The Modulus-86 lends itself well to solder-by-numbers. Basically: Build it according to the instructions and you'll get the performance you see on my website. Building it according to the instructions also makes it much, much easier for me to help you when something goes wrong. It's pretty rare that something does go wrong, but happens maybe once every 100-150 boards or so.
I make quite a few recommendations for power supply and enclosure on my Choosing Your Amp page. If you haven't read it yet, I suggest taking a peek.
Microphone cable works well for the input. If you can't find someone who'll sell it in bulk, the cheapest and easiest is to buy an XLR microphone cable and cut the connectors off.
I generally use AWG 16 for the rest of the internal wiring. Nothing fancy. I buy it in bulk from Mouser. I do prefer stranded over solid, but I don't see any reason to go with super flexible robotics wire unless you happen to have some.
You're quite welcome.
I have a four-channel Modulus-86 (Rev. 1.10 if I recall correctly) that powers a pair of Linkwitz LXmini speakers that I have hooked to my TV. I built that amp in 2015 and it's been running without incident even since. I often just leave it on as I'm too lazy to hit the power button.
Personally I consider speaker protection to be optional in a DIY amp. The LM3886 is a rugged chip and odds of failure are very low. But the odds are obviously not zero because that's how statistics work. I suppose it boils down to how much you value your speakers. Many sleep better at night knowing that their (expensive) speakers are protected against catastrophic amplifier failure. If you do go with speaker protection, uses a circuit that does not introduce distortion to the circuit. My Guardian-86 is an example of such a circuit.
I would consider a speaker protection circuit to be mandatory in a commercially available amp.
With a ~200 VA transformer you can usually get away with oversizing the mains fuse a bit. Just make sure to use a mains switch that can handle some current as the inrush current is pretty hard on the contact points.
If that approach works for you, the main advantages of a smart soft start like the ISS is that you get to use nicer-looking switches and you get features such as ON and STANDBY indication, 12 V trigger input, etc.
The main drawback of just increasing the fuse ampacity to make it handle the inrush current is that the fuse then doesn't provide as good protection in case something does go wrong.
Using a soft start would allow you to size the fuse such that it provides better protection.
Also note that the mechanical vibration and resulting hum emitted by larger toroidal transformers at start-up can, over time, cause the insulation of the transformer to wear through. At that point the amp will blow the fuse on start-up.
With larger power transformers I'd say a soft start is mandatory.
Tom
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Thanks Tom, great info as always. With your long replies I almost feel guilty of taking a lot of your time. You should give others a chance to answer the noob questions.
For an amp I want to use for a long time the soft start seems to be kinda essential, it sounds like it's taking a lot of stress off the components and adds a layer of safety if the fuse doesn't have to be oversized. A trigger button would be nice, I had similar problems with the high current on the switch of my microcopter and ended up with a mosfet switch because the normal switches fused together or just died quickly.
Would it be possible to turn on the ISS with an Arduino signal? I've built a remote control for the volume of my NAD amp with an Arduino and a small stepper motor and perhaps I could use one of the spare signal pins for the power of the ISS?
Your argument about speaker protection makes sense to me. Since I'm using these speakers for the foreseeable future I think I'll postpone the guardian boards and use something else for testing.
SB18 loudspeaker DIY kit - Speakerbuddies
Stefan
For an amp I want to use for a long time the soft start seems to be kinda essential, it sounds like it's taking a lot of stress off the components and adds a layer of safety if the fuse doesn't have to be oversized. A trigger button would be nice, I had similar problems with the high current on the switch of my microcopter and ended up with a mosfet switch because the normal switches fused together or just died quickly.
Would it be possible to turn on the ISS with an Arduino signal? I've built a remote control for the volume of my NAD amp with an Arduino and a small stepper motor and perhaps I could use one of the spare signal pins for the power of the ISS?
Your argument about speaker protection makes sense to me. Since I'm using these speakers for the foreseeable future I think I'll postpone the guardian boards and use something else for testing.
SB18 loudspeaker DIY kit - Speakerbuddies
Stefan
Nothing useful to add to the thread other than I love your User Name.
I think it describes a bunch of us.
I can type pretty fast with ten fingers.
Besides, I catch more flies with honey than with vinegar.Yep. The input for the power switch is an active-low 3.3 V compatible logic input. You can control it with an Arduino (assuming it outputs 0-3.3 V).
Tom
thanks for help. 926-LM317LZ/LFT1 is also available - i'll order this one;
btw. post #5480is also pretty informative
thanks for pointing ... and no luck; out of stock
i'll try to look in other places
there are LM3886 still available here in Poland made by 'National Semi' and 'On Semi'/; -maybe noob question, but ... is there any difference between f.e. 'National Semi' and 'TI' ones (like quality)?
but i'll try to look some more. a week back i've found few pieces of lm3886tf in Czech Republic
Thanks!
ONsemi does not make LM3886. They are the descendant of Motorola's semiconductor operation. Anyone who claims to have an ONsemi LM3886 is suspect.
The LM3886 was designed and manufactured by National Semiconductor. Texas Instruments ('TI') bought National in 2011. TI's and National's LM3886 units will be indentical silicon though possibly a changed logo on the package (I haven't looked lately to see if it's now a TI logo or still a NS logo).
As you have seen in the news media, there is an explosion of demand world-wide for semiconductors and other electronic components. I'm sure that TI and other companies are focusing their attention on orders from their largest customers -- automotive, 'personal electronics', etc. -- which probably leaves some of the components that audio DIYers are interested in lower priority for allocation of manufacturing capacity.
Just a couple months ago I ordered some garden variety SMT resistors that I needed as I noticed that stock was low. A week later, stock at various distributors was zero and lead time was shown as >1 year. Crazy times.
The LM3886 was designed and manufactured by National Semiconductor. Texas Instruments ('TI') bought National in 2011. TI's and National's LM3886 units will be indentical silicon though possibly a changed logo on the package (I haven't looked lately to see if it's now a TI logo or still a NS logo).
As you have seen in the news media, there is an explosion of demand world-wide for semiconductors and other electronic components. I'm sure that TI and other companies are focusing their attention on orders from their largest customers -- automotive, 'personal electronics', etc. -- which probably leaves some of the components that audio DIYers are interested in lower priority for allocation of manufacturing capacity.
Just a couple months ago I ordered some garden variety SMT resistors that I needed as I noticed that stock was low. A week later, stock at various distributors was zero and lead time was shown as >1 year. Crazy times.
The ten LM3886TF (with lead) that I just took delivery of from Mouser have the National Semiconductor logo. It's the logo from 2005ish, so the stylized N as shown below.
The 250 LM3886T I bought directly from TI also have the stylized N National logo. Well... I didn't check all 250, but the one (presumably representative sample) that came from one of those tubes does have the National logo.
Tom
The 250 LM3886T I bought directly from TI also have the stylized N National logo. Well... I didn't check all 250, but the one (presumably representative sample) that came from one of those tubes does have the National logo.
Tom
Regarding parts availability:
Currently seven parts on the Mouser project for the Modulus-86 Rev. 2.4 are out of stock. Six of them are pretty easy to find substitutes for. The last one is the LM3886, which you can still find at other sources. Or order the LM3886TF from Mouser. They say they have more coming in early/mid-September.
If you're having trouble finding substitute parts, just email me and I'll help.
Tom
Currently seven parts on the Mouser project for the Modulus-86 Rev. 2.4 are out of stock. Six of them are pretty easy to find substitutes for. The last one is the LM3886, which you can still find at other sources. Or order the LM3886TF from Mouser. They say they have more coming in early/mid-September.
If you're having trouble finding substitute parts, just email me and I'll help.
Tom
No kidding! It took me almost a full workday to find substitute parts for the next batch of Intelligent Soft Start. But I now have a box of parts ready to go to the assembly house once the boards get in.
I have plenty of stock of all of my pre-assembled circuits. At least for now it looks like my current inventory is enough to carry me through a good chunk of 2022. Hopefully the world will stabilize somewhat before I run out.
Tom
Toss me an email if you get tired of waiting. If they're going into MOD686, MOD86, or LM3886DR I'm happy to help. I know I won't need all of the 250 I bought, but I'll need over 200 for sure. That should still leave enough for a pair of MOD686es.
Tom
Right, here's a noob question:
The mains input and output of softstart modules and other devices are always marked life and neutral. Here in the UK the mains plugs are designed so you can only plug it into the socket in one direction. The european plugs (Germany) have 2 earth pins and can be plugged in the other way so life and neutral are switched.
So why are life and neutral marked on the boards if they can be switched?
Growing up in Germany we sometimes had mains noises in TVs or radios so you heard a click when the fridge started or a light was turned on or off. Plugging the mains into the socket the other way sometimes fixed the problem.
I'm aware this is a really basic question so feel free to link some wiki pages, I'm happy to read if pushed into the right direction. But i think this might come in handy for the mod86 build.
Thanks
Stefan
The mains input and output of softstart modules and other devices are always marked life and neutral. Here in the UK the mains plugs are designed so you can only plug it into the socket in one direction. The european plugs (Germany) have 2 earth pins and can be plugged in the other way so life and neutral are switched.
So why are life and neutral marked on the boards if they can be switched?
Growing up in Germany we sometimes had mains noises in TVs or radios so you heard a click when the fridge started or a light was turned on or off. Plugging the mains into the socket the other way sometimes fixed the problem.
I'm aware this is a really basic question so feel free to link some wiki pages, I'm happy to read if pushed into the right direction. But i think this might come in handy for the mod86 build.
Thanks
Stefan
Correct me if I am wrong, but you do not have a 110 hot and a neutral at the wall in europe, but instead two 110 hots 180º out of phase and a ground.
Is this correct?
David.
Europe (at least Western Europe) uses 3-phase power, so each house is fed three phases and a neutral. Lighting circuits are connected between one phase and neutral and provides 230 V. Circuits for heavier loads (washers, dryers, stoves) use the three phases with 400 V between phases. There's typically a GFCI in the panel that protects the entire house.
In addition there are shaver outlets that have a small (10 VA or something) isolation transformer built-in.
Contrast with North America where each household is fed from a 240 VCT transformer, so two phases of 120 V and a neutral.
Tom
In addition there are shaver outlets that have a small (10 VA or something) isolation transformer built-in.
Contrast with North America where each household is fed from a 240 VCT transformer, so two phases of 120 V and a neutral.
Tom
I mark live and neutral on the boards because it is safer to connect the circuit that way. The ISS, for example, switches the live connection while the neutral just goes from input to output.
Some argue that a double-pole switch is required for mains switching in the EU, but that's not entirely true. You can get away with a single pole switch as long as you provide an IEC power inlet and state that the cord must be unplugged before the power is considered to be off.
Tom
I may be moving back to Germany at some point, I'm tempted to get a few UK sockets installed in my house so one can rely on life and neutral being in the same position. Or at least mark life and neutral on the existing sockets.
Oh man this AC stuff is not making much sense to me yet. I wish I my interest would have been there 20 years earlier.
Oh man this AC stuff is not making much sense to me yet. I wish I my interest would have been there 20 years earlier.
Live and neutral should still be in the same spots on the German outlets. At least the outlets I grew up with in Denmark were clearly marked on the back with P (phase) and N (neutral).
More current installations use a 3-prong outlet. The Danish one has three prongs on the plug. Some EU countries - including Germany - use two-prong plugs with a ground connection on the outside of the plug. Other EU countries use a two-prong plug with a hole for a ground prong that sticks out of the socket.
At least now that the UK is out of the EU, all of EU is now 230 V mains voltage. The UK maintained their 240 V even though everybody else harmonized to 230 V. Most of Europe used to be 220 V.
Note that the electronics (usually) don't care about live and neutral. Getting live and neutral connected correctly is mainly a safety thing. There are some cases where the neutral is connected to the secondary of an SMPS with a capacitor to reduce noise. I would think that for those cases, you do need to get the live and neutral connected correctly for the equipment to pass the EMC requirements.
Tom
More current installations use a 3-prong outlet. The Danish one has three prongs on the plug. Some EU countries - including Germany - use two-prong plugs with a ground connection on the outside of the plug. Other EU countries use a two-prong plug with a hole for a ground prong that sticks out of the socket.
At least now that the UK is out of the EU, all of EU is now 230 V mains voltage. The UK maintained their 240 V even though everybody else harmonized to 230 V. Most of Europe used to be 220 V.
Note that the electronics (usually) don't care about live and neutral. Getting live and neutral connected correctly is mainly a safety thing. There are some cases where the neutral is connected to the secondary of an SMPS with a capacitor to reduce noise. I would think that for those cases, you do need to get the live and neutral connected correctly for the equipment to pass the EMC requirements.
Tom
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The German plugs look like the one in the top left corner of your 2nd picture and they can be plugged in both ways 180° turned. Like the UK shaver outlets with only 2 pins. The earth pin is on both sides of the plug.
No worries, my brother in law is a physics teacher. I'll have to get him to put me through year 10 again.
No worries, my brother in law is a physics teacher. I'll have to get him to put me through year 10 again.