Subwoofer connections...what is great and what is not so good.

DaveyF · Nov 11, 2013

To follow up on the posts from the KEF LS50 thread, I thought a separate thread ( as Frantz suggested) would be a good idea.

The question is what is the best way to connect a sub to the main system. I am in favor of the REL protocol, which essentially allows one to connect the sub via a speakon cable directly to the amp speaker connectors. As Frantz correctly points out, the main amp sees a impedance from the sub that is very high and therefore should have no impact on said amp. The question, as far as I can see it, is does this perhaps compromise the main speaker's in some way, because the amp is still powering the mains and potentially overpowering them. I do NOT see this as an issue, BUT let's see the opinion of others here.

microstrip · Nov 11, 2013

From my limited experience the EQ facilities existing in most subs are not enough to allow the proper tuning of the sub to the system. Subs are usually considered as bass extenders and in practice most of the time they are working as fill-in or peak cancellation devices. This to say that IMHO the preferred method of connection will depend a lot on the system, room and sub being used.

Believe it on not, subwoofer setting is still black magic for 99% of the audiophiles, me included. Excluding the Earl Geddes method and the automatic JBL Synthesis system that Amir once referred, I have never read a set of decent rules that can be used by neophytes with success. I have tried several times using subs, and could get some very nice measurements, but it did not sound overall better than using just the main stereo speakers.

DaveyF · Nov 11, 2013

Micro, without doubt setting up a sub so that it compliments the main speakers and does not have any detrimental effects is by no means an easy task.
However, I do think not only is it possible, BUT with some general rules, it can be accomplished by anyone willing to take the time. This would certainly preclude anyone who thinks they can just plunk the sub down and it will be an instantaneous benefit.
( which almost all, if not all, subwoofer manufacturer's seem to make light of).
Since I am not an expert in subwoofer set-up, the following is all IMHO....BUT I have set up a fair number of these beasts and I think that the basics ( at least in my systems and rooms) have applied.
Firstly, I think the overall goal of how much bass is to be expected and required should be determined. Secondly, I think the basic room size and type/speed of the mains needs to be considered. Thirdly, I think the placement options need to be considered.
Then I think one needs to consider what is the smallest size driver one can get away with and still accomplish the bass re-enforcement that is expected or desired. ( NOT the largest driver that we can get away with...which is how I think most a'philes shop for a subwoofer, and which I think leads to more failure than any other factor).
Lastly, I think there needs to be some thought as to how much power and the type of power that the subwoofer of choice and the room size will dictate; plus the flexibility of how the sub connects and the type of options that it offers in said connection ( x-over slopes and volume controls etc).
BTW, i think we are all talking about subs for music production and NOT necessarily HT...as this could be a different discussion.

Like I said in the KEF thread, I happen to like the REL connection protocol, which takes the signal directly from the amp speaker terminals thereby guaranteeing that the mains see exactly the same signal as the sub.Others may differ here, BUT I happen to believe that this aspect also assists greatly in the set-up ease of the sub and likelihood of a true invisible blend between main and sub.

FrantzM · Nov 11, 2013

Davey

Excellent thread and subject. My experience differs from that of microstrip. When the time is taken to set up subs in a system , the results are better than those sans subs. This said, allow me to re-make a somewhat sweeping statement: In my experience, limited output speakers won't magically be transformed into large speakers-beaters in term of scale and bass dynamic by the addition of subs. Minimonitors tend to continue to sound like that even with the aidditon of sub.

I would venture that REL method is a clever marketing ploy directed toward us the audiophiles. Taking the signal from the amps is not in any way superior to taking it from the preamp. The notion of amp flavor is a false one that cottons, again to our sensibilities. If however we don't want to make our system complicated it is a good way, simply use a cable from the mains to the subs .. Again many if not most subwoofers allow this type of connection.

As for driver size let's drop the big drivers = slow bass ... and small drivers = fast bass ... The more we continue to repeat these the less progress we will make in reproducing good bass in our living roo. I will quickly add that the notion of overloading the room because the woofer is too powerful is another falsity , if it is too loud, you reduce the volume. As simple as that!

Oh I believe EQ, epcially the outside variety is a necessity in the lows.

Working very hard these few days .. Will continue my thoughts on this later

DonH50 · Nov 11, 2013

I prefer to split the preamp output and avoid any possible amp/speaker interactions that corrupt the response of the sub.

My Rythmik subs include phase and single-band PEQ built-in that helps with system integration. Other high-end subs include extensive processing capabilities.

DaveyF · Nov 11, 2013

Frantz, I'm not saying that BIG drivers are necessarily slow or that small drivers are fast. (although physics would dictate that the ability to accelerate quickly is related to the mass that has to be moved). OTOH, I am stating that the larger the driver, the more air it is going to be able to move and therefore the more likely to overload the smaller room. I do NOT agree with you that simply turning down the sub output to reduce volume is the solution to overloading the room. Lets take this example: ( albeit extreme) we place a 21" bass driver in a large enclosure in a 10x10 room....that volume had better be VERY low for it to not overload that room. OTOH, we place a 4" bass driver in the same size enclosure ( yes, I know there aren't many of these) in the same room....get my point.

microstrip · Nov 11, 2013

FrantzM said:
(...) I would venture that REL method is a clever marketing ploy directed toward us the audiophiles. (...)

Frantz,

IMHO no, it is not. This method is mainly included in cheap subs to allow them to be used in stereo systems using receivers that lack a preamplifier output or preamplifiers that do not have double outputs or are not able to drive the subs low impedance load. BTW, as far as I know most audiophiles do not use it - some even prefer to use tube buffers to drive the subs!

Do you have any recipe book for setting subs?

rbbert · Nov 11, 2013

I think the type of connection is relatively insignificant compared to the physical placement of the sub and the specifics of the crossover.

DaveyF · Nov 11, 2013

rbbert said:
I think the type of connection is relatively insignificant compared to the physical placement of the sub and the specifics of the crossover.

Agreed. Although there are the other points that I stated above that I think are highly important.

JackD201 · Nov 12, 2013

In my experience, if you are crossing over above 55Hz go with the high level inputs as the sub should take on some of the main amps characteristics, anything below stick to line level. Interconnects are cheaper than speaker wire and less likely to cause shorts if the cables are accidentally yanked, pulled or tripped over.

DaveyF · Nov 12, 2013

Jack, why do think that line level is better if one is crossing over below 55hz? Which would mean that the main amp characteristics would not be passed through. IMO, the ability of the sub to see the same amp characteristics as the mains and vice versa is a major plus.

JackD201 · Nov 12, 2013

I said the main amp characteristics may/will be passed through not the opposite. I find this important because we are still sensitive to some timbres above 55Hz. That isn't , at least for me, the case below it. The sub is doing mostly long tailed decays at that point because the transients they are following behind are happening even for kicks and tympanies way above that range. I'll always go for the cheaper, safer connection when it is at a point where I no longer hear any real difference.

So say for a monitor, I would use the high level input since typically I set a rather flat slope that begins where bass response begins to drop off. I don't wait for the monitors to drop even 2dB much less wait for mechanical roll off. This is typically in the 60s or 70's and in some cases even in the 80s.

Drikus · Nov 12, 2013

DaveyF said:
To follow up on the posts from the KEF LS50 thread, I thought a separate thread ( as Frantz suggested) would be a good idea.

The question is what is the best way to connect a sub to the main system. I am in favor of the REL protocol, which essentially allows one to connect the sub via a speakon cable directly to the amp speaker connectors. As Frantz correctly points out, the main amp sees a impedance from the sub that is very high and therefore should have no impact on said amp. The question, as far as I can see it, is does this perhaps compromise the main speaker's in some way, because the amp is still powering the mains and potentially overpowering them. I do NOT see this as an issue, BUT let's see the opinion of others here.

I've got Rel G1 and connected the sub on first installment via a speakon cable directly to the amp speaker connectors and that resulted in a huge hum comming from the sub that I couldn't get rid of no matter what I tried. Using interconnects from pre to sub, hum was gone.

DaveyF · Nov 12, 2013

Lindeman said:
I've got Rel G1 and connected the sub on first installment via a speakon cable directly to the amp speaker connectors and that resulted in a huge hum comming from the sub that I couldn't get rid of no matter what I tried. Using interconnects from pre to sub, hum was gone.

Sounds like EITHER you are not correctly grounding the cable at the amp end, OR there was a problem with the grounding at the speakon connector. I would certainly talk to your dealer about this problem as it is not normal.

microstrip · Nov 12, 2013

DaveyF said:
Is that supposed to be funny, because I'm not laughing.
"This method is mainly used in cheap subs".....really, so the REL's are cheap subs?

Davey,

OUF! My apologies, I said mainly only because cheap subs outnumber audiophile subs by a large margin and almost all of them use this system. I know REL are high quality, I have owned a few of the smaller ones and even considered them for the Aida's sometime ago, as the US importer demoed them with four G1's and uses and sells REL subs. Are you smiling now?

Drikus · Nov 12, 2013

DaveyF said:
Sounds like EITHER you are not correctly grounding the cable at the amp end, OR there was a problem with the grounding at the speakon connector. I would certainly talk to your dealer about this problem as it is not normal.

Like I said, I tried EVERYTHING with the speakon connector. The way it's connected now is just fine for me

DaveyF · Nov 12, 2013

Lindeman said:
Like I said, I tried EVERYTHING with the speakon connector. The way it's connected now is just fine for me

That's great

. BUT you seem to be implying that the speakon connection and the amp/sub connection method is inferior. Which, I believe IF you were able to set up your sub with that method, you would find the
opposite. Simply because your connector is faulty OR you have not connected the cable correctly at the amp end ( no grounding) doesn't invalidate the set up. BTW, IF you amp is balanced, ( I have an ARC tube amp
that is set up this way...) the connection is NOT the same as suggested in the sub manual. You would again need to talk to Sumiko or the amp manufacturer for their set up recommendation. ( It is VERY odd that
the manual for these subwoofers mentions NOTHING about this issue

).

Drikus · Nov 12, 2013

DaveyF said:
That's great. BUT you seem to be implying that the speakon connection and the amp/sub connection method is inferior. Which, I believe IF you were able to set up your sub with that method, you would find the
opposite. Simply because your connector is faulty OR you have not connected the cable correctly at the amp end ( no grounding) doesn't invalidate the set up. BTW, IF you amp is balanced, ( I have an ARC tube amp
that is set up this way...) the connection is NOT the same as suggested in the sub manual. You would again need to talk to Sumiko or the amp manufacturer for their set up recommendation. ( It is VERY odd that
the manual for these subwoofers mentions NOTHING about this issue).

???I'm NOT implying ANYTHING, I just told you what I did, if the hum hadn't been there, I would have use THAT connection, that's ALL...Yes, my amp is fully balanced, a Lindemann 858.
So YOU compared the two DIFFERENT connections?

DaveyF · Nov 12, 2013

Lindeman said:
???I'm NOT implying ANYTHING, I just told you what I did, if the hum hadn't been there, I would have use THAT connection, that's ALL...
So YOU compared the two DIFFERENT connections?

Fair enough...BTW, I'm NOT trying to get you upset, I'm simply trying to stipulate that more than likely there is something wrong with your speakon cable connector OR how you set up
the connection at the amp end ( the grounding protocol due to your amp being fully balanced, which is what I suspect causes the problem). Period.

I have listened both ways, and to me, the sound is better with the sub seeing the same signal as the mains from the amp.( which is the way that REL suggest the connection be made if at all possible....for the same reasons). YMMV.

Drikus · Nov 12, 2013

DaveyF said:
Fair enough...BTW, I'm NOT trying to get you upset, I'm simply trying to stipulate that more than likely there is something wrong with your speakon cable connector OR how you set up
the connection at the amp end ( the grounding protocol due to your amp being fully balanced, which is what I suspect causes the problem). Period.

I have listened both ways, and to me, the sound is better with the sub seeing the same signal as the mains from the amp.( which is the way that REL suggest the connection be made if at all possible....for the same reasons). YMMV.

Ok, I've sent a mail to Sumiko. I'll see what they say.

Subwoofer connections...what is great and what is not so good.

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