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High level speaker amp out to RCA

Hello community.

Many preach, including REL,  that the best way to connect a subwoofer is from the high level speaker output from the amplifiers so the sub receives the same "signature" sound the amp sends to the speakers. This sounds quite logical!! My subs only have RCA inputs, how can I go about this type of connection? Is there a good high level to RCA thingamajig?? Any suggestions??

 

Thank you for your constant guidance!!


128x128carlosr
9 responses Add your response
bdp24's avatar
bdp24
9,816 posts
 

High-level power amp output hookup to a sub being superior to line-level hookup is a debatable contention. Brian Ding, designer and maker of the Rythmik Audio subs, provides both on his models which contain either the A370 or H600 (non-XLR version only) plate amp. It is his opinion that high-level hookup is preferable.

Why would anyone want to add the distortion all power amps produce to the signal sent to the sub? People say a sub hooked up high-level is more apt to sound like the speaker hooked up to the same amp, which is to admit that the power amp is not transparent. The better the amp, the more the high-level hookup will sound like the line-level hookup, right?

roberjerman
4,319 posts
 
Use a pair of rca y-connectors and a long rca interconnect from your preamp. Avoid the amp-to-sub method. NG! That is what I do!
carlosr's avatar
carlosr OP
5 posts
 
I have read many conflicting opinions on this topic, and the point you raise about introducing the amp distortion to the sub signal is very logical.bdp24 

I am having some issues with my RCA connection from my preamp. I hear the sub "interacting" with the speakers.  Sometimes it makes a clicking sound, other times there is a little click sound when I use the volume on the remote, up or down. Sometimes just straight interference sound, very rarely though.

My preamp is a Sunfire Vacuum Tube Controller, it has 2 parallel main out RCA style, and one XLR.  My amp, a Sunfire 300 Two, is connected with the XLR.  My sub/s, tried with single and dual, are connected using the parallel main out posts from the preamp.  The main idea was to go straight to the amp because apparently the Preamp is getting this interference. Just trying something new!!
bdp24's avatar
bdp24
9,816 posts
 
Oops, the last sentence of my first paragraph above reads "It is his opinion (referring to Ryrhmik designer Brian Ding) that high-level hookup is preferable." I meant to say line-level (pre-amp), not high.
erik_squires
16,118 posts
 
You would need a new buffer circuit or a voltage divider. Assuming the inputs are high impedance (25k or higher) I'd suggest you try 100K in series and then 1k to 5k in parallel. This would give you 1 to 5% of the amplifier output at the sub inputs. You could also use a pot instead of the small value resistor. 

Be careful as you certainly can provide too much voltage to the line in and damage it, so use a voltage meter at the small resistor to make sure you stay below 2V 
carlosr's avatar
carlosr OP
5 posts
 
Seems like its not that straight forward.  I there an external adapter/converter that is just plug and play??
birdfan's avatar
birdfan
175 posts
 
I recently purchased a new(used ) tube preamp. It does not come with extra set of 'outs' for a subwoofer connection. My subs are RCA level input only, so I am in the exact same predicament. 

I have a friend who designs some of the world's best loudspeakers who, taking pity on me, has agreed to put together the right package of resistors to make my speaker level connection into a line level with some spare speaker cable, some resistors in series and and soldered RCA plugs. 

Its not done yet but I can hit you back with the design and reports of how it works when I get them. 

.. More to come. 
imhififan's avatar
imhififan
2,203 posts
 
Is there an external adapter/converter that is just plug and play??

It is a voltage divider that erik_squires referring to:

https://www.crutchfield.com/p_543ADP12/Russound-ADP-1-2-Speaker-level-to-Line-level-Adapter.html?tp=...
attenuation: -30 dB, should be safe to connect to your subwoofer.
carlosr's avatar
carlosr OP
5 posts
 
Its not done yet but I can hit you back with the design and reports of how it works when I get them.

.. More to come.


Thank you, greatly appreciated!!


It is a voltage divider that erik_squires referring to:

https://www.crutchfield.com/p_543ADP12/Russound-ADP-1-2-Speaker-level-to-Line-level-Adapter.html?tp=...
attenuation: -30 dB, should be safe to connect to your subwoofer.

Thanks, will try this out and see how it goes!!

Thank you all for your help!!

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