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Modulus-86  build thread
Modulus-86  build thread
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Old 7th August 2020, 07:55 AM   #5191
Thepinguin is offline Thepinguin
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Thanks for feed back, will have the reading of taming the lm3886, seems to be the starting point

150w into 8ohm sounds nice.. But would not work for 4ohm loads...

A speaker is '' rated '' at a certain value (average) but when I look at impedance curve of any speaker, the Ohm value always depends on frequencies.. So a speaker has some 4ohm and 8ohms value

Its perhaps preferable to stay with a single mod86 per chanel then

Mikett : thanks for the idea... I tried it

To get my reference listening level on a few tracks, my amp is at 8.30 o'clock...
To add 3db more on the phone analyzer, I need to push the amp only a little around 9.15.. To get 3db more, I only need to push a little more... And it gets loud.. I mean LOUD in my room... And the amp keeps going...
for those who know the denon pma 2500, this things is a beast and rated only at 80w on paper...

I had in past some amps rated 100, 150w and even a rotel at 200w... But denon seems to handle better... I guess it's a matter of gain..

That's why I'm not confortable with values rated in W

I had some reading last night on this thread... Returns of owners indicate that mod86 is enough for speakers at normal listening levels...

An owner mention he had a pmc24.. And he was happy with... His comment conforts me that mod86 would be enough

I keep on my readings

Thanks for sharing
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Old 7th August 2020, 12:35 PM   #5192
Mikett is offline Mikett  Canada
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"To get 3db more, I only need to push a little more... And it gets loud"

OK to clarify things here and a little off topic, it is important to understand that the volume control only controls the level of signal incoming to the amplifier stage. The same is done with the accelerator pedal in your automobile.

Now let's suppose the pedal has 3 inches of travel from start to full depression. The amount of power the automobile has remains fixed. So I can design the system so that the first 1" of travel produces 60% of power and then the next 1" will produce 30% and the final 1" will produce 10% of power. So when using the automobile the initial feel is that the automobile is powerful relative to another scheme where the first 1" produces 10% power, the next 1" produces 20% power and the final 1" produces 70% power. The same auto would feel more powerful because as soon as I tap on the pedal a lot of power is produced and the auto accelerated hard. I have to be careful. However when I floor it to the last 1" of travel, there is nothing left hardly any extra power is produced. With the second scheme, the same car will feel sluggish but not jerky and the user will think it has less power.

The same applies to an amplifier. The gain or multiplication of boosting of the incoming signal remains FIXED. What changes is the incoming signal level via the volume control. So you can make a volume control to vary the signal non linearly. The volume control can be configured by many schemes just like the automobile. ( In fact that is exactly what modern automobiles use. (a volume control connected to your foot) So realize the rotation of the volume control does not mean anything related to the power output. The reason is that the output of it, is always magnified the same amount by the amplifier. The volume control is really and is sometimes called an attenuator which is correct. It simply reduces the incoming signal to the amplifier.

It can be just like the auto where the power comes in strong after a certain point.
It gets worse in an amplifier because the incoming signal to the volume control varies depending on the recording. On some songs it may take only half the rotation of the volume control to reach the max power the amplifier can produce. On another song, that was recorded and mastered differently, it could take three quarters rotation and it will vary by each song as well.
Only by observing/measuring the actual output or listening very loud till you hear distortion will allow you to assess the real power of the amplifier. There are other reasons why more powerful amplifiers may sound better at lower volumes but do not be fooled by the rotation of the volume control. DIYing will eventually show you why as you learn.

Last edited by Mikett; 7th August 2020 at 12:37 PM.
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Old 7th August 2020, 01:03 PM   #5193
Thepinguin is offline Thepinguin
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Thanks, it's crystal clear..

So my understanding for that diy project is that it will depend on the preamplifier I will use in front

My current idea is a diy amp with mod86

And then get a dac/preamplifier from topping or smsl with stellar measurements


Additional questions please
For a double mono, shouldnt I have double smps?

Is there any audible differences with rca input or xlr inputs?
Some Chinese dacs come with rca or xlr outputs.. The mod86 can handle any?
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Old 7th August 2020, 03:37 PM   #5194
matt_garman is offline matt_garman  United States
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Modulus-86  build thread
Quote:
Originally Posted by Thepinguin View Post
Additional questions please
For a double mono, shouldnt I have double smps?
One completed Mod86 board will drive one speaker (the lm3886 is a mono chip). So for a typical stereo build, you need two completed Mod86 boards.

You can use a single power supply to power both boards, like many consumer power amplifiers. Or you can use two power supplies, one for each board; in this route, you could put both power supplies and Mod86 boards in the same case, or have two separate enclosures.

There's really no right or wrong, there are plenty of examples in this thread of both approaches. It's really more a matter of personal preference. (I recently posted pics of my build, I use one power supply for two Mod86 boards; a compact amp was a personal goal of mine.)


Quote:
Originally Posted by Thepinguin View Post
Is there any audible differences with rca input or xlr inputs?
Some Chinese dacs come with rca or xlr outputs.. The mod86 can handle any?
Yes, the Mod86 can handle differential (XLR) or single-ended (RCA) inputs. Differential is technically superior; but there is some debate as to whether it makes an audible difference in a typical home environment with short cable runs. I personally can't hear a difference, but I'm sure others have a different opinion. Single-ended/RCA DACs and preamps are generally more readily available and cheaper, so that's another consideration.
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Old 7th August 2020, 07:11 PM   #5195
Thepinguin is offline Thepinguin
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Is that right that rca input / output is standard 2v and xlr is 4v?

So then the mod86 would output 40w regardless of input sensitivity?
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Old 7th August 2020, 07:20 PM   #5196
tomchr is offline tomchr  Canada
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Modern line level is 2 V RMS for single-ended and 4 V RMS for differential.

The input sensitivity of the Modulus-86 is 1.8 V. I.e. 1.8 V RMS on the input will give you 40 W out into 8 Ω. Thus, the Modulus-86 can be driven to clipping with any modern source.

Tom
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Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 7th August 2020, 07:24 PM   #5197
tomchr is offline tomchr  Canada
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Quote:
Originally Posted by Thepinguin View Post
To get my reference listening level on a few tracks, my amp is at 8.30 o'clock...
To add 3db more on the phone analyzer, I need to push the amp only a little around 9.15.. To get 3db more, I only need to push a little more... And it gets loud.. I mean LOUD in my room... And the amp keeps going...

... I guess it's a matter of gain..
Yep. That's how a high-gain amp behaves. Unfortunately, high gain also leads to higher noise. Tradeoffs, tradeoffs...

I would much rather that "unbearably loud" happens near 3 o'clock on the volume control. That's a much better use of the available dynamic range. The drawback of an amp designed like that is that it'll will be perceived as weak simply because you have to turn the volume past 9 o'clock for normal listening levels.

Tom
__________________
Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 7th August 2020, 07:45 PM   #5198
Thepinguin is offline Thepinguin
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Thanks for returning answer..

My friend has a technics su-g700, and it's rotary volume knob works like u describe... It's linear all the way round... It starts at 7 o'clock with 0.. Ends at 4 o'clock at 100... It's a different feeling but no weakness, at 9 o'clock it's cool beans, 10 o'clock warm beans, 11 cooking, 12 is dancing loud...

my denon, I actually don't know what looks like after 12. That thing seems endless in power... It keeps going... At noon with my speakers and it my room it's clubbing level.. Windows are rattling.... At noon, you're not done yet... And distortion are barely audible, if any

I'm not looking for these kind of levels with a diy project like yours.. I want clean and precise amp to bring me to my usual listening levels.. No more.
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Old 8th August 2020, 01:13 AM   #5199
tomchr is offline tomchr  Canada
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Unless your listening space is cavernous, the Modulus-86 will get you there.

Tom
__________________
Modulus-86, 186, 286, & 686: 40-240W (8Ω), <-120dB THD. HP-2 Headphone Amp: 660mW, <-130dB THD. Taming the LM3886.
Neurochrome : : Audio - www.neurochrome.com - Engineering : : Done : : Right
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Old 8th August 2020, 07:55 AM   #5200
Thepinguin is offline Thepinguin
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Thanks
I think I found my amp chips

I'm on vacation the next two weeks, will get time to read this thread and gather all the necessary knowledge to get me started and for my personal knowledge too to understand deeper how electronic works


I started to populate cost of this project, I end up around 500e all in, the aluminum case is the pain in the butt!!

Question : i can find an old Marantz 1060 in mint condition but the amp chips are dead : is it possible to keep the casing and preamp, take out amplifier parts and build in mod86 plus smps in?
That way I would have preamp plus a very cute looking case?
It's just an idea that pop up in my head...

Since it's diy, possibilities seems end less
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