XLR to RCA Subwoofer new idea?

[syzygy]

I hate RCA unbalanced cables and would avoid them at all costs if possible.

There is no reason for them to exist.

It's like twin lead 300 ohm TV antenna cables.

What?

 

[JimA84]

Can't imagine basing a subwoofer choice based on rca vs xlr input. Or worrying about it.

I have had severe problems in the past with >6ft unbalanced cables

What is frustrating is that I really like the KEF KF92 but the RCA input presents issues. OTOH I would probably still buy them and use a pair of Jensen PC-2XR converters located next to the subs with a 2 foot RG6 RCA cable to the sub.

The other obvious choice would be the B&W DB3D which costs $1,500 more per unit just to get a native XLR input.

I'm also a little bothered by B&W's decision to put the heat sink underneath the base. This would seem to present needless ventilation issues merely in the interest of style. I could live with B&W's "app based" control interface, but putting the heat sink underneath seems like a dubious solution. In addition to the absurd price increase of $1,500 per unit for the DB3D over the KEF with XLR being the only significant difference.

 

[JimA84]

What?

300 Ohm twin lead is the natural means to connect a dipole antenna to a broadcast TV set. It was long ago largely supplanted by 75 Ohm shielded cable using matching transformers.

 

[waynel]

I have had severe problems in the past with >6ft unbalanced cables

What is frustrating is that I really like the KEF KF92 but the RCA input presents issues. OTOH I would probably still buy them and use a pair of Jensen PC-2XR converters located next to the subs with a 2 foot RG6 RCA cable to the sub.

The other obvious choice would be the B&W DB3D which costs $1,500 more per unit just to get a native XLR input.

I'm also a little bothered by B&W's decision to put the heat sink underneath the base. This would seem to present needless ventilation issues merely in the interest of style. I could live with B&W's "app based" control interface, but putting the heat sink underneath seems like a dubious solution. In addition to the absurd price increase of $1,500 per unit for the DB3D over the KEF with XLR being the only significant difference.

The Rythmik F12 costs $1250 in piano black , has XLRs and would absolutely crush either of those subs with one F12 roughly equaling the output of 4 KF92s at 20Hz.

 

[syzygy]

300 Ohm twin lead is the natural means to connect a dipole antenna to a broadcast TV set. It was long ago largely supplanted by 75 Ohm shielded cable using matching transformers.

You hate unbalanced cables?
You say they have no reason to exist?

But 300 ohm twin-lead is a balanced transmission line - and you think that also has no reason to exist?

300 Ohm twin-lead is the simpler, purer way to connect an antenna to a receiver. It's also less lossy & lower cost, because it doesn't require the added expense and additional insertion loss of a balun transformer.
300 ohm twin-lead is still very much used in radio, where signal loss is the enemy.

That a balun and coax is more popular comes down to convenience, not effectiveness.

And RCA is also very effective for short distances.

 

[Speedskater]

I hate RCA unbalanced cables and would avoid them at all costs if possible.

There is no reason for them to exist.

At least in a hi-fi system.
Bill Whitlock, @jensen Transformers (retired) said that a long time ago.
And repeated it often in his papers and articles.

 

[syzygy]

At least in a hi-fi system.
Bill Whitlock, @jensen Transformers (retired) said that a long time ago.
And repeated it often in his papers and articles.

 

[Cbdb2]

The last time I used a RCA cable (an "adapter" cable is unbalanced) with active monitors I got a nifty AM radio receiver. I generally try to avoid unbalanced for anything beyond about 6 feet.

You need to demodulate an AM station, a cable won't do that unless there's a bad solder joint or corroded connector. Are you close to a transmitter? I would still take the few minutes (probably a lot less time than its taken
to write these posts) go try an unbalanced cable. How long is the run?

 

[Cbdb2]

At least in a hi-fi system.
Bill Whitlock, @jensen Transformers (retired) said that a long time ago.
And repeated it often in his papers and articles.

Bills papers are usually about pro installations where it actually makes a difference.

 

[Cbdb2]

Why can't we have equipment that is designed for end to end sound quality instead of either crap consumer features or simply cost cutting by MBAs?

Because 99% of home systems don't have a problem with unbalanced connections, and 99% of these customers don't want the extra cost of xlrs. The back of most AVRs would have to be twice the size. Just because its a balanced XLR dosnt mean you won't have any of these problems, there are many different circuits used for this all have different outcomes, the only true balanced systems use transformers, and the good ones are at least $50x2 per channel which would cost you $200 a channel. Bill also has papers about this.
As far as sound quality, compare Amirs measurements on gear that has both outputs, the differences are inaudable.

 

[Blumlein 88]

They could always have replaced RCAs with your normal 1/8th inch headphone jack used balanced. Space problem solved, making ground contact upon insertion solved. Better immunity to noise.

 

[Speedskater]

Bills papers are usually about pro installations where it actually makes a difference.

Well no. (RCA interconnects have never had a place at the pro level)
While his Audio Engineering Society papers are at the pro level, his seminar papers, his magazine articles and his blogs are often at the audiophile level.

 

[Sokel]

https://www.jensen-transformers.com/wp-content/uploads/2014/08/an003.pdf

You only need to know a couple of things of your pre's output.

Unbalanced to Balanced conversion

Hi, I have an unbalanced preamp and a balanced amp. Why is there a converter box like this https://www.amazon.com/ROLLS-MB15b-Promatch-and-More/dp/B0002IL4B4 if you can just use cables like these? https://www.amazon.com/gp/product/B0957Z55HH/ I am trying to understand the...

www.audiosciencereview.com

So,you see you will need more for the other way around.

 

[Chrispy]

I have had severe problems in the past with >6ft unbalanced cables

What is frustrating is that I really like the KEF KF92 but the RCA input presents issues. OTOH I would probably still buy them and use a pair of Jensen PC-2XR converters located next to the subs with a 2 foot RG6 RCA cable to the sub.

The other obvious choice would be the B&W DB3D which costs $1,500 more per unit just to get a native XLR input.

I'm also a little bothered by B&W's decision to put the heat sink underneath the base. This would seem to present needless ventilation issues merely in the interest of style. I could live with B&W's "app based" control interface, but putting the heat sink underneath seems like a dubious solution. In addition to the absurd price increase of $1,500 per unit for the DB3D over the KEF with XLR being the only significant difference.

I've not had such issues with rca cabling, even over 6', altho most of my subs tend to be driven by rack amps and speaker wire. That Kef & B&W look awfully pricey for what they are.

 

[rationaltime]

Zero in effect of noise which is the whole point.

Look at the circuit of a differential interface like the XLR.

The (-) simply extends the signal in the opposite direction from reference ground.

In other words you need to drive the (-) channel below reference ground.

I guess I might have overthougt this because you would have to invert the phase on the (-) channel to achieve summation given a common reference ground. Once again the stupid "ground" is a problem.

Of course reintroducing the always plaguing ground issues. Damn, I guess I may have been a bit over enthusiastic.

I guess I should just buy the B&W subs with the XLR inputs.

I just want to avoid the hum and noise problems with RCA cables and the stupid grounding problems that go along with them in trying to interface with unbalanced interfaces

I would rather pay several thousand dollars more for B&W subwoofers than to deal with gimpy attempts to connect unbalanced circuits.

I hate RCA unbalanced cables and would avoid them at all costs if possible.

There is no reason for them to exist.

It's like twin lead 300 ohm TV antenna cables.

I wonder how much it really would have cost for Kef to put a XLR input on the KF92

Especially given the elaborate crossover and high pass filter output features they included.

Why can't we have equipment that is designed for end to end sound quality instead of either crap consumer features or simply cost cutting by MBAs?

I give up. I am so frustrated by these issues, stupid marketing and poor quality and customer service due to MBA ideology.

I think I will just put a Rolls MB15b ProMatch box on my TV and plug a couple Adam T8V boxes with possibly their T10S and just become a spectator.

I want to point some things out to those unfamiliar.

In general, "ground" is NOT a reference level for differential signals.
There is often a common mode voltage other than zero. For example,
in audio applications 48 Volt DC is often applied to the signal lines
and used to power microphones and active direct boxes.

Pin 1 on XLR connectors is connected to the cable shield. It is not a
general purpose ground point.

There are boxes made to convert single ended signals to differential
and the other way. For example, a "DI" or direct box converts single
ended signals to differential. Most have a switch to attenuate large
amplitude input signals.

 

[sam_adams]

Instead of grounding or leaving pin 3 floating, what if we produce a "stereo" XLR to RCA cable to connect to a subwoofer with L+R "stereo" inputs.

Morbo the News Monster explains:

and

Everything you need to know to allay your concerns about this has been explained by Bill Whitlock:

Bill Whitlock - Interconnection of Balanced and Unbalanced Equipment - Jensen AN-003

Bill Whitlock - Hum And Buzz In Unbalanced Interconnect Systems - Jensen AN-004

Bill Whitlock - An Overview of Audio System Grounding and Interfacing - Indy-AES-2012

Bill Whitlock - The Myth and Mystery of Analog Signal Interfaces - AES Detroit -2021

Bill Whitlock - Understanding, Finding, And Eliminating Ground Loops - CEDIA Class EST016

Bill Whitlock - Hum Buzz and Ground Loops - New Insights Into An Old Problem AES Toronto 2010

Bill Whitlock, @jensen Transformers (retired) said that a long time ago.

That user is not who you think it is . . .