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Chip Amps Amplifiers based on integrated circuits

Modulus-86  build thread
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Old 19th March 2015, 05:39 PM   #441
danielwritesbac is offline danielwritesbac  United States
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Originally Posted by Domi_78 View Post
Hi, How does this amp sounds? - First of all, very clean ! But, the bass are somewhat light and treble are a little sibilant. So, voices seem to be acetic and doublebass is skinny.
I use to listen an Audio Note SE 300B Quest. As we say in french, to compare tube amps and solid state amps is like to compare towels and dishcloths.
Amplified music : Solid-state valve amp <--link for "Dial-A-Tube" circuit
That's a good read but there's actually no need to modify the amp design.
A current drive effect can be easily replicated by a huge BSC with a giant size inductor, a 4 ohm or 8 ohm resistor and a cap too small for treble (these materials all go parallel to each other to create the bsc. Then the BSC unit goes series to the speaker). Nothing like a huge bit of copper to replicate the sound of an output transformer. This is a simple resistor padding approach, except that an inductor is added parallel to the resistor so that most of the amplifier's power isn't wasted into the resistor.
Lack, presence, and/or amount of current drive is applicable at any size amplifier, buffer, or preamplifier.
The point?
It is likely that made-for-tube-amp speakers don't have the proper crossover elements to support a voltage drive amplifier; however, The missing parts can be added externally.

As a bonus, any "sounds like a chip" midrange audio harmonic distortion will vanish into that resistor, never to be heard.


other notes. . .

That1200 is a pretty thing but can be a little sibilant in some (not all) conditions, depending on what drives it. It may need to be either driven appropriately or bypassed.

Modulous86 is neither an integrated amp nor voiced. You'll probably be wanting a preamp for more convenience And to better suit personal tastes.
Actually, the Modulous86 product is a nice little power amp, so we need to confine our expectations to match its actual job description. There's no tone controls, it won't flip your LP for you and you'll need to add your own preamp.
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Last edited by danielwritesbac; 19th March 2015 at 05:43 PM.
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Old 19th March 2015, 11:22 PM   #442
tomchr is offline tomchr  Canada
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Originally Posted by Domi_78 View Post
Leads coming from this transformer are insulated with a length of PTFE (ie Teflon or polytétrafluoroéthylène). This material is quite resistant.
Ah. That makes me sleep a little better at night...

Quote:
Originally Posted by Domi_78 View Post
How does this amp sounds ?
- First of all, very clean ! But, the bass are somewhat light and treble are a little sibilant. So, voices seem to be acetic and doublebass is skinny.

I use to listen an Audio Note SE 300B Quest. As we say in french, to compare tube amps and solid state amps is like to compare towels and dishcloths.
- So which one is a towel and which one is a dishcloth ? It is obvious that this is not the way to compare. I am a little bit disappointed.

Tom,
You are aficionado with 300B. So I am sure that you made some comparisons between this two amps. How do you experiment their differences ?
I actually like both. When I went from a generic but pretty darn decent solid state amp to my 300B, I found the sound of the 300B to be much more open and natural. I am guessing this is because the 300B has a relatively flat THD profile (i.e. THD vs Frequency is flat). It could also be because the 300B has mostly 2nd ard 3rd order harmonic distortion, which many report as being more pleasing to the ear. While I enjoy the 300B sound and presentation, in particular in my DG300B, I would not consider it to be precise. Especially the bass tends to be on the warm and fuzzy side. Nothing wrong with that. In fact that's why many people like tube amps...
The MOD86 is a precise amp. It's a wire with gain and that's about it... There's no coloration of the sound and its low output impedance (about 150 mOhm for R1.0 and 50 mOhm for R2.0) will control any speaker tightly. This is a blessing and a curse. If you like the precise sound, it's mostly a blessing. You will hear the grass grow on your recordings and incredible detail will be extracted. For example the cavity resonance of an acoustic guitar is cleanly reproduced. As is the detail in the fretting and picking of the guitar. Now if your speakers exhibit cone break-up in the 10+ kHz range, you'll probably find the sound a bit harsh (or precise if you like cone break-up). A tube amp will have less control over the speaker cone (higher output impedance), hence, won't excite the cone break-up as efficiently. Going from a warm and fuzzy tube bass to a precise bass, will seem like the bass goes away. Measure the SPL or listen for a while and you'll notice it's actually there. It's just very precise.
The MOD86 is now my daily driver. I really like the open and natural highs. They're like the highs of the 300B but more precise. I did miss the warmer bass at first, but appreciate the more precise bass of the MOD86 now. I plan to address The Bass Situation by building a speaker that can actually reproduce bass below 50 Hz, unlike the Dali 3A I'm using at the moment.

~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.
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Last edited by tomchr; 19th March 2015 at 11:27 PM.
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Old 19th March 2015, 11:32 PM   #443
tomchr is offline tomchr  Canada
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Originally Posted by Richidoo View Post
My engineer looked at the schematic and had favorable comments about Tom's feedback HF phase compensation, which agreed with his own 3886 research over the years. He said "this guy knows this chip and knows how to tame it."
Awesome. Thank you. Yeah, I'm getting to be rather intimately familiar with the LM3886.

~Tom
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Old 19th March 2015, 11:46 PM   #444
fas42 is offline fas42  Australia
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Quote:
Originally Posted by tomchr View Post
The MOD86 is now my daily driver. I really like the open and natural highs. They're like the highs of the 300B but more precise. I did miss the warmer bass at first, but appreciate the more precise bass of the MOD86 now. I plan to address The Bass Situation by building a speaker that can actually reproduce bass below 50 Hz, unlike the Dali 3A I'm using at the moment.

~Tom
The one thing I find so intriguing is the constant "obsession" - sorry!! - of audiophiles with "low bass" - in 30 years I have yet to hear this miraculous big, lower bass thing - systems with megasized drivers to me sound like only slightly more refined versions of the kid's car in the street, with the roof bulging up and down to the beat.

I have recordings with very intense, visceral bass - and this comes over extremely well with a properly working system - I never hunger for that 25" subwoofer for extra thud!!

...
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Old 19th March 2015, 11:59 PM   #445
maty tinman is offline maty tinman  Spain
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What advantages does a double mono mod86 amplifier?
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Old 20th March 2015, 02:15 AM   #446
billshurv is online now billshurv  United Kingdom
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Modulus-86  build thread
Just back from covent garden. I reckon we had the best seats for listening to the orchestra. No way I can reproduce that at home...
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Old 20th March 2015, 02:37 AM   #447
danielwritesbac is offline danielwritesbac  United States
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Originally Posted by tomchr View Post
. . . I did miss the warmer bass at first, but appreciate the more precise bass of the MOD86 now.. . .
Its pretty easy to warm the bass by shortchanging the in- coupling frequency to cause bass foldback distortion. Audibly, bass distortion cancels if you have an equal amount of thus and booms frequencies. Otherwise, monotony results.

I think that the ear must have both booms and thuds so as to compare thus perceive, but if you've got the in- coupling wide open (such as a dc tracker or a very huge cap value), monotonous thud-only bass results. That's very well meaning yet misses the mark just slightly. That's certainly a lot cleaner than the severely shortchanged in- coupling in the lm3886 datasheet that results in annoying blurry boom-only (and even higher pitches than that). Anyway, you need an attractive point in-between.
There IS an attractive point in-between that will "allow" you to hear a pleasantly vast variety of bass. That does exist.

A different idea is Dr. Cherry's group delay circuit http://www.epanorama.net/sff/Audio/C...0Amplifier.pdf
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Old 20th March 2015, 02:39 AM   #448
billshurv is online now billshurv  United Kingdom
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Modulus-86  build thread
Quote:
Originally Posted by danielwritesbac View Post
Its pretty easy to warm the bass by shortchanging the in- coupling frequency to cause bass foldback distortion. Audibly, bass distortion cancels if you have an equal amount of thus and booms frequencies. Otherwise, monotony results.
Any chance we can have that in English please?
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Old 20th March 2015, 02:42 AM   #449
soongsc is offline soongsc  Taiwan
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Quote:
Originally Posted by Domi_78 View Post
Hi,
How does this amp sounds ?
- First of all, very clean ! But, the bass are somewhat light and treble are a little sibilant. So, voices seem to be acetic and doublebass is skinny.

I use to listen an Audio Note SE 300B Quest. As we say in french, to compare tube amps and solid state amps is like to compare towels and dishcloths.
- So which one is a towel and which one is a dishcloth ? It is obvious that this is not the way to compare. I am a little bit disappointed.

Tom,
You are aficionado with 300B. So I am sure that you made some comparisons between this two amps. How do you experiment their differences ?
It seems similar to what I would expect since tube amplifiers have output transformers that are basically delivering current. This is an advantage when driving through Fs type impedance peaks due to system resonance. I would love to hear Tom's impression as well. (Just read it)
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Last edited by soongsc; 20th March 2015 at 02:46 AM.
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Old 20th March 2015, 02:47 AM   #450
fas42 is offline fas42  Australia
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Originally Posted by billshurv View Post
No way I can reproduce that at home...
What do you feel would be lacking - why would it fail to "convince" you?
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