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Answered Connecting speakers to SUB output

BarKohba

Active Member
Hello,

I was wondering, some subs, including the one I have (yamaha sw700) have speaker outputs on them (which work shen the sub is connected to the receiver at speaker output).

As some recievers/amps dont have 2 dedicated sub outputs (only mono), the only way to connect 2 subs is at rhe speaker outputs. However, in order to then low cut the main speakers, the only way to achieve that is to connect the main speakers to the sub speaker outputs - this way i can control the low crossover from the sub and prevent frequency overlap and overworking the mains (especially when we re talking about bookshelves).

My question is: what are the disadvantages of connecting the speakers this way? Since the signal from the amp first goes to the sub, and then routes to the main speakers (sans the crossover frequency range), is there any sound degradation for the speakers vs a direct connection to the amp?
 

BarKohba

Active Member
Just to add more context, this is how I could connect my sub to my receiver:
1.PNG


However, with this type of connection, I have no way to low-cut the speakers, only the subs. If I want to have the ability to low cut the speakers, I have to connect them to the speaker output connections on the sub like so:

upload_2019-2-22_18-49-46.png

However, since in this scenario, the speakers take a "longer" route to get the signal: receiver -> sub -> 80hz crossover to sub -> 80hz and above from sub to speaker, is this a disadvantage when it comes to sound quality, is the speaker signal affected vs a direct connetion to the receiver?
 

Ugg10

Distinguished Member
Some subs use the speaker level throughput to carry out the crossover function i.e. full range goes into the sub through the speaker cables, inside the sub it is then filters the signal and only outputs the frequencies above the crossover point (typically 50-80hz).

In AV system this is typically done in the receiver/amp.

It also alows the sub to be used with amps that do not have a sub or pre-out connectors.
 

John7

Well-known Member
In your case, you should connect your speakers direct to the receiver and the subs by the LFE dedicated output. This way, the receiver will be able to apply the correct Bass management. If you connect via the speakers, the Receiver's bass management is prevented and you are relying on the Sub's crossover which is not proper bass management, just a high pass.

If you have 2 x Sub's and a receiver with one LFE line out, you can get a "Y" splitter to send the signal to both sub's.
 

BarKohba

Active Member
Some subs use the speaker level throughput to carry out the crossover function i.e. full range goes into the sub through the speaker cables, inside the sub it is then filters the signal and only outputs the frequencies above the crossover point (typically 50-80hz).

In AV system this is typically done in the receiver/amp.

It also alows the sub to be used with amps that do not have a sub or pre-out connectors.

I understand that, but considering that my receivers applies crossover and low cut settings to the sub/speakers only when using 1 sub connected to the sub dedicated connection, connecting the speakers to the sub is the only way i can use 2 subs with low cutting the speakers.

However what im wondering is whtlether this has any negative on the sq coming from the speakers (compared to how the speakers sound connected directly yo the receiver)
 

Ugg10

Distinguished Member
The sub out on the amp will be a summed left and right signal, if you used the speaker posts on the sub then the sub would do the summing. But as @John7 says, if the sub has a built in crossover on the speaker connections this will just get confusing with the amp also doing bass management.

Typically if the amp has bass management/crossover built in (as your has) then use the sub out rca/coax connection, the sub is set to crossover at the max frequency (100-140hz) and the volume set to about half-two thirds (if that is too loud turn it down), then let the amp sort it out.
 

BarKohba

Active Member
In your case, you should connect your speakers direct to the receiver and the subs by the LFE dedicated output. This way, the receiver will be able to apply the correct Bass management. If you connect via the speakers, the Receiver's bass management is prevented and you are relying on the Sub's crossover which is not proper bass management, just a high pass.

If you have 2 x Sub's and a receiver with one LFE line out, you can get a "Y" splitter to send the signal to both sub's.

Goddamn, that makes so much sense I can't believe I never thought about searching if such a Y splitter exists. Just researched a bit online and Audioholics also recommend the same thing.

Great answer! thanks! this basically solves my issue completely, and now I can still rely on my Yamaha receiver's YPAO (DSP room correction).
 

BlueWizard

Distinguished Member
I'm most leaning toward John7's statement.

Using the Speaker Level connections would give you Stereo Subs, assuming you have TWO Subs. But with only one Sub, whether you use the RCA Line Level In or the Speaker Level In, inside the single Sub, everything is converted to Mono.

Now with two Subs using Speaker Level connections, you could technically have one Right Sub and one Left Sub, but low bass even in Stereo still sounds Mono, so unless it is a pure music only system, there really is no advantage to Stereo L/R Subs.

A Single "Sub Out/LFE" on a AV Receiver can very likely still drive TWO Subs, you just need a "Y"-Splitter Cable to break one line out into two.

For Music or a Music System, which does not have LFE, Speaker Terminals might be fine. But in an AV Surround System, you only truly get the LFE (low frequency effects) channel from the LFE/Sub output. So in a movie system, you absolutely want to use the LFE/Sub out on the AV Receiver.

Essentially saying what John7 said, but hopefully confirming his statement.

Steve/bluewizard
 

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