Simple Killer Amp - Listening impressions

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#282
So are there any other constructors of the SKA out there who've listened to the amp and care to offer perspectives to provide a more rounded picture.

The folks who've posted opinions so far have all said that the amp is very good to excellent and we need somebody to say its rubbish to balance things 😀 Perhaps then some of the unfounded negative posts will become less frequent 😉
 
#283
hifryer said:
Two points Eva.

2. When you build your crossovers, can you hear differences that don't show in any of your measurements?? Gottcha!!!!! ;-)

cheers,
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I hear random differences as reliable as a coin flip. Sometimes I have to practise ZEN 😀 in order to clear my mind and avoid falling in nasty self-suggestion and positive-feedback effects based on things like mood, weather, appetite or "listening impressions" threads 😀

p.s.: It always sounds right if I have to hurry up to finish it, particularly when I'm hungry.
 
#284
Terry Demol said:
No forum ********, no slanging matches, just let the product stand
on it's OWN feet.
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For my point of view its doing just that.

It doesn't need comparisons for me, nor measurements and certainly not an analysis into its inner workings.

Its just a fine amp that has brought me to that threshold where I don't care anymore, I don't feel the need to immediately try something else. Contentment is the best word to describe the whole thing. And I can't say I've completely had that before with my other amps (both commercial and DIY), the AKSA was very close but I just think my tastes got in the way of what it was doing, the SKA pampers to those same tastes very well.

I'm a bit of a serial swapper and rarely sit on anything for more than a few months. If I come back later this year and I've still got the SKA's - then that should speak volumes.

In terms of audio there are a few things that I can say I truely lifetime keepers for me:

ATC's SM75.150S midrange driver
Digital room compensation (in its ever evolving state)
Bit perfect playback

The rest is up for constant swapping and I very much doubt I feel as strongly about the SKA as those but I think I'll be keeping it for more than a few months.
 
#285
Eva said:
Sometimes I have to practise ZEN 😀 in order to clear my mind and avoid falling in nasty self-suggestion and positive-feedback effects based on things like mood, weather, appetite or "listening impressions" threads 😀
Click to expand...

So why not go to a thread? There's plenty to choose from.
I don't understand, do you have some pleasure with pain?

It's a shame that posts are disappearing (not even to Texas we go), you've just missed the fun. 😀
 
#288
Eva said:
I was expecting something more elaborate, so I got quite disappointed when I saw the schematic:

An externally hosted image should be here but it was not working when we last tested it.


It speaks for itself.

Just consider that the gates in this circuit are current-driven directly from the LTP and that MOSFET input and reverse transfer capacitances change by an order of magnitude depending on Vds across the amplifier output voltage swing. Also consider that, in any MOSFET, Id is proportional to Vgs^2, thus requiring the highest and most non-linear gate drive AC currents at the lowest Id levels (during low level recording details) and vice-versa. Now imagine what happens when reactive loads are driven and zero-current transitions don't happen with the same Vds, gate capacitance or gate threshold where bias was adjusted... The battered input LTP is left with the chore of compensating for all this mess.
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Eva,

Sorry to say this, but I find your analysis a bit misleading.

There are 2 critical points in the major success of this design.

1) The OP MOSFET is driven by a high beta high Ft BJT follower.
The followers job is to address the highly non linear capacitive load
of the MOS. Looking into the IP of the follower you will see virtually
NONE of this highly reactive load and it will handle the load easily
provided the right device (bjt) is chosen.

2) The follower needs to have a high IP impedance, and the IP LTP
needs to have a high OP impedance to get good open loop gain.

This is directly at odds with DC stability and is where the bootsrap is
intrinsic to the design. It provides ultra high AC loop gain but with
good DC stability.

The long tail pair, if run with the right current and degeneration
will drive this CCT well and with good linearity.

Now if I have got this wrong, I will expect an email from Greg and
I will be happy to correct myself here.

Having said all the above, as with 98% of globally closed loop
designs, it doesn't measure as well at higher frequencies and
power due to lower loop gain. But for such a simple design
it achieves a lot with little.


Cheers,

Terry
 
#290
hello all,greetings
a couple of point

all jop doing by ltp, no compensation shown, very good
i havent test such circuit, ef i see no problem

ltp i am not sure what's ol transconductance
b00strap not very good psrr, decouple ltp for >psrr

Greg Ball very good designer!

leben und arbeiten sie in den Telefunken-HIGHEND

Klaus
 
#292
Well guys, i think we are not going very well.

As one of our best moderators, the always fair one entered.

So, our behavior is not going very good.

Well, in my point of view, when some figth started, that will produce problems to designers and doubts inside the common mortal heads, related wich one to construct or buy.....it seems to me that the thread is near to be comdemned.

I will silent....as i already made some foolishes .

Weldon do not enter just to show himself.....in the opposite, he do not enter normally...but when he enter....no doubts that something is wrong.

regards,

Carlos
 
#294
Hi All

Here's a photo of my GB300D
rgds
 

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#298
Those modules look enormous compared to the GB150's

Nice work KLe. I've ordered a pair from Greg but it looks like another couple of weeks before I'll have them since he ran out of PCB's.

Will be interested in your thoughts. You have the GB150's also don't you?
 
#299
ShinOBIWAN said:
Those modules look enormous compared to the GB150's
Nice work KLe. I've ordered a pair from Greg but it looks like another couple of weeks before I'll have them since he ran out of PCB's.
Will be interested in your thoughts. You have the GB150's also don't you?
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Hi ShinOBIWAN
Thankyou and no, I only have the GB300D's. As they keep running in, they sound better and better, but, I will report once they are more run in. 🙂

Did you notice a run in period for the GB150D's :Pumpkin:
 
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