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Old 11th September 2012, 10:25 PM   #1071
sonnya is offline sonnya  Denmark
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Quote:
Originally Posted by Joachim Gerhard View Post
A cap multiplier was madatory on my build. Otherwise there was a small hum. I think that behavior is typical for class A amps with low open loop gain. See the JLH 10W.
That was what i was thinking.... I have a very small amount With my Ear less than 5 cm from the cone but it is a sub 90db speaker
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Old 11th September 2012, 10:34 PM   #1072
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My TSSA is dead quiet. Even on my plus 95dB speakers, It is so scary that i check if the amp is off when i leave the room.
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Old 11th September 2012, 10:34 PM   #1073
Salas is offline Salas  Greece
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Originally Posted by sonnya View Post
Sounds like horn system!?

Boom rocking ? Negatively???
No, its direct radiator stiff surround 6X9 ovals in parallel, and a 6.5inch PHL in another box above them. Positively I meant. That SSA had no problem grabbing at 26dB. Just checked the OLG its 45dB, a 2 stage amp too and the output is a follower. So its A=178, comparable to stock 1.6 TSSA. Maybe the stiff surrounds enjoy some Zo in their small box. Probably.
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Old 11th September 2012, 11:27 PM   #1074
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Originally Posted by sonnya View Post
I really dont think the SSA are completly stable... Go for Megahertz they all say.
Of course, such an open loop bandwidth needs each node of the amp to all have very close roll off frequencies , So the phase will turn very quickly at the high end, because the high Q low pass filter it represent..
Because it happens at such high frequencies, the slightest track is a coil and, all along with parasitic capacitances, has a great influence. So are each component's influence.
But, once it is stable, it stays stable ;-) So is mine.
I tried mine with 10µF, it can be stabilized, increasing the feedback compensation cap to flatten the hf response under such a charge and reduce the input filter frequency to flatten the square waves. The amp see all its wonder reduced: less bandwidth and less slewrate, of course.
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Old 12th September 2012, 01:20 AM   #1075
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Oh I misunderstood, apologize Sonny

BTW did you have opportunity yet to listen to NC400 module? I only see praises all around the net.
Hm...interesting question
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Old 12th September 2012, 02:56 AM   #1076
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Originally Posted by Lazy Cat View Post
BTW did you have opportunity yet to listen to NC400 module? I only see praises all around the net.
Good morning, Mister Lazy Cat,
Once SSA+PSU+Protection of the CSSA finished, your mission, should you choose to accept it, will be to Equal or overkill it with your own Class D amp version.
As always, should you fail in your efforts and we will deny any knowledge of your actions.
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Old 12th September 2012, 06:56 AM   #1077
dadod is offline dadod  Croatia
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Originally Posted by Esperado View Post
The amp see all its wonder reduced: less bandwidth and less slewrate, of course.
Bandwith and slewrate are not correlated, TIM is not caused by NFB. Please read some books and try not to confuse DIYers here with wrong explanations.
dado
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Old 12th September 2012, 07:11 AM   #1078
sonnya is offline sonnya  Denmark
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For VFB amps it is the case, that slewrate is not defined by bandwidth.

For CFB in simple:

Bandwidth is defined by time constant Cdom*RF.

Slewrate is defined by Cdom*RF and applied voltage on the summing point. (Diamond buffer)
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Old 12th September 2012, 10:03 AM   #1079
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Bandwith and slewrate are not correlated, TIM is not caused by NFB. Please read some books and try not to confuse DIYers here with wrong explanations.
dado
OPEN LOOP Bandwith and Slewrate are correlated, that's what i wrote. Please, read correctly and/or learn.
Open loop bandwidth is an envelop curve, witch shows the max gain an amp is able to provide for each frequency.
To understand how bandwidth depend both of the open loop bandwitch and gain factor of an amp, please, read:
Gain?bandwidth product - Wikipedia, the free encyclopedia
To understand what is slewrate, please read: http://en.wikipedia.org/wiki/Slew_rate
TIM, (also called slewrate distortion :-) is produced when the amp is not fast enough to follow the correction signal, please, learn or try to understand.
Please read some books and try not to confuse DIYers here with YOUR wrong assertions.
And, by the way, please, learn in the same time how to post in a non aggressive and disagreeable way, and not be ridiculous.
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Last edited by Esperado; 12th September 2012 at 10:23 AM.
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Old 12th September 2012, 10:24 AM   #1080
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I think we professionals and many amateurs know what Gain-Bandwidth, Slew Rate, Frequency Response, Closed Loop Bandwidth, Open Loop Bandwidth, Rise Time and such is. Still i am surprised that the discussion about the definitions comes up all the time. Usually the terms are mixed up and misinterpreted badly. Many think for example that Rise Time and Slew Rate are the same although it is quite easy to look it up on the net or in books from Self, JLH, Cordell etc.
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