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PostPosted: Sun Apr 15, 2018 8:04 am 
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My pre-amp has only one volume controlled output and my sub doesn't not have an option to connect via speaker cables, only RCA line level. Am I better splitting the signal at the pre-amp output or the amp input ports? Does it matter? Is there another option?
Much appreciated!
V


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PostPosted: Sun Apr 15, 2018 8:41 am 
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Hi,

If you have a separate pre-amp - then split using the pre-amp (to amp) outs. The volume control on the pre will feed the sub a proportional signal. You can then also set the volume control on the sub to get the balance you like.

Another option is to feed the sub with the 'tape out' signal from the pre-amp and no splitter is required. But that signal is a 'line level' signal and is not controlled by the volume control and so you will need to set the volume control on the sub to work for you at whatever levels you normally listen. When you turn down the volume on your pre-amp, the sub will still offer the same level as before and this will add bass and low mid-range 'presence' to the mix. Older recieivers and amps used to have a 'presence' switch that did this for you on a non-sub system.

Try to keep the sub volume low. It's purpose is to support the low bass and not shake the room. The cross-over setting on the sub should also be kept low - under 100KH if possible, and 80 is even better.

Cheers,
David Neice

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PostPosted: Sun Apr 15, 2018 9:00 am 
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Respectfully, I've got to totally disagree with Buybye88's tape monitor out suggestion. A fixed line level out is not at all appropriate.

Buybye88's first suggestion was the correct one. VegliaAudio, provided that your preamp's output impedance is sufficiently low and the input impedance of both your power amp and subwoofer line level input are high enough (ideally power & subwoofer amp input impedance is at least 10X that of preamp output impedance), a simple Y connector/splitter arrangement from the preamp will get the job done.

Where is your subwoofer(s) located in relationship to your pre and power amps VegliaAudio? Depending on your setup, I may be able to help out with the Y-splitter cables. My prior subs had single-ended RCA inputs for which I commissioned Gene over at Take5 audio to make me some sweet custom Belden splitter cables with Vampire RCAs. If the lengths prove useful you can have them for cheap. Feel free to PM me.

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PostPosted: Sun Apr 15, 2018 9:06 am 
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Ya, tape output is a no-no.
Unless you want to run back and forth adjusting levels and such, etc, etc.

Split it, as prior mentioned, at the outputs as close to the pre-amp as you can. More cabling, dispite minimal effect, increases impedance...why bother doing that.

Good luck.


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PostPosted: Sun Apr 15, 2018 9:08 am 
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Thanks for the replies. The only question I have is "Am I better splitting the signal at the pre-amp output or the amp input ports?"
That's all ...
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PostPosted: Sun Apr 15, 2018 9:31 am 
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Like they all said, at the pre-amp. Never heard of the option you present.
And am pretty sure if you split the signal at the sub-, this will not work well or at all; no 'mechanism' for the signal to flow back to the power amp.


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PostPosted: Sun Apr 15, 2018 9:31 am 
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It doesn't really matter- though depending on the splitter device, the preamp end may be more practical.

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PostPosted: Sun Apr 15, 2018 9:54 am 
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Hi,

VegliaAudio wrote: 'Am I better splitting the signal at the pre-amp output or the amp input ports.'

I guess I don't understand this at all. Either way the impedance is additive.

Here's a reply to all those smarty-pants who think you shouldn't use 'tape out' to run a sub. Normally, listeners have just two preferred volume settings, 'background' and 'paying attention'. If you set the sub up to work maximally at the 'paying attention' volume level and set the X-over and phase for that, then when you turn the amp down to 'background' level you will get a presence boost. Lots of integrated amps without a pre-out function can get sub support this way. It's not perfect, but then nothing ever is in audio.

Cheers,
David Neiice

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PostPosted: Sun Apr 15, 2018 11:15 am 
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buybye88 wrote:
VegliaAudio wrote: 'Am I better splitting the signal at the pre-amp output or the amp input ports.'
I guess I don't understand this at all. Either way the impedance is additive.

David, splitting at the preamp output means getting a Y type splitter and than running 2 separate RCA cables, one to the amp, the other to the sub. Splitting at amp end would mean a piggyback type connection at the amp. So, I would run a single set of RCA cables from pre to the amp, then at the amp input RCA ports I'd have this piggyback type splitters so that the signal flows both to the amp and to the sub via another separate cable. I'm thinking it's probably the same. In my case splitting at the amp end is just easier, space wise. That's all. But all the applications I've seen in the past have the splitter at preamp side, so you wanted the CAM community to opine on the other option to make sure I'm not missing something.
Thanks
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PostPosted: Sun Apr 15, 2018 11:24 am 
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VegliaAudio wrote:
My pre-amp has only one volume controlled output and my sub doesn't not have an option to connect via speaker cables, only RCA line level. Am I better splitting the signal at the pre-amp output or the amp input ports? Does it matter? Is there another option?
Much appreciated!
V


Split the signal at the preamp out. Use a good y-cable or RCA piggy-back jumpers.
https://www.aliexpress.com/item/1pc-RCA ... 66614.html


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PostPosted: Sun Apr 15, 2018 1:00 pm 
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MTB Vince wrote:
Respectfully, I've got to totally disagree with Buybye88's tape monitor out suggestion. A fixed line level out is not at all appropriate
Well, I disagree with you MTB Vince if the sub has a level input volume.

Tape out of the preamp is direct from the source. No loudness or bass/treble amplification.
With preout, crossover or not, if he's using loudness or bass button, this will affect both normal speakers and the sub.
Then, some bass frequencies will be boosted inequally. Even worst, those frequencies are very likely the frequencies (60-120hz)
where the room acoustic is sensitive. Boominess assured...

From tape out, better sound but not practical.
From preout, only one volume button.

Just test both possibilities, Veglia.

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PostPosted: Sun Apr 15, 2018 1:38 pm 
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Many have different volume settings as per the music they listen to. Same can be said about background music. Using the tape out, one will be constantly adjusting the sub volume. Royal PIA!

As for tone controls with the preout. These can be turned off and even used if preferred. Non issue.

What is the subwoofer in discussion? Some employ an filtered line level out to connect to your amplifier. The splitter may not even be required.


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PostPosted: Sun Apr 15, 2018 1:41 pm 
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Just make a speaker to line adapter . Or purchase one from an automotive installer .Or use one like this .https://www.russound.com/products/audio-systems/multi-room-controllers/expansion-devices/adp-1-2-speaker-to-line-level-adapter or this https://www.ebay.com/itm/12V-RCA-Car-Radio-Stero-Converter-Speaker-High-To-Low-Amplifier-Audio-Impedance/192292898220?epid=2216194726&hash=item2cc58cc5ac:g:E~QAAOSwqtlZlT3D


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PostPosted: Sun Apr 15, 2018 6:50 pm 
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Hi,

VegliaAudio answered my questions. So, the CAM vote seems to be 1) split off the pre-amp with a Y connector, or 2) use piggy-back RCA plugs on the amp and that give you an identical overall impedance to 1), and/or 3) use 'tape out' to drive the sub which cancels out any equalization shaping, including volume control, which, by the way, is actually a form of equalization. I used tape out on many integrated amps back when I drove subs. I can't see what all the fuss is about. Audiophiles are born fiddlers anyway.

If space behind your components is an issue, then opt for door #2.

Cheers,
David Neice

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PostPosted: Mon Apr 16, 2018 4:10 am 
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Thanks everyone for your thoughts!
V


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