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What causes grainy sound
What causes grainy sound
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Old 19th September 2019, 06:14 PM   #21
Ken Newton is offline Ken Newton  United States
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Except, that your question inherently solidly touches the subjective/objective debate. As I read your original question, you're looking for objective explanation for your subjective observation that some amps sound 'grainy' while others don't. Generally speaking, the answer is sort of a holy grail of amplifier design. What objectively is it, exactly, that produces certain subjective perceptions of the sound character of a component.
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Old 19th September 2019, 06:16 PM   #22
cumbb is offline cumbb
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Quote:
Originally Posted by skem View Post
I’m simply looking for tips on what to experiment with in my amps. :-)
What are your speakers?
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Old 19th September 2019, 06:53 PM   #23
Ramcres is offline Ramcres
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Originally Posted by analog_sa View Post
Don't get it. A small current range is what class A is about. Or even zero current range. You see a problem with class A operation?

I mean the current difference between the minimum and maximum signal.

there are amplifiers speciallly with high open loop gain that some of its stages work
with a very small range of current ,
and is independent of the bias current .

Obviously could be anothers things that causes grain , but for my experience
this can be one .

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Old 19th September 2019, 07:14 PM   #24
cumbb is offline cumbb
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My experience:

Many parts, many stages, complementary-transistors-pp-stages and many psus (double-mono as ex.) do grain. And ambiguous circuits too.

A lot of parts sound very "grainy": the most condensers, wirewound resistors, solder joints often, MosFets (compared with BjTs)...

Speakers: by many others complex crossovers too. The most multiway-speakers do graín very well;-)-;

Have you built the F5?
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Old 19th September 2019, 08:37 PM   #25
Vrystaat is offline Vrystaat  South Africa
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cumbb, a decent build diy class AB Slewmaster amp has none of those bad sounding things you are talking about !
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Old 19th September 2019, 08:45 PM   #26
analog_sa is offline analog_sa  Europe
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What causes grainy sound
Quote:
Originally Posted by Ramcres View Post
I mean the current difference between the minimum and maximum signal.
I know what you mean but did you understand my response?
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Old 20th September 2019, 01:09 AM   #27
johnego is offline johnego  Indonesia
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Quote:
Originally Posted by Ramcres View Post
I have my own theory, although it has not been proven. And it is the use of transistors inside the circuit that work within
a small current range. This is normally associated with small signal transistors in early stages,

The major graininess is associated with class B operation. The more you bias the output stage (which is usually the biggest contributor of distortions), the less grainy it is. So class A amps are in general much smoother than class B amps.


And there are 'minor' graininess, that is harder to perceive by most people.


Skem was talking about the correlation with the age of the equipment. Even a new part has minor effect on graininess. Old parts are even worse, so people like to replace parts in old equipment. It is not all old parts, but you don't know which one is the broken one so usually you have to replace all. Capacitors are the major suspect, but it happened with resistors too, and even diodes.


Some people will do everything to avoid input coupling cap (using servo). If it is metalized caps, possibility for grainy sound is quite high.


People usually 'listen' to part's sound in a simple circuit because there usually the effect is more audible. In complex circuit it is not so. Some think it is because the performance of the complex amp is less determined by the quality of the parts. Or may be it is because the complex amps do not have the quality people think they have (coz quality is associated with wrong numbers). In my experience, with the complex amps, when you have done everything right in the end you will still be left with choosing the right parts.


And YES, input transistor is critical. When the amp is not optimized, it is hard to know what parameters are most needed. In my experience when the best result is the objective and the circuit is optimized, noise parameter becomes important and (surprisingly) audible. Current gain is important too (low noise parts are usually low gain device and high current gain is usually low voltage device), so I usually have to purchase more than needed to get the highest current gain.


In a complex amp, before dealing with the 'minor' graininess contributors, the amp must be first optimized. There are too many things unknown to public that many people will never understand. It doesn't matter if you have chosen the right transistors, caps, resistors, bias currents, there are still things you need to know in the amp design that will affect graininess.
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Old 20th September 2019, 09:51 AM   #28
cumbb is offline cumbb
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cumbb, a decent build diy class AB Slewmaster amp has none of those bad sounding things you are talking about !
None;-)
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Old 20th September 2019, 01:30 PM   #29
StewartH83 is offline StewartH83  England
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I like alot of everyone's input here

I feel on older equipment the components get noisy. Mostly caps, transistors and low wattage resistors.

I bought a old Denon PMA-250 mk 3 to play around with, it was sold with scratchy volume control and input selector, which were cleaned with Servisol Super 10 which sorted that out.

The sound was noisy, grainy, shouty, instruments were splashy and over enthusiastic.

After replacing the 3 core mains cable someone earthed to the chassis it sounded better. Recapped it and sounded well better, biggest improvement. I noticed the inputs were noisier than others so replaced the 1/4W resistors on the inputs to new mox ones and all inputs were great.

This lead me to replace all 1/4W ceramic resistors in the power supply. Absolutely great difference in noise and no fatiguing grain.

I will replace transistors as they are known to be noisey types.

Already sounds like a new amp.
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Old 20th September 2019, 01:41 PM   #30
xrk971 is offline xrk971  United States
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What causes grainy sound
Graininess can also sometimes be very low levels of higher order odd harmonic distortion components. SE Class A amps tend to have less of that too.
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