LM3886 Class AB "gainclone" chip-amps - DIY , kit and assembled since 1999...

[Xulonn]

After seeing Amir's review of the excellent $1,300 Neurochrome Modulus-286 (kit) amplifier:

and a new thread started today by the owner of an Akitika GT-102 ($314 kit, $488 assembled):

- and after considering the purchase of a $165 Chinese LM3886 amplifier with balanced XLR input:

I realized that I had not been aware of this family of Class AB chip-amps. From what I could find on the internet, the LM3886 is a low distortion, fairly high output and low distortion op-amp that required careful implementation. If not engineereed properly, LM386-based amplifiers can apparently cause problems including severe distortion, particularly at low frequencies, when driving 4Ω speakers.

Tom Christiansen, the owner of Neurochrome, is an electronics engineer who built the kit for Amir to test, and actually worked in op-amp design at Texas Instruments/National Semiconductor. He has this to say about the LM3886:

The National Semiconductor (now Texas Instruments) LM3886 chip amp is a pretty nice little chip. With headline specs touting nearly 70 W of output power at 0.03 % THD and the ability to source over 11 A, what’s not to like? Well, as with any high-performance IC, it takes some engineering to get the circuit to live up to the data sheet specs. In particular with power op-amps, such as LM3886, the PCB layout or point-to-point wiring routes make a significant difference in the circuit performance. Judging by the chatter on the DIY Audio Chip Amps Forum, the main challenges for designers appear to be stability, bypassing, grounding, layout, and thermal design. My intent with these pages is to explore some of the common pitfalls and provide a design guide to a successful LM3886 design.

Like Class-D amplifiers, a decent chip is only a start. I am aware that it takes good engineering and proper implementation to make a good audio amplifier. Look at the dizzying array of LM3886 modules at this image-based search page. I wonder how many of them are "well-engineered"? I didn't take time to dredge through posts at the various DIY audio forums, but there is a long history of DIY "gain-clone" LM3886-based amplifiers, and I can only assume that there is a wide variation in reliability, consistency and quality of the LM3886 modules.

Although I considered the above cheap Chinese LM3886 amplifier with its balanced XLR inputs as a backup to my soon-to-be-completed ICEpower 200asx/200AS Ghent audio balanced XLR amp, I decided to stick with a RCA input TDA7498E Class-D amp for backup.

I'll be interested to follow any discussion of this by ASR regulars who are familiar with this class of amplifiers.

It would be interesting if Amir could test the Chinese balanced XLR version, because if it performs decently, it would be an excellent choice for those who want a medium-power, budget Class AB amp to connect via XLR to a USB DAC.

 

[Bamboszek]

IMHO Modulus-286 doesn't really fit to simple gainclone badge. It is composite amplfier, it uses LM3886 but in much more complex topology. Basically LM3886 is placed in LME49720 feedback loop so in really simple words first chip just delivers power while second one ensures precision. This kind of operation requires lots of tinkering to get it working. "LM3886 Done Right" is much closer to traditional gainclone like other amps mentioned.

 

[amirm]

I am game picking up a module to test. There are so many choices though. Is there a more talked about one?

 

[Xulonn]

You're correct - Neurochrome lists all of its other modules/kits as "composite amplifiers," but I included the Modulus-286 as an example of a gainclone favorite chip carried to an extreme to show just how much potential some chips can have. The Neurochrome "LM3886 Done Right" gainclone board is much more expensive that the cheap Chinese versions.

Tom Christiansen said in the comments following Amir's review of the Mod-286 amp - which you paraphrased:

My Modulus-series of amplifiers uses the LM3886. That's the only thing they have in common with the Gainclone. The power output comes from the LM3886, but the precision from an LME49720. It's a completely different architecture than a Gainclone.

 

[ay7ru]

This site is very intersting. Mesuarment from Amirm is really great.
I have a question espessially about this LM3886.
LM3886 sounds good, and Jeff Rowland like produce ampfillers built on this LM.
And Arcam FMJ-19 built on LM3886 too. - Much reviews in different audio magazines.
So - LM3886 has an output current - 11.5 A
And Jeff Rowland put 6 x LM3886 in one channel (Model 10).
If Ohm's law works for 35V (power supply voltage) and 2 Ohm load = 17A current (2xLM3886 needed)?
My speakers 4 Ohm by datasheet may have real impedance about 2 Ohms in some freq.
Is it possible to include in test 2 Ohms load?
Supply voltage and max current for this load?
And for D-class ampfillers mark of chip and power supply voltage? - really intersting output nominal current.

 

[Laurent]

After seeing Amir's review of the excellent $1,300 Neurochrome Modulus-286 (kit) amplifier:
View attachment 27355

and a new thread started today by the owner of an Akitika GT-102 ($314 kit, $488 assembled):
View attachment 27356

- and after considering the purchase of a $165 Chinese LM3886 amplifier with balanced XLR input:
View attachment 27357

I realized that I had not been aware of this family of Class AB chip-amps. From what I could find on the internet, the LM3886 is a low distortion, fairly high output and low distortion op-amp that required careful implementation. If not engineereed properly, LM386-based amplifiers can apparently cause problems including severe distortion, particularly at low frequencies, when driving 4Ω speakers.

Tom Christiansen, the owner of Neurochrome, is an electronics engineer who built the kit for Amir to test, and actually worked in op-amp design at Texas Instruments/National Semiconductor. He has this to say about the LM3886:



Like Class-D amplifiers, a decent chip is only a start. I am aware that it takes good engineering and proper implementation to make a good audio amplifier. Look at the dizzying array of LM3886 modules at this image-based search page. I wonder how many of them are "well-engineered"? I didn't take time to dredge through posts at the various DIY audio forums, but there is a long history of DIY "gain-clone" LM3886-based amplifiers, and I can only assume that there is a wide variation in reliability, consistency and quality of the LM3886 modules.

Although I considered the above cheap Chinese LM3886 amplifier with its balanced XLR inputs as a backup to my soon-to-be-completed ICEpower 200asx/200AS Ghent audio balanced XLR amp, I decided to stick with a RCA input TDA7498E Class-D amp for backup.

I'll be interested to follow any discussion of this by ASR regulars who are familiar with this class of amplifiers.

It would be interesting if Amir could test the Chinese balanced XLR version, because if it performs decently, it would be an excellent choice for those who want a medium-power, budget Class AB amp to connect via XLR to a USB DAC.

That amp would be perfect as a base for a modulus-86, either as mono bloc or even stereo amp for not too power hungry applications.

 

[gene_stl]

Is anyone aware of commercial products utilizing the LM3886 chip?
I am unwilling to risk my unobtanium drivers on Chinese boards which are said to have counterfeit chips.

 

[bunkbail]

Is anyone aware of commercial products utilizing the LM3886 chip?
I am unwilling to risk my unobtanium drivers on Chinese boards which are said to have counterfeit chips.

Akitika GT-102 is a popular suggestion and reviewed quite favorably by Stereophile.

Edit: Didn't realize it was mentioned in the original post as well. It is available as a kit as well as a finished, assembled unit.

 

[gene_stl]

It has a single ended power supply and an output coupling capacitor. It was originally designed as a replacement for the amplifier boards in the single ended Dyna Stereo 120. The maker then started selling complete amps with case and transformer so you didn't have to come up with a Dyna and also made it available fully assembled.

The only thing I have seen so far is the Burson Bang.

I hope to find something like a multi channel Emotiva or Outlaw. Maybe I shouldn't worry about what's inside it.

 

[Panelhead]

The French company Micromega has one current amplifier using LM3886. MyAmp. Available from Accessories for Less for 279.00.
The previous version of big boy Micromega amps had two models with LM3886. The IA-60 had a single LM3886 per channel. The IA-100 has two in parallel.
Not sure what powers the latest M-One Series. The 4500.00 M-100 may have the same topology as the IA-100.
A version like the the Jeff Rowland M-10, bridged with three sections in parallel will drive most any speaker.
I have a 15 year old diy, composite amp with the paralleled LM3886. It drove 15 ohm, 100 dB horns, Quads, and B&W 801 Matrix II equally well. The B&W are current hungry and inefficient.
No amp with a single LM3886 per channel can drive 2 ohm loads. Paralleled LM3886 can.

 

[DaveFred]

- and after considering the purchase of a $165 Chinese LM3886 amplifier with balanced XLR input:

Has anyone tried this amp?

 

[spalmgre]

Here a very interesting LM3886 amplifier board with integrated SMPS (power supply). I have asked if the 3886 circuits is original TI IC. aThis is the answer I got:
"Hi, We buy parts from reputable suppliers, and up to this date we haven't had issues with LM3886 ICs. The fact that is genuine or not has little to do with noise but a lot more with reliability. Fake chip will undeliver, and possibly blow up when reach the rated power. Probably noisy, but I haven't tried one yet. "
I think one must understand the last part of the answer as that there have not been problems YET.
https://connexelectronic.com/product/lm3886smps/

 

[DaveFred]

Here a very interesting LM3886 amplifier board with integrated SMPS (power supply). I have asked if the 3886 circuits is original TI IC. aThis is the answer I got:
"Hi, We buy parts from reputable suppliers, and up to this date we haven't had issues with LM3886 ICs. The fact that is genuine or not has little to do with noise but a lot more with reliability. Fake chip will undeliver, and possibly blow up when reach the rated power. Probably noisy, but I haven't tried one yet. "
I think one must understand the last part of the answer as that there have not been problems YET.
https://connexelectronic.com/product/lm3886smps/

That is rather cool looking, I wonder how it sounds/measures?

 

[Panelhead]

That is very nice. Have not seen many Gainclones with a switching supply. Good to see unique applications.
I use a LM3886 based amp with a resonant mode supply. Like a switcher, but not exactly the same. No spikes at multiples of the power line frequency.

 

[somebodyelse]

Here a very interesting LM3886 amplifier board with integrated SMPS (power supply). I have asked if the 3886 circuits is original TI IC. aThis is the answer I got:
"Hi, We buy parts from reputable suppliers, and up to this date we haven't had issues with LM3886 ICs. The fact that is genuine or not has little to do with noise but a lot more with reliability. Fake chip will undeliver, and possibly blow up when reach the rated power. Probably noisy, but I haven't tried one yet. "
I think one must understand the last part of the answer as that there have not been problems YET.
https://connexelectronic.com/product/lm3886smps/

I think that's the manufacturer of the SMPS Tom used in the reviewed Modulus-286 - a custom version of their SMPS300RE judging by the photos in the review.

 

[spalmgre]

Connexelectronic.com has very nice documentation on their smps. Hifimediy.com also sells their 300/500/600smps. These are Chinese webshops I have found that answer if you send them questions.
See documentation http://connexelectronic.com/wp-content/uploads/2017/09/SMPS500R.pdf

 

[pma]

I realized that I had not been aware of this family of Class AB chip-amps. From what I could find on the internet, the LM3886 is a low distortion, fairly high output and low distortion op-amp that required careful implementation. If not engineered properly, LM386-based amplifiers can apparently cause problems including severe distortion, particularly at low frequencies, when driving 4Ω speakers.

I agree with the need of "careful implementation", at least. 11 years ago I designed an amp based on LM3886 and I did not like, especially due to tricky and unpredictable behaviour into low impedance complex loads.

 

[spalmgre]

My interest in the Connexelectronic 3886 application is that it is ready to use just connect some in-, outputs, and ad a heatsink. I have too many projects going on to start fiddling with another unstable amplifier.
The LM3886 is interesting as the datasheet says that the signal-to-noise ratio is 92db and that the noise floor is 2.0uV witch sounds pretty good. I have JBL compression drivers and you can easily hear if there is any his. Even my JBL 2123 10in mid drivers does revile if there is any his.

 

[Tave5]

I have an LM3886 Amp made by a talented guy in Canada .. ( Wayne Bishop ). It floored me how good this DIY AB Chip Amp is. What do I compare it to and how good is it? Just to give you an idea comparison wise I have/ had these Amps ( Valvet E-3 - Class A Clayton S100. - Spec Corp RSA V1 - DT
Bakoon 5514 / Pioneer M22 and Pioneer TA-4650 V FET just to name a few!

 

[restorer-john]

Pioneer TA-4650 V FET just to name a few!

Sony.