[Lost81]

Anyone tri-amping their speakers with their AKSAs?

I understand that you MUST have an active crossover in order to do it, yes?

I was looking at how B&W actually put their passive crossover in a box external to the speaker (better cooling under high volumes?), and am wondering if the same can be done for other speakers that are only set up for bi-amping.

That would be interesting, I bet.
A 25W AKSA N+ driving a 1" silk dome tweeter, a 55W AKSA N+ driving a 6.5" Aerogel Midrange, and a 100W AKSA N+ driving the 8" woofer.

I wonder though, what sort of wires would one run FROM the external crossover box to the the drivers themselves?


Cheers,
-Lost81

[PSP]

Well.... not right now, but I'm moving that direction.  It will take me a year or so to get everything built, but I intend to build clones of Jens' Equilibrium speakers (see  http://j-a-thorsen.homepage.dk/home_gb.html ).

I will use a 100w AKSA N+ for the bass (active XO at ~250Hz) and a 55N+ (passive XOs) for the mid and tweeter.  After that is running well, I may try putting a 25w AKSA N+ on the tweeter.

XO options are the classic speaker level passives, passive line-level XOs between preamp and the respective mid and tweeter amps, or active XOs.  Although active systems are sometimes derided for "all those op-amps"--and poor active executions abound--the glowing reports one hears regarding the Linkwitz' Orion and Phoenix suggests that it can be done well.

When I visited Jens in Denmark a year or so ago, I was completely blown away with his system (and this was before he had finished his GK-1!!).  I heard sweet music with incredible detail and high end extension (never a hint of harshness), heavenly midrange, and bass that was phenomenally tight, impactful, musical and absolutely right--this with no additional sub.  The music was absolutely balanced, integrated, uncolored... crisp and sweet like a nice white wine and--when called for--powerful like a punch in the stomach.  So, I will initially build Jens' system as he did:  active equalized bass and passive mids and highs.  I could listen to that forever, but I will probably eventually try carefully-built active XOs to see what that sounds like.

In any of these cases, I plan to build the XOs external to the speaker (less heat and vibration, easier to tweak, etc).  For wires, it would be possible  to optimize the wire for each frequency band... certainly the highs do not need the same current-carrying capacity as the bass does, so one might use a few strands of cat-5 or small guage silver in teflon for the highs and something more beefy for the lows.  So many options, so little time...

Peter

[andyr]

Anyone tri-amping their speakers with their AKSAs?

I understand that you MUST have an active crossover in order to do it, yes?

I was looking at how B&W actually put their passive crossover in a box external to the speaker (better cooling under high volumes?), and am wondering if the same can be done for other speakers that are only set up for bi-amping.

That would be interesting, I bet.
A 25W AKSA N+ driving a 1" silk dome tweeter, a 55W AKSA N+ driving a 6.5" Aerogel Midrange, and a 100W AKSA N+  ...

Yes, Lost81,

May Maggie IIIas are actively tri-amped - 25w for the ribbons, 55w for the mid pannels and 100w for the base panels.  They sound great!

My active crossover is a mono construction - ie. a crossover box sits behind each speaker.  My amps are all mono-blocks so, again, a box containing 3 AKSA modules sits behind one speaker, another box sits behind the other speaker.

The wires from amp modules to the drivers can be whatever you want - ie. get as fancy wrt cable as you want to be.  If you sit the amps right behind each speaker then you can have relatively short speaker cables.

Regards,

Andy

[AKSA]

Yes, Benny,

This is entirely practical, and as time goes on I intend to suggest ways of doing it which minimize pain of construction.  The AKSAs are made for this role, and in fact Ben Williams, aka Tinker, Aspen's digital designer, has done just this, with Seigfried Linkwitz's active crossover (arguably the most sophisticated analog crossovers ever devised for domestic hifi) and SL's Phoenix dipole speakers (which are sensational, a novel approach, very, very fast with astonishing micro-detail).

So, yes, a fruitful path.  In fact, the 55W is already small enough in width (a shade under three inches) that a couple of 25W and a 55W can be mounted on one heatsink!  I must admit looking back that during the original design I had this in mind, as I too, with some reservations, wanted to make the AKSA suited to multiamp configurations...

Thank you Peter and Andy for your informative posts.  I have certainly heard Andy's setup and I must say it is just sensational, and I'm not really a Maggie fan, but they are the best Maggies I've ever heard.....

Peter, Jens speaker does sound entrancing.  One day, one day.......

Cheers,

Hugh

[mb]

An AKSAphile in Singapore triamps his beautiful Linkwitz Orions with a stack of 100+55+55 IIRC. Stunning...

I use a bi-amp config (passive) where the mid/treble and bass cables are different. I believe there is a discernible difference when the top cables (own brew cross-connect) are swapped with the bass (DH Labs T-10). The top and bottom amps are also not symmetrical (55N and Rotel), but matched for sensitivity. Thus far there's no hint at all that having different amps causes any loss in tranparency. Each amp has been modded and optimised for this config, but every mod on the AKSA (mid/treble) seems to have inordinate positive effect on bass .

[Tinker]

That would be interesting, I bet.
A 25W AKSA N+ driving a 1" silk dome tweeter, a 55W AKSA N+ driving a 6.5" Aerogel Midrange, and a 100W AKSA N+  ...

Yup. Done almost this exact combo.
Audax HM210ZO, HM100Z0 (4", a very nice mid), and a Vifa Tweeter. Pretty sweet. Basically an active version of the KLS-9 project that once appeared on the Audax website.

As Hugh has said I run a Phoenix now with 3X55W. I have also run this using a number of tube amps and other SS projects. For transparency, musicality and punch the 55 rocks.

T.

[kyrill]

I have (probably mentioned in another post) the idea (vision maybe a better expression) of tri amping speakers with Aspen gear.

However active filters are not easy and contain their own can of worms, next to being expensive.

But when the DEQX came along suggesting to me from what I read from its properties, that tweaking and adjusting the filters to any kind of speaker combination could actually be done by a child of 10 years old, I dared to activate my vision.

SO I bought 2x 50 watts AKSA and 1x 25 watts AKSA all the N+ variant. Also 2 basic GK1-s not as an preamp, as this will be the DEQX (with the build in active digital filters) but as a luxury TLP , just to enhance the sound. For the bottom bass speaker I did not choose for a GK1 enhancer to lessen the costs.

Speaker drivers with the help of this forum, became a ribbon Raven like tweeter (Aurum Cantus G3) with a sensitivity of 100db/1watt. (too much AKSA 25, maybe an even better sounding AKSA 10 watter?)
Midrange The Focal Audiom 6W
and woofer the Focal 10W 6452 (out of prod. now, but cheaper and almost the same specs as the new replacement)

However the speakers are not formed yet.. I am busy of finding a good speaker maker for the enclosures. And I have also Black Hole 5  damping material in house.
SO I am using  the DEQX to play with my Home theater front speakers (400 EURO a pair appr. 480 US dollars) reasonable sounding but not for hifi stereo listening.
And guess what?
With the DEQX and AKSA and NAD 3020 (for the cheapy tweeter)  in active biamping they sound more high end, offer equal pleasure in listening as

my neighbours Martin Logans and Naim amplifier.

The difference between active and passive (run of the mill x-overs) filters is a big difference in transparency, detail and attack time. harshness disappears.. The DEQX has more pleasant surprises but outside this topic.

Even with moderate amps, unless you have a very  high endish filter with auricaps standard from the factory, active xovers will give a bigboost in above properties.

When my vision of triamping has been realised I send you a postcard  

[Jens]

Yes, Benny,

This is entirely practical, and as time goes on I intend to suggest ways of doing it which minimize pain of construction.  The AKSAs are made for this role, and in fact Ben Williams, aka Tinker, Aspen's digital designer, has done just this, with Seigfried Linkwitz's active crossover (arguably the most sophisticated analog crossovers ever devised for domestic hifi) and SL's Phoenix dipole speakers (which are sensational, a novel approach, very, very fast with astonishing micro-detail).

So,  ...

Well, Hugh,

As you already know, you have an open invitation to come to Copenhagen and visit Chateau Thorsen / AKSA Scandinavia - it's just a matter of a few (he, he, he) hours on a plane and you'll be here.

I think I know a few places where you can get good versions of your favourite latte.

Thanks, Peter, for the very positive mention of my system. I can only say that it has become a lot better since you listened to it last year. First and foremost, the GK-1R is a phenomenal preamp that made my old preamp sound almost dull and bleak (although it was in fact not). The GK-1R simply has so much drive and dynamics that I don't think I've ever heard anything like it. Secondly, I have managed to implement a Behringer Ultradrive Pro DCX2496 electronic crossover and equalizer into the bass section of my system, which has definitely improved dynamics in the bass. Lately, my new silver interconnects (which I call the Equilibrium Cable) have removed yet another veil from the music.

To all AKSAphiles: Anyone visiting Denmark will be most welcome to stop by and have a listen to what I think is a seriously good implementation of AKSA amps. I live just outside Copenhagen with easy access to a direct bus line to Copenhagen town centre.

Cheers,

Jens

[bhobba]

Just a general question out of curiosity.

If people went down the active path would it be worthwhile having a separate power supply for each amp or would its value be marginal at best?

As an example I am thinking of a two way crossing over at say 2.5 khz. Obviously an AKSA 25 would all that is required for the tweeter and maybe 55w for the woofer - although if you use an MTM the extra 6db increase in sensitivity may allow you to get away with 25w.  So if you use the 25w for both do people think it is worthwhile still having separate power supplies?  

One issue, if I read what high says correctly, is you get a better treble out of the AKSA is you use a less powerful transformer - the recommended transformer is a balance to get the best for all frequencies.  So I suppose the question is the gain worthwhile?  

Thanks
Bill

[andyr]

Just a general question out of curiosity.

If people went down the active path would it be worthwhile having a separate power supply for each amp or would its value be marginal at best?

As an example I am thinking of a two way crossing over at say 2.5 khz. Obviously an AKSA 25 would all that is required for the tweeter and maybe 55w for the woofer - although if you use an MTM the extra 6db increase in sensitivity may allow you to get away with 25w.  So if you use the 25w for both do people think it is  ...

Bill,

Easy answer.  You want the best ... that's why you are using an AKSA.  AKSAs sound best when they are constructed as "monoblocks" - even if you have (like I do) 3 "monoblocks" in the one case (25w/55w/100w).

A "monoblock" is simply one amplification channel with its own power cord and power supply - so I have 3 power cords going into my "3-channel AKSA".  Actually, each "box" is really two - one containing the amplifiers and the other the PSes - but that's another story!!

Regards,

Andy

[MikeC]

Andy

This thread couldn't have been timed better if I planned it. I have just been bending Hughs ear regarding the same thing you have done, although I wasn't planning on going to three power cords per channel . Please give more details. This will eventually drive a Linkwitz Orion.

Hugh, I might bite sooner than I indicated, as I could have a buyer for my Proceed amp. I can but hope.

Cheers

Mike

[andyr]

Andy,

This thread couldn't have been timed better if I planned it. ... Please give more details. This will eventually drive a Linkwitz Orion.

Mike

Hi, Mike,

Linkwitz Orions is what I would be doing if I didn't have my Maggies - you'll have a fantastic system.  However, you may need 4 amp modules per side - don't the Orions have 2 x 830500 Peerless for the base?  If so, I think you should use a 100N+ for each driver.

You can fit a 100w + a 25w on one heatsink and a 100w + 55w on the other - as long as these heatsinks form the edges of the box - so they are in the open air. (My own setup has the 100w on one h/s and the 55w + 25w together on the other and they only ever get slightly warm - even when playing Pink Floyd as loud as  I want to play it!)

However, this requires an extra large box - so I put all the PSes in one case and the amp modules in another - so I could use standard-sized cases.  25a automotive wire delivers the +/-/earth from PS box to amp box.

If you look on the "Pictures" are of the AKSA site, I'm pretty sure you'll find some pictures of my setup.

Good luck,

Andy

[MikeC]

Hi Andy

Thanks for the reply. Sorry I am only catching up now; I have been absolutely flattened by flu  

SL's recommendation is for 4 x 50W per channel, i.e. one 50W module per each bass driver. I would tend to agree with you if the bass unit was the 12" perless, but as it is the 10" 830452, I should be OK with one 100W sharing these per channel. The limitation in the bass is the drivers excursion limit, not VC power handling. I was tempted to modify the design by going straight to 12 " bass units, and I probably will one day, once I have the originals built as references. Unlike Hugh, SL is firmly of the opinion that you are on your own if you deviate in any way from his design.

I have never owned Maggies, but it is the memory of what they (and other dipoles I have heard) do well that persuaded me towards the Orions. One local dealer used to sell them with a completely new very rigid frame with extension wings for improved bass, as well as modified crossovers. They did sound very good on the right music, but I never had the money for them, and probably still don't. Very power hungry too, if I remember correctly? I'm sure yours sound wonderful with all AKSA amplification.

Cheers

Mike

[kyrill]

Bill,

Easy answer.  You want the best ... that's why you are using an AKSA.  AKSAs sound best when they are constructed as "monoblocks" - even if you have (like I do) 3 "monoblocks" in the one case (25w/55w/100w).

A "monoblock" is simply one amplification channel with its own power cord and power supply - so I have 3 power cords going into my "3-channel AKSA".  Actually, each "box" is really two - one containing the amplifiers and the other the PSes - but that's another story!!

Regards,

Andy

Hmm...
the primary windings of the different transformers do "see'each other. The separation happens on the secondary windings.

Therefore you do not need 3 powercords. You only multiply the "antenna" for RF pickup. If shielded you triple the cost of the powercords

Maybe I overlook something?

[andyr]

Hmm...
the primary windings of the different transformers do 'see' each other. The separation happens on the secondary windings.

Therefore you do not need 3 powercords. You only multiply the "antenna" for RF pickup. If shielded you triple the cost of the powercords

Maybe I overlook something?

Hi, Kyrill,

Maybe ... I don't know!  I am merely a journeyman DIYer, working by logic.  I have no theoretical background in electronics or electrical engineering.

You say "the primary windings of the different transformers do 'see' each other".  Well, perhaps they do ... it depends how you are saying the two transformers 'see' each other.

Are you saying because I have 3 toroids in a single case, they must have intertwined magnetic fields?  Thus they 'see' each other.  Or are you saying, because each toroid primary is connected to the AC mains, they automatically 'see' each other??

If so then the primary circuits of the power transformers of a pair of monoblock amplifiers also 'see' each other because they are both connected to the mains?  So why bother to have monoblocks?

The logic to my setup is as follows:

*  it is better to have separate power supplies to each channel of an AKSA - Hugh proved this to his satisfaction during his testing phase, which is why he sells the kit with a "stereo" power supply.

*  you could have both these power supplies share a common power transformer but Hugh has also proved it gives better sound to have separate power transformers for each channel.

*  the reason for this is that power demands in one channel do not compromise the power required by the other channel.

*  taking this to the next stage ... each power transformer should have its own power cable/switch/fuse so that current demands of one transformer do not starve the other.  One does this with a conventional pair of monoblocks (which together make up a stereo amplifier) ... so why shouldn't the same logic apply to a 3-module AKSA which feeds one channel?

And when was cost a consideration if you are going for the ultimate!!??

Regards,

Andy

[kyrill]

Separate transformers  do separate the channels thru their secondary windings. what is behind the secondary windings (the whole electronic circuitry) of another transformer is unknown to the circuitry as it  cannot  "see" behind its own transformer. So electronic 'networks" or amps do not "see"each other and are complete separated from each other.

The primary windings are all connected to each other thru the main line That is why we notice power fluctuations in the main line and why the power is so much cleaner in the middle of the night.

"* taking this to the next stage ... each power transformer should have its own power cable/switch/fuse so that current demands of one transformer do not starve the other. One does this with a conventional pair of monoblocks (which together make up a stereo amplifier) ... so why shouldn't the same logic apply to a 3-module AKSA which feeds one channel? "

This next stage is questionable in my eyes. Because the logic that is applicable to the secondary windings is not the same for the primary windings.
 The "starvation"will not be diminished or lessened by extra wire, fuses or switches. The starvation if it happens is the "blow out" of the 16A fuse of that particular circuit in the house (houses have more than one circuit  paralell to each other. Practically, the city's source of power will be "infinite" thru your house to the AKSA's and will never run out of steam.

[andyr]

Separate transformers  do separate the channels thru their secondary windings. what is behind the secondary windings (the whole electronic circuitry) of another transformer is unknown to the circuitry as it  cannot  "see" behind its own transformer. So electronic 'networks" or amps do not "see"each other and are complete separated from each other.

The primary windings are all connected to each other thru the main line That is why we notice power fluctuations in the main line and why the power is  ...

Aah, Kyrill, I think we disagree just here:

You said "The 'starvation' will not be diminished or lessened by extra wire, fuses or switches.  The starvation if it happens is the "blow out" of the 16A fuse of that particular circuit in the house (houses have more than one circuit parallel to each other.  Practically, the city's source of power will be "infinite" thru your house to the AKSA's and will never run out of steam."

I say if one power cord is being shared by two power supplies (ie. two power transformers) then, if high current is being drawn by one, this will tend to limit the current which is able to be drawn by the other power supply - due to the resistance of the power cord.

Having a separate power cord for each AKSA module/power supply does not make this issue disappear entirely ... but it transfers it back to the limitations of the house's electrical wiring.  And, no, this is definitely not infinite ... have you ever had the joy of hiring a sanding machine to sand smooth your floor boards?  I can assure you, the lights dim when you turn one of those mothers on!

Regards,

Andy

[kyrill]

Hi Andyr

Aah, Kyrill, I think we disagree just here:

You said "The 'starvation' will not be diminished or lessened by extra wire, fuses or switches.  The starvation if it happens is the "blow out" of the 16A fuse of that particular circuit in the house (houses have more than one circuit parallel to each other.  Practically, the city's source of power will be "infinite" thru your house to the AKSA's and will never run out of steam."

I say if one power cord is being shared by two power supplies (ie. two power tr ...

Having a separate power cord for each AKSA module/power supply does not make this issue disappear entirely ... but it transfers it back to the limitations of the house's electrical wiring. And, no, this is definitely not infinite ...

 have you ever had the joy of hiring a sanding machine to sand smooth your floor boards? I can assure you, the lights dim when you turn one of those mothers on!

Practically infinite power within the limits of the 16A, not theoretically infinite. But practically yes, in relation to the interaction between the AKSA's.

I say if one power cord is being shared by two power supplies (ie. two power transformers) then, if high current is being drawn by one, this will tend to limit the current which is able to be drawn by the other power supply - due to the resistance of the power cord.

Theoretically again yes, but practically?
Maybe Hugh or another more engineered person may shed some light on this?

The negative effects of RFI and other unwanted signals multiplied by more "antenna's"do play a role too.

[AKSA]

Hmmm, Kyrill, I'm not sure I want to go there!!  You and Andy have said it all!

In truth, any power source, AC, DC or swings both ways, will have a source resistance, or impedance.  A heavy current draw will certainly drop the line voltage, and yes, electric motors turning on will certainly dim the lights.

Line voltage sag is modified at the DC end of a power amplifier by the configuration of the transformer(s) and power capacitors, and of course the current demand of the amplifier, which is highly variable, literally in phase-shifted step with the music.  You can see I'm painting a picture of some complexity here.......

Just as the primary of a trafo 'sees' the secondary of the same trafo, then so this works in reverse;  this is not a mirror, but a window.  However, the source resistance of the mains is around an ohm, though complex of course, so the glimpse the secondary catches of the primary is fleeting as 1R is very low and it can't see too much.  If we use two trafos, one for each channel, then the view each has of the mains is identical, and the impedance so low that cross talk becomes almost indetectable. This does manifest as superior channel separation;  I've done tests with single versus dual supplies and the evidence is very clear.

Further, the size of the filter cap bank is also significant, since the higher it is, the less the amp 'sees' the primary;  it only sees the filter caps, and to an extent, the rectifier and the secondary.  There is also the matter of the source impedance of the bridge rectifier and the caps, which is complex and discontinuous and very strongly influenced by the quality of both.

To my thinking and in my experience there is not much to be gained on the primary side.  The benefits are gained with the choice of rectifiers and filter caps, and maybe to a minor extent the power trafo.  I have witnessed A/B blind tests across a sample of 6 audiophiles with very different transformers and the differences are almost indetectable between double C cores v. toroids of the same capacity.  In fact, no one person could reliably pick the difference.  This leads me to believe that the primary determinants in the 'sound' of the power supply come neither from the transformer nor the mains nor the power cabling, but rather the rectifiers and filter caps.

Of course, this is just one man's opinion, YMMV, I could well be wrong, and lots of people are cleverer than I am, etc etc....  This is partially, anecdotally substantiated OPINION, and if I stand under a pyramid surrounded by citrate crystals with rhinestones and razors on the floor I could well think differently.  I am aware that there are whole religions (and marketing strategies!) founded on these interested precepts, and I won't fight, disagree, or otherwise cause angst to anyone.  We are talking here about what people HEAR, and this is psycho-acoustically subjective, and this should be stressed again and again.  

This may not help, Kyrill, but we all live in hope........

Cheers,

Hugh

[andyr]

Actually, Hugh, I should tell you about my new GK-1 tweak - it really works, I swear!!

I bought some 5x9s silver bar and made up two little pyramids which go around the tubes (which are sticking out through the top plate).

What an improvement!    

Next tweak is to make a bigger version that will fit over my head, while I'm sitting listening.  

Regards,

Andy