Forums - SE84UFO2.1 doesn't work in mono config

Bart Verified Member Posts: 5	SE84UFO2.1 doesn't work in mono config 02/06/25 at 15:26:26 Hi, Is there someone who has a SE84UFO2.1 that does/didn't work as it should be (and using Decware Y-cable and as said in the manual) in mono configuration? And if so, how did you make it work properly? Regards Bart (from the Netherlands)
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CAJames

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Re: SE84UFO2.1 doesn't work in mono config
Reply #1 - 02/06/25 at 15:46:59

Hi Bart,

There are a few of us, including me, who are successfully using our UFO amps in mono configuration, and it always works just as described in the manual. But let me ask a few questions to see where you are.

What is your source?

Have you confirmed the amp(s) work properly as stereo amps, with conventional cables?

Are you connecting the outputs as described in the text:

Quote:

The speaker jacks must be connected in series with a single piece
of wire 10 to 12 inches long. It connects between the left positive
and the right negative speaker jack on the amplifier. The two
remaining speaker jacks, one on each side, are used to power the loudspeaker.

NOT the way shown in the diagram. The diagram is for a different mono configuration, balanced mono and it needs a different cable.

I guess it is possible, but unlikely, there is a problem with the Y cable. Assuming the amp works properly as stereo, you should be able to test both sides of the Y cable by using one at a time for one channel of the stereo amp.

Good luck, let us know what you find.

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[FOOBAR2000 | Jay's CDT2 MRK3] -> Denafrips Terminator 2 + Gaia
Sumiko Pearwood -> Mapleknoll Athena -> Luxman SUT -> Mapletree Phono 3E
STR-1002 -> Woo WA22 -> 2x UFO25s, balanced monos
Omega SAM , Hifiman Arya, Audeze LCD-XC

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Bart

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Posts: 5

Re: SE84UFO2.1 doesn't work in mono config
Reply #2 - 02/06/25 at 16:00:35

Hi CAJames,
Thanks for replying.

I've been over this topic with Steve for some time now.
He said that it is impossible .... but it isn't!

I've tried all kind of configurations ...
the two amps play great in stereo
one of them plays in mono right away when connected as written in the manual
switching to the other amp /or just have it connected the same way results in total silence ......
I've changed tubes, cables and back ..... same result.

If I put in one rca (Y-cable) (L or R input) it plays (speakers connected using Decware bridge), as soon as I put in the other rca (Y-cable) the sound/music disappears
disconnecting one or the other rca results in ...... music/sound

Regards Bart

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CAJames

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Re: SE84UFO2.1 doesn't work in mono config
Reply #3 - 02/06/25 at 16:21:13

Wow. If Steve can't figure it out I don't think I can help but let me be sure I understand what you're saying.

Quote:

...one of them plays in mono right away when connected as written in the manual
switching to the other amp /or just have it connected the same way results in total silence ......
I've changed tubes, cables and back ..... same result...

One amp works fine in mono. But you take the tubes from the working amp, put them in the other amp, and use the same source, Y cable and speaker connection that worked in the first amp and you get nothing?

If this is correct I can't think of anything else to do but send it to Decware. I know that is inconvenient and expensive, especially from Europe, and maybe someone else has a better idea, but that is the best I can do.

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[FOOBAR2000 | Jay's CDT2 MRK3] -> Denafrips Terminator 2 + Gaia
Sumiko Pearwood -> Mapleknoll Athena -> Luxman SUT -> Mapletree Phono 3E
STR-1002 -> Woo WA22 -> 2x UFO25s, balanced monos
Omega SAM , Hifiman Arya, Audeze LCD-XC

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Steve Deckert

Administrator

If the 1st watt
sucks why continue?

Posts: 6397

Re: SE84UFO2.1 doesn't work in mono config
Reply #4 - 02/06/25 at 17:17:30

I recommend making a video of the amp playing in stereo and then being configured for mono and tested. If an amp works in stereo then it has to work in mono. If we don't find anything in the video you make, we will have you take a picture of the inside of the amp. You can email the video to zen at decware.com

Steve

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Bart Verified Member Posts: 5	Re: SE84UFO2.1 doesn't work in mono config Reply #5 - 02/06/25 at 17:38:53 Hi Steve, Thanks. I'll make a video and pictures tomorrow (it's 18.38h here and dark). Regards, Bart
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