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04/14/26 at 12:49:44

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Dual SE84UFO25’s Inbound… (Read 75 times)

HeresyGuy33

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Posts: 8

Dual SE84UFO25’s Inbound…
Yesterday at 01:09:24

I posted last week about my wait being over after 3 years… When I first went on the waitlist it was for a Torii MKV. About a year into the wait I switched to a Sarah. But when my time came, and after having read the design log and everything else I could get my hands on over 3 years, I decided the SE84UFO25 was the piece I wanted to pair with my Forte IV’s.

Then I thought to my self…. You waited 3 years… you’ll only do this once…they’re stunning to look at and Steve had great results bridging them in the test phase.. the Fortes are supposedly 99db sensitive but in the real world probably more like 93-94db. So let’s get two and get the extra few watts and a little headroom in my fairly small space.

Not sure I’ve ever been this excited over new equipment before. The last week has seemed longer than the last 3 years. As I mentioned in my other post am pairing the 25’s with a Luxman CL-38uc tube preamp which I have re-tubed with new Gold Lion 12au7’s and 12ax7’s.

I’m curious if anyone has paired the 25’s with Forte IV’s and if so which of the included tubes worked best for you?

Also I know you run dual 25’s CAJames and if anyone else does I’d love to hear from you as well. How was your break in period? Any advice or tips around running them bridged?

Thanks in advance.

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MM Seasoned Member Posts: 495	Re: Dual SE84UFO25’s Inbound… Reply #1 - Yesterday at 05:01:24 Congrats on your soon to be 25’s! I didn’t realize getting a pair of amps when you’re on the list for one was an option. Had I known I probably would have done the same. I think you’ll be happy!
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GroovySauce

Seasoned Member

Posts: 922

Re: Dual SE84UFO25’s Inbound…
Reply #2 - Yesterday at 14:07:40

Oh boy that is exciting!

I don't know about bridging the UFO25 or matching with the Fortes.

My suggestion is to listen and get a sense of how the amp sounds with the supplied tubes. Let the amp burn in for 100+ hours. The amp will change sound significantly in this time. Try swapping out the front VR tubes for a different voltage. This will give you a groundwork for future tuning.

Once you get a sense of how the A, B and D (VR tubes) affect the sound when you roll the input tube, you will know whether you can tune to your taste with the VR tubes. Remember the bias switch too, this gives you 6 different profiles.

Try both the 4 and 8 ohm taps.

The UFO25 is so tunable it's crazy. My experience this is a solid base to start fine tuning to exactly what you are looking for.

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CAJames

Seasoned Member

"I've run every
red light on memory
lane."

Posts: 3187

Re: Dual SE84UFO25’s Inbound…
Reply #3 - Yesterday at 16:38:14

I will +1 everything Groovy said above. I found the "worst" of the burnin was over after 50 to 60 hours, and after that things just got better and better.

As for tubes, you will of course need to figure out what you like, but I like an 0D3 in front and high bias for my input tubes. After 2+ years I've largely settled on 7DJ8/PCC88 and 5670/396A types. I'm allergic to new production tubes anyway, and neither of those types have been made for decades, so if buying old tubes is a problem for you you'll have to look elsewhere. I've also had good luck with PCC189, and Soviet 6N5P and 6N6P tubes. 7DJ8 and 6N[5|6]P tubes are available from Decware.

Power tubes and rectifiers are a similar rabbit hole. Most UFO owners stick 6P15P type tubes. Replacements are available from Decware intermittently but I think most people get them from ebay. If you're buying on ebay my advice is to buy several and listen to each of them. Getting ebay 6P15P tubes is like a box of chocolates, you never know what you'll get. For me personally I've found I like EL822 and EL83 type power tubes a little better. But they require adapters.

Similarly with rectifiers there are a gazillion types out there, and a bazillion thread about them on this site. Here is a relatively recent one with a lot of good information:

https://www.decware.com/cgi-bin/yabb22/YaBB.pl?num=1709666967

Also, if you want to be double extra obsessive different VR tubes in the back can also be interesting. And they can be had relatively inexpensively on ebay or other online sellers or you can get them from Decware.

Regardless of how much gratuitous tube rolling you want to do I think it is important to have a complete set of backup tubes on hand because you never know when a tube will fail. If you got the Decware tubeset with your amps then you have most of what you need already.

Now for bridging. What is/are your source(s)? My limited experience with (standard) bridging is it just gives you more power. I like balanced, and feel like if you have balanced sources configuring the amps as balanced monoblocs is a big win. The details are in the manual, and if you have questions I'm happy to help.

Please keep posting as your journey continues, and good luck and good listening.

[Volumio | 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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