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AUDIO FORUMS >> General Discussion and Support >> UFOs as Balanced Monoblocks?
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Message started by CAJames on 07/11/20 at 17:56:32

Title: UFOs as Balanced Monoblocks?
Post by CAJames on 07/11/20 at 17:56:32

Firstly, a little about me. I've been interested in getting a SET amp since I first heard a Cary back in the 90's. But an amp based on the 300B or 2A3 just seemed like to much of a commitment, more like a lifestyle choice than a stereo. And there it sat until a couple months ago I was surfing around and came across the Decware site. And wow, a hand built in the USA SET amp that uses cheap, readily available power tubes and has tube rectification? Yes! This is exactly what I've been looking for.

Then I need to pick what model. I really like balanced connections and I like monoblocks because I really like short speaker cables and my speakers are a stretch even for 6W (eventually I'll get SET friendly speakers, but not right away). But a pair of UFO2s with XLR connections is like 4K$, and it isn't really a balanced amp. Then I see at the bottom of the UFO manual that with the right XLR to RCA splitter I can have 2 true balanced UFO monoblocks for the price of a single UFO2 with XLRs. Yahtzee! Order placed.

So the question is, is anyone else using their amps with XLR->RCA splitters? And what do you think?

Title: Re: UFOs as Balanced Monoblocks?
Post by lazb on 07/11/20 at 18:27:59

DECWARE calls their's a ZBIT. Transformer balanced and not built in so you can use it on multiple devices if you want or need to.
https://www.decware.com/newsite/ZBIT.html

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 07/11/20 at 19:25:54

ZBIT is a balanced to single ended (unbalanced) converter. What I'm talking about is different. You take the 3 XLR pins and break them out into 2 RCA cables as a true balanced connection. One RCA is the + signal and ground, the other is - and ground. There is a picture at the bottom of the SE84UFO manual.

Title: Re: UFOs as Balanced Monoblocks?
Post by ZYGI on 07/30/20 at 13:24:41

CAJames,

Thanks for bring this to my attention. I had a set of cables made and the results with my monos were stunning.

I had been running the Zbit which I love, but this method, is a game changer with these amps.

Zygi

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 07/30/20 at 15:37:17

Excellent! Good to hear it is working for someone in real life.

This is such a cool feature IMO I'm a little surprised no one else wanted to talk about it, but perhaps everyone who is doing it is too busy listening to music to hang out on message boards ;)

Title: Re: UFOs as Balanced Monoblocks?
Post by beowulf on 07/30/20 at 18:00:13

So you buy 2 SE84UFO's and with this custom cable convert them into balanced mono blocks correct? Very interesting ... who makes this cable and why isn't this talked about more?

EDIT:

You can do the same thing with 2 of the SE84UFO3's right?

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 07/30/20 at 18:22:23

So you buy 2 SE84UFO's and with this custom cable convert them into balanced mono blocks correct?

Yes. Essentially you use the left and right channel of a stereo amp as the plus and minus channel of a balanced mono amp.

who makes this cable and why isn't this talked about more?

I got mine from Signal Cable, you can google them. Dono why it isn't talked about more, it seems pretty cool to me. Instead of buying a ZBIT to convert balanced to single ended, spend a few hundred bucks more to buy another amp and use the balanced signal directly, and get double the power.

You can do the same thing with 2 of the SE84UFO3's right?

I don't think so. A true monoblock only has one channel. You need a two channel amp to make this work. You might be able to do it with two UFO3s on each side, but that seems iffy at best, and probably dangerous.

Title: Re: UFOs as Balanced Monoblocks?
Post by beowulf on 07/30/20 at 19:50:04

CAJames wrote on 07/30/20 at 18:22:23:

Yeah, I didn't think that through before asking. You would need a stereo amp to sum the channels. Yes just spending the extra few bucks for a second amp makes more sense.

Another stupid question... this isn't the same as bridging wherein you would get the extra watts associated with that as well is it?

Title: Re: UFOs as Balanced Monoblocks?
Post by deucekazoo on 07/30/20 at 19:58:29

I need to try this with my CS amps. I am not sure why I never thought about this. The old Adcom car amps are wired like this. They use RCA inputs as balanced inputs.

Title: Re: UFOs as Balanced Monoblocks?
Post by ZYGI on 07/30/20 at 20:41:55

CAJames,

I didn't see where Signal Cable made what you need here, Can you refer me to the model you bought.

Most of these XLR to RCA just tie the #1 and #3 to the ground and #2 is the tip. Also a single XLR and a single RCA. I think that is why in the manual it states "custom" adaptor.

One way to tell quick enough....on one mono block reverse the two inputs or swap two the opposite of the other. The speakers will be out of phase with each outer, much like swaping + and - speaker terminals.

Zygi

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 07/30/20 at 20:46:11

Another stupid question... this isn't the same as bridging wherein you would get the extra watts associated with that as well is it?

Yes, you get extra watts. But it is bridging in parallel so I don't think you get as many extra as if you were to bridge in series the "regular" way.

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 07/30/20 at 20:49:30

I didn't see where Signal Cable made what you need here, Can you refer me to the model you bought.

I sent them an email explaining what I wanted, and had them custom made. Mine were $99 for 5' FWIW. I won't have the amps for months yet, so I can't tell for sure, but the cables look good to the multimeter :)

Title: Re: UFOs as Balanced Monoblocks?
Post by Donnie on 07/30/20 at 22:27:56

Are you guys talking about these kind of cables?

https://www.amazon.com/gp/product/B005KBM160/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

I bought a pair of these a while back to run out of my Denafrips's XLR's into Dan the Amp's RCA's.
They are cheap as heck and seem to do the trick.

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 07/30/20 at 22:37:02

No. The cables you need for this are special XLR to 2xRCA. They split XLR pin 2 to one RCA and XLR pin 3 to the other to preserve the balanced signal. If you look at the bottom of the SE84UFO manual there is a picture. The cable in your link just passes the positive signal to the RCA to make the balanced signal single ended. Sort of a poor mans ZBIT.

Title: Re: UFOs as Balanced Monoblocks?
Post by Lon on 07/30/20 at 22:56:02

CAJames wrote on 07/30/20 at 22:37:02:

Sort of a poor mans ZBIT.

And I would believe without the full voltage of the balanced signal.

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 07/30/20 at 23:22:20

And I would believe without the full voltage of the balanced signal.

Yes. You also lose the common mode noise rejection when you don't difference the two phases. You don't get a ZBIT for ten and a half bucks, but it does allow you to plug a balanced source into a single ended device.

Title: Re: UFOs as Balanced Monoblocks?
Post by deucekazoo on 07/31/20 at 14:11:06

From the manual

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 07/31/20 at 16:14:22

Quote:

Posted by: ZYGI Posted on: Yesterday at 20:41:55

...Most of these XLR to RCA just tie the #1 and #3 to the ground and #2 is the tip. Also a single XLR and a single RCA. I think that is why in the manual it states "custom" adaptor.

One way to tell quick enough....on one mono block reverse the two inputs or swap two the opposite of the other. The speakers will be out of phase with each outer, much like swaping + and - speaker terminals.

Title: Re: UFOs as Balanced Monoblocks?
Post by ZYGI on 07/31/20 at 19:04:38

Actually, the way it is wired if you do this with just the single ended signal instead of the plus and minus phases of a balanced signal I think you'll get nothing from the speakers. You'll be driving the + and - speaker terminal with the same signal so there will be no potential across the speaker and no sound, or only a little noise.

James, No the volume remains the same, just out of phase. I did it again, and as you install the first RCA you get "X" volume and it doubles when you add the second.

As far as the wiring, years ago on the early "C's" you could use one set of speaker binding posts on one side, with a jumper to both terminals on the opposite side. If my memory serves me correctly, that was the parallel configuration. Or you could do like the manual states above the balanced configuration, and that method, series configuration.

I run the mono's in the shop during the day while I'm working. I went to switch back to the Zbit RCA in's (shorted or tied together inputs on one channel) with the same output (speaker) wiring as balanced, that was when I had just a little noise, no music.

Either way, you are in for a treat. Sorry you have to wait!!!

Title: Re: UFOs as Balanced Monoblocks?
Post by deucekazoo on 09/17/20 at 16:46:19

So I have been running this setup for about a month now. I made my own cables using the Canare quad cable. The blue wires went to one RCA and the white wires went to the other RCA. I then upbraided the shield, split it into two bundles and ran one of them to each RCA for the ground. I am loving the sound of this setup. If you guys have two of these amps, you need to try this.

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 09/17/20 at 18:25:25

That's awesome, I love hearing stories like this. So, what were you doing with your balanced connection before? A ZBIT?

Title: Re: UFOs as Balanced Monoblocks?
Post by deucekazoo on 09/17/20 at 20:00:21

I never had a balanced connection to these amps. I was using the unbalanced RCAs from the DAC. I did not know this was possible until you pointed it out, so thank you.
I used to run these amps as mono but had them wire up in series, to get the 4-6 watts out of them. So if you think about it, these are very versatile amps. It's a two channel amp, an integrated amp, a mono amp and a balanced mono amp. Then you also have the different tube options.

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 09/17/20 at 21:22:24

Quote:

So if you think about it, these are very versatile amps. It's a two channel amp, an integrated amp, a mono amp and a balanced mono amp. Then you also have the different tube options.

I know. That's why I ordered them

Title: Re: UFOs as Balanced Monoblocks?
Post by Brian on 09/18/20 at 04:04:38

CAJames said: " a pair of UFO2s with XLR connections isn't really a balanced amp"
And also says: "the UFO with the right XLR to RCA splitter I can have 2 true balanced UFO monoblocks "

I do not understand what "Balanced" is. How is it that the amp with the XLR connection - the UFO2, is not balanced, but the standard amp with this new wiring is balanced?

Thanks, Brian

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 09/18/20 at 05:10:43

Quote:

I do not understand what "Balanced" is. How is it that the amp with the XLR connection - the UFO2, is not balanced, but the standard amp with this new wiring is balanced?

A lot of people misunderstand what balanced (I prefer to call it differential, but I'll stick with common usage) means. It is the electronics that are balanced, not the connectors or the interconnects.

Lets start with a "normal" single ended signal. It is the Left and Right channel relative to ground. And it comes out of the amp on the L+ and R+ speaker terminals, with the - terminals at ground. So to voltage difference that drives the speaker is just the voltage of the signal.

In a balanced signal L and R are relative to their inverted signal instead of ground. So a balanced amp (or other component) actually needs 4 separate channels for L+, L-, R+ and R-. And what comes out at the speaker terminals is (more or less) twice the voltage difference. For example the left channel is L - (-L) = L + L = 2L and you get the bonus of canceling any common noise in the two phases when you do the difference.

A balanced signal is traditionally carried on a cable with a 3 pin XLR connection for the + and - phases and ground, but there is nothing magic about the connector or the cable. It is what the component does with the signals that determines whether it is actually balanced or not when it comes out the other side.

What a UFO with an XLR connection does is use a transformer to turn the + and - phases of a balanced signal into a single ended signal (same thing a ZBIT does), which is what gets amplified. What the standard amp with the special cable does is use the L and R channel of a stereo amp to amplify the + and - phase of a true balanced signal. In theory you could replace the L and R RCAs with a XLR to make it look like a "regular" balanced mono block, but that is only a cosmetic change, the internal wiring in the amp would stay the same.

That may very well leave you more confused then when you started, but that's what I've got.

Title: Re: UFOs as Balanced Monoblocks?
Post by Brian on 09/18/20 at 10:04:09

I thank you James, for the education.
How would what you are doing sound different from the UFO2 with the XLR connection?

Brian

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 09/19/20 at 03:03:08

Beyond two to three times the power I can't really speak about Decware amps because I've never heard one. But in my experience balanced is just better. Better detail, better imaging, better dynamics and less noise.

Title: Re: UFOs as Balanced Monoblocks?
Post by Brian on 09/19/20 at 05:21:54

That sounds splendid.
Thank you, James.

Brian

Title: Re: UFOs as Balanced Monoblocks?
Post by Brian on 09/21/20 at 04:35:48

I read the Wikipedia article on Balanced Audio. The paragraph titled "Internally Balanced Audio Design" says:
"Most audio products (recording, public address, etc.) provide differential balanced inputs and outputs, typically via XLR or TRS phone connectors. However, in most cases, a differential balanced input signal is internally converted to a single-ended signal via transformer or electronic amplifier. After internal processing, the single-ended signal is converted back to a differential balanced signal and fed to an output.

A small number of audio products have been designed with an entirely differential balanced signal path from input to output; the audio signal never unbalances. This design is achieved by providing identical (mirrored) internal signal paths for both the "non-inverting" and "inverting" audio signals.

In critical applications, a 100% differential balanced circuit design can offer better signal integrity by avoiding the extra amplifier stages or transformers required for front-end unbalancing and back-end rebalancing. Fully balanced internal circuitry has been promoted as yielding 3 dB better dynamic range, though at increased cost over single-ended designs."

This internally balanced circuit sounds like the Decware preamp model ZTPRE.
This has me wondering: Can a Power Amp be made internally balanced, instead of internally single ended with balanced connectors on each end?
I think it would require twice as many parts, including the tubes; so double the price. But would the benefits for a power amp be the same as they are for a pre-amp?

Brian

Title: Re: UFOs as Balanced Monoblocks?
Post by CAJames on 09/21/20 at 15:37:34

Quote:

Can a Power Amp be made internally balanced, instead of internally single ended with balanced connectors on each end?

That's exactly what using a UFO as a balanced mono amp is. Using the L and R channels for the inverted and non-inverted phases. My current amps, (Pass Aleph 2) are also internally balanced. It might not be as rare as Wikipedia implies in the "high end" but it does take twice as many parts, and is more expensive.

Title: Re: UFOs as Balanced Monoblocks?
Post by Brian on 09/22/20 at 05:10:07

Thank you, James.
It is good to read that a power amp can be built this way.

Brian