stereo amp vs. dual monos

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cementhead

stereo amp vs. dual monos
« on: 1 Apr 2015, 02:41 pm »
 Thinking of upgrading my modified Khartago to dual monos.Looking for opinions/sound differences/ benefits between a stereo amp and dual mono amps.

GentleBender

Re: stereo amp vs. dual monos
« Reply #1 on: 3 Apr 2015, 07:37 pm »
Wow! It's been pretty quiet around here lately. I was watching this thread to see what opinions were going to be. I'm thinking better separation, but it is only speculation on my part.

Charles Calkins

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Re: stereo amp vs. dual monos
« Reply #2 on: 3 Apr 2015, 08:00 pm »
I tried mono amps and a stereo amp to drive my VSA speakers and couldn't hear any difference. Six of one.half dozen of the other.
 I finally settled on a Mac 352 stereo amp. Good enough for me.

                                            Cheers
                                            Charlie

cementhead

Re: stereo amp vs. dual monos
« Reply #3 on: 3 Apr 2015, 08:57 pm »
yea, where are the dual mono owners here? maybe I'll be keeping the stereo amp after all. :)

Haoleb

Re: stereo amp vs. dual monos
« Reply #4 on: 4 Apr 2015, 12:41 pm »
You are asking a pretty subjective question... wondering if it will be worth the expense to go from your current stereo khartago to the mono's. Regarding that it is up to you.

I have a pair of khartago mono's, I have always been a fan of dual mono amplifiers (two complete amps one box) and mono amplifiers. One amplifier, One power supply, one chassis for one channel. With my 2.2 setup I have 4 amplifiers. Overkill? I'm certain it is but so what.

As far as channel separation goes, chances are your preamp and source is not dual mono so having the power amplifiers being mono is likely a moot point.

All that being said. If you got the cash kicking around to do the upgrade i'd say go for it  :thumb:

GentleBender

Re: stereo amp vs. dual monos
« Reply #5 on: 5 Apr 2015, 10:48 am »
As far as channel separation goes, chances are your preamp and source is not dual mono so having the power amplifiers being mono is likely a moot point.

Thanks for your input, I hadn't even thought of that detail. Things could get a bit complicated and expensive for wiring and space for all the separate components.  :icon_surprised:

sebrof

Re: stereo amp vs. dual monos
« Reply #6 on: 5 Apr 2015, 12:18 pm »
Thanks for your input, I hadn't even thought of that detail. Things could get a bit complicated and expensive for wiring and space for all the separate components.  :icon_surprised:
Keep in mind mono amps generally go behind the speakers. Mono amps actually solved a rack space problem for me.

Early B.

Re: stereo amp vs. dual monos
« Reply #7 on: 5 Apr 2015, 12:38 pm »
I'd like to read about someone doing an A/B test between monos vs. stereo of Odyssey amps. It would be interesting to see if the reviewer could determine the sonic differences.

jdoris

Re: stereo amp vs. dual monos
« Reply #8 on: 5 Apr 2015, 01:53 pm »
For several years, I had a Stratos Dual Mono I really liked, though I didn't compare it to other configurations.  Two of everything, including on/off switch and PCs, but one box.  Maybe best of both worlds, rack-space wise?  Worth seeing if Klaus still builds 'em.

John

barrows

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Re: stereo amp vs. dual monos
« Reply #9 on: 5 Apr 2015, 03:46 pm »
As long as an amplifier uses dual mono circuitry internally, and the layout is decent, there will be no difference in Mono Block vs, single chassis designs.  You can check this out for yourself by looking at the measurements for channel separation for various amplifiers at stereophile.com.
In many cases, even a dual mono amp sharing a single power supply will also be as good as Mono Blocks (this will depend on amp topography and design).
And, since chassis and transformers are the most expensive part of any amplifier, Mono Blocks will also cost much more for a given performance, and require another power cord.
If one is looking to improve system performance, going to Mono Blocks is about the last place I would consider, as the price to performance benefit ratio is not in your favor.

maplegrovemusic

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  • Please Be kind to your ears .... Treat your room
Re: stereo amp vs. dual monos
« Reply #10 on: 5 Apr 2015, 04:00 pm »
Another benefit is the short speaker wires one can use when placing the mono's behind the speakers . As short as six inches can be used . When buying speaker cables one can buy jumpers instead of 8' . A nice cost savings .

cementhead

Re: stereo amp vs. dual monos
« Reply #11 on: 5 Apr 2015, 05:05 pm »
Ah, Barrows. That's the input I was seeking. :thumb: I would think that people with the 2 amp set up have a reason/opinion to why they went that route as opposed to a stereo amp. As to improving system performance, the Kismet ref. monitors was the huge leap I was hoping for.I'll just save my money for the next upgrade,whatever that may be... 8)

klaus@odyssey

Re: stereo amp vs. dual monos
« Reply #12 on: 5 Apr 2015, 05:29 pm »
Time to chime in as the discussion goes wayyyy into the wrong direction here.....As for stereo vs. monos,  that is completely depending on the designs.....No idea as to the Mac's or other companies, but in case with the Symphonic Line designs,  and as such, very much so with our designs,  monos are VASTLY  superior to stereo amps....much,  much better in every single regard,  especially in terms of speed, (dynamics, micro areas), sound staging, presence, colors of timbre and on and on and on...mostly though because it also triples + the current delivery,  which really, truly gives you a frickin' hammer in these velvet gloves.  Much, much better,  as it should be, because yup, it's twice the money...I always tell people that in layman's terms with the monos being 100 % of sq, the corresponding stereo unit is only 40 - 50 % thereof.   As with everything else when comparing these two, one should also be aware of how to compare gear...always listen to the better (i.e. monos) first, and the "lesser" last, because physiologically, our brain and perception picks up missing quality much better than the other way around....

As for the Dual Mono amp, yes, I'm still doing a few here and there for special orders....main reasons why we discontinued them is because for one, they are a pain in the ass to make,  and secondly, we really have to have the customer's voltage down as there are now 4 output stages putting heat into the chassis...when set up right, it gets quite warm, never hot, but considering that all of our gear is running pretty cool,  I still don't like the idea as to a bias gone wrong with stepped up voltage...not a fan as correct bias is so dramatically important.

So, yes, monos are always better in our line,  considerably so, (just look at the TAS reviews of the upgraded K. stereo and the 5 year old stock Stratos monos,  with , when taking each board individually, the K. board was superior to the monos, and yes, it came damn close...I mean really close and near identical to the Soulutions), but again, that depends on each and every single design out there.......in general, one caveat in that I am NOT a fan of any designs that can be bridged into monos, not at all......and finally, as for the issue of short LS cables:  yup, great when you want to place them next to the speakers for aesthetic or real estate reasons,  but in general, I'd prefer shorter IC's and longer LS cables.....better information transfer especially with a high gain amp such as ours.....


Late,

Klaus

aaron.luebke

Re: stereo amp vs. dual monos
« Reply #13 on: 6 Apr 2015, 10:00 pm »
I've got one of each Stratos (I've lost track of how many pluses Klaus put in but black board, all the caps, but not the uber caps, most of the good stuff) dual mono chassis and straight stereo.  I've compared them (but backwards based on Klaus's recommendation) and I noticed channel separation and imaging was better instantly.   

I use the dual mono on the main speakers and the stereo on the subs.  If I find a bunch of extra cash I'm going to have Klaus build a set of true mono's for me but that's going to be a few years off (kids in college can burn through piles of $$).

If you've got the $$ to burn - go mono's!   :thumb:

*Scotty*

Re: stereo amp vs. dual monos
« Reply #14 on: 6 Apr 2015, 11:30 pm »
Klaus can these monos be built with 625VA toroids instead the 400VA transformers.
Scotty

klaus@odyssey

Re: stereo amp vs. dual monos
« Reply #15 on: 7 Apr 2015, 12:41 am »
yes

Tomy2Tone

Re: stereo amp vs. dual monos
« Reply #16 on: 7 Apr 2015, 12:49 am »
Klaus can these monos be built with 625VA toroids instead the 400VA transformers.
Scotty

What would the difference be and for what need? Genuinely interested.

*Scotty*

Re: stereo amp vs. dual monos
« Reply #17 on: 7 Apr 2015, 01:28 am »
The 625VA toroidal transformer is a little over 1.5 time larger in than the 400VA transformer and would lower the power supplies impedance by the same amount. This should net an improvement in dynamic life, bass control and greater solidity to images within the sound-stage. In addition it allows for more RMS power into a 4ohm load due the rail voltage sagging less when the amp is driving a 4ohm loudspeaker. Theoretically the amp could then double its power into a 4 load if it does not already do so.
 As with anything there is a point of diminishing returns past which making a transformer larger does not net an improvement worth the cost. With 110 watts RMS into 8ohms 625VA is about it. Much larger than this and you can start hearing the negative effect of the increasing wire gauge on the secondary transformer windings, the effect being that the amplifier can start to sound kind of dark from the mid-range on up. Bifilar secondary winding can help with this but the added expense to something already past the diminishing returns signpost is a great waste of resources that could be better applied to something in the amp that will make a very audible improvement.
 The other problem that can crop up is the larger diameter toroidal transformer also has a proportionally larger radiated EM field which can induce hum into the circuit of the amplifier.
Scotty

srb

Re: stereo amp vs. dual monos
« Reply #18 on: 7 Apr 2015, 01:55 am »
Curious as to why the Khartago Stereo and Mono amplifiers are both rated at 110W/ch, while the Stratos Stereo and Mono amplifiers are rated at 150W/ch and 180W/ch respectively.  All four amplifiers have a 400VA transformer and PS capacitance is 60,000uF for both stereo models and 120,000uF for both mono models.

All amps use the same transistors, although I imagine the power output difference between the Khartago and Stratos is the number of devices.  Just wanted to know why the Khartago Mono doesn't get the same 20% increase in power.

Steve

Tomy2Tone

Re: stereo amp vs. dual monos
« Reply #19 on: 7 Apr 2015, 02:19 am »
The 625VA toroidal transformer is a little over 1.5 time larger in than the 400VA transformer and would lower the power supplies impedance by the same amount. This should net an improvement in dynamic life, bass control and greater solidity to images within the sound-stage. In addition it allows for more RMS power into a 4ohm load due the rail voltage sagging less when the amp is driving a 4ohm loudspeaker. Theoretically the amp could then double its power into a 4 load if it does not already do so.
 As with anything there is a point of diminishing returns past which making a transformer larger does not net an improvement worth the cost. With 110 watts RMS into 8ohms 625VA is about it. Much larger than this and you can start hearing the negative effect of the increasing wire gauge on the secondary transformer windings, the effect being that the amplifier can start to sound kind of dark from the mid-range on up. Bifilar secondary winding can help with this but the added expense to something already past the diminishing returns signpost is a great waste of resources that could be better applied to something in the amp that will make a very audible improvement.
 The other problem that can crop up is the larger diameter toroidal transformer also has a proportionally larger radiated EM field which can induce hum into the circuit of the amplifier.
Scotty

Thanks for the explanation! I have 4ohm speakers and what you say here sounds intriguing.

Klaus...have you considered using 625va transformers before?