Wire up my LFR - dumb-ass guidance needed

Posted by: oakvillematt

Wire up my LFR - dumb-ass guidance needed - 06/05/14 02:58 PM

It seems that us humans like to make everything more complicated than it needs to be.

I have a Pioneer receiver that has RCA pre-out's

I have an Anthem MCA5 that has both RCA and XLR inputs

I now have a DSP that has to go between those two units that also has RCA and XLR inputs/outputs


General rule of thumb for audio is that 16AWG wire would be better than 22AWG wire. (Thicker must be better). XLR runs two wires and seems to be better at no hummmmmmmm but costs more.

I don't believe that RCA cables made from that $300 unobtainium sound remarkably any different than a well made $6 RCA cable from monoprice.

I can buy an RG6 (18AWG core) RCA cable for $6 for a 6' cable.
I can buy an RCA to XLR (16AWG core) cable for $9 for a 6' cable. an XLR m/f cable is about $10

Sadly they are all out of 3' cables..

So I can spend that extra $40 for XLR connectors that won't come loose or fall off, but will they sound any better? or just be another thing to go wrong?
Posted by: Socketman

Re: Wire up my LFR - dumb-ass guidance needed - 06/05/14 03:21 PM

In my front room setup I am using rgb cables from my preouts to my amps. I like to use rca cables that have shielding other than that I don't feel their is any difference. I used a set of unshielded cables on my sub and it hummed and vibrated like a mofo .
Posted by: cohesion

Re: Wire up my LFR - dumb-ass guidance needed - 06/05/14 05:15 PM

Hi Matt,

I believe that XLR cables are technically better than RCA's and I have a controller with XLR pre-outs so I've run all XLR to my DSP and from there to my amp. However, I went to great lengths to find the most affordable basic but decent quality XLR cables with Neutrik connectors that I could find. In fact I ended up buying them from a music and pro audio store rather than a stereo shop. No unobtainium or even expensivanium for me!

Having said all this, for short runs of cable the XLR probably makes no difference compared to the RCA. On the other hand, there's a lot of wiring and channels of amplification for the LFR's alone. Add in my HT setup and its additional required cables and there is quite the twisted mess of spaghetti behind my system. I guess the XLR is a relatively low cost way to reduce the potential gotchas that might arise from this!
Posted by: Socketman

Re: Wire up my LFR - dumb-ass guidance needed - 06/05/14 05:37 PM

With carefull cable routing and the use of the shortest cable necessary an unbalanced connection will work just fine.
Posted by: Serenity_Now

Re: Wire up my LFR - dumb-ass guidance needed - 06/05/14 08:00 PM

Stay unbalanced if that is what your preouts are. Get quality shielded rca cables and you are in great shape. They should be inexpensive anyway. You can make your own out of quadshield coax.

XLR cables are born of pro audio and are great for long cable runs. If you start as unbalanced, the point of XLR is moot.
Posted by: JohnK

Re: Wire up my LFR - dumb-ass guidance needed - 06/05/14 10:03 PM

Matt, yes it does appear that you're making this more complicated than necessary. A balanced 2-conductor connection using XLR at each end can have greater interference(hum)rejection than coaxial cables with RCA plugs at each end, but this would be meaningful only in the presence of unusually high interference levels which usually don't occur in typical home installations. The usual shielding in coaxial cables is entirely sufficient for such installations.

Also, as the previous reply touched on, a balanced connection requires a balanced output in the first unit to send out two signals(but reversed in polarity)rather than the one signal carried by the one center conductor in coaxial cables. A single output, such as the one from your receiver, can't do this and using an RCA to XLR cable makes no difference.

While gauge is a significant factor in long runs of speaker wire it is of no significance in low level interconnecting cables. RG6 is unnecessary for such use and I use the thinner, more flexible RG59. If you need 3 foot cables these should be satisfactory.
Posted by: iloveturbo

Re: Wire up my LFR - dumb-ass guidance needed - 06/06/14 08:30 AM

Matt,

Any quality RCA cable will do the trick really. XLR is designed for long-haul transmission or pros who run into situation with high level of EMI can not be avoided. Besides, unless you run end to end XLR (which I plan to do), you would be wasting your money anyway.

If you decide to go with XLR anyway, just make your own if you are handy with soldering. This is what I am using

Canare L-4E6S Star-Quad Microphone Cable $0.50 per ft
Neutrik XLR connectors $5~6 per pair

Cheers

Howard
Posted by: oakvillematt

Re: Wire up my LFR - dumb-ass guidance needed - 06/06/14 12:32 PM

Originally Posted By: iloveturbo
XLR is designed for long-haul transmission or pros who run into situation with high level of EMI can not be avoided. Besides, unless you run end to end XLR (which I plan to do), you would be wasting your money anyway.

If you decide to go with XLR anyway, just make your own if you are handy with soldering. This is what I am using

Canare L-4E6S Star-Quad Microphone Cable $0.50 per ft
Neutrik XLR connectors $5~6 per pair


Yes, I have XLR cables that I use with my daughter for her mic too feed into an 8 channel mixer. She likes to put on performances with her friends in the back yard and $100 for 3 mic's cables and a mixer vs. the smile on her face when she gets to perform for the neighbours who can now hear them.

But for my case, XLR also had additional properties that I like. For instance, a CLICK and it locks into place. The weight of the cable can't slowly pull it loose.

I can buy a good XLR cable for $10. Or with your prices, make the same cable for $9. I think my time is worth more than a dollar.
Posted by: chesseroo

Re: Wire up my LFR - dumb-ass guidance needed - 06/07/14 02:41 PM

Originally Posted By: oakvillematt

General rule of thumb for audio is that 16AWG wire would be better than 22AWG wire. (Thicker must be better).

I'm surprised John hasn't pulled out the always educational Roger Russell link again.
I'll beat him to it!
http://www.roger-russell.com/wire/wire.htm
Posted by: cohesion

Re: Wire up my LFR - dumb-ass guidance needed - 06/08/14 05:29 PM

Originally Posted By: Serenity_Now
Stay unbalanced if that is what your preouts are. Get quality shielded rca cables and you are in great shape. They should be inexpensive anyway. You can make your own out of quadshield coax.

XLR cables are born of pro audio and are great for long cable runs. If you start as unbalanced, the point of XLR is moot.



If we all didn't start out so fundamentally unbalanced we wouldn't have nearly so much fun hanging around this forum!
Posted by: Serenity_Now

Re: Wire up my LFR - dumb-ass guidance needed - 06/08/14 07:23 PM

Unbalanced all the way!
Posted by: fredk

Re: Wire up my LFR - dumb-ass guidance needed - 06/08/14 08:18 PM

Originally Posted By: Serenity_Now
Unbalanced all the way!

Unbalanced is the only way. Sanity is highly overrated.
Posted by: Andrew

Re: Wire up my LFR - dumb-ass guidance needed - 06/09/14 04:57 PM

Hi Matt,

To answer your specific question about connecting the LFR DSP between your receiver pre-outs and your amplifier, you absolutely want to stay with the same connection type both in and out. The reason for this is that the DSP has a fixed gain of unity or 1:1. It does not apply any gain to the signal path. This is fine if you maintain the same input and output connection, but if you were to use the RCA inputs and then connect to your amplifier using XLRs, the overall gain of the DSP would now be -6dB. If your amplifier requires more than 2Vrms in to reach full power, you would then clip the input of the DSP before reaching your maximum amplifier output which is a bad situation. That's why we always recommend staying with like connections.

For the broader question about XLR connections in general, I have found them to be beneficial between pre-amp and power amp if the amplifier is situated more than 6 feet away from the pre-amp. A true balanced connection can also help if you live in an RFI rich environment (near a radio or cell tower) and also gives some benefits in terms of reducing the background noise floor and residual hum due to ground loops.

Thanks,

Andrew
Posted by: cohesion

Re: Wire up my LFR - dumb-ass guidance needed - 06/10/14 07:18 AM

Originally Posted By: Andrew
Hi Matt,

To answer your specific question about connecting the LFR DSP between your receiver pre-outs and your amplifier, you absolutely want to stay with the same connection type both in and out. The reason for this is that the DSP has a fixed gain of unity or 1:1. It does not apply any gain to the signal path. This is fine if you maintain the same input and output connection, but if you were to use the RCA inputs and then connect to your amplifier using XLRs, the overall gain of the DSP would now be -6dB. If your amplifier requires more than 2Vrms in to reach full power, you would then clip the input of the DSP before reaching your maximum amplifier output which is a bad situation. That's why we always recommend staying with like connections.

For the broader question about XLR connections in general, I have found them to be beneficial between pre-amp and power amp if the amplifier is situated more than 6 feet away from the pre-amp. A true balanced connection can also help if you live in an RFI rich environment (near a radio or cell tower) and also gives some benefits in terms of reducing the background noise floor and residual hum due to ground loops.

Thanks,

Andrew


So this isn't a dumb question at all! In fact, now I need to ask a follow-up question based on my own setup. In it, I've used XLR outputs from my pre-pro to the DSP. Then I've used XLR outs for Left and Right (both front and rear) from the DSP to my ADA for the LFRs. However, I'm using an older amp for my centre and surrounds and it doesn't have XLR inputs. Thus I've run an RCA out from the DSP to the input of the amp for the centre.

I haven't noticed any issues yet but is this also reducing the gain of the DSP? Should I switch to all RCA for my centre channel?