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PostPosted: Mon Mar 05, 2018 11:41 am 
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Ultimately, isn't it current delivery? We bandy these specs out, as if the amplifier has infinity capacity to produce the current required to meet the spec. Who says that amount of current happens?


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PostPosted: Mon Mar 05, 2018 12:07 pm 
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Quite frankly, I don't fully understand damping factor myself.
To rephase the comments made my Pneumonic.
An amp has an output impedance and the speaker load has an impedance.
These 2 impedances create an equation called a transfer function.
If a step function or square wave is applied, the damping factor
influences the amount of time it takes for a driver to reach the location
of where it should be.
An over damped system occurs when the driver takes too much time
to reach the location where it should be.
An under damped system occurs when the driver arrives quickly, but there is ringing
and finally settles in the location where it should be.

It seems that when amp manufacturers express damping factor
its into a real impedance of 8 ohms.
Well not too many speakers have only a real impedance.
Not only that, but an amp can have a high damping factor
by increasing the amount of feedback.
It says nothing about the amount of current the amp and its power supply can deliver.
Its current that creates the magnetic field in a voice coil.

In the end, its not really a spec I look at.
Rather a much more accurate spec, that determines how much control
an amp has over a driver, is looking at the power rating from 8 to 4 ohms.
If an amp nearly doubles its power from 8 to 4 ohms,
that's an indicator it can drive difficult loads.

Now can someone here help me understand why Canadians
don't hold politicians and the media more accountable ?


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PostPosted: Mon Mar 05, 2018 12:46 pm 
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I'm not sold on damping factor... By which I mean, I'm not certain it makes a difference. But, I'm also not sure it doesn't make a difference.

I tried an Arcam Alpha... It sounded okay. But a little dull. I used my Cambridge 640A for a number of years and it always sounded a little bright. I tried a few NAD 316 and 352 or something integrateds... They were an in between. I tried my Rotel, and it had a great sound. Detailed, but not too bright. It was a good sound. I checked, and it had the higher of the damping factors of all the amps I listened to...

Is it damping factor? Or amplifier design? All were modestly priced integrateds. I've wanted to try some other amps lately... Creek Evo 50, Naim 5 and possibly something from Simaudio...

I'm not sure how their house sound would affect their respective ratings in damping.

Speakers would mostly be stand mount speakers from Focal, Tannoy, Monitor Audio. Not huge drivers. But 6.5" - 8" mid/bass drivers.

Arguably it would have the greatest impact on the 8" driver in my Monitor Silver 2...

At the end of the day, I would hope when I invest in another amplifier, I'd get something that would be a marked improvement over what I already own. I don't care if its 40w or 100w and I don't care if it has a df of 200 or 400 or 10.... Long as it sounds better than what I'm currently listening to..


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PostPosted: Mon Mar 05, 2018 12:51 pm 
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A better indicator of whether an amp has good control over a woofer is to look at the number of output devices it has. Higher is better, IMO.

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PostPosted: Mon Mar 05, 2018 1:04 pm 
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ripblade wrote:
A better indicator of whether an amp has good control over a woofer is to look at the number of output devices it has. Higher is better, IMO.

Exactly - although a certain group of DIY audiophiles will fight tooth and nail
against this, but the change from the F5 to the F5 Turbo is not about more power.
Its about lowering Zout by paralleling up more output MOSFET's.

.


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PostPosted: Mon Mar 05, 2018 1:07 pm 
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Then...there is Feed Forward.

Most amp designers, who are in the extreme audio end of their careers, go to low global/loop feedback and employ mid to low levels of feedback in critical sections of the amplifier.

This tends to sound the best, overall.

Feed back levels (higher) are tied to 'damping' number increases. Loop feedback on a whole amp circuit is plagued with temporal displacement issues, like trying to close the barn door after the horse gets out. Which is why well applied feed-forward can sound quite interesting. Variables in the real world make Feedback and Feed forward both problematic.

I believe one of Nelson Pass's latest amplifiers allows for feedback control adjustments. Scratch that, it allows for bias changes. (60.8 )

Some tube amplifiers allow for adjustability of both parameters. Sort of. Long story.

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Last edited by Teo Audio on Mon Mar 05, 2018 1:17 pm, edited 3 times in total.

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PostPosted: Mon Mar 05, 2018 1:10 pm 
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Sasklite wrote:
Glad you asked, and its been a good response. Thanks to the posters, I have learned something new today.

Was just going to post the same thing myself! Thanks to all for the knowledge.


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PostPosted: Mon Mar 05, 2018 1:24 pm 
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ripblade wrote:
A better indicator of whether an amp has good control over a woofer is to look at the number of output devices it has. Higher is better, IMO.



Except for the dirty sound brought about by too many output transistors....this might have been a good idea.

The best sounding amplifies with the cleanest clearest sound quality, with no additions and no subtractions and no obscuration of the fine detail we are actually listening for..have one to two output devices per channel. That--and no more.

I mean, this is going to be one confused sounding grungy mess:

Image

Whether it is $1000 from china or $50,000 from some western country makes no difference.

That many transistors per rail is a problem. A serious problem that is never spoken of but everyone in the business --who actually listens to the amplifiers-...... knows it is there.

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PostPosted: Mon Mar 05, 2018 1:33 pm 
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Teo Audio wrote:
ripblade wrote:
A better indicator of whether an amp has good control over a woofer is to look at the number of output devices it has. Higher is better, IMO.



Except for the dirty sound brought about by too many output transistors....this might have been a good idea.

The best sounding amplifies with the cleanest clearest sound quality, with no additions and no subtractions and no obscuration of the fine detail we are actually listening for..have one to two output devices per channel. That--and no more.

Whether it is $1000 from china or $50,000 from some western country makes no difference.

That many transistors per rail is a problem. A serious problem that is never spoken of but everyone in the business --who actually listens to the amplifiers-...... knows it is there.


Disagree totally.

All more devices does is provides lower output impedance, enabling higher current delivery.

Audible smearing of the audio signal is impossible given that electric signals propagate at near the speed of light.


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PostPosted: Mon Mar 05, 2018 1:54 pm 
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It's a nice idea, but you are wrong as can be. People hear it and remark on it all the time. :) People who build amplifiers and have built many amplifiers of each and every type, they have first hand experience in these matters. This subject has been beaten to death over at DIY audio.

Most companies won't admit it directly as it affects their bottom line. After all, nothing can be wrong with the bigger amplifiers, right? It's all supposed to be golden..spend more money and get better in every way, right?

Wrong.

Look at that thing, impressive! Like a gun with 40 barrels! My inner monkey is impressed!

If a person can't hear it or won't hear it due to other conflicting room and equipment choices combined with how their hearing is enabled and trained, then so be it.

The more discerning customers DO hear it and won't take or touch those mega-transistor amplifiers if you paid them to.

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Last edited by Teo Audio on Mon Mar 05, 2018 2:00 pm, edited 1 time in total.

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PostPosted: Mon Mar 05, 2018 2:00 pm 
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Teo Audio wrote:
ripblade wrote:
A better indicator of whether an amp has good control over a woofer is to look at the number of output devices it has. Higher is better, IMO.



Except for the dirty sound brought about by too many output transistors....this might have been a good idea.

The best sounding amplifies with the cleanest clearest sound quality, with no additions and no subtractions and no obscuration of the fine detail we are actually listening for..have one to two output devices per channel. That--and no more.
Sure, but then you need a speaker with no inductors in the signal path. Amps with lower Zout tend to have better control over the woofer and tend to produce better bass, which for me is an important part of the sonic presentation. My point was, that relying on numbers that could be attributed to massive amounts of NFB instead of good hardware is not the best way to gauge the quality or suitability of an amp for a particular speaker.

Teo Audio wrote:
It's a nice idea, but you are wrong as can be. People hear it and remark on it all the time. :)

Most companies won't admit it directly as it affects their bottom line. After all, nothing can be wrong with the bigger amplifiers, right? It's all supposed to be golden..spend more money and get better in every way, right?

Wrong.

Look at that thing, impressive! Like a gun with 40 barrels! My inner monkey is impressed!


You sound like a flea watt SET kinda guy. Good luck driving Apogee ribbons or any other speaker that presents a tough load with one or two output devices. Kablooey! :lol:

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PostPosted: Mon Mar 05, 2018 2:09 pm 
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I'm not a flea watt kinda guy, no, not at all. I like to pound reggae, iffin' I get the chance. my personal record of power applied to a pair of Apogee Duetta MKII's is..at 4 ohms....1400 watts per channel. They take it pretty well...

I've been trying to find a solution for this dilemma for a very long time. Decades. Like everyone else. I explained my solution to this problem to a very well known audio designer who's name would be recognized by pretty well every member of this forum. He is well aware of the problem. Like all of them. When I explained the solution in detail, the science, the physics, and reasoning behind it... and showed him the (c)(copyrighted schematic), he said quietly, "that's **** genius..."

Just have to get to the point where we can afford to publish an amplifier. And the given 24 transistor 600 watt 180A per channel 1000 damping factor 60 lb mono amplifier will finally sound like a single transistor pair. For the first time. I'm doing a final build test on the solution for the fourth time, in this case... on a 500/Wpc 80lb power amplifier with 32 15A 250mhz transistors.

I want it all. Just like you, just like everyone else.

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PostPosted: Mon Mar 05, 2018 2:15 pm 
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When power transistors are connected in parallel, they need to be matched sets.
Otherwise, one will start conducting more current than the others.

The power resistors connected in series with each power transistor
also helps alleviate matching problems.

Feedback is highly useful if its used properly.
The problem occurs when Feedback is used to fix a poor amp design.


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PostPosted: Mon Mar 05, 2018 2:59 pm 
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Teo Audio wrote:
I'm not a flea watt kinda guy, no, not at all. I like to pound reggae, iffin' I get the chance. my personal record of power applied to a pair of Apogee Duetta MKII's is..at 4 ohms....1400 watts per channel. They take it pretty well...

I've been trying to find a solution for this dilemma for a very long time. Decades. Like everyone else. I explained my solution to this problem to a very well known audio designer who's name would be recognized by pretty well every member of this forum. He is well aware of the problem. Like all of them. When I explained the solution in detail, the science, the physics, and reasoning behind it... and showed him the (c)(copyrighted schematic), he said quietly, "that's **** genius..."

Just have to get to the point where we can afford to publish an amplifier. And the given 24 transistor 600 watt 180A per channel 1000 damping factor 60 lb mono amplifier will finally sound like a single transistor pair. For the first time. I'm doing a final build test on the solution for the fourth time, in this case... on a 500/Wpc 80lb power amplifier with 32 15A 250mhz transistors.

I want it all. Just like you, just like everyone else.


I've been down this road.
Gamat makes large power amps with a single pair of power MOSFET's
per channel.
IXYS IXTN170P10P may well be the part number for the MOSFET they use.
Problem is, it has a massive input capacitance - which needs to be effectively driven
and secondly, it still does not solve the issue of lowering Zout.

I highly suspect Gamat solves the issue of input capacitance
by driving it with a highly biased class A/B stage.

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PostPosted: Mon Mar 05, 2018 3:13 pm 
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Teo Audio wrote:
ripblade wrote:
A better indicator of whether an amp has good control over a woofer is to look at the number of output devices it has. Higher is better, IMO.



Except for the dirty sound brought about by too many output transistors....this might have been a good idea.

The best sounding amplifies with the cleanest clearest sound quality, with no additions and no subtractions and no obscuration of the fine detail we are actually listening for..have one to two output devices per channel. That--and no more.

I mean, this is going to be one confused sounding grungy mess:

Image

Whether it is $1000 from china or $50,000 from some western country makes no difference.

That many transistors per rail is a problem. A serious problem that is never spoken of but everyone in the business --who actually listens to the amplifiers-...... knows it is there.



I have to agree completely Ken, I have a Gamut amp which uses one giant output device and it is the most transparent to source amplifier I have heard in my system.... and I have had so many now I can't count....


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