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Old 6th December 2005, 05:29 PM   #11
Nordic is offline Nordic  South Africa
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Well, if the alternative is just making the same mistakes and not moving on, then I think this is a step in the right direction...

In Mauro's defence he has always stated that some of the design principles were compromises, ones he was ok with, and also to some extent I'm sure some of these compromises included not haveing to spend as much on components.

There may yet be more elegant soutions as you alude to, but in the mean time us hobby types who didn't have the priviledge to have an electronics education, are haveing fun, learning good fundementals (sometimes the hard way), and most importantly building some decent amps.

Quote:
Yes, you have better results by snubberizing those big caps.
Yes, you have better results with discrete diodes, and the MUR860s are very good. This was reported years ago by Peter Daniel.
What are you guys doing, sleeping?
Well these weren't in the Mauro amp, and now they are... I would hardly call that sleeping!

Have a good evening.
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Old 6th December 2005, 05:49 PM   #12
t. is offline t.  United Kingdom
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Hey Carlos, great to see you on here
Thanks to Rudi for the new board layout and for opening a tweakers thread for this amp

After all the hype etc for this amp and seeing as though I built both Carlos and Pedja's chipamps why not try this one too, I already have the biggest part of the bits knocking around so I decided to etch the boards and give it a try

I first stook to the RevC parts list etc but used Rudi's layout because of the dual rectifiers which I thought would be better in the long run.
The amp is actually not bad but I was not happy with the bass to be honest
I've always felt Carlos amp had by far the deepest tightest bass out of any of the chip based amps and Pedja's had the best top and sheer clarity, this is MY opinion and in MY system

I now have swapped the standard diodes to MBR10100 Schottkies, removed all the small 100nf decoupling caps off the top board and cut the legs much shorter and soldered them directly to the LM318/LM3886 pins undeneath, the zener for the LM318 has been removed and replaced with seperate diy boards with LM317/337 TL431 set to output +/- 15v, added 2x 470uf back to back low ESR caps in the fb
I prefer the amp already to the original, I will also of course try the snubber too next

Thanks again to Mauro for sharing another amp to play with and to Rudi for the layout and fb tweak and to Carlos,Pedja etc for all the advice and nice diy amps to build in the past

This will probably be my last chipamp project after a few more mods to this one, I'm going to try the Hpex classD modules next
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Old 6th December 2005, 06:25 PM   #13
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Quote:
Originally posted by Nordic
Well these weren't in the Mauro amp, and now they are... I would hardly call that sleeping!
I hope you haven't taken my post personally, it was not meant to.
But it was funny to see everyone defend this as an untouchable design, and the best chipamp ever (!!!), and defending the (finally admitted) compromises as good, including those that have only one experience with the LM3886 chip: this amp.

I repeat, I respect Mauro (despite his attitude against me since the beginning, I don't know why) and I think this amp was initially created as a pure exercise, he didn't expect it would go on to a commercial offer and so many people building it.
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Old 6th December 2005, 06:28 PM   #14
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Rudi, what does 'GECO AUDIO' means?

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Old 6th December 2005, 06:35 PM   #15
Nordic is offline Nordic  South Africa
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Hey T, couldn't help but notice about the scotkies, (forgive spelling) When I spoke to Rudi yesterday, he mentioned specificaly that he used them, but that they sounded horrible to him, if memory serves correctly, he did like the MUR860 or 680s...

Have you tried those?

Quite frankly the amp is not that bad, in that we are mainly just changeing the power supply circuitry, with the amp basicaly still in basic config.
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Old 6th December 2005, 06:37 PM   #16
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Default boards or kits.

I have had several request for boards or kits.

first of all i will not be able to do any during the december timeframe. sorry guys. it is summer in south africa and evertyhing is closing down during Dec.

I will have to do a investigation to the shipping cost to several countries. the south african postal system is a ripoff and i need to secure delivery if I were to do kits.

the goodnews is that i do have 400 sprague caps available that do add to the performance of the amp

please mail me if you are interrested and i will file all request and act on it during Jan 2006 (which is not that far away)
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Old 6th December 2005, 06:41 PM   #17
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Quote:
Originally posted by Nordic
When I spoke to Rudi yesterday, he mentioned specificaly that he used them, but that they sounded horrible to him, if memory serves correctly, he did like the MUR860 or 680s...
actually i said that the MBR 10100 gave a very good sound and were very clean but the MUR 860 gives you the bass. most speakers would need this . T. has transmission line speaker and he can sacrifice the bass a bit in order to get more clarity, and the MBR10100 did give me that, it is very nice but robbed the bass a bit
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Old 6th December 2005, 06:42 PM   #18
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Quote:
Originally posted by Nordic
Quite frankly the amp is not that bad, in that we are mainly just changeing the power supply circuitry, with the amp basicaly still in basic config.
Still, the PSU can make a HUGE difference on the sound of the amp.
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Old 6th December 2005, 06:43 PM   #19
t. is offline t.  United Kingdom
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Quote:
Originally posted by Nordic
Hey T, couldn't help but notice about the scotkies, (forgive spelling) When I spoke to Rudi yesterday, he mentioned specificaly that he used them, but that they sounded horrible to him, if memory serves correctly, he did like the MUR860 or 680s...

Have you tried those?
Hi Nordic,

I've tried several including the MUR860 and MSR860, remember this was in my system and my opinion, I personally find the MUR860 to have too much of a sonic signature compared to the schottkies, some people report the schottkies to have no bass and be a bit lifeless but I find them to make the sound less coloured, the Mur860's do seem to add more bass and mids, its down to you if you want this or not
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Old 6th December 2005, 06:47 PM   #20
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Quote:
Originally posted by t.
I've tried several including the MUR860 and MSR860, remember this was in my system and my opinion, I personally find the MUR860 to have too much of a sonic signature compared to the schottkies, some people report the schottkies to have no bass and be a bit lifeless but I find them to make the sound less coloured, the Mur860's do seem to add more bass and mids, its down to you if you want this or not
And what is your reference when you compare those two types of diodes (by saying one adds, the other does not)?
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