Go Back   Home > Forums > >

Chip Amps Amplifiers based on integrated circuits

Modulus-86  build thread
Modulus-86  build thread
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools
Old 28th November 2020, 03:56 AM   #5301
sjh is offline sjh  Canada
diyAudio Member
 
Join Date: May 2014
Location: Ottawa, ON
About 5 years ago I purchased 4 Modulus-86, rev 2.01 boards and the parts to build them. The intention was to use them for a set of Linkwitz Pluto's or LXMini's. When I bought the boards I also ordered all the parts from Mouser, except it turns out one key part was missing. For various reasons, including finishing a sailboat project (picture attached, sorry couldn't resist) I never actually got to building them until recently. Now I have 4 completed Modulus-86 boards ready to attach to a heatsink, chassis, power supply etc. So not done yet but much closer. I'll share the details of my workaround for the missing LME49710 which is no longer available.
The heatsinks were something I salvaged from a dumpster of an electronics company next to the one I worked at many years ago. They were too good to pass up as I knew they would come in useful for some sort of project eventually. The LM3886's on my boards don't have insulated tabs so I am just waiting for the insulators before I finish mounting the boards to the heatsinks. I plan to put the Pass analog crossover for the LXMini in the same chassis as the amps. I just built the one I ordered from the DIY Audio store when it first came out and it seems to be excellent.

Steve
Attached Images
File Type: jpg boards on heatsink 1.jpg (168.7 KB, 349 views)
File Type: jpg boards on heatsink 2.jpg (219.0 KB, 346 views)
File Type: jpg 300.jpg (876.0 KB, 326 views)
  Reply With Quote
Old 28th November 2020, 04:21 AM   #5302
sjh is offline sjh  Canada
diyAudio Member
 
Join Date: May 2014
Location: Ottawa, ON
As I mentioned in my previous post, the LME49710 is no longer available and it must have been out of stock when I ordered the other parts for my Modulus-86 boards several years ago. I did have some LME49720 in the SOIC 8 package. These are dual versions of the LME49710. Tom confirmed that my best option was to use one of the 720 chips connected such that one amp is used for the 710 function and the other is just connected as a buffer with the input connected to a static signal.
I could have used a blank SOIC to DIP8 adapter, glued the LME49720 upside down to it and soldered a few tiny wires in the correct places to achieve the desired circuit. I have done this lots of times to build test circuits. But there's a better way now. It's also getting harder for me to see to do this kind of work and I didn't feel like doing it four times. A lab tech I was working with would design adapter boards for our lab using EasyEDA and JLPcb, and we would have the boards in a week. I decided to give it a try. It took one evening to figure out the schematic and layout tool. The LME49720 and 0.1in pitch pin headers were in their library. Once I had a drc clean design I clicked on the order boards link and it took me to the JLPCB page. It was $2 for 5 boards, or $5 for 10. I only needed 4 right now but at that price ordering some extra made sense, and shipping was $11.60. So for $16 or so I had something that should be more reliable than my hand wiring the adapter circuits.
One week later the boards arrived from China by FedEx. In the next post I'll explain the steps needed to use them.
Attached Images
File Type: jpg adapters arrive.jpg (145.6 KB, 333 views)
Attached Files
File Type: zip LME49710_sub_PCB_2020-11-15.zip (5.8 KB, 6 views)
  Reply With Quote
Old 28th November 2020, 08:06 AM   #5303
tomchr is online now tomchr  Canada
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Calgary
Quote:
Originally Posted by Thepinguin View Post
What about differences between smps300reh and smps240qr , both in 30v?
For a stereo amp I would go with the SMPS300REh. The added heat sink is nice.

For powering a mono amp, the SMPS240QR should be fine.

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
  Reply With Quote
Old 28th November 2020, 09:09 AM   #5304
Thepinguin is offline Thepinguin
diyAudio Member
 
Join Date: Aug 2020
Thanks tom for confirmation
I order today all needed parts from audiophonics

Since i'll have some days arround christmas, i shoumd be able to complete the amp by year end
  Reply With Quote
Old 28th November 2020, 01:46 PM   #5305
sjh is offline sjh  Canada
diyAudio Member
 
Join Date: May 2014
Location: Ottawa, ON
Here are the details of the adaptor I made with EasyEDA and JLPCB.
An old IC socket made a convenient holder to align the 0.1 in pin headers while I soldered them in place and then soldered the soic amp to the board. A 0 ohm jumper on the 0603 spaced pads converts the spare amplifier into a unity gain non-inverting buffer connected to pins 1 and 8. Those pins are no connects on the original LME49710. That first picture isn't very good and the solder isn't as messy as it looks. Now I can solder the adaptor into the Modulus-86 board in the location for U3. The final step is to connect the input of the spare amp to ground so it's not floating. I scraped a bit of solder resist off the ground plane next to pin 8, used the end of a resistor lead to make a jumper then trimmed off the excess. The adaptor boards made for a tidy installation and you wouldn't notice that it was there if you weren't looking for it.
I would definitely recommend EasyEDA and JLpcb if you want to make a simple and quick board.
Finally I had a completed Modulus-86 ready to test. I have an old analog lab power supply, and a portable CD player makes a convenient signal source. Once I checked the output voltage with no load, I connected a speaker and hit play (at low volume). It worked! After confirming that one unit worked and the adaptor boards were correct I finished the other three Modulus boards. All four amps measured less than 1mv DC offset and worked perfectly.
I only had one other glitch while building these amps. On one board I had installed one diode backwards. I found it when checking the +/-15V rails before installing the op amps so no harm was done.
My home made coil is a bit uneven looking. I didn't have any 18g magnet wire but I found a coil in an old dc-dc supply with 18g wire. I unwound that and used it to make my output coils so the wire has a few extra little ripples in it.
Overall the Modulus boards and documentation were excellent and straightforward to assemble. I would recommend them to anyone who wants to build one themselves. For me, now that the pre-assembled units are available, if I need any more Modulus-86 I am just going to buy the assembled units from Tom. His support is great too, with quick response to any questions.

Steve
Attached Images
File Type: jpg adapter assembled.jpg (234.5 KB, 302 views)
File Type: jpg adapter install 1.jpg (268.5 KB, 89 views)
File Type: jpg adapter install 3.jpg (230.0 KB, 84 views)
File Type: jpg adapter install 4.jpg (296.2 KB, 112 views)
File Type: jpg finished board test.jpg (320.3 KB, 108 views)
  Reply With Quote
Old 29th November 2020, 01:20 AM   #5306
tomchr is online now tomchr  Canada
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Calgary
That's pretty nifty. I'm glad the build came together nicely for you.

Just a note for someone just popping into this thread: This adapter is only needed on the older revisions of the Modulus-86 boards. TI discontinued the LME49710 opamp that those boards used. The newer versions of the board use the LME49720, which is still in production.

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
  Reply With Quote
Old 1st December 2020, 07:16 PM   #5307
Thepinguin is offline Thepinguin
diyAudio Member
 
Join Date: Aug 2020
Update, all nececessary parts have been orded and received .. actually not 100% .. missing the capacitors 100uf/10V that are out of stock and should be available by 18th January ...but luckily i have some 100uf/16V spares at home ..
  Reply With Quote
Old 2nd December 2020, 01:52 AM   #5308
tomchr is online now tomchr  Canada
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Calgary
100 uF, 16 V will work just fine.

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
  Reply With Quote
Old 2nd December 2020, 06:44 AM   #5309
Thepinguin is offline Thepinguin
diyAudio Member
 
Join Date: Aug 2020
I'm still in questions about about the grounding

I see the iec socket with frounding
The smps with grounding (main and Dc)
I see the In DC of mod86 with grounding and also the In where i connect the RCA with grounding

How do i connect those?
  Reply With Quote
Old 2nd December 2020, 06:17 PM   #5310
tomchr is online now tomchr  Canada
diyAudio Member
 
tomchr's Avatar
 
Join Date: Feb 2009
Location: Calgary
IEC mains ground pin connects to the chassis with a short wire and a solder lug. Preferably use a lock nut and sand off any anodizing on the chassis so you get a good connection. This is for safety.

The SMPS ground connection connects to the safety ground solder lug as well.

The output side of the SMPS connects to the power input of the Modulus-86. Do not connect any of the three output wires to the chassis.

Pin 1 of the XLR input connects to the chassis. There's usually a solder lug for this on the XLR connector. It's conveniently located right next to pin 1.

Then pins 1,2, and 3 of the XLR connector connects to pins 1,2, and 3 of the Modulus-86 input. If your signal source or preamp has only RCA outputs, I recommend using a pseudo-differential cable: Pseudo-Differential Cable: Connect unbalanced source to balanced input – Neurochrome to connect to the Modulus-86.

That's it. All ground management is handled on the Modulus-86 board.

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
  Reply With Quote

Reply


Modulus-86  build threadHide this!Advertise here!
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Modulus-86: Composite amplifier achieving <0.0004 % THD+N. tomchr Vendor's Bazaar 2475 28th November 2020 05:02 AM
Build Thread: OBEOS Tytte71 Multi-Way 15 1st October 2011 07:02 PM
Dome's Build Thread. joe58 Full Range 12 1st September 2010 05:05 PM
SE - Build Thread soundengine355 Solid State 6 27th June 2009 01:19 AM
New Project Build Thread ryoung Multi-Way 5 19th April 2008 02:15 AM


New To Site? Need Help?

All times are GMT. The time now is 02:35 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki