[jules]

ok, maybe I should take this over to Audio Circle fight club but I want to have a go at monos . Please, don't get over emotional about this, I'm slightly tongue in cheek but at the same time .....

Why? why? why? Now I realize that 40 years ago as valve sound systems moved forward from being mono to being stereo, the first step was simply to use two separate units instead of one. So why, all this time later are people not only designing new monos but sawing perfectly good combined units in half???

To me, this is just poor design. There is no reason why two channels should not be in the same box. If hum is a problem then the layout or shielding is wrong.

I noticed a bloke from NZ suggesting that he was intending putting together an integrated amp. Yes, I know, shocking isn't it, all in the one box but I have to say ,Yea, great idea   less plugs, shorter leads and something you could move without taking half a day to re-assemble. I do realize that an integrated amp/preamp would cut down on the possibilities of fiddling with the system but maybe that's not such a bad idea. Less time to fiddle with plugs, more time to party   !

Jules

[andyr]

... 40 years ago as valve sound systems moved forward from being mono to being stereo, the first step was simply to use two separate units instead of one. So why, all this time later are people not only designing new monos but sawing perfectly good combined units in half???
 ...

Jules,

No, there's absolutely no reason why "two channels should not be in the same box" for a stereo amp.  But then what would you call my AKSA amps ... as I have 3 channels in a box, for my active setup?

The fact that each amp module has its own power supply, right down to its own switch and mains cord, leads me to call them "6 monoblocks" rather than "2 3-channel amps" - ie. it's the non-shared power supply which is the basic feature of a "monoblock", not the fact that there's only one channel in the box.

Regards,

Andy

[kyrill]

Ok Jules my 2 cts

reason for 1) 2 monoamps and 2) separate pre amp

In a mediocre not so transparent system an integrated amp has only (non musical ) advantages. cheaper to build, no expensive or cumbersome interconnects. easy to transport less powercords. Do you see all those advantages has nohing to do with sound.
Except shorter leads? Yes, they can be more musical
But those subtle musical advantages ( I am not talking about very long not shielded interconnects and wrong matching of impedance or crazy cables with too much capacitance, then the differences are not subtle) need a verygood transparent amp. And then putting everything in a box needs a lot of extra corrections. Becauce the more tranparent a system becomes, the more sensitive it will be. And not only to minute differences in the musical signal but sensitive to everything else which happens in the local physical domain. There will always be interference. The more sensitivity the more interference will cloud the musical tranparency in a very bad way.

So in a high end tranparent system you have to minimise interferences, that will be inaudable and harmless in a mainstream hifi system.
Not only good shielding to rfi and EMI  but good mechanical damping too(so you need mass, the best damping device, next to lightweight kind of "rubber"substance damping or with springs and so on
You need to protect against power supply electrical interference (power line conditioner) and channel interference. The best protection is distance. Protect circuit A from circuit B by keeping them physical apart and have all power circuits having their own power supply with dedicated own transformator. That keeps them electrical apart Magnetic fields interference  lessens quickly with distance too.

To keep interference low is possible but much more expensive and hard to acquire in one box, components cramped to each other. Everything pre/preamp and amp and all channels in one box has no practical musical advantages over the much bigger disadvantages. The reason you see one box components are always for economical reasons
Another disadvantage of one box is longer speaker cables. in a reasonable big room that is a disavantage realtive to short lenghts of less than 2 feet.

You even have to get rid of the pws in the box of the amp.. They need a seperate box too
But only if you want to have the best listening experience of course

Andyr
I too have three pwr amps in one box, but it is not a fair comparison as they do not cover the same spectrum and are from the same channel and yes, even to shield them from each other will be better. That is why I have put the power amps outside the box and all three have their own transformer

[jules]

Andy,

I don't want to get too bogged down in terminology here. A standard Aksa 55 or 100 has separate transformers etc and is of dual mono form. What I am having a gentle jab at is the idea of splitting something that doesn't really need to be, and adding unnecessary complexity by making something that could be uni-cased, bi-cased.

I am also, most certainly not attacking anyone's personal systems and I'm not trying to set any rules. As far as I'm concerned diversity and experimentation rule!  Bi-amping, tri-amping and other experiments aren't going to fit in any standard case so the logical thing is to use whatever seems most practical.

The reason I made the comment about the bloke who is thinking about an integrated amp/pre-amp [and I am presuming fairly standard forms of both] is that while this is a totally unfashionable approach it has some great virtues and presents a challenge to produce carefully thought out design rather than make it easy by the "many blocks" approach.

I am not suggesting that there should be such a thing as an integrated GK-1 pre/Aksa100N+ power, amp but it is interesting to think about and it would have the advantage of doing away with a whole set of interconnects [and we all know how horrible they are don't we!!].

There's no point in trying to cram something into the smallest space possible just for the sake of it just as there's no point in trying to split something into as many parts as is possible. If I did want to make a serious point here [and it's still not immutable] it's that design should be functional first.

Jules

[jules]

kyrill,

your reply came in as I was composing mine so I didn't see it till after I'd posted. I'll respond.

edit: I'm not saying that there are no situations where it is appropriate to use multiple cases. What I am suggesting is that multiple cases should not simply be used for the sake of it.
   
   [ I would suggest that it is possible to put say the GK-1  and a 100N+ in the same box successfully and that part of the problem is not so much the tech issue as one of conservative thinking BUT this is a separate issue to the point I raised initially about splitting a dual mono into two boxes]

Jules

[Rhythm Willie]

I procrastinated for some time on whether to go dual mono. I did go mono in the end and am glad I did.

It is debatable whether mono amps have better channel separation(mine have separate mains leads going to separate mains outlets). Some "experts"(John Risch) reckon that pidly 18gauge mains leads inhibit dynamics & bass.

Mono enabled me much more flexibility in designing the layout so that sensitive input leads & signals could be routed well away from 240v and speaker leads and it also made it easier to shield the power supplies from these inputs and amp circuit boards.  The amps have absolutely no hum or noise and quiet passages seem very black/silent.

The other advantage is very short (tri wired)speaker leads which seem to increase dynamics of the system.

[Al Garay]

I second Rhythm Willie's post.

Al

[DSK]

Some "experts"(John Risch) reckon that pidly 18gauge mains leads inhibit dynamics & bass. ...

Um, OK ...so use a heavier gauge AC lead     ...Not saying there aren't reasons for monoblocking, but this aint' one of 'em.  

[Rhythm Willie]

"Um, OK ...so use a heavier gauge AC lead  ...Not saying there aren't reasons for monoblocking, but this aint' one of 'em. "

Agreed, it was just a side issue/comment that thicker leads are'nt so important when theres two of them carrying half the current each.

[ginger]

Just to take up Rythm Willie's point on wire guages. Mostly talking power supply, mains leads amd speaker wires here.

Choose wire guage ALWAYS to be able to handle the full source current capability.
So what are the ratings of various wires - you'll find a heap of contradictory info around the web.

These are the 100 degrees C derated, bundled wires, capabilities we specify for Mil Spec jobs in my work. That is they are conservative ratings.

26 AWG - 1.5 Amps
22 AWG - 5 Amps
20 AWG - 7.5 Amps
16 AWG - 13 Amps
12 AWG - 23 Amps
8 AWG - 46 Amps

Mains Wiring - use 16 AWG
Speaker Leads (within the amp) - use 16 or 12 AWG
Between Power Supply and Amp Board - use 16 or 12 AWG

I use 12AWG for these last 2.

I keep 22 AWG and 16 AWG in various colours "in stock" in my workshop and buy 12 AWG when I need it.

There - more crap for your file of useless information.

Cheers,
Ginger

[kyrill]

double post

[kyrill]

... is not so much the tech issue as one of conservative thinking BUT this is ...

ahhh here I disagree.
Conservative thinking doen't mind interference which you should not hear.
Before jitter in digital land was "discovered" conservative thinking could not hear it. And all those "idots" like Harry Pearson and me (to be honest) who dare to say that cd was sounding MUCH more worse than LP's were in fact idiots.

And now with much more transparent systems it is the opposite way of "conservative thinking" that proclaims that mechanical and elctromagnetic interference is the killer of magic in listening experiences. Conservative thinking does not even acknowledge the existence of this "magic"
For instance also conservative thinking puts the quality of the power from the wall in the last place or no place at all while theoretically it should be in the FIRST place.

Unless I got you wrong Jules as I am not a native English speaker

[jules]

ok ... so let me suggest a theoretical set-up and I'm suggesting this an exercise in what is possible and certainly not as a criticism of what others have done:-

The cost of a box and the various extra plugs/interconnects needed can easily make up 1/3 of the total cost of a system [here I'm thinking three boxes, three sets of anti-vibration legs and various lengths of interconnect]. So, if you use one box instead of three you can save a significant amount which could be used to make a single advanced box.

So, two layer box ... 4 transformers in the bottom layer, probably at each corner [and possibly power supplies though I ask for your suggestions as to the advisability of this] ... above this layer a metal screen of some form [and this can be quite cheap] which is supported peripherally by a frame. The second layer can float on a complete structure supported by light springs on the same frame [this would be easy to do and the springs would be cheap, certainly cheaper than proprietary legs].  In the second layer you have all items that are sensitive to either vibration or elctro-magnetic interference. Great care should be given to spacing so that there where there could be a problem you have say 5cm. or whatever is really necessary. [There's no point in having a 10cm gap where a 1cm gap is quite enough but this is a question of knowing what is needed rather than guessing]

The whole box would stand on some form of anti-vibration feet. Internally there would be enough space [and it's more three dimensional than a single level case which helps] to move things around to achive short leads and appropriate spacing]. Separate 240V inlets are of course possible. The use of two different forms of suspension [springs and legs with different frequency damping characteristics] actually provides better damping than three separate boxes on similar legs. Short signal leads and well thought out layout could be totally hum free.

I reckon there's actually great  scope for an interesting looking design here because the tubes in the pre-amp can be used visually as well as the heat sink fins in the power-amp along with the various controls and leds.

I can see that this will make the distance to the speakers slightly longer [but only if the separate monos were not stacked with the amp and the former is a space consuming arrangement] and while there might be pros and cons both ways I can't see that either can be described as definitely superior.

jules  

[kyrill]

..The cost of a box and the various extra plugs/interconnects needed can easily make up 1/3 of the total cost of a system [here I'm thinking three boxes, three sets of anti-vibration legs and various lengths of interconnect]. So, if you use one box instead of three you can save a significant amount which could be used to make a single advanced box.
True, but cost advantages belong to a very different world then musical advantages
On the other hand, wooden boxes or mdf/plywood boxes are very very cheap to manufacture

So, two layer box ... 4 transformers in the bottom layer, probably at each corner [and possibly power supplies though I ask for your suggestions as to the advisability of this] ... above this layer a metal screen of some form [and this can be quite cheap] which is supported peripherally by a frame.
The second layer can float on a complete structure supported by light springs on the same frame [this would be easy to do and the springs would be cheap, certainly cheaper than proprietary legs].
not easy at all. Every spring has its own characteristics and damps a certain freq band completely depending also on the weight it has to damp.
In the second layer you have all items that are sensitive to either vibration or electro-magnetic interference. Great care should be given to spacing so that there where there could be a problem you have say 5cm. or whatever is really necessary. [There's no point in having a 10cm gap where a 1cm gap is quite enough but this is a question of knowing what is needed rather than guessing]
One box will be very heavy. And if you take all this trouble to go for the best, forget toroïd transformers They were invented for space and weight reasons. THey should broadcast less magnetic fields, but which can be counter acted by space or shields, but, as also Hugh pointed out, much heavier EI type (old fashioned) transformers are less prone to pick up high freq interference and (should) sound cleaner

The whole box would stand on some form of anti-vibration feet. Internally there would be enough space [and it's more three dimensionalthat is up to the designer than a single level case which helps to move things around to achive short leads and appropriate spacing]. Separate 240V inlets (never understood the advantages of this approach are of course possible. The use of two different forms of suspension [springs and legs with different frequency damping characteristics] actually provides better damping true than three separate boxes on similar legs.That is up to the designer as well, however springs are good for a LP platter, but for amps?  Short signal leads and well thought out layout could be totally hum free.
Of course it is possible. But practical? It reminds me of Japanes thinking. The Japanese are technically VERY open minded. Think of the SONY phono player with an integrated electronic steered FB motor mechanism in the arm (!) of the pickup to balance out the vibrations by inducing "counter vibrations" 180 degrees out of phase.
The Western world of thinking produced very balanced light weight passive arms (the SME for instance


I reckon there's actually great scope for an interesting looking design Yes, I agree, but different realm again, also beauty is separate from musicality here because the tubes in the pre-amp can be used visually as well as the heat sink fins in the power-amp along with the various controls and leds.
naked (read see-able)  tubes pick up loads of interference


I can see that this will make the distance to the speakers slightly slightly is only valid in a (very) small room longer [but only if the separate monos were not stacked with the amp and the former is a space consuming arrangement] and while there might be pros and cons both ways I can't see that either can be described as definitely superior.  ...

We all have our own meaning, I am very happy with that That said, one box advantages are economical, not for musical reasons. With wooden boxes not even economical. Unless you like to buy over expensive inter connects or shun away from building your own, often superior interconnects

[jules]

Kyrill,

I don't want to go round in circles here and naming a thread "monoblox sux" just might have been slightly provocative of me but the main point of my "design" post was to encourage input on possible ways to have a pre-amp/amp in the one box so as to equal or even better what can be achieved using three separate boxes. So, to keep this from becoming too rambling can I reply briefly in point form:-

  * replacing half a metre of interconnect, a pair of male and a pair of female RCAs (or sim) with maybe 50mm of wire direct soldered at both ends is a significant gain whatever way you want to look at it (ask Malcom Fear). The cost saving is secondary.

  * springs aren't all that mysterious. I would suggest a set of maybe six 30mm diam light coil springs with a loaded harmonic frequency of well below 50cps. In conjunction with a set of anti-vibration legs this would act somewhat like a car suspension with a spring/damper action.

  * Yes, the box would be heavy but mass is an aid when it comes to countering vibration. [the issue of transformer type a separate matter]

  * I was not proposing that the tubes should be "naked". Although I like that look I think there's other ways to show the presence of tubes.

  * This is not an exercise in over-engineering (as in the Sony arm you mention). It's actually an attempt at simplification. The boxes are simplified. The wiring is simplified and even the springs, while unconventional, would not be hard to implement.

  * The potential for exciting design possibilities that I mentioned would follow from the layout [rather than being a driver of the layout as I think you are suggesting. I seem to remember a post you made that supported this approach]

Finally, I'm not really trying to get into a debate here. Maybe this thread should be combined with the concurrent one on having a TLP and an Aksa 55 in the one box. PSP had a go but was brought down by hum. DrDave had success and SamL is about to have a go. What I'm interested in is a sort of "what if" discussion that explores possibilities. Convention can be limiting. My overview of what you have said is not that my design wouldn't work but more that it is unconventional.

On working in three dimensions can I say this:- Most boxes are two dimensional. This is easy to work with because of its simplicity but also limiting [as we all know given the limited no. of ways that transformers, heat sinks, power supplies and interconnects can be arranged in a standard box]. You can't just lay stuff out on the bench in a 3D way so this really has to happen in your head first [and that makes it hard to test]. In layout terms its got great potential through flexibility to keep leads short and offer more options for component arrangement.

Separate monos are a simple solution to a problem that has become the accepted convention in high end audio. There are compromises in both multi box and uni box arrangements. Why not explore the possibilities here? I remember a very entertaining thread that included input from Hugh on a design that used trained spiders to produce a sling for an amp that floated on a mercury bath  . I believe that what I proposed was quite achievable but any form of creativity is worthwhile.

jules

[DSK]

Onya Jules ....go for it I say! If you come up with a design that provides significant sonic improvement, I'm sure there will be a flurry of activity from other AKSA owners following your lead  

* Yes, the box would be heavy but mass is an aid when it comes to countering vibration. ...

 From what I have read, this is only true if the added mass provides added rigidity (at least  in regard to equipment racks), or it is done for a specific purpose (eg. matching load to the rating of mechanical or air springs).

[jules]

 wot, another amp? I've only just recovered from making my 55N+ and while I have huge admiration for the [self described] quixotic efforts of ginger and others I'm fully expecting my amp to be so perfect that I will never ever have to build anything more   .

On the issue of mass; a single box would of necessity be more rigid. It would presumably have different acoustic properties though this is the point where an acoustics engineer should appear magically with some facts. I'm not all that concerned about vibration myself but if it is an issue then I reckon the plan I put up does a great job of addressing it in a simple though unusual way.

As to your tongue in cheek suggestion of a flurry of activity ... I rather doubt it. Even if such a project was 100% successful it would still be considered improper. Failing the detection of any audible vibrations it would be deemed sensitive to some newly discovered particles with a penchant for attacking things in one box; that or the vibes from that person next door   .

jules

edit: I'm going to be using my 55 [initially at least] with an inbuilt passive pre-amp in the form of an Elma ladder. This isn't quite the same as the proposals above but it is technically "all in one box" and does show how totally sincere I am doesn't it?

[mikenz]

Hi Jules

I've done something similar to what you are talking about with my 100 N+:
http://www.audiocircle.com/image.php?id=4490

I was more pleased with a passive pre over the GK-1 with my setup, so I've integrated a DACT input selector and attenuator in a subenclosure at the rear with shafts from the control through to the front panel (not shown in pic). It didn't seem logical to have a seperate box for the passive pre with all it's extra wiring, connections etc. I've also put the PS board and the transformers in a sub enclosure within the same box.

My thinking was similar to yours - hardwired interconnects eliminate extra plugs and wire length, all wiring is very short including ps to amp and trafo to ps. I also like the simplistic approach. I'd rather have a one box solution than a multibox solution if it doesn't sound better.

When considering how to mount the amp I toyed with the idea of a seperate power supply box, however I thought that if the boxes were stacked on top of each other, the isolation between the two boxes of a 1.5m top panel of the bottom case and the same for the bottom panel of the top case the amp and the ps would be very similar to having a divider in the same box - without extra connections in the power wires, longer lengths - increased cost trying to find a suitable connector for the power. To that end I decided to go 3 in 1 box with 4mm aluminium dividers.

Although I dont have a differently mounted aksa hear to compare, I can say for certain it sounds significantly better than when I was running it with no case spaced out across a table. I'm not sure what has given the gains, probably a combination of things.

[Rhythm Willie]

mikenz,

What a fantastic layout. IMO one of the best I've seen - you must have put a lot of thought into the design of the case,layout & screening. IMO this is extremely important to maximise the potential performance of the AKSA's. You layout is exactly what I would have done. PS where does the 240V mains come in?

FYI I also put a fair bit of thought into my Monos that I built early last year.

I am currently upgrading to plus version and am also thinking about adding passiveattentuators at the signal inputs.

http://au.photos.yahoo.com/ph//my_photos

[mikenz]

Thanks for the nice feedback.

The mains wiring entry was one of the harder things to overcome - as I really wanted it entering the back, but Hugh had a great recommendation of running it through some metal tube, which is earthed - getting rid of any nasties. I am running two mains cables, so they just run under the amp boards hard against the heatsink. I'm not sure if two mains cables makes any difference, but it's just as easy to have two and I dont see any disadvantage.