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First One - mosFET amplifier module

It is not a question of "speed". It is a question of stability margin.
And, if the measurements of Lazy cat in the first posts of this thread are right, FO is rock stable. Even loaded with 1µF // with 6 Ohms.
So what ? It seems, indeed, there is a problem, as many amps seems to had burned away in several and various builds. Why ?
If i was L.C., i would try to figure-it out seriously.

Among 600+ modules out there, only fistful of them reported here to be troublesome. Few calibration mistakes (slipped probes), few wrong PSU polarity connections and few SMD/THT part failures reported. Modules are stable, having 9 compensation locations to enable sufficient phase margin and to stop parasitics to enter the loop. Having new FO M in preparation I can only suggest replacement of the broken modules with new ones, since that would be cost effective and much cheaper than separate repairs.
 
20180325_185845.jpg

Removed coil for repair with new 39 0hm resistors.
 
Among 600+ modules out there, only fistful of them reported here to be troublesome.
Ok, an effect of Internet, so.... Few people (in percent) report suddenly a problem and it looks like the all batch is affected because the satisfied owners keep silent.

Anyway, I remember to had spend a lot of time in the SAV offices of the company I was working for, after the first samples of a new amp were returned with failures, to figure-out the the weaknesses of our designs.
 
Just those four Duelund caps probably cost more than the amp modules, smps and chassis...
10µF 100V: more than 500€.
Each, not an order of 100. Made of 100% pure snake oil.
It would make me laugh if so many people don't have so much trouble living.
Not a good idea if the purpose was to promote an amplifier board of very good value for money.
 
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10µF 100V: more than 500€.
Each, not an order of 100. Made of 100% pure snake oil.
It would make me laugh if so many people don't have so much trouble living.
Not a good idea if the purpose was to promote an amplifier board of very good value for money.

We play with whatever comes in reach of our hands, no limitations, no hesitations, no regrets.
 
10µF 100V: more than 500€.
Each, not an order of 100. Made of 100% pure snake oil.
It would make me laugh if so many people don't have so much trouble living.
Not a good idea if the purpose was to promote an amplifier board of very good value for money.

Unfortunately they are not snake oil. In a system resolved enough to hear
differences in caps they are indeed probably the best.

I have a friend who owns commercial speaker company and his top line models use Duelunds in Xovers. Commercially it doesn't make sense to use
them but as he said, once you use them there's no turning back.... and he would prefer not to.

Personally I won't use them - stupid money.
 
I heard that you made some changes in new model and i see you used melfs. And amps suits very good with new Ubiq speakers. Excellent. Se us at Munchen.

Like to play with SMD suckers, love their tough guy's attitude especially when 0805 flying across the lab, now find me.

Compared to Duelund this 0805 Vishay resistor in the same metric volume would cost 100 k€. Few of them found the place on FO XL.

http://si.farnell.com/webapp/wcs/st...estType=Base&partNumber=2765170&storeId=10175
 

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Unfortunately they are not snake oil. In a system resolved enough to hear differences in caps they are indeed probably the best. .
Because they are the most expensive ?
It is (omho) like an aspirin that some sells for 100 time the price pretending it cures Cancer !
Nothing can justify their price. Nothing.
And you will notice that there is 0 measurements on their site. (of course)
But as they look amazing and are outrageously outpriced: they surely sound "amazing".
 
Because they are the most expensive ?
It is (omho) like an aspirin that some sells for 100 time the price pretending it cures Cancer !
Nothing can justify their price. Nothing.
And you will notice that there is 0 measurements on their site. (of course)
But as they look amazing and are outrageously outpriced: they surely sound "amazing".

Ok we get it. You are frustrated with Duelund pricing and all. And I agree. They are outrageously overpriced.
But lets not hijack this thread and turn it into snake-oil debate. Duelunds are not the piece of standard board anyways ;)