Lower Rails

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petert1973

  • Jr. Member
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Lower Rails
« on: 19 Feb 2008, 12:12 pm »
Hi, this is my first topic.

I tried to construct a 55w aksa schematic in order to see how its sound.

I have a good toroidal 500VA (that i want to use ofcourse) with double rails at 2x22/each. This it will give me about 30-31 volt.
What do i need to change at bias or do nothing and keep it at 100mA/rail

Sorry for my poor english and thanks in advance for your answers

AKSA

Re: Lower Rails
« Reply #1 on: 19 Feb 2008, 08:37 pm »
Dear Sir,

Thank you for visiting our forum.

If you are trying to reconstruct the AKSA from information you've found on the web, it will be quite difficult, particularly as I must assume you don't have the pcb which is an important part of the design.

The amp can be set up for lower rail voltages by reducing the resistor which supplies current to the LTP.  The stage current to the LTP should be set at exactly one milliamp.

The other alternative would be to buy the kit and get help directly from the designer!

Cheers,

Hugh

petert1973

  • Jr. Member
  • Posts: 4
Re: Lower Rails
« Reply #2 on: 19 Feb 2008, 09:56 pm »
I respect the job you trying to do protecting your work. I realy do.

I just trying to get some idea of your schematic that you already published. I know also the secret parts.

If the results are so good i will buy the kits.

P.S Is there's a version with no heatsinks etc. Just the pcb's and instructions?

Thanks again

AKSA

Re: Lower Rails
« Reply #3 on: 19 Feb 2008, 10:51 pm »
My Friend,

The schematic will give you no idea how the amp will sound.  You cannot tell looking at the circuit diagram!!

In fact, I withdrew that schematic long ago - it was never my idea to publish it!

Unfortunately there is no pcb available on its own, only the kit.
 
Cheers,

Hugh

andyr

Re: Lower Rails
« Reply #4 on: 20 Feb 2008, 09:26 am »
Hi, this is my first topic.

I tried to construct a 55w aksa schematic in order to see how its sound.

I have a good toroidal 500VA (that i want to use of course) with double rails at 2x22/each. This it will give me about 30-31 volt.
What do i need to change at bias or do nothing and keep it at 100mA/rail

Sorry for my poor english and thanks in advance for your answers

Hi Peter,

Your English is fine ... however, your sense of logic seems to be a bit lacking!  :lol:  If you want to construct an amp as cheaply as you can (for soldering practice) and don't really care how it sounds ... there are plenty of second-rate kits around on the Internet.  :D

However, if you want to construct an amp which actually sounds great! - which all of us on this Forum did - then buy an AKSA (whichever variant you can afford ... and the more expensive kit you buy, the better it will sound!  :D ).

Unfortunately, your 500VA transformer is useless for an AKSA (any variant).  Part of the magic of an AKSA amp is that it has dual-mono power supplies ... so you need 2 power transformers, not one big one.

Regards,

Andy

petert1973

  • Jr. Member
  • Posts: 4
Re: Lower Rails
« Reply #5 on: 20 Feb 2008, 12:47 pm »
Hi again.

Answering to Hugh. There's a misunderstanding. Ofcource i dodn't expect to "hear" the schematic (this only happend to music reading a partiture "i'm a musisian") I have already built the amplifier and with no crosscheck if anything is wrong, works fine.
My honor to talking to you. :notworthy:

I'm not a newbe in diy. My other amp is Zen (and sounds fantastic)

Answering to andyr. I'm very experienced to soldering my friend. I tried to built Hugh's schematic because a lot of people says that its sounds good.
I have plenty of parts in my office and thought that will be a good idea to hear what that think sounds before buy anything.
The philosophy of using 2 toroidial per side its not fit only at Hugh's kit. Its a better solution for any amp (inlcuding AKSA).
This toroidal was the tranformer of my gainclone that i was disapointed very much (too much high frequensy)

Finally i dont beileve that a few better parts such as 8 black gate or starget and few dale resistors worth the money that Hugh ask for it (Sorry Hugh, my opinion) Here in Greece is very easy to find anything you like in order to upgrade your diy staf in affordable prices

Thanks for flattering about my english  :)


PSP

Re: Lower Rails
« Reply #6 on: 20 Feb 2008, 06:03 pm »
Quote
I have plenty of parts in my office and thought that will be a good idea to hear what that think sounds before buy anything.
and...
Quote
I have already built the amplifier and with no crosscheck if anything is wrong, works fine.

So... did this amp you built sound good enough to induce you to buy the real thing?  BTW, the Nirvana and Nirvana + upgrades involve changes in both part values and topology.  It's more than just a few Black Gates.

I don't work for free, and I don't think you want to work for free either.  Hugh's amps sound better than a number of very high-end competitors and IMO he very much deserves to get paid for his knowledge and for his fine design. 

Peter



Freddy57

  • Jr. Member
  • Posts: 6
Re: Lower Rails
« Reply #7 on: 20 Feb 2008, 06:38 pm »
    There, there, gentlemen.  It appears that our friend Peter here has wandered into the wrong Pub.  Though it also appears he didn't see the sign on the way in "Free Beer Tomarrow".  I'm sure he has been duly notified by the management. VERN

AKSA

Re: Lower Rails
« Reply #8 on: 20 Feb 2008, 10:34 pm »
Dear Petert,

It seems no good deed goes unpunished....  I regret posting that schematic, the more so since the very careful parts selection is not evident from it and thus the best available sound will not result.

It seems you have made your decision about the cost of the kit, and the upgrades!!  If you consider only the component value, you are right, but the knowledge of what to use and where to place it is worth something, surely?  You do not challenge the dentist to drop his prices because the anaesthetic costs $2 and the amalgam $5?

In any event, you need only ensure that the LTP stage current is one milliamp, nothing more, when you drop the rail voltage, although you can pick up some benefits by slightly reducing the lag compensation capacitor.

If you would like more information email me privately,

Cheers,

Hugh


kyrill

Re: Lower Rails
« Reply #9 on: 20 Feb 2008, 10:47 pm »
a good DIY knows enough that small changes in topology can have big sound effects
since that conceptual schematic of yester year small and not so subtle changes has been made

i do not belief that very first design will give you a good enough idea how an up to date Aksa will sound.

I am still surprised how upgrading my power line makes the AKSA sound so much better
i give it besides a balanced transformer the Felix as described in http://www.audiocircle.com/index.php?topic=50284.0
although the choke can have a max of 3A, i have 3A in 240 V which gives over 600 watts, enough for the Aksa 50

petert1973

  • Jr. Member
  • Posts: 4
Re: Lower Rails
« Reply #10 on: 20 Feb 2008, 11:49 pm »
Gentleman Please, im not a silly boy that the only thing that i want to do is to built something for free.

Ofcource i know that behind the 260€ that Hugh ask for his kit is the design. It isn't so much money if you consider that he gave you also heatsinks, pcb, parts, filter caps etc.

I didn't hear it yet, "works fine" means that the measures so far looks fine.

Hugh, i dont believe that was wrong to publish the schematic. Its very easy for someone who knows, to copy the whole board by a single picture.
How many is that persons that you afraid not to buy your kits.
We know KRELL schematics,MARANTZ, AUDIO RESEARCH, I use to work on Classe dealer and i have access to all schematics. So what???
How many is able to solder 2 transistor sibe by side, few
Nelson Pass doing this for years, i dont think that he lost money

Hugh, thank you for your help. This is the right way to find happy customers and not by chase at them (if I write it well)

gaetan8888

Re: Lower Rails
« Reply #11 on: 21 Feb 2008, 12:29 am »
...
Hugh, i dont believe that was wrong to publish the schematic. Its very easy for someone who knows, to copy the whole board by a single picture.
How many is that persons that you afraid not to buy your kits.
We know KRELL schematics,MARANTZ, AUDIO RESEARCH, I use to work on Classe dealer and i have access to all schematics. So what???
How many is able to solder 2 transistor sibe by side, few
Nelson Pass doing this for years, i dont think that he lost money
...

Hello

All those big companies can afford to do it, the few sales they would lose won't bother them, and most of them made those schematic accessible by the service manual for repair purpose only and not so we can copy them, Nelson Pass allway's wait after some times before making a schematic public for diy community and he can afford to do that, but few month ago one of his Pass Lab schematics did end up in a illegal commercial copy amp sold on Ebay and Nelson did need to put his attorney on the case, so there is risk to made amps schematic public.

But it's not all amp maker who made their schematics public, look at Mr. Antony Aulton, Greg Ball, etc, most of kit amps makers don't made their schematics public.

Hugh are the Aksa amps, he don't have big R&D and marketing budget like those big commercial amp companies, and he live with the sale of his amps, his design are very very unique and innovative. Lot of commercial amps names do their sale by agressive sales marketing, lot of gadget and a shiny big metal case but their amps topology are quite similar for most of them. Hugh do his sales by the sonic quality of his products, the excellent backup and help he give and the highly goods words from his customer and friends.

Bye

Gaetan

« Last Edit: 21 Feb 2008, 03:45 am by gaetan8888 »

VYnuhl.Addict

Re: Lower Rails
« Reply #12 on: 22 Feb 2008, 02:24 am »
Hi Petert,


    Once as you have just done, by factoring in all of the details and parts that make up the kit it comes out to one heck of a bargain in reality. Just consider the price of Aluminum these days, and the heat sinks supplied are high quality and EXPENSIVE to obtain, especially on a one off basis. Design is one thing and any manufacturer would be crazy not to factor in the pain and time that goes into parts selection, voicing and parts sourcing, no easy feat and consumes much time. Also in many designs, the layout is absolutely critical to the final result, and Hugh puts unimaginable hours and effort into honing this aspect of his designs and it shows in the quality of the products sonics. Layout is something that I have gained a phenominal amount of respect for, so easy to mess up and get wrong as I have managed to do in the past.  If Nelson Pass wishes to give out his designs its his choice, and he has chosen to let "some" float around, but it shouldnt be a precedent for any of us to assume that its our right to obtain this knowledge as if we do its a priviledge.



Sincerely
Colin