let us also ping @yabaVR. He has intimate knowledge of the D200 speaker output wiring after modding his own amp.

[David A]

I'd ask Devialet about the appropriate connection method but I think SAM **MAY** have some slight benefit in conjunction with a REL.

If you're using the high level input to the REL you're running your main speakers full range so SAM may help with them. The idea when using the high level input to the REL is that you run the main speakers full range and select your crossover and level on the REL so that the REL rolls off as the mains are rolling off and the sound from the REL as it rolls off adds to the sound from the mains as they roll off to produce a smooth bass response. Yes, the REL will be getting the same correction as the mains and the phase correction provided for the mains may not match the ideal phase correction for the REL but it **MAY** help in producing a smoother blend with the mains in the crossover region. A lot is going to depend on the response of the REL in the crossover region and how it blends with the mains as they roll off.

2 important points:

First, REL state that the main mistake people make when integrating a REL with the main speakers using the high level input is setting the crossover too high and the REL's gain setting too low. What I found when using the high level connection in a home theatre setup (not with a Devialet so no SAM) was that I needed to set the crossover frequency on the REL to the lowest frequency possible when pairing with a pair of Dynaudio Contour 1.3 SEs (2 way standmount monitor) which surprised me so I'd start with the lowest crossover frequency setting and start raising the gain to try and achieve a match.

Second, I've used my 130 PRO first with the same Dyn 1.3 SEs and also now with a pair of Sopra 2s, neither with a sub. I've found my best results come when setting SAM low, usually around 25% or lower and felt that things didn't sound good if I set it higher. I've never been happy with SAM at 50% with either of my speakers so I'm not surprised to hear that you don't thing it sounded very good with SAM at anything over 50%. I'd suspect, given that the SAM profile for your mains is unlikely to be a perfect match for your REL, that if SAM is going to be of benefit with the REL you would need to set the SAM level low, perhaps even at 0%. I'd also think that finding the right phase setting, zero or 180 degrees, may make a difference as well.

REL make a number of different sub models and your results may well vary depending on which model REL you use since the SAM profile for your mains may be closer to some REL models than to others.

I think it's worth a try but it may or may not work. If you want to get more bass extension from your mains you may well be better off trying some bass traps to improve your room's bass response and SAM may help there as well. Once again I'd think you'd need to use a very low crossover frequency and careful adjustment of the gain setting, and you'd probably do better with a low SAM setting. My room has bass traps which do help with my bass response, both with or without SAM, and the bass traps may well be part of the reason why I find myself preferring a lower SAM setting.

So, provided there are no problems with the grounding side of the connection, I'd say it's worth a try with the REL but there's no guarantee that the REL will be beneficial.

[Jgw911]

Wow, thanks all for the great and helpful responses.

Have tried using SAM at 0% versus SAM off completely and can't honestly tell the difference so have left it at SAM 0% (so I don’t have to go to the effort of creating another configuration file.

Regarding the crossover frequency and gain - great points. I’ve already played around with that. 40hz didn't sound very integrated and 120 seemed too ‘full’ sounding in the lower end of the sound spectrum (if that makes sense). To my ears 60 to 80hz sounded about right so have left it at 80.

Bass traps aren’t really an option for me (wife is pretty tolerant but she would definitely draw the line at having those in the lounge). Have tried a number of speakers with more powerful bass but I couldn’t ever get them to work in the room. Having the sub to augment the speakers seems to be working better than anything else I’ve tried so far, and I haven’t even been using a sub EQ system yet).

In fact (pardon the pun) I’ve been finding my current floorstanders a bit harsh in the treble recently. Use of a sub might encourage me to take a look at some nice standmounts to replace my FACT8’s.

Anyway, have emailed Devialet about the grounding on the speaker terminals so will see what they come back with.

[JohnnySix]

Wow, thanks all for the great and helpful responses.

Have tried using SAM at 0% versus SAM off completely and can't honestly tell the difference so have left it at SAM 0% (so I don’t have to go to the effort of creating another configuration file.

Regarding the crossover frequency and gain - great points. I’ve already played around with that. 40hz didn't sound very integrated and 120 seemed too ‘full’ sounding in the lower end of the sound spectrum (if that makes sense). To my ears 60 to 80hz sounded about right so have left it at 80.

Bass traps aren’t really an option for me (wife is pretty tolerant but she would definitely draw the line at having those in the lounge). Have tried a number of speakers with more powerful bass but I couldn’t ever get them to work in the room. Having the sub to augment the speakers seems to be working better than anything else I’ve tried so far, and I haven’t even been using a sub EQ system yet).

In fact (pardon the pun) I’ve been finding my current floorstanders a bit harsh in the treble recently. Use of a sub might encourage me to take a look at some nice standmounts to replace my FACT8’s.

Anyway, have emailed Devialet about the grounding on the speaker terminals so will see what they come back with.

I used the High Level inputs to my REL T2 for several months in the early days of my D120 (before my speakers were SAMmed) and it was fine.
Not like with my Rotel Class-D multichannel amp, which produced a scary groan out of the REL!
(The Rotel had "Lightning" symbols on all the speaker outputs to warn against this)

[Jgw911]

Thanks for this @JohnnySix.

Still no response from Devialet, apart from telling me they love me (auto email response). Always nice to hear I guess. Think they are now beyond their “24 business hours” for a response - even French business hours ;-)

Maybe they are having trouble translating that REL web article.

[Jgw911]

Just to complete this thread, for anyone searching for this information in future - Devialet support finally got back to me after almost one month to say that their black speaker terminals are at true ground so I can connect my high level sub wires as with any normal (class A or AB) amp.

Absolutely loving my sub connected in this way. Thought that PMC Fact 8s were full range but this adds a whole new dimension to my musical enjoyment. The biggest surprise is what it adds to classical music.

Happy days

[chrisc]

I measured the speaker ground and it is tied to system ground

Btw, if a sub-board became available for sale, I would be interested. These seem to be about $500 new which is more than I want to spend