My Pioneer Spec 1 preamp and Spec 2 power amp use unbalanced RCA connectors to interconnect. In my new listening room I would like to separate them by about 30 feet so I think balanced is the way to go. Are there converters for this? I have seen some discussion on baluns but aren't these passive devices? Does balanced need an actual active circuit for the connection in order to take advantage of the benefits? Anyone have a procedure or plan to add balanced in/outputs to an amp set up that only uses RCA?
unbalanced to balanced conversion?
- Thread starter HiFiThor
- Start date
xero-D-hero
Super Member
There are quite a few co.s that make these,but the thing is to use it the way you wanna use it you'll need one of 'em @ both ends.
Usually they are used to convert a piece (or more) of unbalanced gear (RCA -or- 1/4") gear to balanced gear (usually XLR) so only one is needed most times.
Also keep in mind that sometimes a given box only converts one way -or- the other depending on which is needed,other boxess can convert both ways.
Rolls & ART both make boxes like this.
IIRC the ART cleanbox pro is one of them,no doubt there are others.
These are mostly used by folks in the music recording industry so you'll wanna check sites for gear oriented towards that field.
HTH
Bret P.
Usually they are used to convert a piece (or more) of unbalanced gear (RCA -or- 1/4") gear to balanced gear (usually XLR) so only one is needed most times.
Also keep in mind that sometimes a given box only converts one way -or- the other depending on which is needed,other boxess can convert both ways.
Rolls & ART both make boxes like this.
IIRC the ART cleanbox pro is one of them,no doubt there are others.
These are mostly used by folks in the music recording industry so you'll wanna check sites for gear oriented towards that field.
HTH
Bret P.
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xero-D-hero
Super Member
Though I tend agree that a quality unbalanced RCA cable should be ok @ that length,I try to just answer questions as they're asked for the sake of brevity.
FWIW
Bret P.
FWIW
Bret P.
whoaru99
Epic Member
Sure, if the gear has balanced.
xero-D-hero
Super Member
Nah were cool,I just felt I should add that disclaimer for the sake explaining my comments better.
Bret P.
Bill Ferris
Lunatic Member
Hi HiFiThor, I don`t know if you resolved your remote amp/preamp setup as posted a little more than a month ago as I just stumbled across your post.. I had the same kind of situation in 1995.. What I tried first was to run 40 ft. custom made Monster Cable interconnects between the remote amp and preamp.. It worked but also had ground loop hum and switching noise from light/ceiling fan switches, ect. because of the preamp was plugged into one power circuit & and the power amp in another.. I tried to isolate with Cat 5 cable & baluns later on and also line level RCA to RCA isolators, but neither passed any signal because of the very low impedance output of the preamp was basically shorting out the galvanic isolation transformers of either type of method.. What I ended up doing was to run a small 16 ga. extension cord from the power amps 120 volt power source to the preamp and its low powered connected devices(tuner, CD player) so all connected audio gear was at, or nearly at the same ground potential, which greatly reduced the ground hum noise.. Anyway, FWIW. that worked well for me until I totally reworked the whole setup differently years later.. I don`t know of any other HiFi quality "safe" ground loop prevention/breaking methods, though others on this site might.. The" common ground power source" feed setup that I described above worked every time for me when I setup and ran PA`s for rock bands with all the power amps on stage and the mixer, eq`s, crossovers, & effects were out in the audience fifty or more feet away, even when there was a closer power outlet nearer to the sound board in some cases.. Just my .02 worth. Good luck with whatever method you end up using & enjoy the music Sir.. Regards, OKB
Thank you for your input! I did not think about ground loops in the AC power distribution in my home. This is very relevant because I am going to build a new home and now I can specify a separate dedicated 30 amp service to my listening room. Great advice from you.
I bought a couple of unbal/bal converter boxes which are powered and allow for long low impedance balanced connection. I was looking at them and started to think about what exactly is going on with this. My Spec-1 is limited to a max of a 2 volt output, which doesn't seem much to work with. I have not looked into it but I am thinking that preamps that have balanced outputs can actually start with a high amount of output signal, more than 2 volts. The Spec-2 power amp has input level controls to adjust for connections to preamps like this. I just wonder if I am making something out of nothing. Trouble is I cannot actually hook this stuff up and test it all until I get my home built.
B_F: Oh, there also would be several other solutions, both wired and wireless. For example, one could also go: output -> ADC -> optical SPDIF cable -> DAC -> input. However, many of these other solutions would seem likely to sound at least a bit different compared to the pre- and power-amp directly hooked together as intended.
Greetings from Munich!
Manfred / lini
Greetings from Munich!
Manfred / lini
Bill Ferris
Lunatic Member
HiFiThor, I don`t think you need to concern yourself with the 2 volt Spec 1 preamp unbalanced output level being a problem.. It has not ever been for all my friends & my self`s stereo setups of varying complexities.. While more modern home stereo gear is showing up these days with balanced inputs and outputs which can have decided benefits especially with difficult and complex setups and it`s higher signal output capability can be helpful in some situations.. Granted, a balanced line level connection setup is the best, if all the connected gear provides for it, it`s what the pros use.. I guess I`m the impatient type.. I would in your situation temporarily set up your setup as close as it could be to the way it with be in your new house using the active bal/unbal converter boxes connected up and with the preamp in one room and the power amp in another with the cables connected to see if this scheme has any chance of working properly.. I have never been married, so my whole house is a Man Cave and I can rig up & test out rigs without concern about offending or pissing off a wife or having children stumbling across the temporarily strung wires across the floors and have set up complex concept test rigs("feasibility study") many times over the years before committing to them.. But that`s my situation and yours might not allow for the test hookup.. Anyway Sir. I`m glad to have been of some help to you.. Good luck and take care.. Regards, OKB 
whoaru99
Epic Member
Personally, I think you have the boxes unnecessarily. Decent RCA cables are nearly a sure bet to work, and the converter boxes do nothing to alleviate ground loop and may even cause more problems if they, themselves are powered.
The max output of your Spec 1 is NOT 2V. That is the nominal output. MAX output is 7V. Of course, what comes out is proportional to the signal level going into the pre amp from the sources and the volume control position.
While pre amps having balanced outputs may in fact have higher output simply because it's a differential voltage, a balanced input normally also requires more input so overall output/input ratio is typically same/similar.
Note, however, regardless if unbalanced or balanced, they all start at 0 output with the volume all the way down, and go up from there as you increase the volume setting.
Your Spec 2 amp requires 2V input for full rated output. If you don't necessarily need full rated output then you don't need to have capability to supply 2V to the amp. Again, bear in mind this is a variable signal from the pre amp to the amp. 0 with the pre amp turned all the way down, up to whatever it takes to get the volume you want within the limits of the amp. For typical listening the signal level from the preamp to the power amp will be only some millivolts. For example, roughly 125mV (0.125V) from the pre amp will cause about 1 watt per channel of power from the amp to the speakers.
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Bill Ferris
Lunatic Member
I`m sure there are Manfred, but I personally prefer the most direct method, if possible. When, in 2009, I had five rooms( + a 4K living room projector) of my house wired with 5 circuits of high quality Belden Mediatwist Cat 6 + cable with the signal specific baluns at the source(my living room`s rack) and at each room. I had (1) 2 channel audio(upgradable to 4 channel), (1) SVGA(hd15) for the rack`s lap-top feed, (1) 1080p HDMI(upgradeable to 4K), (1) RGB, & (1)S-Video + composite, all my previous hum ground loops, picture noise, ect. went away.. I have in all those rooms a LED flat screen and either a receiver, integrated preamp/power amp, or separate components, so each room has local selection and level control with wireless IR repeaters to control the living room`s rack(AKA the octopus head) BluRay player, selection of audio sources, security cameras, laser disc player, ect. All with excellent sound and picture.. I really don`t like to trust wireless for anything but WiFi and a handful of wireless added on FH/SS security cameras. I spent nearly a year thinking about how I wanted to do this before paying my A/V dealer to run all the Cat cable feeds and to be performance + bandwidth certified by a separate contractor.. Just my old school way of hard wiring doing things for absolute reliability.. Thanks for your suggestions and comments Manfred.. Take care Sir. Regards, OKB
HiFiThor, I don`t think you need to concern yourself with the 2 volt Spec 1 preamp unbalanced output level being a problem.. It has not ever been for all my friends & my self`s stereo setups of varying complexities.. While more modern home stereo gear is showing up these days with balanced inputs and outputs which can have decided benefits especially with difficult and complex setups and it`s higher signal output capability can be helpful in some situations.. Granted, a balanced line level connection setup is the best, if all the connected gear provides for it, it`s what the pros use.. I guess I`m the impatient type.. I would in your situation temporarily set up your setup as close as it could be to the way it with be in your new house using the active bal/unbal converter boxes connected up and with the preamp in one room and the power amp in another with the cables connected to see if this scheme has any chance of working properly.. I have never been married, so my whole house is a Man Cave and I can rig up & test out rigs without concern about offending or pissing off a wife or having children stumbling across the temporarily strung wires across the floors and have set up complex concept test rigs("feasibility study") many times over the years before committing to them.. But that`s my situation and yours might not allow for the test hookup.. Anyway Sir. I`m glad to have been of some help to you.. Good luck and take care.. Regards, OKB
One of the design considerations of my new home was that I have a dedicated space to fully exploit my HiFi habit. A big space. I have been compromising my love of of Stereo for far too long. When I drop the needle on Rush or Beethoven you are going to know it. I do not expect to hear "Turn it down" or "The kids are asleep" or "My ears are bleeding!" I live in the middle of 5 acres in a rural setting. If I blow up something I'll just fix it or get something stronger.
Bill Ferris
Lunatic Member
Yes Sir. Excellent mindset HiFiThor !! Kudos Sir.
My sonic Brother of another mother. 
Take care and good luck with your sonic pursuit.. Warm regards, OKB
aabottom
Swing
Good thread here. I'm considering a Multi room audio system using XLR balanced cables. See my design/ build thread here:
http://audiokarma.org/forums/index.php?threads/multi-room-audio-system-xlr-balanced-cables.826312/
http://audiokarma.org/forums/index.php?threads/multi-room-audio-system-xlr-balanced-cables.826312/
triode17
Super Member
Yes but it should be low capacitance cable. I ran about 30 feet from one room to another and ended up with a high freq. oscillation. So, I built an active impedance buffer to solve the problem.
Old thread, may be irrelevant now, but...
I agree with Whoaru, but would say "decent RCA cables", on a 30-ft run, should be at least double-shielded and one of the shields should be continuous foil. Gaps in the normal braid let RFI leak in, like holes in a ship's hull — not an issue with the normal 3-ft run, but very loud when multiplied times 10. I used Mogami's best-quality interconnect cable for 26-ft runs and the hum was intolerable. Switched to cable with a foil shield under the braid and it was silent.
TV / Internet cable companies install miles of cable, highly susceptible to outside interference: such a length is an antenna. They use cable with continuous foil shielding, plus an additional four layers of braided shield around it.
KentTeffeteller
Gimpus Stereophilus!
And they also have distribution amplifiers so they can run that cable those distances.
