You really haven’t experienced the full benefit of “true” dual mono amplifier set up as you are using 2 stereo amplifiers “bridged” where amplifier phase of one channel has been inverted - that is why you are now using the positive L and R terminals for a single speaker. Bridging typically halves the minimum impedance the amplifier can safely handle, lowers the damping factor, and increases THD and noise. Bridged amplifiers are typical limited to speakers with a nominal 8 ohm impedance with no significant dips below 6 ohms.
Moving from a stereo amp to a dual mono set up
I thought this would have been not much a change and easily accomplished.
Boy was I wrong. I found a second Plinius SA102 on Audiogon a few months ago at a great price. I had it drop shipped to Ralph Abramo for a good going through. A few weeks later and it was done so I drove to his shop to pick it up. I asked about how to set up the amp for dual mono. A easy thing to do. Change the position of a switch in the back and connect the speaker wires to both R / L positive leads and connect the input to the right channel.
My speaker wires are Straight Wire Cresendo 3's. The leads are not able to reach the 9" spread to the positive speaker connections of the amp. I spoke with Straight Wire, they can alter the cables to a 12" long lead so they can reach. OK, shipped them out yesterday.
Now considering my electrical plug issue. One more plug is something I do not have. I have a older PS Audio AC filter that can receive up to 8 inputs. But I do not like the idea of running 2 high power amps through it. I want to do directly into the wall for my power.
I called an electrician and he is coming over next week to do a Job Walk. to see what it will cost to add a new circuit to my power panel and run the wires for a new plug.
Then there is the physical amp to deal with. I need a second stand to get the amp off the floor.
I will have to disconnect and move my existing equipment and stands around to make the system visually balance out.
Then there is still one question I am not sure of. Do my current XLR cables from Preamp reach across to the new positions of the amps. Are they long enough?
All this equipment is between the speakers. I like where the speakers are right now.
Any home that one considers to buy ought to have it's wiring checked for aluminum wiring prior to a signature on the documents. It can function fine if kept within it's limits. Lights and lighting are typically fine, but any circuit posed with a varying amp load ought to be replaced; however, if one circuit is being swapped out, it's better to bite the bullet and change everything and ignore the 'grandfathering' option. We had a house that was all knob and tube next to live gas lines, the latter got disconnected and vented. A latter one has one continuous ground for all the circuits, making 'short circuit searches' a real bug chase.... Know ahead of what you want to upgrade....copper and alum wiring together in one installation is considered a real hazard... "Know thyself....Then, know everything else in close proximity to you and ;oved ones....." ;) |
So why are they connecting positive and positive from speaker wires supposed to be connected to positive and negative? Why would they internally wire it this way when it’s to be used for mono after being bridged over from a stereo amplifier? Why not use the four individual amps in a biamp configuration? |
Regarding setting on the Plinius. The amp is a designed with a switch on the rear of the unit to run in Stereo, or Mono and which inputs I am using. I am using the XLR inputs. SO I move the switch to the Mono position with XLR Inputs. So my connection is to connect to the right channel input. The speaker connection is Positive speaker wire to the Positive Right channel, Negative speaker wire to the POSITIVE left channel. There is a distance of 9" to those 2 binding posts on the back of the amp. That is why I sent my cables to be altered, the speaker wire leads could not stretch that far apart. Shipped them on Thursday. Straight Wire will be getting them tomorrow. They should be back in UPS by Friday. I might have them by the 19th of this month. Bu then I hope the electrician is done. I should only take about 4 hours max for them. And I am sure I will have to move my system off the back wall to give them some room to work. So, I can then reposition everything so things reach. Good thing I have a second system in the same room to use for my birthday and the holiday weekends we have coming up. |
@61falcon yes you are correct thar makes big difference more than just ground loops. I would also suggest 12 3 wire not just 14 3 wire. As long as it is being rewired heavy wire is a good thing. Make the wires in the wall identical length as well. . I changed the feed wire to my house from aluminum to copper. That was a good improvement acr9ss the board. Went to a 200 amp service and when I needed the wire going to the house to be heavier I paid the extra for copper. It was well worth it. Also you might want to have better receptacles put in as well. Furutech I have been very happy with. Lol power is a slippery slope. As the improvement is hard to believe. But much cheaper than most other items |
Congratulations plinius are very good.I own SA100 for more than 25 yrs now. The cost of electrician doing your project depends on how mow much work and he will spend to install it and how greedy he is?This hobby when you add gear or cables it change the sound.With mono beside they are heavy you need extra space to accommodate them? And maybe longer cables. Lots of work needed .At the end of you do it right , you will be happy enjoying music. |
Before you drop some big money on redo’s, etc., why not try DSP to correct some of the shortcomings your’e experiencing. Until recently I was totally against it, feeling I was cheating or something, but it came down to weather I wanted great sound or not so I gave it a try… It may not be morally right for everybody, but I gotta tell ya… Fixed the issues I was experiencing allowing me to enjoy my set up and room again. Just a recommendation. |
Thanks for sharing your experience. We’ve probably all been there. It’s why this hobby is a journey and not a destination. Enjoy the journey. If not it’s like taking the kids on a long car ride on vacation with shouts of, Are we there yet? Are we there yet? Please keep us updated on your progress and as Hans says, enjoy the music! |
Bill, you forgot a step. Walking into the backyard at 2 in the morning, staring at the stars, and cursing the stereo gods for tempting you into this hobby! I feel your pain. I recently moved into a new house and was psyched that I could finally setup a dedicated listening room in a spare bedroom! A year later, I'm to the point of starting over. The room is too small, the seating position is too close, too many windows, the equipment rack is too big, I can't get the bass issues under control, and the electrical circuit is undersized and unstable. So, now I'm going to build a dedicated listening room in the basement. (more $$$) Damn those gods on Mount Audiophile! Keep us appraised on how things go. - Jeff |