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Mono operation (Read 6692 times)
TerribleTed
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Mono operation
01/27/09 at 15:40:56
 
Trying to find out how to hook these up in mono.  I don't see any details in the manual but as I recall, a Y connector is installed and connected to both inputs while a jumper wire is placed from the positive on one speaker connector to the common on the other side to make a series connection.  Is this correct?  The two amplifiers are a SE84CS and a SE84C+ which I assume are both connected in the same fashion, correct?  What should I expect other than increased power?
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Steve Deckert
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Re: Mono operation
Reply #1 - 01/28/09 at 14:16:03
 
Hi Ted,

Yes, that is correct.  You'll get an additional 6dB before clipping and a greater sense of weight.

Steve
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TerribleTed
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Re: Mono operation
Reply #2 - 02/23/09 at 21:00:22
 
Yes, it does have significantly more weight and volume.  Sounds very good and handles inefficient speakers quite well in mono.  Is it just my imagination or do the amps run a little warmer in mono?
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Miles
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Re: Mono operation
Reply #3 - 02/24/09 at 01:50:04
 
Ted I recently bought a second SE84C and now run them as monoblocks wired in series to drive Decware MG944 speakers. This change was a huge improvement to my system. Yes, more weight and control. You can easily modify your amps yourself by opening the case and soldering in a shorting wire between the inputs thereby obviating the need for "Y" interconnects.

Can't say they run hotter than before but did notice a significant increase in hum (approx. 2X) though I do not hear it from the listening position.

Regards, Miles
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Coherent Sound
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Re: Mono operation
Reply #4 - 01/27/10 at 03:14:38
 
Steve,

I just got my new SE84C+ with CCE and so far it's great!  More comments on that in another post.

I may get another and put them in series.  Could you put some detailed instructions in the manual on how to do that?  Not only informational, but perhaps a selling point, for new owners who might want to do that.

Thanks!   Smiley

Gary
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Coherent Sound
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Re: Mono operation
Reply #5 - 01/27/10 at 03:48:46
 
Hi again,

A comment about "more weight".  My current system consists of my new-as-of-yesterday SE84C+, a Pioneer Elite SACD/DVD player, Paul Speltz anti-cables, Paul Speltz anti-interconnects, and Klipsch Forte II speakers (99dB efficient).  

I have one particular CD I like for string sound - Igor Kipnis playing Scarlatti Sonatas on the harpsichord.  When I played that CD yesterday it sounded small, even at full volume (CDs are recorded at different levels I guess) and the sound didn't hit me nearly like it did when I had hooked up my CJ PV-12 preamp and Adcom GFA-565 monoblocks.  

However the Forte IIs are 8-ohm speakers and the SE84C+ loves 2-ohm speakers according to the manual, and not 8-ohm so much.  What to do?  I hooked up my trust Paul Speltz Zero Autoformers between speaker and amp, wired so as to *reduce* the impedance by a factor of 3 - essentially changing 8-ohm speakers into 2.66666 ohm speakers.  

What a difference!  The SE84C+ puts out more power at lower impedances, and the weight is back in the sound and I'm very happy with what I'm hearing now - and the amp has barely been broken in.  I asked Steve about the Zero Autoformers before I got my amp, and he advised me to try it without the Zeros first.  I did and then tried with the Zeros, and they work wonders.  At the current price of $450 a pair they are not cheap, but you might consider it if you have higher impedance speakers.  They can be used to either lower or raise speaker impedance, with lots of different multiplying factors, depending on how you hook them up.  No, I don't work for Paul but I really like his stuff.

After a while I'll switch them around so they are only a 2/1 drop in impedance, making my Forte IIs like 4-ohm speakers to my SE84C+ and hear what that sounds like.  Kind of like tube swapping - the new hookup really has a different sound and feel.  

BTW, I have owned Atma-Sphere OTL tube preamp and monoblock amps, and I sold them because I didn't "feel" the music.  Clean and nice, but not all there.  I have to say that already, after only a day Decware blows them away.  

I also have a ClearAudio Emotion turntable with Benz Ace MC cartridge, which I'm not playing now because I need a good phono preamp (My CJ PV-12 preamp has a built-in phono pre), so of course I'll need a Decware ZP3 with MC step-up transformer.  And then perhaps a ZCD CD player, as well as full range speakers (eventually), but for now I'm really liking what I'm hearing, a LOT.

Thanks Steve!

Gary
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Forget about distortion-free sound. All sound is distortion. If one seat at a live performance sounds different than another, what is the "original" pure sound? There is no such thing. In the end all that matters is, what kind of distortion makes you smile?
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Coherent Sound
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Re: Mono operation
Reply #6 - 01/28/10 at 05:17:08
 
Hi again,

A follow up - I just switched my Zero autoformers so that my 8-ohm Klipsch Forte IIs look like 4 ohms to my now 3-day old SE84C+ and it's even better than when I had the autoformers set to 3/1 (2.6666 ohms).  I think the 3/1 reduction in impedance wasn't quite the right combination but now the 2/1 ratio seems a good balance between more weight and smoother, solid sound.  The 3/1 was a bit grainy and forced compared to what I'm hearing now.  I noticed this difference right away when I switched connections so it's more than just the amp being another day broken in.  Instead of just tube swapping, speaker swapping hehehe.

Again, kudos to Steve and all the Decware crew.

Gary
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Forget about distortion-free sound. All sound is distortion. If one seat at a live performance sounds different than another, what is the "original" pure sound? There is no such thing. In the end all that matters is, what kind of distortion makes you smile?
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ski bum
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Re: Mono operation
Reply #7 - 02/27/10 at 21:11:40
 
Steve (or anyone else)-

When strapped in mono is it still considered 'single ended'?  This is kind of academic, I guess, but I'm curious.  

Also, how do the extra output trannies and tubes affect the amp/speaker relationship?  I know that the amp will see half the rated impedance, but is damping factor or other aspects changed?  Why does series wiring of output 'maintain transparency' over parrallel, as per the manual?  

Relatedly, if your amps are seeing half the impedance, does that also mean that any peaks or dips in the impedance are also reduced, thus giving a smoother, easier impedance curve?  Does this benefit the sound?

Just how much do impedance irregularities affect response?  Using my rudimentary test gear, my wacky impedance speakers driven by zens produce remarkably flat in room response (once above the bass node zone, ~150hz or so, pretty freakin flat to beyond 16k, where I stopped).  I have been told that single ended amps always produced a response that reflected the impedance of the speaker being driven.  What's really going on here?

Do you really get more noise when the amps are bridged?  (I don't in my system, but perhaps I'm just lucky...speakers aren't ultra efficient so may mask residual noise.) 

Thanks in advance for any answers to these questions!

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« Last Edit: 02/27/10 at 23:32:15 by ski bum »  
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Lord Grumble
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Re: Mono operation : how to?
Reply #8 - 06/21/12 at 17:14:08
 
I have ordered 2 SE84+ amplifiers to use them as monoblocks.  I am very anxious to receive them (probably in August).  I have read the posts in this topic and others  but I am really a novice in this area.  The first poster wrote :

Quote:
Trying to find out how to hook these up in mono.  I don't see any details in the manual but as I recall, a Y connector is installed and connected to both inputs while a jumper wire is placed from the positive on one speaker connector to the common on the other side to make a series connection.

The first part about getting a Y connector seems easy to realise.  Should I get however good quality connectors or will ordinary ones suffice?

The second part is a mystery to me (sorry if this makes me an amateur but that's the truth).  What kind of jumper wire should I use?  Are these jumpers available on the market or should I make them myself?  Are there any instructions in the actual user's manual related to this?

Thank you for your input on this.

Lord Grumble
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Lon
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Re: Mono operation
Reply #9 - 06/21/12 at 17:17:33
 
Lord,

Couldn't you ask Steve to wire them as monoblocks? Should be easy.
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Lord Grumble
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Re: Mono operation
Reply #10 - 06/21/12 at 17:43:57
 
Yes I thought about it but, in a way, it will definitely transform the SE84+ into a monoblock.  I will not be able to use each one as a stereo amplifier.  I am still undecided about that.

If customizing each amplifier into a monoblock is a better technical (and musical) solution, then I'll probably do it.  I would have to be certain that it is the best solution (musically speaking).

Thank you for the suggestion.

Lord Grumble
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Lon
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Re: Mono operation
Reply #11 - 06/21/12 at 17:51:16
 
To my way of thinking it would be the most musical solution, as even the highest quality interconnect is still a few more pieces in the chain that wouldn't be there if the internal wiring were used. Whether you could hear the difference with the highest quality might be debatable, but I bet you could with lower quality, and you could save yourself that expense. Steve would have the best advice.

It would mean you'd have to have them rewired for stereo, yes. I think if you plan to use them as monoblocks that may not be a big issue, and you could probably sell them rather easily as a pair of purpose built matched amps as well if you decide to, or have them rewired as stereo and warranty revamped. . . .
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ZYGI
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Re: Mono operation
Reply #12 - 06/21/12 at 22:58:45
 
Seeing as it only take shorting the two positive leads at the inputs, a switch could be installed, switching between mono and stereo operation would be a simple task.

As far as wires at the speaker terminals, I'd use what you plan to use for speaker wires, keeping that all the same.

Just a thought....

Zygi
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Lord Grumble
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Re: Mono operation
Reply #13 - 08/31/12 at 21:41:57
 
As previously mentioned in this topic, I have ordered 2 SE84C+ in order to use them as monoblocks or to bi-amp my loudspeakers.  I feared that one SE84C+ would not be powerful enough for me.

Well I was wrong...  I have received both amps and have yet to use them at the same time.  One is more than enough to "power" my loudspeakers (Triangle Antal SE, 92 dB sensibility).  I listen to classical music, jazz and quite a bit of rock (Beatles and Beach Boys mostly, but also punk music circa 1978, that should indicate my age... Smiley) and, when I decide to listen to loud music, the SE84C+ is up to the task.  I have yet to hear it clipping (whatever that is).

Now what do I do with my spare SE84C+?
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sberger
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Re: Mono operation
Reply #14 - 09/01/12 at 04:56:15
 
First thing I'd do is try that second amp out in the system. You may end up finding that combining them bring extra dynamics with the added power. In any event doesn't make sense to order them, endure the wait, and then not at least try them both before making any final decisions.
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