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Old 16th July 2005, 03:47 AM   #11
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Quote:
Originally posted by kanaddict


I was about to order a kit from autoconstruire.com, but now that there is another kit available (soon).....I have some trouble to choose.....AMP6 or autoconstruire.com kit

A few weeks ago, all I was able to find was kit using SMD components and now there is two kits ! Because of the low price of 41Hz kits, I'll be tempted to buy the AMP6, but someone said that the AMP3 (similar to the amp6) is good but not as good as the best GC. I'll buy the tripath amp hopping that it will sound better then BrianGT NIGC I built last winter. The GC sound very good for the price, but I had a T-AMP for a few weeks and I know that it was better (If we forget about the bass problem). So, I suppose that I'll have to wait for more input about the sound of these design.

Regards,
I and several others have reported the superiority of the Amp3 over the extensively modified SI. You like the stock SI over the gain clone so what does that say to you about the credibility of the person who stated the GC was better than the Amp3? There was possibly something wrong or they even listened to them in different setups. One never knows about out of context statements like that. My personal setups were absolutely identical for the comparison, gains matched and all. I also used near field listening with high quality single driver monitors, hard to miss differences with this setup.
The only possible wrench in the works was if the speakers used presented a complex load and/or were very inefficient. Would hardly be a fair comparison if one amp is clipping and the other was not. There is some science to doing proper listening tests.
Roger
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Old 16th July 2005, 08:56 AM   #12
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I have built a few amps, one of them is a GC which I spent a lot of time on, it has J-fet buffer, zerofeedback regulators, Caddock and Riken resistors, BG caps etc.
I built the Amp3 and run it off a 12v 7aH battery with 20k caps.
The sound was good but not as good as the J-fet buffered GC.
I have since built Carlos snubbered regulator using BG caps,MBR10100 schottky diodes, added polypropylene coupling caps and a stepped Attenuator,a pair of 680uf BG NX decoupling the supply rail on the pcb the sound of the Amp3 is now excellent
The next thing I'll be trying is NUUKS SMPS for the Amp3.
I've been told various times that the PSU is the key thing to get right with the Tripath chips
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Old 16th July 2005, 05:36 PM   #13
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Default Results! Yes!

Thank you, There had been some questions hanging and you have answered most of them. I am surprised the GC is that good I really had no idea. Of course you did a lot of tweaking. Even with the Amp3 having the disadvantages of SLA power and stock coupling caps this is surprising. Did the Amp3 have many hours on it when you made this observation? Could the available power have had much influence? Running the Amp3 to 14.5 volts will defiantly help power out. What voltage are you supplying to it?
I will be looking forward to your report on the differences with the SMPS. An experiment to try, using a single large buffer cap or multiple smaller caps. The multi cap solution should be better as long as total capacitance is close. It will have considerably lower ESR. I would think a total of at least 10,000 uf should be used and more should be better up to maybe 30,000 total. Beyond that the benefits are questionable and charging them up on turn on can be a problem. Maybe 5 of the super low ESR 2,200uf @ 16v computer caps would work best, worth a try. I have been replacing the small output caps on my SMPS with larger Sanyo low ESR computer types and they work very well there.
Which Stepped attenuator are you using? I like the DACT 10k and have been using them. Kind of ironic, using a VC part that is more expensive than the amp. But I think the sonic quality of this little wonder requires the best support parts around it.
Roger
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Old 16th July 2005, 05:54 PM   #14
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Good timing Roger
I've had the SMPS on all day, this is the best i've tried yet, the output is just over 12v and it beats my diy regulator IMHO which was tried at 14.6v and 12v, to me a battery with 10/20k caps sounded the worse.
I now use NUUKS SMPS,10,000uf Siemans sikoral and Carlos latest snubber
The 22k Attenuator I use is one of those types using the vishay dale resistors, it was cheap off e-bay, btw its very important to run something like a signal generator through all the resistors first, it makes a big difference burning in those dales although a bit of a pain wiring all the resistor ends to a plug. they sound flat when new

The GC sounds very good when used with a nice discrete buffer and zero feedback regulated supply, its not really fare to say the Amp3 now beats it, I just prefer the sound of the Amp3

Not bothering with output wattage I'd be very interested to know how something like the UCD180 would compare regarding sound quality

Forgot to mention that the Amp3 had a good few hours running time when it was compared to start with.
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Old 16th July 2005, 06:34 PM   #15
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Default UcD modules

Leo,
The UcD 400 with the upgraded opamp is just a little more expensive than the same type 180 module. It will run very well with lower voltage but always leaves the option open to dramatically increase power by upping the rail voltages.
I have not done an A/B of these 2 modules and am only using the 400's but reports favor the 400 as being the better sounding part. It is a newer design and improvements were made. These modules are sensitive to the same things the smaller Amp3 and SI are, coupling caps, power supply caps and the power supply itís self.
Now you are talking some very serious Hi Fidelity!
Roger
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Old 16th July 2005, 06:46 PM   #16
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Cheers Roger, they sound tempting
I've actually got a nice PSU running my Avondale NCC200 which should be suitable for one of these units
I'll have a look on the site regarding the UCD400
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Old 16th July 2005, 09:20 PM   #17
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Default UcD power requirements

Leo,
The UcD modules have very good PSRR due to their closed loop design and work quite well with simple unregulated supplies. Of course like any other audio product they will do better with a better supply. I would say ďgive them a tryĒ Not that much money if you donít have to lay out extra cash for a PS and chassis.
They immediately became my new reference for amps, even including my own highly tweaked designs! The only change that I consider mandatory is an upgrade of the input coupling caps. Same as the Amp3 2-4 uf works well.
Roger
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Old 17th July 2005, 12:17 AM   #18
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Quote:
Originally posted by sx881663

I and several others have reported the superiority of the Amp3 over the extensively modified SI. You like the stock SI over the gain clone so what does that say to you about the credibility of the person who stated the GC was better than the Amp3? There was possibly something wrong or they even listened to them in different setups. One never knows about out of context statements like that. My personal setups were absolutely identical for the comparison, gains matched and all. I also used near field listening with high quality single driver monitors, hard to miss differences with this setup.
The only possible wrench in the works was if the speakers used presented a complex load and/or were very inefficient. Would hardly be a fair comparison if one amp is clipping and the other was not. There is some science to doing proper listening tests.
Roger
Hi Roger,

All you said make sense. I now know that the AMP3 sound better then my GC (amp3 better then SI + SI better then GC ==> amp3 better then GC)

This don't change my interrogations ...
1- I wonder if the AMP6 will sound as good as the amp3
and
2- If it's the case, I wonder if the AMP6 will be better then the autoconstruire kit

I'll have to wait and see if someone post about a comparative listening.

What you said abut the Ucd400 is very interesting. I'm new to class D amp and know nothing about the Ucd amp. From what you said, I would think that the Ucd400 sound better then the amp3. Could you please tell me what the Ucd400 do better then the amp3 ? I'll start to read about the Ucd400, but since you have both amp, your in good position to give me s serious opinion.

By the way, I do nearfield listening



Thanks !
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Old 17th July 2005, 12:53 AM   #19
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Default opinion

Daniel,
The only guarantee I can give about my opinion is that it, indeed, will be serious. The UcD technology is a closed loop design that includes the output filter. As most really good designs seem to do it tests very well in addition to sounding excellent. It has far less load dependency problems and donít seem to mind complex crossovers or impedance nastiness. After some simple upgrades the sound is state of the art. It has all the magic of the Amp3 only more so. It has far more authority, neutrality and just plain hear through quality. Being an all discreet design also means less grain and grunge so is more in focus with a deeper sound stage. I love it and whole heartedly recommend it!
Bruno has done a truly exceptional piece of work here, bringing musical enjoyment back into Hi Fi.
Roger
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Old 17th July 2005, 12:59 AM   #20
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Quote:
Originally posted by t.
I have built a few amps, one of them is a GC which I spent a lot of time on, it has J-fet buffer, zerofeedback regulators, Caddock and Riken resistors, BG caps etc.
I built the Amp3 and run it off a 12v 7aH battery with 20k caps.
The sound was good but not as good as the J-fet buffered GC.
I have since built Carlos snubbered regulator using BG caps,MBR10100 schottky diodes, added polypropylene coupling caps and a stepped Attenuator,a pair of 680uf BG NX decoupling the supply rail on the pcb the sound of the Amp3 is now excellent
The next thing I'll be trying is NUUKS SMPS for the Amp3.
I've been told various times that the PSU is the key thing to get right with the Tripath chips
Your path to Amp3 nirvana has been almost parallel to mine, but much more thorough .

I spent months tuning my buffered TDA7294 chipamp to the point that it's been favourably compared to the venerable Sugden A21a and some other nice amps. Snubberized power, couple of BG Hi-Q NX, etc.

With much less fuss, my Amp3 (very similar treatment to yours) has displaced the chipamp almost permanently. One thing though: there's a battery powered buffer after my 41-step TKD attenuator. The buffered volume control makes a larger difference than the move from 7Ah SLA + good reservoir to linear supply. You're spot on regarding getting the PSU right, though.
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